Exergy for A Better Environment and Improved Sustainability 1

Metal hydride pump (MHP) is one of the unconventional pumping systems which converts thermal energy into mechanical energy. This pump operates in an autonomous mode without the consumption of electric power. So, it is used to solve problems of availability of electricity or fossil energies in certain freestanding regions.In this paper, a mathematical model that describes a dynamic behavior of a MHP is carried out with Mg₂Ni alloy using an unsteady model (the time-space evolution of temperature and hydrogen concentration within the reactor is taken into account). Using this model, a computer code has been developed and used to predict the time evolution of the specific water discharge and the effect of different operating parameters (heating temperature, desorption gear ratio, surfaces of hydrogen, and pumping pistons) on the performance of the MHP. Simulation results show that depending on operating conditions, it is possible to pump as much as 890 L of water at a desorption temperature of 673 K using 1 kg of Mg₂Ni.

In this study, in order to indicate the best airfoil profile for the different sections of a blade, five airfoils including S8xx, FFA, and AH series were studied. Among the most popular wind power blades for this application were selected, in order to find the optimum performance. Nowadays, modern wind turbines are using blades with multi-airfoils at different sections. On the large scale profile, SST K-ω model with different wind speed at large-scale profile was applied to the simulation of horizontal axis wind turbines (HAWT). The aerodynamic simulation was accomplished using the computational fluid dynamic (CFD) method based on the finite volume method. The governing equations applied in this simulation are the unsteady Reynolds-averaged Navier-Stokes (URANS) equations. The aerodynamic coefficients of lift and drag were calculated at different angles of attack and different wind speeds. The results were validated by the Eppler code, Xfoil, and experimental data of the US National Renewable Energy Laboratory (NREL). The results showed that S818 profile is the best profile in terms of gaining the highest lift coefficient with the lowest angle of attack at the root of the blades. The results also indicated that the selected model can predict the exact geometry with a high precision.

Low-permeability gas reservoirs, which are widely distributed in China Offshore, could hardly be developed, due to the restrictions of the platform. LS gas field has the characteristic: prematurely senile appearance. That means it is currently in the middle period of development but has many features of the later period of the gas field’s life. There are two types of reservoirs in this gas field: conventional reservoirs distributed in the upper stratum and unconventional reservoirs with low porosity and low permeability distributed in the lower stratum. In order to compensate the decline of conventional gas production, the development of unconventional reservoirs has taken place during the past years.In LS gas field, the permeability of unconventional gas reservoirs ranges between 0.3 and 1 mD. The developing practice shows that the reservoirs with permeability lower than 1 mD don’t have natural productivity to maintain production. Hence, practices have been implemented gradually: acid fracturing, sand fracturing, low-cost fracturing based on platform, integration of completion fracturing, etc. After several years of practice, the sand fracturing technology was developed to be a proven technology and was selected preferentially.This paper presented: Design of sand fracturing, including the parameters such as sand amount, fracture size, etc. Equations (some are based on theories and some are based on experience) have been deduced to calculate productivity for production wells after sand fractured. Numerical simulation in accordance with the equations was applied in low-permeability gas reservoirs. Analyzing and evaluating the sand fracturing in different types of reservoirs. Calculation and prediction of the gradient stress could provide guidance for sand fracturing. Sensitivity and uncertainty analysis of the parameters in simulation. Furthermore, the future trend of unconventional reservoirs’ development was also discussed in this paper.

Low-permeability gas reservoirs, which are widely distributed in China offshore, have maintained a rapid increase on exploration reserve during the past years. The low-permeability gas reservoirs in China offshore gas field have low porosity and low permeability which range between 0.3 and 1 mD. Developing practice shows that these reservoirs could hardly be developed. Due to the characteristics: poor physical property, low reserves abundance, low recovery, etc., the research of porous flow mechanism is important to the gas field’s development.This study researched the following: microscopic mechanism of the water-gas flow in low-permeability sandstone through the core experiment, measurement method for water saturation with nuclear magnetic resonance (NMR) technology, calculation method for mobile water saturation measurement, effect of the crustal stress on permeability of the core in accordance with the reservoir under high pressure, etc.This paper presented several methods and viewpoints: the mobile water saturation is around a fixed high value in the research area; due to the high value, most of the gas production wells would produce water with gas in the early time; the crustal stress has a low sensitivity in the research area; the gas permeability and water permeability under the high-pressure environment are lower than in the traditional condition.By summarizing the viewpoints, the overall analysis method based on permeability, porosity, gas saturation, mobile water saturation, etc. could be proposed. It could provide quantitative basis for productivity calculation and guidance for the gas field’s development.

In this study, we present a numerical analysis of dynamic and thermal behavior of a laminar flow (Re = 100 – 2000) in a horizontal channel fitted with circular and triangular cavities on the top and bottom walls. According to the number of cavities (N = 3, 6, and 12) on each wall of the channel, six configurations are analyzed. The governing equations of the problem are solved by the finite volume method using the commercial code Fluent. The results obtained are shown in terms of pressure loss and Nusselt number.

In this work, a steady three-dimensional RANS numerical simulation has been carried out to investigate the air flow field of a centrifugal compressor used for the turbocharger applications; such a compressor consists of a simple-splitter impeller followed by a vaned diffuser. Particular attention is focused on the diffuser solidity effect on the performance of the turbocharger centrifugal compressor by varying the number of diffuser vanes without changing the number of impeller blades. It is found from the computational fluid dynamics analysis that the diffuser solidity presents a considerable effect on the fluid flow field and turbulence characteristics and then on the performances and operating range of the turbocharger compressor.

The present work reports the evolution of multiple turbulent jets that emanate from axisymmetric nozzles arranged in a particular configuration. Five cases are considered for this present work. A Reynolds number of 25,000 based on the equivalent diameter is kept constant for all the cases. The measurements along the geometric centreline provide axial evolution. Profiles of measured mean axial velocity show the merger and growth of multiple jets at various axial downstream locations. Non-linear behaviour of multiple jets is found in the near-field region. The evolutions of flow from nozzle configurations with and without central jets are found to be different.

Mixing layer growth rate is studied. Experiments are carried out in a low speed shear layer tunnel, where two flows originating from different blowers with different velocity and different turbulence characteristics coalesce at the sharp splitter plate edge forming the sheared mixing layer. Using different grids, two energy containing flows are produced and their thickness growth is studied with and without shear. Simulations are done in k-ε model to validate these flow configurations.

In this study, natural convection heat transfer of water-based CuO and water-based Al₂O₃ nanofluids through a horizontal plate at steady-state temperature has been investigated. Fluid was assumed Newtonian and incompressible and flow two dimensional and laminar. It is assumed that the only force acting on the fluid is the force of gravity. Governing equations of flow and heat transfer have been solved by COMSOL Multiphysics 4.3 Simulation Program. In the literature, various models have been proposed to determine the thermal conductivity coefficient of the nanofluids. Yu and Choi model (2013)l, for nanofluid thermal conductivity, and Brinkman’s (1952) model, for viscosity of nanofluid, are used in this study. Computational results are obtained for nanoparticle volume fractions of 0, 0.5%, and 10% and for Rayleigh numbers ranging from 104, 105, and 106. Results show that usage of nanoparticle causes a significant increase at heat transfer rate from horizontal plate.

Coriolis flow meters are widely used in hydrogen flow measurements. The low molecular weight and low density makes it difficult for conventional techniques to measure hydrogen flow. Many researchers have worked on the FE analysis of Coriolis mass flow meter. Here, a three-node Timoshenko beam element is formulated to model the curved pipe conveying hydrogen in three-dimensional configuration. Paidoussis and Issid (J Sound Vibr 29(3):267–294, 1974) derived the equations of motion for the combined structure and fluid domain including added mass effect, Coriolis effect, centrifugal effect, and the effect of pressure on the walls of the pipe. These equations are converted to the FE formulation using Galerkin technique and are validated.

A solar chimney power plant has been analysed in this paper by two numerical studies. Firstly we are interested on the wind turbine blades by proposing an approach in perfect fluid model for design. In the case of wind turbine, the tridimensional design is performed by either of the two steps S2 (meridional flow) or S1 (blade-to-blade flow) approach. In this model, a set of governing equations is derived from continuity and momentum equations for the three-dimensional rotational steady flow relative to the wind turbine. The blade geometry is determined according to a specified blade bound circulation distribution by iterative computation. S2 step leads to the determination of axisymmetrical stream sheets as well as the approximate camber surface of the blades. In the S1 step, the inverse problem concerning blade-to-blade flow for wind turbine is carried out. Secondly a numerical simulation has been performed to analyse the characteristics of heat transfer and air flow in the solar chimney power plant system at night (absence of solar radiations). So the production of solar chimney power plant on a continuous, 24 h basis is possible by applying geothermal energy.

The theoretical models that have been developed to predict forces acting on lift-type vertical wind turbine blades have been reviewed. These models were categorized into two groups: conservation of momentum-based group and vortex-based group. The comparisons of calculation with experiment between these groups which based on results extracted from published papers have been provided. Finally recommendations have been suggested for models that should be applied for performance predication of lift-type vertical-axis wind turbines VAWTs in Libya.

The present work concerns the modeling and numerical simulation of the melting of a phase change material (PCM) in a latent heat storage unit. A mathematical model based on the conservation equations of mass, momentum, and energy has been developed. These equations are then discretized using the finite volume approach and the pressure correction method for the treatment of velocity-pressure coupling. The energy conservation equation of PCM was formulated using the enthalpy method. A series of simulations were carried out on a type of phase change material (Paraffin Wax P116) to study the impact of the mass flow rate and heat transfer fluid (HTF) inlet temperature on the performance of the storage unit. The flow structure and the temperature field are also investigated.

Human body acts as a heat engine and thermodynamically could be considered as an open system. The energy conversion and exergy analysis is obtained by applying the first and second laws of thermodynamic for this open system. The second law of thermodynamics introduces the useful concept of exergy. It enables the determination of the exergy consumption within the human body dependent on the human body parameters and environmental factors.Energy generated by metabolism is an important factor on exergy efficiency and entropy generation of the body. Age is one of the parameters which has an effect on metabolism. In this paper, the thermal behavior of the human body is stimulated with two node models, and the human body parameters like age, mass, length, and weight are considered. The results indicate that the exergy efficiency increases until youth stage and after that it decreases during life span.

This paper deals with modeling, simulation, and experimental solid/fluid flow in a pipe. Our approach focuses on particle interaction and motion behavior along the experimental section of a pipe. The motion of large calibrated beads of alumina in a turbulent water flow in a horizontal pipe is experimentally investigated. We also present an experimental study of the hydraulic transport of big solid particles in a horizontal pipe. Particle motion in the liquid is captured with a CCD camera. For image processing, a computing code is developed in order to visualize the particle trajectories. The modeling and simulation of the movement of a solid particle in a liquid flow are done. Modeled trajectories compared with experimental results show good agreement.

Solar power concentration is one of the most promising mean for the production of electricity by renewable energies.At the focus of a solar power concentration system, the radiation is received, and the thermal flux is maximum. Therefore, the energy conservation in this area is the mandatory requirement. The temperature increasing at maximum depends, mainly, on the characteristics of the device which intercepts the solar radiation; it is “the solar receiver.”The receiver is exposed to repeated cycles and subjected to a very high thermal stresses. It seems that it is the key element playing an important role in the solar electricity production.For that reason, it is necessary to make a receiver modeling (surface, volumetric, external, etc.) and a simulation of heat transfer at their level in order to identify the advantages and disadvantages of the considered receiver that should be the most efficient. We modeled the process to establish the properties related to heat transfer involving the volumetric receiver in the solar tower, thus using a computational code based on finite volume method (Fluent CFD).This study examines numerically the heat exchange rate through a designed receiver for a solar tower in order to evaluate its thermal characterization. Thus, using a computational code based on finite volume method (Fluent CFD) sought to extend our study by generalizing the problem to geometry, coolant fluid, and its mass flux effects when the used receiver is a surface tubular receiver.Finally, we evaluated the obtained results versus those already existing in specialized literature in order to provide optimal energy efficiency sought.

This work presents a numerical study on the thermal behavior of a PCM heat sink for the purpose of electronic cooling. Introducing copper fins inside a PCM heat sink was examined. A parametric study was performed to maximize the critical time elapsed before reaching the allowable temperature limit for different fin lengths, numbers, and thicknesses for the same copper amount. This amount was also evaluated as a perimeter envelope of the PCM. The enthalpy method was carried out. Natural convection in melted PCM was taken into account. The governing equations were solved by Comsol Multiphysics. This model was validated by comparing results with numerical data by Huang et al. (Int J Heat Mass Transf 47:2715–2733, 2004). The results indicated that the inclusion of fins can enhance the thermal performance of heat sink by increasing the exchange surface and ensuring better heat repartition inside the PCM. The fin geometry presented an important role in thermal control improvement. Although a significant difference was showed in temperature between the copper envelope and the copper fins, they present the same efficience for low heat flux.

In this chapter, aerodynamics analysis of Vestas V47 wind turbine is implemented by the use of modified blade element momentum (BEM) theory to determine aerodynamics performances such as output power, axial, and tangential forces which can be coupled with structural analysis to predict aeroelastic behavior of wind turbine blade. Unlike most BEM analysis of a wind turbine blade, in this code effect of drag coefficient is considered to have more accuracy results. Also convenient critical axial induction factor in Glauert correction is determined. Another correction which is Prandtl tip loss factor is considered and the effect of these correction factors is obtained. To validate current analysis, the only available data is real field measurement that is done by Vestas Company and power and power coefficient are compared with these data.

In this chapter, a computational fluid dynamics (CFD numerical model) of the air flow through a 300 cm3 Beta Stirling engine has been used to characterize the pressure drop and heat transfer through the regenerator. The Stirling engine had two moving parts (i.e. piston and displacer) which were at a certain phase difference but reciprocated at same frequencies. First, particular specific mesh motion strategies were developed using the software STARCCM+, to describe the motion of the power piston and the displacer. Heat-transfer models were implemented by taking into account the presence of two heat sources and the regenerator porous structure. The results are compared with experimental data. Heat transfer between the air flow and the matrix has been considered by varying the hot end temperature from 400 to 1000 K and keeping the wall temperature of the regenerator at 300 K. Regenerator properties such as matrix material and porosity are investigated.

Determining the temperature of several steel coils, heated in a furnace traversed by hydrogen, is approached by numerical modeling using differential equations governing heat transfers involved. The resolution is performed by the method of finite differences. Convergence standards of different numerical algorithms are adjusted on the basis of a compromise precision time by the method of experimental plan. Thermal coefficients used in the model are also adjusted by the simplex optimization technique. Finally, the temperature measurement is performed in a coil for annealing of geometric configurations at different temperature set points, and the error between modeled and measured temperature is less than 10 K in mean absolute deviation.

In this paper, various aspects of solar air heaters applied to drying process are investigated. This study presents a mathematical model for simulating the transient processes which occur in solar air collectors with flat plate and V-corrugated absorbers. The proposed model is time-dependent and is based on solving equations which describe the energy conservation in partial differential forms of the components of the system.The differential equations were solved using the implicit finite-difference method, and the simulation is carried out using MATLAB program. In order to verify the proposed method, an experiment was conducted in variable ambient conditions and flow rates on a solar air collector with a flat plate galvanized iron absorber.The comparison between computed and measured results of outlet air temperature shows a satisfactory convergence. The simulation results are also verified with distinguished research results from literature.The results show that the V-corrugated collector has considerably superior thermal performance than the flat plate collector of about 21.64% for single-flow mode and 17.16% for counter-flow mode. Furthermore, the model shows that the efficiency of the double-flow mode is greater than the single-flow mode by 17.01% and 12.53%, respectively, for the flat plate and V-corrugated solar air heaters.

The experimental study focuses on investigating the aerodynamic flow structure and the characteristics over non-slender diamond wing having low sweep angle (Λ = 51°). The vortical flow on the surface of the non-slender diamond models was investigated using dye-flow visualization and a stereoscopic particle image velocimetry (SPIV) technique. The near-surface flow structure, topology, and the formation of the vortex breakdown over the wing were also studied by varying the angle of attack α within the range of 5° ≤ α ≤ 25°. Experimental analysis is composed of the time-averaged patterns of streamlines, contours of vorticity distributions, and stream-wise velocity components for interpreting flow physics. It was concluded that vortex breakdown occurred farther upstream from the trailing edge of the wing at low angle of attack. However, once the angle of attack increased, formation of the vortex breakdown occurs farther downstream. So the location of vortex breakdown moved to the apex of the wing as the angle of attack increases. And the flow over the wing was fully stalled when the angle reaches α = 25°.

The uses of microchannels provide a significant increase in the efficiency of compact heat exchangers and a significant improvement of the energy performance of systems. This paper presents an experimental analysis of a transitional flow of water steam condensation in microchannels with different diameters (100, 200, 300, and 400 μm) and the experimental study by the display of different flow regimes during condensation of water steam in a mini-channel. The goal is to make a characterization based on the image processing of different flow regimes occurring during condensation. An analysis of condensation cycles for flows that identified a repetitive manner is made. A thermal performance can be achieved using a reduced diameter of the order of micrometers.

A desert is characterized by high temperatures and sand storms, but despite the inconveniences, it remains the ideal region for solar installations. In the operation of a thermal solar tower, the knowledge of wind loads is important for sizing the heliostats in order to have good performances. These loads can be calculated using mathematical equations based on several parameters: the air density, wind velocity, the aspect ratio of the mirror (height/width) and the tower height coefficient. Based on the measurement data of wind velocity and the density of air, a numerical simulation of wind profile was performed on heliostats with different pylon heights, with mirror areas of 1m2 and a mirror aspect ratio of 1. These measurement data were taken from the meteorological station installed in Ghardaïa, Algeria. The main aim of this work is to find a mathematical correlation between the wind loads and the height pylon of the heliostat.

This work presents an experimental study of nonpremixed combustion, which aims to study the following: first the effects of the change in the percentage of oxygen, second the effects of the change in the overall equivalence ratio, and finally the effects of the variation of the injectors’ spacing, on the stability and the length of the flame.On the one hand, results show that the shape of the low flame is not symmetrical and that the attachment flame is shown on the side of the injection of oxygen. On the other hand, the flame length increases with an increase in wealth, with an increase in the percentage of oxygen, and with an increase in the spacing between the nozzles of the burner.

In this paper, a numerical study of coupled heat and mass transfers during the absorption and desorption processes of metal-hydrogen reactor (LaNi5−H2) is presented. A theoretical model describing the dynamic behavior of the reactor is developed and solved by the lattice Boltzmann method (LBM) given its simple implementation on a computer and high performance.The numerical simulation was used to present the temporal evolution of the temperature and the hydrogen mass absorbed within the reactor and to compare two configurations of metal-hydrogen reactor (with and without heat exchanger).

The first objective of this work is to study the flow evolution through a gamma-type Stirling engine by a numerical tool. The quasi-steady model formulated by Urieli and Berchowitz (Stirling cycle engine analysis. Techno House, Radcliffe Way, Bristol ISBN 0-85274-435-8 (A. Hilger, Bristol), 1984) was adopted. The thermal and the mechanical losses generated in a Stirling engine are added to the model. The pressure drop through the heat exchangers was calculated to assess the friction factor value. The parameters characterizing the flow in the engine are calculated (Nusselt, Reynolds, and Darcy friction factor) and discussed. The proposed model will be used to estimate these factors. In a second part, the correlations proposed in the literature (Tanaka 1993; Gedeon and Wood Oscillating-flow regenerator test rig: hardware and theory with derived correlations for screens and felts. NASA CR-198442, 1996) to study the turbulent flow are applied to the gamma-type Stirling engine to proceed to the best theoretical results that better describe the experimental ones.

Crude petroleum migration as the laminar flow in incompressible fluids and hydrocarbon classification is the principal study to crude petroleum flow rate related to Darcy’s Law and Hagen–Poiseuille Law in mass of flow rates by numerical computation. Crude petroleum classification is apprehensive for the migration from a petroleum reservoir to underground surface. A case study of this secondary migration is generated in Fang Basin, the northern part of Thailand. Chemical characteristics of hydrocarbon by Fourier transform infrared (FT-IR) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy can be classified as the paraffinic, intermediate paraffinic, aromatic, and asphaltic classes, in the ratio of 5:10:4:1, respectively. For Fang crude oil, the API gravity (American Petroleum Institute’s gravity) and viscosity-gravity constant are evaluated in the range of 21.46–34.51° and 0.85–0.92, respectively. These properties signify two types of paraffinic and intermediate classes. Consequently, its hydrocarbon classification is indicated as the paraffinic, intermediate, aromatic, and asphaltic classes. Petroleum migration is applied for Darcy’s Law and Hagen–Poiseuille Law to the volumetric flow rates and mass of flow rate. The volumetric flow rates implicate to the petroleum migration which refers to the hydrocarbon classification. These specify possibility of migration with the mass flow of hydrocarbon class. The mathematical model is applied to separate zones of hydrocarbon class. The relationship of their volumetric flow rates can predict and estimate the combination of the volumetric flow rates as a function of mass of flow rates with three classifications (conventional crude oil, heavy crude oil, bitumen). Fang crude petroleum related to all information notifies that the crude petroleum classes are bitumen to heavy crude oil. Fang crude oil can be predicted a trend of the migration zones of heavy crude oil, heavy crude oil–bitumen, and bitumen zone by mathematical model. Thus, evaluation results reveal that the slow volumetric flow rates relate to pressure depths, petroleum migration, and crude petroleum classification.

According to the literature review, we can conclude that the study of the hydrodynamic structure flow around Savonius hydroturbine is very interesting. In the present paper, we are interested in studying the hydrodynamic structure flow around Savonius rotor. The remaining was organized as follows: Sect. 2 defined and discussed the description of our problem. Section 3, however, was devoted to numerical approach. In Sect. 4, our numerical results were detailed, and then we compared them with our experimental results. Finally, our conclusions were drawn in Sect. 5.

In this study, hydrodynamic design of a tunnel submarine (with a special form), moving in tunnel and in fixed or moving fluid media, has been investigated. Hydrodynamic design of a tunnel submarine and its system have been studied by dimensional analysis as analytically. Firstly, the paper focuses on the dimensionless parameters that govern the event, to find the independent variable. Secondly, law of resistance effect on a submarine and the pushing force produced by the propeller, and similarity condition for these two, has been obtained. Mathematical model of the tunnel submarine has been formulated. It has been found that resistance coefficient of tunnel submarine depends on Re, Eu, d/D, D₀/D, D/L, and U∞/V and trust of tunnel submarine depends on these as well as J’, V/V_a progress number.

Wind turbines usually operate in an unsteady flow environment. Therefore, the blade element forces vary with time and position of the blade and are influenced by the ambient turbulence, the blade vibratory motions, the control inputs, and the skewed flow. Thus, many methods of operation control are implemented in the new design of horizontal axis wind turbines such as the pitch control, the pitch power control, the passive stall power control, and the active power control (Burton et al. 2001).

Humidifiers are widely used in several domains such as water desalination by humidification–dehumidification, cooling towers, air conditioning, etc.

The hydrogen economy is a proposed scheme and technique of delivering energy using hydrogen. The hydrogen economy is committed to eliminate all of the problems that the fossil fuel economy creates. The advantages of the hydrogen economy consist of (Marban and Valdes-Solis 2007): (i) the elimination of pollution caused by fossil fuels, since the conversion technologies of hydrogen into energy are completely clean; (ii) the elimination of greenhouse gases, if hydrogen is produced using clean energy sources; and (iii) distributed production as hydrogen can be produced almost anywhere worldwide. However, the hydrogen economy faces several technological barriers before implementation such as the storage issues. The hydrogen storage in gaseous or liquid form presents serious safety concerns and requires high-energy input. The hydrogen storage in solid form, namely, reversible metal hydrides, is much safer and requires low-pressure conditions. Research on the design and performance optimization of the metal hydride tanks (MHT for short) is essential for the efficient operation of corresponding systems, thus considerable efforts are made in that regard.

In this paper, a study of laminar flows based on lattice Boltzmann method (LBM) is presented. Numerical investigations of flow dynamics and its heat transfer at a backward-facing step were performed. We have considered an imposed temperature on system walls and chosen a convective exchange mode. The lattice Boltzmann method (LBM) was used to perform the modeling. This method is based on direct simulation at the macroscopic level of the fluid particle evolution. The influence of Reynolds number on the flow and on the temperature distribution was studied. The dynamic study of the structure of the flow at a backward-facing step allowed us to clarify its main characteristics: shear layer, mixed layer, recirculation, separation-reattachment, and the interaction between the mixture layer and the flow caused by the step. The results show the temperature oscillation distribution at a backward-facing step. This study will then give an initial appraisal of the influence of the atmosphere on airplane wings and plays a very important role in the interpretation of the pollutant dispersion mechanism at the urban scale.

This work is an experimental investigation on oscillatory rotational flows with relatively high modulation frequencies and amplitudes. Two principal flow protocols have been defined and studied. The first one corresponds to advancing, stopped inner cylinder of a Couette-Taylor system with non-zero mean velocity, while the second protocol corresponds to the case where the inner cylinder oscillates harmonically (in time) clockwise and counterclockwise with non-zero mean velocity, i.e. it advances then moves back then advances again. According to the protocol, reversing or non-reversing Taylor vortex flows (RTVF or NRTVF) have been detected. Corresponding mass transfer and wall shear rate time evolutions strongly depend on modulation frequency and amplitude. If the oscillation amplitude is large enough, it can destabilize the laminar Couette flow; Taylor vortices appear even if the maximum oscillatory Taylor number is lesser than the critical steady rotational one (Ta_{oscillatory maximum} < Ta_{critical steady}). Mass transfer evolution has a sinusoidal evolution and still positive at high frequencies and high amplitudes bigger than the unit. The vortices direction can be deduced from the sign of the instantaneous wall shear rate time evolution. The presence of RTVF or NRTVF is dependent on oscillation amplitude. High modulation amplitude gives to vortices sufficient time to follow the direction of the inner cylinder (RTVF) despite the relatively high frequency which seems to be not enough to have NRTVF.

Boundary layer separation on the upper surface of a NACA0012 airfoil at low Reynolds number is numerically investigated. The governing equations are discretized with finite volume method. Second-order Adam-Bashforth and central difference schemes are used for time and space discretization. The boundary layer separation is examined through the velocity profiles, the skin friction distribution, and the flow structure. Beyond an angle of attack of 8°, a small separation region is detected near the trailing edge of the airfoil. As the angle of attack increases, the separation region grows up and moves toward the leading edge. The negative effect of separation on the aerodynamic performance can be seen clearly on the lift and drag distribution as function of the angle of attack. As the separation grows up, the rate of the lift coefficient decreases and the drag coefficient exhibits a substantial increase.

The Taylor-Couette flow is an axisymmetric, sheared, and azimuthal flow. It holds a primary site in the history of fluid dynamics. Several works have been devoted to study this problem. Despite the fact that it is very old, the problem of Taylor-Couette flow has received renewed interests in the past years.This renaissance is due to its high instability and the fact that it is particularly favorable to the rigorous mathematical analysis due to infinitesimal disturbances.The goal of this work is to provide an experimental study characterizing the Taylor-Couette instabilities in terms of interactions between vortices and wall.An experimental setup with a rotating inner cylinder and a fixed external cylinder was performed to study the flow at the gap between these two latters. Different types of movements imposed on mobile inner cylinder are available: cylinder oscillating, abrupt, or gradual disturbance. An axial flow was superimposed on the main flow of the Couette-Taylor.A qualitative study is firstly presented consisting of the visualization of the flow with the aim to draw the topology of the developed instabilities. Thus the different flow regimes conditioned by the dimensionless Taylor number are defined. The effect of superposition of an axial flow is shown.Experimental PIV measurements are then devoted to characterize the unsteady dynamics of the Taylor-Couette flow. Velocity and vorticity are investigated, and Γ₂ criterion is used to locate the vortex.In the other hand, electrochemical method is used and synchronized with PIV technique to determine the velocity parietal gradient. This technique allowed studying the vortex-wall interaction using response of single and triple probe and PIV.

This paper presents an experimental investigation of Couette-Taylor system (CTS) characterized by a radius ratio η = 0.97 and an aspect ratio Γ = 150 to study the spatial distribution of instantaneous mass transfer and wall shear rates. Many electrochemical probes were used to measure the local and instantaneous diffusion limited current at different radial positions of the inner wall of the outer fixed cylinder. Two neighboring probes are spaced apart by an angle of 7° on the circumference of the inner wall of the outer cylinder of the CTS. The electrochemical solution used is a Ferri-Ferrocyanure of potassium with 2% of K₂SO₄ as supporting electrolyte, 40% of glycerin which delays the instabilities apparition, and 2% of Kalliroscope for vortices visualization. The local and instantaneous mass transfer was determined from the diffusion limited current using the Faraday law. The radial distribution of the azimuthal and instantaneous wall shear rate was determined using different approaches for different Taylor numbers. The results of these approaches are illustrated and discussed.

An experimental investigation is conducted to test the thermal behavior and characteristics of R134a clathrates with additives, as phase change materials (PCMs), for cooling applications, and their charging capabilities are analyzed and evaluated. The formation of refrigerant clathrates is investigated due to their potential use in active and in passive cooling applications such as in electronic and residential cooling. The PCMs are made using R134a clathrate and distilled water with different refrigerant proportions and five different additives. The main objective of using additives is to study their potential in enhancing the clathrate formation over a small temperature range under direct contact heat transfer. The PCMs are formed in glass tubes and their freezing onset and transformation time was recorded. The refrigerant R134a percentages of 25%, 30%, 35%, and 40% are used to form clathrate. For the additives, ethanol, sodium chloride, magnesium nitrate hexahydrate, copper, and aluminum were used. The PCMs are formed using controllable constant temperature water. The times for initial onset until the times, where the clathrate structure does not change (end-set), are recorded at regular intervals. The low charging time shows that the PCMs require low energy input to change its phase, whereas more time shows PCM takes more energy to do so. A comparative study is conducted to compare the charging time for different PCMs using the suggested additives. R134a refrigerant clathrate without any additive is used as the base case for comparison. The results show that metal additives reduce the freezing time (charging time), and ethanol and sodium chloride increase it, while magnesium nitrate hexahydrate maintains it the same as that of the base case of PCM. It is also found that the freezing time depends not only on the thermal properties of the used additives but also on their ability to mix homogenously in the refrigerant clathrate mixture. Furthermore, some additives are considered to be very useful in enhancing the clathrate formation with a stabilized crystalline structure. Finally, the PCMs with high latent heats over narrow temperature ranges are desirable as they offer high energy density at uniform reasonable temperatures applicable for cooling applications.

In this paper a new analytical relation is presented to approximate pressure-flow rate relationship in terms of the dimensions of impeller and channel geometries for small regenerative turbine pumps (RTPs) using some simplifying assumptions. Numerical simulation of the pump is conducted to compare the results with that of the analytical one. It is demonstrated that the presented analytical relation approximates the P-Q curve of the real pump satisfactorily. Finally, sources of the deviation of the pump behavior from predictions made by the proposed analytical relations are examined and discussed.

There are two coefficients termed as “slip factor” and “shock loss (incidence) coefficient” that play an important role in performance and designing process of regenerative pumps. In this research, numerical simulation of regenerative pumps with incompressible flow and different dimensions of channel is conducted. A new technique is presented for accurate computation of “slip factor” and “shock loss coefficient” from numerical simulation of the pump. This technique is applicable to different sizes and models of regenerative pumps. By employing the presented technique, the influential coefficients and circulatory flow for two small regenerative pumps are examined quantitatively. Quantitative and accurate computation of shock loss coefficient and slip factor in regenerative pumps through numerical simulation is new to the literature. Finally, changes of the coefficients in a pump are examined as channel dimension changes.

This work addresses the recovery of a liquid effluent by thermal evaporation. It is a digestate of pig manure, rich in N, P, and K (Granier et al. 1995; Latimier et al. 1996; Levasseur, TECHNI 21(4):16–19, 1998). The effluent was subjected to anaerobic digestion and phase separation by centrifugation. Several recovery scenarios for the liquid phase of a waste with 2.3% DM (dry matter) are analyzed.Because of the high consumption of fossil energy in the world, we analyzed in this work the evaporation of this effluent using solar energy, in order to concentrate N, P, and K elements. The device consists of a stainless steel plate with a tilt angle of 30° and isn’t covered with glass. The liquid circulates as a film on the steel plate and is exposed to a 6000 W solar simulator.This work is divided into two primary parts. The first part is a thermophysical characterization of the effluent comparing to water. In the second part, evaporation tests with liquid effluent were performed. So, experimental tests will be valid by determining the equations of heat and mass balances on the plate and on the film (Bouchekima et al. 2001; Chen et al. 1986; Brau, Support de cours de convection pour 3 GCU, Insa de Lyon, département de Génie Civil et Urbanisme, 2006).Before starting tests, the plate is exposed to solar radiation until stabilization of its temperature. A validation of the temperature of the plate, depending on solar flux and temperature of air, in laminar regime, was performed (Huetz-Aubert and Sacadura 1981). We find that when the solar flux increases, the temperature of the plate increases. However, if solar flux is constant, the temperature of the plate decreases when the air temperature increases.The liquid circulates as a film flowing from the top of the plate. Local heat flux measurements, temperatures, and evaporated flow for input flow rate from 1 to 5 g/s are determined and compared with experimental results.

It is of interest to discuss the analogies between ELB and LBM with turbulence models. This paper addresses the issue of incorporation of the subgrid turbulence model in the lattice Boltzmann equation (LBE). A lattice Boltzmann solver is implemented using various techniques, and the performance will be discussed. The numerical validity of the codes is tested against known fluid flow solutions, and a visual representation of the fluid flow is created. The simulations include lattice Boltzmann method with subgrid model and single-relaxation-time (SRT), multiple-relaxation-time (MRT), and entropic collision models (ELBM). We explore the behavior and accuracy of the proposed models on lid-driven square cavity at Reynolds number up to 10.000. Our results clearly show that the LES-MRT model remains the most effective in terms of accuracy and stability. Also our results highlight the subgrid features of the ELBE.

The present chapter focuses on both thermoeconomic and electrochemical analyses of a hybrid photocatalytic reactor for hydrogen generation capable of substituting the electrical-driven hydrogen electrolysis subsystem of the Cu–Cl cycle. Several operating parameters, such as current density, reactor temperature, ambient temperature, and electrode distance, are varied to study their effects on hydrogen production rate, hydrogen production cost, and efficiencies. The results obtained from this study show that the voltage drops across the anolyte solution (sol 1), catholyte solution (sol 2), anode, cathode, and cation exchange membrane vary from 0.005 to 0.016 V, 0.004 to 0.013 V, 1.67 to 2.168 V, 0.18 to 0.22 V, and 0.06 to 0.19 V, respectively, with an increase in current density from 0.5 to 1.5 A/cm2. It is also observed that the hydrogen production rate and cost of hydrogen production increases from 1.28 to 1.47 L/s and 3.28 to 3.36 C$/kg, respectively, with a rise in the reactor temperature from 290 to 340 K. The energy and exergy analyses of the reactor show that the energy and exergy efficiencies of the hybrid photocatalytic hydrogen production reactor decrease from 5.74% to 4.54% and 5.11% to 4.04%, respectively, with an increase in current density.

Over the last few years, the energy demand for cooling systems is increasing; different solutions in fact have been proposed in order to minimize the energetic and environmental impact of this trend. In this direction, absorption cooling systems are recognized as a valid alternative to traditional vapor compression inverse cycles; waste heat from other systems can in fact be used as an efficient input instead of electrical energy. The opportunity to integrate LiBr absorption systems with a high-efficiency energy plant was studied; rejected heat from a municipal solid waste gasification plant integrated with solid oxide fuel cell and gas turbine, called IGSG (Integrated Gasification SOFC and GT), was in fact considered to feed absorption cooling units. Two different possible integrations of heat fluxes were investigated; variations of the most critical parameters have been studied and analyzed in order to evaluate plant features and find out critical working conditions.

In this work, the energy and exergy analysis of Tabriz power plant in Tabriz, Iran, is presented. The primary objectives of this paper are to analyze the system components separately and to identify and quantify the sites having largest energy and exergy losses at design mode at full load. It can be observed that although the heat loss in the condenser seems higher, the largest losses occur in the boiler, which has the highest exergy destruction. Also as long as the ambient temperature increases, the condenser pressure and heat loss also increase, resulting in reduced thermal efficiency. By reducing the temperature from 35 °C to −10 °C, plant thermal efficiency is increased by 1.38%.

The first law of thermodynamics or energy conservation principle is a good tool for thermodynamical processes. By using exergetic analysis of thermodynamical processes which are based on the combination of first and second laws of thermodynamics, we can obtain more information. The main purpose of using exergetic analysis is the better usage of energy resources. This analysis gives better understanding about electric power generation cycles by using availability principle. In this survey, Tabriz power plant with 368 MW capacity has been studied, and then after energetic and exergetic analysis, components which have more losses or less efficiency have been determined in the cycle, and afterward, their need for optimization has been introduced. Then, power plant behavior in load variations has been examined too. The results show that first- and second-law-based efficiencies in nominal load are 40.12% and 37.62%, and upon energetic analysis of cycle, condenser and boiler have the most losses with 420.440 and 192.902 MW, respectively. On the other hand, exergetic analysis shows that boiler, turbine, and condenser have the most exergy destruction with load change from 100% to 50%. In this study, we found that energetic and exergetic efficiencies of cycle had remarkable reductions as the amount of reductions of the first- and second-law-based efficiencies changed from 40.12% and 37.62% to 34.61% and 32.46%, respectively.

Mini class gas turbine engines are today used for small UAVs, cogeneration applications, and hybrid electric vehicle applications. In this paper, exergetic assessment of an indigenous mini class gas turbine engine is investigated. This engine is classified as mini class gas turbine where it differs from similar class engines in two ways, including closed loop lubrication system and bearing damping. A great amount of bench testing studies with required extensive instrumentation were also performed to demonstrate the suitability of this technology. Consequently, an approach in order to evaluate test data parameters for the exergetic performance is presented for mini class gas turbine engines used for small experimental planes and small-scale UAVs by applying the energy and exergy analyses to the engine. Hence, exergetic efficiency, improvement potentials, exergy destruction rates, relative exergy destructions, fuel depletion ratios, productivity lacks, and fuel and product exergy factors are calculated for the engine taking into account only dry air. This study shows that main exergy destruction for a typical gas turbine occurs in the combustion chamber. Exergetic efficiencies for centrifugal compressor, combustion chamber, and high-pressure turbine are found to be as 74.04%, 56.06%, and 98.98%, respectively. Finally, it was flight tested several times on small-scale UAVs and small experimental aircrafts with success.

In order to make the storage mode in a metal-hydrogen reactor (LaNi₅-H₂) more cost competitive in terms of thermal energy, we propose in this study to store the released heat during hydrogen absorption (exothermic) by using a phase change material (PCM), for recovering it during desorption process. A transient two-dimensional mathematical model to predict the heat and mass transfer in the hydride bed and the phase change medium is presented and solved numerically by the unstructured control volume finite element method (CVFEM). For this model, the liquid fraction in the PCM was described by an analytic approximation of the Heaviside step function which, to the knowledge of the authors, is applied for the first time to study phase change problems. The validation of the numerical model has been performed by comparison with experimental data, and several numerical simulations were carried out to evaluate the effect of the thermal conductivity of PCM on the dynamic behavior of hydriding and the melting processes.

A hybrid (solar-hydrogen) renewable energy system consisting of photovoltaic (PV) panels, proton exchange membrane (PEM) fuel cells, PEM-based electrolyzers, and hydrogen storage has been investigated for a stand-alone application, which was established for the emergency room of Kecioren Training and Research Hospital in Ankara, Turkey. A complete model of the hybrid renewable energy system has been developed using TRNSYS. The main goal of the study is to meet the electrical power demand of the emergency room without any shortage for a complete year in an emergency blackout condition. The emergency room has a peak electrical load of 5 kW and a yearly load of 37.23 MWh. The PV panels are mounted on a tiltable platform to improve the performance of the system. The total area of the PV panels is 300 m2, and the PEM fuel cell capacity is 5 kW. The hydrogen storage pressure is 55 bars with the capacity of 45 m3. Energy and exergy analysis is performed for the hydrogen cycle of the system for a complete year. Overall energy and exergy efficiencies of the hydrogen cycle of the system are calculated as 4.06% and 4.25%, respectively.

In large air compressor installations consisting of multiple compressors operating continuously, even a small reduction in the inlet air temperature can improve the plant efficiency. Exergy efficiency is more rational than energy efficiency, and exergy analysis is more helpful than energy analysis for locating and evaluating available energy-saving potentials, identifying opportunities for improvements in system design, and establishing cost-effective system maintenance programs. When exergy analysis is performed on a system, thermodynamic imperfections can be quantified as exergy destruction, which represent losses in energy quality. In the present study, a thermodynamic analysis is made on the inlet air cooling system employed in a centrifugal compressor. Exergy input rate, exergy output rate, exergy loss rate, exergy destruction rate, and exergy efficiency were calculated with five different dead state temperatures and five different dead state relative humidities. Sustainability assessment is done by estimating the sustainability based on exergy efficiency.

Environmental pollution, global warming, and depletion of fossil fuels compel radical changes in automotive engine technologies in directions that offer both the potential for achieving near-zero emissions of pollutants and greenhouse gases and a diversification of the transport fuel system away from its present exclusive dependence on fossil fuels. Hydrogen-fueled vehicles can be an environment-friendly alternative. Composite high-pressure tanks can be used for storage of hydrogen gas on board road vehicles. Durability and safety of the fuel tanks are the important concerns involved. In this paper a numerical model is developed for the analysis of the cyclic fast charging and discharging process of a high-pressure hydrogen gas tank to determine the effect on tank wall temperature. The flow is considered as compressible, viscous, unsteady and turbulent. Axisymmetric, time-dependent, Navier-Stokes equations were solved with the two-equation realizable k-ε turbulent model for turbulent momentum closure. Redlich-Kwong real gas equation was used for density computations. The numerical model is of relevance to the design of high-pressure tanks for durability and safety, primarily with regard to the wall configuration.

To enhance the air bootoming cycle's efficiency (ABC), the integration of pulse combustor in ABC configurations is proposed. Two different configurations for pulse combustor incorporation in ABC are recommended including pulse combustor replacing the topping cycle combustion chamber and pulse combustor integration as a supplementary firing in the bottoming cycle. Sensitivity analysis is performed by controlling different design variables and investigating their effects on both thermal efficiency and net specific work output. Moreover, a detailed thermodynamic optimization is performed to achieve the highest power enhancement resulting from the implementation of pulse combustion for cycle configuration. Integration of pulse combustor in the topping cycle can improve the plant efficiency to 50.8% whereas the maximum possible ABC’s efficiency is about 43.6%. Finally, the integration of a pulse combustor as a supplementary firing in the bottoming cycle would enhance the overall plant efficiency to reach about 41.8%.

A multi-objective optimization method of cogeneration of power and heat in a combined gas turbine and organic Rankine cycle (ORC) is conducted to achieve the best system design parameters from both thermodynamic and economic aspects by utilizing nondominated sorting genetic algorithm-II (NSGA-II). Exergy efficiency and total cost rate of the system have been considered as objective functions. The cogeneration system consists of a gas turbine (GT) and an organic Rankine cycle (ORC) in which the two cycles are connected through a single-pressure heat recovery steam generator (HRSG). In order to optimize the system, air compressor pressure ratio, air compressor isentropic efficiency, air preheater outlet temperature, turbine inlet temperature, isentropic efficiency of the gas turbine, pinch point temperature of HRSG, pinch point temperature of evaporator, evaporator temperature, and condenser temperature have been selected as decision variables. Optimization results indicate that exergy efficiency of the cycle increases from 51.41% at base case to 55.6% while more than 9.15% reduction is achieved in the total cost rate of the cycle. Also by applying multi-objective optimization, the exergo-economic factor has reached from 10.68 to 27.40.

This chapter presents energy, exergy, and environmental analysis of 100 MW intercooled gas turbine engine inspired from LMS 100 GE, a state-of-the-art aeroderivative gas turbine engine, which offers the highest simple-cycle thermal efficiency today. The proposed models have been modeled using a software package called IPSEpro and validated with manufacturer’s published data. In fact, most gas turbine engines are designed using energetic performance criteria based on the first law of thermodynamics. Exergetic performance criteria is based on the first and second laws of thermodynamics (Yilmazoğlu and Amirabedin, 2011), which when combined are considered more efficient in energy-resource use owing to the way in which locations, magnitudes, and types of wastes and losses in the system are determined. The performance of gas turbine engine was investigated using different loads and ambient temperatures on two configurations. The first include intercooling gas turbine (ICGT) system (Case I), whereas the second is simple-cycle gas turbine (SCGT) engine (Case II). Results show that intercooler system improves gas turbine performance, whereas they have negative impact on combustion chamber due to reduction in inlet temperatures. Load reduction causes an adverse effect on performance, whereas ambient temperature reduction causes the reverse. From an environmental perspective, the present study has developed a new exergetic–environmental indicator to relate the efficiency with nature of exhaust gases in order to measure environmental impacts and increase the lifespan of energy resources. All environmental indicators show ICGT as more appropriate to environment in comparison to SCGT. Furthermore, it achieved the lowest level of CO₂ emissions per KWh.

Experimental investigations and theoretical analysis of a commercial diffusion-absorption refrigerator are presented in this paper. During the tests, the temperature at 14 locations – at the inlet and outlet of every component of the machine – as well as the cabinet and ambient temperature is measured. The tests are repeated for various electric power inputs to the refrigerator. The steady-state cooling capacity of the machine and its coefficient of performance, COP, are evaluated. The experimental data is used to validate a theoretical simulation model of the machine developed using the flow-sheeting software HYSYS of AspenTech.

Exergoeconomics is the branch of engineering that combines exergy analysis and economic principles to provide the system designer or operator with information not available through conventional energy analysis and economic evaluations but crucial to the design and operation of a cost-effective system (Bejan et al., Thermal design and optimization, Wiley, 1996). In fact, it provides extra information than exergy analysis for the design of cost-effective energy systems, as an exergy-aided cost-reduction method, by associating costs with exergy losses. It aims to calculate separately the costs of each product generated by a system having more than one product, to understand the cost-formation process and the flow of costs in the system, to optimize specific variables in a single component, or to optimize the overall system (Abusoglu and Kanoglu, Renaw Sust Energy Rev 13:2295–2308, 2009). Many examples of exergoeconomic approaches were found in literature and can be divided into two classes: (1) the exergoeconomic accounting methods that aim at the costing of product streams, the evaluation of components and systems, and the iterative optimization of energy systems; (2) the calculus approaches have as a goal the optimization of the overall system and the calculation of marginal costs (Atmaca and Yumrutas, Energy Convers Manag 79:790–798, 2014a; Atmaca and Yumrutas, Energy Convers Manag 79:799–808, 2014b).The basic elements of exergoeconomics are presented in this work including cost balances, means for costing exergy transfers, and exergoeconomic variables used for the evaluation and optimization of a thermal or chemical system.

In this paper, energy and exergy analyses are performed on an aircraft air cycle machine. Air cycle machine is essential to ventilate aircraft cabin during commercial flights. Exergy destruction rates and energy parameters of each component are investigated at a designated aircraft cruise altitude which is 10,789 meters and ambient air that is −55 °C. The thermodynamic parameters used here to obtain the results are real ones from actual devices. Exergy flow supplied to the air cycle machine is found as 235.392 kW. Exergy destruction rate of primary heat exchanger is calculated as 33.839 kW. Exergy destruction rate of turbine, compressor, and secondary heat exchanger section is calculated to be 55.65 kW.

Energy efficiency of a building has become a major requirement since the building sector produces 40%–50% of the global greenhouse gas emissions. This can be achieved by improving building’s performance through energy savings, by adopting energy-efficient technologies and by reducing CO₂ emissions. There exist several technologies with less or no environmental impact that can be used to reduce energy consumption of the buildings. Earth pipe cooling system is one of them, which works with a long buried pipe with one end for intaking air and the other end for providing air cooled by soil to the building. It is an approach for cooling a room in a passive process without using any habitual mechanical unit. The paper investigates the thermal performance of a horizontal earth pipe cooling system in a hot and humid subtropical climatic zone in Queensland, Australia. An integrated numerical model for the horizontal earth pipe cooling system and the room (or building) was developed using ANSYS Fluent to measure the thermal performance of the system. The impact of air temperature, soil temperature, air velocity and relative humidity on room cooling performance has also been assessed. As the soil temperature was below the outdoor minimum temperature during the peak warming hours of the day, it worked as an effective heat sink to cool the room. Both experimental and numerical results showed a temperature reduction of 1.11 °C in the room utilizing horizontal earth pipe cooling system which will assist to save the energy cost in the buildings.

This paper is a contribution to the waste heat recovery in a diammonium phosphate production plant. Such plant is made of sulfuric acid, phosphoric acid, and diammonium phosphate production units.The production of sulfuric acid by the contact process results in a significant waste of thermal energy associated with acid cooling by seawater. Such waste can exceed 30 MW for a production of 1500 tons/day. Furthermore, this process rejects about 150 t/h of gas at a temperature of 70 °C.In this paper three systems are presented for waste heat recovery in the studied plant. First, a hot water loop is designed for the production of low-pressure steam. The thermal energy to be used in this loop comes from the sulfuric acid streams that need to be cooled in the process. Then, low-pressure steam is substituted by sulfuric acid for the concentration of the phosphoric acid produced in the same plant. Finally, a pre-concentration of the phosphoric acid is considered by direct contact with the rejected hot gases in a spray column.A techno-economic study was conducted to evaluate the profitability of the proposed systems.

This comparative study focuses on energy, exergy, and environmental analyses of parabolic trough solar thermal power plant working on four different fluids. Two of the four fluids used are nanofluids, aluminum oxide (Al₂O₃) and ferrous oxide (Fe₂O₃). The other two fluids are glycerol and Therminol 66 which are oils. Two operating parameters, ambient temperature (T₀) and solar irradiance (G_b), are varied to observe their effect on the heat rate produced, net power produced, energy efficiency, exergy efficiency, and environmental impact of parabolic trough solar thermal power plant (PTSTPP). The results obtained show that the energy and exergy efficiencies increase by increasing the solar irradiance. The energy efficiency of parabolic trough solar collector (PTSC) running on four different fluids, aluminum oxide, ferrous oxide, glycerol, and therminol, increases from 52.53% to 79.29%, 52.2% to 78.65%, 52.53% to 79.15%, and 53.17% to 80.13%, respectively, with increase in solar irradiance from 400 W/m2 to 1100 W/m2. The exergy efficiency of PTSC for the tested fluids increases from 24.68% to 41.91%, 24.64% to 42.3%, 24.67% to 42%, and 24.72% to 41.33%, respectively, by increasing the solar irradiance. The net power produced by parabolic trough solar thermal power plant (PTSTPP) is found to be increasing from 76.55 to 81.51 kW, 74.25 to 79.17 kW, 76.08 to 81.03 kW, and 100.2 to 106.5 kW, respectively, with increase in ambient temperature from 275 to 325 K. The exergo-environmental impact index for the four fluids decreases from 3.379 to 3.072, 3.419 to 3.102, 3.388 to 3.079, and 2.435 to 2.202, respectively, by increasing the ambient temperature from 275 K to 325 K. It was observed that the use of nanofluid enhances the net power output of the solar thermal power plant. The analyses also show that increase in ambient temperature and solar irradiance considerably affects the exergetic efficiency and environmental impact of parabolic trough solar thermal power plant.

The scope of this work is to apply exergetic simulation and performance investigation of 1–1 shell and tube heat exchanger using COMSOL Multiphysics simulation programme. Applying simulation to energy-intensive systems has great importance before the design phase as it gives the engineers the possibility to avoid energy loss and increase efficiency before constructing the device and experimenting it. Since the modelling and optimization is essential for better performance in thermal systems by including detailed computational fluid dynamics (CFD) and multiphysics, a broad parametric study is applied considering the operating parameters of inlet flow rates and temperatures of the fluids. Three-dimensional (3D) results for temperature, velocity and pressure profile for each case are determined and evaluated in a finely meshed structure. The results showed that the exergy destruction is minimized in high shell-side velocity temperature and low tube-side velocity temperature.

In this study, parametric investigation of a direct formic acid fuel cell (DFAFC) system for evaluating the thermodynamic performance is conducted, including evaluation of a broad set of operating parameters and wide value ranges for them. The fuel cell system is modelled and a parametric model is developed by using MATLAB. The auxiliary system components are included into the model for consideration. The effect of the operating parameters such as temperature, pressure, membrane thickness, current density and anode-cathode stoichiometry on the system is evaluated, to predict the performance as close to real cases as possible. It is found that increasing the temperature increases the efficiency of the direct formic acid fuel cell system, followed by low-pressure and high-reference environment temperatures. The maximum exergetic efficiency achieved by detailed parametric investigation is 24%, where power production is 10 kW.

This article first gives a brief review of heat engines designed for terrestrial transportation since the 1900s. We then outline the main developments in the state of the art and knowledge about internal combustion engines, focusing on the increasingly stringent pollution constraints imposed since the 1990s. The general concept of high-energy performance machines is analyzed from the energy and public health point of view and illustrated with typical examples of clean energy production and zero emissions. The article concludes with some perspectives for the emergence of an economic model that could be applied to land-based transport systems in the framework of energy transition by 2030.

Two different multi-objective optimization scenarios are carried out to determine the best design parameters of a bottoming cycle of a trigeneration system with a HCCI engine as prime mover. For the first scenario, the objective functions which are utilized in the optimization study are exergy efficiency and the sum of the unit costs of the system products. The system cost criteria is minimized, while the cycle exergy efficiency is maximized using an evolutionary algorithm. Exergy efficiency increases about 16.34%, and the reduction in the unit costs of the system products is about 10%. However, it is found that cooling capacity of the system is reduced about 83%. For the second scenario, the objective functions are considered to be the sum of the unit costs of the system products, net power generation, and exergy flow rate of refrigeration output. Employing the second scenario improves both power generation and cooling capacity of the system. The increase in exergy efficiency is about 5.61%. These are achieved with even a slight reduction in the system cost criteria.

This paper presents a bootstrap aggregated neural network-based strategy for the modelling and optimisation of crude distillation unit incorporating the second law of thermodynamics. Exergy analysis pinpoints the location and magnitude of the losses and is a tool for determining how efficient a process is. Exergy analysis of processes gives insights into the overall energy use evaluation of the process, potentials for efficient energy use of such processes can then be identified, and energy-saving measures of the processes can be suggested. The focus is to improve the exergy efficiency of the crude distillation and hence reduce the energy consumption. To overcome the difficulties in developing detailed mechanistic models, data-driven models such as artificial neural network (ANN) models can be utilised. Real-time optimisation of distillation columns is made feasible by using ANN models which can be quickly developed from process operation data. To enhance the reliability of ANN models, bootstrap aggregated neural network (BANN) is used in this study. A further advantage of BANN is that model prediction confidence bounds can be obtained. BANN models for exergy efficiency and product qualities are developed from simulated process operation data and are used to maximise exergy efficiency while satisfying product quality constraints. The standard error of the individual neural network predictions is taken as the indication of model prediction reliability and is incorporated in the optimisation objective function. Application to a crude distillation system (comprising of ADU and VDU) shows good improvement in the exergy efficiency of the unit and no additional costs of equipments. A further analysis was to investigate the effects of preflash units on the exergy efficiency of the ADU and VDU. The analysis gives realistic and promising results. The method could be applicable in determining feasible and energy-efficient operating and design conditions for the crude distillation unit.

This study addresses the optimal design of solar-assisted absorption cooling systems and corresponding operating conditions considering total cost and environmental concerns. The basic idea of an absorption cooling system is to replace the electricity consumed by the compressor used in a conventional cooling system by a thermally driven absorption-desorption system that operates with a suitable fluid pair consisting of one refrigerant and one absorbent.The environmental performance of the solar cooling system was determined using the life cycle assessment (LCA) methodology. The Eco-indicator 99 metric along with its subdamage categories was also used in calculating the environmental impacts. The problem involves two different systems: absorption cycle and solar collector system. The model was written before using the generalized algebraic modelling system (GAMS). The same model was used to integrate a broader environmental analysis. Additionally, in the scope of this thesis, the problem related to the absorption cycle itself was introduced in MATLAB and ASPEN Plus programs, and the optimization was performed. Generalized reduced gradient (GRG) method was selected for the solution in GAMS. In MATLAB, the problem was solved using genetic algorithm.

Energy is the most important driving force for the social and economical development of a country. Nowadays, especially energy-sensitive industries such as refining and petrochemical industries are targeting to recover maximum amount of energy by applying to process integration. The energy consumed in industrial processes is typically used for heating and cooling purposes. Efficient design of heating and cooling systems in an industry is therefore vital. In the present energy crisis scenario all over the world, the purpose of any process design is to maximize the process to process heat recovery and to minimize the utility requirements. An appropriate HEN is required for the comparison of maximum energy recovery or minimum energy requirement (MER).In this study, the exergetic evaluation of heat exchanger network (HEN) in a raw petroleum cracking unit is to be performed. The pinch analysis and second law insight analysis are applied on the existing HEN of the raw petroleum cracking unit. Then the exergy loss and exergetic efficiencies of networks are calculated. It is seen that exergetic loss of second law insight HEN is lower than the pinch HEN.

In this study, the gas turbine cycle of Ovaakca power plant that is located in Bursa, Turkey was analysed. The aim of the study is to determine the use of an ice thermal energy storage system for the 239 MW-powered gas turbine cycle. The performance of the system was investigated for full-load conditions. Energy and exergy analysis were performed by using last decade’s meteorological weather data. The results showed that utilizing an ice thermal energy storage system can boost the net power up to 12.60%.

The climate condition affects the performance of the combined-cycle power plants. The efficiency of the combined cycle is significantly influenced by the temperature, pressure and humidity of the air. When the ambient air temperature increases, the density of the air decreases, and it leads to a reduction of power generated by the gas turbine. In this work, the energy and exergy analysis of a commercial gas turbine, with inlet air cooling, was performed. The effects of fogging system on gas-turbine performance studied. For this aim, the energy and exergy balances were obtained for each piece of equipment. Calculations have been made for four different cases for the regarded gas turbine system. Furthermore, exergetic efficiency, exergy destruction rates and improvement potentials were obtained, and the results of the study demonstrated graphically. It is concluded that the net power output of the gas turbine system increased at lower inlet temperatures and exergy destruction rates occurred from highest to lowest as combustion chamber (CC), gas turbine (GT) and air compressor (AC), respectively.

This research paper mainly deals with a thermodynamic modeling and exergy analysis of a hybrid energy system consisting of a solar PV/T panel, PEM electrolysis, a polymer fuel cell (PEMFC), and single-effect Li-Br absorption chiller. Hydrogen is produced in this cycle using the electricity generated by PV/T panel, and it is stored in storage for later use at night when there the sun is not available. Hence, this cycle can be used at all hours of day and night. Solar radiation intensity per year is obtained by climate data of the capital city of Iran, Tehran. The effects of fuel cell current density on system efficiency, work and heat, voltage of system, and exergy losses in each component are investigated. Also, the exergy efficiency and the total cost rate for the objective function were used in an optimization problem based on the genetic algorithm. The results show that efficiency of energy and exergy of the cycle are 36% and 29%, respectively.

In this paper, the effect of ignition timing on exergy has been investigated. At the first step, 3D-scheme numerical simulation of a complete engine cycle including combustion process has been taken to account for S81 engine geometry. 3D computational modeling process requires complete simulation of flow field in a fine mesh geometry which includes combustion modeling and dynamic mesh process in region of valve and piston movement surfaces. According to the aforementioned reasons, numerical simulation is assumed to be a highly expensive process which requires high CPU process and CPU time costs. To reduce the cost of the solution, numerical simulation of cold flow (without combustion) is accomplished for motoring cycle on the first step. The results of flow field are taken to account for combustion stage as initial condition. Numerical results are validated using experimental data of FEV institute for current engine with known initial and boundary conditions. The exergies of heat transfer, total work, fuel, and irreversibility of different engine revolutions are studied for different ignition timings, and the results indicate that while the crack angle in which ignition occurs comes closer to the top dead center position, all exergies increase as the consequences.

The performance of a CO₂ transcritical hydrogen production/refrigeration cogeneration cycle is investigated and optimized with an economic approach. Exergy and exergoeconomic models are developed in order to investigate the thermodynamic performance of the cycle and assess the unit cost of the cycle products. In this study, hydrogen exergy efficiency optimal design (HEEOD), refrigeration power optimal design (RPOD), and cost optimal design (COD) are considered for analysis and optimization. According to recent parametric studies, boiler and turbine inlet temperature, turbine inlet pressure, condensation, and LNG inlet temperature significantly affect the unit cost of products. The results show that the sum of the unit cost of products (SUCP) is obtained through exergoeconomic optimization; in the three cases of HEEOD, RPOD, and COD, it is, respectively, 24.2%, 24%, and 32.7% lower than the base case. It was observed that the SUCP is decreased by 8.5% when hydrogen production rate is decreased from 1.811 lit/s in HEEOD case to 1.756 lit/s in COD case. The evaluation of exergy destruction, for each component of system in three cases of optimization, demonstrates in which the condenser has the highest exergy destruction due to high-temperature difference; therefore, the exergy destruction of condenser in COD case is the lowest among the three other states. The results indicate the total exergy destruction and the investment cost rates in the RPOD case are higher than any other cases.

This study deals with a thermodynamic analysis of a combined cycle of 400 MW provided with a system of steam injection in the combustion chamber, two steam extractions from the steam turbine, two open feedwater heaters, and a system of air combustion cooling.This study describes the influence of external and internal parameters on the cycle performance. The power plant is constituted by a Gas Turbine cycle with steam injection and compressed air cooling usystems, a Eteam Turbine cycle with two extractions and a Heat Recovery Steam Generator.A numerical simulation of the combined cycle with Engineering Equation Solver software is realized by considering operational range of variables such as compression ratio, air excess, steam injection rate, steam extraction pressure, condensation pressure, and other parameters. In this chapter, influences on the overall cycle performance are analyzed.The goal of this study is to describe the change on the cycle performance and efficiency with ambient temperature influence and with pressure extraction.

CO₂ emission criteria have different approach for many countries. These approaches are not sufficient to define regarding global effect based on the loads of emission. Although depending on the extent of the IPCC criteria (Intergovernmental Panel on Climate Change) and particularly high entropy production, fossil energy sources are rapidly increasing equivalent CO₂ emissions. For identifying of the emission potentials and strategic approach correctly for national or international target, carbon metric method based on exergetic approach is developed particularly in the building sector. In this study, three different emission criteria considering examples of building taken references, isolation, non-isolated conditions and TS-825 standard, were examined depending on exergetic analysis for building dispersion of Turkey.According to analyses, differences among emission criteria were found significant value with reaching 90%. At the end of the study, some assessment and recommendations about benefits of carbon emissions metric and importance of the exergy concept for building analyses have been made.

During the past decade thermochemical and/or hybrid cycles using essentially heat (without/with some electricity) are preferred over conventional electrolysis where the electricity is the main energy input. Therefore, such cycles help significantly reduce the electrical work consumption by adapting some consecutive chemical reactions which utilize thermal energy at medium to low temperatures that can match with renewable and existing nuclear energy sources. The ideal magnesium-chlorine cycle consists of three steps, namely hydrolysis of MgCl2, chlorination of MgO, and electrolysis of HCl. In this particular study, we develop two newly proposed configurations to compare with the ideal version of this cycle. The first configuration uses an intermediate step through the hydrolysis reaction while a fourth step is introduced in the second configuration where HCl production is accomplished in dry form. Thermodynamic comparisons are carried out using energy and exergy analysis, and the four-step configuration practically shows the highest performance and can compete with the conventional splitting of water by electrolysis. In summary, the present options provide potential solutions for sustainable hydrogen production.

To utilize the exergy of solar and industrial exhaust heat, latent heat storage (LHS) using phase change materials (PCM) is quite attractive for its high heat storage capacity, constant-temperature of the heat supply, and repeatable utilization without degradation. In this article, general LHS technology is outlined first; then recent advances in the uses of LHS for high-temperature applications (over 100 °C) are discussed, with respect to each type of PCM (e.g., sugar alcohol, molten salt, and alloy). The prospects of future LHS technology are discussed regarding exergy.

Energy analysis assists in performance evaluation of a system, and exergy analysis not only results in performance but also diagnosis, identifies the strong and weak areas, reveals the scope for improvement, and suggests modifications for perfection. In current work, four energy systems have been selected and evaluated using exergy approach and identified the merits in exergy usage. The exergy evaluation methodology has been generated. The selected problems are (i) testing of heat exchanger (deaerator) locator in a power plant, (ii) optimum degree of steam injection in a combustion changer, (iii) comparison of two plant configurations, and (iv) study on working fluid choice. The exergy analysis results exited and novel finding, used in modifications and decision-making. The results of selected four problems are (i) new deaerator location, (ii) steam fuel ratio of 3, (iii) parallel arrangement of heat source with regenerator, and (iv) LiBr-water mixture in place of ammonia-water mixture.

Post-combustion CO₂ capture (PCC) is one of the strategic technologies identified to reduce emissions of greenhouse gases (GHG) in an existing power plant. CO₂ capture incurs serious energy penalty due to the energy use for solvent regeneration in the capture process and subsequent increase in cost of electricity. Reducing the energy/exergy use in the process can lead to a reduction in energy penalties. Beyond demonstrating this lower level of actual energy/exergy consumption, it is important to increase the efficiency of the CO₂ capture system. This study includes steady-state simulation and conventional and advanced exergy analyses of PCC with solvents for emission reduction. It focuses on (1) steady-state simulation of the closed-loop PCC system, (2) conventional and advanced exergy analyses of the CO₂ capture process, and (3) strategies to reduce exergy destruction and losses in the capture process. A detailed exergy destruction analysis is performed in this study, both for the absorber and the desorber columns of the system. These analyses allow for a better understanding of the exergy destruction due to a component’s own inefficiency and/or the remaining components’ inefficiencies. The analyses show improvement in reducing exergetic losses in the system without incurring additional penalties. The results show that the energy/exergy destruction in the monoethanol-based (MEA-based) CO₂ capture system (and hence the energy penalty) and the efficiency can be improved by recovering the avoidable exergy destructions in the system.

The present paper analyzes the exergy and the entropy generation for a stationary laminar flow in a two-dimensional horizontal rectangular channel with a porous matrix. Uniform heat flux is applied at bounding walls.The equations were treated by the code “FLUENT 6.3.26” which uses a finite volume discretization.After the validation of the numerical method used through the experimental work of Irfan Kurtbaç et al., we examined the influence of the Reynolds number on the entropy generation, exergy, and irreversibility.Numerical simulations are undertaken using a range of Reynolds number (600 ˂ Re ˂ 2200) and Darcy number (Da = 10−1).The main result worth noting is that increasing the Reynolds number increases the generation of entropy, irreversibility, and exergy.

An exergy analysis is carried out on a laboratory scale fast pyrolysis process. Mass balance and key compositional data are obtained from a lab scale plant operating at a biomass feed rate of approximately 1 kg/h. Exergy flows and losses are determined for the overall system, as well as the main subsystems, and the sensitivity of the exergy efficiency to reactor temperature and biomass feed moisture content is investigated. The optimal operating temperature for the reactor is within the approximate range 426–457 °C, providing a rational exergy efficiency of approximately 30%. The main exergy losses are found to be associated with the combination of the fluidised bed reactor and the char separation cyclone. The water-chilled condensers used to quench pyrolysis gases and to separate bio-oil are found to be the second largest source of exergy loss, primarily through irreversible exergy destruction and via noncondensable gas products. It is also estimated that increasing the moisture content of the feedstock will decrease the exergy efficiency of the overall system by about 2% for every weight percentage increase in feedstock moisture content.

Exergy and greenhouse gas emission analyses are performed on a novel trigeneration system driven by a solid oxide fuel cell (SOFC). The trigeneration system also consists of a generator-absorber heat exchanger (GAX) absorption refrigeration system and a heat exchanger to produce electrical energy, cooling and heating, respectively. Four operating cases are considered: electrical power generation, electrical power and cooling cogeneration, electrical power and heating cogeneration, and trigeneration. Attention is paid to numerous system and environmental performance parameters, namely, exergy efficiency, exergy destruction rate, and greenhouse gas emissions. A maximum enhancement of 46% is achieved in the exergy efficiency when the SOFC is used as the primary mover for the trigeneration system compared to the case when the SOFC is used as a stand-alone unit. The main sources of irreversibility are observed to be the air heat exchanger, the SOFC, and the afterburner. The unit CO₂ emission (in kg/MWh) is considerably higher for the case in which only electrical power is generated. This parameter is reduced by half when the system is operated in a trigeneration mode.

The main purpose of this paper is to introduce and investigate thermodynamic performance of a new combined power and cooling cogeneration cycle. In this cycle a hydrogen-fed solid oxide fuel cell (SOFC) and a gas turbine are used for power generation, and a generator-absorber heat exchange (GAX) absorption refrigeration system is used to produce cooling. Electrochemical equations for fuel cell and thermodynamic relations for components are solved simultaneously using the Engineering Equation Solver (EES). The simulation results are validated using the previously published data in literature. The comparison shows a good agreement between them with an error of less than 4%. The effects on the system performance are investigated of such decision parameters like current density and pressure ratio. The results show that for the same condition, the energy and exergy efficiencies of the proposed cycle are 52.29% and 4.61% higher than those of the stand-alone fuel cell, respectively. Fuel cell stack, afterburner, and generator/absorber assembly contribute the most in the overall exergy destruction in the cycle.

The increase in world population has become a problem in waste management and fuel consumption. Hence, the development of biofuel from waste has gained great attention in recent years to make environment clean. In this present work, the biofuel is derived from waste fish fat by thermal conversion process. The physical and chemical properties of biofuel are very close to diesel fuel. The experiments have been carried out to assess the combustion parameters of biofuel in a diesel engine. Also, analysis of performance and emission characteristics of biofuel were investigated. The combustion parameters like maximum cylinder pressure, rate of heat release, occurrence of maximum peak pressure and heat release rate, ignition delay, and total combustion duration were analyzed. Experimental results indicated a marginal increase in brake thermal efficiency at all loads compared to diesel fuel. The results show that despite of high NOx and CO₂, the engine has lesser UHC, CO, and PM than standard diesel fuel. The premixed and diffusion combustion duration is decreased with biofuel compared to diesel fuel. The engine was running smooth at all load conditions with biofuel. It is concluded that the biofuel derived from waste fish fat can be considered as a substitute for diesel fuel.

Comprehensive thermodynamic analyses, performance assessments, and comparative evaluations of active magnetic regenerative (AMR) and conventional vapor-compression-based refrigeration systems are presented in this study. The active magnetic regenerative (AMR) uses a magnetic material as a thermal storage medium and as a refrigerating medium. A parametric analysis is to investigate the influences of various operating conditions and/or parameters on the thermodynamic performance of the AMR cycle. In this regard, these performance results are compared with the published experimental data for a traditional refrigeration system with the same refrigeration capacity and temperature span. The results of this particular study show that the COP of the AMR cycle changes very little with varying hot source temperature. It is shown that the conventional vapor-compression-based refrigeration cycles offer better performance than the active magnetic regenerative refrigeration systems.

Today, it is important to explore the feasibility of substitution of diesel with an alternative fuel, which can be produced within the country on a massive scale for commercial utilization.Hence, efforts are being made all over the world, to find out an alternative fuel for the diesel engines. Deriving the fuel from waste solves the problem of fossil fuel scarcity and environmental degradation due to industrial wastes. In the present work, the biofuel is derived from industrial waste fish fat for diesel engines. It is produced through catalytic cracking, and its quality has been improved through distillation. A single cylinder 4.5 kW at 1500 rpm was used to find the suitability of biofuel and biofuel UD in diesel engine. The experimental results show that the brake thermal efficiency of biofuel and biofuel UD is almost same. The brake thermal efficiency for diesel, biofuel UD, and biofuel is 29.98%, 32.12%, and 32.4%, respectively. The CO, HC, PM, and NO_x emissions increase with biofuel UD compared to biofuel. There is a small reduction in CO₂ emission with biofuel UD compared to biofuel. Even though the cylinder pressure is high with biofuel UD, the intensity of premixed combustion is less. The ignition delay and combustion duration increased with biofuel UD.Finally, it is concluded that the fuel derived from industrial waste fish fat can be used as a fuel for diesel engine after distillation.

This study aims to develop a comprehensive decision support system (DSS) for design and management of local bioenergy supply chains by tackling inherent uncertainties. To this aim, a fuzzy programming-based multiobjective mixed integer linear programming (MILP) model is constructed. To explore the viability of the proposed DSS, computational experiments are performed on a real-world problem, and further analyses are conducted. The results reveal that the proposed model can effectively be used in practice.

Carbon capture for fossil fuel power generation draws an increasing attention because of significant challenges of global climate change. This paper aims to explore the optimal operation of MEA-based post-combustion carbon capture (PCC) process for natural gas combined cycle (NGCC) power plant. Levelized cost of electricity (LCOE) is formulated as the objective function to be minimized in optimization. The rate-based steady-state process model including the absorber, stripper and compression train and other auxiliary equipment was developed in Aspen Plus® to give accurate prediction of process performance. The techno-economic estimate was carried out for the base case for whole chain of NGCC integrated with PCC, CO₂ transport and storage (T&S). The optimal operations were investigated for the carbon capture level under different carbon price, fuel price and CO₂ T&S price. The study shows carbon price needs to be more than 100 EUR/ton CO₂ to justify the total cost of carbon capture from the NGCC power plant and needs to be around 150 EUR/ton CO₂ to drive carbon capture level to 90–95%. Higher NG price and CO₂ T&S price would cause a greater operating cost of running carbon capture process; thus a higher carbon price is needed to rejustify the cost of high carbon capture level of PCC process.

Post-combustion CO₂ capture (PCC) is considered the most feasible and viable process for CO₂ abatement in the power sector. Aqueous monoethanolamine (MEA) solvent, traditionally used in this process, brings along challenges, namely, huge energy requirement for solvent regeneration, huge solvent flow rate leading to large equipment sizes, and chemical and thermal degradability, among others. In this study, the prospects of replacing aqueous MEA solvent with a blend of ionic liquid (IL) and MEA are explored. IL is generally chemically and thermally stable among other encouraging properties but is however expensive. A blend of IL and MEA is predicted to have shared qualities of MEA and IL and therefore could hypothetically contribute to meaningful reduction in overall cost of the process.This hypothesis is investigated in this study by performing a technical and economic analysis of the process using aqueous blend of IL ([Bpy][BF₄]) and MEA as solvent. A rate-based model of the process developed in Aspen Plus was used to perform the technical and economic studies. Technical and economic analysis of PCC with aqueous blend of IL and MEA as solvent have not been covered in existing studies. Also, reported models are derived using equilibrium-based approach.From the analysis, it is found that with about 5 wt% IL concentration, total solvent cost approximates closely to typical solvent cost for the MEA only process; higher IL concentration leads to significant increase in solvent cost. Also, the simulation results showed that the rate-based [Bpy][BF₄]-MEA process can save about 7–9% regeneration heat duty and reduce the solvent flow rate by about 11.5–27% compared to the conventional MEA only process.

In this work, a comparative study and evaluation of CO₂ capture process using monoethanolamine (MEA) and diethanolamine (DEA) is reported. Ten different process configurations from a power plant are simulated and compared in terms of the total equivalent work and the reboiler duty. Process flowsheet modifications present a good performance with respect to the reduction of energy consumption. It is carried out with a 0.38–4.61% of reduction for MEA and 0.27–4.5% for DEA. Furthermore, a detailed analysis is presented to study the effect of four significant parameters in capture process, including various temperatures, pressures, and concentrations. This analysis presents the influence of the interaction between the solvent and the process, which is essential in post-combustion process design to develop an optimization strategy.

Nowadays, requirements posed by global warming and climate change especially have become imperative to reduce CO₂ emissions for all sectors. The maritime sector is a rapidly growing one, and the global emission effect of this sector has reached to the level of 3%. Besides, this sector has important legal obligations. In this respect, the maritime industry having intensive consumption of fossil fuels including mainly diesel fuel should develop energy-efficient solutions. For this purpose, in this study, first energy and exergy analyses of a diesel engine under different loads were made, and CO₂ emission loads of engine were examined separately. According to results, energy and exergy efficiencies of full load were found to be 41, 12%, and 30, 71%, respectively. At the end of the study, the improvement potential of the engine performance was evaluated together with the reduction of the emission potential. Additionally, some recommendations about use of exergy analysis in the maritime applications were made.

This paper reconsiders the Novikov and Curzon–Ahlborn power plant model in a completed form. The optimization of the proposed plant is done and comparison of various control volumes (converter; engine; engine with heat source and sink; or system: system in the environment) with respect to two objectives functions, power, and created entropy rates. Maximum power condition differs generally from minimum entropy generation rates. Moreover, a differentiation is enlightened concerning Angulo-Brown and Yan ecological criterions.