Advances in Fluid and Thermal Engineering

In recent era, the growing requirements of miniaturization and weight reduction leads to remarkable thermal loads on small and sensitive electronic devices. This in turn inevitably necessitates the thermal management of electronic devices to enhance the energy efficiency and reliability of the complete systems. Several techniques are implemented for cooling of electronic devices; however, these methods have the drawback of lower heat transfer rates. In contrast, thermal management via spontaneous drop motion is an efficient passive cooling method. Recent progresses in surface technologies and material science facilitates fabricating wettability gradient on the surfaces. These surfaces enable self-propelled motion of liquid droplets at surprisingly high velocities, which also enhances the self-cleaning properties. However, drop dynamics on wettability gradient surface is yet not well understood and is of substantial scientific interest worldwide. Drop motion on wettability gradient surface is a complex phenomenon which involves asymmetric spreading on surface, directional retraction followed by detachment from a less wettable region and migration towards a more wettable region. In this background, the present work aims in the fabrication of wettability gradient surface for drop-based thermal management of electronic device using plasma-based coating method. In addition, experiments are performed on the graded surfaces to investigate the drop velocity on the wettability-graded surfaces.

When a porous media is introduced into a flow path, it significantly alters the flow path's hydrodynamic and thermal characteristics. Due to the complex structure of the solid matrix in the flow route, the fluid particles encounter a significant amount of resistance in the form of viscous and inertial momentum loss, resulting in a proportionally considerable pressure drop along the channel. This results in a higher input power required to pump the fluid through the channel, although flow through porous media has been demonstrated to improve heat transfer performance. In electronic cooling applications, the lack of available space lowers the size of channels, making pumping more difficult. While partially porous channels have been found to meet this requirement, their pressure drop is many orders of magnitude more than that of non-porous channels under similar conditions (Hadim in Forced convection in a porous channel with localized heat sources, 1994; Hadim and Bethancourt in Numerical study of forced convection in a partially porous channel with discrete heat sources, 1995; Ahmed et al. in Int Commun Heat Mass Transf 108:104336, 2019; Perng et al. in Int J Therm Sci 50(10):2006–2015, 2011; Zimbeck et al., Loop heat pipe technology for cooling computer servers, pp 19–25, 2008). As a result, it is critical to seek out strategies for optimizing the pressure drop in these channels while maintaining their thermal performance. This parametric analysis considers a partially porous channel with alternate combinations of porous and non-porous zones separated uniformly along the flow direction. The 2D planer and 3D channel are investigated numerically for laminar, steady, incompressible, forced flow subjected to asymmetrical bottom wall heating utilizing discrete heat sources. Additionally, these heat sources are positioned beneath the porous zones. Forchheimer-tenure Brinkman's was extended The Darcy equations are solved for momentum conservation, taking into consideration viscous and inertial losses, as well as the boundary impact. Due to the assumption of local thermal equilibrium between the solid matrix and saturated fluid, an energy conservation single equation model is solved (Carbonell and Whitaker in Fundamentals of transport phenomena in porous media. Springer, pp 121–198, 1984; Straughan in Convection in porous media 165, 2008). The overall pressure drop and heat transfer coefficient are investigated parametrically in two distinctive conditions in a mini-scale channel. In the first scenario, a two-dimensional numerical analysis was conducted to investigate the effect of substituting oblique porous plugs for normal porous plugs with the intent of enhancing the thermomechanical performance of the plug. The obliqueness of the porous plug was changed in both forward and reverse directions for this study. It was observed that forward oblique porous plugs degraded overall performance by reducing heat transfer and increasing the pressure drop in the channel, whereas backward oblique porous plugs augmented the overall performance of the channel by significantly reducing the pressure drop at higher angles of obliquity without impacting the heat transfer coefficient. In the second scenario, a three-dimensional analysis was conducted to determine the effect of introducing solid and porous ribs on the pressure distribution and heat transfer coefficient of flow through a mini-channel subjected to a constant heat flux boundary condition at the bottom wall. The solid block and porous blocks with varying permeabilities were compared to the channel without any blocks under identical flow and heating conditions. It was discovered that solid and porous blocks functioned almost identically at lower permeability values, with the overall effect of increasing the pressure drop in the channel while maintaining the heat transfer coefficient. However, using porous blocks with a higher permeability resulted in a massive improvement in heat transfer performance without affecting the pressure drop.

The reciprocating compressor plays a significant role in industries like chemical industries, fertilizer plants, oil and gas refineries etc. where the availability of this machine is very much required to ensure the working of the plant without any failure and safety operation. The timely prediction of failure of the compressor or detection of performance degradation can avoid many failure consequences like reduction in down time, improved safety, reduction in maintenance cost and improved efficiency of plant. Thus to have a safe operation and effective control on maintenance activities the condition monitoring is better tool to diagnose the health of machine. In the present work these faults are investigated at different levels of safety, cost and effectiveness of the compressor.

Superior performance, quick response to variable load, and compactness make supercritical CO2 (sCO2) power cycles suitable for waste heat recovery (WHR) applications. This paper proposes a novel sCO2 WHR cycle for high-temperature (>300 °C) applications. The proposed cycle incorporates two recovery heat exchangers, two recuperators, two turbines, and a single compressor. A comprehensive thermodynamic analysis of the novel sCO2 WHR cycle is presented for utilizing the waste heat of gas turbine exhaust. The influence of cycle parameters on cycle performance in the context of a WHR cycle is discussed. The low side, high side pressures, and the mass flow split ratio between the high-temperature and low-temperature turbines are optimized for maximum power rather than thermodynamic cycle efficiency. The performance of the proposed cycle is compared with other sCO2 cycles operating under similar conditions. The analysis shows that the proposed cycle produces high performance while significantly reducing heat exchanger sizes. Additionally, the cycle exhibits significantly stable performance under off-design conditions and offers a more comprehensive operating range than the standard sCO2 WHR cycles cited in the literature.

The present research is focused on analyzing the pressure fluctuations associated with two-phase flow. Different flow structures in the pipe are generated by varying the flow rates of air and water phases. For different regimes of two-phase flow, pressure signals are measured with pressure transmitter. A methodology based on cross-recurrence analysis of pressure signals recorded from two different locations in the pipe is proposed in this study to identify the stability of the two-phase flow pattern. Distribution of recurrent points in the cross-recurrence plot reveals identical characteristics of two dynamic signals. Similitude between the signals obtained from two pressure transmitters is observed to be low when two-phase flow passes through the transmitter. Such low similitude implies the instability of two-phase flow patterns. Cross-Recurrence plot of stratified flow, wavy stratified flow and intermittent flow regimes are analyzed. Presence of slug is indicated by a rectangular black patch in cross-recurrence plot. Less attunement between stratified and slug flow is revealed by white spaces without a single black dot in the cross-recurrence plot. Such unadulterated white band implies the existence of dissimilar characteristics between two signals.

A two-phase closed thermosyphon is a passive two-phase heat transfer device. Its thermo-hydrodynamic performance depends on the operating conditions, working fluid, filling ratio, inclination angle, and geometry. This work focuses on geometry and analyzes the effect of diameter variation of a thermosyphon with filling ratio unity, the average pipe diameter of 22 mm, pipe length of 500 mm, and water as the working fluid. Thermo-hydrodynamic simulations are carried out for an equivalent constant diameter thermosyphon, and linearly varying diameter thermosyphon whose average diameter is equal to the equivalent constant diameter thermosyphon. It is found that the linearly varying diameter thermosyphon is more effective than the equivalent constant diameter thermosyphon because the linearly varying diameter adds a favorable pressure difference along with buoyance force. Hence, the thermal and hydrodynamic resistance of the linearly varying diameter thermosyphon is lower as compared to the equivalent constant diameter thermosyphon.

The worldwide utilization of fuels is evidently unsteady, causing a worldwide financial instability; consequently, all countries, have been encouraged to track down different choices to supplant the utilization of oil. Hence, the issue could be tended to by utilizing biodiesel as another option; consequently, an experimental examination was directed on an automotive compression ignition engine broadly utilized in India's transportation area, fuelled with different mixes of bio-diesel synthesized from discarded edible oil (Soybean). Engine execution is likewise assessed utilizing the diesel fuel in a current automotive compression ignition engine without any hardware changes in the engine. A single stage process of biodiesel synthesis known as transesterification was performed for the synthesis of the biodiesel from disposed edible oil. The methanol to oil proportion was kept steady all through the experimentation (6:1). The basic properties of the disposed edible oil biodiesel were also examined in accordance with protocols associated with biodiesel. Engine tests were performed utilizing different biodiesel and diesel mixes like B15, B25, B35 and B45 in order to investigate the engine execution and exhaust characteristics such as fuel utilization, specific fuel utilization (SFC), break thermal efficiency, and smoke density etc. The performance and exhaust characteristics of the engine on B15 blend was found comparable to the conventional diesel fuel.

The electronic components, instruments, sensors, and other satellite payload subsystems generate a significant amount of heat during repeated transient duty cycles. The thermal management of such subsystems of the satellite payload becomes more challenging under the influence of the microgravity environment. The rapid temperature fluctuations caused due to stringent space environment may lead to the overheating/failure of the electronic devices. The phase change materials (PCM) are the natural fit for the thermal control of such satellite subsystems where the heat dissipation is non-continuous. A three-dimensional PCM-based thermal control unit (TCU) having extended fins as heat transfer enhancers is designed to control the undesirable temperature fluctuations and maintain the temperature of the satellite subsystems in the operating range. However, the absence of convection and characteristics of the microgravity environment may adversely affect the melting of PCM in the TCU. Additionally, the rigorous structural requirements and spatial demand of the satellite subsystems offer additional challenges to spacecraft thermal control management. The present work investigates the effect of inverting the heat source direction on the melting process of PCM under the influence of a microgravity environment. The energy storage process of the selected PCM is numerically examined at different gravitational acceleration values, changing the heat source's direction. A three-dimensional CFD model is developed using the enthalpy porosity technique to simulate the heat transfer and flow characteristics of PCM-based TCU. The governing equations are non-dimensionalized, and the results are presented in terms of dimensionless numbers.

Rapid cooling can be obtained by a very innovative technique of depressurizing liquid in a controlled volume. This feature of attaining the possible minimum temperature within a few minutes led this technology to be used for several essential applications such as waste-heat recovery, desalination, drying of nuclear waste, and thermal management of aerospace equipment. The present study intends to develop a flashing experimental system to obtain insights into the mechanisms and the influential parameters to establish a controllable flash technology. The operating parameters such as the initial temperature of water present in a flash chamber and depressurized liquid through a connected vacuum tank are shown to play a vital role in controlling the flashing conditions. A rigorous number of experiments were performed ranging from 45° C to 85° C with varying pressurizing effects to obtain the optimum flashing conditions as per the applications. The drop in the water temperature due to the sudden pressure drop created inside the flash chamber connected with a large vacuum tank is measured by connected K-type thermocouples. A comparison of flash evaporation with normal evaporation/cooling is also presented, which confirmed the high efficiency of 90% of cooling obtained through flash evaporation.

The study intends to provide the optimal configuration for the position of Heat Transfer Fluid (HTF) tube under fin assisted thermal energy storage system for the applications of cooling. The aim of the numerical study is to find the effect of different positions for HTF flow on enhancing the phase change process. The HTF can either be passed through the inside of the Phase Change Material (PCM) which is an interior process or through outside of it that is the exterior process. The change has been done such that HTF volume is kept constant. A most economical fluid i.e., water is used as PCM while the refrigeration system is used to convert water into ice. The used PCM for the cooling applications is water as it is having a high latent heat of fusion and the solidification point of water lies in a lower temperature range. A V-shaped fin is incorporated with the respective direction of cooling like external V shaped fins that are employed for exterior cooling and similarly internal fins for interior cooling. The variations in heat transfer parameters such as heat transfer rate and heat transfer coefficient are studied at these different positions of HTF. Due to the increment in the area of contact of PCM with HTF that takes place in the case of exterior cooling, the heat transfer properties are enhanced compared to the interior cooling. Also adding fins provides a larger surface area for the heat transfer to take place and improves the solidification.

Linseed crop may be produced conveniently in India due to weather and conditions of soils in the country. In this paper, linseed plant and its oil, production of linseed biodiesel, its physiochemical properties, comparative analysis of biodiesel properties, its benefits and limiting factors, comparative study of diesel with biodiesel, energy audit and biofuel certification and findings and its results of authors, relating to this topic have been discussed. Standard energy audit and biofuel performance certification are found as challenges in future. After the transesterification procedure, the viscosity of Linseed oil biodiesel decreased to a large extent. Free fatty acid reduced from 3.5 to 0.75 and the viscosity reduced from 2169 to 362 mm2/s after esterification. There is a reduction in the emission of carbon monoxide, unburned hydrocarbon and smoke emissions as compared to diesel. Metal based, oxygenated, cetane number increasing additives and antioxidant additives are used to mix with the biodiesel to improve fuel quality. The objective of this paper is that linseed biodiesel could be produced and used conveniently in India.

Boilers and pressure vessels with riveted joints are used to contain pressurized fluids and are subjected to complex loads under static and dynamic situations. Pressure vessel failure happens both circumferentially and longitudinally. Circumferential riveted joints are critical to the design of pressure vessels because the circumferential stress is double the longitudinal stress. Boiler shell with circumferential riveted joints is studied at pressures between 2.5 and 5 MPa for structural analysis. The riveted joint was created using SolidWorks software and analysis performed on Ansys software. The proposed joint is investigated to examine how structural steel, titanium alloy, and nickel-cobalt-chromium alloy affect the vessel's performance. The results are presented, and a comparison is made to determine which material is more suitable. Static results demonstrate that Boiler shell joints of nickel-cobalt-chromium alloy have a smaller total deformation (0.067 mm) and lower Von-misses stress (63.37 MPa) than structural steel and titanium alloy at an internal pressure (2.5 MPa). The Maximum shear stress of titanium alloy (30.63 MPa) shows better result as compared to Structural steel (33.52 MPa) and Nickel-cobalt-Chromium alloy (34.11 MPa). Data for fatigue life, damage, safety factor and sensitivity for candidate materials are taken from Ansys software. The findings demonstrate that the boiler shell with circumferential riveted joint of Titanium alloy has a good fatigue life, low fatigue damage, and a high safety factor at high internal pressure when compared to the circumferential riveted joint of structural steel, Nickel-cobalt-chromium alloy. The final result shows that the selected materials will survive and function well, while titanium alloy and nickel-cobalt-chromium alloy surpass structural steel.

Imaging techniques have gathered attention in the recent past owing to it non-intrusive nature and superior results in quantifying the dynamics of fluid flows. The current study is an attempt to use imaging techniques in determining the velocity values across different regimes of a hydraulic jump. Two techniques, Feature Correlation Velocimetry (FCV, which depends on the advection on naturally formed corrugations on liquid surfaces) and Particle Tracking Velocimetry (PTV, which depends the on tracking of externally seeded tracer particles across successive images), have been employed in this study to quantify the dynamics of fluid flow over a hydraulic jump across its different spatial regions. Results show that both FCV and PTV are successful in quantifying the flow nature in all regimes (involving both laminar and turbulent nature of flow) of a hydraulic jump. In addition, FCV proves to me more efficient in providing the temporal fluctuations of a flow compared to PTV owing to the use of cross correlation algorithms used for the same.

Gas compressors are used to compress gas from an initial intake to higher exhaust pressure through a reduction in volume. Higher-pressure reciprocating compressors are used to dispatch the gas for long distance. Reciprocating gas compressors are important to oil and gas industry. Major objective of this study is to explore about failure analysis of reciprocating gas compressors so that failures can be reduced and performance can be improved. Here changes in maintenance practices are followed to run the compressors smoothly. Despite of best practices failures are observed due to different reasons. The early detection of defects is necessary so Failure mode and effect analysis (FMEA) method is adapted to analysis failures. Data is collected from the Oil and Natural Gas Industry and suggestions/experience of experts is also considered. Risk priority number (RPN) is calculated. Several steps are applied to reduce risk priority number (RPN). After that it is observed that failures are reduced and performance is improved. Major findings are that valves are the weakest part of compressor, being the most frequent failure and consume big share of maintenance cost. The highest RPN score is 135 for valves and after implementation of recommendations revised RPN score comes to 30 that is approximately 78% less. To reduce RPN for valves, several steps are recommended i.e. use poppet type valves to handle liquid better in place of plate type valves, use of non-metallic valves, predictive periodic maintenance to be followed. This will increase the availability of compressor and reduce maintenance cost.

“Heat transfer and friction factor” properties of a double pipe heat exchanger furnished with equally gap perverted tape component was investigated tentatively. The diameters of outside and inside tube are 25.8 and 50.6 mm, sequentially, hot and cold water was employed as operating fluids on the tube and shell sides, sequentially. For the construction of perverted tape we are using the stainless steel of length 1500 mm and thickness 1 mm. These perverted tapes were arranged in investigational tube segment in two ways: (i) complete-length typical perverted tape at dissimilar perverted proportions (y = 6 and y = 8) and (ii) perverted tape with varied free space ratios (L = 1, 2 and 3). The findings acquired with the tube with the perverted tape inserts are differentiated to that obtained from the tube with no perverted tape. The outcomes show that as the twist ratio grew, so did the heat transmission coefficient. In contrast, increasing the free space ratio (L) improves both the friction factor and the coefficient of heat transfer. For friction factor and Nusselt number, the findings from every example were connected. The projected friction factor and Nusselt number from the correlations were then shown against the investigational detail. It is discovered that the Nusselt number was within 15percent and the friction factor was within 10%.

A combined hydrokinetic rotor can outperform the Darrieus and Savonius rotors on their own. The outside diameter of the Darrieus rotor is changed in the present study to alter the combined rotor configurations. In this work, the Darrieus rotor diameter is determined to be between 0.15 and 0.30 m. The study's aims are met through the use of a numerical technique. According to the numerical calculations, the diameter of the Darrieus rotor has a potential to alter the combined rotor's performance. The Darrieus rotor diameter of 0.20 m is found to be the best. The highest power coefficient yields as 0.199. The flow interference is more pronounced when the distance between the two rotors is small, according to flow visualisation. With a bigger Darrieus rotor diameter, the combined rotor's peak torque is found to be higher. The torque pulsation level is highly influenced by the diameter of the rotor (solidity of the rotor).

A steam turbine is one of the most widely used equipment to generate electricity. In this data-driven world, the development of predictive models for such equipment has become necessary. In this paper, machine learning models are developed to predict the output generated by the steam turbine. Five predictive models are developed and compared. It is found that a third-degree polynomial regression model with an R-squared value of 87% and Mean square error value of 94.9 is found to be the best-suited model as per the requirement.

In this numerical study the bubble formation at different nozzle height of 2 mm, 4 mm and 5 mm with constant radius of 1 mm and constant air flow rate at 100 ml/min is performed. The Volume of Fluid (VOF) method coupled with Level-Set(LS) method is used in the simulation of bubble formation. The axisymmetric condition is taken in this study with no slip boundary condition and constant wettability condition of 45° at the solid surfaces. The properties of air and water are taken at constant temperature 20 °C. We first validate our data with the simulation result of Gerlach et al. (2006). We then calculates the bubble volume after detachment at different nozzle height. We also calculate the pinch-off time at different nozzle length which is also very important factor in bubble formation study.

Over the last few decades, the utilization and need of liquid helium in the vast field of cryogenics is increasingly used in various sectors. Thereafter, many research projects have been carried out with an aim to obtain a more comprehensive understanding of the storage and transportation systems for liquid helium. A main component which needs to be taken into account for a cryogenic system is the method in which the fluid is to be stored with minimum losses and transported safely. Heat leak is a major concern in the design of storage and transport systems for cryogenic liquids and hence selecting the proper thermal insulation to be used on such systems becomes very important. Material compatibility is another parameter for the design of storage systems. The material must be feasible with such low cryogenic temperature. This paper will discuss each parameter essential for the mechanical design and safety for the liquid helium storage vessel. The scope of this paper is to provide a comprehensive review & discussion of research in the areas of materials, mechanical design, and structural integrity. Moreover, a design procedure for a liquid helium dewar is discussed. The various mechanical design procedure and aspects of the vessel are done using ASME Boiler and pressure vessel codes. Within this paper, the knowledge gaps are identified and corresponding research work of design of cryogenic vessels is done.

The current study investigates the feasibility of substituting dimethyl ether for diesel in a stationary single-cylinder CI engine. A significant part of the world’s energy requirements is met by fossil fuels, which are depleting at an alarming rate. Poisonous pollutant emissions, as well as global warming, necessitate the search for a suitable, cost-effective, and sustainable renewable alternative source of energy. Di-methyl Ether seems to be a promising renewable source of energy that is less polluting and eco-friendly. It is also a potential hydrogen carrier for the future possible hydrogen economy.In present Investigation the performance and emission characteristics of the four stroke single cylinder water cooled VCR Engine at fixed compression ratio is studied in dual fuel operation using DME and diesel. DME is inducted into the intake manifold of the engine to get mixed up with air using timed manifold injection with injection durations of 3, 4, and 5 ms. Brake thermal Efficiency (BTE), Brake specific Energy consumption (BSEC), Incylinder pressure, and emissions were analyzed. Dual fuel operations were performed at standard Diesel operation parameters generated a need to optimize the controlling parameters of ignition.

The performance of TCC for nominally flat metallic contacts has been predicted using an artificial neural network (ANN) model. Experimental inputs and outputs from a previous work of one of the authors, Tariq and Asif (2019) are employed in the ANN model to predict the results. Therefore, inputs to the model include effective thermal conductivity, Vickers hardness, reduced modulus of elasticity, RMS roughness, Average asperity slope, and contact pressure, while Solid spot conductance, drop in temperature across the border, and percentage thermal loss are the model's outputs. Experiments on the performance of thermal contact conductance are carried out, with the test results serving as target data for training the ANN model. ANN results forecasts are shown to be in good agreement with the experimental test results.

Stenosis is the narrowing of artery wall due to the accumulation of fats, proteins etc. The thickening of arterial walls is a common occurrence as people get older. To study the effect of stenosis in the flow through the artery is important. In this study, variation of near wall hemodynamic parameters like wall shear stress (WSS), Time Average Wall Shear Stress (TAWSS) and Oscillatory Shear Index (OSI) were studied for five different stenotic severities at peak of the systole (maximum velocity) on brachial artery bifurcation. The WSS on the arterial wall was determined, and it was discovered that the most wall shear occurs around the stenosis neck. It was also found that as the severity increases, the flow rate through the artery decreases and by around 60% severity there is more region with high OSI resulting in more recirculation area which favours the growth of the stenotic plague.

Day by day the shape and geometry of the electronic devices are minimized and their cooling becoming a very difficult task. To increase the life and efficiency of the device of the devices, it is required to maintain the device temperate below the working temperature of the device and remove the heat from the device. The present works demonstrate the numerical analysis of the mini channel using three different polygon geometries such as rectangular, trapezoidal and hexagonal cross sections. The water is used a coolant in the channel. Numerical simulation have been performed using dimension less Reynolds number ranging from 200 to 1000 with constant heat flux boundary condition on the wall base surface of the mini channel in ANSYS fluent. Further, various simulations have been performed to analyze the effect of geometry and inlet velocity of the heat transfer coefficient (HTC) and pressure drop in the mini channel.

The economic development over the past few years has resulted in an exponential rise in the energy consumption. The use of Thermal Storage systems has widely been researched over the years and it significantly helps in fulfilling the need for efficient energy use in different work areas. Heat storage helps in increasing the overall performance efficiency of the plant and therefore reduces the cost of power generation. In order to increase the efficiency of the current Thermal Cascade Storage System variations in the parameters like Heat Transfer fluids, Phase Change Materials and input temperatures are being studied. In this study, the design parameters, charging and discharging time of the system, outlet temperature and the thermal storage capacity for Heat Transfer Fluid (HTF) Therminol oil (VP-1) and water with the selected phase change materials accordingly that are observed by simulation on an ANSYS software and the results are compared between the two systems. For Therminol Oil as HTF the charging time comes out to be 5 h 41 min 21 s (20,481 s) and during the discharging process the inlet temperature of HTF is 25 °C which gets heated up to 105–125 °C for which the total rise in temperature of HTF is around 80–100 °C. Whereas in the case of water being used as HTF the total charging time is 5 h 37 min 47 s (20,267 s) and the inlet HTF at 25 °C comes out at 39–44 °C therefore, the rise in temperature comes out to be 14–19 °C after discharging. According to the observation, the charging time for both the HTFs is more or less the same. It is therefore seen that using Therminol oil as HTF is beneficial and economic in a TES system.

The Experiment examines the combustion properties of pure diesel blended with n-hexane and n-pentane. This study showed several combinations of temperatures and pressures of air inside the engine cylinder. The study was conducted at different blends of 10 to 40% (with an interval of 10%) of n-pentane and n-hexane. Ignition delay was recorded at different air pressures with increasing temperatures. Results show that on increasing the temperature and pressure the ignition delay decreased. Two properties of Ignition delay are very important i.e., temperature and pressure. Ignition delay is lower for the blends of n-pentane than that of n-hexane and diesel comparatively. The blends of n-pentane decrease the ignition delay of the engine effectively at low temperatures.

Heat and mass transfer equipment is the heart of many industrial applications in the thermal engineering. Apart from the driving potential difference, the system's overall process efficiency is steered by how these fluids interact. The interaction pattern depends on the type of heat exchanger used and employed based type of fluid, phase flow, density, chemical composition, viscosity and many other thermodynamic properties of interacting fluids. Augmentation in the heat transfer is one of the promising and challenging tasks in the thermal dealings. The increase in energy requirement and consumption has made this issue more crucial. Many researchers reported that methods of increasing heat transfer can be broadly classified into three major divisions as active techniques, passive techniques, and a combination of these two techniques i.e. compound technique. Active techniques involve the influence of fields such as electric, magnetic and acoustic. Whereas, in passive methods, additives are added to the working fluid or new surface textures are formed on the heat transfer surfaces. Nyborg, J Acoust Soc Am 25:68–75, 1953, [1] reported that under the influences of sound sources the fluid particles moves sinusoidal as well as forms patterns like steady vortices or time independently circulations in the fluid body. As high intensity sound projected into the fluid, it generates the effect of some kind of streaming in the fluid called as quartz wind. Sonication is the act of applying sound energy to agitate particles in a fluid.

Today’s modern world with a huge need for transportation heavily depends on diesel vehicles and is thus dependent on quickly depleting fossil fuels. This high demand for diesel fuel will eventually lead us to a scarcity soon and to deal with this, society needs an alternative fuel that can be used in the existing engine without any compromises. Biodiesel is a fuel made by transesterification of non-edible oils with diesel. This is a comparative study focusing on engine performance when fueled with biodiesel based on Castor and Karanja oil. A total of 8 sets of biodiesel blends were prepared with percentages varying from 10–40% of Castor and Karanja biodiesel. In this study, four performance parameters indicated power, BSFC, mechanical efficiency, and BTE were investigated. The study revealed mixed results from these blended biodiesels. Karanja biodiesel shows a higher indicated power value outperforming the Castor oil biodiesel as well as the pure diesel. Karanja biodiesel, on the other hand, performs better in brake thermal efficiency unlike Castor biodiesel with lower brake thermal efficiency overall. In terms of mechanical efficiency, Castor biodiesel has the better results with Karanja biodiesel being the lower. Finally, the BSFC is quite equal for most of the blends aside from a no-load condition.

Due to the destructive nature and limited supply of non-renewable sources, there has been a significant shift from non-renewable to renewable energy sources in the last two decades. Various research studies are taking place to enhance the efficiency of devices that work on renewable energy sources. Solar energy is the most famous field of research in renewable sources as it is the source that is present all around the globe. Various devices and technology were created from time to time to use solar energy effectively. This research review mainly focuses on three famous solar energy technologies: solar fabric, solar thermal fuel, and solar glass panes. The construction and working methodology of such technology has been discussed in this review. Further other points like solar energy conversion efficiency and specific limitations are also discussed here. The future growth and another challenge to the discussed technology are also considered.

Solar energy became the most popular alternative source of energy because of its ease of availability. Solar concentrators convert beam radiation to thermal energy, there are two parts of a concentrator Mechanical and Electronics part. Mechanical part consists of the Reflector and Receiver, its shape, its support and its base. Electronics part consists of tracking, sometimes receiver is also a part of electronics. Concentrators can be of various types such as parabolic trough, parabolic dish etc. Parabolic Dish has huge potential to extract ample amounts of energy from solar and the main advantage of parabolic dish is that the solar energy can be either transformed to another form using Sterling Engine or it can be directly used for desalination process. The objective of the paper is to discuss different parameters of Parabolic Dish such as important angles required for tracking with its implementation in the tracking system, required formulas of various parameters of a solar parabolic dish such as Solar Azimuth angle, Zenith Angle, the Focal point of Dish. This paper also reviews different features of facets used in parabolic dish reflectors and its effect on parabolic dish. Some diverse applications are discussed such as Micro Gas turbine application with the help of PDC system which showed an electrical efficiency of about 18.3% and PDC can be used as a boiler in a small-scale steam power plant.

Effective use of refrigerant is a vast part of our day-to-day life in the field of Heating, ventilation and air conditioning systems. A wide range of refrigerants plays a vital role in the heat exchange process in this particular field. Since the first invented Air Conditioner in 1902, refrigerants have been modified consistently. Various nano-particles are dispersed into the base refrigerants to form nano refrigerants. Various data researchers had suggested from their experimental analysis to enhance nano-particle-based refrigerants. Nano Lubricants have extraordinary capabilities to enhance their refrigerative properties. This paper has reviewed research on conventional refrigerants and their harmful impacts and discussed the necessity to move towards advanced technology. We have done an extensive analysis of the development of refrigerants in the field of efficiency, environmental effects, heat transfer enhancements and pressure drop capacities. We have briefly discussed the effects of dispersion of nano-particles like Al2O3, CuO, TiO2 etc. into the base refrigerants in the paper. We can quickly identify a better refrigerant for the near future from the study.

This paper represents a numerical approach for a heat exchanger with triple tubular concentric heat exchanger (TTCHE). The performance for the TTCHE of counter flow type are numerically validated. Variation of Temperature for the flow of three different fluids cold-hot-normal (CHN) & normal-hot-cold (NHC) throughout the length of the triple tube are calculated by using CFD commercial software ANSYS 19.2. Water is applied; hot fluid flows in the middle tube at all times, while the flow of cold and normal fluid in the inner and outer tubes, which can be alternated. The tube length is 4 m; the outer diameter of outer pipe, intermediate pipe and inner pipe are 0.1015 m, 0.076 m & 0.05 m subsequently. Each tube has a thickness of 1.50 mm. After that, we have theoretically calculated the overall coefficient of heat transfer by using Al2O3 & TiO2 nanofluids in 0.01, 0.03, 0.05 & 0.07 %wt. fraction instead of normal fluid in both cases (CHN & NHC) and we found that increasing the wt. fraction in nanofluids the heat transfer rate increases. The results obtained shows better result in NHC arrangements.

The current research used water base aluminium oxide (Al2O3) nanofluid as a coolant in a photovoltaic thermal system, and established a 3-dimensional CFD model to investigate the thermal performance of a Photovoltaic system with and without cooling. Ansys software 18.2 is used to investigate heat transfer and fluid flow in the photovoltaic system. Further Ansys fluent software is used to model the heat transfer between the panel layers with the absorber plate and the nanofluid, whereas the Ansys steady-state heat transfer software is used to simulate solely the heat transmission between solar-PV panel layers and natural convection. Sun hours (solar radiation) heat transfer is not modelled, on the PV panel layers a variable heat flux is investigated. DesignModeler software of Ansys is used to create the geometry simulation for the CFD analysis tool and Ansys Meshing software is used to mesh it. Finally, the heat transfer results were obtained with and without cooling at different heat fluxes 850 w/m2, 950 w/m2, 1050 w/m2 with a constant flow rate of nanofluid 30 kg/h having volume 0.5% concentration of nano-particles and PV/T system maintain temperature with varying heat flux at a lower level.

Effusion cooling represents the state-of-the-art cooling methodology for liners in modern gas turbine engine combustors. Advanced combustion techniques in aero engines require highly effective effusion cooling schemes for the combustor liner to protect it from extremely hot gases by consuming a minimum amount of air for cooling. The primary intention behind the present study is to find the best cooling performance for a particular phase of flight. The phase of flight considered are idle (DR = 1.2), takeoff (DR = 5) and cruise (DR =  5). The combustor liner is modeled as a flat plate with 72 coolant holes with the hole diameter d = 2 mm, with three different inclination angles α =20°, 30°, 40° and along the streamwise direction the pitch to diameter ratio of 4 is chosen. The mainstream conditions are maintained with the inlet velocity of 24 m/s, the temperatures as 361 k, 750 k and 1500 k. The coolant to mainstream blowing ratios are maintained at 1, 2 and 3, and the coolant temperature is 300 k. Area averaged cooling effectiveness is obtained by using CFD simulation using ANSYS® Fluent solver and the flow field is solved by using k-ϵ with an enhanced wall treatment turbulence model. The numerical results are validated with the experimental values available in the literature. The area averaged results showed that for a phase of flight the cooling effectiveness increases with an increased blowing ratio. The coolant film thickness increases as the blowing ratio is increased. The shallow coolant injection angle provided better cooling effectiveness.

Utilization of waste heat has become an essential consideration in energy savings. Methods that are used for waste heat recovery (WHR) are primarily meant for the performance enhancement of thermal systems with increased efficiency and fuel saving. In this present study, a waste heat recovery system (WHRS) has been incorporated to evaluate the performance of Indian vehicles operating under BS IV and BS VI vehicular emission standards using diesel and gasoline fuels. The study compares the performance of the systems without having a WHRS. When the waste heat recovery system is used, the engine exhaust has been suitably utilized for preheating the inlet air to the engine and for cabin space heating using a compact heat exchanger. The use of preheated inlet air is found to cause a reduction in fuel consumption. Also, by employing the waste heat recovery system the energy and exergy efficiencies of both BS IV and BS VI engines are found to be improved irrespective of the fuel type. The BS IV and bs vi gasoline engines are found to be more efficient in terms of energy and fuel savings whereas, the BS VI diesel engine is the least efficient.

In the current scenario, for fulfillment of the growing energy needs in the world, it is necessary to discover new energy resources and to fully use those which are already available. Limited amount of diesel and its increased consumption resulted in decrease of the diesel available reserves. Researchers need to concentrate on complete combustion with greater efficiency in the CI engine. Incomplete combustion of diesel in CI engines results in pollution, including the emissions of noxious gases such as hydrocarbons, carbon monoxide and NOx. In CI engines, specific fuel consumption is more and break thermal efficiency is mostly low. Previous research carried out so far on the blending of nanoparticles in diesel and biodiesel has found a reduction of specific fuel consumption and increase in thermal breaking efficiency with a decrease in harmful gas emissions. Nano-particles have been discovered to act as a catalyst when mixed with diesel and biodiesel in the chemical reactions going on inside the engine. Nanoparticles such as Al2O2, CNT, and CeO2 are now used as additives and have shown positive results. This paper presents a review of the existing state of research being carried out in this field.

Day by day, the ministrations of electronic devices have been drastically increased which cause increases the problem of heat dissipation from their due to less surface area. A major channel in such kind of electronic device is to maintain the working temperature below the threshold temperature. The present study demonstrates the numerical simulations to analyze the effect of different aspect ratios and heat flow in a rectangular shape micro-channel. The present study used water as a working fluid. A 3-D rectangular micro-channel is used in this study by applying the four different heat fluxes on the wall. The simulations have been carried out using the commercial software ANSYS Fluent 19.2. The outcomes of this study are shown that the velocity at the micro-channel wall changes considerably with increasing the aspect ratio along the length. The aspect ratio is not much affected. Next, the heat transfer rate through micro-channel at various aspect ratios has been analyzed by numerical simulation.

Three phase inverters are commonly used in renewable energy applications. Boost converters have been used in application domains of wind and photovoltaic. The architecture and implementation of a solar photovoltaic (PV) converter: boost converter and SPWM inverter used to power an irrigation water pump are described in this paper. The inverter receives the boost converter output. The inverter output is routed to a three phase alternating current induction motor, which drives the pump. The inverter can be used in two modes: one that uses the MPPT (Maximum Power Point Tracking) technique, in which the dc-dc converter is controlled so that the solar PV panel is always operating at its maximum power point, and an added mode that stabilises the flow rate of the pump by varying the speed of the motor via an inverter. This paper correspondingly deliberates the inverter's architecture and the control strategy employed.

A Slender body is defined as a body that has a length much greater than the diameter. Due to the low slenderness ratio, slender bodies have found a lot of applications in their favour. The main advantage of these bodies is the ability to overcome the drag due to the oncoming fluid. The main applications of slender bodies are bullets, aircraft fuselage, missiles, rockets and many more. In this study, computational flow modelling has been done to analyze and investigate the flow physics over the slender body. Three different geometries have been generated to study the impact of geometry on the flow. All three geometries are based on the nose cone design, i.e. pointed tip, rounded tip, and ogive tip. The mesh independent study has been conducted to optimize the computational mesh to obtain favourable results. The computation has been done on FLUENT, a premier CFD solver on ANSYS. All the three geometries were simulated for rotating cases at the zero-degree angle of attack (AOA). The turbulence model used is k-ω SST. The results have been obtained in the form of velocity contours, Wall Shear Stress (WSS) contours, wall temperature distribution curves, and the Q criterion. The results are compared between the three models. Significant coherence in the fluid properties of the flow past slender bodies can be observed as the bodies are symmetric.

Ongoing control and monitoring of greenhouse factors can be considered an important part of production practices. The growth rate of plants is greatly affected by the surrounding effective climatic conditions, but to achieve this requires expensive and complex equipment. Traditional systems require excessive effort to connect and handle the converter and its control system. One of the reasons it is expensive is that the system requires extensive power and data cables to and from sensors and control systems. Additionally, for users such as growers and corporate growers who have difficulty monitoring and controlling their systems from any remote location, the application system may only be controlled from a control room or the like. To overcome these shortcomings, this proposal aims to describe how creative greenhouse control systems can be described as event-based systems, where all control actions are primarily expedient compared to events formed by the uncertainty of surrounding elements. The proposed control system provides a cost-effective, low-maintenance solution and delivers excellent performance results. The solution also ignores industry's over-reliance on today's manpower.

The vapor refrigeration systems are extensively used in a range of applications, such as air conditioning, refrigeration, cooling equipment, and ice makers. As air conditioners use vapor compression refrigeration technologies, air conditioners are necessary for human comfort. An air conditioner aims to regulate the temperature in a space such as an office, a mall, a restaurant, or a data center. Many air conditioners are in use around the world now, and their use is growing by the day, directly showing electricity usage and generating the largest power consumption when considered to other electronic domestic gadgets; this energy is produced from power plants whose emissions are released into the atmosphere; whose production demands are increasing daily, resulting in pollution and a negative impact on natural resources like coal and petroleum, which are utilized to power these facilities. If the amount of energy used by air conditioners reduces, the need for electricity produced by fossil fuels falls, and natural resources are preserved for the future. It is vital to improve the air conditioner's performance. This paper examines the various applications of heat pipes, with a focus on enhancing the efficiency of air conditioning systems. Different heat pipes are shown and examined for their use in improving the performance of vapor refrigeration systems, as well as their energy saving potential.

As a pathogen, atherosclerosis is still ambiguous, and it's unlikely that any single procedure will be able to ascertain it as the sole cause. Several factors play a role in the progression of atherogenesis. Genetic inheritance, ethnicity, sexuality, food patterns, and hormonal illnesses are one of the variables that impact cholesterol and lipogenesis. In this study, 4 different artery models were designed with diverse degrees of blockage i.e., 0, 30, 70, and 90%. All of those models were simulated with Ansys fluent software and required numerical data were extracted. Varying degree of stenosis models was simulated to locate the maximal atheroma progression region. The effect of blood flow on coronary artery stenosis was studied by extracting pressure, velocity, and WSS contours. The result depicts us that weak velocity and minimal WSS is the main reason for the development of plaque as blood oscillation is significant in the region. As stenosis progresses, more will be the likeliness of rupture of arterial walls as maximal velocity and WSS will be applied to the stenotic region. Also, due to recirculation, there will be weak velocity and WSS after the stenotic region.

This study numerically analyses the aerodynamic parameters of a base facing triangular cylinder having base length, D in the proximity of a wake splitter plate of Length, L. The gap between the apex of the triangular cylinder and splitter plate is kept as ‘G’. Simulations were done to analyse the effect of G/D and L/D ratios on the coefficient of lift (Cl), drag (CD), and Strouhal number (St). 2-D laminar incompressible flow is analysed at a Reynolds number value of 100, and L/D = 0.5, 1, 1.5, 2.0 at varying gap ratios (G/D) 0 to 4.0. Results indicate that the aerodynamic coefficients are significantly affected by the position of the splitter plate and its length. For L/D ratios 0.5,1.0 and 2, there exists a critical gap ratio at which a sudden jump is observed in the aerodynamic coefficients. Within the parametric space studied, it is also observed that the maximum reduction in Clrms and $$\overline{{C}_{d}}$$ is reported at L/D = 2 and G/D = 3.5.

The growing trend for alternate fuel for transportation makes a huge demand for biodiesel in the market. However, the market price of biodiesel is not competitive enough to compete with fossil fuels. One of the reasons is the production cost and the complexity involved in the biodiesel production technique. In this regard, the production of biodiesel through a wet wash in batch process involves the consumption of a large quantity of water which is used for washing of crude biodiesel. This research has been aimed at making the post-biodiesel washing process more effective by using dry wash filtration technique. Reverse osmosis membranes and various other filter membranes of different materials such as coal, limestone, sand and soil in both coarse and fine size were used to do the comparative study using Ansys Fluent Computational Fluid Dynamics solver. The multiphase fluid flow through porous medium simulation was executed and examined by the obtained contours such as pressure, velocity, viscosity and volume fraction of individual molecules. The retentate and penetrate of each molecule through the porous medium were traced from the volume fraction.

Biofuels are renewable fuels, which can meet the demand of the recent fossil fuel crisis as well as curb the pollution rise due to population explosion. This research focuses on the utilization of aquatic plants as a raw material for the production of biofuel. In this regard, water hyacinth is considered for the investigation. Water hyacinth is also known as Eichhornia crassipes, a biomass, that grows in water body. The plant is collected from Rachenahalli Lake of Bengaluru, India, which is synthesized as raw feedstock under optimal conditions. The method used for the production is trans-esterification where the alcohol used is methanol, and the catalyst is KOH. Using separatory funnel, the biodiesel and the glycerol are separated. The produced biodiesel is then tested in laboratory for density, viscosity, flash point, and calorific value for characterization. Later, water hyacinth biodiesel produced is compared with biodiesel standards to estimate its potential as an alternative fuel.

The current study is an attempt to experimentally realise the effect of seam angle on the dynamics of a cricket ball. A new cricket ball with one of its sides roughened was tested inside a subsonic wind tunnel. Pitot tube readings were made use of to quantify the velocity values near different points on the ball for the same purpose. A novel technique of traversing the pitot tube inside the boundary layer and simultaneously imaging the change in meniscus readings in the connected manometer was used in the study to retrieve the velocity values. The technique holds the advantage of providing velocity values at equidistant intervals within the thickness of the boundary layer. A higher frame rate of recording and slower traversal of the pitot tube will result in higher number of data points. Results from the current study show that the separation regime inside the boundary layer near the point considered gets enhanced with the change in angle of the seam. The effect is found to become more pronounced moving downstream along the circumference of the ball.

Energy consumption and economical country’s growth are interwoven, and rising energy levels always represent rising energy consumption. Coke is a reducing agent and a load-handling tool in blast furnaces. Steel is produced at a lower cost because the coke ovens use less specific energy. In this work, flow of coke oven gas is reduced by using rectification of undercharging of oven, and the flow of coke gas is saved up to 200 Nm3/hr without any disturbing the coke quality. Also, coke oven gas flow reduces from 19,400 Nm3/hrs to 19,200 Nm3/hrs in coke plant, without additional human and physical resources.

With a rise in pollution on a daily basis, there is a need for renewable energy sources. One of the promising renewable power sources is Proton Exchange Membrane (PEM) fuel cell. In this, air and hydrogen feed, flow, and heat/water control are the elements of the reaction of the system. The supplied pressure is maintained by the cathode side of the PEMFC. The problem is with variations in operating temperature and pressure, its output voltage/current gets adversely affected. Thus, there is a need for a suitable robust control design to enhance its dynamic performance. In this work, the time domain first order model of the PEMFC is used. The uncertainty modelling of the fuel cell is done. Further, robust PID and inverse response compensator control designs are carried out using MATLAB. The simulation results indicate that the effect of the variations in manifold pressure is effectively controlled by an inverse response compensator. The step response is utilized to judge the performance of the proposed fuel cell system with a controller.

Energy demand is increasing day by day alongside the increased level of pollution due to combustion of conventional energy sources available. This increasing energy demand led us to find some alternate energy resources such as Biomass, Solar energy, Wind energy. Biomass is one of the most abundant sources of energy, which is easily available. During this review, firstly the biomass (mainly lignocellulosic biomasses) and its availability are being studied by taking into the consideration of pre-processing requirements to produce useful energy. Afterwards, the methods to convert biomass into useful energy were studied. Lastly, the tar elimination approaches were studied by using catalysts.

A numerical examination was conducted in this work to evaluate the performance of the supersonic variable area steam ejector. The performance of a two-stage ejector (TSE) was compared to that of a commonly used single-stage ejector using a 2D-axisymmetric model (SSE). The turbulence model k-ω (SST) was used. The geometries of the ejectors (TSE and SSE) were calculated using the constant rate of kinetic energy change (CRKEC) method. Under both on- and off-design scenarios, numerical analysis was performed. Under on-design conditions, numerical studies showed that the TSE delivered high entrainment ratios of up to 50% when compared to the SSE. With increased exit total pressure, the entrainment ratio of both ejectors falls, whilst the entrainment ratio of the induced flow total pressure increases.

The dimples are most commonly used in electronic cooling devices to enhance the transfer of heat. The fluid flow features of non-uniform radius circular dimples with two different arrangements were analyzed in this paper. The testing was performed with air as the cooling medium in laminar forced convection constraints. For various inlet air flow speeds, the average Nusselt numbers and overall heat transfer for various dimple configurations were recorded. In comparison to the first case, the heat transfer rate and heat transfer coefficient were found to be large for the surface with the dimple radius decreasing in the direction of flow (Case b). For prediction, an artificial neural network (ANN) was employed. The sigmoid function yielded the best results. The findings also demonstrated that RSM and ANN were excellent modelling techniques, with good accuracy. In addition, ANN prediction performance was somewhat better than RSM prediction performance.

In this study, the working of heat pump system used for water heating by taking utilization of solar energy to save environment from pollution and to reduce utility bills for domestic purpose is studied. This experiment includes the flat plate collector consist of serpentine tube, single glazed glass insulated with glass wool is used and the storage tank of 60L capacity with copper condenser helical coil, compressor and R134a refrigerant is used to perform the experiment. Throughout the experiment that the solar radiation of 320 W/m2 heats up the water in 46 min, and there is 7 ℃ difference between the flow of refrigerant in the uppermost and bottommost of condenser coil. The system is designed in such a way that it is feasible to work in the winter season too.

In this paper, a hexagonal-shaped triple-band notched ultra-wideband (UWB) MIMO antenna is designed. The proposed MIMO antenna design is operating for 3.1–13.7 GHz impedance bandwidth for UWB applications. To achieve triple band notches, each hexagonal-shaped radiator is composed of one inverted L-shaped slot, one modified G-shaped slot and a pair of square-shaped EBG structures. The inverted L-shaped and modified G-shaped slots are accountable for the generation of dual notch band characteristics at 3.59 GHz (WiMAX), 5.43 GHz (WLAN) and the proposed antenna produces third notch band characteristic at 10.8 GHz (X-band Broadcasting) using a pair of square-shaped EBG structures. The proposed MIMO antenna design is customized over FR4 (lossy) substrate material having a compact size of 28 × 18 mm2, and the isolation between radiators is acquired by introducing the T-shaped strip on back side of substrate. However, a tapered micro-strip feed is connected with hexagonal-shaped patch above substrate layer to achieve the wider impedance. Therefore, the designed proposed MIMO antenna is having high isolation and efficient notch-controlling capabilities. The designed MIMO antenna's diversity performance is evaluated using different parameters like the envelope correlation coefficient (ECC) and diversity gain (DG). The proposed MIMO antenna has rejection capability for applications like as, WiMAX, WLAN and X-band Broadcasting. The proposed ultra-wideband MIMO antenna with rejection capability can be utilized as communication link in the sensor network and WBAN applications.

Refueling with hydrogen requires many changes to the car’s fuel system. Hydrogen batteries produce oxygen and hydrogen from water through electrolysis. This article experimentally investigated the effects of hydrogen–hydrogen–oxygen (HHO) gas on the emissions and performance of a BAJAJ PULSAR 150 cc four-stroke gasoline engine. The HHO fuel cell generator was designed and manufactured to produce the HHO gas required to run the engine. The HHO gas is blended with fresh air in the intake manifold. Engines using HHO gas have better thermal efficiency, engines consume less fuel, and engines using HHO gas produce fewer harmful gases. HHO generators like this improve the environment and socially acceptable fuel consumption and fuel consumption.

The paper investigates the flow over a heated square cylinder and investigates the variation of mean coefficient of drag ( $$\overline{{C}_{D}}$$ ), Strouhal number (St) and the mean Nusselt number around a square cylinder (Nu) with respect to the Richardson number (Ri). The analysis was done using an in-house finite volume code using projection method with immersed boundary method. Results are presented for flow at Re = 100 and 0 ≤ Ri ≤ 0.2.

Digital processing units generate a large amount of heat during their operation, which causes the warming of substituent electronic components. If the surge in temperature of these components goes beyond certain permissible limits, there may encounter thermal damage to the system. Therefore, the thermal management of the electronic component is essential to ensure the safety and reliability of the unit. Out of the several methods of electronic cooling that emerged over the last few decades, two-phase direct immersion cooling serves as one of the most trusted and effective cooling arrangements to resolve the overheating issue. Even though two-phase DIC works in the nucleate boiling regime, the knowledge of system behavior in the film boiling regime is essential for its designing purpose. The observations of the present numerical study are dedicated to the analysis of film boiling behavior of overheated surfaces when these are exposed to forced convection configuration. The analysis characterizes the interfacial dynamics by an interplay of buoyancy forces and inertia forces exerted by the motion of the saturated liquid. The investigation further illustrates the dependency of the film boiling heat transfer coefficient on the characteristic dimension (D), surface superheat (∆Tsup), and arrangement of heater surfaces. It has been established that for elliptical surfaces, phase change heat transfer is maximum when the major axis of the ellipse is aligned with the direction of saturated liquid cross-flow.

This study compared the different designs of solar energy-based water purification systems [such as single base single slope passive (SBSSP), single base double slope passive (SBDSP), and single base double slope active solar still under natural mode (SBDSAN)] by conducting experiments on these systems at various water depths throughout the year. SBDSAN has a 33.5% and 7.4% yearly return, respectively, when compared to SBDSP and SBSSP. Theoretical modelling for a double-slope solar still was put to the test, and the theoretical and practical results were found to be quite close. The coefficients of correlation for the inner and outer condensing cover temperatures, water temperature, and distillate yield were 0.9975 (inner east facing), 0.9832 (inner west facing), 0.9660 (outer east facing), 0.9753 (outer west facing), 0.9947, 0.9054 (east side), and 0.8959 (west side), respectively.