Recent Advances in Chemical Engineering

The convective heat transfer coefficient of nanofluids in a channel has been numerically studied for the laminar flow condition. The channel has been confined with inline noncircular tubes. The computational channel has aspect ratios of 10 × 0.66 cm2 with five different circular and non-circular tubes placed in series one after another. The 2D numerical simulation has been solved for different Reynolds number (Re) and the heat transfer coefficient and pressure drops were determined. A custom field function has been written to calculate the entropy generation. The simulation results showed that the Nusselt number and the heat transfer coefficient enhanced with the increase in nanoparticles concentration in nanofluid. From the entropy generation results, it can be predicted that entropy of system increased as concentration of nanoparticles increase. Entropy of the channel with obround tubes was found to be much higher than other geometry of tubes (circular, oval, diamond and rhombus).

This paper encapsulates the results of a numerical investigation based on heat transfer and fluid flow characteristic of water through a two-dimensional model of an isothermal-fluxed circular duct with alternating inclined ribs. The effects of artificial inclined rib’s roughness on heat transfer and fluid flow have been investigated. A 2-D numerical simulation is performed using the ANSYS FLUENT 15 code. The simulation is conducted in order to gain an understanding of physical behaviour of the thermal and fluid flow in the duct fitted artificial inclined ribs under constant wall temperature conditions for all three flow regimes—Laminar, Transitional and Turbulent; that is, for the Reynolds number ranging from 200 to 20,000. The Navier–Stokes equation in common with an energy equation is solved using the SIMPLE technique with Shear Stress Transport (SST) k–ω turbulence model. The heat transfer and thermal performance of the inclined ribs at various attack angles (θ) of 15°, 30°, 45° and 60° with different Reynolds number (200–20,000) are studied and compared with those of a plain isothermal-fluxed circular duct. The Nusselt’s number increases with the increase of attack angle (θ = 15°–60°), also increase of Reynolds number. All ribs at different angle of attack (θ = 15°, 30°, 45°, 60°) have good thermal performance with greater than unity which indicates that the compound heat transfer technique of inclined ribs with different angle of attack is commendable for the maximum enhanced heat transfer rate for higher Reynolds number.

Vortex dynamics plays a vital part in the transport of mass, momentum and energy of a flow field. Vortex manipulation is the way out for controlling any device that involves mixing of flow. In the present study, the size of recirculation zone behind the various non-circular geometries and various square blocks of different thicknesses 4, 6 and 8 mm is visualized. The physics behind the wake zone size manipulation for different Reynolds numbers is also investigated. Flow separation and reattachment points and distance of reverse flow for various geometries are observed and illustrated. Work is further extended for flow visualization over forward, backward and combined steps. Experimental analysis is done by using an open channel setup, which is fabricated to designed dimensions. Drag force and the coefficient of drag for various geometries with different set of inclinations (90° and 30 °) and at various Reynolds numbers are calculated. Plots are made between various Reynolds numbers and coefficient of drag, pressure uphill, reverse flow length and are analyzed with respect to different flow features.

This particular study consists of computational analysis based on transfer of heat and fluid flow characteristic of air with Pr = 0.7 through a 2-D micro-channel of an isothermal-fluxed wall of a circular shape micro mixer. In particular, a simulatory model has been established using computational fluid dynamics (CFD), i.e., Ansys Fluent 14.5 to investigate such effect. The formulations are done by the laminar flow model, since the flow is assumed to be laminar. The simulation is conducted for gaining an insight and understanding the physical behaviour of the thermal and fluid flow of air in the micro channel with built-in circular shape micro mixer under constant the conditions of isothermal wall. The configuration parameters include the, circular diameter (d) and pitch (p). Reynolds number varies from 10 to 800 in this particular study. A 2-D non-uniform grid was generated, in order to critically examine the flow and heat transfer. The effects of Reynolds number, Nusselt number, friction factor, temperature ratio of modified case to base case, are examined and discussed. All micro mixers at different pitch and diameter have good, tempature ratio of modified case to base case, which are greater than unity. It is highly possible to be implemented in the practical application like micro channel heat sink.

This research work was carried out to develop optimum continuous process for the esterification of ethanol with maleic acid by using surface modified sulfonic acid functionalized silica catalyst in a packed bed glass reactor (3 cm ID and 46 cm height) at 80 °C. Optimization of weight of catalyst (gm) and feed flow rate (ml/min) was carried out by using Response Surface Methodology (RSM)—Central Composite Design (CCD). The consistency of statistical model developed by CCD was verified using analysis of variance (ANOVA). The optimum condition for the conversion of maleic acid was 26.42 gm catalyst weight and 3.11 ml/min feed flow rate. The predicted conversion and actual conversion of maleic acid was found to be 47.83 and 46.89 % respectively under the 95 % confidence level of ±0.22. Comparing the conventional batch reactor with packed bed reactor at optimized condition implies that required amount of catalyst per gm of maleic acid is less in PBR. The results obtained shows that the RSM-CCD is adaptable for the maleic acid conversion of current esterification study.

Various devices are used for solids drying. Spouted beds are most suitable for drying coarse granular solids like agricultural grains. Conventional single spout beds suffer from few inherent limitations. The use of multiple fluid inlets and draft tubes in a spouted bed will help in overcoming the limitation of maximum spoutable bed depth so that large scale drying operations are possible. In an operation like solids drying use of porous draft tubes in a multiple spouted bed helps in the lateral transport of hot air from spout to annulus region, thereby providing better contact between solid and fluid phases in annular region as well. As a result higher mean transfer rates of heat and mass in the entire bed may be achieved. In this work a multiple spouted bed with porous draft tubes has been used to carry out wheat drying studies. Batch experiments are conducted using grains having initial moisture contents of 20 and 25 % on dry basis: inlet air temperatures of 40, 50 and 60 °C, air flow rate of 36 m3/h are maintained. Fluid inlet diameters of 8, 15 and 21 mm are used in the study. Moisture content versus time plots are prepared for all runs; from these plots batch drying times needed to achieve a final moisture content of 10 % from given initial moisture content are obtained. The results indicate that the drying occurs under falling rate period under all conditions used. The drying rate is found to increase with increase in initial moisture content and air temperature. The batch drying times is found to be lower for the case of multiple spouted beds with porous draft tubes. The batch drying time is found to be decreasing as the fluid inlet size decreases.

In this study drying characteristics of ginger (raw as well as soaked in water) was investigated by microwave drying method using five different power levels. The drying characteristics of ginger such as moisture ratio (MR), drying rate (DR), effective moisture diffusivity (EMD), energy consumption (EC) and drying efficiency (DE) were studied for ginger samples (soaked and unsoaked). The value of MR reduces quickly and then gradually decreases with augment in drying time. The drying rate increased simultaneously increase in power. Effective moisture diffusivity values increases with increase in MW power levels. The energy consumption is low at lower power level but drying efficiency was higher at high power level. Modified page model was found to be in regression with the experimental data prevailed in this study.

Several conventional methods are employed to remove cationic dyes from waste water. A novel technique based on liquid/liquid extraction using reverse micelles is proposed whereby recovery of solvent and reuse of dye is possible. Single component batch experimental studies were carried out using two dyes, namely Basic red 9 (BR9) and basic violet 3 (BV3). Glycolipids produced naturally using Pseudozyma antarctica from soybean oil medium were used as surfactant. Extraction efficiency of single component system of each dye was investigated by using amyl alcohol as solvent and sulphuric acid as carrier. The process parameters such as dye concentration, sulphuric acid concentration and surfactant concentration on the extraction efficiency were optimized using Box-Behnken design. The optimum conditions were calculated by using Derringer’s desirably.

The need for softer processing of fish oil has become one of the major concerns in the refining industry. The deacidification efficiency of sardine oil/solvent mixture with different solvents was studied. Four solvents methanol, ethanol, propanol and acetonitrile were tested for their ability to deacidify sardine oil. At an oil/solvent ratio of 1:2, maximum reduction in free fatty acids (FFA) of 32.08, 30.8, 23.3 and 10.94 % was noted for methanol, ethanol, propanol and acetonitrile respectively. The influence of various solvent ratios, and their effects on the oil loss were also studied. The efficiency in deacidification was also characterised by the solvent traces in oil and reduced oil loss. Of all the tested solvents, methanol gave the highest reduction in the FFA levels while acetonitrile gave the lowest reduction in FFA.

Conventional thermal evaporation and pressure driven process that is reverse osmosis are widely used to concentrate liquid foods, but they are highly energy intensive and expensive. Forward osmosis which is promising membrane process is extensively studied as an alternative process to concentrate liquid foods. This paper focuses on comparison of thermally concentrated and forward osmosis membrane processes to concentrate sugarcane juice. Forward osmosis (FO) stands next in cutting edge membrane technology to concentrate the sugarcane juice to syrup. The difference in osmotic pressure across the membrane is the driving force for FO, wherein the water from sugarcane juice is transferred to the other side that is to draw solution through the membrane at atmospheric pressure and ambient temperature. The effect of various operating conditions on transmembrane flux for different concentrations of draw solution and the effect of flow rate were studied. At optimum operating conditions, maximum transmembrane flux was determined as 0.79 L/m2 h. The sodium chloride (draw solution) transferred to feed solution was found to be 179.3 ppm which was determined using flame photometer. In the large scale experiment, the sugarcane juice was concentrated from 17.6 to 31.7 °Brix (twofold). Forward osmosis membrane offers energy efficient methods for concentrating raw sugarcane juice when compared to energy intensive evaporative methods. Further, improved FO membrane technologies and new draw solutions will improve the performance of the membrane process.

C-phycocyanin a blue colored pigment from Spirulina platensis is selected as encapsulating biomaterial. This pigment is a phycobiliprotein is used as natural dye and has good therapeutic values. In the present study, C-phycocyanin is encapsulated within calcium alginate gel matrix using microfluidic device. A microfluidic device comprising of two cross-junction channels (100 µm depth, 200 µm width) is designed for encapsulation of the pigment. Micro-fluidic devices have been used for continuous synthesis, control, and characterization of high-quality droplets, in which the synthesis process can deliver mono dispersed size distribution. C-phycocyanin pigment is mixed with sodium alginate solution dispersed through the microfluidic channel. Droplet formed in the microfluidic channel is further reacted with Calcium Chloride at the outlet of the channel. Monodispersed high throughput encapsulated C-phycocyanin was produced with a microencapsulated droplet size of 95-100 μm. The size of the droplet was confirmed by scanning electron microscope. The drop formation mechanism is been studied and compared with the literature. The proposed microfluidic method of microencapsulation is capable of generating high-quality gel matrix of uniform size.

Low grade coal is the cheapest fossil fuel and widely distributed among all over the world. The use of low grade coal producing high ash that leading to environmental pollution due to generation of large amount of solids and gaseous pollutants. Physical beneficiation techniques method may not adequate remove the mineral matter from the coal, so to develop more efficient technologies for production of clean coal. An attempt has been made in the present work tries to upgrade the high ash (over 50 %) Indian coal from MCL (Mahanadi Coal Limited) Odisha, by using alkaline (NaOH) leaching. To study the effect of leaching parameters (time, temperature and concentration) and the particle size for that, the leaching experiments were conducted in a stainless steel batch reactor of 2.5 l capacity with controlled heating facility. Initially, the coal sample with mesh size (−16+100 mesh) was leached with 50–150 g/L NaOH solution at 100 °C for one hour. The maximum percent demineralization was 28 % obtained which at concentration of 100 g/L leaching and further, it decreases at higher concentration of alkali solution due to formation of insoluble sodium complex (sodium-aluminosilicate) which restrict demineralization. The variation of mineral composition in the coal due to the leaching effect of before and after treatment was done by Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray (EDX) analysis. The calorific or heating value of coal also improved by the leaching effect due to the removal non-carbonaceous mineral matter.

Sulphuric acid treated red mud has been utilized for removal of Disperse Orange 25 (DO25) dye from dye contaminated water to investigate its potential as a low cost adsorbent. The activation with concentrated sulphuric acid has increased the surface area of red mud from 20.2 to 32.28 m2/g. The effect of contact time, initial pH, initial dye concentration, temperature and red mud dosage on percentage adsorption of dye using acid treated red mud was investigated. Acidic pH of 4 favoured adsorption and 120 min contact time was found to be suitable for attainment of equilibrium conditions. Langmuir isotherm model has been found to represent the equilibrium data for DO25-red mud adsorption system better in comparison with Freundlich isotherm model. The adsorption capacity of activated red mud was found to increase with the increase in temperature and at 40 °C, it was found to be 127 mg dye/g of activated red mud. Thermodynamic analysis showed that adsorption of DO25 on acid-treated red mud is an endothermic process with ΔHoof 67 kJ/mol. The adsorption kinetics was represented by second-order kinetic model and the kinetic constant was estimated to be 0.00102 g/mg min.

Present study describes the adsorptive removal of Cd(II) ions from aqueous solution using activated carbon prepared from sweet lime peels (a fruit processing industry waste) treated with zinc chloride (ZnCl₂) in impregnation ratio 1:1 (w/w) followed by carbonization at 500 °C for 2 h. The ZnCl₂-activated carbon obtained was characterized by proximate analysis, surface textural characterization, surface charge etc. An effect of pH, temperature and contact time on Cd(II) ion removal efficiency of activated carbon was investigated in batch mode to establish optimum adsorption conditions. Adsorption equilibrium data analysis for the temperature range 303–323 K showed best fit in Langmuir adsorption isotherm. Maximum adsorption capacity was observed to be 110.98 mg g−1 at 323 K. Adsorption of Cd(II) ions on activated carbon followed the Pseudo-second-order kinetics from which activation energy for Cd(II) ion adsorption was determined to be 31.27 kJ mol−1 and indicate the chemisorption phenomenon.

Now a days due to rapid industrialization green house gases are continuously increasing. Carbon dioxide is the major constituent of the greenhouse gas which causes global warming and climate change. The main sources of carbon dioxide emissions are burning of fossil fuels. In our present investigation the main aim is to capture carbon dioxide (CO₂) from flue gas. Adsorption is a cost effective technique to remove pollutants from flue gas. Adsorbent used here is activated carbon. In the present investigation a four stage fluidized bed reactor has been designed and operated in counter-current manner. The effect of superficial gas velocity, solid (activated carbon) flow rate, and the weir height on percentage removal of carbon dioxide (CO₂) in the four stage fluidized bed reactor were investigated. The percentage removal of carbon dioxide was found to be 65 % when the flow rate of the solid is high and the flow rate of gas is low with maximum weir height of 60 mm and inlet carbon dioxide (CO₂) concentration of 3000 ppm at room temperature.

The major factors like rapid industrialization, population explosion and mining have resulted in addition of heavy metals in the aquatic environment much above the tolerance limit and hexavalent chromium is one among them. The present studies involves the use of sweetlime peel powder and lemon peel powder as low cost adsorbent in a fixed bed column from aqueous synthetic solutions for the removal of Cr(VI). The Cr(VI) uptake capacity of sweetlime peel and lemon peel powder were examined as a function of operating parameters like initial Cr(VI) concentration (6, 8, 10 ppm), bed height (2, 3, 4 cm), flow rate (3, 5, 7 ml/min). It was found that adsorption capacity increased with increase in initial adsorption concentration and also increased with decrease in both bed height and flow rate. The fit of various models such as Bohart-Adams, Yoon-Nelson and BDST were tested by applying experimental data gathered from dynamic studies performed in fixed bed column.

Chromium(VI) is one of the main pollutant of the environment. Chromium(VI) is one of most important heavy metal used in various industry. It is most toxic, teratogenic, carcinogenic and probably mutagenic. It is highly soluble and easily accumulated to living organism. Thus Cr(VI) effluents causes very lethal environmental hazards. Since the effect of Cr(VI) on human health and environment is a matter of concern. Therefore it is necessary to remove the Cr(VI) from waste water before disposal. In this study we remove Cr(VI) by using activated carbon derived from saw dust and bark of Eucalyptus, Neem and Rice husk carbon via adsorption process. Adsorption process was investigated as contact time, pH of aq. solution and adsorbent dose dependent (Baral et al. Bioresour Technol 91:305–507, 2008). Acid activation (H₂SO₄) give the maximum percentage yield of activated carbon. So we used H₂SO₄ for the preparation of activated carbon from adsorbents. Potassium dichromate as a synthetic contaminant is used for preparing the aqueous solution for the evaluation of removal potential of Cr(VI) by these adsorbent. The adsorption potential of these derived adsorbents is compared with another adsorbents (Bayat, J Hazard Mater B95: 275–290, 2002). The Cr(VI) concentration was determined by UV spectrophotometer. The batch experiments were conducted for this study (Bhattacharya et al. J Hazard Mater 171:83–92, 2009). Results shows that the maximum Cr(VI) removal 94.33 % was achieved at pH 2.0 with 5 gm of adsorbent dose with 3 h of contact time by saw dust carbon of Eucalyptus. The study demonstrates that SDC, bark (Eucalyptus, Neem) and RHC have the potential to become an effective agent for the removal or Cr(VI) from synthetic waste water. The experiment have isotherm and kinetic study. The study was analyze by Langmuir and Freundlich adsorption isotherms and Pseudo First order and Pseudo Second order kinetic study.

The work highlights efficient utilization of groundnut shell ash (GSA) for various applications. The production groundnut seeds average about 45,654 metric tons across the globe. Those seeds are used as a food material and for extraction of edible oil. The shells of groundnut seeds are waste, having a high calorific value so its potential is tapped in industries and boilers. Subsequently upon the utilization of biomass, the ash, which is produced, is of ample quantity needs to be addressed properly for its chemical, physical properties and its potential application. GSA is a rich source of micronutrients and improves yield, and is spread on agriculture lands as a soil additive. Groundnut shells are a rich source of fuel. From literature study it is evident that the GSA is used for various applications like stabilization of black cotton soil, adsorption, as a concrete admixture. For the first time, GSA has been evaluated as an adsorbent for 2,4-D removal from aqueous solutions and as a soil additive. GSA was characterized extensively by X-ray fluorescence, BET surface area and SEM image. Results of XRF analysis showed that GSA can be used as a rich source of micronutrients such as MgO, Al₂O₃, SiO₂, K₂O and CaO. 2,4-Dichlorophenoxyacetic acid (2,4-D), a commonly used pesticide, was chosen as a representative adsorbate for studying the effects of various parameters in batch adsorption. BET surface area is found to be 22 m2/gm. SEM image shows a very rough and irregular structure of the GSA surface. Batch adsorption experiment studied to find the effect of adsorbent dose, initial 2,4-D concentration, and equilibrium time. Based on the batch results dosages of GSA/hectare have been recommended for different crops to serve the dual purpose i.e., as an adsorbent and a soil additive.

The aim of this work to synthesize ZnO/palash flower powder nano catalyst using single pot process and compare their effectiveness for degradation of phenol under identical experimental conditions. FEG-SEM micrograph shows that maximum spot of nano scale identity in their morphology. XRD results shows prepared ZnO nanocatalyst are hexagonal in crystal structure with mean particle size 17.4 nm. FTIR results shows ZnO transmittance band at 449 cm−1. EDAX confirm the presence of Zn and O in sample. Phenol degradation was 62 % at 4 h reaction time, 30 °C reaction temperature and mass loading of catalyst was 1.0 g/L for aqueous solution of phenol. Synthesized nanocatalyst was more economic and ecofriendly.

The Advanced oxidation process using the hydroxyl radicals is an emerging method in water and wastewater treatment. The oxidative potential of ozone is 2.07, whereas for ozone it is 2.80 V which is higher than the conventional oxidants. However, the reaction with molecular ozone is selective to certain organic and inorganic compounds. But, the hydroxyl radicals can readily react with these compounds through radical-radical reactions, hydrogen abstraction, electron transfer and electrophilic addition which can completely mineralize the pollutant and their intermediates. Quantitative measurement of the hydroxyl radical concentration is rather difficult due to its low concentration. A few computer models have been developed for the prediction of concentration of hydroxyl radicals. An indirect method of the measurement of the concentration of hydroxyl radical is developed which works with a probe compound. Concentration of hydroxyl radicals generated from ozone microbubbles was determined by using this indirect method for pH 3–10. p-Chlorobenzoic acid (PCBA) was used as the probe compound to calculate the concentration of hydroxyl radicals. A constant, R _ct , was defined as the ratio of ∙OH and O₃ exposures, which was employed to estimate the concentration of hydroxyl radicals. It was observed that the O₃ exposure and the depletion of PCBA were higher at acidic pH than at the alkaline pH. The feasibility of the method was calculated by detecting the depletion of phenol. The fractional contribution of hydroxyl radical and molecular ozone was calculated by this method.

In the present study, photocatalytic experiments were performed to investigate carbofuran removal from aqueous solution. The investigation was conducted in a batch-mode photocatalytic reactor. A novel granular activated carbon supported titanium dioxide (GAC-TiO₂) was prepared and utilized in this investigation. Batch experiments were conducted for 240 min at a constant carbofuran concentration (250 mg L−1) and at varying GAC-TiO₂ concentrations (as TiO₂, 5 and 75 mg L−1) and pH (3, 7 and 11). Around 83 % carbofuran removal was observed at pH 7 and 75 mg/L TiO₂ concentration after a reaction period of 240 min. Similar carbofuran removal (84 %) was observed under pH 7 and 5 mg/L of TiO₂ concentration. On the other hand, the increase in pH from 7 to 11 and the simultaneous decrease in catalyst concentration from 75 to 5 mg/L enhanced the carbofuran removal from 83 to 100 %. The photocatalysis process conducted at acidic pH (i.e. pH 3) and 5 mg/L TiO₂ concentration has shown a carbofuran removal of 77 %. The change in TiO₂ concentration (i.e. from 5 to 75 mg/L) at pH 3 has not produced any significant increase in the carbofuran removal. The results show that carbofuran removal by photocatalysis was more favored under alkaline pH compared to neutral and acidic pH conditions. The overall observations indicate that the combined form of GAC-TiO₂ could be effectively used for efficient treatment of carbofuran contaminated water in a batch-mode photocatalysis system.

TiO₂/Ni-P composite electrode has been fabricated through electrodeposition from an optimized Ni-P alloy plating bath loaded with titanium dioxide (TiO₂) nanoparticles, using glycerol as the additive. TiO₂/Ni-P composite coatings were developed on copper rod from optimal bath of Ni-P alloy, and their electrocatalytic behaviors have been studied in alkaline medium (1.0 M KOH). The electrocatalytic behaviors of TiO₂/Ni-P composite electrodes for water splitting reactions of hydrogen evolution reaction (HER) was studied by cyclic voltammetry and chronopotentiometry techniques. Experimental results revealed that addition of TiO₂ nanoparticles (p < 25 nm) into the bath has significant effect on the electrocatalytic behavior Ni-P alloy deposit. Experimental results demonstrated many fold increase in the electrocatalytic activity of Ni-P alloy coating after the incorporation of TiO₂ nanoparticles. The enhanced electrocatalytic activity TiO₂/Ni-P composite coatings were attributed to the TiO₂ nanoparticles intersticed in the deposit matrix of the coating, evidenced by FESEM, EDX and XRD analyses. The experimental results were discussed with possible mechanism, responsible for increased hydrogen evolution due to its reduced overvoltage.

TiO₂ nanosheets were synthesized from tetrabutyl titanate precursor via solvothermal treatment using Hydrofluoric acid as structure directing agent. Anatase phase nanosheets could be obtained by this method, imparting good photocatalytic activity. In order to enhance photocatalytic activity, silver doping of TiO₂ nanosheets was done using photo-deposition method under ultra-violet light irradiation. These nanosheets were characterized using Transmission electron microscopy, X-ray diffraction and Energy-dispersive X-ray spectroscopy. Photocatalytic activity was estimated by means of congo red dye degradation studies under ultra-violet light irradiation. The silver doped TiO₂ nanosheets showed enhanced photocatalytic activity.

TiO₂/MgO nanocomposites were prepared and was characterised by TEM. The TEM analysis showed that the photocatalyst was of nano size. The electron hole pair recombination found by using TiO₂ nanoparticles alone can be minimized by using the TiO₂/MgO nanocomposite and can enhance the degradation efficiency of the photocatalyst in the degradation process. The nanocomposite was found to completely degrade the organic azo dye. The photocatalytic degradation process was undergone in a photocatalytic reactor with UV light irradiation. Degradation of the dye solution were analysed by FTIR analysis. The frequencies at which there are the absorptions of the IR radiation in the FTIR spectrum can be related to the bonds in the compound. Therefore, FTIR spectrum can be used as a confirmation for degradation of the organic dye.

A simple co-precipitation method was used for the synthesis of visible light assisted photocatalyst zinc titanate (ZnTiO₃) nano particle powders. The powder synthesized was analyzed by means of Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and the decomposition temperature was analyzed by using Thermogravimetric analysis (TGA). The particle size of the prepared zinc titanate was calculated by using Scherer equation and it was found to be 100 nm in size. An aqueous solution of methyl orange was used to study the photocatalytic efficiency of the prepared zinc titanate nano particles. The results confirmed that the zinc titanate nano-particle display excellent photocatalytic efficiency in visible range radiation.

Wet scrubbers are most important air pollution control devices used in many chemical process industries to remove particulate and acid gases from off gases. Plate scrubbers are medium level energy scrubbers, simple in design and they can be used for the removal of acid gases from the exhaust gas streams which are being released into the environment from various chemical industries. The primary particle removal mechanisms in scrubbing systems are well known where as the actual mechanism which is occurring exactly in the dual-flow sieve plate system is not yet discovered. It is most important to predict the particulate removal capacity of the system to select air pollution control device. Therefore, theoretical estimation of the column efficiency with the model is essential. This paper tries to predict the three stage dual-flow sieve plate column scrubber efficiency theoretically for 1-10 µm range fly ash particles. Dual-flow sieve plate column scrubber particle removal characteristics are analyzed by observing the gas flow rate, liquid flow rate and size of particle effects on overall efficiency. By using the concepts of diffusion, impaction and interception, the particle removal mechanism is analyzed theoretically. A mathematical model has also been suggested to predict the particulate removal efficiency in the dual-flow sieve plate column. More than 100 % removal efficiency is observed for more than 3.5 µm particle size.

Venturi scrubber is very effective device for air pollution control. In an industry venturi scrubber is very efficient to remove micron size dust particles by injecting water droplet. Dust particles collide with the water droplet by inertial impaction at the throat section of venturi scrubber and deaccelerated at diffuser section to allow pressure recovery. Performance of venturi scrubber is assessed in terms of collection efficiency and pressure drop. Venturi scrubber is mostly used in Filtered Vented Containment System (FVCS) for removal of radioactive fission products in Nuclear power plant in severe accident. The purpose of the present study is to design a venturi scrubber to achieve a high overall efficiency in removing radioactive particulate iodine- 131 by CFD simulation. Mesh is developed by Gambit 2.4.6 and Ansys Fluent 15 is used to predict the pressure drop profile inside the venturi scrubber. From a physical point of view, scrubbing process follows liquid injection, the droplet formation, droplet break up and particle capturing mechanism. TAB model is considered to predict the droplet break up. Iodine of diameter 1 µm is used as dust particle. Flow field inside venturi scrubber is simulated by K-ε Turbulence model and trajectory of dispersed particle is modelled using lagrangian frame of reference. Finally the results shows the effect of gas velocity and liquid mass flow rate on pressure drop and this study also investigates the overall collection efficiency of venturi scrubber for different throat gas velocities and various mass flow rate of liquid inlet.

The use of supercritical fluid extraction (SCFE) has become progressively popular due to its effectiveness in extraction and separation of the solute components. CO₂ is the most commonly used supercritical fluid (SCF) since it is non-toxic, non-flammable, relatively inexpensive, and chemically inert and its critical parameters can be attained with moderate ease. Bitumen, a mixture of hydrocarbons with a broad array of carbon numbers, sizes, and chemical structures can’t be extracted and separated easily using the conventional technologies. In this paper the theoretical investigation on the SCFE of bitumen using CO2 has been done. A mathematical model has been developed to study the temperature and concentration profiles in the bitumen bed. Further molecular dynamics simulation studies are being envisaged.

Methanol crossover and water crossover within the polymer electrolyte membrane of a passive direct methanol fuel cell (DMFC) has been analyzed in the present study. A non-isothermal mathematical model has been developed. The model incorporates methanol, water and oxygen transport phenomena along with electrochemical reactions occurring in the DMFC. The model also considers the variation in the cell operating temperature and its effect on species transport and electrochemical reaction during the cell operation. The mathematical model is validated with the experimental results.

The focus of the current study is to propose an improved Zeigler-Nichols method for tuning the PID controllers for unstable First Order plus Time Delay (FOPTD) systems. In the proposed method, the controller settings are obtained by solving the magnitude and phase angle criteria. The addition of the controller modifies the overall gain of the system, subsequently changing the values of the controller gain. A second iteration for calculating the updated controller gain is conducted by solving the system’s magnitude and the phase margin criteria, incorporating the Proportional-Derivative-Integral controller transfer function, with unity proportional gain, and with the values of reset time and derivative time. A number of FOPTD systems with varying time delay to time constant ratios are simulated by using the proposed method. A non-linear model of a bioreactor is also simulated to show the enhanced performance over the other methods present in literature. The proposed method significantly improves the performances for the servo and regulatory problems.

Higher order transfer function models are approximated by a three parameters models such as critical damped SOPTD and FOPTD models. A design method for centralized PID controllers using Tanttu and Lieslekto method for the identified critical damped Second order plus time delay (SOPTD) is proposed. Centralized PI controllers are designed by the Tanttu and Lieslekto method from the identified First order plus time delay (FOPTD) model. The Centralized SOPTD-PID control system gives enhanced main responses and lesser interactions. This improvement is shown for TITO systems having high interactions (λ₁₁ > 1). The robustness study for the controllers is carried out by using the Inverse Maximum Singular Value versus Frequency plot for the input and output multiplicative uncertainties. Simulation results are given for one TITO system having λ₁₁ > 1. The centralized SOPTD-PID controllers give improved results in comparison with the centralized FOPTD-PID/PI controllers.

A non-linear heat conduction problem is considered to identify the Robin coefficient using inverse analysis. The coefficient of heat transfer representing the corrosion damage, which is time dependent, is estimated for the surrogated data. The mathematical model is discretized using finite difference method and implicit scheme is incorporated for temperature time history. The Bayesian framework is applied to obtain the best estimates of unknown parameters and the standard deviation provides the useful information about uncertainty associated with the estimated parameter. The sampling space is explored using a powerful Metropolis-Hastings algorithm. The maximum a posterior, mean and standard deviation are obtained based on 10,000 samples. Results prove that Bayesian Inference approach does provide accurate parametric estimation to the inverse heat problem.

Transesterification of vegetable oil is very widely used in the synthesis of methyl esters of fatty acids. These methyl esters found numerous applications in the preparation of various oleo-chemicals having commercial importance. In this study, a mathematical model, which is available in open literature, was used to study the kinetics of non-catalytic batch transesterification of cottonseed oil using methanol. The model is based on the reversible mechanism of the transesterification reaction. A Visual Basic Programming code has been developed to solve the differential equations involved in the study of kinetics of transesterification reaction using Euler’s Method. The effects of the operating parameters such as molar ratio between the triglyceride and alcohol and temperature on the conversion rate were also studied. The simulated results show good agreement with the experimental data available in literature.

Propylene Oxide, also known as Epoxypropane is one of the significant organic compounds produced in chemical industries. Propylene Oxide finds major application in the production of polyether polyols and along with diisocyanates is used to produce polyurethanes. Traditional production methods involve Chlorohydrin process which is slowly replaced by other processes because of large disposal problems. Major alternative production routes include Hydroperoxide process, Cumene process etc. The present work is focussed on process development for production of Propylene Oxide using Hydroperoxide process. Hydroperoxide process is based on the peroxidation of Ethylbenzene to Ethylbenzene hydroperoxide which in turn reacts with Propylene producing Propylene Oxide and alcohol. Kinetic data and operating conditions for the main reactions, namely peroxidation and epoxidation were obtained from available literature. A spreadsheet tool was developed to perform material and energy balance of the process without recycle operation. Basis for the process was chosen as 100 kmol/h. Multicomponent distillation column was designed using Fenske-Underwood-Gilliland correlations. Adiabatic plug flow reactor for epoxidation reaction was also designed considering the reaction as first order gas phase irreversible exothermic reaction. Simultaneous ODEs were solved in Scilab 5.5.1 for designing the reactor. Further, the entire process flowsheet was also simulated using Aspen Plus (V8.6, Aspen Tech, Inc., USA) and the results obtained were compared with that of spreadsheet appropriately. Aspen Plus was also used to collect thermophysical properties of components involved and to decide the operating conditions for the process specifically for flash drum and distillation column. Assuming 1 % entrainment from equipment, effluent treatment analysis was carried out and environmental factor (E factor) was computed and compared to a typical petrochemical industry.

In the present study, the occurrence and intensity of natural convection in air or water filled as medium in a diamond shape cavity is evaluated as a function of Grashof number. Grashof number represents the buoyancy force effect which leads to the natural convection or circulations inside the cavity. In the context of granular material, diamond shaped cavities or voids are present between the granules. Depending on the shape of granules, the voids also can have various types of boundary shapes. For simulation purpose, a two dimensional diamond shaped cavity is chosen (a square turned 45°). The left and right boundary temperatures are assigned different values corresponding to side wall heating. The gravity direction is considered as four possibilities: positive y-direction, negative y-direction, positive x-direction and negative x-direction representing various configurations of wall heating. These situations correspond to earth’s gravity or centrifugal acceleration. The walls of the cavity are maintained at a temperature difference of 10 °C. The size of the cavity is varied and the maximum velocity magnitude in circulations is obtained for different directions of the gravity using COMSOL Multiphysics. The results of velocity field or circulations are graphically represented and analyzed as a function of Grashof number. It was found from simulation results that the intensity of natural convection is highest for gravity in vertical direction and for air as compared to water.

Microchannel heat sinks are highly efficient cooling devices in electronic field. In this study, heat transfer characteristics of CuO–H₂O nanofluid flowing through a microchannel having dimples/protrusions, were investigated using CFD package FLUENT 15.0. A constant heat flux of 5 × 105 W/m2 was uniformly applied on all four walls. Nanofluid enters the microchannel at 300 K under fully developed flow conditions. SIMPLE (Semi Implicit Method for Pressure Linked Equations) algorithm was used in the solution procedure. A second-order upwind scheme was used to solve the momentum and energy equations. The dimples/protrusions are arranged on the wall of microchannel either in aligned or in staggered manner. 3-D numerical simulations were carried out at various Reynolds numbers (100, 300, 500, 700). The heat transfer characteristics were obtained for various geometries by varying inlet velocity (1.2–8.7 m/s) and volume fraction (0–4 %) of nanofluid. Wall temperature of microchannel was found to be lower for higher values of velocity and nanoparticle volume fraction, indicating better transfer of heat from wall to fluid. The enhancement in heat transfer was evaluated by a parameter known as thermal performance (TP) which is a function of Nusselt number (Nu), friction factor (f). Entropy generation rate was determined to find optimal geometry. It was found that microchannel with dimples and protrusions and 4 vol.% CuO nanofluid gave the maximum heat transfer enhancement.

CLC is a promising cost effective, energy efficient technology that helps to separate CO₂ from the flue gas, with the aid of an oxygen carrier. It helps to reduce the atmospheric CO₂ concentrations, which is essential as per present environmental scenario. Chemical looping combustion process involves two reactors, namely air and fuel reactor, where subsequent heterogeneous oxidation and reduction reactions take place. In air reactor, metal gets oxidized to metal oxide reacting with inlet air, whereas in the fuel reactor, these metal oxides get reduced after reacting with fuel gas resulting in the formation of an effluent stream containing CO₂ and H₂O, from which CO₂ can easily be separated by condensing H₂O. In this study, a 2-dimensional computational fluid dynamics (CFD) model for a fuel reactor utilizing coal as the solid fuel and Fe₂O₃ as oxygen carrier is developed and is simulated using ANSYS—Fluent. The model accounts for fluid-particle and particle-particle interactions and fuel and oxygen carrier reaction kinetics as well as devolatilization and the rate limiting char gasification of coal. The performance of the reactor and coal conversion rates are studied and presented in this work.

This work is concerned with the analysis of flow behaviour in a jet ejectors using Computational Fluid Dynamics (CFD) tools. Jet ejectors are the best devices among all compressors and vacuum pumps. The Ejector includes three most important parts namely, nozzle, mixing chamber and diffuser. In the present work designing and meshing of the ejector components are performed in GAMBIT and parts are exported to an evaluation software. The use of the geometrical design parameters obtained via fixing governing equations using the analysis done by FLUENT software to assess the greatest entrainment ratio that would be performed for a given set of operating conditions, in which the entrainment ratio (ER) is the ratio of the mass flow rate of the secondary fluid to the primary fluid. In the present work, we studied the flow behaviour of constant area ejector and constant pressure ejector further analyzed with different motive fluids. Distinct contours and vectors are plotted and their flow behavior on the corresponding jet ejectors are studied. It is also concluded that motive fluid containing larger molecular weight will have an effect on the ejector performance.

Microfluidic devices have great potential in the fields of automation and miniaturization for handling and analysis of fluids. In the present work, study on single-phase flow across orifice in similar shaped microchannel (circular) was carried out under isothermal conditions. CFD Studies were carried out using ANSYS CFX 14.0, varying the fluid velocity ($$ U_{m} $$Um) and orifice contraction ratio ($$ \gamma_{do} = d/D $$γdo=d/D). Pressure drop characteristics of low Reynolds number Newtonian (water) and non-Newtonian (1.5 % CMC solution, human blood with 45 % haemoglobin and human blood with 70 % haemoglobin) fluids across orifice in circular ($$ D $$D = 400 µm) were investigated. Simulations were carried out for predicting the orifice pressure drop characteristics for various values of orifice contraction ratio.