The document presents a theoretical and statistical model for predicting flux in direct contact membrane distillation (DCMD). Theoretical models are applied to predict DCMD performance based on heat and mass transfer analysis. Statistical analysis of variance (ANOVA) is used to determine the effect of operating parameters on performance. A regression model is developed for predicting flux and shows good agreement with experimental data and the theoretical model. Feed temperature, flow rates, and other parameters are considered in both the theoretical and statistical models.
This document summarizes a study on the ablation behavior of carbon/carbon (C/C) composites under different temperature conditions simulated using an arc plasma heater. Three key points:
1) C/C composite samples were tested in oxygen-lean (~4750 K) and oxygen-rich (~2467 K) temperature regimes in the plasma heater to study the effects of sublimation and oxidation on ablation rates. Ablation rate increased with higher oxygen conditions.
2) Back-face temperatures and residual compressive strength were tested on samples exposed to the extreme temperature conditions. The 4750 K sample showed toughening in the affected zone while the 2467 K sample showed lower strength and modulus.
Optimizing pumping rate in pipe networks supplied by groundwater sourcesMedhat Elzahar
This document presents an analytical solution for determining the optimal pumping rate in pipe networks supplied by groundwater wells. The solution is based on maximizing economic benefit from the produced water. It utilizes a case study of a pipe network supplied by two wells connected to an elevated tank and distribution pipes. Cost functions are developed that consider pipe network costs, pumping and pump costs, well and tank costs, and operation and maintenance costs. An optimization technique called the gradient method is applied to these cost functions to derive an analytical solution for optimal pumping rate. The solution is verified against graphical solutions and prior studies on the example pipe network, demonstrating the reliability of the analytical approach.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Analysis for predicting the Input Interactions of HBF Performance at -10 μm P...journal ijrtem
This document summarizes an analysis of factors influencing the performance of a Hyper Baric Filter (HBF) used to treat iron ore fines. Experiments were conducted using a 3^3 full factorial design to examine the effects of vessel pressure, snap blow, and filter disk rotation on moisture reduction and material throughput. Linear regression models were developed for each response and validated. Vessel pressure had the greatest effect on moisture reduction, explaining over 80% of the variation, while vessel pressure, disk rotation, and their interaction most influenced throughput. The models can predict HBF performance within the required level of confidence.
Flux optimization in air gap membrane distillation system for water desalina...Dahiru Lawal
The document summarizes research on optimizing an air gap membrane distillation (AGMD) system for desalination. The researcher conducted experiments to investigate how operating parameters like feed temperature, coolant temperature, feed flow rate, coolant flow rate, and air gap width affect permeate flux. Using Taguchi experimental design, the maximum flux of 76 kg/m2h was achieved at 80°C feed temperature, 20°C coolant temperature, 5 L/min feed flow rate, 2 L/min coolant flow rate, and 3mm air gap width. Regression analysis showed the model could predict experimental flux values within 10%. The researcher concluded temperature differences between feed and coolant most affected flux, while coolant flow
The document discusses different analytical techniques used to analyze drug-excipient interactions, including thermogravimetric analysis (TGA), differential thermal analysis (DTA), differential scanning calorimetry (DSC), X-ray powder diffraction (XRD), and FT-IR spectroscopy. Each technique is described in one to two sentences. TGA measures mass changes as temperature changes and provides information on physical and chemical phenomena like decomposition. DTA and DSC measure the temperature and heat flow differences between a sample and reference to determine endothermic and exothermic reactions like melting. XRD analyzes diffraction patterns to characterize crystal structure and polymorphism. FT-IR identifies functional groups and structures by analyzing absorption peaks.
The Calculation of Optimal Osmotic Dehydration Process Parameters for Mushroo...Agriculture Journal IJOEAR
Abstract— The Firefly Algorithm (FA) is employed to determine the optimal parameter settings in a case study of the osmotic dehydration process of mushrooms. In the case, the functional form of the dehydration model is established through a response surface technique and the resulting mathematical programming is formulated as a non-linear goal programming model. For optimization purposes, a computationally efficient, FA-driven method is used and the resulting optimal process parameters are shown to be superior to those from previous approaches.
This document describes a study on developing hybrid fixed-site-carrier (FSC) membranes for removing CO2 from natural gas. The key points are:
1. Nanotube-reinforced PVAm/PVA membranes were prepared and tested in small pilot modules up to 40 bar, showing high CO2 permeance and selectivity.
2. Membrane performance decreased with increasing pressure due to compaction and carrier saturation. It also depended on CO2 concentration in the feed gas.
3. Process simulation using the experimental data evaluated the techno-economic feasibility of using the membranes for natural gas sweetening. The results showed potential for low-cost CO2 removal from gas with 10% CO
This document summarizes a study on the ablation behavior of carbon/carbon (C/C) composites under different temperature conditions simulated using an arc plasma heater. Three key points:
1) C/C composite samples were tested in oxygen-lean (~4750 K) and oxygen-rich (~2467 K) temperature regimes in the plasma heater to study the effects of sublimation and oxidation on ablation rates. Ablation rate increased with higher oxygen conditions.
2) Back-face temperatures and residual compressive strength were tested on samples exposed to the extreme temperature conditions. The 4750 K sample showed toughening in the affected zone while the 2467 K sample showed lower strength and modulus.
Optimizing pumping rate in pipe networks supplied by groundwater sourcesMedhat Elzahar
This document presents an analytical solution for determining the optimal pumping rate in pipe networks supplied by groundwater wells. The solution is based on maximizing economic benefit from the produced water. It utilizes a case study of a pipe network supplied by two wells connected to an elevated tank and distribution pipes. Cost functions are developed that consider pipe network costs, pumping and pump costs, well and tank costs, and operation and maintenance costs. An optimization technique called the gradient method is applied to these cost functions to derive an analytical solution for optimal pumping rate. The solution is verified against graphical solutions and prior studies on the example pipe network, demonstrating the reliability of the analytical approach.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Analysis for predicting the Input Interactions of HBF Performance at -10 μm P...journal ijrtem
This document summarizes an analysis of factors influencing the performance of a Hyper Baric Filter (HBF) used to treat iron ore fines. Experiments were conducted using a 3^3 full factorial design to examine the effects of vessel pressure, snap blow, and filter disk rotation on moisture reduction and material throughput. Linear regression models were developed for each response and validated. Vessel pressure had the greatest effect on moisture reduction, explaining over 80% of the variation, while vessel pressure, disk rotation, and their interaction most influenced throughput. The models can predict HBF performance within the required level of confidence.
Flux optimization in air gap membrane distillation system for water desalina...Dahiru Lawal
The document summarizes research on optimizing an air gap membrane distillation (AGMD) system for desalination. The researcher conducted experiments to investigate how operating parameters like feed temperature, coolant temperature, feed flow rate, coolant flow rate, and air gap width affect permeate flux. Using Taguchi experimental design, the maximum flux of 76 kg/m2h was achieved at 80°C feed temperature, 20°C coolant temperature, 5 L/min feed flow rate, 2 L/min coolant flow rate, and 3mm air gap width. Regression analysis showed the model could predict experimental flux values within 10%. The researcher concluded temperature differences between feed and coolant most affected flux, while coolant flow
The document discusses different analytical techniques used to analyze drug-excipient interactions, including thermogravimetric analysis (TGA), differential thermal analysis (DTA), differential scanning calorimetry (DSC), X-ray powder diffraction (XRD), and FT-IR spectroscopy. Each technique is described in one to two sentences. TGA measures mass changes as temperature changes and provides information on physical and chemical phenomena like decomposition. DTA and DSC measure the temperature and heat flow differences between a sample and reference to determine endothermic and exothermic reactions like melting. XRD analyzes diffraction patterns to characterize crystal structure and polymorphism. FT-IR identifies functional groups and structures by analyzing absorption peaks.
The Calculation of Optimal Osmotic Dehydration Process Parameters for Mushroo...Agriculture Journal IJOEAR
Abstract— The Firefly Algorithm (FA) is employed to determine the optimal parameter settings in a case study of the osmotic dehydration process of mushrooms. In the case, the functional form of the dehydration model is established through a response surface technique and the resulting mathematical programming is formulated as a non-linear goal programming model. For optimization purposes, a computationally efficient, FA-driven method is used and the resulting optimal process parameters are shown to be superior to those from previous approaches.
This document describes a study on developing hybrid fixed-site-carrier (FSC) membranes for removing CO2 from natural gas. The key points are:
1. Nanotube-reinforced PVAm/PVA membranes were prepared and tested in small pilot modules up to 40 bar, showing high CO2 permeance and selectivity.
2. Membrane performance decreased with increasing pressure due to compaction and carrier saturation. It also depended on CO2 concentration in the feed gas.
3. Process simulation using the experimental data evaluated the techno-economic feasibility of using the membranes for natural gas sweetening. The results showed potential for low-cost CO2 removal from gas with 10% CO
This ppt is about the cold mix asphalt. Some of its advantages and disadvantages over hot mix asphalt. Also some discussion about the test conducted on the cold mix asphalt and the result of it. And also discuss about the conclusion of above.
Higher molecular weight hydroxypropylcellulose (HPC) polymers are less thermally stable and more prone to discoloration at lower temperatures than lower molecular weight HPCs. Thermal gravimetric analysis showed slight discoloration starting around 140°C for the lowest molecular weight grade and around 190°C for the highest grade. Rheological analysis found that all grades can be extruded below 200°C but lower molecular weight grades have melt viscosities under 100,000 Pa·s, making them better suited for hot melt extrusion without plasticization. Extruded samples of all grades still met compendial testing requirements.
This laboratory manual provides instructions and procedures for experiments in a Physical Pharmacy-II Lab course. The manual was prepared by Md. Imran Nur Manik and acknowledges Sushanta Halder. The manual includes 4 experiments focused on topics like the variation of viscosity with temperature, determination of adsorption isotherms, determination of reaction velocity constants, and equilibrium constants. Precise procedures, observations, calculations and results are provided for each experiment.
A novel validated stability Indicating RP-HPLC Method Development for the est...Naveen Chennamaneni
Best reserch paper A novel validated stability Indicating RP-HPLC Method Development for the estimation of Certinib in its bulk and finished Dosage form as per ICH Guidelines
Quality Control Analysis of Natural Gas Condensate Products through Refining Process
Sarker, K., Faruque, M.O. (2017).Quality Control Analysis of Natural Gas Condensate Products through Refining Process.In International Conference on Engineering, Research, Innovation and Education.Shahjalal University of Science and Technology, Sylhet, Bangladesh, January 13-15. Sylhet, Bangladesh: School of Applied Sciences and Technology. 529-534.
Development and Pharmaceutical Evaluation of Clotrimazole Loaded Topical Hydr...Madiha Mushtaque
SUMMARY. The present study addresses the solubility issue of a hydrophobic antifungal drug and its incorporation
into a hydrogel matrix. The prime objective of the study was to develop a preformed hydrogel
of 1% w/w clotrimazole with the introduction of water miscible co-solvents such as glycerin and polyethylene
glycol. Carbomer was used as gelling agent in different concentrations. The stability of the formulations,
their spreadability, pH, drug content, viscosity and in vitro drug release has been assessed while the
optimization has been carried out through Design Expert® ver. 7.0. A spectrophotometric method has
been developed for the analysis of clotrimazole from the developed formulations and it was found to be
within the USP limits. The best drug release was found from F2 formulation that contains 0.5 g carbomer
hence it was considered as optimized formulation. It is conclu
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
This document discusses kinetics and drug stability. It defines chemical kinetics as the study of reaction rates and explains zero-order, first-order, and mixed-order reactions. Factors that affect reaction rates like temperature, light, and solvents are also covered. The document also discusses complex reactions, kinetics of drug decomposition, stability testing strategies, accelerated stability analysis, and shelf life prediction. Finally, it addresses stability considerations for solid dosage forms.
Experimental Study of Material Removal Efficiency in EDM Using Various Types ...IJERD Editor
The machining process in electrical discharge machining (EDM) consists of a melting process and a
removal process. A region of the workpiece surface heated by the discharge plasma is melted and a portion of
the melted region is removed from the workpiece body. The rest of the melted region remains on the workpiece
surface and re-solidified as a white layer. In previous research, to evaluate the removal ability, a ratio of the
removal volume to the melted volume is defined as the material removal efficiency.
In this study, the material removal efficiency was investigated to develop an understanding of the
machining mechanism in EDM. As a result of experiments, it is found that the material removal efficiencies
show almost the same value, whereas the removal volume varies with the type of dielectric oil or the discharge
duration. To advance the study about the machining mechanism in EDM, the simulation for the workpiece
temperature distribution, considering the effect of the type of dielectric oil or the discharge duration, should be
conducted further
Delignification of pulp with two ternary deep eutectic solvents: Urea-acetami...Michal Jablonsky
Using deep eutectic solvents (DESs), which ones act as solvent systems, offer an interesting green alternative to conventional technology in materials science, especially in the biomass processing. There is lack of information dealing with the delignification and bleaching effect of DESs in broad-leaved fiber process. This work describes application of various DESs on unbleached pulp, to study the influence of dissolution of lignin and protection of cellulose in the delignification process. In this work, two ternary deep eutectic solvents (urea-acetamide-glycerol) in molar ratio 1 : 2 : 3 and (malic acid-proline-lactic acid) in molar ratio 1 : 2 : 4 were synthesized and their density was studied in a temperature range of 25 to 75 0 C. Unbleached pulp (Kappa 14) was treated with prepared ternary deep eutectic solvents. The treatment was carried out in a water bath at present temperature of 60 0 C and atmospheric pressure for 2 hours. Solubility tests of cellulose were performed using pure cellulose (Whatman paper) in the DESs reagents. In 50 mL glass bottles, 0.5 g of the respective component was added separately into 20 mL of DES reagent and then incubated at 60 0 C for 2 h. The samples were filtered through glass fiber filters and dried at 105 0 C to constant weight. The weight of dried residual solid components was calculated in order to evaluate the % solubility in the DES reagent. Density of urea-acetamide-glycerol (molar ratio 1 : 2 : 3) decreased with a temperature from 1,220 to 1,199 g/cm 3 and density of malic acid-proline-lactic acid (molar ratio 1 : 2 : 4) decreased from 1,292 to 1,220 g/cm 3. Application of DESs to the lignocellulosic matrix pulp does not resulted in a significant decrease of lignin content. Deep eutectic solvent (urea-acet-amide-glycerol) in molar ratio 1 : 2 : 3 removed 5,4 % and DES (malic acid-proline-lactic acid) in molar ratio 1 : 2 : 4 removed 1.4 % lignin from unbleached pulp. The solubility of cellulose in ternary deep eutectic solvents was zero. Results show that prepared ternary deep eutectic solvents are able to delignify the pulp. However, the efficiency of delignification is not comparable to that of oxygen delignification. At the same time, used deep eutectic solvents do not cause dissolution of cellulose in pulp fibers.
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
The papers for publication in The International Journal of Engineering& Science are selected through rigorous peer reviews to ensure originality, timeliness, relevance, and readability.
Establishing Optimal Dehydration Process Parameters for Papaya By EmployingA ...IJERA Editor
This study employs a Firefly Algorithm (FA) to determine the optimal osmotic dehydration parameters for papaya. The functional form of the osmotic dehydration model is established via a standard response surface technique. The format of the resulting optimization model to be solved is a non-linear goal programming problem. While various alternate solution approaches are possible, an FA-driven procedure is employed. For optimization purposes, it has been demonstrated that the FA is more computationally efficient than other such commonly-used metaheuristics as genetic algorithms, simulated annealing, and enhanced particle swarm optimization. Hence, the FA approach is a very computationally efficient procedure. It can be shown that the resulting solution determined for the osmotic process parameters is superior to those from all previous approaches.
This study examines the heat transfer properties of submicro-encapsulated phase change material (PCM) plates for potential use in food packaging applications. Rubitherm RT5 PCM was encapsulated in polycaprolactone shells using electrospinning. Plates with 30% and 38% PCM mass fractions were tested experimentally and modeled numerically using an enthalpy method. Experimental differential scanning calorimetry showed the 38% plate had a higher phase change enthalpy. Numerical modeling validated by experiments demonstrated the encapsulated PCM plates provide better thermal buffering than standard cardboard packaging.
This document describes a method for reinforcing Nylon 6 filaments with multi-walled carbon nanotubes (MWCNTs) through an extrusion process. MWCNTs and Nylon 6 powder were dry mixed at 1 wt.% loading and extruded into continuous filaments. Tests found the MWCNT filaments had a 220% increase in Young's modulus and 164% increase in strength compared to neat Nylon filaments due to alignment of the MWCNTs and strong interfacial bonding between the nanotubes and polymer matrix during extrusion and drawing. Thermal and structural analysis showed the MWCNTs increased the glass transition temperature slightly but did not change the melting temperature or crystallinity of the
This document discusses the thermal and rheological properties of Povidone (PVP) and Copovidone polymers for use in hot melt extrusion. It finds that all PVP polymers show some degradation above 180°C, so that temperature is recommended as the upper limit for melt extrusion. PVP K-12 and S-630 are found to have ideal rheological properties for melt extrusion, with melt viscosities between 700-100,000 Pa.s. The other grades may require plasticization to be successfully melt extruded below 180°C.
Presentation on-stability-study of pharmaceutical productMd Mohsin
this content takes important information about stability & stability study of pharmaceutical products including guidelines,climate zone,testing conditions,sampling plan,extension of shelf life,re test,current trends in stability study etc.
Kinetics of Stability & Stability Testing Sidharth Mehta
This document discusses kinetics of stability and stability testing. It defines drug kinetics as how a drug changes over time and explains zero and first order reaction kinetics. Factors affecting reaction rate and types of drug degradation are covered. Stability testing is defined and its importance, types, methods, guidelines and climatic zones are summarized. Methods for estimating shelf life and determining expiration dates are also presented.
The document describes using design of experiments (DoE) techniques to optimize the rosin extraction process from cannabis. DoE was used to study how temperature, pressure, time, and actuation speed affect yield and quality. Temperature had the largest influence, with higher temperatures increasing yield but decreasing quality. The optimal conditions found balanced high yield with high quality. DoE allowed for an efficient process to produce rosin at scale with minimal waste and consistent, high-quality product.
Design and Construction of a Simple and Reliable Temperature Control Viscomet...theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
Simulation of curing process of carbon/epoxy composite during autoclave degas...Darkdragon766
Simulation of curing process of carbon/epoxy composite during
autoclave degassing molding by considering phase changes of epoxy
resin
Seong-Hwan Yoo a, b
, Min-Gu Han a
, Jin-Ho Hong a
, Seung-Hwan Chang a, *
a School of Mechanical Engineering, Chung-Ang University (CAU), 221, Huksuk-Dong, Dongjak-Gu, Seoul 156-756, Republic of Korea
b Korea Photonics Technology Institute Lighting Solution R&BD Center, Gwangju, Republic of Korea
Group4.plasma surface modification of polylactic acid to promoteRoy Rodriguez Solano
Plasma surface modification of polylactic acid (PLA) films was investigated using a dielectric barrier discharge (DBD) operating at medium pressure in different atmospheres. After plasma treatment, water contact angle measurements showed increased hydrophilicity of the PLA surface. X-ray photoelectron spectroscopy revealed an increased oxygen content on treated surfaces. Cell culture tests found that plasma treatment improved initial fibroblast cell attachment and morphology compared to untreated PLA, though no difference in proliferation was observed after 7 days. Plasma treatment in air was determined to be the most economical option for modifying PLA surfaces to enhance cell interactions.
Thin Film Pressure Estimation of Argon and Water using LAMMPSCSCJournals
In this work, we investigate the pressure and density characteristics of water film when simulated using the emerging technique called many body dissipative particle dynamics method. This work also layout the methodology of estimating local pressure from LAMMPS simulation using Harasima scheme. Using the triangular shaped cloud interpolation function, pressure and density are estimated at local bins and compared with the experimental database. Our results show good agreement for the molecular dynamics results of the argon system, while the many body dissipative particle model fails to simulate the water properties at room temperature. In its current form, the many body dissipative particle method cannot be used for accurate liquid vapor interfacial simulations and heat transfer studies.
This ppt is about the cold mix asphalt. Some of its advantages and disadvantages over hot mix asphalt. Also some discussion about the test conducted on the cold mix asphalt and the result of it. And also discuss about the conclusion of above.
Higher molecular weight hydroxypropylcellulose (HPC) polymers are less thermally stable and more prone to discoloration at lower temperatures than lower molecular weight HPCs. Thermal gravimetric analysis showed slight discoloration starting around 140°C for the lowest molecular weight grade and around 190°C for the highest grade. Rheological analysis found that all grades can be extruded below 200°C but lower molecular weight grades have melt viscosities under 100,000 Pa·s, making them better suited for hot melt extrusion without plasticization. Extruded samples of all grades still met compendial testing requirements.
This laboratory manual provides instructions and procedures for experiments in a Physical Pharmacy-II Lab course. The manual was prepared by Md. Imran Nur Manik and acknowledges Sushanta Halder. The manual includes 4 experiments focused on topics like the variation of viscosity with temperature, determination of adsorption isotherms, determination of reaction velocity constants, and equilibrium constants. Precise procedures, observations, calculations and results are provided for each experiment.
A novel validated stability Indicating RP-HPLC Method Development for the est...Naveen Chennamaneni
Best reserch paper A novel validated stability Indicating RP-HPLC Method Development for the estimation of Certinib in its bulk and finished Dosage form as per ICH Guidelines
Quality Control Analysis of Natural Gas Condensate Products through Refining Process
Sarker, K., Faruque, M.O. (2017).Quality Control Analysis of Natural Gas Condensate Products through Refining Process.In International Conference on Engineering, Research, Innovation and Education.Shahjalal University of Science and Technology, Sylhet, Bangladesh, January 13-15. Sylhet, Bangladesh: School of Applied Sciences and Technology. 529-534.
Development and Pharmaceutical Evaluation of Clotrimazole Loaded Topical Hydr...Madiha Mushtaque
SUMMARY. The present study addresses the solubility issue of a hydrophobic antifungal drug and its incorporation
into a hydrogel matrix. The prime objective of the study was to develop a preformed hydrogel
of 1% w/w clotrimazole with the introduction of water miscible co-solvents such as glycerin and polyethylene
glycol. Carbomer was used as gelling agent in different concentrations. The stability of the formulations,
their spreadability, pH, drug content, viscosity and in vitro drug release has been assessed while the
optimization has been carried out through Design Expert® ver. 7.0. A spectrophotometric method has
been developed for the analysis of clotrimazole from the developed formulations and it was found to be
within the USP limits. The best drug release was found from F2 formulation that contains 0.5 g carbomer
hence it was considered as optimized formulation. It is conclu
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
This document discusses kinetics and drug stability. It defines chemical kinetics as the study of reaction rates and explains zero-order, first-order, and mixed-order reactions. Factors that affect reaction rates like temperature, light, and solvents are also covered. The document also discusses complex reactions, kinetics of drug decomposition, stability testing strategies, accelerated stability analysis, and shelf life prediction. Finally, it addresses stability considerations for solid dosage forms.
Experimental Study of Material Removal Efficiency in EDM Using Various Types ...IJERD Editor
The machining process in electrical discharge machining (EDM) consists of a melting process and a
removal process. A region of the workpiece surface heated by the discharge plasma is melted and a portion of
the melted region is removed from the workpiece body. The rest of the melted region remains on the workpiece
surface and re-solidified as a white layer. In previous research, to evaluate the removal ability, a ratio of the
removal volume to the melted volume is defined as the material removal efficiency.
In this study, the material removal efficiency was investigated to develop an understanding of the
machining mechanism in EDM. As a result of experiments, it is found that the material removal efficiencies
show almost the same value, whereas the removal volume varies with the type of dielectric oil or the discharge
duration. To advance the study about the machining mechanism in EDM, the simulation for the workpiece
temperature distribution, considering the effect of the type of dielectric oil or the discharge duration, should be
conducted further
Delignification of pulp with two ternary deep eutectic solvents: Urea-acetami...Michal Jablonsky
Using deep eutectic solvents (DESs), which ones act as solvent systems, offer an interesting green alternative to conventional technology in materials science, especially in the biomass processing. There is lack of information dealing with the delignification and bleaching effect of DESs in broad-leaved fiber process. This work describes application of various DESs on unbleached pulp, to study the influence of dissolution of lignin and protection of cellulose in the delignification process. In this work, two ternary deep eutectic solvents (urea-acetamide-glycerol) in molar ratio 1 : 2 : 3 and (malic acid-proline-lactic acid) in molar ratio 1 : 2 : 4 were synthesized and their density was studied in a temperature range of 25 to 75 0 C. Unbleached pulp (Kappa 14) was treated with prepared ternary deep eutectic solvents. The treatment was carried out in a water bath at present temperature of 60 0 C and atmospheric pressure for 2 hours. Solubility tests of cellulose were performed using pure cellulose (Whatman paper) in the DESs reagents. In 50 mL glass bottles, 0.5 g of the respective component was added separately into 20 mL of DES reagent and then incubated at 60 0 C for 2 h. The samples were filtered through glass fiber filters and dried at 105 0 C to constant weight. The weight of dried residual solid components was calculated in order to evaluate the % solubility in the DES reagent. Density of urea-acetamide-glycerol (molar ratio 1 : 2 : 3) decreased with a temperature from 1,220 to 1,199 g/cm 3 and density of malic acid-proline-lactic acid (molar ratio 1 : 2 : 4) decreased from 1,292 to 1,220 g/cm 3. Application of DESs to the lignocellulosic matrix pulp does not resulted in a significant decrease of lignin content. Deep eutectic solvent (urea-acet-amide-glycerol) in molar ratio 1 : 2 : 3 removed 5,4 % and DES (malic acid-proline-lactic acid) in molar ratio 1 : 2 : 4 removed 1.4 % lignin from unbleached pulp. The solubility of cellulose in ternary deep eutectic solvents was zero. Results show that prepared ternary deep eutectic solvents are able to delignify the pulp. However, the efficiency of delignification is not comparable to that of oxygen delignification. At the same time, used deep eutectic solvents do not cause dissolution of cellulose in pulp fibers.
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
The papers for publication in The International Journal of Engineering& Science are selected through rigorous peer reviews to ensure originality, timeliness, relevance, and readability.
Establishing Optimal Dehydration Process Parameters for Papaya By EmployingA ...IJERA Editor
This study employs a Firefly Algorithm (FA) to determine the optimal osmotic dehydration parameters for papaya. The functional form of the osmotic dehydration model is established via a standard response surface technique. The format of the resulting optimization model to be solved is a non-linear goal programming problem. While various alternate solution approaches are possible, an FA-driven procedure is employed. For optimization purposes, it has been demonstrated that the FA is more computationally efficient than other such commonly-used metaheuristics as genetic algorithms, simulated annealing, and enhanced particle swarm optimization. Hence, the FA approach is a very computationally efficient procedure. It can be shown that the resulting solution determined for the osmotic process parameters is superior to those from all previous approaches.
This study examines the heat transfer properties of submicro-encapsulated phase change material (PCM) plates for potential use in food packaging applications. Rubitherm RT5 PCM was encapsulated in polycaprolactone shells using electrospinning. Plates with 30% and 38% PCM mass fractions were tested experimentally and modeled numerically using an enthalpy method. Experimental differential scanning calorimetry showed the 38% plate had a higher phase change enthalpy. Numerical modeling validated by experiments demonstrated the encapsulated PCM plates provide better thermal buffering than standard cardboard packaging.
This document describes a method for reinforcing Nylon 6 filaments with multi-walled carbon nanotubes (MWCNTs) through an extrusion process. MWCNTs and Nylon 6 powder were dry mixed at 1 wt.% loading and extruded into continuous filaments. Tests found the MWCNT filaments had a 220% increase in Young's modulus and 164% increase in strength compared to neat Nylon filaments due to alignment of the MWCNTs and strong interfacial bonding between the nanotubes and polymer matrix during extrusion and drawing. Thermal and structural analysis showed the MWCNTs increased the glass transition temperature slightly but did not change the melting temperature or crystallinity of the
This document discusses the thermal and rheological properties of Povidone (PVP) and Copovidone polymers for use in hot melt extrusion. It finds that all PVP polymers show some degradation above 180°C, so that temperature is recommended as the upper limit for melt extrusion. PVP K-12 and S-630 are found to have ideal rheological properties for melt extrusion, with melt viscosities between 700-100,000 Pa.s. The other grades may require plasticization to be successfully melt extruded below 180°C.
Presentation on-stability-study of pharmaceutical productMd Mohsin
this content takes important information about stability & stability study of pharmaceutical products including guidelines,climate zone,testing conditions,sampling plan,extension of shelf life,re test,current trends in stability study etc.
Kinetics of Stability & Stability Testing Sidharth Mehta
This document discusses kinetics of stability and stability testing. It defines drug kinetics as how a drug changes over time and explains zero and first order reaction kinetics. Factors affecting reaction rate and types of drug degradation are covered. Stability testing is defined and its importance, types, methods, guidelines and climatic zones are summarized. Methods for estimating shelf life and determining expiration dates are also presented.
The document describes using design of experiments (DoE) techniques to optimize the rosin extraction process from cannabis. DoE was used to study how temperature, pressure, time, and actuation speed affect yield and quality. Temperature had the largest influence, with higher temperatures increasing yield but decreasing quality. The optimal conditions found balanced high yield with high quality. DoE allowed for an efficient process to produce rosin at scale with minimal waste and consistent, high-quality product.
Design and Construction of a Simple and Reliable Temperature Control Viscomet...theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
Simulation of curing process of carbon/epoxy composite during autoclave degas...Darkdragon766
Simulation of curing process of carbon/epoxy composite during
autoclave degassing molding by considering phase changes of epoxy
resin
Seong-Hwan Yoo a, b
, Min-Gu Han a
, Jin-Ho Hong a
, Seung-Hwan Chang a, *
a School of Mechanical Engineering, Chung-Ang University (CAU), 221, Huksuk-Dong, Dongjak-Gu, Seoul 156-756, Republic of Korea
b Korea Photonics Technology Institute Lighting Solution R&BD Center, Gwangju, Republic of Korea
Group4.plasma surface modification of polylactic acid to promoteRoy Rodriguez Solano
Plasma surface modification of polylactic acid (PLA) films was investigated using a dielectric barrier discharge (DBD) operating at medium pressure in different atmospheres. After plasma treatment, water contact angle measurements showed increased hydrophilicity of the PLA surface. X-ray photoelectron spectroscopy revealed an increased oxygen content on treated surfaces. Cell culture tests found that plasma treatment improved initial fibroblast cell attachment and morphology compared to untreated PLA, though no difference in proliferation was observed after 7 days. Plasma treatment in air was determined to be the most economical option for modifying PLA surfaces to enhance cell interactions.
Thin Film Pressure Estimation of Argon and Water using LAMMPSCSCJournals
In this work, we investigate the pressure and density characteristics of water film when simulated using the emerging technique called many body dissipative particle dynamics method. This work also layout the methodology of estimating local pressure from LAMMPS simulation using Harasima scheme. Using the triangular shaped cloud interpolation function, pressure and density are estimated at local bins and compared with the experimental database. Our results show good agreement for the molecular dynamics results of the argon system, while the many body dissipative particle model fails to simulate the water properties at room temperature. In its current form, the many body dissipative particle method cannot be used for accurate liquid vapor interfacial simulations and heat transfer studies.
This document describes the simulation and design of a process to recover monoethylene glycol (MEG) from effluent waste streams of a petrochemical company in Iran. Aspen Plus simulation software was used to model the process, which involves separating water, salts, and various glycols (MEG, DEG, TEG, TTEG) using a series of distillation columns. Sensitivity analyses were performed to optimize column parameters such as pressure, reflux ratio, and boilup ratio. The results showed that MEG, DEG, TEG, and TTEG could be recovered at rates of 5.01, 2.039, 0.062, and 0.089 kg/hr, respectively.
Enhancement of heat transfer rate using MgO nanofluid in heat exchangerIRJET Journal
This document summarizes research on enhancing heat transfer in heat exchangers using magnesium oxide (MgO) nanofluids. The authors conducted experiments using a shell and tube heat exchanger with MgO nanofluids at concentrations of 0.1%, 0.3%, and 0.5% added to a mixture of water and propylene glycol as the base fluid. Their results showed that adding MgO nanoparticles increased the thermal conductivity and overall heat transfer coefficient of the base fluid. The maximum enhancement of 33.51% in overall heat transfer coefficient occurred at a nanofluid concentration of 0.5% and flow rates of 6 and 12 liters/min compared to the base fluid alone. The maximum enhancement of 37.71
Optimizing the Reverse Osmosis Process Parameters by Maximizing Recovery by T...QUESTJOURNAL
ABSTRACT: In this study, the effects of Operating Pressure, Potential Hydrogen, Oxidation Reduction Potential and Anti Scaling Agent on multi responses like Permeate, COD, Total Solids, Conductivity and Hardness in the Reverse Osmosis Process were experimentally investigated on RO 8100 ST8 PT44 400Wl machine. The settings of RO parameters were determined by using Taguchi’s experimental design method. Orthogonal arrays of Taguchi, the signal-to-noise (S/N) ratio, the analysis of variance (ANOVA) are employed to find the optimal levels and to analyze the effect of the RO parameters. Results show that potential of hydrogen, operating pressure, oxidation reduction potential and anti scaling agent are the four Parameters that influence the Permit more effectively and COD, Total Solids, Conductivity and Hardness respectively. Improvement in recovery of RO process is achieved with optimize setting. Finally, the ranges for best RO conditions are proposed for ZLD process.
Computational analysis for different characteristics of the circular microcha...IRJET Journal
This document summarizes research on computational analysis of flow characteristics in circular microchannels under low Reynolds number conditions. It discusses how a variable diameter design can improve flow rate and heat dissipation from electronic chips. The document reviews several past studies on microchannel flow and heat transfer. It is found that increasing the microchannel diameter increases heat dissipation rate, with a proposed design improving flow rate and heat removal for chip cooling.
Implementation of the characteristic equation method in quasi-dynamic.pdfAlvaro Ochoa
This document presents a mathematical model for simulating the quasi-dynamic behavior of an absorption chiller that uses a lithium nitrate/ammonia working fluid pair. The model is based on the characteristic equation method and solves mass and energy balance equations using the first law of thermodynamics. It models the major system components as single thermal components that exchange heat between external water circuits and internal refrigerant/solution circuits. Validation against experimental data showed good agreement, with relative errors below 5%. A sensitivity analysis then examined the chiller's dynamic response to variations in operating temperatures.
Enhancing Heat Transfer Efficiency: Nanofluid Integration in Diverse Systems ...IRJET Journal
This document discusses research on enhancing heat transfer efficiency through the integration of nanofluids in various systems and coiled heat exchangers. It investigates the effects of nanofluids on cooling towers, car radiators, refrigeration systems, and shell and helical coiled tube heat exchangers. The study models a double helix coiled tube heat exchanger using computational fluid dynamics and compares its performance when water and nanofluids are used. Nanofluids with 0.75% volume fraction and added surfactants for stability are tested. The results are analyzed based on heat transfer rate, effectiveness, and other thermal properties to evaluate the potential advantages of using hybrid nanofluids in coiled heat exchangers
Exergo-economic analysis of a seawater reverse osmosis plant with various ret...ahmad598
This document analyzes the performance and product costs of a seawater reverse osmosis desalination plant with four retrofit options using pressure exchangers instead of conventional energy recovery turbines. The analysis finds that introducing a pressure exchanger can reduce energy consumption by around 24% and increase second-law efficiency. It also shows that including post-treatment and distribution sections increases the product cost by approximately 20%. Of the retrofit options, using a booster pump with a pressure exchanger is determined to have the lowest product water cost while also enhancing plant capacity.
This document outlines an experimental study on air gap membrane distillation desalination. The objectives were to design and test a lab-scale AGMD system, investigate the effect of operating parameters on distillate production, develop a theoretical model, and optimize system performance. Key results included that flux increased with higher feed temperature but decreased with higher coolant temperature. The theoretical model showed good agreement with experimental results. System optimization using Taguchi methods aimed to maximize flux. A double-stage module design further increased distillate production.
The document analyzes theoretical models for predicting two-phase frictional pressure drop during condensation in mini channels. Experimental data from 454 tests with hydraulic diameters of 0.952-1.152 mm and refrigerants R290, R1234yf, R1234ze, R22, R32, R410A, R134a and R152a is compared to eight pressure drop models. The Kim and Mudawar (2019) model best predicts the experimental data with a mean relative deviation of -7.36% and mean absolute relative deviation of 12.21%. A new modified correlation is developed that improves on the Kim and Mudawar model with a mean relative deviation of 0.000165%
Evaporation effects on jetting performanceRobert Cornell
This document discusses evaporation effects on inkjet performance and image quality. It summarizes that as nozzles sit idle, water evaporation causes large localized viscosity variations in the inkjet ejector. This has a negative impact on jetting performance and print quality. The document then goes into detail explaining the multi-physics involved, including heat and mass convection/diffusion at the ink-air interface, and how this affects the transient viscosity fields and ultimately jetting and image quality. Models are used to predict and understand these relationships and tradeoffs between ink formulation, environmental effects, and ejector design.
This document analyzes the performance of a transcritical refrigeration cycle (TRC) enhanced with a dedicated mechanical subcooling system. Three refrigerants are considered: CO2, N2O, and ethane. Results show that while N2O has the highest COP and exergy performance, CO2 has the best economic performance. Adding a subcooler improves the system COP by 30.74% for CO2, 26.48% for N2O, and 36.1% for ethane, while increasing the unit product cost by 9.04%, 8.37%, and 10.63%, respectively. The subcooling is deemed an effective and economical way to improve refrigeration system performance.
Experimental investigation of cooling performance of an Automobile radiator u...IJERD Editor
This document summarizes an experimental study that investigated the cooling performance of an automobile radiator using an Al2O3-water+ethylene glycol nanofluid. Different volume fractions of Al2O3 nanoparticles between 0.01-0.08% were added to the base fluid and tested. The maximum heat transfer performance observed was a 48% increase over water for the 0.08% volume fraction nanofluid. Flow rates were also varied between 3-15 liters per minute, showing increased heat transfer with higher flow. The nanofluid had increased thermal conductivity compared to the base fluid, improving the radiator's cooling capacity.
The document describes a novel water treatment process combining forward osmosis (FO) and direct contact membrane distillation (DCMD) to produce potable water from wastewater. FO uses a semipermeable membrane to extract fresh water from wastewater into a saline draw solution. DCMD then uses a hydrophobic membrane to vaporize the fresh water from the heated draw solution, producing distilled water. Experiments on a bench-scale system showed water fluxes in FO and DCMD behaved similarly under varying temperature and concentration conditions. Specific reverse salt flux, or draw solution concentration, was influenced by temperature. Maintaining a constant heater operation provided stable FO and DCMD water fluxes better than varying temperature controls.
Experimental Study and CFD Analysis of Thermal Performance Improvement of Car...IRJET Journal
This document summarizes an experimental study and CFD analysis of using MgO/water nanofluid to improve the thermal performance of a car radiator. Experiments were conducted to test different volume fractions of MgO/water nanofluid and measure its thermal properties and heat transfer rate in the radiator. CFD simulations were also performed to validate the experimental temperature distributions. The results showed that using MgO/water nanofluid as the coolant led to higher heat transfer rates and outlet temperatures in the radiator compared to using just water, with enhancements of up to 70% observed, and the performance increased with higher nanoparticle volume fractions.
This document describes an investigation of radial heat transfer in a fixed-bed reactor using both computational fluid dynamics (CFD) simulations and experimental profile measurements. The study aims to validate CFD simulations of heat transfer for both spherical and non-spherical packings against high-resolution temperature profile measurements in a pilot-scale fixed-bed reactor. Experimental temperature profiles were obtained using a thermocouple mounted on a motorized linear axis, allowing sub-millimeter resolution profiles. CFD simulations were set up using discrete element method-generated random packings of glass spheres and ceramic rings. Simulation results were compared to experimental profiles to validate the simulation approach.
Numerical Investigation of Air Cooled Condensers using Different Refrigerantsijtsrd
Condensers are an integral part of refrigeration system. The current research reviews existing work conducted on improving the design and performance of condenser by varying design and operating conditions. The comparative studies between different types of condensers on the basis of COP coefficient of performance , energy consumption, refrigeration capacity are also presented. The effect of operational parameters and other factors along with development of empirical correlation on performance is also presented. Raghvendra Thakur | Ashwini Bhoi "Numerical Investigation of Air Cooled Condensers using Different Refrigerants" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-6 | Issue-2 , February 2022, URL: https://www.ijtsrd.com/papers/ijtsrd49161.pdf Paper URL: https://www.ijtsrd.com/engineering/mechanical-engineering/49161/numerical-investigation-of-air-cooled-condensers-using-different-refrigerants/raghvendra-thakur
This document is a report on membrane or osmotic distillation submitted by a group of 5 chemical engineering students at Gujarat Technological University. It provides an introduction to membrane separation processes and membrane distillation. It discusses the process fundamentals, configurations including direct contact membrane distillation, air gap membrane distillation, sweeping gas membrane distillation and vacuum membrane distillation. It also discusses osmotic distillation and the characteristics of membranes used, including materials, pore size, porosity, tortuosity and thickness. Finally, it summarizes various commercial membranes that have been used for membrane distillation.
Buckingham PI Dimensional Analysis of Cake Yield from Sludge Filtration ProcessAJSERJournal
Buckingham Pi dimensional analysis was used to derive an equation expressing filterability in terms of Filter
cake yield. The model shows that the cake yield from a pressure filter is directly proportional to the filter area of the
vessel, applied pressure and initial solids content of the sludge while being inversely proportional to specific resistance,
viscosity of filtrate, compressibility coefficient of the slurry and pressing time. The new model which incorporated the
compressibility attribute of the slurry hitherto unaccounted for in previous models enables performance of a pressure
filter (Filter Press) to be predicted from a simple laboratory determination of cake yields. It was observed that
increasing ferric chloride dosage from 11.87% to 22.61% increased filter cake yield from 3.785 x 10-4g/cm2
s to 4.4118 x
10-4g/cm2
s while reducing specific resistance from 1.7372 x 1010cm/g to 1.5940 x 1010cm/g. Moreover, the optimum
dosage from the graph to attain acceptable filtrate quality was 19.63% for an operating pressure of 6628.18g/cm2
. It
was also observed that increasing compressibility from 0.7076 cm s2
/g to 0.7314 cm s2
/g led to decreased solids
capture from 3.7682 g/cm2
s to 3.5763 g/cm2
s for the tested 0.0194 g/cm3
sludge sample. Considering the differences in
the parameters tested, the comparative analytical results showed that there was closer agreement between the actual
cake yield and predicted values while values predicted from other models were out of range. Experimental verification
of the new model showed that the predicted performance agrees with the actual experimental values with a correlation
coefficient of 0.993.
Buckingham PI Dimensional Analysis of Cake Yield from Sludge Filtration Process
T4805124135
1. Dahiru U. Lawal Int. Journal of Engineering Research and Applications www.ijera.com
ISSN : 2248-9622, Vol. 4, Issue 8( Version 5), August 2014, pp.124-135
www.ijera.com 124|P a g e
Theoretical and Statistical Models for Predicting Flux in Direct Contact Membrane Distillation Dahiru U. Lawal, Atia E. Khalifa King Fahd University of Petroleum & MineralsDepartment of Mechanical EngineeringDhahran 31261 Saudi Arabia ABSTRACT Theoretical modelhas been applied to predict the performance of Direct Contact Membrane Distillation (DCMD) based on the analysis of heat and mass transfer through the membrane. The performance of DCMD on the account of different operating parameters had been predicted. Feed inlet temperature, coolant inlet temperature, feed flow rate and coolant flow rate are the considered performance variables. Based on the data obtained from theoretical model, statistical analysis of variance (ANOVA) was then performed to determine the significant effect of each operating factors on the DCMD system performance. A new regression model was subsequently developed for predicting the performance of the DCMD system. Resultsrevealed that both theoretical and regression models were in good agreement with each other and also with the selected experimental data used for validation. The maximum percentage error between the two models was found to be1.098%. Hence, the developed regression model is adequate for predict the performance of DCMD system within the domain of the considered analysis. Keywords– Water Desalination, Direct contact membrane distillation, theoretical modelling, ANOVA, Taguchi methodology, regression model.
I. Introduction Membrane distillation (MD) is a thermally driven separation process in which separation is achieved as a result of phase change. MD process is atechnique for separating water vapour from a liquid saline aqueous solution by transport through the poresof hydrophobic membranes, where the driving force is thevapour pressure difference created by temperature differenceacross the membrane. MD has been applied to the separation of volatile compounds from aqueous mixtures, continuousremoval of alcohol produced by fermentation, breaking of azeotropic mixtures, and concentrating various acids.Findley was the first to relate the separation techniques now known as membrane distillation [1]. MD differs from other membrane technology in that the driving force for desalination is due to the vapour pressure difference, rather than the total pressure of water across the membrane. The four basic configurations mainly utilized in MD are the vacuum membrane distillation (VMD), direct contact membrane distillation (DCMD), sweeping gas membrane distillation (SGMD) and air gap membrane distillation (AGMD). In all these MD configuration, membrane coefficient (permeability) limit the performance of MD system.
In DCMD configuration, the temperature difference between the sides of a hydrophobic membrane material creates partial pressure difference which incites water molecule evaporated at the hot feed side to permeate the pores of the membrane. The vaporized water thencondensed in the flowing coolant solution. Theoretical models had been developed and proposed by several researchers. L. Martinez and F.J. Florido Diaz [2] developed a model which is based on a dusty gas model of gas transport through porous media. A direct contact membrane distillation experiment was conducted using two flat sheet membrane material. Two experiment were carried out, in the first experiment, GVHP22 membrane was used while HVHP45 membrane material was employed in the second experiment. The output resultsshow that the developed model prediction were in good agreement with the experimental results. Jian-Mei Li et al [3]investigated experimentally in direct contact membrane distillation (DCMDand vacuum membrane distillation (VMD)), the influence of feed flow and feed temperature on permeate flux using an aqueous solution of 35g/l NaCl. Resultsrevealed that for both DCMD and VMD, Polyethylene (PE) membrane material produces higher water flux in comparison to polypropylene (PP) membrane material.
Robert W Field et al [4] developed a model for overall mass transfer coefficient in direct contact membrane distillation. In the model developed, the membrane effective thickness is consider as the sum of the actual thickness. Resultsshowed that the sum of the additional terms exceeds 100 μm, which implies that the flux is not inversely proportional to
RESEARCH ARTICLE OPEN ACCESS
2. Dahiru U. Lawal Int. Journal of Engineering Research and Applications www.ijera.com
ISSN : 2248-9622, Vol. 4, Issue 8( Version 5), August 2014, pp.124-135
www.ijera.com 125|P a g e
membrane thickness. The study also revealed that the thermal efficiency does not depend on membrane thickness. In conclusion, the investigation revealed that the traditional methodof combining Knudsen and themolecular diffusion coefficient overestimated the resistance. This leads to underestimation of flux.
Tzahi Y. Cath et al [5]experimentally investigate a new DCMD membrane module. In a turbulent flow regime and with a feed water temperature of only 40 oC, the performances of three hydrophobic micro porous membranes were evaluated. Result revealed that reduction in temperature polarization and permeability obstructions could be obtained simultaneously by careful design of a membrane module and configuration of the MD system. It was shown that the permeate flux obtained for the new approach is more than twice of the traditional mode of DCMD when operating at relatively low temperatures. Both NaCl and synthetic sea feed solutions were used in investigation. Economic aspects of the improved DCMD process was discussed and the new enhanced DCMD process was compared with the reverse osmosis (RO) process for desalination. Design of Experiments (DOE) is a powerful statistical tool for process design and products formulation. It can be used to either quantitatively identify the right input parameter to produce a high quality product or enhance process performance. DOE has been successfully applied in the parametric study of AGMD. Khayet and Cojoucaru[6] modelled and optimized air gap membrane distillation system using response surface methodology. The specific performance index and performance index were predicted using developed regression model with the effect of energy consumption as function of different operating variables. Statistical analysis was performed using analysis of variance (ANOVA) to determine the significant level of each parameters. Using Monte Carlo simulation, an optimum variable combination for performance index were found to be 71°C feed inlet temperature, 13.9°C cooling inlet temperature and 183L/h feed flow rate. These variables combination gave an experimental permeate flux of 47.189 kg/m2h. The optimum variables combination for specific performance index were found to be 59°C feed inlet temperature, 13.9°C cooling inlet temperature and 205 L/h feed flow rate which resulted to an experimental output of 188.7kg/kWh.
The objective of this study is to compare the performance of mathematical model with that of developed statistical model inmodelling DCMD system.The modelling results will be validated against the experimental data available. In statistical analysis, both the Taguchi methodology and regression analysis will be exploit to ascertain the influence of DCMD operating parameters. Feed temperature, feed flow rate, coolant temperature, and coolant flow rate are the considered factors.
1.1 Taguchi Techniques
Taguchi method is a structured and robust design approach for determining best combination of factors to yield product. It is used to investigate how different parameters affect the mean and variance of a system performance. The most important stage in design of experiment lies in the selection of control factors. So, many factors are included at the initial stage, while non-significant factors are identified and eliminated at this earlier stage of experimental design [7]. The DOE using Taguchi technique can economically satisfy theneeds of problem solving and system design optimization, as it allows fewer experimental runs usually leading to significant reduction in time and resources requirement for experimentation. While Traditional Design of Experiments focuses on how different design factors affect mean results, Taguchi’s DOE put emphasis on variation rather than the mean. Additionally, the former treats noise as an extraneous factor, while the latter considers it as a central point of its analysis.Toraj andSafavi[8] applied Taguchi techniques in the optimizing the performance of vacuum membrane distillation system for water desalination. In the study, feed temperature in the range of 35°C to 55°C, feed flow rate of 15–60 mL/s, vacuum pressure of 30–130 mbar and feed concentration of 50-150 g/L were investigated. Application of ANOVA showed that all the operating parameters were significant, with each having different level of importance. The optimum permeate flux reported was 16.96 kg/m2h at 550C feed temperature, 30 mL/s feed flow rate, 50 g/L feed concentration and 30 mbar vacuum pressure.
II. Theory
The system considered in this studyis as depicted in fig.1. Itconsists of feed chamber and coolant chamber separated by a hydrophobic membrane material. In this configuration, heat and mass transfer occurs simultaneous. The feed temperature(푇푓)decreaseover the feed side boundary layer to 푇푚푓 at the membrane surface. As part of feed solution evaporates and diffusesthrough membrane pores, heat isconducted through membrane to the coolantchamber. The coolant temperature(푇푐)rises across the cold boundary layer to 푇푚푐as vapour condenses into the fresh water [9]. The driving force is hence the vapour pressure difference between 푇푚푓and푇푚푐, which is less than the vapour pressure difference between 푇푓 and푇푐. The process is otherwise called temperature polarization [10].
3. Dahiru U. Lawal Int. Journal of Engineering Research and Applications www.ijera.com
ISSN : 2248-9622, Vol. 4, Issue 8( Version 5), August 2014, pp.124-135
www.ijera.com 126|P a g e
Fig. 1. Schematic diagram of heat and mass transfer across MD membrane [11].
2.1 Mass Transfer
Mass transfer in MD takes place by convection and diffusion of vapour through the micro porous membrane sheet [11, 12]. In DCMD, both heat and mass transfer process takes place through the membrane as shown in figure1. The water permeate flux (퐽푊)obtained depends on the membrane characteristic and the created driving force. The mechanism of mass transfer in membrane pores is guided by three basic processes. Knudsen diffusion (K), Poiseuille (viscous)flow (P),Molecular diffusion (M) andtransition model are the mechanism themass transfer through the membrane pores.The general expression for mass transfer in MD is [11, 13]: 퐽푊=퐶푤Δ푃푚 (1)
Where 퐶푤is the overall mass transfer coefficient which is the reciprocal of an overall mass transfer resistance and Δ푃푚=푃푚푓 − 푃푚푐is the vapour pressure difference between the sides of the membranesheet. Thus: 퐽푊= 퐶푤 푃푚푓 − 푃푚푐 (2)
For pure water, 푃푚can be estimated fromAntoine equation [9]; 푃푚=푒푥푝 23.328− 3841 푇푚−45 (3) Khayet et al [14] showed that the permeate flux has a linear relation with the partial pressure difference across the membrane pores as given in eq. (4)when the feed is water and when the temperature difference through the membrane is low. 푃푚푓−푃푚푐= 푑푃 푑푇 푇푚 푇푚푓−푇푚푐 (4) Substitution of eq. (4) into (2) results in:
퐽푊= 퐶푤 푑푃 푑푇 푇푚 푇푚푓 − 푇푚푐 (5)
Where 푃푚푓and 푃푚푐are the transmembrane vapour pressure at the feed and coolant sides respectively.푇푚푓 and푇푚푐are the transmembrane temperature at the feed and permeate sides respectively. The term 푑푃 푑푇 푇푚 is obtained from the combination of Clausius–Clapeyron equation and the Antoine equation as given in [9]:
푑푃 푑푇 푇푚 = Δ퐻푣 푅푇푚2 푒푥푝 23.328− 3841 푇푚−45 (6)
WhereR is the gas constant, Tm is the mean temperature in kelvin given by 푇푚= 푇푚푓 + 푇푚푐 2 and Δ퐻푣is the heat of vapourisation of waterwhich is expressed as:
Δ퐻푣=1.7535T+2024.3 [kJ/kg] (7)
2.2 Membrane Permeability (퐂퐖)
Knudsen number (퐾푛) is the governingquantity which provides the guideline foridentifying which type of mechanism of mass transfer dominates the flow under the given experimental condition just like how Reynolds number is used as a guide in defining if a flow is laminar, turbulent and transitional. Based on kinetic theory of gases, the mechanism of mass transfer through DCMD membrane must be by Knudsen model or ordinary molecular diffusion or poiseuille (viscous) flow model or a combination of these models. Usually, viscous flow model neglected in DCMDbecause both feed and permeate solutions are maintained in direct contact withmembrane material under atmospheric. The total pressure is constant at atmospheric leading to negligible viscous kind of flow [11, 12, 15, 16]. The expression for Knudsen number is given as: 퐾푛= 휆푤 푑푝 (8)
Where 푑푝is the membranepore size and휆푤 is the mean free path of the water molecule which may be estimated from:
휆푤= 퐾퐵푇 2휋푃푚 2.641×10−10 2 (9)
Where 퐾퐵 is the Boltzmann constant, Pm is the mean pressure within the membrane pores, T is the absolute mean temperature in the pores (Kelvin).
When membrane pore size is low in comparison with mean free path of water molecules in vapour state (푑푝< 0.1휆푤), then the molecule-pore wall collisions preside over the molecule-molecule impact, so the Knudsen kind of flow is responsible
4. Dahiru U. Lawal Int. Journal of Engineering Research and Applications www.ijera.com
ISSN : 2248-9622, Vol. 4, Issue 8( Version 5), August 2014, pp.124-135
www.ijera.com 127|P a g e
for the mechanism of mass transfer. The expression below provides membrane permeability (퐶푤) in Knudsen region [4, 9, 17, 18]: 퐶푤= 2휋 31 푅푇 8푅푇 휋푀푤 1/2푟푘 3 휏훿 (10)
Where 푟푘is the membrane pore radius, 휏is the membrane tortuosity, 훿is the membrane thickness and 푀푤is the molecular mass of water.
When the mean free path of the transported water molecules in vapour state is less than the membrane pore size (푑푝>100휆푤), then the molecule- molecule collision is predominant over the molecule to pore wall, so ordinary molecular diffusion is responsible for the mass transfer in the continuum region. In this case, the below expression may be adopted to evaluate the membrane permeability [9, 18]; 퐶푊퐷 = 휋 푅푇 푃퐷푤 푃푎 푟퐷 2 휏훿 11
Where 푃푎 is the air pressure in the membrane, P is the total pressure inside the membrane pore and 퐷푤 is the diffusion coefficient which can be obtained from the following expressions [9, 19, 20, 21]: 푃퐷푤=1.895×10−5푇2.072 푃퐷푤=1.19×10−4푇1.75 (12) 푃퐷푤=4.46×10−6푇2.334
Where P퐷푤 is in Pa.m2/s
Transition region mechanism occurs when we 0.1휆푤<dp< 100휆푤.In this case, the molecules of liquid water collides with each other and diffuses through the air molecules. For transition region, combined Knudsen-ordinary molecular diffusion type of flow is responsible for the mass transfer. The model for membrane permeability for transition region is expressed as [9, 18]: 퐶푤 퐶= 휋 푅푇 1 휏훿 23 8푅푇 휋푀푤 12 푟푡 3 −1+ 푃퐷푤 푃푎 푟푡 2 −1 −1 (13) Membrane tortuosity can be estimated using the correlation suggested by Macki[22]:
휏= 2−휀 휀 2 (14)
Where휀 is the membrane porosity.
2.3 Heat Transfer
Heat transfer in (DCMD) involved three (3) major steps as depicted in fig. 1. The steps are:
i.Convection heat transfer in the feed boundary layer (푄푓) given by [9]: 푄푓= 푕푓 푇푓−푇푚푓 (15)
ii. Heat transfer across the membrane sheet (푄푚) is composed of latent heat of vaporization (푄푣) and conduction heat transferthrough the membrane material and the gas filling pores (푄푐). This is given as [9]: 푄푚=푄푐+푄푣 (16) Where 푄푣=퐽푤ΔHv=퐶푊 푑푃 푑푇 푇푚 푇푚푓−푇푚푐 Δ퐻푣 (17) And 푄퐶= −퐾푚 푑푇 푑푋 = 퐾푚 훿 푇푚푓−푇푚푐 (18) Combining Eqs. (16), (17) and (18) leads to: 푄푚= 퐾푚 훿 + 퐶푊 푑푃 푑푇 푇푚 Δ퐻푣 Δ푇푚 (19)
Where Δ푇푚= 푇푚푓−푇푚푐
iii.Heat transfer in the coolant boundary layer (푄푝) expressed as: 푄푝= 푕푝 푇푚푐−푇푐 (20) Different models has been employed in estimating thermal conductivity of the membrane material, but the following sets of equation is often used [9]:
퐾푚= 휀퐾푔+ 1−휀 퐾푝 (21) And the Isostress model [9, 20]:
퐾푚= 휀 퐾푔 + 1−휀 퐾푝 −1 (22)
Where 퐾푝 And 퐾푔 are the thermal conductivity of the membrane material and that of the gas filling the membrane pores respectively. At steady state, the overall heat transfer through the DCMD system is given by:
푄=푄푓 + 푄푚+푄푝 (23)
5. Dahiru U. Lawal Int. Journal of Engineering Research and Applications www.ijera.com
ISSN : 2248-9622, Vol. 4, Issue 8( Version 5), August 2014, pp.124-135
www.ijera.com 128|P a g e
Combination and manipulation of Eqs (15) to (20) leads to: 푇푚푓= 퐾푚 훿 푇푐+ 푕푓 푕푝 푇푓 +푕푓푇푓−퐽푤Δ퐻푣푤 퐾푚 훿 +푕푓 1+ 퐾푚 훿푕푝 24 푇푚푝= 퐾푚 훿 푇푓+ 푕푝 푕푓 푇푐 +푕푝푇푐+퐽푤Δ퐻푣푤 퐾푚 훿 +푕푝 1+ 퐾푚 훿푕푓 (25)
Eq. 24 and eq. 25 are the required temperature in eq. 3 and eq. 5. The heat transfer coefficients (푕푓푎푛푑푕푝) can be estimated from Nusselt number given as [17]:
푁푢푖= 푕푖푑푖 푘푖 푤푕푒푟푒푖=푓푎푛푑푝 (26) andk is the thermal conductivity of the fluid, d is the hydraulic diameter, h is the heat transfer coefficient and f is the feed and p is the permeate. For laminar flow, the following empirical correlation can be used [22, 23]:
푁푢=1.86 푅푒Pr 푑 퐿 0.33 (27) For turbulent flow, correlation below may be used[24]:
푁푢=0.023 푅푒0.8푃푟0.33 휇 휇푠 0.14 (28)
Where 푃푟 and 푅푒 are the Prandtl and Reynolds numbers respectively and they are expressedas: 푃푟= 휇퐶푃 푘 , 푅푒= 휌푢푑 휇 (29)
푤푕푒푟푒퐶푃,휌,푢,푎푛푑휇 arethe specific heat capacity, density, average velocity and viscosity of the liquid respectively.
For feed solution containing dissolve salt, 푃푚푓 may be estimated using the Raoult’s law expressed as [25]: 푃푚푓= 1−퐶푀푁푎푐푙 푃푚 (30)
Where, 퐶푀푁푎푐푙 is the molar solute concentration.
2.4 Simulation procedure
The solution to the above set of equations was implemented in Matlab. For flux prediction, aniterative method was adopted.Initially, guessed values were assigned for membrane surface temperatures(푇푚푓푎푛푑푇푚푐). The guessed values are then used to calculate thepermeate flux (퐽푊) as given in Eqs. (4) - (13), (27) and (28). The obtainedflux (퐽푤) from these guessvaluesis then utilized to calculate acorrected sets of membrane surface temperatures.The above procedures is repeated until the difference between two consecutive iterations is less than 0.1%.
III. Results and Discussions
To examine the flux prediction capability of the theoretical model, its results were validated against the experimental work of Andrjesdottir et al [26].The geometrical constants and the membrane properties used are tabulated in Table 1. Table1.Membrane Properties and Geometrical Constant Used [26]
Symbol
Values as used in[26]
δ ε Kg Kp dp R L W H A dh
140μm 0.88 0.029W/mK 0.259W/mK 0.20 μm 8.314J/Kmol 120mm 104mm 5.2mm 5.408 x 10-4 m2 9.905 x 10-3m
The minimum and maximum temperature considered in the experimental work are 150C and 600C respectively andconsidering the membrane pore sizes of 2 x 10-7as used in [26],it was confirmed by [11] that the best modelfor flux prediction in DCMD is the combined Knudsen-molecular diffusion kind of flow model. Hence the model to be adopted in this work.
Fig. 2. Flux vs. feed temperature in DCMD for theoretical model and experiment [26]. Coolant temperature is kept at 21oC, feed flow rate is 12 L/min and coolant flow rate is 4 L/min.
10
20
30
40
50
60
45
50
55
60
Permeate Flux [kg/m2hr]
Feed Temperature [oC]
Andrjesdottir et al [26] EXP
Theoretical Model
6. Dahiru U. Lawal Int. Journal of Engineering Research and Applications www.ijera.com
ISSN : 2248-9622, Vol. 4, Issue 8( Version 5), August 2014, pp.124-135
www.ijera.com 129|P a g e
Fig. 3. Effect of coolant temperature on flux for theoretical model and experiment [26]. Feed temperature is kept at 60oC, feed flow rate is 12 L/min and coolant flow rate is 4 L/min.
Fig. 4. Effect of flow rate on flux for theoretical model and experiment [26]. Coolant flow rate is 3 L/min, feed temperature is 600C, and coolant temperature is 210C. Depicted in Figs. 2-4 are the results of flux prediction using combined Knudsen-molecular diffusion kind of flow model. The selected model was used to investigate the effect of feed inlet temperature, coolant inlet temperature and feed flow rate. In all the cases, results shows good agreement between the model and the experiment with minimum percentage error of 0.00 % as obtained in Fig. 6 and maximum percentage deviation of 3.55 % as found in Fig. 4. Therefore, we are now save to employ the theoretical model in generating data for ANOVA and regression analysis which is our main objective in this study.
IV. Statistical Analysis
Statistical software MINITAB 16 was employed in the design and analysis of the datagenerated from the mathematical model. The five levels of parameters combination and the Taguchi L25 (54) orthogonal arrays for this combinations are tabulated in Table 2. In total, 25theoretical data were generated and the results are as presented in Table 2.The main effect plots are as depicted in fig. 5. The plots are effectively used to investigate the trends and influence of each factor (operating parameters). It is obvious from Fig. 5 that the permeate flux increases with increasing feed temperature. This is in fact due to the exponential rise in water vapour pressure [9, 25, 27, 28]. The permeate flux also increases with increasing feed flow rate and coolant flow rate. This can be attributed to the high turbulent generated in the channels because of higher mixing effect. This can also due to the fact that rise in flux can also be a result of increase in heat transfer coefficient in boundary layer at both feed and coolant sides of membrane which leads to reduction in temperature polarization effect. Reduction in permeate flux was however observed when coolant temperature rises. The drop in permeate flux is caused by the decrease in driving temperature difference between the feed side and condensation surface. It is obvious from the mean effect plots that the feed inlet temperature has the most significant effect on the system performance in comparison to other operating parameters. 4.1 ANOVA
The experimental data were subjected to statistical scrutiny via analysis of variance (ANOVA). ANOVA was performed in order to observe the significant effect of each operating parameters. The analysis was conducted at 95% confidence level (level of significant훼= 0.05). The obtained ANOVA results are tabulated in Table 3. It can be noticed that each factors has P-value less than the chosen confidence level (0.05). This is an indication that each operating factors are statistically significant. As such, we reject null hypothesis and accept alternative hypothesis.
However, it can be observed from Table 3 that feed temperature provides the most significant effect on the DCMD performance having P-value of 0.000. Next to feed temperature in level of significant effect on the system flux is the coolant temperature with P- value of 0.017, then the feed flow rate having P-value of 0.032. Coolant flow rate provides the least significant effect on permeate flux and its P-value is 0.04
30
35
40
45
50
55
60
65
70
18
20
22
24
26
Permeate Flux [kg/m2hr]
Coolant Temperature [oC]
Andrjesdottir et al [26] EXP
Theoretical Model
30
35
40
45
50
55
60
65
70
5
8
11
14
Permeate Flux [kg/m2hr]
Feed Flow Rate [L/min]
Andrjesdottir et al [26] EXP
Theoretical Model
8. Dahiru U. Lawal Int. Journal of Engineering Research and Applications www.ijera.com
ISSN : 2248-9622, Vol. 4, Issue 8( Version 5), August 2014, pp.124-135
www.ijera.com 131|P a g e
40 50 60 70 80
120
90
60
30
10 15 20 25 30
2 4 6 8 10
120
90
60
30
1 3 5 7 9
Feed Temperature [C]
Permeate Flux [kg/m2hr]
Coolant Temperature [C]
Feed Flowrate [L/min] Coolant Flowrate [L/min]
Main Effects Plot for DCMD Parameters
Figure 5: Main effect plot of the permeate flux
-7.5 -5.0 -2.5 0.0 2.5 5.0
99
95
90
80
70
60
50
40
30
20
10
5
1
Residual
Percent
Normal Probability Plot
(response is permeate flux)
0 20 40 60 80 100 120 140
5.0
2.5
0.0
-2.5
-5.0
Fitted Value
Residual
Versus Fits
(response is Permeate flux)
Figure 6: Normal probability plot Figure 7: Residuals vs fits plot
Table 3: Analysis of variance for responses, using adjusted SS for tests
Source DF Seq SS Adj SS Adj MS F P
Feed Temperature [C] 4 34568.9 34568.9 8642.23 453.32 0.000
Coolant Temperature [C] 4 448.5 448.5 112.13 5.88 0.017
Feed Flow rate [L/min] 4 267.2 267.2 66.79 3.50 0.032
Coolant Flow rate [L/min] 4 184.3 184.3 46.07 2.42 0.048
Residual Error 8 152.5 152.5 19.06
Total 24 35621.4
9. Dahiru U. Lawal Int. Journal of Engineering Research and Applications www.ijera.com
ISSN : 2248-9622, Vol. 4, Issue 8( Version 5), August 2014, pp.124-135
www.ijera.com 132|P a g e
Fig. 6 displays normality plots of residuals. It was observed that the theoretical data point either passes through the mean line (fitted line) or clusters around it. This is an indication that neither normality assumption was violated nor any evidence pointing to possible outliers. As such, we conclude that normal distribution is an approximate model for the system performance. Thus, the mean data generated is normally distributed along the fitted line. Fig. 7 depicts the residuals against fitted values. The tendency to have runs of positive and negative residuals indicates positive correlation which validates independence assumption. It is obvious from fig. 7 that no recognized pattern exist. This implies that the constant variance assumption holds.
4.2 Regression Modelling
In model generation, permeate flux was modeled as dependent variable while the feed temperature, coolant temperature, feed flow rateand coolant flow rate as independent variables. Prior to model generation, the actual response surface was plotted in order to have the general idea of the suitable variables function that will enable the smooth fitting of the model to the actual response surface. Following which potential suitable models were generated, first, with feed temperature, coolant temperature and feed flow rate as variables. Thereafter, all other possible suitable combinations were generated, including quadratic terms depending on the shape of the actual response plane. Comparisons were then made and the best model to represent the property change was selected based on the adjusted correlation coefficient value (R2 (adj)) and standard error of estimate (S) of each model.
Thus, the best subsets regression approach was adopted during model generation. In this approach, all possible regression equations were estimated using all possible combinations of independent variables. The best fit of the model was selected based on the highest adjusted R-square and lowest standard error estimate (S). Thus, the best regression model for predicting permeates flux is given by: Y=69.9139−3.26298A+0.0485245A2−0.587518B+1.14602C+0.925844D(31) Where Y is the predicted permeate flux [kg/m2h], A is the Feed temperature [oC], B is the Coolant Temperature [oC], C is the Feed flow rate [L/min] and D is the coolant flow rate [L/min]. It can be observed from Table 4 that the regression model is significant with P-Value of 0.0000000. The generated model has R-Square of 99.04%, meaning that 99.04% of variation in permeate flux is captured by variation in feed temperature, coolant temperature, feed flow rate and coolant flow rate. The model also has adjusted R-Sq of 98.79%, signifying that 98.79% of variation in permeate flux is explained by variation in feed temperature, coolant temperature, feed flow rate and coolant flow rate, taking into account the theoretical data size and number of independent variables. The model also has a standard error estimate (S) of 4.23340 and (S) is the measure of variation of observed permeate flux (J) from the regression line. It is worth noting that the magnitude of S is judged based on the relative size of the system performance values in the theoretical data. The general conclusion is that; the lower the S value, the better the generated model.
Analysing the terms in the regression equation, the highest positive main effect is contributed by feed inlet temperature (variable A in Eq. 31). While the feed inlet temperature has a linear negative main effect on the flux, its quadratic positive term (A2) overrun the negative effect of the linear term. Hence increasing this term (A) led to tremendous increases in permeate flux. The maximum negative main effect is attributed to the cooing inlet temperature (variable B in Eq. 31), meaning that increasing this term will result in reduction in the permeate flux. Table 4: Analysis of variance for responses, using adjusted SS for tests
Source DF Seq SS Adj SS Adj MS F P
Regression 5 35280.9 35280.9 7056.18 393.723 0.0000000 A 1 32767.1 512.6 512.58 28.601 0.0000368 B 1 431.5 431.5 431.47 24.075 0.0000980 C 1 262.7 262.7 262.67 14.657 0.0011338 D 1 171.4 171.4 171.44 9.566 0.0059894 A (SQR) 1 1648.2 1648.2 1648.24 91.969 0.0000000 Error 19 340.5 340.5 17.92
S = 4.23340 R-Sq = 99.04% R-Sq(adj) = 98.79%
10. Dahiru U. Lawal Int. Journal of Engineering Research and Applications www.ijera.com
ISSN : 2248-9622, Vol. 4, Issue 8( Version 5), August 2014, pp.124-135
www.ijera.com 133|P a g e
Both feed and coolant inlet flow rate (variables C and Drespectively in Eq. 31) each has little positive main effect on DCMD system performance. This is an indication that increasing these terms will result in small increment in system performance.
4.3 Regression Model Validation
The generated regression model was subsequently used to predict permeate flux. Comparison wasmade between the prediction of regression model and theoretical model.The outcomes were then tabulated in Table 2. It can be observed fromTable2 that both regression model results and that of theoretical model were in good agreementwith the maximum percentage error of 1.098%. Effort was also made to validate the regression model against the experimental data of Andrjesdottir et al [26] as depicted in fig. 8-10.For the effect offeed inlet temperature, the maximum percentage error recorded was 2.98% and that of coolant temperature was found to be 0.49%, while that of feed flow rate happened to be 1.68%. The prediction of this close accuracy to the experimental data is an indication that the developed regression model has the capacity to adequately predict DCMD permeate flux. Hence, based on statistical analysis, the developed model is considered suitable for predicting DCMD system perforance within the domain of theoretical inputs.
Fig. 8. Flux vs. feed temperature in DCMD for the models and experiment [26]. Coolant temperature is kept at 210C, feed flow rate is 12 L/min and coolant flow rate is 4 L/min.
Fig. 9. Effect of coolant temperature on flux for the models and experiment [26]. Feed temperature is kept at 60 0C, feed flow rate is 12 L/min and coolant flow rate is 4 L/min.
Fig. 10. Effect of flow rate on flux for the models and experiment [26]. Coolant flow rate is 3 L/min, feed temperature is 60 0C, and coolant temperature is 21 0C.
V. Conclusion
The basic concepts of heat and mass transfer analysis had been performed to portray the effect operating parameterson DCMD system performance.Taguchi method and applied regression were employed to model DCMD system for water desalination.Both the theoretical and regressionmodels were tested on the effect feed temperature, feed flow rate coolant temperature and coolant flow rate. Results arevalidated against the experimental work of Andrjesdottir et al [26]. Theoretical model prediction showed a good match with the experimental results used for validation. For the regression equation, the maximum overall positive effect is attributed to feed inlet temperature and the highest negative main effect is observed from coolant inlet temperature. Both feed and coolant flow rateshave little main effect on DCMD system performance.
10
20
30
40
50
60
45
50
55
60
Permeate Flux [kg/m2hr]
Feed Temperature [oC]
Andrjesdottir et al [26] EXP
Theoretical Model
Regression Model
30
35
40
45
50
55
60
65
70
18
20
22
24
26
Permeate Flux [kg/m2hr]
Coolant Temperature [oC]
Andrjesdottir et al [26] EXP
Theoretical Model
Regression Model
30
35
40
45
50
55
60
65
70
5
8
11
14
Permeate Flux [kg/m2hr]
Feed Flow Rate [L/min]
Andrjesdottir et al [26] EXP
Theoretical Model
Regression Model
11. Dahiru U. Lawal Int. Journal of Engineering Research and Applications www.ijera.com
ISSN : 2248-9622, Vol. 4, Issue 8( Version 5), August 2014, pp.124-135
www.ijera.com 134|P a g e
VI. Acknowledgment
The authors would like to thank King Fahd University of Petroleum & Minerals (KFUPM) for providing all the necessary support needed in this work under the funded project # IN121043. References [1] A.S. Jonsson, R. Wimmerstedt, and A.-C. Harrysson, Membrane distillation-A theoretical study of evap. through microporous membranes,Desalination, vol. 56, pp. 1985, 237-249.
[2] L. Martínez, and F.J. Florido-Díaz, Theoretical and experimental studies on desalination using membrane distillation, Desalination, vol.139(1–3),2001,pp. 373- 379. [3] J. M. Li, Z. K. Xu, Z. M. Liu, W. F. Yuan, H. Xiang, S. Y. Wang, Y. Y. Xu, Microporous polypropylene and polyethylene hollow fiber membranes. Part 3. Experimental studies on membrane distillation for desalination,Desalination, vol. 155(2), 2003, pp. 153-156.
[4] R.W. Field, H.Y. Wu, J. J. Wu, Multiscale Modeling of Membrane Distillation: Some Theoretical Considerations,Industrial&Engineering Chemistry Research, vol. 52 (26), 2013, pp. 8822–8828. [5] T. Y. Cath, V.D. Adams, A.E. Childress, Experimental study of desalination using direct contact membrane distillation: a new approach to flux enhancement,Journal of Membrane Science, vol. 228(1), 2004, pp. 5-16. [6] M. Khayet, C. Cojoucaru, Air gap membrane distillation: Desalination, modeling and optimization, Desalination 287, 2012, 138-145. [7] S. S. Madaeni,S. Koocheki,Application of Taguchi method in the optimization of wastewater treatment using spiral-wound reverse osmosis element, Chemical Engineering Journal 119, 2006, 37–44. [8] M. Toraj,M. A. Safavi,Application of Taguchi method in optimization of desalination by vacuum membrane distillation, Desalination 249: 2009, 83–89. [9] M. Khayet, T. Matsuura, Membrane distillation principles and applications, (Elservier B.V. 2011, ch. 10, pp. 254-268). [10] L. M. Camacho, L. Dumee, J. Zhang, J. li, M. Duke, J. Gomez, S. Gray,Advances in Membrane Distillation for Water Desalination and Purification Application, Water,vol. 5,2013, p. 94-196. [11] U. L. Dahiru, E. A. Khalifa, Flux prediction in Direct contact membrane distillation, International Journal of Materials, Mechanics and Manufacturing, vol.2, No. 4 2013.. [12] R.W. Schofield, A.G. Fane, C.J.D. Fell, Heat and mass transfer in membrane distillation, Journal of Membrane. Science, vol.33, 1987, pp. 299-313. [13] J. Zang, N. Dow, M. Duke, E. Ostarcevic, J. D. Li, S. Gray, Identification of material and physical features of membrane Distilation. Membrane for high performance desalination,Journal of Membrane Science, vol. 349, 2010, pp. 295-303. [14] M. Khayet, P. Godino, J. I. Mengual, Study of asymmetric polarization in direct contact membrane distillation, Separation Science and Technology, vol. 39, 2005, pp. 125–147. [15] R.W. Schofield, A.G. Fane, C.J.D. Fell, Factors affecting flux in membrane distillation, Desalination, vol. 77, 1990, pp. 279–294. [16] R.W. Schofield, A.G. Fane, C.J.D. Fell, Gas and vapour transport through micro porous membranes. II. Membrane distillation, Journal of Membrane Science, vol. 53 (1– 2),1990, pp. 173–185. [17] A. Alkhudhiri, N. Darwish, N. Hilal, Membrane distillation: A comprehensive review, Desalination, vol.287, 2012, pp.2– 18. [18] M. Khayet, A. Velázquez, J.I. Mengual, Modelling mass transport through a porous partition: effect of pore size distribution, Journalof Non-Equilibrium Thermodynamics, vol. 29 (3), 2004, pp. 279–299. [19] R.W. Schofield, A.G. Fane, C.J.D. Fell, Gas and vapour transport through micro porous membrane I. Knudsen–Poiseuille transition,Journal of Membrane. Science. vol. 53 (1–2), 1990, pp. 159–171. [20] J. Phattaranawik, R. Jiraratananon, A.G.Fane,Effect of pore size distribution and air flux on mass transport in direct contact membrane distillation, Journal of Membrane Science, vol. 215, 2003, pp. 75– 85. [21] Y. Yun, R. Ma, W. Zhang, A. G. Fane, J. Li, Direct contact membrane distillation mechanism for high concentration NaCl solutions,Desalination, vol. 188,2005, pp. 251–262.
[22] S. Srisurichan, R. Jiraratananon, A.G. Fane, Mass transfer mechanisms and transport resistances in direct contact membrane
12. Dahiru U. Lawal Int. Journal of Engineering Research and Applications www.ijera.com
ISSN : 2248-9622, Vol. 4, Issue 8( Version 5), August 2014, pp.124-135
www.ijera.com 135|P a g e
distillation process, Journal of Membrane Science, vol. 277 (1–2), 2006,pp. 186–194. [23] L. Martínez-Díez, M. I. Vázquez- González,Temperature and concentration polarization in membrane distillation of aqueous salt solutions, Journal of Membrane Science, vol. 156 (2), 1999, pp. 265–273. [24] K.W. Lawson, D.R. Lloyd, Membrane distillation,Journal of Membrane Science, vol. 124 (1), 1997, pp. 1–25. [25] M.N.A. Hawlader, R. Bahar, K. C. Ng, L. J. W. Stanley.Transport analysis of an air gap membrane distillation (AGMD) process,Desalination &Water Treatment, vol. 42, 2012, pp. 333–346. [26] O. Andrjesdottir, C. L. Ong, M. Nabavi, S. Paredes, A.S.G. Khalil , B. Michel, D. Poulikakos. An experimentally optimized model for heat and mass transfer in direct contact membrane distillation,International Journal of Heat and Mass Transfer, vol. 66, 2013, pp. 855–867. [27] F. A. Banat,J. Simandl,Membrane distillation for dilute ethanol: Separation from aqueous streams, Journal of Membrane Science 163: 1999, 333-348. [28] M. A. Izquierdo-Gil,M. C. Garcia-Payo, C. F. Pineda,Air gap membrane distillation of sucrose aqueous solutions, J. Membr. Sci. 155: 1999, 291-307.
Nomenclature A Cross sectional area [m2] dp Pore size [μm] dh Hydraulic diameter [m] D Diffusion coefficient [m2/s] h Heat transfer coefficient [W/m2K] Hv Heat of vapourisation [kJ/kg] Jw Permeate flux [kg/m2hr]
K Thermal conductivity [W/mK]
Cw Mass transfer coefficient [kg/m2sPa] Km Membrane thermal conductivity [W/mK] Kg Thermal conductivity of gas filling the pores [W/mK] Kp Thermal conductivity of membrane material [W/mK] Kn Knudsen number [dimensionless number] Mw Molecular weight [g/mol] Nu Nusselt Number [dimensionless number] P Total pressure [Pa] Pm Mean Pressure [Pa] Pr Prandtl Number [dimensionless number] Qs Sensible heat transfer [W/m2] Qv Latent heat transfer [W/m2] Qc Conduction heat transfer [W/m2] R Gas constant [J/Kmol] Re Reynolds number [dimensionless number] Sc Schmidt number [dimensionless number] Sh Sherwood number [dimensionless number] T Absolute temperature [K] Subscripts and Superscripts f Feed p Permeate m Membrane b Bulk mf Feed side of membrane mp Coolant side of membrane f Bulk feed c Bulk permeate s surface Greek Letters δ Membrane thickness; film thickness [μm]
ε Porosity [%]
τ Tortuosity [No unit]
μ Viscosity [Ns/m2]
λ Mean free path [m] V kinematic viscosity [m2/s]
ρ Density [kg/m3]