Mamdouh Assad | University of Sharjah (original) (raw)

Papers by Mamdouh Assad

Unmanned Systems Technology XXII

This dissertation analyzes the politics of the conflict between the advocates of physician-assist... more This dissertation analyzes the politics of the conflict between the advocates of physician-assisted suicide in Hawaii and their opponents. The first part of this dissertation examines the role of society in deciding whether the individual's decisions regarding end of life treatment should be governed by morals, ethics and beliefs maintained under the status quo or whether such decisions should also include the option of physician assisted suicide under strict conditions. This part of the study seeks to answer the questions, "What are the end-of-life options that define a "good death" and what are the arguments imbedded in the issue of physician assisted suicide? The second part of this dissertation addresses the politics of winning the battle of physician assisted suicide legislation in Hawaii. The empirical focus is a small group of individuals joined together by their beliefs in choice and autonomy and who propose legislation to legalize PAS. They are opposed by a bigger and better financed group with ties to organized religion, to health care professionals and to groups whose members have disabilities. In 2002, except for three votes, the advocates almost win. Despite their continued attempts, the advocates have not repeated their "near win." Challenged by the death of their leader, the lack of financial resources and a declining membership, the sustainability and viability of the advocates are in question. This dissertation concludes by proposing a strategy that may further their attempts to win. vi

Design and Performance Optimization of Renewable Energy Systems

Abstract In this chapter a brief summary about on- and offshore wind turbines is presented. Energ... more Abstract In this chapter a brief summary about on- and offshore wind turbines is presented. Energy and exergy analyses of wind turbines are presented, for which a numerical example of a wind turbine located in Tehran, Iran is demonstrated. The results show that the energy and exergy efficiency may reach 35.7% in May and 13.5% in December, respectively.

2019 Advances in Science and Engineering Technology International Conferences (ASET)

In this paper, the performance of Nano-enhanced phase change material was studied. Phase change m... more In this paper, the performance of Nano-enhanced phase change material was studied. Phase change material (PCM) has a high energy density that sets it at the forefront of energy storage material. However, the power density of PCM is low due to its low thermal conductivity, which results in a decrease in the rate of heat transfer. After comparing Carbon nanofibers (CNF), to metal embedded Nano-fibers as PCM additives, it was concluded that CNF has a better effect on the thermal conductivity of PCM material. Results indicated that the thermal conductivity was enhanced significantly by adding 1 weight percent of carbon Nano-fibers to the phase change material. A numerical model was developed to predict the behavior of the Nano-enhanced material given the modified properties.

The Earth is made up of 71% water, but the world still has water shortage, so what is the reason?... more The Earth is made up of 71% water, but the world still has water shortage, so what is the reason? The answer to that question is that 97% of the water available is salty water, and all of it has high salt content, which makes is impossible for drinking, consuming, and irrigation. The solution for this problem is desalination, it is the only way that we can get drinkable water, other than fresh resources. But desalination usually consumes a huge amount of electricity, so other sustainable sources to help in the process of desalination in a cleaner and more cost-effective way should be considered. In this work, two main technologies for water desalination using geothermal-powered systems are presented and discussed. These technologies are promising, especially in gulf region, where geothermal energy is available generously.

Journal of Thermal Analysis and Calorimetry

Exergy approach is essential for the design and possible operation of the absorption system with ... more Exergy approach is essential for the design and possible operation of the absorption system with energy loss minimization. Operational limitations of absorption refrigeration system are due to Gibbs phase rules-base. Optimized operational decision rules are extracted from machine learning algorithm C4.5 which is suitable for different exergy evaluation methods and reference conditions. This study investigates proposed and investigated classification models for the same which are based on different thermodynamic features and operational design data. ANN model is used to predict the thermodynamic properties of the working fluids using improved thermodynamics properties of data patterns. Mathematical expressions are formulated from validated artificial neural network for predicting specific enthalpy and entropy of water–lithium bromide solution. Exergy design data are estimated on 356 thermodynamic design data pattern of absorption refrigeration system by MATLAB Simulators. Pearson’s correlation heatmap is used for extracting 14 thermodynamic features. 94.38% is the highest performance observed with 12 feature class six classification model.

In this chapter, the basic principles of Artificial Neural Network (ANN) and Fuzzy Logic (FL) are... more In this chapter, the basic principles of Artificial Neural Network (ANN) and Fuzzy Logic (FL) are presented. Procedures to use Particle Swarm Algorithm, Salp Swarm Algorithm, Grey Wolf Algorithm, Genetic Algorithm and Simulated Annealing are demonstrated and presented. Numerical examples about these methods are given in detail.

Given the growing global demands on energy and fresh water, nuclear energy has become a promising... more Given the growing global demands on energy and fresh water, nuclear energy has become a promising source of power and freshwater production. Maximizing the nuclear power plant efficiency requires running the plant at maximum power capacity, however, the actual load might not require such huge power supply (1000 MWe +). Power plants operation with high to maximum efficiency has a profound effect on financial prices and environmental conditions for clear reasons which commands the attention towards various expensive and not efficient energy storage techniques (thermal, electrical and hydro). In this work, energy storage is substituted by a desalination plant that utilizes the excess energy to power the desalination unit. Therefore, this work explores the potential of water desalination as a proxy for energy storage systems in nuclear power plants. Various water desalination technologies are examined and compared in terms of economy, water quality and production capacity. Barakah nucle...

This paper contains a comparison of several sigma-point Kalman filters, including the unscented K... more This paper contains a comparison of several sigma-point Kalman filters, including the unscented Kalman filter (UKF), the cubature Kalman filter (CKF), and the central difference Kalman filter (CDKF). The comparison is based on a simulated electro-hydrostatic actuator, which is commonly used for flight surface actuation in aerospace systems. This brief study compares the response, convergence rate, root mean square error, the maximum absolute error, and the stability of these sigma-point Kalman filters.

Case Studies in Thermal Engineering

Abstract This work presents a case study of thermodynamic performance of a condenser used in a 21... more Abstract This work presents a case study of thermodynamic performance of a condenser used in a 210 MW thermal power station at Mejia in West Bengal, India. The analysis involves an improvement of actual overall heat transfer coefficient by varying tube materials and fouling resistance. Exergy Destruction Factor (EDF) is introduced to quantify the percentage of exergy loss from the condenser wall. From this study, it is revealed that the second law performance of the condenser increases with the increase in thermal conductivity of the tube materials, decreases with the increase in fouling resistance and decreases with the increase in condenser pressure at the turbine outlet. The actual overall heat transfer coefficient can be increased up to 6% by selecting better conducting tube materials. While the EDF decreases with the increase in cooling water temperature rise and increases with the increase in cooling water inlet temperature, EDF is found to decrease with the increased cooling water mass flow rate.

2019 Advances in Science and Engineering Technology International Conferences (ASET)

Nowadays, the application of renewable energy sources is one of the primary goals to contribute t... more Nowadays, the application of renewable energy sources is one of the primary goals to contribute to low greenhouse gas emissions and low energy cost. Geothermal energy is one of the most attractive renewable energy sources that can be exploited at low, medium and high enthalpy. Absorption chillers are cooling machines that can be powered by a low-grade geothermal energy source. The geofluid leaving the power plant can be used to provide heat for the desorber before it is reinjected to the reinjection well. In this work, a thermodynamic analysis of parallel flow double effect water/LiBr absorption chiller driven by geothermal energy is presented. The effects of many design parameters such as temperature, mass flow rate, and heat exchanger size on the coefficient of performance (COP) and cooling load are investigated. An Engineering Equation Solver (EES) is used for that purpose. The results are presented in graphical forms to show the chiller performance behavior under different operating conditions. The results show that COP and cooling load can reach about 1.43 and 420 kW for certain operating and design conditions.

Energy Engineering

The energy coming from solar radiation could be harvested and transformed into electricity throug... more The energy coming from solar radiation could be harvested and transformed into electricity through the use of solar-thermal power generation and photovoltaic (PV) power generation. Placement of solar collectors (thermal and photovoltaic) affects the amount of incoming radiation and the absorption rate. In this research, new correlations for finding the monthly optimum slope angle (OSA) on flat-plate collectors are proposed. Twelve equations are developed to calculate the monthly OSA by the linear regression model, for the northern and the southern hemisphere stations from 15°to 55°and-20°to-45°, respectively. Also, a new equation for calculating the yearly tilt angle is developed and compared with several other calculation methods from the literature. Results confirm a 20% increase in solar energy absorption by adjusting the collectors' tilt angle in monthly time periods. This is while the adjusted collectors with the yearly optimum slope angle receive approximately 7% higher solar radiation compared to the horizontal collectors. Furthermore, the proposed equations outperformed the other calculation methods in the literature.

International Journal of Mechanical Engineering Education, 1997

A thermodynamic analysis of a real waste-heat thermoelectric generator is investigated. The therm... more A thermodynamic analysis of a real waste-heat thermoelectric generator is investigated. The thermoelectric generator is considered as a heat engine cycle process with internal irreversibilities. The efficiency of the thermoelectric generator is expressed in terms of two non-dimensional parameters which are to be optimized. A finite-time thermodynamic analysis is used to optimize the temperatures of the hot and cold junctions of the real thermoelectric generator. A comparison between ideal and real waste-heat thermoelectric generators is demonstrated.

This chapter describes the fundamentals of air handling processes and equipment and answers to qu... more This chapter describes the fundamentals of air handling processes and equipment and answers to questions related to the theoretical background of air handling unit and ductwork dimensioning and building energy systems optimization. It deals with the basic air-handling processes: filtration of particles and gaseous substances from the supply and recirculated air, air heating and cooling, heat-recovery processes, and humidification and dehumidification; equipment space requirements, associated components, and the pressure losses of various components, good design practices, including system balancing and efficient running; and essential factors in the selection of systems and equipment during the design stage. On the system level, considerable efforts have been made to reduce the heating and cooling demands, and the electrical energy consumption has been regarded as a marginal part. In ductwork design, attention must be paid to reduce energy losses using properly designed fittings and proper duct sizing.

International Journal of Energy Research, 2000

A theoretical model to study the performance characteristics of a magnetohydrodynamic (MHD) power... more A theoretical model to study the performance characteristics of a magnetohydrodynamic (MHD) power plant is presented. The model takes into account the external and internal irreversibilities. General expressions for power and e$ciency of the power plant are derived when the MHD generator is operating at constant velocity and constant Mach number conditions. It is shown that when the generator and compressor are running reversibly, the constant velocity and constant Mach number cases are identical in performance and the e$ciency at maximum power is identical to Curzon}Ahlborn e$ciency. It is also shown that the constant velocity case produces less entropy generation in the generator than that of the constant Mach number case when the generator electrical e$ciency is less than one.

Case Studies in Thermal Engineering

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Computers, Materials & Continua

CO 2 emission is considerably dependent on energy consumption and on share of energy sources as w... more CO 2 emission is considerably dependent on energy consumption and on share of energy sources as well as on the extent of economic activities. Consequently, these factors must be considered for CO 2 emission prediction for seven middle eastern countries including Iran, Kuwait, United Arab Emirates, Turkey, Saudi Arabia, Iraq and Qatar. In order to propose a predictive model, a Multilayer Perceptron Artificial Neural Network (MLP ANN) is applied. Three transfer functions including logsig, tansig and radial basis functions are utilized in the hidden layer of the network. Moreover, various numbers of neurons are applied in the structure of the models. It is revealed that using MLP ANN makes it possible to accurately predict CO 2 emission of these countries. In addition, it is concluded that using logsig transfer function leads to the highest accuracy with minimum value of mean squared error (MSE) which is followed by the networks with radial basis and tansig transfer functions. The R-squared of the networks with logsig, radial basis and tansig transfer functions are 0.9998, 0.9997 and 0.9996, respectively. Finally, comparison of the proposed model with a similar study, considered five countries in the same region, reveals higher accuracy in term of MSE.

Nanofluid is mixture between nanoparticle and base fluid, this mixture is used to enhance the hea... more Nanofluid is mixture between nanoparticle and base fluid, this mixture is used to enhance the heat transfer process inside heat exchangers. In this work, three alternatives of nanofluid based on CuO and TiO2 were studied inside concentric tube heat exchanger. Different volume fractions (0.05 % and 0.2 %) and mass flow rates (0.05 kg/sec and 0.25 kg/sec) were tested. 3-D numerical simulation was performed using computational fluid dynamic (CFD) for all nanofluid types under the same volume fraction (0.2 %). The numerical results showed that CuO nanofluid has the highest enhancement heat transfer ratio among the others two types where these augmentation ratios were 47% and 61 % for TiO2 and CuO respectively, while experimental results showed that these augmentation ratios were 48% and 50 % for TiO2, and CuO respectively at volume fraction 0.05 % and 30% and 62% for TiO2 and CuO respectively at volume fraction 0.2 %.

The depletion of fossil fuel energy resources, increasing concern of air pollution, global warmin... more The depletion of fossil fuel energy resources, increasing concern of air pollution, global warming and energy crisis have encouraged the research to develop innovative alternatives in engineering systems. This work presents a problem of minimizing the life cycle cost (as an economic criterion) of an air conditioning system for vapor compression and maximizing the useful heat (as a thermodynamic criterion). The mathematical model that represents the objective function has four decision variables: evaporation temperature and condensation temperature of the refrigerant, and volumetric flow rate of air in the condenser and the evaporator. The problem is a global optimization and the search method of solution is genetic algorithm. A thermodynamic model included design of exchanger. The methodology used is for R-1234yf, a low GWP refrigerant, which is R-134a refrigerant substitute.

The solar power tower system (SPTS) has been successfully demonstrated as a favorable candidates ... more The solar power tower system (SPTS) has been successfully demonstrated as a favorable candidates to replace fossil fuel energy systems. Although several investigations have been developed to assess the SPTS, the detailed, fundamentals-based, long-term transient simulation capability is limited. Research presented in this chapter is intended to indicate how artificial intelligence (AI) techniques may play an important role to address this need. For this purpose, a method of AI is developed to simulate a solar power tower direct steam (SPTDS) system. As a matter of fact, this hybrid method is developed through the combination of adaptive neurofuzzy inference system with biogeography-based optimization algorithm. The power losses from the receiver, power absorbed by the receiver, receiver thermal efficiency, field optical focus fraction, field optical efficiency, and the cycle electrical power output are simulated and appraised through the intelligent method. A set of input parameters ...

Procceedings of the 18th Brazilian Congress of Thermal Sciences and Engineering

Unmanned Systems Technology XXII

This dissertation analyzes the politics of the conflict between the advocates of physician-assist... more This dissertation analyzes the politics of the conflict between the advocates of physician-assisted suicide in Hawaii and their opponents. The first part of this dissertation examines the role of society in deciding whether the individual's decisions regarding end of life treatment should be governed by morals, ethics and beliefs maintained under the status quo or whether such decisions should also include the option of physician assisted suicide under strict conditions. This part of the study seeks to answer the questions, "What are the end-of-life options that define a "good death" and what are the arguments imbedded in the issue of physician assisted suicide? The second part of this dissertation addresses the politics of winning the battle of physician assisted suicide legislation in Hawaii. The empirical focus is a small group of individuals joined together by their beliefs in choice and autonomy and who propose legislation to legalize PAS. They are opposed by a bigger and better financed group with ties to organized religion, to health care professionals and to groups whose members have disabilities. In 2002, except for three votes, the advocates almost win. Despite their continued attempts, the advocates have not repeated their "near win." Challenged by the death of their leader, the lack of financial resources and a declining membership, the sustainability and viability of the advocates are in question. This dissertation concludes by proposing a strategy that may further their attempts to win. vi

Design and Performance Optimization of Renewable Energy Systems

Abstract In this chapter a brief summary about on- and offshore wind turbines is presented. Energ... more Abstract In this chapter a brief summary about on- and offshore wind turbines is presented. Energy and exergy analyses of wind turbines are presented, for which a numerical example of a wind turbine located in Tehran, Iran is demonstrated. The results show that the energy and exergy efficiency may reach 35.7% in May and 13.5% in December, respectively.

2019 Advances in Science and Engineering Technology International Conferences (ASET)

In this paper, the performance of Nano-enhanced phase change material was studied. Phase change m... more In this paper, the performance of Nano-enhanced phase change material was studied. Phase change material (PCM) has a high energy density that sets it at the forefront of energy storage material. However, the power density of PCM is low due to its low thermal conductivity, which results in a decrease in the rate of heat transfer. After comparing Carbon nanofibers (CNF), to metal embedded Nano-fibers as PCM additives, it was concluded that CNF has a better effect on the thermal conductivity of PCM material. Results indicated that the thermal conductivity was enhanced significantly by adding 1 weight percent of carbon Nano-fibers to the phase change material. A numerical model was developed to predict the behavior of the Nano-enhanced material given the modified properties.

The Earth is made up of 71% water, but the world still has water shortage, so what is the reason?... more The Earth is made up of 71% water, but the world still has water shortage, so what is the reason? The answer to that question is that 97% of the water available is salty water, and all of it has high salt content, which makes is impossible for drinking, consuming, and irrigation. The solution for this problem is desalination, it is the only way that we can get drinkable water, other than fresh resources. But desalination usually consumes a huge amount of electricity, so other sustainable sources to help in the process of desalination in a cleaner and more cost-effective way should be considered. In this work, two main technologies for water desalination using geothermal-powered systems are presented and discussed. These technologies are promising, especially in gulf region, where geothermal energy is available generously.

Journal of Thermal Analysis and Calorimetry

Exergy approach is essential for the design and possible operation of the absorption system with ... more Exergy approach is essential for the design and possible operation of the absorption system with energy loss minimization. Operational limitations of absorption refrigeration system are due to Gibbs phase rules-base. Optimized operational decision rules are extracted from machine learning algorithm C4.5 which is suitable for different exergy evaluation methods and reference conditions. This study investigates proposed and investigated classification models for the same which are based on different thermodynamic features and operational design data. ANN model is used to predict the thermodynamic properties of the working fluids using improved thermodynamics properties of data patterns. Mathematical expressions are formulated from validated artificial neural network for predicting specific enthalpy and entropy of water–lithium bromide solution. Exergy design data are estimated on 356 thermodynamic design data pattern of absorption refrigeration system by MATLAB Simulators. Pearson’s correlation heatmap is used for extracting 14 thermodynamic features. 94.38% is the highest performance observed with 12 feature class six classification model.

In this chapter, the basic principles of Artificial Neural Network (ANN) and Fuzzy Logic (FL) are... more In this chapter, the basic principles of Artificial Neural Network (ANN) and Fuzzy Logic (FL) are presented. Procedures to use Particle Swarm Algorithm, Salp Swarm Algorithm, Grey Wolf Algorithm, Genetic Algorithm and Simulated Annealing are demonstrated and presented. Numerical examples about these methods are given in detail.

Given the growing global demands on energy and fresh water, nuclear energy has become a promising... more Given the growing global demands on energy and fresh water, nuclear energy has become a promising source of power and freshwater production. Maximizing the nuclear power plant efficiency requires running the plant at maximum power capacity, however, the actual load might not require such huge power supply (1000 MWe +). Power plants operation with high to maximum efficiency has a profound effect on financial prices and environmental conditions for clear reasons which commands the attention towards various expensive and not efficient energy storage techniques (thermal, electrical and hydro). In this work, energy storage is substituted by a desalination plant that utilizes the excess energy to power the desalination unit. Therefore, this work explores the potential of water desalination as a proxy for energy storage systems in nuclear power plants. Various water desalination technologies are examined and compared in terms of economy, water quality and production capacity. Barakah nucle...

This paper contains a comparison of several sigma-point Kalman filters, including the unscented K... more This paper contains a comparison of several sigma-point Kalman filters, including the unscented Kalman filter (UKF), the cubature Kalman filter (CKF), and the central difference Kalman filter (CDKF). The comparison is based on a simulated electro-hydrostatic actuator, which is commonly used for flight surface actuation in aerospace systems. This brief study compares the response, convergence rate, root mean square error, the maximum absolute error, and the stability of these sigma-point Kalman filters.

Case Studies in Thermal Engineering

Abstract This work presents a case study of thermodynamic performance of a condenser used in a 21... more Abstract This work presents a case study of thermodynamic performance of a condenser used in a 210 MW thermal power station at Mejia in West Bengal, India. The analysis involves an improvement of actual overall heat transfer coefficient by varying tube materials and fouling resistance. Exergy Destruction Factor (EDF) is introduced to quantify the percentage of exergy loss from the condenser wall. From this study, it is revealed that the second law performance of the condenser increases with the increase in thermal conductivity of the tube materials, decreases with the increase in fouling resistance and decreases with the increase in condenser pressure at the turbine outlet. The actual overall heat transfer coefficient can be increased up to 6% by selecting better conducting tube materials. While the EDF decreases with the increase in cooling water temperature rise and increases with the increase in cooling water inlet temperature, EDF is found to decrease with the increased cooling water mass flow rate.

2019 Advances in Science and Engineering Technology International Conferences (ASET)

Nowadays, the application of renewable energy sources is one of the primary goals to contribute t... more Nowadays, the application of renewable energy sources is one of the primary goals to contribute to low greenhouse gas emissions and low energy cost. Geothermal energy is one of the most attractive renewable energy sources that can be exploited at low, medium and high enthalpy. Absorption chillers are cooling machines that can be powered by a low-grade geothermal energy source. The geofluid leaving the power plant can be used to provide heat for the desorber before it is reinjected to the reinjection well. In this work, a thermodynamic analysis of parallel flow double effect water/LiBr absorption chiller driven by geothermal energy is presented. The effects of many design parameters such as temperature, mass flow rate, and heat exchanger size on the coefficient of performance (COP) and cooling load are investigated. An Engineering Equation Solver (EES) is used for that purpose. The results are presented in graphical forms to show the chiller performance behavior under different operating conditions. The results show that COP and cooling load can reach about 1.43 and 420 kW for certain operating and design conditions.

Energy Engineering

The energy coming from solar radiation could be harvested and transformed into electricity throug... more The energy coming from solar radiation could be harvested and transformed into electricity through the use of solar-thermal power generation and photovoltaic (PV) power generation. Placement of solar collectors (thermal and photovoltaic) affects the amount of incoming radiation and the absorption rate. In this research, new correlations for finding the monthly optimum slope angle (OSA) on flat-plate collectors are proposed. Twelve equations are developed to calculate the monthly OSA by the linear regression model, for the northern and the southern hemisphere stations from 15°to 55°and-20°to-45°, respectively. Also, a new equation for calculating the yearly tilt angle is developed and compared with several other calculation methods from the literature. Results confirm a 20% increase in solar energy absorption by adjusting the collectors' tilt angle in monthly time periods. This is while the adjusted collectors with the yearly optimum slope angle receive approximately 7% higher solar radiation compared to the horizontal collectors. Furthermore, the proposed equations outperformed the other calculation methods in the literature.

International Journal of Mechanical Engineering Education, 1997

A thermodynamic analysis of a real waste-heat thermoelectric generator is investigated. The therm... more A thermodynamic analysis of a real waste-heat thermoelectric generator is investigated. The thermoelectric generator is considered as a heat engine cycle process with internal irreversibilities. The efficiency of the thermoelectric generator is expressed in terms of two non-dimensional parameters which are to be optimized. A finite-time thermodynamic analysis is used to optimize the temperatures of the hot and cold junctions of the real thermoelectric generator. A comparison between ideal and real waste-heat thermoelectric generators is demonstrated.

This chapter describes the fundamentals of air handling processes and equipment and answers to qu... more This chapter describes the fundamentals of air handling processes and equipment and answers to questions related to the theoretical background of air handling unit and ductwork dimensioning and building energy systems optimization. It deals with the basic air-handling processes: filtration of particles and gaseous substances from the supply and recirculated air, air heating and cooling, heat-recovery processes, and humidification and dehumidification; equipment space requirements, associated components, and the pressure losses of various components, good design practices, including system balancing and efficient running; and essential factors in the selection of systems and equipment during the design stage. On the system level, considerable efforts have been made to reduce the heating and cooling demands, and the electrical energy consumption has been regarded as a marginal part. In ductwork design, attention must be paid to reduce energy losses using properly designed fittings and proper duct sizing.

International Journal of Energy Research, 2000

A theoretical model to study the performance characteristics of a magnetohydrodynamic (MHD) power... more A theoretical model to study the performance characteristics of a magnetohydrodynamic (MHD) power plant is presented. The model takes into account the external and internal irreversibilities. General expressions for power and e$ciency of the power plant are derived when the MHD generator is operating at constant velocity and constant Mach number conditions. It is shown that when the generator and compressor are running reversibly, the constant velocity and constant Mach number cases are identical in performance and the e$ciency at maximum power is identical to Curzon}Ahlborn e$ciency. It is also shown that the constant velocity case produces less entropy generation in the generator than that of the constant Mach number case when the generator electrical e$ciency is less than one.

Case Studies in Thermal Engineering

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Computers, Materials & Continua

CO 2 emission is considerably dependent on energy consumption and on share of energy sources as w... more CO 2 emission is considerably dependent on energy consumption and on share of energy sources as well as on the extent of economic activities. Consequently, these factors must be considered for CO 2 emission prediction for seven middle eastern countries including Iran, Kuwait, United Arab Emirates, Turkey, Saudi Arabia, Iraq and Qatar. In order to propose a predictive model, a Multilayer Perceptron Artificial Neural Network (MLP ANN) is applied. Three transfer functions including logsig, tansig and radial basis functions are utilized in the hidden layer of the network. Moreover, various numbers of neurons are applied in the structure of the models. It is revealed that using MLP ANN makes it possible to accurately predict CO 2 emission of these countries. In addition, it is concluded that using logsig transfer function leads to the highest accuracy with minimum value of mean squared error (MSE) which is followed by the networks with radial basis and tansig transfer functions. The R-squared of the networks with logsig, radial basis and tansig transfer functions are 0.9998, 0.9997 and 0.9996, respectively. Finally, comparison of the proposed model with a similar study, considered five countries in the same region, reveals higher accuracy in term of MSE.

Nanofluid is mixture between nanoparticle and base fluid, this mixture is used to enhance the hea... more Nanofluid is mixture between nanoparticle and base fluid, this mixture is used to enhance the heat transfer process inside heat exchangers. In this work, three alternatives of nanofluid based on CuO and TiO2 were studied inside concentric tube heat exchanger. Different volume fractions (0.05 % and 0.2 %) and mass flow rates (0.05 kg/sec and 0.25 kg/sec) were tested. 3-D numerical simulation was performed using computational fluid dynamic (CFD) for all nanofluid types under the same volume fraction (0.2 %). The numerical results showed that CuO nanofluid has the highest enhancement heat transfer ratio among the others two types where these augmentation ratios were 47% and 61 % for TiO2 and CuO respectively, while experimental results showed that these augmentation ratios were 48% and 50 % for TiO2, and CuO respectively at volume fraction 0.05 % and 30% and 62% for TiO2 and CuO respectively at volume fraction 0.2 %.

The depletion of fossil fuel energy resources, increasing concern of air pollution, global warmin... more The depletion of fossil fuel energy resources, increasing concern of air pollution, global warming and energy crisis have encouraged the research to develop innovative alternatives in engineering systems. This work presents a problem of minimizing the life cycle cost (as an economic criterion) of an air conditioning system for vapor compression and maximizing the useful heat (as a thermodynamic criterion). The mathematical model that represents the objective function has four decision variables: evaporation temperature and condensation temperature of the refrigerant, and volumetric flow rate of air in the condenser and the evaporator. The problem is a global optimization and the search method of solution is genetic algorithm. A thermodynamic model included design of exchanger. The methodology used is for R-1234yf, a low GWP refrigerant, which is R-134a refrigerant substitute.

The solar power tower system (SPTS) has been successfully demonstrated as a favorable candidates ... more The solar power tower system (SPTS) has been successfully demonstrated as a favorable candidates to replace fossil fuel energy systems. Although several investigations have been developed to assess the SPTS, the detailed, fundamentals-based, long-term transient simulation capability is limited. Research presented in this chapter is intended to indicate how artificial intelligence (AI) techniques may play an important role to address this need. For this purpose, a method of AI is developed to simulate a solar power tower direct steam (SPTDS) system. As a matter of fact, this hybrid method is developed through the combination of adaptive neurofuzzy inference system with biogeography-based optimization algorithm. The power losses from the receiver, power absorbed by the receiver, receiver thermal efficiency, field optical focus fraction, field optical efficiency, and the cycle electrical power output are simulated and appraised through the intelligent method. A set of input parameters ...

Procceedings of the 18th Brazilian Congress of Thermal Sciences and Engineering