Amirkabir University of Technology Amirkabir Journal of Mechanical Engineering 2008-6032 53 1 2021 03 21 Effect of Start of Injection Timing on Waste Heat Recovery Capacity in a Reactivity Controlled Compression Ignition Engine Effect of Start of Injection Timing on Waste Heat Recovery Capacity in a Reactivity Controlled Compression Ignition Engine 3 16 3415 10.22060/mej.2019.15465.6128 FA Mehrdad Nazemian Department of Mechanical Engineering, Sahand University of Technology, Sahand New Town, Tabriz, Iran Elahe Neshat Department of Mechanical Engineering, Sahand University of Technology, Sahand New Town, Tabriz, Iran Rahim Khoshbakhti Saray Department of Mechanical Engineering, Sahand University of Technology, Sahand New Town, Tabriz, Iran Journal Article 2018 12 17 It is noteworthy that about one-third of the input energy to the cylinder of an internal combustion engine becomes useful work and the rest of the energy is lost by various factors. Therefore, providing solutions that can recover waste heat is remarkable and useful. In the current study, the effect of the start of injection timing on the reactivity controlled compression ignition engine on the waste heat recovery capacity has been investigated. After verifying the results, diesel fuel start of injection timing has been changed and their effects on exergy destruction, waste heat recovery capacity, power output and emissions have been investigated. The results showed that the advanced start of injection timing increases engine efficiency and decreases carbon monoxide and unburned hydrocarbons emissions. In addition, heat transfer exergy has increased due to the higher in cylinder temperature, and the higher temperature has led to an increase in irreversibility due to the increased number of reactions. Advanced fuel injection timing has improved utilization. It is noteworthy that about one-third of the input energy to the cylinder of an internal combustion engine becomes useful work and the rest of the energy is lost by various factors. Therefore, providing solutions that can recover waste heat is remarkable and useful. In the current study, the effect of the start of injection timing on the reactivity controlled compression ignition engine on the waste heat recovery capacity has been investigated. After verifying the results, diesel fuel start of injection timing has been changed and their effects on exergy destruction, waste heat recovery capacity, power output and emissions have been investigated. The results showed that the advanced start of injection timing increases engine efficiency and decreases carbon monoxide and unburned hydrocarbons emissions. In addition, heat transfer exergy has increased due to the higher in cylinder temperature, and the higher temperature has led to an increase in irreversibility due to the increased number of reactions. Advanced fuel injection timing has improved utilization.

https://mej.aut.ac.ir/article_3415_f6d9e459b9fbf6dd26c4f7d621adec1d.pdf

Amirkabir University of Technology Amirkabir Journal of Mechanical Engineering 2008-6032 53 1 2021 03 21 Investigation of Performance and Emission Characteristic of a Reactivity Controlled Compression Ignition Engine Fueled By a Mixture of Diesel and Syngas Derived From Biomass Gasification Investigation of Performance and Emission Characteristic of a Reactivity Controlled Compression Ignition Engine Fueled By a Mixture of Diesel and Syngas Derived From Biomass Gasification 17 30 3618 10.22060/mej.2019.15909.6228 FA Navid Kousheshi University of Bonab Mortaza Yari University of Tabriz Ali Saberi Mehr بناب-فنی و مهندسی- مهندسی مکانیک Journal Article 2019 03 04 Recently, low-temperature combustion methods have become very popular in the field of combustion. Reactivity controlled compression ignition is a novel combustion concept with its own advantages. The role of these engines in rectifying the disadvantages of other methods is inevitable. This paper studies the influence of using various types of syngas on combustion and emission characteristics of syngas/diesel reactivity controlled compression ignition engine using Converge CFD. Four types of syngas (ideal syngas composed of solely hydrogen and carbon monoxide, two different types of syngases produced by gasifiers and pure hydrogen) are selected for comparison. Results showed the possibility of using various forms of syngases as low reactivity fuel. Using these kinds of syngases compared with ideal one results in fewer nitrogen oxides at the expense of more soot and it gets worse by increasing the fraction of syngas in premixed air. It shouldn’t be ignored, due to the presence of nitrogen in some types, the engine may suffer from weak combustion and sometimes misfire at low loads as well. Using pure hydrogen, despite its advantages as the main part of syngas, in high quantities, notwithstanding the significant reduction of soot, causes the increase of nitrogen oxides and pressure rise rate amounts which are not desirable. Recently, low-temperature combustion methods have become very popular in the field of combustion. Reactivity controlled compression ignition is a novel combustion concept with its own advantages. The role of these engines in rectifying the disadvantages of other methods is inevitable. This paper studies the influence of using various types of syngas on combustion and emission characteristics of syngas/diesel reactivity controlled compression ignition engine using Converge CFD. Four types of syngas (ideal syngas composed of solely hydrogen and carbon monoxide, two different types of syngases produced by gasifiers and pure hydrogen) are selected for comparison. Results showed the possibility of using various forms of syngases as low reactivity fuel. Using these kinds of syngases compared with ideal one results in fewer nitrogen oxides at the expense of more soot and it gets worse by increasing the fraction of syngas in premixed air. It shouldn’t be ignored, due to the presence of nitrogen in some types, the engine may suffer from weak combustion and sometimes misfire at low loads as well. Using pure hydrogen, despite its advantages as the main part of syngas, in high quantities, notwithstanding the significant reduction of soot, causes the increase of nitrogen oxides and pressure rise rate amounts which are not desirable.

https://mej.aut.ac.ir/article_3618_4da9d7b6d119db4d2d564a2197798380.pdf

Amirkabir University of Technology Amirkabir Journal of Mechanical Engineering 2008-6032 53 1 2021 03 21 Experimental Study of Injecting Water Vapor and Oil Compounds by Nebulizer on the Efficiency and Natural Gas Flame Pollution Experimental Study of Injecting Water Vapor and Oil Compounds by Nebulizer on the Efficiency and Natural Gas Flame Pollution 31 40 3584 10.22060/mej.2019.16049.6262 FA Amin Jodat Mechanical Engineering Department, University of Bojnord, Bojnord 945 3155111, Iran. Mojtaba Najafian Mechanical Engineering, Applied Science University of North Khorasan, Bojnord, Iran. Abolfazl Mohammadi Chemical Engineering Department, University of Bojnord, Bojnord 945 3155111, Iran. Journal Article 2019 03 27 In this study, by using nebulizer technology commonly used for the delivery of aerosolized drugs in pulmonary patients, the effect of injecting oil compounds and water vapor by nebulizer on the thermal efficiency and production of pollutants in gas emissions of natural gas diffusion flame is studied. The Nebulizer device creates micron incisions of injected liquid and, due to the reduced injection particle diameter, existing highly turbulent outflow and proper mixing of oil and water vapor compounds with gas and air inlet to the burner, effectiveness of the injection increases to enhance efficiency and reduce pollutants. In the experimental setup, the injection of 1 wt% of oil compounds into the natural gas flame by a nebulizer improves thermal efficiency by 2.5%, decreases the temperature of the exhaust gases from the chimney by 12%, and also pollutants by 13%, and increases carbon monoxide pollutant by 6%. Also, the injection of 2 wt.% of water drops as well as 1 wt.% of oil compounds will increase thermal efficiency by more than 1%, reduce the temperature of chimney exhaust gases by 6 %, reduce pollutants by more than 42 % and carbon monoxide pollutant by 26%. In this study, by using nebulizer technology commonly used for the delivery of aerosolized drugs in pulmonary patients, the effect of injecting oil compounds and water vapor by nebulizer on the thermal efficiency and production of pollutants in gas emissions of natural gas diffusion flame is studied. The Nebulizer device creates micron incisions of injected liquid and, due to the reduced injection particle diameter, existing highly turbulent outflow and proper mixing of oil and water vapor compounds with gas and air inlet to the burner, effectiveness of the injection increases to enhance efficiency and reduce pollutants. In the experimental setup, the injection of 1 wt% of oil compounds into the natural gas flame by a nebulizer improves thermal efficiency by 2.5%, decreases the temperature of the exhaust gases from the chimney by 12%, and also pollutants by 13%, and increases carbon monoxide pollutant by 6%. Also, the injection of 2 wt.% of water drops as well as 1 wt.% of oil compounds will increase thermal efficiency by more than 1%, reduce the temperature of chimney exhaust gases by 6 %, reduce pollutants by more than 42 % and carbon monoxide pollutant by 26%.

https://mej.aut.ac.ir/article_3584_565767eb96d87d0d3af8dfb332c2003f.pdf

Amirkabir University of Technology Amirkabir Journal of Mechanical Engineering 2008-6032 53 1 2021 03 21 Experimental Investigation of Combustion Species Radiation to Evaluate Equivalence Ratio in a Surface Flame Burner Experimental Investigation of Combustion Species Radiation to Evaluate Equivalence Ratio in a Surface Flame Burner 41 52 3629 10.22060/mej.2019.16162.6290 FA Hossein Soltanian Department of mechanical engineering, Tarbiat Modares University, Tehran, Iran Mohammad Zabetian Toroghi تربیت مدرس-مهندسی مکانیک Hadi Pasdarshahri Department of mechanical engineering, Tabiat Modares University, Tehran, Iran Journal Article 2019 04 18 In the present research, combustion species were investigated in perforated natural gas burner based on flame emission spectroscopy. An experimental investigation is performed on a new burner test rig which is one of the most popular burners used in condensation boilers through a spectrometer-fiber optic to get the flame emission of a perforated burner. Combustion species H2O*, OH*, CH*, C2* and CO2* are detected from their chemiluminescence The emission of CO2* which has the main role in heat release rate of burner was investigated for different equivalence ratios (Φ) and burner powers of 11-16 kW showing an intensity peak in the range of Φ between 0.78 to 0.85 that corresponds to the maximum heat release rate. Emission of OH* was also investigated being the main indicator of NO regarding its producing mechanism. Its maximum was found at the range of at Φ=0.78 to 0.85 for different burner powers. A similar experiment showed that OH*/CH* intensity ratio was independent of burner power as is confirmed by previous researchers. One could infer the equivalence ratio from the flame emission. In the present research, combustion species were investigated in perforated natural gas burner based on flame emission spectroscopy. An experimental investigation is performed on a new burner test rig which is one of the most popular burners used in condensation boilers through a spectrometer-fiber optic to get the flame emission of a perforated burner. Combustion species H2O*, OH*, CH*, C2* and CO2* are detected from their chemiluminescence The emission of CO2* which has the main role in heat release rate of burner was investigated for different equivalence ratios (Φ) and burner powers of 11-16 kW showing an intensity peak in the range of Φ between 0.78 to 0.85 that corresponds to the maximum heat release rate. Emission of OH* was also investigated being the main indicator of NO regarding its producing mechanism. Its maximum was found at the range of at Φ=0.78 to 0.85 for different burner powers. A similar experiment showed that OH*/CH* intensity ratio was independent of burner power as is confirmed by previous researchers. One could infer the equivalence ratio from the flame emission.

https://mej.aut.ac.ir/article_3629_1305f6c705349316360c3ccfe7cfe847.pdf

Amirkabir University of Technology Amirkabir Journal of Mechanical Engineering 2008-6032 53 1 2021 03 21 One-dimensional Combustion Simulation for Different Hydrogen-enriched Natural Gas Blends One-dimensional Combustion Simulation for Different Hydrogen-enriched Natural Gas Blends 53 64 3477 10.22060/mej.2019.15240.6071 FA Ehsan Bahmani Department of Mechanical Engineering, Engineering Faculty, Tarbiat Modares University, Tehran, Iran 0000-0002-9027-0228 Kiumars Mazaheri Department of Mechanical Engineering, Engineering Faculty, Tarbiat Modares University, Tehran, Iran Alireza Alipour شهید چمران اهواز-مهندسی- گروه مهندسی مکانیک Journal Article 2018 11 03 Land-based gas turbines are one of the most practical turbines that use natural gas as the main fuel. Since natural gas is produced with different compositions in the refinery process, it can lead to change widely the combustion characteristics. In order to avoid this undesirable variation on combustion characteristics, different methods are suggested. One of these methods is the injection of Hydrogen into the main fuel (i.e. Natural gas). Hydrogen fuel has some desirable properties such as low activation energy, high reaction rate and high burning velocity which makes hydrogen as a suitable additive for modification of combustion characteristics of hydrocarbon fuels. The main purpose of the present study is studying the effects of Hydrogen addition into the different compositions of natural gas to achieve better combustion characteristics. It is observed that the addition of Hydrogen in a specific volumetric percentage into main fuel causes to modify combustion properties, for instance increasing flammability limits. Land-based gas turbines are one of the most practical turbines that use natural gas as the main fuel. Since natural gas is produced with different compositions in the refinery process, it can lead to change widely the combustion characteristics. In order to avoid this undesirable variation on combustion characteristics, different methods are suggested. One of these methods is the injection of Hydrogen into the main fuel (i.e. Natural gas). Hydrogen fuel has some desirable properties such as low activation energy, high reaction rate and high burning velocity which makes hydrogen as a suitable additive for modification of combustion characteristics of hydrocarbon fuels. The main purpose of the present study is studying the effects of Hydrogen addition into the different compositions of natural gas to achieve better combustion characteristics. It is observed that the addition of Hydrogen in a specific volumetric percentage into main fuel causes to modify combustion properties, for instance increasing flammability limits.

https://mej.aut.ac.ir/article_3477_6d6968d87c240c699190e2d8c029fa9d.pdf

Amirkabir University of Technology Amirkabir Journal of Mechanical Engineering 2008-6032 53 1 2021 03 21 Evaluation of Combustion Models in a Porous Medium with Different Excess Air Ratios Evaluation of Combustion Models in a Porous Medium with Different Excess Air Ratios 65 80 3407 10.22060/mej.2019.15713.6187 FA Hossein Ajam Iman Mohammadi mechanical engineering ferdowsi university of mashhad Journal Article 2019 01 28 In this paper, the simultaneous study of the effects of the excess air ratio and the combustion mechanisms on the temperature and distribution of species in the porous medium burners with continuous porosity variation has been investigated. For this purpose, multi-step chemical kinetics have been used and their effects on the temperature profile, mass fraction of the main species and emission of pollutants for different values of the excess air ratio have been investigated. Problem-solving equations include continuity equation, momentum equations, gas, and solid phase energy equations, and the chemical equilibrium equation is solved using the finite volume method and the semi-implicit method for pressure linked equations algorithm is used for the relationship between velocity and pressure. The results showed that for excess air ratio of 1.5, the results of combustion mechanisms have the same accuracy in predicting the temperature profile and mass fraction of the main species, and then, for additional values of the excess air ratio, the results of the combustion mechanisms Show a slight difference. This is while the greatest difference in the results is observed for the stoichiometric condition. Also in stoichiometric conditions, the NO emission rate using the GRI-3.0 combustion mechanism is predicted to be zero, and for the rest of the coefficients of the excess air ratio, its value will be of the order of magnitude 10-6. In this paper, the simultaneous study of the effects of the excess air ratio and the combustion mechanisms on the temperature and distribution of species in the porous medium burners with continuous porosity variation has been investigated. For this purpose, multi-step chemical kinetics have been used and their effects on the temperature profile, mass fraction of the main species and emission of pollutants for different values of the excess air ratio have been investigated. Problem-solving equations include continuity equation, momentum equations, gas, and solid phase energy equations, and the chemical equilibrium equation is solved using the finite volume method and the semi-implicit method for pressure linked equations algorithm is used for the relationship between velocity and pressure. The results showed that for excess air ratio of 1.5, the results of combustion mechanisms have the same accuracy in predicting the temperature profile and mass fraction of the main species, and then, for additional values of the excess air ratio, the results of the combustion mechanisms Show a slight difference. This is while the greatest difference in the results is observed for the stoichiometric condition. Also in stoichiometric conditions, the NO emission rate using the GRI-3.0 combustion mechanism is predicted to be zero, and for the rest of the coefficients of the excess air ratio, its value will be of the order of magnitude 10-6.

https://mej.aut.ac.ir/article_3407_dab49080d80c724aad5ebf158d63df41.pdf

Amirkabir University of Technology Amirkabir Journal of Mechanical Engineering 2008-6032 53 1 2021 03 21 Techno-Economic Feasibility of Energy Supply Systems from Renewable Sources of Solar and Biomass in Rural Areas Located In Cold and Dry Climate Techno-Economic Feasibility of Energy Supply Systems from Renewable Sources of Solar and Biomass in Rural Areas Located In Cold and Dry Climate 81 100 3594 10.22060/mej.2019.16153.6287 FA Maryam Sadat Alaeipour Department of Mechanical Engineering, Imam Khomeini International University Mostafa Mafi Department of Mechanical Engineering / Imam Khomeini International University Mansour Khanaki Imam Khomeini International University Masood Ebrahimi Department of Mechanical Engineering, Kurdistan University Journal Article 2019 04 18 The present work focuses on the feasibility study of locally available renewable energy production systems for mountainous rural areas with cold and dry climates (including solar systems and biomass resulted from manure dung). The studied rural area consists of three cold and impassable villages of Pichebon, Narmelat, and Dinheroud, located in Eastern Alamut of Qazvin. Three scenarios have been presented and related techno-economic analyses have been done. Firstly, all heating needs and electricity demands have been met solely by the photovoltaic system. In the second scenario, heating and electricity needs have been supplied by biogas and combined heat and power system. Moreover, the heat loss of the motor has been used to warm up the digester. In the last survey, the electricity need has been supplied by the photovoltaic system along with covering heating demand through biogas. In this scenario, the required heat to operate digester is provided using the photovoltaic system. The results show that the second scenario that has a positive Net Present Value in each discount rate (5%, 10% and 15%) and Internal Rate of Return is 24.24% 23.26% and 38.6% for Pichebon, Narmelat and Dinehroud villages, respectively, is as practical design and economic option. The present work focuses on the feasibility study of locally available renewable energy production systems for mountainous rural areas with cold and dry climates (including solar systems and biomass resulted from manure dung). The studied rural area consists of three cold and impassable villages of Pichebon, Narmelat, and Dinheroud, located in Eastern Alamut of Qazvin. Three scenarios have been presented and related techno-economic analyses have been done. Firstly, all heating needs and electricity demands have been met solely by the photovoltaic system. In the second scenario, heating and electricity needs have been supplied by biogas and combined heat and power system. Moreover, the heat loss of the motor has been used to warm up the digester. In the last survey, the electricity need has been supplied by the photovoltaic system along with covering heating demand through biogas. In this scenario, the required heat to operate digester is provided using the photovoltaic system. The results show that the second scenario that has a positive Net Present Value in each discount rate (5%, 10% and 15%) and Internal Rate of Return is 24.24% 23.26% and 38.6% for Pichebon, Narmelat and Dinehroud villages, respectively, is as practical design and economic option.

https://mej.aut.ac.ir/article_3594_dce8af15f064d1accb98887a21029b08.pdf

Amirkabir University of Technology Amirkabir Journal of Mechanical Engineering 2008-6032 53 1 2021 03 21 Numerical and Experimental Modal Analysis of a 400 W Polymer Electrolyte Membrane Fuel Cell Numerical and Experimental Modal Analysis of a 400 W Polymer Electrolyte Membrane Fuel Cell 101 116 3538 10.22060/mej.2019.15878.6216 FA Mohammad Mahdi Mohammadi Fuel cell Technology Research laboratory, Malek Ashtar University of Technology Mohammad Mahdi Barzegari Fuel cell Technology Research laboratory, Malek Ashtar University of Technology Journal Article 2019 02 25 With the increasing utilization of polymer electrolyte membrane fuel cells in cars, ships, and airplanes, the study of vibrational behavior of fuel cells has gained particular importance. In this paper, a modal analysis of 400-Watt 4-cells fuel cell with an active surface area of 225 has been performed numerically and experimentally. The time domain method has been used to extract global fuel cell frequencies. By interpreting the output data of the sensors and using the phase response angle, two natural frequencies of the model were extracted. The results of the test showed that the first transverse and longitudinal frequency of the model is 500 Hz and about 2500 Hz, respectively. Then, the simulation of the finite element model was studied in detail. A comparison of the frequencies obtained from the test and numerical analysis showed that the maximum difference is about 8%. Therefore, numerical analysis of the model with sufficient detail can adequately cover the vibrational properties of the real model. Also, the results showed that by changing the geometrical and mechanical properties of the membrane by 45%, the natural frequency of fuel cell changes through 4%. Furthermore, removing the membrane plates, in addition to reducing the number of model elements, reduces the contact constraints. With the increasing utilization of polymer electrolyte membrane fuel cells in cars, ships, and airplanes, the study of vibrational behavior of fuel cells has gained particular importance. In this paper, a modal analysis of 400-Watt 4-cells fuel cell with an active surface area of 225 has been performed numerically and experimentally. The time domain method has been used to extract global fuel cell frequencies. By interpreting the output data of the sensors and using the phase response angle, two natural frequencies of the model were extracted. The results of the test showed that the first transverse and longitudinal frequency of the model is 500 Hz and about 2500 Hz, respectively. Then, the simulation of the finite element model was studied in detail. A comparison of the frequencies obtained from the test and numerical analysis showed that the maximum difference is about 8%. Therefore, numerical analysis of the model with sufficient detail can adequately cover the vibrational properties of the real model. Also, the results showed that by changing the geometrical and mechanical properties of the membrane by 45%, the natural frequency of fuel cell changes through 4%. Furthermore, removing the membrane plates, in addition to reducing the number of model elements, reduces the contact constraints.

https://mej.aut.ac.ir/article_3538_1458e7509aa5f47ecfb92536e7dd1dc7.pdf

Amirkabir University of Technology Amirkabir Journal of Mechanical Engineering 2008-6032 53 1 2021 03 21 Simulation and Optimization of Rankine Power Generation Cycle Purposing the Efficiency of Liquefied Natural Gas Cold Exergy Simulation and Optimization of Rankine Power Generation Cycle Purposing the Efficiency of Liquefied Natural Gas Cold Exergy 117 134 3400 10.22060/mej.2019.15583.6161 FA Alireza Sadeghi Imam Khomeini international university, Qazvin, Iran Mohsen Kashi Parpinchi Imam Khomeini international university, Qazvin, Iran Seyed Abbas Sadatsakak Imam Khomeini International University Mansour Khanaki Imam Khomeini International University Journal Article 2019 01 05 Liquefied natural gas is obtained by cooling the natural gas to −162℃ at the atmospheric pressure. Methane is the major chemical component of liquefied natural gas which varies between 87.0–99.8% for different sources. The cryogenic power generation cycle using liquefied natural gas as its heat sink is known to be one of the considerable ways for the liquefied natural gas exergy recovery. A double-stage Rankine power generation cycle using the single component working fluid in each stage for liquefied natural gas cold exergy recovery is used as a base case in the present study. To improve the recovery of liquefied natural gas cold exergy, a three-stage Rankine power generation cycle has been proposed using mixture working fluid. Optimization is done using the particle swarm algorithm. The performance of the three-stage Rankine power generation cycle is studied regarding the effects of thermal efficiencies, exergy efficiencies, overall heat transfer coefficient of condensers and natural gas distribution pressure. Specific power production of the cycle is 100.45, thermal efficiency is 12.76%, and exergy efficiency is 27.92%. By decreasing the total coefficient of heat transfer, the condensers of different stages of the cycle reduce the maximum output power of the cycle with different trends. The results show that by decreasing the distribution pressure of natural gas, specific power production, thermal efficiency and exergy efficiency increases. So that their optimal values at 6 bar are 290.87, 25.63% and 39.12%, respectively. Liquefied natural gas is obtained by cooling the natural gas to −162℃ at the atmospheric pressure. Methane is the major chemical component of liquefied natural gas which varies between 87.0–99.8% for different sources. The cryogenic power generation cycle using liquefied natural gas as its heat sink is known to be one of the considerable ways for the liquefied natural gas exergy recovery. A double-stage Rankine power generation cycle using the single component working fluid in each stage for liquefied natural gas cold exergy recovery is used as a base case in the present study. To improve the recovery of liquefied natural gas cold exergy, a three-stage Rankine power generation cycle has been proposed using mixture working fluid. Optimization is done using the particle swarm algorithm. The performance of the three-stage Rankine power generation cycle is studied regarding the effects of thermal efficiencies, exergy efficiencies, overall heat transfer coefficient of condensers and natural gas distribution pressure. Specific power production of the cycle is 100.45, thermal efficiency is 12.76%, and exergy efficiency is 27.92%. By decreasing the total coefficient of heat transfer, the condensers of different stages of the cycle reduce the maximum output power of the cycle with different trends. The results show that by decreasing the distribution pressure of natural gas, specific power production, thermal efficiency and exergy efficiency increases. So that their optimal values at 6 bar are 290.87, 25.63% and 39.12%, respectively.

https://mej.aut.ac.ir/article_3400_e945de21a1bb5714a0bc8a897ed32e9f.pdf

Amirkabir University of Technology Amirkabir Journal of Mechanical Engineering 2008-6032 53 1 2021 03 21 Thermodynamic Analysis of a Novel Power, Cooling, Hydrogen and Oxygen Multi-Generation Combined Cycle Based on the Sabalan Geothermal Wells Thermodynamic Analysis of a Novel Power, Cooling, Hydrogen and Oxygen Multi-Generation Combined Cycle Based on the Sabalan Geothermal Wells 135 154 3369 10.22060/mej.2019.15500.6138 FA Mehran Abdolalipouradl Mechanical Engineering Department, Faculty of engineering, Urmia University, Urmia, Iran Shahram Khalilarya 0000-0002-6434-852X Farzad Mohammadkhani Department of Mechanical Engineering, Mechanical Engineering Faculty, University of Tabriz, Tabriz, Iran 0000-0003-3399-3099 Journal Article 2018 12 22 The use of multi-generation systems is rapidly developing in the world. Although Sabalan geothermal field is one of the important geothermal fields of Iran, the possibility of using the multi-generation systems has not yet been performed. As an attempt to fulfill the gap in the field, a new cooling, hydrogen, oxygen, and power multi-generation cycle for using Sabalan geothermal wells is proposed and analyzed. In the proposed system, the double flash configuration from the Sabalan geothermal wells as the heat source is used. An organic Rankine cycle is used to generate power for the proton exchange membrane for hydrogen production and a LiBr-H2O absorption refrigeration system is used for cooling production. First, a simulation was done by Engineering Equation Solver software and then the effects of some design parameters, such as separators pressures, evaporator temperature, pinch point temperature difference in the Rankine evaporator, generator temperature and ambient temperature on the integrated system performance are studied. A parametric study shows that the value of the thermal efficiency and cooling continuously increases with separators' pressures. According to the results, the value of the net output power, hydrogen production, cooling and thermal and exergy efficiencies of the cogeneration system are obtained as 14739 kW, 13.25 kg/hr, 10925 kW, 22.34% and 50.62% respectively. The use of multi-generation systems is rapidly developing in the world. Although Sabalan geothermal field is one of the important geothermal fields of Iran, the possibility of using the multi-generation systems has not yet been performed. As an attempt to fulfill the gap in the field, a new cooling, hydrogen, oxygen, and power multi-generation cycle for using Sabalan geothermal wells is proposed and analyzed. In the proposed system, the double flash configuration from the Sabalan geothermal wells as the heat source is used. An organic Rankine cycle is used to generate power for the proton exchange membrane for hydrogen production and a LiBr-H2O absorption refrigeration system is used for cooling production. First, a simulation was done by Engineering Equation Solver software and then the effects of some design parameters, such as separators pressures, evaporator temperature, pinch point temperature difference in the Rankine evaporator, generator temperature and ambient temperature on the integrated system performance are studied. A parametric study shows that the value of the thermal efficiency and cooling continuously increases with separators' pressures. According to the results, the value of the net output power, hydrogen production, cooling and thermal and exergy efficiencies of the cogeneration system are obtained as 14739 kW, 13.25 kg/hr, 10925 kW, 22.34% and 50.62% respectively.

https://mej.aut.ac.ir/article_3369_dda99de58ff020cfb57fec1404c97003.pdf

Amirkabir University of Technology Amirkabir Journal of Mechanical Engineering 2008-6032 53 1 2021 03 21 The Feasibility Study of a Night Sky Radiative Cooling System for Cooling the Intake Air of a Gas Turbine The Feasibility Study of a Night Sky Radiative Cooling System for Cooling the Intake Air of a Gas Turbine 155 172 3492 10.22060/mej.2019.15461.6127 FA Mohammad Reza Sangtarash Mechanical engineering department- Engineering faculty- Unversity of Sistan and Balouchestan- Zahedan- Iran Said Farahat Mechanical engineering department- Engineering faculty- Unversity of Sistan and Balouchestan- Zahedan- Iran Mostafa Dehghani Mohammadabadi Mechanical engineering department- Engineering faculty- Unversity of Sistan and Balouchestan- Zahedan- Iran 0000-0003-2888-8411 Journal Article 2018 12 17 The compressor inlet air cooling, especially in hot climates, has a significant effect on the power output augmentation of the gas turbines. The water consumption in evaporative cooling and fogging systems and power consumption and investment cost in vapor absorption and compression refrigeration systems are high. So, the purpose of this article is to investigate the possibility of using the night sky radiative cooling system for cooling the intake air of the compressor. In this method, the circulating water used to cool the intake air of the compressor, at night and in the exchange of radiation with the sky, is cooled using glassless flat plate collectors and returns to the storage tank for reuse on the next day. The effect of parameters such as the number and arrangement of collectors in series or parallel on the cooling capacity is investigated. Also, the required storage tank volume for returned water from collectors is calculated. The results show that the compressor’s intake air cooling for six hours a day needs a storage tank with a minimum capacity of 1000 m3. Also, by using 400 parallel collectors and a 1000 m3 storage tank, the power production increases by an average of 2 MWh. The compressor inlet air cooling, especially in hot climates, has a significant effect on the power output augmentation of the gas turbines. The water consumption in evaporative cooling and fogging systems and power consumption and investment cost in vapor absorption and compression refrigeration systems are high. So, the purpose of this article is to investigate the possibility of using the night sky radiative cooling system for cooling the intake air of the compressor. In this method, the circulating water used to cool the intake air of the compressor, at night and in the exchange of radiation with the sky, is cooled using glassless flat plate collectors and returns to the storage tank for reuse on the next day. The effect of parameters such as the number and arrangement of collectors in series or parallel on the cooling capacity is investigated. Also, the required storage tank volume for returned water from collectors is calculated. The results show that the compressor’s intake air cooling for six hours a day needs a storage tank with a minimum capacity of 1000 m3. Also, by using 400 parallel collectors and a 1000 m3 storage tank, the power production increases by an average of 2 MWh.

https://mej.aut.ac.ir/article_3492_0060ef47b12160b9198302ebdb144dcf.pdf

Amirkabir University of Technology Amirkabir Journal of Mechanical Engineering 2008-6032 53 1 2021 03 21 Thermal Analysis of a Solar Wall Equipped with Photovoltaic Cells and Phase-Change Materials Thermal Analysis of a Solar Wall Equipped with Photovoltaic Cells and Phase-Change Materials 173 190 3641 10.22060/mej.2019.16268.6315 FA Nahid Azadi Masters student, Department of Mechanical Engineering, Sistan and Baluchestan University, Iran Faramarz Sarhaddi Head of Department of Mechanical Engineering Research Laboratory of Renewable Energies and Electromagnetic Fluids, Department of Mechanical Engineering, University of Sistan and Baluchestan, Zahedan, Iran 0000-0002-5216-9823 Fatemeh Sobhnamayan Department of Mechanical Engineering, University of Sistan and Baluchestan, Zahedan, Iran Journal Article 2019 05 04 In this paper, the thermal analysis of a solar wall system equipped with photovoltaic cells and phase-change materials has been numerically investigated. For the thermal modeling of the system, the energy balance for its various components, including photovoltaic cells, air channel, absorber plate, phase-change material, and room are written. The validation of the numerical results is consistent with the experimental data of previous studies. In parametric studies, the effect of phase-change material thickness, inlet air flow rate, collector width, and packing factor have been investigated on the room temperature and system average energy efficiency in four consecutive days. Results show that the optimal phase-change material thickness is 0.05 m. Increasing the phase-change material thickness reduces the room temperature and energy efficiency. Increasing the airflow rate decreases the photovoltaic cell temperature and increases electrical efficiency, thereby increasing energy efficiency. However, it reduces room temperature. Therefore, the optimum flow rate of air was obtained at 0.04 kg/s. Increasing the collector width, despite increasing room temperature, reduces energy efficiency, so the optimum collector width was 0.7 m. The increase of the packing factor increases room temperature and reduces energy efficiency. Therefore, the optimum packing factor was 0.5. In this paper, the thermal analysis of a solar wall system equipped with photovoltaic cells and phase-change materials has been numerically investigated. For the thermal modeling of the system, the energy balance for its various components, including photovoltaic cells, air channel, absorber plate, phase-change material, and room are written. The validation of the numerical results is consistent with the experimental data of previous studies. In parametric studies, the effect of phase-change material thickness, inlet air flow rate, collector width, and packing factor have been investigated on the room temperature and system average energy efficiency in four consecutive days. Results show that the optimal phase-change material thickness is 0.05 m. Increasing the phase-change material thickness reduces the room temperature and energy efficiency. Increasing the airflow rate decreases the photovoltaic cell temperature and increases electrical efficiency, thereby increasing energy efficiency. However, it reduces room temperature. Therefore, the optimum flow rate of air was obtained at 0.04 kg/s. Increasing the collector width, despite increasing room temperature, reduces energy efficiency, so the optimum collector width was 0.7 m. The increase of the packing factor increases room temperature and reduces energy efficiency. Therefore, the optimum packing factor was 0.5.

https://mej.aut.ac.ir/article_3641_22c5a901070d1c2ad33e821d071ae97e.pdf

Amirkabir University of Technology Amirkabir Journal of Mechanical Engineering 2008-6032 53 1 2021 03 21 Effect of Air Curtain on Occupants Thermal Comfort and Indoor Air Quality in an Athletic Swimming Pool with Spectators’ Stand Effect of Air Curtain on Occupants Thermal Comfort and Indoor Air Quality in an Athletic Swimming Pool with Spectators’ Stand 191 208 3193 10.22060/mej.2018.14584.5892 FA Alireza Zolfaghari University of Birjand 0000-0001-9917-3400 Saeed Azizi University of Birjand Seyed Mohammad Hooshmand University of Birjand Journal Article 2018 06 10 In swimming pools with spectators’ stand, due to differences in skin wetness, metabolic rates and clothing type of the swimmers and spectators, providing thermal comfort conditions for all residents is very difficult. Accordingly, using the air curtain to aerodynamically separate the pool hall and the spectators’ stand is a reasonable idea to provide the mentioned different thermal comfort conditions. In the mentioned conditions, it is possible to use two different ventilation systems for these two parts. In the present study, an Olympic-size swimming pool with the spectators’ stand is modeled and distribution of velocity, temperature, relative humidity, and chlorine concentration have been determined. Also, the results have been analyzed in both cases: using air curtain and without air curtain. The results show that the air curtain can significantly reduce the influence of chlorine pollutants on the spectators' section, so the concentration of chlorine at spectators’ stand with the air curtain is about 0.00016 mg/m3 less than the case without air curtain. In this study, 65 multi node local thermal comfort model has been used to determine the thermal comfort of individuals. In the case of using the air curtain, the standard deviation of thermal comfort index for first to third rows are 0.26, 0.25, and 0.28 respectively; and in the absence of air curtain, for first to third rows the standard deviation of thermal comfort index are 0.33, 0.39 and 0.35, respectively. These results indicate that using the air curtain can lead the thermal sensation to be more favorable and more uniform. In swimming pools with spectators’ stand, due to differences in skin wetness, metabolic rates and clothing type of the swimmers and spectators, providing thermal comfort conditions for all residents is very difficult. Accordingly, using the air curtain to aerodynamically separate the pool hall and the spectators’ stand is a reasonable idea to provide the mentioned different thermal comfort conditions. In the mentioned conditions, it is possible to use two different ventilation systems for these two parts. In the present study, an Olympic-size swimming pool with the spectators’ stand is modeled and distribution of velocity, temperature, relative humidity, and chlorine concentration have been determined. Also, the results have been analyzed in both cases: using air curtain and without air curtain. The results show that the air curtain can significantly reduce the influence of chlorine pollutants on the spectators' section, so the concentration of chlorine at spectators’ stand with the air curtain is about 0.00016 mg/m3 less than the case without air curtain. In this study, 65 multi node local thermal comfort model has been used to determine the thermal comfort of individuals. In the case of using the air curtain, the standard deviation of thermal comfort index for first to third rows are 0.26, 0.25, and 0.28 respectively; and in the absence of air curtain, for first to third rows the standard deviation of thermal comfort index are 0.33, 0.39 and 0.35, respectively. These results indicate that using the air curtain can lead the thermal sensation to be more favorable and more uniform.

https://mej.aut.ac.ir/article_3193_68a9750337a418a86fe06c1991a1d64c.pdf

Amirkabir University of Technology Amirkabir Journal of Mechanical Engineering 2008-6032 53 1 2021 03 21 An Experimental Investigation on the Convective Heat Transfer Coefficient and Nusselt Number in Water/Carbon Nanofluid An Experimental Investigation on the Convective Heat Transfer Coefficient and Nusselt Number in Water/Carbon Nanofluid 209 220 3642 10.22060/mej.2019.16148.6289 FA Amir Hossein Shiravi Department of Mechanical Engineering, Faculty of Mechanical engineering, Jundi-Shapur University of technology, Dezful, Iran Mojtaba Shafiee Department of Chemical Engineering, Faculty of Chemical Engineering, Jundi-Shapur University of Technology, Dezful, Iran Hadis Bostani Department of Mechanical Engineering, Jundi-Shapur University of Technology, Dezful, Iran Mohammad Firoozzadeh Department of Mechanical Engineering, Faculty of Mechanical Engineering, Jundi-Shapur University of technology, Dezful, Iran Maryam Bozorgmehrian Department of Mechanical Engineering, Mechanical faculty, Jundi-Shapur University of Technology, Dezful, Iran Journal Article 2019 04 17 The heat transfer coefficient of fluid is one of the most important effective factors on the performance of fluid in the heat transfer process. Due to the higher conductive heat transfer coefficient of metals than liquids, metal particles can be used to increase the heat transfer rate of liquids. Nanofluid is one of the novels and developing methods to improve the heat transfer rate in heat exchangers. In this paper, the main effective parameters (flow rate and concentration) on increasing the convective heat transfer coefficient of water carbon nanofluid compared with water as a base fluid, are investigated in the Reynolds range of 7,100 to 16,700. The results illustrate that increasing the Re leads to increase in the Nusselt number and convective heat transfer coefficient, and also to decrease the friction factor. It is also shown that at a constant Re, carbon nanofluid is able to enhance the convective heat transfer coefficient up to 10.17%, compared with pure water. It is found that adding carbon nanoparticles to water, initially leads to increasing the convective heat transfer coefficient, while this trend continues until the concentration of about 0.2 wt%, and then has a descending trend. In addition, the pressure drop was investigated due to changes in Re and was shown that the behavior of this curve is in agreement with Moody’s diagram. The heat transfer coefficient of fluid is one of the most important effective factors on the performance of fluid in the heat transfer process. Due to the higher conductive heat transfer coefficient of metals than liquids, metal particles can be used to increase the heat transfer rate of liquids. Nanofluid is one of the novels and developing methods to improve the heat transfer rate in heat exchangers. In this paper, the main effective parameters (flow rate and concentration) on increasing the convective heat transfer coefficient of water carbon nanofluid compared with water as a base fluid, are investigated in the Reynolds range of 7,100 to 16,700. The results illustrate that increasing the Re leads to increase in the Nusselt number and convective heat transfer coefficient, and also to decrease the friction factor. It is also shown that at a constant Re, carbon nanofluid is able to enhance the convective heat transfer coefficient up to 10.17%, compared with pure water. It is found that adding carbon nanoparticles to water, initially leads to increasing the convective heat transfer coefficient, while this trend continues until the concentration of about 0.2 wt%, and then has a descending trend. In addition, the pressure drop was investigated due to changes in Re and was shown that the behavior of this curve is in agreement with Moody’s diagram.

https://mej.aut.ac.ir/article_3642_300d1539c3b6aa1793b5678b857732cf.pdf

Amirkabir University of Technology Amirkabir Journal of Mechanical Engineering 2008-6032 53 1 2021 03 21 Numerical Simulation of Heat Transfer Turbulent Flow for Non-Newtonian Nanofluid in a Double Pipe Helical Heat Exchanger Numerical Simulation of Heat Transfer Turbulent Flow for Non-Newtonian Nanofluid in a Double Pipe Helical Heat Exchanger 221 240 3488 10.22060/mej.2019.16033.6256 FA Kourosh Javaherdeh Instructor of Department of Mechanical Engineering, Faculty of Engineering, University of Guilan 0000-0002-1570-011X Seyed Shahab Mozafarie Faculty of Mechanical Engineering, University of Guilan, Rash, Iran Zeinab Zare Talab Faculty of Mechanical Engineering, University of Guilan, Rasht, Iran Journal Article 2019 03 18 In this research, the thermal and hydrodynamic behavior of a non-Newtonian nanofluid turbulent flow in the counterflow arrangement in a double pipe helical heat exchanger is numerically simulated. A solution of carboxymethyl cellulose powder in water with a mass percentage of 0.1% with a nanoparticle of aluminum oxide as a working fluid has been used. The computational fluid dynamics commercial software Fluent was used to solve the governing equations, the results were in a good agreement with experimental data. The effect of important parameters such as curvature, Reynolds number and volume percentage of aluminum oxide nanoparticles on the heat transfer has been investigated. The results show that as the curvature ratio increases in constant Dean (Dn) numbers, the Nu number and the coefficient of friction increase. The addition of nanoparticles of aluminum oxide to the base fluid for the flow with the constant Reynolds and Dn number increases the heat transfer and increases the pressure drop in the helically coiled tubes. The centrifugal force generated by the curvature of the coiled tubes results in a secondary flow in the heat exchanger so that the heat transfer and pressure drop increased up to 35% and 30%, respectively, compared to the straight tubes. The effect of heat transfer enhancement methods on the hydrodynamic index has also been studied, so that in the helical coils, the amount of hydrodynamic index increased with decreasing curvature ratio and increasing the volume concentration of nanoparticles. In this research, the thermal and hydrodynamic behavior of a non-Newtonian nanofluid turbulent flow in the counterflow arrangement in a double pipe helical heat exchanger is numerically simulated. A solution of carboxymethyl cellulose powder in water with a mass percentage of 0.1% with a nanoparticle of aluminum oxide as a working fluid has been used. The computational fluid dynamics commercial software Fluent was used to solve the governing equations, the results were in a good agreement with experimental data. The effect of important parameters such as curvature, Reynolds number and volume percentage of aluminum oxide nanoparticles on the heat transfer has been investigated. The results show that as the curvature ratio increases in constant Dean (Dn) numbers, the Nu number and the coefficient of friction increase. The addition of nanoparticles of aluminum oxide to the base fluid for the flow with the constant Reynolds and Dn number increases the heat transfer and increases the pressure drop in the helically coiled tubes. The centrifugal force generated by the curvature of the coiled tubes results in a secondary flow in the heat exchanger so that the heat transfer and pressure drop increased up to 35% and 30%, respectively, compared to the straight tubes. The effect of heat transfer enhancement methods on the hydrodynamic index has also been studied, so that in the helical coils, the amount of hydrodynamic index increased with decreasing curvature ratio and increasing the volume concentration of nanoparticles.

https://mej.aut.ac.ir/article_3488_c7b90b0fc23725f299b47c5224e6ec0d.pdf

Amirkabir University of Technology Amirkabir Journal of Mechanical Engineering 2008-6032 53 1 2021 03 21 Investigation of Heat Transfer of Non-Newtonian Pseudo-Plastic Fluids in Porous Heat Exchangers Investigation of Heat Transfer of Non-Newtonian Pseudo-Plastic Fluids in Porous Heat Exchangers 241 258 3448 10.22060/mej.2019.15536.6153 FA Amin Reza Noghreabadi Mechanical Engineering Department, Faculty of Engineering, Shahid Chamran of Ahvaz University, Ahvaz, IRAN Kasra Ayoubi Ayoubloo Mechanical Engineering Department, Faculty of Engineering, Shahid Chamran of Ahvaz University, Ahvaz, Iran Reza Bahoosh Kazerooni Mechanical Engineering Department, Faculty of Engineering, Shahid Chamran of Ahvaz University, Ahvaz, Iran Mohammad Ghalambaz Assistant professor, Department of Mechanical Engineering, Dezful Branch, Islamic Azad University, Dezful, Iran 0000-0003-0965-2358 Journal Article 2018 12 29 In this paper, the natural heat transfer of Rayleigh-Benard's non-Newtonian Pseudo-Plastics fluid in a tube heat exchanger with its left wall lined with a porous layer of a thickness l is considered numerically for an unstable state of laminar. The lower wall of the heat exchanger is at constant temperature Thand the upper wall at Tc temperature (Th>Tc). The walls are left and right insulated. The dimensionless governing equations are solved by the finite element method and the accuracy of the results is compared with previous studies. The results show that, in a large Rayleigh number, the average Nusselt number increases due to the fact that the natural heat transfer is more than conduction heat transfer. Also, in small Darcy numbers, the flow permeability is very low which causes reduce natural heat transfer convection. The results show that by decreasing the Power-law index, the non-dimensional temperature is reduced and the lowest non-dimensional temperature is obtained for the lowest Power-law index. On the other hand, with the increase of the Power-law index in a constant Rayleigh number and the passage of time, the increase of natural heat transfer occurs in the tube. Also, the Rayleigh number decreases with the increase of the Power-law index to start the natural convection in the heat exchanger. In this paper, the natural heat transfer of Rayleigh-Benard's non-Newtonian Pseudo-Plastics fluid in a tube heat exchanger with its left wall lined with a porous layer of a thickness l is considered numerically for an unstable state of laminar. The lower wall of the heat exchanger is at constant temperature Thand the upper wall at Tc temperature (Th>Tc). The walls are left and right insulated. The dimensionless governing equations are solved by the finite element method and the accuracy of the results is compared with previous studies. The results show that, in a large Rayleigh number, the average Nusselt number increases due to the fact that the natural heat transfer is more than conduction heat transfer. Also, in small Darcy numbers, the flow permeability is very low which causes reduce natural heat transfer convection. The results show that by decreasing the Power-law index, the non-dimensional temperature is reduced and the lowest non-dimensional temperature is obtained for the lowest Power-law index. On the other hand, with the increase of the Power-law index in a constant Rayleigh number and the passage of time, the increase of natural heat transfer occurs in the tube. Also, the Rayleigh number decreases with the increase of the Power-law index to start the natural convection in the heat exchanger.

https://mej.aut.ac.ir/article_3448_c5bbd980e5ab2c17413ec02bd757a9e5.pdf

Amirkabir University of Technology Amirkabir Journal of Mechanical Engineering 2008-6032 53 1 2021 03 21 Effects of Magnetic Field on Natural Convection of Non-Newtonian Fluid in a Square Enclosure with a Central Heat Source Effects of Magnetic Field on Natural Convection of Non-Newtonian Fluid in a Square Enclosure with a Central Heat Source 259 278 3513 10.22060/mej.2019.16101.6274 FA Akram Jahanbakhshi Shahrekord University, Shahrekord Afshin Ahmadi Nadooshan Mechanical Engineering Department, Shahrekord University, Shahrekord 0000-0003-4345-9527 Journal Article 2019 04 09 In this study, the incompressible laminar flow of non-Newtonian fluid is studied in a cavity with a central heat source under a uniform inclined magnetic field. The governing equations are converted into nonlinear ordinary differential equations using similarity transformations and solved using finite difference based numerical methods. In the current study, the effect of non-Newtonian power-law fluid is investigated for power-law indices of 0.75, 1 and 1.4. The results are compared with the ones in which the magnetic field is not applied. It is found that the implementation of a magnetic field for different fluid indices in different Rayleigh numbers does not show similar behaviors and the results show that the magnetic field affects the convection flow, leading to a reduction in it. Also can be said that with the implementation of a magnetic field in the range of indices n ≥ 1 for power-law model fluid, increased Rayleigh number leads to reduced average Nusselt number and for n ˂ 1, the average Nusselt increases. For n ˂ 1, with increased Rayleigh number in the presence of a fixed magnetic field, free convection can be weakened while this trend for n ˂ 1 occurs with reduced Rayleigh number. In this study, the incompressible laminar flow of non-Newtonian fluid is studied in a cavity with a central heat source under a uniform inclined magnetic field. The governing equations are converted into nonlinear ordinary differential equations using similarity transformations and solved using finite difference based numerical methods. In the current study, the effect of non-Newtonian power-law fluid is investigated for power-law indices of 0.75, 1 and 1.4. The results are compared with the ones in which the magnetic field is not applied. It is found that the implementation of a magnetic field for different fluid indices in different Rayleigh numbers does not show similar behaviors and the results show that the magnetic field affects the convection flow, leading to a reduction in it. Also can be said that with the implementation of a magnetic field in the range of indices n ≥ 1 for power-law model fluid, increased Rayleigh number leads to reduced average Nusselt number and for n ˂ 1, the average Nusselt increases. For n ˂ 1, with increased Rayleigh number in the presence of a fixed magnetic field, free convection can be weakened while this trend for n ˂ 1 occurs with reduced Rayleigh number.

https://mej.aut.ac.ir/article_3513_0ffaca95e3e5242ba1097ad8a9a6e95d.pdf

Amirkabir University of Technology Amirkabir Journal of Mechanical Engineering 2008-6032 53 1 2021 03 21 Experimental Investigation on the Thermal Resistance of Straight Heat Pipes with Double-Ended Cooling and Middle-Heating at Different Tilt Angles Experimental Investigation on the Thermal Resistance of Straight Heat Pipes with Double-Ended Cooling and Middle-Heating at Different Tilt Angles 279 302 3490 10.22060/mej.2019.15733.6194 FA Behnam Habibnezhad Ledari Department of Mechanical Engineering, University of Kashan, Kashan, Iran Majid Sabzpooshani Department of Mechanical Engineering, University of Kashan, Kashan, Iran Journal Article 2019 02 01 An experimental study has been investigated on the thermal resistance of straight heat pipes with double-ended cooling and middle heating at different tilt angles. Two cooling blocks installed on both ends of heat pipes and a coil heater placed in the middle as the condenser and evaporator sections respectively. The experiments were conducted at inclinations 0° to 90° for heat inputs 20 to 80 W. The effects of heat input variation, cooling water flow rate and tilt angle on the thermal resistance of heat pipes were studied. The obtained results compared with the conventional heat pipes. The results showed that by using the new cooling approach, the thermal resistance of the heat pipes can be reduced significantly. Also, in low heat inputs, increasing the cooling water flow rate increases the thermal performance of the heat pipes. The experimental results indicated that the tilt angle has a significant effect on the thermal resistance of the heat pipes. The minimum thermal resistance and the maximum effective thermal conductivity coefficient values are 0.2533 °C/W and 14072.65 W/m°C respectively, and they were observed at the tilt angle equal to 60° and for heat input of 60 W. An experimental study has been investigated on the thermal resistance of straight heat pipes with double-ended cooling and middle heating at different tilt angles. Two cooling blocks installed on both ends of heat pipes and a coil heater placed in the middle as the condenser and evaporator sections respectively. The experiments were conducted at inclinations 0° to 90° for heat inputs 20 to 80 W. The effects of heat input variation, cooling water flow rate and tilt angle on the thermal resistance of heat pipes were studied. The obtained results compared with the conventional heat pipes. The results showed that by using the new cooling approach, the thermal resistance of the heat pipes can be reduced significantly. Also, in low heat inputs, increasing the cooling water flow rate increases the thermal performance of the heat pipes. The experimental results indicated that the tilt angle has a significant effect on the thermal resistance of the heat pipes. The minimum thermal resistance and the maximum effective thermal conductivity coefficient values are 0.2533 °C/W and 14072.65 W/m°C respectively, and they were observed at the tilt angle equal to 60° and for heat input of 60 W.

https://mej.aut.ac.ir/article_3490_72f67e70f6b7cdc4cc893edaddf0c4c6.pdf

Amirkabir University of Technology Amirkabir Journal of Mechanical Engineering 2008-6032 53 1 2021 03 21 Real Time Solution for Inverse Heat Conduction Problem in One-Dimensional Plate Utilizing Fuzzy- Proportional–Integral–Derivative Controller Real Time Solution for Inverse Heat Conduction Problem in One-Dimensional Plate Utilizing Fuzzy- Proportional–Integral–Derivative Controller 303 316 3574 10.22060/mej.2019.16092.6269 FA Amir Hossein Rabiee mechanical engineering, arak university of technology Somayeh Farahani صنعتی اراک-مهندسی مکانیک Journal Article 2019 04 09 This paper dealing with a novel algorithm based on features of fuzzy- proportional–integral–derivative controllers to estimate heat flux on the inverse heat conduction problems. The main structure of Fuzzy- proportional–integral–derivative is a proportional–integral–derivative controller in which the proportional, integrator and the derivative gains are obtained online by fuzzy system. The input of the algorithm is the measured temperatures within the model. In each time-step, the smart controller calculates the proper heat flux in order to adjust the measured temperature with the desired input temperature. The model studied a flat plate with an insulated surface and an active level that affects the variable heat flux at the time. The variation of heat flux with time can be considered to be constant, step, and triangular. The measured temperatures are obtained at the active and inactive surface with numerical simulation. The effect of noise level at the measurement temperatures on the accuracy of the proposed method is investigated. The estimations and error analysis indicate that this algorithm is very successful in estimating the different forms of heat flux with different amounts of noise and the different thermocouple positions in the wall. The accuracy of the proposed sequence method is higher than that of the Tikhonov method. This paper dealing with a novel algorithm based on features of fuzzy- proportional–integral–derivative controllers to estimate heat flux on the inverse heat conduction problems. The main structure of Fuzzy- proportional–integral–derivative is a proportional–integral–derivative controller in which the proportional, integrator and the derivative gains are obtained online by fuzzy system. The input of the algorithm is the measured temperatures within the model. In each time-step, the smart controller calculates the proper heat flux in order to adjust the measured temperature with the desired input temperature. The model studied a flat plate with an insulated surface and an active level that affects the variable heat flux at the time. The variation of heat flux with time can be considered to be constant, step, and triangular. The measured temperatures are obtained at the active and inactive surface with numerical simulation. The effect of noise level at the measurement temperatures on the accuracy of the proposed method is investigated. The estimations and error analysis indicate that this algorithm is very successful in estimating the different forms of heat flux with different amounts of noise and the different thermocouple positions in the wall. The accuracy of the proposed sequence method is higher than that of the Tikhonov method.

https://mej.aut.ac.ir/article_3574_1b9f38268c50805669fd8caf8f3cc84a.pdf