The Experts below are selected from a list of 189 Experts worldwide ranked by ideXlab platform
Amin Shahsavar - One of the best experts on this subject based on the ideXlab platform.
-
Numerical study of the possibility of improving the hydrothermal performance of an elliptical double-pipe heat exchanger through the simultaneous use of twisted tubes and non-Newtonian nanofluid
Journal of Thermal Analysis and Calorimetry, 2021Co-Authors: Amin Shahsavar, Masoud Afrand, Mohammad Amin Bakhshizadeh, Müslüm Arıcı, Sara RostamiAbstract:In this investigation, the combined use of twisted tubes and nanofluid (NF) to augment the performance of a double-pipe heat exchanger (DPHE) has been conSidered numerically. Steady-state laminar flow of the cold non-Newtonian CuO NF and hot water pass inSide the tube Side and Annulus Side, respectively. The base fluid is the aqueous solution of 0.5 mass% carboxymethyl cellulose. The effects of the Reynolds number ( $${\text{Re}}$$ Re ), the volume concentration of nanoparticles ( $$\varphi$$ φ ) and twist pitch on the performance metrics are examined, and the outcomes are compared with those a plain DPHE. The outcomes showed that the increase in Re has desirable effects such as improved heat transfer and heat exchanger effectiveness, and unpleasant effects such as increased pressure drop and pumping power. Moreover, it was found that except for $$\varphi \le 1.5\%$$ φ ≤ 1.5 % and $${\text{Re}} =$$ Re = 500, the NF performs better than the base fluid. In addition, it was reported that the variation pattern of overall hydrothermal performance of NF with twist pitch is ascending–descending. Furthermore, the outcomes illustrated that the overall hydrothermal performance of twisted DPHE is superior to that of the plain DPHE, and its highest value is 2.671, which belongs to case of $${\text{Re}} =$$ Re = 2000, $$\varphi =$$ φ = 3% and twist pitch = 4 mm.
-
Numerical study of the possibility of improving the hydrothermal performance of an elliptical double-pipe heat exchanger through the simultaneous use of twisted tubes and non-Newtonian nanofluid
Journal of Thermal Analysis and Calorimetry, 2020Co-Authors: Amin Shahsavar, Masoud Afrand, Mohammad Amin Bakhshizadeh, Müslüm Arıcı, Sara RostamiAbstract:In this investigation, the combined use of twisted tubes and nanofluid (NF) to augment the performance of a double-pipe heat exchanger (DPHE) has been conSidered numerically. Steady-state laminar flow of the cold non-Newtonian CuO NF and hot water pass inSide the tube Side and Annulus Side, respectively. The base fluid is the aqueous solution of 0.5 mass% carboxymethyl cellulose. The effects of the Reynolds number ( $${\text{Re}}$$ ), the volume concentration of nanoparticles ( $$\varphi$$ ) and twist pitch on the performance metrics are examined, and the outcomes are compared with those a plain DPHE. The outcomes showed that the increase in Re has desirable effects such as improved heat transfer and heat exchanger effectiveness, and unpleasant effects such as increased pressure drop and pumping power. Moreover, it was found that except for $$\varphi \le 1.5\%$$ and $${\text{Re}} =$$ 500, the NF performs better than the base fluid. In addition, it was reported that the variation pattern of overall hydrothermal performance of NF with twist pitch is ascending–descending. Furthermore, the outcomes illustrated that the overall hydrothermal performance of twisted DPHE is superior to that of the plain DPHE, and its highest value is 2.671, which belongs to case of $${\text{Re}} =$$ 2000, $$\varphi =$$ 3% and twist pitch = 4 mm.
-
Impact of variable fluid properties on forced convection of Fe_3O_4/CNT/water hybrid nanofluid in a double-pipe mini-channel heat exchanger
Journal of Thermal Analysis and Calorimetry, 2019Co-Authors: Amin Shahsavar, Ali Godini, Pouyan Talebizadeh Sardari, Davood Toghraie, Hamzeh SalehipourAbstract:The objective of this study is to assess the hydrothermal performance of a non-Newtonian hybrid nanofluid with temperature-dependent thermal conductivity and viscosity compared with a Newtonian hybrid nanofluid with constant thermophysical properties. A counter-current double-pipe mini-channel heat exchanger is studied to analyze the effects of the hybrid nanofluid. The nanofluid is employed as the coolant in the tube Side, while the hot water flows in the Annulus Side. Two different nanoparticles including tetramethylammonium hydroxide-coated Fe_3O_4 (magnetite) nanoparticles and gum arabic-coated carbon nanotubes are used to prepare the water-based hybrid nanofluid. The results demonstrated that the non-Newtonian hybrid nanofluid always has a higher heat transfer rate, overall heat transfer coefficient, and effectiveness than those of the Newtonian hybrid nanofluid, while the opposite is true for the pressure drop, pumping power, and performance evaluation criterion. Supposing that the Fe_3O_4-carbon nanotube/water hybrid nanofluid is a Newtonian fluid with constant thermal conductivity and viscosity, there leads to large error in the computation of pressure drop (1.5–9.71%), pumping power (1.5–9.71%), and performance evaluation criterion (18.24–19.60%), whereas the errors in the computation of heat transfer rate, overall heat transfer coefficient, and effectiveness are not conSiderable (less than 2.91%).
-
Impact of variable fluid properties on forced convection of Fe 3 O 4 /CNT/water hybrid nanofluid in a double-pipe mini-channel heat exchanger
Journal of Thermal Analysis and Calorimetry, 2019Co-Authors: Amin Shahsavar, Ali Godini, Pouyan Talebizadeh Sardari, Davood Toghraie, Hamzeh SalehipourAbstract:The objective of this study is to assess the hydrothermal performance of a non-Newtonian hybrid nanofluid with temperature-dependent thermal conductivity and viscosity compared with a Newtonian hybrid nanofluid with constant thermophysical properties. A counter-current double-pipe mini-channel heat exchanger is studied to analyze the effects of the hybrid nanofluid. The nanofluid is employed as the coolant in the tube Side, while the hot water flows in the Annulus Side. Two different nanoparticles including tetramethylammonium hydroxide-coated Fe3O4 (magnetite) nanoparticles and gum arabic-coated carbon nanotubes are used to prepare the water-based hybrid nanofluid. The results demonstrated that the non-Newtonian hybrid nanofluid always has a higher heat transfer rate, overall heat transfer coefficient, and effectiveness than those of the Newtonian hybrid nanofluid, while the opposite is true for the pressure drop, pumping power, and performance evaluation criterion. Supposing that the Fe3O4-carbon nanotube/water hybrid nanofluid is a Newtonian fluid with constant thermal conductivity and viscosity, there leads to large error in the computation of pressure drop (1.5–9.71%), pumping power (1.5–9.71%), and performance evaluation criterion (18.24–19.60%), whereas the errors in the computation of heat transfer rate, overall heat transfer coefficient, and effectiveness are not conSiderable (less than 2.91%).
-
Laminar forced convection performance of non-Newtonian water-CNT/Fe3O4 nano-fluid inSide a minichannel hairpin heat exchanger: Effect of inlet temperature
Powder Technology, 2019Co-Authors: W.i. Liu, Abdullah A.a.a. Al-rashed, Amin Shahsavar, Ali Sulaiman Alsagri, Boshra Mahmoudi, Masoud AfrandAbstract:Abstract This numerical study aims to focus on the effect of difference between the inlet temperatures of working fluids on the hydrothermal characteristics of a counter-current minichannel hairpin heat exchanger. The water flows in the Annulus Side and the water based hybrid nano-fluid containing Fe3O4 and carbon nanotubes (CNTs) passes through the tube Side of heat exchanger. Temperature-dependent thermal conductivity and viscosity are conSidered for the non-Newtonian hybrid nano-fluid. The effects of Fe3O4 and CNT volume fractions as well as the Reynolds number on the performance metrics of the heat exchanger are also assessed. The results revealed that the increase of difference between the inlet temperatures of working fluids leads to the augmentation of heat transfer rate, overall heat transfer coefficient (except at Reynolds number of 500), heat exchanger effectiveness and PEC; while the pumping power diminishes with the increase of inlet water temperature.
Mehdi Bahiraei - One of the best experts on this subject based on the ideXlab platform.
-
Analyzing performance of a ribbed triple-tube heat exchanger operated with graphene nanoplatelets nanofluid based on entropy generation and exergy destruction
International Communications in Heat and Mass Transfer, 2019Co-Authors: Nima Mazaheri, Mehdi Bahiraei, Hooman Abdi Chaghakaboodi, Hossein MoayediAbstract:Abstract The current investigation aims to study the second law features of an innovative nanofluid having hybrid nanoparticles of graphene nanoplatelets–Pt through a ribbed triple-tube heat exchanger (RTTHX). The hot nanofluid passes inSide the ribbed Annulus Side, the cold water enters inSide the inner tube Side, and the normal water moves through the outer Annulus Side. The effects of nanoparticle weight fraction as well as geometrical parameters including the pitch and height of the ribs are evaluated. The total entropy generation rate of heat exchanger reduces by the weight fraction increase, which demonstrates the great advantage of employing the nanofluid. Both increasing the rib height and rib pitch decrement reduce total entropy production of the nanofluid, whereas increase the total entropy production of RTTHX. Moreover, the total exergy destruction of whole heat exchanger decreases by increase of the weight fraction, such that it reduces about 23% with increasing the weight fraction from 0 to 0.1% at rib pitch of 150 mm and rib height of 3 mm. Furthermore, the second law efficiency enhances with the weight fraction increment, while reduces with the rib pitch decrement and increasing rib height. The second law efficiency has great values in all conditions under study.
-
Application of a hybrid nanofluid containing graphene nanoplatelet–platinum composite powder in a triple-tube heat exchanger equipped with inserted ribs
Applied Thermal Engineering, 2019Co-Authors: Mehdi Bahiraei, Nima Mazaheri, Ali RizehvandiAbstract:Abstract The current paper attempts to numerically examine the hydrothermal characteristics and energy performance of a hybrid nanofluid containing graphene nanoplatelet–platinum composite powder in a triple-tube heat exchanger equipped with inserted ribs. The nanofluid flows in the inner Annulus Side, whereas the cold water and normal water flow in the tube Side and outer Annulus Side, respectively. The ribs are installed on the outer surface of the inner tube. The overall heat transfer coefficient, effectiveness and heat transfer rate of the heat exchanger are enhanced by increasing the nanoparticle concentration and rib height and by decreasing the rib pitch. The pressure drop is more intense in the cases of smaller rib pitch and higher rib height because the particles pass longer routes under these conditions. Based on the heat transfer enhancement, the case with greater rib height and smaller rib pitch at the highest concentration is suggested, because demonstrates the greatest thermal performance for the heat exchanger. Whereas, in the view of the energy efficiency, the heat exchanger with the smaller rib height and lower rib pitch with the highest nanoparticle concentration is recommended since the performance index of this case is greater than that of the other cases.
-
Thermal and hydraulic characteristics of a minichannel heat exchanger operated with a non-Newtonian hybrid nanofluid
Journal of the Taiwan Institute of Chemical Engineers, 2018Co-Authors: Mehdi Bahiraei, Ali Godini, Amin ShahsavarAbstract:Abstract In this study, thermal and hydraulic characteristics of a non-Newtonian hybrid nanofluid are investigated in a double-tube minichannel heat exchanger. The nanofluid contains two different nanoparticles, namely Tetra Methyl Ammonium Hydroxide (TMAH) coated Fe3O4 nanoparticles and Gum Arabic (GA) coated Carbon Nanotubes (CNTs). The nanofluid and water flow in the tube Side and Annulus Side of the heat exchanger, respectively. Variable thermal conductivity and viscosity are applied in the simulations. Numerical solutions are performed based on both Reynolds number and mass flow rate, and the heat transfer rate in the heat exchanger, overall heat transfer coefficient, effectiveness, pressure drop, pumping power, and performance index are evaluated under different conditions. The results show that adding the nanoparticles causes a further increment in heat transfer rate at lower Reynolds numbers, such that the increase in heat transfer rate of the nanofluid compared with water at Reynolds numbers 500 and 2000 is 53.8% and 28.6%, respectively. The findings obtained show a promising view for use of this hybrid ferrofluid in mini heat exchangers.
-
Efficacy of an eco-friendly nanofluid in a miniature heat exchanger regarding to arrangement of silver nanoparticles
Energy Conversion and Management, 2017Co-Authors: Mehdi Bahiraei, Seyed Mohsen Naghibzadeh, Mohammad JamshidmofidAbstract:Abstract The performance and hydrothermal characteristics of a biologically produced nanofluid in a miniature counter-flow double-tube heat exchanger are investigated conSidering particle migration. Hot water flows in the Annulus Side, and the nanofluid is employed as the coolant in the tube Side. The particles used are silver nanoparticles synthesized through plant extract method from green tea leaves. Particle migration disturbs particle concentration distribution, and a more non-uniform concentration is developed by increasing either Reynolds number or mean concentration. The results reveal that at great concentrations and Reynolds numbers, particle migration possesses a significant effect on efficacy of the heat exchanger. Particle migration increases the heat transfer rate while decreasing pumping power. As concentration and Reynolds number increase, the overall heat transfer coefficient and heat transfer rate enhance. The effectiveness and number of transfer units decrease by increasing Reynolds number, and augment with concentration increment. Pumping power significantly intensifies by increasing Reynolds number, but it reduces by augmenting concentration, which is a very positive finding. In addition, the ratio of heat transfer rate to pressure drop increases with concentration increment and therefore, the nanofluid has greater merit to be applied in the heat exchanger at higher concentrations. Moreover, the overall heat transfer coefficient enhances by increasing the water temperature in Annulus Side inlet, which is due to an increase in convective heat transfer coefficient of the tube Side because of the nanofluid thermal conductivity augmentation.
-
Irreversibility analysis for flow of a non-Newtonian hybrid nanofluid containing coated CNT/Fe3O4 nanoparticles in a minichannel heat exchanger
Applied Thermal Engineering, 2017Co-Authors: Mehdi Bahiraei, Mohamad Berahmand, Amin ShahsavarAbstract:Abstract Irreversibilities caused by heat transfer and friction are evaluated for a non-Newtonian hybrid nanofluid flow in a double-tube minichannel heat exchanger by calculating entropy generation rates. The nanofluids are prepared by dispersing two different nanoparticles, namely Tetra Methyl Ammonium Hydroxide (TMAH) coated Fe 3 O 4 nanoparticles and Gum Arabic (GA) coated Carbon Nanotubes (CNTs). Variable thermophysical properties are employed such that thermal conductivity is conSidered dependent on temperature and concentration, while viscosity is dependent on temperature, concentration and shear rate. The results show that heat transfer is the main cause in entropy generation at low concentrations while friction is the main factor at high concentrations. By increasing water temperature at the Annulus Side, the nanofluid thermal entropy generation increases while the nanofluid frictional entropy generation decreases. For low magnetite concentration, maximum thermal entropy generation occurs at the lowest CNT concentration while for high magnetite concentration, it happens at the highest CNT concentration. By increasing the Reynolds number, minimum point of thermal entropy generation moves toward smaller magnetite concentrations. In addition, at low magnetite concentration, total entropy generation rate possesses a minimum (optimal) point with respect to CNT concentration while an ascending trend is observed at high magnetite concentrations.
Hamzeh Salehipour - One of the best experts on this subject based on the ideXlab platform.
-
Impact of variable fluid properties on forced convection of Fe_3O_4/CNT/water hybrid nanofluid in a double-pipe mini-channel heat exchanger
Journal of Thermal Analysis and Calorimetry, 2019Co-Authors: Amin Shahsavar, Ali Godini, Pouyan Talebizadeh Sardari, Davood Toghraie, Hamzeh SalehipourAbstract:The objective of this study is to assess the hydrothermal performance of a non-Newtonian hybrid nanofluid with temperature-dependent thermal conductivity and viscosity compared with a Newtonian hybrid nanofluid with constant thermophysical properties. A counter-current double-pipe mini-channel heat exchanger is studied to analyze the effects of the hybrid nanofluid. The nanofluid is employed as the coolant in the tube Side, while the hot water flows in the Annulus Side. Two different nanoparticles including tetramethylammonium hydroxide-coated Fe_3O_4 (magnetite) nanoparticles and gum arabic-coated carbon nanotubes are used to prepare the water-based hybrid nanofluid. The results demonstrated that the non-Newtonian hybrid nanofluid always has a higher heat transfer rate, overall heat transfer coefficient, and effectiveness than those of the Newtonian hybrid nanofluid, while the opposite is true for the pressure drop, pumping power, and performance evaluation criterion. Supposing that the Fe_3O_4-carbon nanotube/water hybrid nanofluid is a Newtonian fluid with constant thermal conductivity and viscosity, there leads to large error in the computation of pressure drop (1.5–9.71%), pumping power (1.5–9.71%), and performance evaluation criterion (18.24–19.60%), whereas the errors in the computation of heat transfer rate, overall heat transfer coefficient, and effectiveness are not conSiderable (less than 2.91%).
-
Impact of variable fluid properties on forced convection of Fe 3 O 4 /CNT/water hybrid nanofluid in a double-pipe mini-channel heat exchanger
Journal of Thermal Analysis and Calorimetry, 2019Co-Authors: Amin Shahsavar, Ali Godini, Pouyan Talebizadeh Sardari, Davood Toghraie, Hamzeh SalehipourAbstract:The objective of this study is to assess the hydrothermal performance of a non-Newtonian hybrid nanofluid with temperature-dependent thermal conductivity and viscosity compared with a Newtonian hybrid nanofluid with constant thermophysical properties. A counter-current double-pipe mini-channel heat exchanger is studied to analyze the effects of the hybrid nanofluid. The nanofluid is employed as the coolant in the tube Side, while the hot water flows in the Annulus Side. Two different nanoparticles including tetramethylammonium hydroxide-coated Fe3O4 (magnetite) nanoparticles and gum arabic-coated carbon nanotubes are used to prepare the water-based hybrid nanofluid. The results demonstrated that the non-Newtonian hybrid nanofluid always has a higher heat transfer rate, overall heat transfer coefficient, and effectiveness than those of the Newtonian hybrid nanofluid, while the opposite is true for the pressure drop, pumping power, and performance evaluation criterion. Supposing that the Fe3O4-carbon nanotube/water hybrid nanofluid is a Newtonian fluid with constant thermal conductivity and viscosity, there leads to large error in the computation of pressure drop (1.5–9.71%), pumping power (1.5–9.71%), and performance evaluation criterion (18.24–19.60%), whereas the errors in the computation of heat transfer rate, overall heat transfer coefficient, and effectiveness are not conSiderable (less than 2.91%).
Ali Godini - One of the best experts on this subject based on the ideXlab platform.
-
Impact of variable fluid properties on forced convection of Fe_3O_4/CNT/water hybrid nanofluid in a double-pipe mini-channel heat exchanger
Journal of Thermal Analysis and Calorimetry, 2019Co-Authors: Amin Shahsavar, Ali Godini, Pouyan Talebizadeh Sardari, Davood Toghraie, Hamzeh SalehipourAbstract:The objective of this study is to assess the hydrothermal performance of a non-Newtonian hybrid nanofluid with temperature-dependent thermal conductivity and viscosity compared with a Newtonian hybrid nanofluid with constant thermophysical properties. A counter-current double-pipe mini-channel heat exchanger is studied to analyze the effects of the hybrid nanofluid. The nanofluid is employed as the coolant in the tube Side, while the hot water flows in the Annulus Side. Two different nanoparticles including tetramethylammonium hydroxide-coated Fe_3O_4 (magnetite) nanoparticles and gum arabic-coated carbon nanotubes are used to prepare the water-based hybrid nanofluid. The results demonstrated that the non-Newtonian hybrid nanofluid always has a higher heat transfer rate, overall heat transfer coefficient, and effectiveness than those of the Newtonian hybrid nanofluid, while the opposite is true for the pressure drop, pumping power, and performance evaluation criterion. Supposing that the Fe_3O_4-carbon nanotube/water hybrid nanofluid is a Newtonian fluid with constant thermal conductivity and viscosity, there leads to large error in the computation of pressure drop (1.5–9.71%), pumping power (1.5–9.71%), and performance evaluation criterion (18.24–19.60%), whereas the errors in the computation of heat transfer rate, overall heat transfer coefficient, and effectiveness are not conSiderable (less than 2.91%).
-
Impact of variable fluid properties on forced convection of Fe 3 O 4 /CNT/water hybrid nanofluid in a double-pipe mini-channel heat exchanger
Journal of Thermal Analysis and Calorimetry, 2019Co-Authors: Amin Shahsavar, Ali Godini, Pouyan Talebizadeh Sardari, Davood Toghraie, Hamzeh SalehipourAbstract:The objective of this study is to assess the hydrothermal performance of a non-Newtonian hybrid nanofluid with temperature-dependent thermal conductivity and viscosity compared with a Newtonian hybrid nanofluid with constant thermophysical properties. A counter-current double-pipe mini-channel heat exchanger is studied to analyze the effects of the hybrid nanofluid. The nanofluid is employed as the coolant in the tube Side, while the hot water flows in the Annulus Side. Two different nanoparticles including tetramethylammonium hydroxide-coated Fe3O4 (magnetite) nanoparticles and gum arabic-coated carbon nanotubes are used to prepare the water-based hybrid nanofluid. The results demonstrated that the non-Newtonian hybrid nanofluid always has a higher heat transfer rate, overall heat transfer coefficient, and effectiveness than those of the Newtonian hybrid nanofluid, while the opposite is true for the pressure drop, pumping power, and performance evaluation criterion. Supposing that the Fe3O4-carbon nanotube/water hybrid nanofluid is a Newtonian fluid with constant thermal conductivity and viscosity, there leads to large error in the computation of pressure drop (1.5–9.71%), pumping power (1.5–9.71%), and performance evaluation criterion (18.24–19.60%), whereas the errors in the computation of heat transfer rate, overall heat transfer coefficient, and effectiveness are not conSiderable (less than 2.91%).
-
Thermal and hydraulic characteristics of a minichannel heat exchanger operated with a non-Newtonian hybrid nanofluid
Journal of the Taiwan Institute of Chemical Engineers, 2018Co-Authors: Mehdi Bahiraei, Ali Godini, Amin ShahsavarAbstract:Abstract In this study, thermal and hydraulic characteristics of a non-Newtonian hybrid nanofluid are investigated in a double-tube minichannel heat exchanger. The nanofluid contains two different nanoparticles, namely Tetra Methyl Ammonium Hydroxide (TMAH) coated Fe3O4 nanoparticles and Gum Arabic (GA) coated Carbon Nanotubes (CNTs). The nanofluid and water flow in the tube Side and Annulus Side of the heat exchanger, respectively. Variable thermal conductivity and viscosity are applied in the simulations. Numerical solutions are performed based on both Reynolds number and mass flow rate, and the heat transfer rate in the heat exchanger, overall heat transfer coefficient, effectiveness, pressure drop, pumping power, and performance index are evaluated under different conditions. The results show that adding the nanoparticles causes a further increment in heat transfer rate at lower Reynolds numbers, such that the increase in heat transfer rate of the nanofluid compared with water at Reynolds numbers 500 and 2000 is 53.8% and 28.6%, respectively. The findings obtained show a promising view for use of this hybrid ferrofluid in mini heat exchangers.
Masoud Afrand - One of the best experts on this subject based on the ideXlab platform.
-
Numerical study of the possibility of improving the hydrothermal performance of an elliptical double-pipe heat exchanger through the simultaneous use of twisted tubes and non-Newtonian nanofluid
Journal of Thermal Analysis and Calorimetry, 2021Co-Authors: Amin Shahsavar, Masoud Afrand, Mohammad Amin Bakhshizadeh, Müslüm Arıcı, Sara RostamiAbstract:In this investigation, the combined use of twisted tubes and nanofluid (NF) to augment the performance of a double-pipe heat exchanger (DPHE) has been conSidered numerically. Steady-state laminar flow of the cold non-Newtonian CuO NF and hot water pass inSide the tube Side and Annulus Side, respectively. The base fluid is the aqueous solution of 0.5 mass% carboxymethyl cellulose. The effects of the Reynolds number ( $${\text{Re}}$$ Re ), the volume concentration of nanoparticles ( $$\varphi$$ φ ) and twist pitch on the performance metrics are examined, and the outcomes are compared with those a plain DPHE. The outcomes showed that the increase in Re has desirable effects such as improved heat transfer and heat exchanger effectiveness, and unpleasant effects such as increased pressure drop and pumping power. Moreover, it was found that except for $$\varphi \le 1.5\%$$ φ ≤ 1.5 % and $${\text{Re}} =$$ Re = 500, the NF performs better than the base fluid. In addition, it was reported that the variation pattern of overall hydrothermal performance of NF with twist pitch is ascending–descending. Furthermore, the outcomes illustrated that the overall hydrothermal performance of twisted DPHE is superior to that of the plain DPHE, and its highest value is 2.671, which belongs to case of $${\text{Re}} =$$ Re = 2000, $$\varphi =$$ φ = 3% and twist pitch = 4 mm.
-
Numerical study of the possibility of improving the hydrothermal performance of an elliptical double-pipe heat exchanger through the simultaneous use of twisted tubes and non-Newtonian nanofluid
Journal of Thermal Analysis and Calorimetry, 2020Co-Authors: Amin Shahsavar, Masoud Afrand, Mohammad Amin Bakhshizadeh, Müslüm Arıcı, Sara RostamiAbstract:In this investigation, the combined use of twisted tubes and nanofluid (NF) to augment the performance of a double-pipe heat exchanger (DPHE) has been conSidered numerically. Steady-state laminar flow of the cold non-Newtonian CuO NF and hot water pass inSide the tube Side and Annulus Side, respectively. The base fluid is the aqueous solution of 0.5 mass% carboxymethyl cellulose. The effects of the Reynolds number ( $${\text{Re}}$$ ), the volume concentration of nanoparticles ( $$\varphi$$ ) and twist pitch on the performance metrics are examined, and the outcomes are compared with those a plain DPHE. The outcomes showed that the increase in Re has desirable effects such as improved heat transfer and heat exchanger effectiveness, and unpleasant effects such as increased pressure drop and pumping power. Moreover, it was found that except for $$\varphi \le 1.5\%$$ and $${\text{Re}} =$$ 500, the NF performs better than the base fluid. In addition, it was reported that the variation pattern of overall hydrothermal performance of NF with twist pitch is ascending–descending. Furthermore, the outcomes illustrated that the overall hydrothermal performance of twisted DPHE is superior to that of the plain DPHE, and its highest value is 2.671, which belongs to case of $${\text{Re}} =$$ 2000, $$\varphi =$$ 3% and twist pitch = 4 mm.
-
The effect of inlet temperature on the irreversibility characteristics of non-Newtonian hybrid nano-fluid flow inSide a minichannel counter-current hairpin heat exchanger
Journal of Thermal Analysis and Calorimetry, 2019Co-Authors: Majid Jafari, Boshra Mahmoudi, Azeez A. Barzinjy, Samir M. Hamad, Masoud AfrandAbstract:The goal of this work is to examine the influence of entering temperature on the entropy generation characteristics of a minichannel hairpin heat exchanger with counter-flow configuration. The working fluids are water and hybrid water–Fe3O4/carbon nanotubes (CNTs) nano-fluid (NF) that flows through the Annulus Side and tube Side of the heat exchanger, respectively. It is assumed that the NF is non-Newtonian, and its thermal conductivity and viscosity are temperature dependent. The impact of volume fraction of Fe3O4 ($$\varphi_{\text{FF}}$$) and CNT nanoadditives ($$\varphi_{\text{CNT}}$$) as well as the Reynolds number of NF ($$Re_{\text{nf}}$$) on the Bejan number and irreversibilities due to heat transfer and fluid friction are also assessed. It was found that augmenting the temperature difference between the fluids entering the heat exchanger results in a decrease in the frictional irreversibility and an increase in the global thermal and total irreversibilities and global Bejan number. Additionally, the outcomes depicted that the global frictional and total irreversibilities and the global Bejan number intensify by boosting the $$Re_{\text{nf}}$$ and $$\varphi_{\text{CNT}}$$, while the increase of $$\varphi_{\text{FF}}$$ first leads to the reduction and then the increase of these parameters.
-
Entropy generation of boehmite alumina nanofluid flow through a minichannel heat exchanger conSidering nanoparticle shape effect
Physica A: Statistical Mechanics and its Applications, 2019Co-Authors: Abdullah A.a.a. Al-rashed, Saeed Aghakhani, Masoud Afrand, Ramin Ranjbarzadeh, Mehdi Soltanimehr, Truong Khang NguyenAbstract:Abstract This paper aims to study the effect of nanoparticle shape on the entropy generation characteristics of boehmite alumina nanofluid flowing through a horizontal double-pipe minichannel heat exchanger. Boehmite alumina ( γ -AlOOH) nanoparticles of different shapes (cylindrical, brick, blade, platelet, and spherical) are dispersed in a mixture of water/ethylene glycol as the nanofluid. The nanofluid and water flow in the tube Side and Annulus Side of the heat exchanger, respectively. The effects of the Reynolds number and nanoparticle concentration on the frictional entropy generation rate, thermal entropy generation rate, total entropy generation rate and Bejan number are numerically analyzed for different nanoparticle shapes. The obtained results demonstrated that the nanofluids containing platelet shape and spherical shape nanoparticles have the highest and lowest rates of thermal, frictional, and total entropy generation, respectively. Additionally, it was found that the rates of thermal, frictional, and total entropy generation increase with an increase in the Reynolds number, while the opposite is true for the Bejan number. Furthermore, it was inferred from the obtained results that the increase of nanoparticle concentration results in higher frictional and total entropy generation rates and lower Bejan number.
-
Laminar forced convection performance of non-Newtonian water-CNT/Fe3O4 nano-fluid inSide a minichannel hairpin heat exchanger: Effect of inlet temperature
Powder Technology, 2019Co-Authors: W.i. Liu, Abdullah A.a.a. Al-rashed, Amin Shahsavar, Ali Sulaiman Alsagri, Boshra Mahmoudi, Masoud AfrandAbstract:Abstract This numerical study aims to focus on the effect of difference between the inlet temperatures of working fluids on the hydrothermal characteristics of a counter-current minichannel hairpin heat exchanger. The water flows in the Annulus Side and the water based hybrid nano-fluid containing Fe3O4 and carbon nanotubes (CNTs) passes through the tube Side of heat exchanger. Temperature-dependent thermal conductivity and viscosity are conSidered for the non-Newtonian hybrid nano-fluid. The effects of Fe3O4 and CNT volume fractions as well as the Reynolds number on the performance metrics of the heat exchanger are also assessed. The results revealed that the increase of difference between the inlet temperatures of working fluids leads to the augmentation of heat transfer rate, overall heat transfer coefficient (except at Reynolds number of 500), heat exchanger effectiveness and PEC; while the pumping power diminishes with the increase of inlet water temperature.