Navid Bagheri - Academia.edu (original) (raw)
Papers by Navid Bagheri
Journal of Molecular Liquids, Oct 1, 2022
Entropy
The authors wish to make the following correction to this paper [...]
International Journal of Thermal Sciences, 2020
Abstract Baseboard heaters are a type of building heating systems that are placed along the base ... more Abstract Baseboard heaters are a type of building heating systems that are placed along the base of the interior wall, instead of the traditional skirting. Baseboard heaters meet all the requirements of modern buildings such as thermal comfort, well-architected appearance, space-saving, efficient energy consumption, and fast thermal response. In the present study, we investigate the enhancement of the thermal output of hydronic baseboard heaters. For this purpose, several novel fin-tube arrays such as convector fins and fin-clips are proposed and the thermal performance of each array is evaluated experimentally. In addition, two different types of materials for the tubes, namely, copper and aluminum are examined during the experiment. The computational fluid dynamic simulations are used to carefully analyze the mechanism of the heat transfer enhancement in the baseboard heaters. The results indicate that the novel fins may considerably increase the performance. For instance, for low and high water temperatures, the convector fins can increase the performance by up to 42% and 94%, respectively, compared to the conventional fins. A baseboard heater with a convector fin and a copper tube exhibits the highest performance.
Journal of Molecular Liquids, 2019
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
International Journal of Numerical Methods for Heat & Fluid Flow, 2019
Purpose The nanofluid flow and heat transfer within a heat exchanger, with different thermal arra... more Purpose The nanofluid flow and heat transfer within a heat exchanger, with different thermal arrangements of internal active bodies, are investigated. Design/methodology/approach For the numerical simulations, the lattice Boltzmann method is utilized. The KKL model is used to predict the dynamic viscosity of CuO-water nanofluid. Furthermore, the Brownian method is taken account using this model. The influence of shapes of nanoparticles on the heat transfer performance is considered. Findings The results show that the platelet nanoparticles render higher average Nusselt number showing better heat transfer performance. In order to perform comprehensive analysis, the heatline visualization, local and total entropy generation, local and average Nusselt variation are employed. Originality/value The originality of this work is carrying out a comprehensive investigation of nanofluid flow and heat transfer during natural convection using lattice Boltzmann method and employing second law ana...
Chinese Journal of Physics, 2019
The numerical modelling of natural convection fluid flow and heat transfer in a quarter of gearwh... more The numerical modelling of natural convection fluid flow and heat transfer in a quarter of gearwheel-shaped heat exchanger is carried out. The heat exchanger is included with internal active square bodies. These bodies have hot and cold temperatures with different thermal arrangements. Three different thermal arrangements are considered and showed with Case A, Case B and Case C. The CuO-water nanofluid is selected as operating fluid. The Koo-Kleinstreuer-Li (KKL) correlation is utilized to estimate the dynamic viscosity and thermal conductivity. In addition, the shapes of nanoparticles are taken account in the analysis. The Rayleigh number, nanoparticle concentration and thermal arrangements of internal active bodies are the governing parameters. The impacts of these parameters on the fluid flow, heat transfer rate, local and total entropy generation and heatlines are studied, comprehensively. The results show that the heat transfer rate enhances with increasing of Rayleigh number and nanoparticle concentration. Moreover, the thermal arrangement of internal active bodies has considerable effect on the heat transfer between heat sources and heat sinks. On the other hand, the total entropy generation enhances and decreases with increasing of Rayleigh number and nanoparticle concentration, respectively.
International Journal of Numerical Methods for Heat & Fluid Flow, 2018
PurposeThis paper aims to investigate the two-dimensional numerical modeling of fluid flow and he... more PurposeThis paper aims to investigate the two-dimensional numerical modeling of fluid flow and heat transfer in a fluid channel.Design/methodology/approachThe channel is filled with the CuO-water nanofluid. The KKL model is used to estimate the dynamic viscosity and considering Brownian motion. On the other hand, the influence of CuO nanoparticles’ shapes on the heat transfer rate is taken account in the simulations. The channel is included with several active pipes with hot and cold temperatures. Furthermore, the external curved and sinusoidal walls have cold and hot temperatures, respectively.FindingsThree different tilt angles are considered with similar boundary and operating conditions. The Rayleigh numbers, solid volume fraction of CuO nanoparticles in the pure water and the tilt angles are the governing parameters. Different cases studies, such as streamlines, heat transfer rate, local and total entropy generation and heatlines, are analysed under influences of these governin...
Applied Thermal Engineering, 2017
This paper deals with laminar forced convection of Al2O3-water nanofluid in developing region of ... more This paper deals with laminar forced convection of Al2O3-water nanofluid in developing region of a channel with staggered baffles considering thermophoresis and Brownian motion. An extra scalar equation is considered along with other conservation equations to determine the dispersed nanoparticles distribution throughout the channel. The effect of nanoparticle concentration, Reynolds number and baffle height on the velocity and temperature fields, heat transfer rate, pressure drop and hydrothermal performance of the baffled channel is numerically investigated and the contours of nanoparticle distribution provided. The presence of nanoparticles results in a significant reduction in wall temperature, especially in dead regions in which hot spots are generated. Nanoparticle concentration decreases in recirculation regions and a wavy layer of the agglomerated nanoparticle is shaped exactly over the baffles. With decreasing Reynolds number, more non-uniform nanoparticle distribution is observed in baffled channel and the effect of nanofluid on temperature reduction becomes more pronounced. By addition nanoparticle into basefluid, the length and strength of recirculation flow decreases. Nanoparticles are of more significant effect on heat transfer enhancement and pressure drop increment when nanoparticle concentration and Reynolds number, respectively, rises and declines. The baffled channel presents a better hydrothermal performance for lower nanoparticle concentration and Reynolds number. As the baffle height is raised, more uniformity of nanoparticle distribution is observed in baffled channel and the influence of nanofluid on the wall temperature reduction in recirculation regions and reattachment points, respectively, increases and decreases. The computational results reveal that the impact of nanofluid on heat transfer and pressure drop augmentation depends on baffle height and an optimum value exists providing the best hydrothermal performance for baffled channel.
Entropy, 2017
Numerical investigation of the effects of magnetic field strength, thermal radiation, Joule heati... more Numerical investigation of the effects of magnetic field strength, thermal radiation, Joule heating, and viscous heating on a forced convective flow of a non-Newtonian, incompressible power law fluid in an axisymmetric stretching sheet with variable temperature wall is accomplished. The power law shear thinning viscosity-shear rate model for the anisotropic solutions and the Rosseland approximation for the thermal radiation through a highly absorbing medium are considered. The temperature dependent heat sources, Joule heating, and viscous heating are considered as the source terms in the energy balance. The non-dimensional boundary layer equations are solved numerically in terms of similarity variable. A parameter study on the Nusselt number, viscous components of entropy generation, and thermal components of entropy generation in fluid is performed as a function of thermal radiation parameter (0 to 2), Brinkman number (0 to 10), Prandtl number (0 to 10), Hartmann number (0 to 1), power law index (0 to 1), and heat source coefficient (0 to 0.1).
Advances in environmental research, 2015
This article outlines a case study of water and energy savings in a typical building through a mo... more This article outlines a case study of water and energy savings in a typical building through a modelling process and analysis of simultaneous water-energy saving measures. Wet cooling towers are one of the most important equipments in buildings with a considerable amount of water and energy consumption. A variety of methods are provided to reduce water and energy consumption in these facilities. In this paper, thorough the modeling of a typical building, water and energy consumption are measured. Then, After application of modern methods known to be effective in saving water and energy, including the ozone treatment for cooling towers and shade installation for windows, i.e. fins and overhangs, the amount of water and energy saving are compared with the base case using the Simergy model. The annual water consumption of the building, by more than 50% reduction, has been reached to 500 cubic meters from 1024 cubic meters. The annual electric energy consumption has been decreased from 405,178 kWh to 340,944 kWh, which is about 16%. After modeling, monthly peak of electrical energy consumption of 49,428 has dropped to 40,562 kWh. The reduction of 18% in the monthly peak can largely reduce the expenses of electricity consumption at peak.
Entropy, 2016
Numerical study of the slip effects and radiative heat transfer on a steady state fully developed... more Numerical study of the slip effects and radiative heat transfer on a steady state fully developed Williamson flow of an incompressible Newtonian fluid; between parallel vertical walls of a microchannel with isothermal walls in a porous medium is performed. The slip effects are considered at both boundary conditions. Radiative highly absorbing medium is modeled by the Rosseland approximation. The non-dimensional governing Navier-Stokes and energy coupled partial differential equations formed a boundary problem are solved numerically using the fourth order Runge-Kutta algorithm by means of a shooting method. Numerical outcomes for the skin friction coefficient, the rate of heat transfer represented by the local Nusselt number were presented even as the velocity and temperature profiles illustrated graphically and analyzed. The effects of the temperature number, Grashof number, thermal radiation parameter, Reynolds number, velocity slip length, Darcy number, and temperature jump, on the flow field and temperature field and their effects on the boundaries are presented and discussed.
Journal of separation science, Jan 23, 2016
A magnetic solid-phase extraction method coupled with gas chromatography was proposed for the det... more A magnetic solid-phase extraction method coupled with gas chromatography was proposed for the determination of polycyclic aromatic hydrocarbons in the environmental water samples. The magnetic adsorbent was prepared by incorporating Fe3 O4 nanoparticles, multi-walled carbon nanotubes and polypyrrole. The main factors affecting the extraction efficiency including the amount of the sorbents, desorption conditions, extraction time, salt concentration and sample solution pH were investigated and optimized. Under the optimum conditions, good linearity was obtained within the range of 0.03-100 ng mL(-1) for all analytes, with correlation coefficients ranging from 0.9942 to 0.9973. The method detection limits (S/N = 3) were in the range of 0.01-0.04 ng mL(-1) and the limits of quantification (S/N = 10) were 0.03-0.1 ng mL(-1) . Repeatability of the method was assessed through five consecutive extractions of independently prepared solutions at concentrations of 0.1, 10, and 100 ng mL(-1) of...
International Journal of Mathematics Trends and Technology, 2018
Uncertainty can be expressed by fuzzy numbers. Some fuzzy numbers are triangular and trapezoidal.... more Uncertainty can be expressed by fuzzy numbers. Some fuzzy numbers are triangular and trapezoidal. Although it is easy to perform calculations on them, they are not flexible enough to show the uncertainty. Bell shape fuzzy numbers are very flexible. However, it is very difficult to conduct arithmetic operations on them. In this paper, a new bell shape fuzzy number has been developed. The new fuzzy number looks like a bell. Then, arithmetic operations have been defined for the new fuzzy number. Also, it has been proven that the ranking of the new fuzzy number can be done successfully. The above mentioned opera tions and the ranking method o f t h e new fuzzy number have been described by some examples. The new fuzzy number is more flexible compared to triangular and trapezoidal ones. Also, arithmetic calculation of the new fuzzy number is much simpler than t h a t of a bell shape fuzzy number.
Journal of Molecular Liquids, Oct 1, 2022
Entropy
The authors wish to make the following correction to this paper [...]
International Journal of Thermal Sciences, 2020
Abstract Baseboard heaters are a type of building heating systems that are placed along the base ... more Abstract Baseboard heaters are a type of building heating systems that are placed along the base of the interior wall, instead of the traditional skirting. Baseboard heaters meet all the requirements of modern buildings such as thermal comfort, well-architected appearance, space-saving, efficient energy consumption, and fast thermal response. In the present study, we investigate the enhancement of the thermal output of hydronic baseboard heaters. For this purpose, several novel fin-tube arrays such as convector fins and fin-clips are proposed and the thermal performance of each array is evaluated experimentally. In addition, two different types of materials for the tubes, namely, copper and aluminum are examined during the experiment. The computational fluid dynamic simulations are used to carefully analyze the mechanism of the heat transfer enhancement in the baseboard heaters. The results indicate that the novel fins may considerably increase the performance. For instance, for low and high water temperatures, the convector fins can increase the performance by up to 42% and 94%, respectively, compared to the conventional fins. A baseboard heater with a convector fin and a copper tube exhibits the highest performance.
Journal of Molecular Liquids, 2019
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
International Journal of Numerical Methods for Heat & Fluid Flow, 2019
Purpose The nanofluid flow and heat transfer within a heat exchanger, with different thermal arra... more Purpose The nanofluid flow and heat transfer within a heat exchanger, with different thermal arrangements of internal active bodies, are investigated. Design/methodology/approach For the numerical simulations, the lattice Boltzmann method is utilized. The KKL model is used to predict the dynamic viscosity of CuO-water nanofluid. Furthermore, the Brownian method is taken account using this model. The influence of shapes of nanoparticles on the heat transfer performance is considered. Findings The results show that the platelet nanoparticles render higher average Nusselt number showing better heat transfer performance. In order to perform comprehensive analysis, the heatline visualization, local and total entropy generation, local and average Nusselt variation are employed. Originality/value The originality of this work is carrying out a comprehensive investigation of nanofluid flow and heat transfer during natural convection using lattice Boltzmann method and employing second law ana...
Chinese Journal of Physics, 2019
The numerical modelling of natural convection fluid flow and heat transfer in a quarter of gearwh... more The numerical modelling of natural convection fluid flow and heat transfer in a quarter of gearwheel-shaped heat exchanger is carried out. The heat exchanger is included with internal active square bodies. These bodies have hot and cold temperatures with different thermal arrangements. Three different thermal arrangements are considered and showed with Case A, Case B and Case C. The CuO-water nanofluid is selected as operating fluid. The Koo-Kleinstreuer-Li (KKL) correlation is utilized to estimate the dynamic viscosity and thermal conductivity. In addition, the shapes of nanoparticles are taken account in the analysis. The Rayleigh number, nanoparticle concentration and thermal arrangements of internal active bodies are the governing parameters. The impacts of these parameters on the fluid flow, heat transfer rate, local and total entropy generation and heatlines are studied, comprehensively. The results show that the heat transfer rate enhances with increasing of Rayleigh number and nanoparticle concentration. Moreover, the thermal arrangement of internal active bodies has considerable effect on the heat transfer between heat sources and heat sinks. On the other hand, the total entropy generation enhances and decreases with increasing of Rayleigh number and nanoparticle concentration, respectively.
International Journal of Numerical Methods for Heat & Fluid Flow, 2018
PurposeThis paper aims to investigate the two-dimensional numerical modeling of fluid flow and he... more PurposeThis paper aims to investigate the two-dimensional numerical modeling of fluid flow and heat transfer in a fluid channel.Design/methodology/approachThe channel is filled with the CuO-water nanofluid. The KKL model is used to estimate the dynamic viscosity and considering Brownian motion. On the other hand, the influence of CuO nanoparticles’ shapes on the heat transfer rate is taken account in the simulations. The channel is included with several active pipes with hot and cold temperatures. Furthermore, the external curved and sinusoidal walls have cold and hot temperatures, respectively.FindingsThree different tilt angles are considered with similar boundary and operating conditions. The Rayleigh numbers, solid volume fraction of CuO nanoparticles in the pure water and the tilt angles are the governing parameters. Different cases studies, such as streamlines, heat transfer rate, local and total entropy generation and heatlines, are analysed under influences of these governin...
Applied Thermal Engineering, 2017
This paper deals with laminar forced convection of Al2O3-water nanofluid in developing region of ... more This paper deals with laminar forced convection of Al2O3-water nanofluid in developing region of a channel with staggered baffles considering thermophoresis and Brownian motion. An extra scalar equation is considered along with other conservation equations to determine the dispersed nanoparticles distribution throughout the channel. The effect of nanoparticle concentration, Reynolds number and baffle height on the velocity and temperature fields, heat transfer rate, pressure drop and hydrothermal performance of the baffled channel is numerically investigated and the contours of nanoparticle distribution provided. The presence of nanoparticles results in a significant reduction in wall temperature, especially in dead regions in which hot spots are generated. Nanoparticle concentration decreases in recirculation regions and a wavy layer of the agglomerated nanoparticle is shaped exactly over the baffles. With decreasing Reynolds number, more non-uniform nanoparticle distribution is observed in baffled channel and the effect of nanofluid on temperature reduction becomes more pronounced. By addition nanoparticle into basefluid, the length and strength of recirculation flow decreases. Nanoparticles are of more significant effect on heat transfer enhancement and pressure drop increment when nanoparticle concentration and Reynolds number, respectively, rises and declines. The baffled channel presents a better hydrothermal performance for lower nanoparticle concentration and Reynolds number. As the baffle height is raised, more uniformity of nanoparticle distribution is observed in baffled channel and the influence of nanofluid on the wall temperature reduction in recirculation regions and reattachment points, respectively, increases and decreases. The computational results reveal that the impact of nanofluid on heat transfer and pressure drop augmentation depends on baffle height and an optimum value exists providing the best hydrothermal performance for baffled channel.
Entropy, 2017
Numerical investigation of the effects of magnetic field strength, thermal radiation, Joule heati... more Numerical investigation of the effects of magnetic field strength, thermal radiation, Joule heating, and viscous heating on a forced convective flow of a non-Newtonian, incompressible power law fluid in an axisymmetric stretching sheet with variable temperature wall is accomplished. The power law shear thinning viscosity-shear rate model for the anisotropic solutions and the Rosseland approximation for the thermal radiation through a highly absorbing medium are considered. The temperature dependent heat sources, Joule heating, and viscous heating are considered as the source terms in the energy balance. The non-dimensional boundary layer equations are solved numerically in terms of similarity variable. A parameter study on the Nusselt number, viscous components of entropy generation, and thermal components of entropy generation in fluid is performed as a function of thermal radiation parameter (0 to 2), Brinkman number (0 to 10), Prandtl number (0 to 10), Hartmann number (0 to 1), power law index (0 to 1), and heat source coefficient (0 to 0.1).
Advances in environmental research, 2015
This article outlines a case study of water and energy savings in a typical building through a mo... more This article outlines a case study of water and energy savings in a typical building through a modelling process and analysis of simultaneous water-energy saving measures. Wet cooling towers are one of the most important equipments in buildings with a considerable amount of water and energy consumption. A variety of methods are provided to reduce water and energy consumption in these facilities. In this paper, thorough the modeling of a typical building, water and energy consumption are measured. Then, After application of modern methods known to be effective in saving water and energy, including the ozone treatment for cooling towers and shade installation for windows, i.e. fins and overhangs, the amount of water and energy saving are compared with the base case using the Simergy model. The annual water consumption of the building, by more than 50% reduction, has been reached to 500 cubic meters from 1024 cubic meters. The annual electric energy consumption has been decreased from 405,178 kWh to 340,944 kWh, which is about 16%. After modeling, monthly peak of electrical energy consumption of 49,428 has dropped to 40,562 kWh. The reduction of 18% in the monthly peak can largely reduce the expenses of electricity consumption at peak.
Entropy, 2016
Numerical study of the slip effects and radiative heat transfer on a steady state fully developed... more Numerical study of the slip effects and radiative heat transfer on a steady state fully developed Williamson flow of an incompressible Newtonian fluid; between parallel vertical walls of a microchannel with isothermal walls in a porous medium is performed. The slip effects are considered at both boundary conditions. Radiative highly absorbing medium is modeled by the Rosseland approximation. The non-dimensional governing Navier-Stokes and energy coupled partial differential equations formed a boundary problem are solved numerically using the fourth order Runge-Kutta algorithm by means of a shooting method. Numerical outcomes for the skin friction coefficient, the rate of heat transfer represented by the local Nusselt number were presented even as the velocity and temperature profiles illustrated graphically and analyzed. The effects of the temperature number, Grashof number, thermal radiation parameter, Reynolds number, velocity slip length, Darcy number, and temperature jump, on the flow field and temperature field and their effects on the boundaries are presented and discussed.
Journal of separation science, Jan 23, 2016
A magnetic solid-phase extraction method coupled with gas chromatography was proposed for the det... more A magnetic solid-phase extraction method coupled with gas chromatography was proposed for the determination of polycyclic aromatic hydrocarbons in the environmental water samples. The magnetic adsorbent was prepared by incorporating Fe3 O4 nanoparticles, multi-walled carbon nanotubes and polypyrrole. The main factors affecting the extraction efficiency including the amount of the sorbents, desorption conditions, extraction time, salt concentration and sample solution pH were investigated and optimized. Under the optimum conditions, good linearity was obtained within the range of 0.03-100 ng mL(-1) for all analytes, with correlation coefficients ranging from 0.9942 to 0.9973. The method detection limits (S/N = 3) were in the range of 0.01-0.04 ng mL(-1) and the limits of quantification (S/N = 10) were 0.03-0.1 ng mL(-1) . Repeatability of the method was assessed through five consecutive extractions of independently prepared solutions at concentrations of 0.1, 10, and 100 ng mL(-1) of...
International Journal of Mathematics Trends and Technology, 2018
Uncertainty can be expressed by fuzzy numbers. Some fuzzy numbers are triangular and trapezoidal.... more Uncertainty can be expressed by fuzzy numbers. Some fuzzy numbers are triangular and trapezoidal. Although it is easy to perform calculations on them, they are not flexible enough to show the uncertainty. Bell shape fuzzy numbers are very flexible. However, it is very difficult to conduct arithmetic operations on them. In this paper, a new bell shape fuzzy number has been developed. The new fuzzy number looks like a bell. Then, arithmetic operations have been defined for the new fuzzy number. Also, it has been proven that the ranking of the new fuzzy number can be done successfully. The above mentioned opera tions and the ranking method o f t h e new fuzzy number have been described by some examples. The new fuzzy number is more flexible compared to triangular and trapezoidal ones. Also, arithmetic calculation of the new fuzzy number is much simpler than t h a t of a bell shape fuzzy number.