vali kalantar - Academia.edu (original) (raw)

Papers by vali kalantar

Heat transfer research, 2023

An experimental investigation to a novel MPCM slurry based PV/T system was conducted. The system ... more An experimental investigation to a novel MPCM slurry based PV/T system was conducted. The system had the reduced solar efficiency at a higher solar radiation. The system had the increased solar efficiency at a higher slurry Reynolds number. The most favourite MPCM concentration was around 10%. The experimental results approved the accuracy of the established computer model.

This paper presents a numerical investigation of the mixing performance of two hybrid passiveacti... more This paper presents a numerical investigation of the mixing performance of two hybrid passiveactive micromixers subjected to an acoustic field. The study employs the Generalized Lagrangian Mean (GLM) theory and the convection-diffusion equation to analyze concentration profiles within the micromixers, providing a comprehensive assessment of their performance. Perturbation theory is employed to solve the equations of zeroth-, first-, and second-order, resulting in the determination of the final flow velocity from the zeroth-and second-order solutions. Notably, the study incorporates a non-zero background laminar flow to explore the interaction between acoustic waves and a moving laminar flow. The findings reveal that while the presence of sharp-edge structures on the channel walls significantly enhances mixing quality, this improvement is not observed that much when rectangular structures.

Modares Mechanical Engineering, Jun 10, 2020

Chemical Engineering and Processing, Sep 1, 2023

Modares Mechanical Engineering, Oct 10, 2019

Increasing the viscosity of injected water by the addition of polymer improves the displacement e... more Increasing the viscosity of injected water by the addition of polymer improves the displacement efficiency during the water flooding process. In this study, a sulfonated polyacrylamide copolymer has been added to salt water. Several parameters, such as polymer concentration, shear rate, NaCl concentration, molecular weight and sulfonation degree, have a significant effect on the polymer solution viscosity. The main objective of this paper is to investigate how the polymer solution viscosity varies with changes in the input parameters so as to identify the relative importance of these parameters. This paper incorporates the Design of Experiments technique using Taguchi's method and the Analysis of Variance (ANOVA) to investigate the effect of process variables on the viscosity of a polymer solution. Five input parameters and six possible interactions have been investigated. The analysis of the experimental results revealed that two input parameters, namely, polymer concentration and shear rate, have the most significant impact on polymer viscosity. Two strong interactions were observed in the (1) NaCl concentration and sulfonation degree and (2) molecular weight and NaCl concentration studies. The results show that the Taguchi method was successful in identifying the main effects and interaction effects. ANOVA further buttresses the results from Taguchi's method by showing a strong similarity in its results.

مواد و فناوری های پیشرفته, Oct 23, 2009

In the present study, an attempt is made to study the cooling performance of a wind tower and a s... more In the present study, an attempt is made to study the cooling performance of a wind tower and a solar chimney in a hot and dry region.Also in this study the effects of parameters including wind tower height, variety of the materials used in the wind tower walls, the amount of vaporized water, the temperature of input and output air, the wind velocity and the relative humidity were investigated. Furthermore, to develop, a natural flow of air, for days without blowing a wind the role of solar chimney was considered.Finally, to investigate and take information about streamlines of airflow in wind tower (Baud-Geer), velocity, pressure, humidity, temperature and density profile of fluid, Fluent software is applied to evaluate the air flow in the wind tower in differential view for two dimensional and steady state conditions with water spraying at the top of wind tower. The results indicate that the evaporative cooling is very effective in a hot and dry region. The temperature decreases considerably, if the wind towers are equipped with the water vaporization system. This causes the air becomes heavier and a natural motion of air through downside of wind tower to be produced.

Applied Energy, 2016

Based on the theoretical works completed by the authors, the paper presents an experimental inves... more Based on the theoretical works completed by the authors, the paper presents an experimental investigation into the energy performance of a novel PV/T thermal and power system that employs the Micro-encapsulated Phase Change Material (MPCM) slurry as the working fluid. A prototype PV/T module with the dimension of 800 mm × 1600 mm × 50mm was designed and constructed based on previous theoretical modelling data. The performance of the PV/T module and associated thermal and power system were tested under various solar radiations, slurry Reynolds numbers and MPCM concentrations. It was found that (1) increasing solar radiation led to the increased PV/T module temperature, decreased solar thermal & electrical efficiencies and reduced slurry pressure drop; (2) increasing the slurry Reynolds number led to the increased solar thermal & electrical efficiencies, decreased module temperature, and increased pressure drop; and (3) increasing the MPCM concentration led to the reduced module temperature and increased pressure drop. The experimental results were used to examine the accuracy of the established computer model, giving a derivation rate in the range 1.1% to 6.1% which is an acceptable error level for general engineering simulation. The optimum operational condition and performance of the PV/T system could be outlined in such way: MPCM slurry weight concentration of 10%, Reynolds number of 3,000, solar radiation of 500 W/m 2 to 700 W/m 2 , and the net overall solar efficiencies in the range 80.8% to 83.9%. To summarise, the MPCM slurry based PV/T thermal and power system is superior to conventional air-sourced heat pump systems (ASHP) and solar assisted heat pump systems (ISAHP), and has the potential to help reduce fossil fuel consumption and carbon emission to the environment.

In this experimental study, the forced convection heat transfer of thermally developing Fe2O3/wat... more In this experimental study, the forced convection heat transfer of thermally developing Fe2O3/water nanoparticles inside a copper tube under magnetic field created by a number of permanent flat magnets is investigated. Experiments have been carried out under laminar flow regime and uniform heat flux boundary condition and the influence of magnetic field position and intensity. The objectives of this study were to investigate the effect of using Fe2O3/water nanofluid, flow Reynolds number, intensity and magnetic field position on the thermal behavior of the flow. Validation of the test apparatus was performed using distilled water and compared with the theoretical results, which eventually achieved good agreement. The results show that due to the influence of the magnetic field on the Fe2O3/water nanofluid, secondary flow and boundary layer deformation occur, the heat transfer changes and its variation is dependent on the flow profile and intensity and position of the magnetic field....

ARTICLE INFORMATION ABSTRACT Original Research Paper Received 03 July 2016 Accepted 18 September ... more ARTICLE INFORMATION ABSTRACT Original Research Paper Received 03 July 2016 Accepted 18 September 2016 Available Online 09 October 2016 Accurate measurement of unsteady pressure fluctuations along a surface requires experimental set up with high spacing resolution and high frequency domain. Therefore, in recent decades extensive studies have been conducted on remote microphone approach. In this method, instead of using flash mounted sensors, they were installed remotely and connected to the model surface through one or several continuously connected tubes. Surface pressure fluctuations travel within the tubing in the form of sound waves and they are measured when passing over the remote pressure sensor, mounted perpendicular to the tubing. In the present study, an analytical solution of sound waves propagation inside the rigid tubes is used for modelling of the remote microphone system and to investigate the effects of its parameters on dynamic response. In order to verify the accura...

Advanced Powder Technology

Journal of Thermal Analysis and Calorimetry

International Journal of Nano Dimension, Jan 12, 2015

In this research, some more applicable ferrofluids are produced and their mechanical specificatio... more In this research, some more applicable ferrofluids are produced and their mechanical specifications are measured, experimentally. Also, their treatments in the ventilated cavity geometry are assessed numerically. The magnetite nanoparticles are produced by a chemical combination of Fe 2+ and Fe 3+ with NH 3. In order to solve the nanoparticles in the new mediums, a proper coating is added to them. Then they are solved in kerosene, brake oil, hydraulic oil and motor oil with different particle fractures. A pressure-based procedure to solve Navier-stokes equations with finite volume formulation is developed to simulate a magnetic fluid in ventilated cavity geometry. One of the usages of this geometry is found in magnetic separation. The ventilated cavity geometry includes a square medium with one velocity inlet and one velocity outlet. In addition, a magnetic field due to a DC current carrying wire is employed on the geometry. The magnetic field intensities, its positions and ferrofluids' mediums are changed. Then, the flow characteristics for each case are obtained to find the optimum situation for magnetic separation. Finally, the optimum situations for magnetic separation and for local cooling are obtained and the best ferrofluid is suggested for each application.

In this research, some more applicable ferrofluids are produced and their mechanical specificatio... more In this research, some more applicable ferrofluids are produced and their mechanical specifications are measured, experimentally. Also, their treatments in the ventilated cavity geometry are assessed numerically. The magnetite nanoparticles are produced by a chemical combination of Fe2+ and Fe3+ with NH3. In order to solve the nanoparticles in the new mediums, a proper coating is added to them. Then they are solved in kerosene, brake oil, hydraulic oil and motor oil with different particle fractures. A pressure-based procedure to solve Navier-stokes equations with finite volume formulation is developed to simulate a magnetic fluid in ventilated cavity geometry. One of the usages of this geometry is found in magnetic separation. The ventilated cavity geometry includes a square medium with one velocity inlet and one velocity outlet. In addition, a magnetic field due to a DC current carrying wire is employed on the geometry. The magnetic field intensities, its positions and ferrofluids...

Since the electricity and the other modern energy sources had not been developed in the past, hum... more Since the electricity and the other modern energy sources had not been developed in the past, human being inevitably was trying to find ways to provide comfort of living. One of these cases is Baad-Gir which since a long time ago has been used and appreciated by the general public in hot and dry climate zones dwellers. Now, in addition to growing tendency of researchers to use renewable energy, they are more than willing to improve performance of traditional methods. In the present work, a method has been proposed and investigated to provide room air based on using underground channel. Since the subsurface soil temperature is much lower than the surface and due to the large volume of soil, it can be considered and used as a heat sink, without any costs and power consumption. In this work, two channels are considered, dry one which is modeled according to soil temperature and the other wet one, via using Ghanat or by adding water manually. Results are compared and it is concluded tha...

Climate change, global warming, and the recent worldwide economic crisis have emphasized the need... more Climate change, global warming, and the recent worldwide economic crisis have emphasized the need for low carbon emissions while also ensuring economic feasibility. In this paper, the status and wind power potential of the city of Shahrbabak in Kerman province in Iran was investigated. The technical and economical feasibility of wind turbine installation is presented. The potential of wind power generation was statistically analyzed. The mean wind speed data of three-hour interval long term period from 1997 to 2005 was adopted and analyzed in order to determine the potential of wind power generation. The numerical values of the dimensionless Weibull shape parameter (k) and Weibull scale parameter (c) were determined. Annual values of "k" ranged from 1.725 to 1.930 with a mean value of 1.504, while annual values of "c" were in the range of 4.848-6.095 with a mean value of 5.314 (m/s). With the average wind power density of 100 W/m 2 , it is found that the city is not an appropriate place for construction of large-scale wind power plants, but is suitable for employment of off-grid electrical and mechanical wind driven systems. An economic evaluation was done in order to show feasibility of installing small wind turbines. It was concluded that it costs 18 cents for 1 kW h which is 5 cents more than the market price. Each turbine of 10 kW can supply power for icebox, washer, water pump, TV, lighting, electrical fan, charger, and air conditioning units for small houses. In order to utilize wind energy in the region, it is recommended to install small size wind turbines for electricity supply of public and public buildings and private houses.

International Journal of Design & Nature and Ecodynamics

Heat transfer research, 2023

An experimental investigation to a novel MPCM slurry based PV/T system was conducted. The system ... more An experimental investigation to a novel MPCM slurry based PV/T system was conducted. The system had the reduced solar efficiency at a higher solar radiation. The system had the increased solar efficiency at a higher slurry Reynolds number. The most favourite MPCM concentration was around 10%. The experimental results approved the accuracy of the established computer model.

This paper presents a numerical investigation of the mixing performance of two hybrid passiveacti... more This paper presents a numerical investigation of the mixing performance of two hybrid passiveactive micromixers subjected to an acoustic field. The study employs the Generalized Lagrangian Mean (GLM) theory and the convection-diffusion equation to analyze concentration profiles within the micromixers, providing a comprehensive assessment of their performance. Perturbation theory is employed to solve the equations of zeroth-, first-, and second-order, resulting in the determination of the final flow velocity from the zeroth-and second-order solutions. Notably, the study incorporates a non-zero background laminar flow to explore the interaction between acoustic waves and a moving laminar flow. The findings reveal that while the presence of sharp-edge structures on the channel walls significantly enhances mixing quality, this improvement is not observed that much when rectangular structures.

Modares Mechanical Engineering, Jun 10, 2020

Chemical Engineering and Processing, Sep 1, 2023

Modares Mechanical Engineering, Oct 10, 2019

Increasing the viscosity of injected water by the addition of polymer improves the displacement e... more Increasing the viscosity of injected water by the addition of polymer improves the displacement efficiency during the water flooding process. In this study, a sulfonated polyacrylamide copolymer has been added to salt water. Several parameters, such as polymer concentration, shear rate, NaCl concentration, molecular weight and sulfonation degree, have a significant effect on the polymer solution viscosity. The main objective of this paper is to investigate how the polymer solution viscosity varies with changes in the input parameters so as to identify the relative importance of these parameters. This paper incorporates the Design of Experiments technique using Taguchi's method and the Analysis of Variance (ANOVA) to investigate the effect of process variables on the viscosity of a polymer solution. Five input parameters and six possible interactions have been investigated. The analysis of the experimental results revealed that two input parameters, namely, polymer concentration and shear rate, have the most significant impact on polymer viscosity. Two strong interactions were observed in the (1) NaCl concentration and sulfonation degree and (2) molecular weight and NaCl concentration studies. The results show that the Taguchi method was successful in identifying the main effects and interaction effects. ANOVA further buttresses the results from Taguchi's method by showing a strong similarity in its results.

مواد و فناوری های پیشرفته, Oct 23, 2009

In the present study, an attempt is made to study the cooling performance of a wind tower and a s... more In the present study, an attempt is made to study the cooling performance of a wind tower and a solar chimney in a hot and dry region.Also in this study the effects of parameters including wind tower height, variety of the materials used in the wind tower walls, the amount of vaporized water, the temperature of input and output air, the wind velocity and the relative humidity were investigated. Furthermore, to develop, a natural flow of air, for days without blowing a wind the role of solar chimney was considered.Finally, to investigate and take information about streamlines of airflow in wind tower (Baud-Geer), velocity, pressure, humidity, temperature and density profile of fluid, Fluent software is applied to evaluate the air flow in the wind tower in differential view for two dimensional and steady state conditions with water spraying at the top of wind tower. The results indicate that the evaporative cooling is very effective in a hot and dry region. The temperature decreases considerably, if the wind towers are equipped with the water vaporization system. This causes the air becomes heavier and a natural motion of air through downside of wind tower to be produced.

Applied Energy, 2016

Based on the theoretical works completed by the authors, the paper presents an experimental inves... more Based on the theoretical works completed by the authors, the paper presents an experimental investigation into the energy performance of a novel PV/T thermal and power system that employs the Micro-encapsulated Phase Change Material (MPCM) slurry as the working fluid. A prototype PV/T module with the dimension of 800 mm × 1600 mm × 50mm was designed and constructed based on previous theoretical modelling data. The performance of the PV/T module and associated thermal and power system were tested under various solar radiations, slurry Reynolds numbers and MPCM concentrations. It was found that (1) increasing solar radiation led to the increased PV/T module temperature, decreased solar thermal & electrical efficiencies and reduced slurry pressure drop; (2) increasing the slurry Reynolds number led to the increased solar thermal & electrical efficiencies, decreased module temperature, and increased pressure drop; and (3) increasing the MPCM concentration led to the reduced module temperature and increased pressure drop. The experimental results were used to examine the accuracy of the established computer model, giving a derivation rate in the range 1.1% to 6.1% which is an acceptable error level for general engineering simulation. The optimum operational condition and performance of the PV/T system could be outlined in such way: MPCM slurry weight concentration of 10%, Reynolds number of 3,000, solar radiation of 500 W/m 2 to 700 W/m 2 , and the net overall solar efficiencies in the range 80.8% to 83.9%. To summarise, the MPCM slurry based PV/T thermal and power system is superior to conventional air-sourced heat pump systems (ASHP) and solar assisted heat pump systems (ISAHP), and has the potential to help reduce fossil fuel consumption and carbon emission to the environment.

In this experimental study, the forced convection heat transfer of thermally developing Fe2O3/wat... more In this experimental study, the forced convection heat transfer of thermally developing Fe2O3/water nanoparticles inside a copper tube under magnetic field created by a number of permanent flat magnets is investigated. Experiments have been carried out under laminar flow regime and uniform heat flux boundary condition and the influence of magnetic field position and intensity. The objectives of this study were to investigate the effect of using Fe2O3/water nanofluid, flow Reynolds number, intensity and magnetic field position on the thermal behavior of the flow. Validation of the test apparatus was performed using distilled water and compared with the theoretical results, which eventually achieved good agreement. The results show that due to the influence of the magnetic field on the Fe2O3/water nanofluid, secondary flow and boundary layer deformation occur, the heat transfer changes and its variation is dependent on the flow profile and intensity and position of the magnetic field....

ARTICLE INFORMATION ABSTRACT Original Research Paper Received 03 July 2016 Accepted 18 September ... more ARTICLE INFORMATION ABSTRACT Original Research Paper Received 03 July 2016 Accepted 18 September 2016 Available Online 09 October 2016 Accurate measurement of unsteady pressure fluctuations along a surface requires experimental set up with high spacing resolution and high frequency domain. Therefore, in recent decades extensive studies have been conducted on remote microphone approach. In this method, instead of using flash mounted sensors, they were installed remotely and connected to the model surface through one or several continuously connected tubes. Surface pressure fluctuations travel within the tubing in the form of sound waves and they are measured when passing over the remote pressure sensor, mounted perpendicular to the tubing. In the present study, an analytical solution of sound waves propagation inside the rigid tubes is used for modelling of the remote microphone system and to investigate the effects of its parameters on dynamic response. In order to verify the accura...

Advanced Powder Technology

Journal of Thermal Analysis and Calorimetry

International Journal of Nano Dimension, Jan 12, 2015

In this research, some more applicable ferrofluids are produced and their mechanical specificatio... more In this research, some more applicable ferrofluids are produced and their mechanical specifications are measured, experimentally. Also, their treatments in the ventilated cavity geometry are assessed numerically. The magnetite nanoparticles are produced by a chemical combination of Fe 2+ and Fe 3+ with NH 3. In order to solve the nanoparticles in the new mediums, a proper coating is added to them. Then they are solved in kerosene, brake oil, hydraulic oil and motor oil with different particle fractures. A pressure-based procedure to solve Navier-stokes equations with finite volume formulation is developed to simulate a magnetic fluid in ventilated cavity geometry. One of the usages of this geometry is found in magnetic separation. The ventilated cavity geometry includes a square medium with one velocity inlet and one velocity outlet. In addition, a magnetic field due to a DC current carrying wire is employed on the geometry. The magnetic field intensities, its positions and ferrofluids' mediums are changed. Then, the flow characteristics for each case are obtained to find the optimum situation for magnetic separation. Finally, the optimum situations for magnetic separation and for local cooling are obtained and the best ferrofluid is suggested for each application.

In this research, some more applicable ferrofluids are produced and their mechanical specificatio... more In this research, some more applicable ferrofluids are produced and their mechanical specifications are measured, experimentally. Also, their treatments in the ventilated cavity geometry are assessed numerically. The magnetite nanoparticles are produced by a chemical combination of Fe2+ and Fe3+ with NH3. In order to solve the nanoparticles in the new mediums, a proper coating is added to them. Then they are solved in kerosene, brake oil, hydraulic oil and motor oil with different particle fractures. A pressure-based procedure to solve Navier-stokes equations with finite volume formulation is developed to simulate a magnetic fluid in ventilated cavity geometry. One of the usages of this geometry is found in magnetic separation. The ventilated cavity geometry includes a square medium with one velocity inlet and one velocity outlet. In addition, a magnetic field due to a DC current carrying wire is employed on the geometry. The magnetic field intensities, its positions and ferrofluids...

Since the electricity and the other modern energy sources had not been developed in the past, hum... more Since the electricity and the other modern energy sources had not been developed in the past, human being inevitably was trying to find ways to provide comfort of living. One of these cases is Baad-Gir which since a long time ago has been used and appreciated by the general public in hot and dry climate zones dwellers. Now, in addition to growing tendency of researchers to use renewable energy, they are more than willing to improve performance of traditional methods. In the present work, a method has been proposed and investigated to provide room air based on using underground channel. Since the subsurface soil temperature is much lower than the surface and due to the large volume of soil, it can be considered and used as a heat sink, without any costs and power consumption. In this work, two channels are considered, dry one which is modeled according to soil temperature and the other wet one, via using Ghanat or by adding water manually. Results are compared and it is concluded tha...

Climate change, global warming, and the recent worldwide economic crisis have emphasized the need... more Climate change, global warming, and the recent worldwide economic crisis have emphasized the need for low carbon emissions while also ensuring economic feasibility. In this paper, the status and wind power potential of the city of Shahrbabak in Kerman province in Iran was investigated. The technical and economical feasibility of wind turbine installation is presented. The potential of wind power generation was statistically analyzed. The mean wind speed data of three-hour interval long term period from 1997 to 2005 was adopted and analyzed in order to determine the potential of wind power generation. The numerical values of the dimensionless Weibull shape parameter (k) and Weibull scale parameter (c) were determined. Annual values of "k" ranged from 1.725 to 1.930 with a mean value of 1.504, while annual values of "c" were in the range of 4.848-6.095 with a mean value of 5.314 (m/s). With the average wind power density of 100 W/m 2 , it is found that the city is not an appropriate place for construction of large-scale wind power plants, but is suitable for employment of off-grid electrical and mechanical wind driven systems. An economic evaluation was done in order to show feasibility of installing small wind turbines. It was concluded that it costs 18 cents for 1 kW h which is 5 cents more than the market price. Each turbine of 10 kW can supply power for icebox, washer, water pump, TV, lighting, electrical fan, charger, and air conditioning units for small houses. In order to utilize wind energy in the region, it is recommended to install small size wind turbines for electricity supply of public and public buildings and private houses.

International Journal of Design & Nature and Ecodynamics