An experimental investigation was conducted to measure the temperature variation across the flow channel and to determine the performance of a natural convection solar air heater at various tilt angles from 15, 30 and...An experimental investigation was conducted to measure the temperature variation across the flow channel and to determine the performance of a natural convection solar air heater at various tilt angles from 15, 30 and 45°. The results of the temperature profile across the air gap showed that heat transfer from the absorber plate to the air stream was mainly by convection. At a particular section, mean air temperature could be calculated from the arithmetic mean of the temperature profile across the air gap to within ± 2 ℃. The axial air temperature distribution was non linear and did not increase much beyond 1 m of collector length. It tended to decrease towards the end of the collector. Overall glass, absorber plate and mean air temperatures over the entire length of the solar air heater could be determined by averaging the mean axial temperatures to within ± 2 ℃. The heater performed better as inclination increased.展开更多
Current developments in magnetohydrodynamic(MHD)convection and nanofluid engineering technology have have greatly enhanced heat transfer performance in process systems,particularly through the use of carbon nanotube(C...Current developments in magnetohydrodynamic(MHD)convection and nanofluid engineering technology have have greatly enhanced heat transfer performance in process systems,particularly through the use of carbon nanotube(CNT)–based fluids that offer exceptional thermal conductivity.Despite extensive research on MHD natural convection in enclosures,the combined effects of complex obstacle geometries,magnetic fields,and CNT nanofluids in three-dimensional configurations remain insufficiently explored.This research investigates MHD natural convection of carbon nanotube(CNT)-water nanofluid within a three-dimensional cavity.The study considers an inclined cross-shaped hot obstacle,a configuration not extensively explored in previous works.The work aims to elucidate the combined effects of CNT nanofluid concentration,magnetic field strength,and obstacle inclination on fluid flow patterns and heat transfer characteristics.Numerical simulations are performed using the finite element method(FEM)based on the Galerkin Weighted Residual approach.The analysis systematically considers variations in Rayleigh number(Ra),Hartmann number(Ha),nanoparticle volume fraction(Φ),and obstacle inclination angle(θ).Results show that increasing Ra from 103 to 106 enhances convective heat transfer by up to 228%,while raising the CNT volume fraction to 4.5%improves heat transfer by about 64%.In contrast,strengthening the magnetic field from Ha=0 to Ha=100 suppresses fluid motion and reduces heat transfer by nearly 67%,whereas varying the obstacle inclination from 0○to 45○leads to a 4.6%decrease in efficiency.The addition of nanoparticles slightly increases viscosity,reducing flow intensity by 8.3%when Ha=0.Furthermore,a novel multiparametric correlation is proposed,accurately predicting the average Nusselt number as a function of Ra,Ha,ϕ,andθ,with an R2 of 0.98.These findings provide new insights into the role of geometry,magnetic effects,and nanofluids in heat transfer enhancement,offering practical guidance for the design and optimization of advanced thermal systems.展开更多
Peristaltic transport of a Newtonian incompressible fluid in the presence of applied mag netic field in an inclined channel with slip is investigated. A perturbation method of solu tion is obtained in terms of wall sl...Peristaltic transport of a Newtonian incompressible fluid in the presence of applied mag netic field in an inclined channel with slip is investigated. A perturbation method of solu tion is obtained in terms of wall slope parameter and analytical expressions are derived for average velocity and stream function using Saffman slip condition. The effects of var ious relevant parameters on average velocity and stream line pattern have been studied. It is found that average velocity increases with slip and decreases with permeability and magnetic parameter.展开更多
文摘An experimental investigation was conducted to measure the temperature variation across the flow channel and to determine the performance of a natural convection solar air heater at various tilt angles from 15, 30 and 45°. The results of the temperature profile across the air gap showed that heat transfer from the absorber plate to the air stream was mainly by convection. At a particular section, mean air temperature could be calculated from the arithmetic mean of the temperature profile across the air gap to within ± 2 ℃. The axial air temperature distribution was non linear and did not increase much beyond 1 m of collector length. It tended to decrease towards the end of the collector. Overall glass, absorber plate and mean air temperatures over the entire length of the solar air heater could be determined by averaging the mean axial temperatures to within ± 2 ℃. The heater performed better as inclination increased.
基金Deputyship for Research&Innovation,Ministry of Education in Saudi Arabia for funding this research work through the project number RI-44-0451.
文摘Current developments in magnetohydrodynamic(MHD)convection and nanofluid engineering technology have have greatly enhanced heat transfer performance in process systems,particularly through the use of carbon nanotube(CNT)–based fluids that offer exceptional thermal conductivity.Despite extensive research on MHD natural convection in enclosures,the combined effects of complex obstacle geometries,magnetic fields,and CNT nanofluids in three-dimensional configurations remain insufficiently explored.This research investigates MHD natural convection of carbon nanotube(CNT)-water nanofluid within a three-dimensional cavity.The study considers an inclined cross-shaped hot obstacle,a configuration not extensively explored in previous works.The work aims to elucidate the combined effects of CNT nanofluid concentration,magnetic field strength,and obstacle inclination on fluid flow patterns and heat transfer characteristics.Numerical simulations are performed using the finite element method(FEM)based on the Galerkin Weighted Residual approach.The analysis systematically considers variations in Rayleigh number(Ra),Hartmann number(Ha),nanoparticle volume fraction(Φ),and obstacle inclination angle(θ).Results show that increasing Ra from 103 to 106 enhances convective heat transfer by up to 228%,while raising the CNT volume fraction to 4.5%improves heat transfer by about 64%.In contrast,strengthening the magnetic field from Ha=0 to Ha=100 suppresses fluid motion and reduces heat transfer by nearly 67%,whereas varying the obstacle inclination from 0○to 45○leads to a 4.6%decrease in efficiency.The addition of nanoparticles slightly increases viscosity,reducing flow intensity by 8.3%when Ha=0.Furthermore,a novel multiparametric correlation is proposed,accurately predicting the average Nusselt number as a function of Ra,Ha,ϕ,andθ,with an R2 of 0.98.These findings provide new insights into the role of geometry,magnetic effects,and nanofluids in heat transfer enhancement,offering practical guidance for the design and optimization of advanced thermal systems.
文摘Peristaltic transport of a Newtonian incompressible fluid in the presence of applied mag netic field in an inclined channel with slip is investigated. A perturbation method of solu tion is obtained in terms of wall slope parameter and analytical expressions are derived for average velocity and stream function using Saffman slip condition. The effects of var ious relevant parameters on average velocity and stream line pattern have been studied. It is found that average velocity increases with slip and decreases with permeability and magnetic parameter.
