One of the likely methods for enhancing heat transfer in a latent thermal energy storage system is the conception of a thermal unit.In this study,the orientation of oval tubes(horizontal,vertical,and oblique)in phase ...One of the likely methods for enhancing heat transfer in a latent thermal energy storage system is the conception of a thermal unit.In this study,the orientation of oval tubes(horizontal,vertical,and oblique)in phase change material(PCM,C_(19)-C_(20))-based shell-tube heat exchanger was analyzed with respect to the metal foam(MF)type(graphite,copper,and nickel)in comparison to the case of pure PCM.For this purpose,a two-dimensional mathematical model was developed to investigate the thermal efficiency of the PCM-metal foam based composite energy storage unit.It was concluded that the orientation of the oval tubes(oblique,horizontal,and vertical)has a negligible impact on the performance of the thermal unit during the melting/solidification processes.Based on the liquid/solid fraction,total enthalpy and the average temperature in the annular space,the performance of a heat exchanger during fusion/solidification periods is in the order:copper-MF>graphite-MF>nickel-MF>pure PCM.Whatever the adopted MF or the geometry of tubes,the melting process is expedited compared to the solidification mechanism.展开更多
An advanced ANSYS FLUENT-based model was developed for hydrogen recovery from a multi-tubular fixed-bed metal hydride(MH)reactor of large-scale design.The model was firstly validated by comparing its results to specif...An advanced ANSYS FLUENT-based model was developed for hydrogen recovery from a multi-tubular fixed-bed metal hydride(MH)reactor of large-scale design.The model was firstly validated by comparing its results to specific experimental data.Mass and heat transfer processes inside the fixed bed were investigated for various pressures and thermochemical characteristics of the MH(thermal conductivity,porosity and reaction parameters).The findings were reported as average,local and spatial changes in the metal’s bed temperature and hydrogen content.During the initial stage of the endothermic desorption(t<100 s),the bed temperature dropped dramat-ically in all cases.During this time,there was a massive emission of hydrogen.The bed temperature was then raised due to the reactor’s external convective heating,while the hydrogen release continued until the MH was completely dehydrided.The dehydrogenation rate of the MH was enhanced when the discharge pressure was raised.Furthermore,some other characteristics of the MH,i.e.,porosity,thermal conductivity,desorption rate constant and activation energy,significantly impacted the resulting mass and heat fluxes inside the bed material.展开更多
基金supported by the Ministry of Higher Education and Scientific Research of Algeria(Project No.:A16N01UN250320220002)the General Directorate of Scientific Research and Technological Development(GD-SRTD).
文摘One of the likely methods for enhancing heat transfer in a latent thermal energy storage system is the conception of a thermal unit.In this study,the orientation of oval tubes(horizontal,vertical,and oblique)in phase change material(PCM,C_(19)-C_(20))-based shell-tube heat exchanger was analyzed with respect to the metal foam(MF)type(graphite,copper,and nickel)in comparison to the case of pure PCM.For this purpose,a two-dimensional mathematical model was developed to investigate the thermal efficiency of the PCM-metal foam based composite energy storage unit.It was concluded that the orientation of the oval tubes(oblique,horizontal,and vertical)has a negligible impact on the performance of the thermal unit during the melting/solidification processes.Based on the liquid/solid fraction,total enthalpy and the average temperature in the annular space,the performance of a heat exchanger during fusion/solidification periods is in the order:copper-MF>graphite-MF>nickel-MF>pure PCM.Whatever the adopted MF or the geometry of tubes,the melting process is expedited compared to the solidification mechanism.
基金supported by The Ministry of Higher Education and Scientific Research of Algeria(Project No.:A16N01UN250320220002)the General Directorate of Scientific Research and Technological Development(GD-SRTD)of Algeria.
文摘An advanced ANSYS FLUENT-based model was developed for hydrogen recovery from a multi-tubular fixed-bed metal hydride(MH)reactor of large-scale design.The model was firstly validated by comparing its results to specific experimental data.Mass and heat transfer processes inside the fixed bed were investigated for various pressures and thermochemical characteristics of the MH(thermal conductivity,porosity and reaction parameters).The findings were reported as average,local and spatial changes in the metal’s bed temperature and hydrogen content.During the initial stage of the endothermic desorption(t<100 s),the bed temperature dropped dramat-ically in all cases.During this time,there was a massive emission of hydrogen.The bed temperature was then raised due to the reactor’s external convective heating,while the hydrogen release continued until the MH was completely dehydrided.The dehydrogenation rate of the MH was enhanced when the discharge pressure was raised.Furthermore,some other characteristics of the MH,i.e.,porosity,thermal conductivity,desorption rate constant and activation energy,significantly impacted the resulting mass and heat fluxes inside the bed material.
