The Experts below are selected from a list of 47244 Experts worldwide ranked by ideXlab platform
Farouk Fardoun - One of the best experts on this subject based on the ideXlab platform.
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Thermal behavior of a translucent superinsulated latent heat energy storage wall in summertime
Applied Energy, 2018Co-Authors: Farah Souayfane, Pascal Henry Biwole, Farouk FardounAbstract:This paper investigates the thermal performance of a translucent solar wall providing, concurrently, storage and restitution of heat, super thermal-acoustic insulation and daylighting to the interior environment. The wall is composed of glazing, silica aerogel used as a transparent insulation material (TIM) and glass bricks filled with fatty acid, an eutectic phase change material (PCM). To assess the TIM–PCM wall thermal behavior, experimentations were conducted in-situ in a full-sized test cell located in Sophia Antipolis, southern France. Experimental data shows that the tested wall is more Effective in winter and might cause overheating during the summer mainly due to solar gains and un-cycling behavior of PCM which remains in liquid state. To enhance the energy performance of the wall in summertime, a numerical model describing the heat transfer mechanisms occurring in the PCM layer in combination with the other transparent wall layers is developed. Then, the model of the wall is linked to TRNSYS software to assess the thermal performance of the whole building. The numerical model is validated experimentally and a good agreement is shown comparing the simulated values with the measured data for seven consecutive days in summer and winter. The importance of considering the natural Convection Effect in the liquid PCM is also demonstrated. Moreover, it was shown that shading devices can Effectively reduce overheating while natural night ventilation decreases the indoor temperature without affecting the PCM performance since the outdoor temperature is always higher than the phase change temperature. The use of a glass with selective solar reflection properties depending on the season instead of the ordinary glazing is shown also to be very Effective way to overcome the overheating problem. Finally, the TIM-PCM wall is tested under different climate conditions and passive solutions are given to ensure thermal comfort in summer season.
Robert A Taylor - One of the best experts on this subject based on the ideXlab platform.
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comparison of heat transfer between cylindrical and conical vertical shell and tube latent heat thermal energy storage systems
Applied Thermal Engineering, 2018Co-Authors: Saeid Seddegh, Saeed Mostafavi S Tehrani, Xiaolin Wang, Robert A TaylorAbstract:Abstract The shell-and-tube latent heat thermal energy storage (LHTES) system has been widely studied. In this paper, the Effect of geometric design on vertical shell and tube LHTES systems is investigated. Accordingly, cylindrical and conically shaped experimental tests are developed for this purpose. The thermal performance of the conical and cylindrical systems is compared experimentally and theoretically. The temporal variation of the experimental temperature is used to validate the mathematical model and demonstrate the Effects of natural Convection on heat transfer in the phase change material (PCM) during the charging and discharging processes of both systems. The melting/solidification time, liquid fraction, and stored/released energy are used to evaluate the performance of the two systems. The results show that the conical system can store thermal energy much faster than the cylindrical system at the same operating condition at a specific charging time before the system is fully charged. This is enabled since the conical design allows natural Convection to dominate in a large volume of PCM at top of the container. However, there is no significant difference during the discharging process. The results indicate that the natural Convection Effect can be advantageously utilized by optimization of the design of the shell-and-tube LHTES system.
Farah Souayfane - One of the best experts on this subject based on the ideXlab platform.
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Thermal behavior of a translucent superinsulated latent heat energy storage wall in summertime
Applied Energy, 2018Co-Authors: Farah Souayfane, Pascal Henry Biwole, Farouk FardounAbstract:This paper investigates the thermal performance of a translucent solar wall providing, concurrently, storage and restitution of heat, super thermal-acoustic insulation and daylighting to the interior environment. The wall is composed of glazing, silica aerogel used as a transparent insulation material (TIM) and glass bricks filled with fatty acid, an eutectic phase change material (PCM). To assess the TIM–PCM wall thermal behavior, experimentations were conducted in-situ in a full-sized test cell located in Sophia Antipolis, southern France. Experimental data shows that the tested wall is more Effective in winter and might cause overheating during the summer mainly due to solar gains and un-cycling behavior of PCM which remains in liquid state. To enhance the energy performance of the wall in summertime, a numerical model describing the heat transfer mechanisms occurring in the PCM layer in combination with the other transparent wall layers is developed. Then, the model of the wall is linked to TRNSYS software to assess the thermal performance of the whole building. The numerical model is validated experimentally and a good agreement is shown comparing the simulated values with the measured data for seven consecutive days in summer and winter. The importance of considering the natural Convection Effect in the liquid PCM is also demonstrated. Moreover, it was shown that shading devices can Effectively reduce overheating while natural night ventilation decreases the indoor temperature without affecting the PCM performance since the outdoor temperature is always higher than the phase change temperature. The use of a glass with selective solar reflection properties depending on the season instead of the ordinary glazing is shown also to be very Effective way to overcome the overheating problem. Finally, the TIM-PCM wall is tested under different climate conditions and passive solutions are given to ensure thermal comfort in summer season.
Kailong Hsiao - One of the best experts on this subject based on the ideXlab platform.
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stagnation electrical mhd nanofluid mixed Convection with slip boundary on a stretching sheet
Applied Thermal Engineering, 2016Co-Authors: Kailong HsiaoAbstract:Abstract In this study, the stagnation nano energy conversion problems have been completed for conjugate mixed Convection heat and mass transfer with electrical magneto hydrodynamic (EMHD) and heat source/sink Effects nanofluid flow field over a slip boundary stretching sheet surface. The physical phenomena varied which depended on different factors. All of the important nano energy conversion parameters S 0 , M, E, Gt, Gc, λ, Pr, Sc, Ncc, S and δ have represented the dominance of the magnetic energy Effect, electric Effect, mixed Convection Effect, heat generation/absorption energy Effect, heat transfer Effect, mass diffusion Effect, heat conduction–Convection Effect and slip boundary Effects, respectively. The similarity transformation and a modified Finite-Difference method are used to analyze the present nano energy conversion system's thermal energy conversion problem. The non-linear ordinary equations of the corresponding flow field momentum, temperature, concentration equations and plate sheet heat conduction equation are derived by employing the similarity transformation technology. The dimensionless non-linear ordinary equations are composed of momentum, temperature, concentration and plate sheet heat conduction equations which have been solved numerically by an improved finite difference technique.
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energy conversion conjugate conduction Convection and radiation over non linearly extrusion stretching sheet with physical multimedia Effects
Energy, 2013Co-Authors: Kailong HsiaoAbstract:Energy conversion for conjugate conduction, Convection and radiation analysis have been performed for free Convection heat transfer with radiation Effect of a steady laminar boundary-layer flow that pass a non-linearly flow field over extrusion stretching sheet by two kinds of boundary-layer conditions. The well-known Boussinesq approximation has been used to represent the buoyancy term adding to the governing equation. All of the important parameters m, Nr, Pr, G, Bi are represented the dominance of the non-linearly Effect, radiation Effect, free Convection Effect and conduction–Convection Effect which have been presented in governing equations, respectively. The similarity transformation and the finite-difference method have been used to analyze the present problem. The results were shown that the free Convection Effect will be produced a larger heat transfer Effect better than the forced Convection. On heat conduction processing, the Convection–conduction number Ncc or free Convection parameter G will be provided a good Effect with a larger value. The results are shown by graphics, so that it is a physical multimedia technique features study also.
Kamil Kaygusuz - One of the best experts on this subject based on the ideXlab platform.
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Thermal and heat transfer characteristics in a latent heat storage system using lauric acid
Energy Conversion and Management, 2002Co-Authors: Ahmet Sari, Kamil KaygusuzAbstract:The thermal and heat transfer characteristics of lauric acid during the melting and solidification processes were determined experimentally in a vertical double pipe energy storage system. In this study, three important subjects were addressed. The first one is temperature distributions and temporal temperature variations in the radial and axial distances in the phase change material (PCM) during phase change processes. The second one is the thermal characteristics of the lauric acid, which include total melting and total solidification times, the nature of heat transfer in melted and solidified PCM and the Effect of Reynolds and Stefan numbers as inlet heat transfer fluid (HTF) conditions on the phase transition parameters. The final one is to calculate the heat transfer coefficient and the heat flow rate and also discuss the role of Reynolds and Stefan numbers on the heat transfer parameters. The experimental results proved that the PCM melts and solidifies congruently, and the melting and solidification front moved from the outer wall of the HTF pipe (HTFP) to the inner wall of the PCM container in radial distances as the melting front moved from the top to the bottom of the PCM container in axial distances. However, it was difficult to establish the solidification proceeding at the axial distances in the PCM. Though natural Convection in the liquid phase played a dominant role during the melting process due to buoyancy Effects, the solidification process was controlled by conduction heat transfer, and it was slowed by the conduction thermal resistance through the solidified layer. The results also indicated that the average heat transfer coefficient and the heat flow rate were affected by varying the Reynolds and Stefan numbers more during the melting process than during the solidification process due to the natural Convection Effect during the melting process.