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| 1 | Thermal Analysis of a Phase Change Material Based Heat Sink for Cooling Protruding Electronic Chips显示文摘This work aims to numerically study the melting natural convection in a rectangular enclosure heated by threediscreet protruding electronic chips. The heat sources generate heat at a constant and uniform volumetric rate. Apart of the power generated in the heat sources is dissipated to a phase change material (PCM, n-eicosane withmelting temperature, Tm=36℃). Numerical investigations were carried out in order to examine the effects of theplate thickness on the maximum temperature of electronic components, the percentage contribution of plate heatconduction on the total removed heat and temperature profiles in the plate. Correlations for the dimensionless securedworking time (time to reach the threshold temperature, Tcr=75℃) and the corresponding liquid fractionwere derived. | Mustapha FARAJI Hamid EL QARNIA EI Khadir LAKHAL | 2009 | Journal of Thermal Science2009，18，3： | 3 |
| 2 | Experimental Investigation of Heat Storage and Heat Transfer Rates during Melting of Nano-Enhanced Phase Change Materials (NePCM) in a Differentially-Heated Rectangular Cavity显示文摘In this work, an experimental study of melting heat transfer of nano-enhanced phase change materials(NePCM) in a differentially-heated rectangular cavity was performed. Two height-to-width aspect ratios of the cavity, i.e., 0.9 and 1.5, were investigated. The model Ne PCM samples were prepared by dispersing graphene nanoplatelets(GNP) into 1-tetradecanol, having a nominal melting point of 37℃, at loadings up to 3 wt.%. The viscosity was found to have a more than 10-fold increase at the highest loading of GNP. During the melting experiments, the wall superheat at the heating boundary was set to be 10℃ or 30℃. It was shown that with increasing the loading of GNP, both the heat storage and heat transfer rates during melting decelerate to some extent, at all geometrical and thermal configurations. This suggested that the use of NePCM in such cavity may not be able to enhance the heat storage rate due to the dramatic growth in viscosity, which deteriorates significantly natural convective heat transfer during melting to overweigh the enhanced heat conduction by only a decent increase in thermal conductivity. This also suggested that the numerically predicted melting accelerations and heat transfer enhancements, as a result of the increased thermal conductivity, in the literature are likely overestimated because the negative effects due to viscosity growth are underestimated. | LI Zirui HU Nan TU Jing FAN Liwu | 2020 | Journal of Thermal Science2020，29，2： | 0 |
| 3 | 基于正交试验法的二维方腔相变传热影响因素的数值分析显示文摘以单元内相变材料熔化完成时间为试验指标,换热温差、高宽比、倾角为影响因素,运用正交试验法设计二维方腔数值模拟试验,并通过极差分析与方差分析研究各因素及其交互作用对单元平均熔化传热速率的影响程度,且两种分析方法得到的结果一致。研究结果表明:在设计与优化方腔相变单元时(换热温差20~40℃,高宽比1~4,倾角0°~60°),应着重考虑换热温差与倾角两个关键参数以及高宽比与倾角的交互作用,适当考虑高宽比的影响,可不考虑换热温差与高宽比以及换热温差与倾角的交互作用。 | 龙伟月 袁艳平 曹晓玲 向波 孙亮亮 | 2017 | 太阳能学报2017，38，12： | 0 |
| 4 | Natural Convection in a Horizontal Cylinder with Partial Heating: Energy Efficiency Analysis显示文摘The current study reports a numerical analysis of free convection of air in an isothermal horizontal cylinder,cooled and heated at different wall locations.Three heater sizes are discussed in this study.The first heated zone is spread across one-quarter of the sidewall;the second is uniformly distributed over the half of the wall and the third active wall covers three-quarters of the cylinder.Five various locations are considered and examined for each active zone of the sidewall.The computation is carried out for Rayleigh number ranging from 102 to 106.Numerical results characterizing heat transfer and flow features are achieved using an iterative model developed in COMSOL Multiphysics.The effect of Rayleigh number on heat transfer and fluid flow characteristics within the cavity are investigated.Particular attention is paid to the influence of heater location and heater size on energy efficiency.It is found that the mean Nusselt number and dimensionless velocity increase when increasing the Rayleigh number.Moreover,the optimal level of energy efficiency is achieved if the heating zone is centered at the upper part of the cylinder,regardless of the heater size.It is also shown that the optimal configuration providing higher energy efficiency is obtained when three-quarters of the sidewall are locally heated,and more precisely,if the active zone is centered at the top of the cylinder. | MAZGAR Akram JARRAY Khouloud HAJJI Fadhila BEN NEJMA Faycal | 2020 | Journal of Thermal Science2020，29，6： | 0 |
| 5 | 不同厚度储能单元内相变传热强化及经济效益显示文摘以正十八烷为相变材料,在等热流加热条件下,对不同厚度大长宽比矩形储能单元内的相变材料融化传热过程进行试验.通过对融化相变过程中储能单元被加热面的温度检测,验证融化过程中存在相变材料固相部分的重力沉降效应,该效应强化了相变传热.试验结果表明,不同厚度的储能单元均在倾斜角为90°时融化相变传热的效果最佳;通过经济效益分析,得储能单元厚度为20mm,倾斜角为90°时,在提高相变传热的基础上经济效益最佳. | 张又升 赵敬德 卢一杭 | 2017 | 东华大学学报(自然科学版)2017，43，2： | 0 |
| 6 | 重力沉降效应对相变材料融化传热过程的影响显示文摘以正十八烷为相变材料,在不同加热功率的等热流边界条件下,对大长宽比矩形储能单元在不同倾斜角度下的相变材料融化过程进行了试验.通过对相变过程中储能单元壁面的温度监测,确定相变材料融化过程中固相重力沉降效应对融化过程的传热强化效果.试验结果表明,当加热功率为60 W、储能单元倾斜角为90°时,作为相变材料的正十八烷的传热效果为最佳. | 张又升 赵敬德 李雷雷 | 2017 | 东华大学学报(自然科学版)2017，43，1： | 0 |
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