摘要
多孔介质材料具有良好的传热和蓄热性能。设计了新型多孔介质辅助平板式太阳能集热器的二维数值仿真模型,对其内部热性能进行了数值模拟,研究多孔介质块的形状(矩形、梯形、三角形结构)、布置数量和渗透率(达西数Da=10^(-5)~10^(-2))等因素对平板式太阳能集热器热性能强化的影响;然后考虑到插入多孔介质伴随的压降和摩擦阻力损失,提出了评价集热器传热性能与阻力损失的性能评估标准。研究结果表明:在平板式太阳能集热器换热通道插入4种不同形状的多孔介质块,矩形多孔介质块背部附近区域更易产生涡区,集热器内传热性能最强,但通道内流动阻力系数大,从而导致阻力损失大。当多孔介质区域总长度一定时,随着多孔介质块布置数量的增加,涡区数量相应增加,集热器内传热性能加强,且通道内流动阻力损失呈现先增加后降低的规律。多孔介质块渗透率对集热器传热性能的影响显著,当Da=10^(-2)时,集热器传热性能最强。集热器内多孔介质块布置任意数量、高渗透率(Da=10^(-2))条件下,矩形多孔介质块的性能评估标准最佳;在多孔介质块布置数量(N=6)较多、低渗透率(Da=10^(-5)、Da=10^(-4))条件下,三角形多孔介质块的性能评估标准最佳。
Porous media have many good performances of heat transfer and thermal storage.In this paper,a 2D numerical simulation model of a novel porous media assisted flat-plate solar collector(FPSC)is designed,and its internal thermal performance is numerically simulated.The influence of the shape of porous media blocks(rectangular,trapezoidal,triangular),the inserting number and permeability(Da=10^(-5)~10^(-2)) on the enhanced thermal performance of FPSC is studied.Then,considering the pressure drop and friction resistance loss associated with the insertion of porous media,the performance evaluation criteria for evaluating the heat transfer performance and resistance loss of the collector are proposed.The results show that four different shapes of porous media blocks are inserted into the heat exchange channel of FPSC,and the regions near the back of the rectangular porous media block is more prone to generate vortex areas,the heat transfer performance in the collector is the strongest,but the flow friction coefficient in the channel is large,resulting in large resistance loss.When the total length of the porous media area is fixed,with the increase of the inserting number of porous media blocks,the number of vortex areas will increase correspondingly,the heat transfer performance in the collector will be enhanced,and the flow resistance loss in the channel will first increase and then decrease.The permeability of porous media block has a significant impact on the heat transfer performance of the collector.When Da=10-2,the heat transfer performance of the collector is the strongest.The performance evaluation criteria of rectangular porous media block are the best under the condition of arbitrary inserting number of porous media blocks in the collector and high permeability(Da=10^(-2)).Under the condition of high inserting number of porous media blocks(N=6)and low permeability(Da=10-5,Da=10-4),the performance evaluation criteria of triangular porous media blocks are the best.
作者
成祖德
林新伟
夏永放
王海涛
冯军胜
Cheng Zude;Lin Xinwei;Xia Yongfang;Wang Haitao;Feng Junsheng(School of Environmental and Energy Engineering,Anhui Jianzhu University,Hefei 230005,China)
出处
《太阳能》
2023年第2期40-51,共12页
Solar Energy
基金
安徽省重点研发计划专项项目(202004a07020049)
国家自然科学基金项目(51406123)。
关键词
多孔介质
平板式太阳能集热器
热性能
阻力损失
性能评估标准
porous media
flat-plate solar collectors
thermal performance
resistance loss
performance evaluation criteria
