In this study, attention is focused to examine experimentally how utilization of porous foams, as well as nanofluids, may improve thermal performance of a residential–type direct absorption solar collector (DASC). The experiments are undertaken for SiC ceramic as the porous foam and SiC–water suspension as the nanofluid. Three levels are chosen for the reduced temperature difference, the porous foam, and the volumetric flowrate while four levels are selected for the nanoparticle concentration. To determine the relative importance of each of the involved parameters on thermal efficiency of the DASC, an ANOVA is undertaken. The best thermal performance is achieved in a case having both the metal foam and the nanoparticles. The maximum rises in thermal efficiency due to the insertion of the porous foam and the inclusion of the nanoparticles are recorded to be 14% and 37%, respectively. However, it is found that the volumetric flowrate is the dominant parameter in this system in a way that the inclusion of the porous foam or the nanoparticles deteriorates its role. Comparison of the results of the two porous foams demonstrates that the foam having higher porosity and pore density leads to higher thermal efficiency.

中文翻译：

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用于改善直接吸收太阳能集热器热性能的多孔泡沫和纳米流体：一项实验研究

在这项研究中，注意力集中在实验上检查多孔泡沫以及纳米流体的利用如何改善住宅型直接吸收太阳能集热器 (DASC) 的热性能。实验以碳化硅陶瓷为多孔泡沫，碳化硅水悬浮液为纳米流体。为减小的温差、多孔泡沫和体积流量选择了三个级别，而为纳米颗粒浓度选择了四个级别。为了确定每个相关参数对 DASC 热效率的相对重要性，进行了方差分析。在同时具有金属泡沫和纳米颗粒的情况下实现最佳热性能。由于多孔泡沫的插入和纳米颗粒的包含，热效率的最大上升分别记录为 14% 和 37%。然而，发现体积流量是该系统中的主要参数，而多孔泡沫或纳米颗粒的包含会降低其作用。两种多孔泡沫的结果比较表明，具有较高孔隙率和孔密度的泡沫导致更高的热效率。