Porous foams and nanofluids for thermal performance improvement of a direct absorption solar collector: An experimental study

Abstract

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.

Numerical Study on the Enhanced Thermal Performance of the Porous Media-Assisted Flat-Plate Solar Collector

“…As a passive way of enhancing heat transfer, porous media materials can be availably utilized, which has attracted immense attention for solar thermal applications in the past several decades [7][8][9][10]. Due to the presence of voids and energy storage, the porous media matrix plays a vital role in the efficiency improvement of thermal systems.…”

Direct absorption nanofluid-based solar collectors for low and medium temperatures. A review

“…Studies summarized in Table 4 demonstrate the capability of NDASC to outperform surface planar collectors, with efficiencies enhanced by 10-15 % using low particle volume fraction. Novel NDASC using porous materials [147] or in between absorbing plates [148] can also be found in Table 4.…”

Recent Developments in Optical and Thermal Performance of Direct Absorption Solar Collectors

“…The literature indicates that design modification is the most important parameter for nanofluid-based DASCs. Hooshmand et al [81] developed the porous-foam-filled DASC system. The 12 mm air gap was created between the double-pane collector glazing, and polyurethane foam was filled to reduce the heat losses.…”