Opportunities for mesoporous silica aerogels in parabolic trough collectors

There has recently been a renewed interest in mesoporous silica as an insulation material for use in linear concentrated solar receivers, but there has not yet been an evaluation of their performance in next-generation receiver designs. Here, we model the performance of a linear annular tube receiver insulated by mesoporous silica (MS) aerogels across a range of temperatures (400-700ºC) and pressures (ambient to high vacuum). We first model heat loss reduction methods to improve the performance of MS-based linear solar collectors such as optimizing the density and thickness, incorporating plasmonic nanoparticles, and operating the solar receivers under vacuum. As a test-case, we use parabolic trough focusing technologies to evaluate the collector efficiency of the MS-based receiver designs. To do so, we use a previously established framework for the optical efficiency of parabolic trough collectors (PTCs). We compare the potential gains in collector efficiency of the heat loss reduction methods compared to the current state-of-the-art MS-based receiver design. Lastly, we evaluate the efficacy of a tandem receiver design that incorporates both MS and select air-stable selective absorbers (SA). Our findings show that the collector efficiency of MS-based receivers integrated with PTCs can be increased by 2-5% by simply optimizing the thickness and density of the MS. Additionally, SA-based receivers are expected to outperform MS-based receivers for temperatures 550°C and below, but MS-based receivers are significantly more efficient at 700°C. Lastly, tandem SA/MS-based receivers are unlikely to provide any improvement to the collection efficiency. Our results here can guide future developments of linear MS-based solar receivers.