Harnessing Heat Beyond 200 °C from Unconcentrated Sunlight with Nonevacuated Transparent Aerogels

Abstract

Heat at intermediate temperatures (120−220 °C) is in significant demand in both industrial and domestic sectors for applications such as water and space heating, steam generation, sterilization, and other industrial processes. Harnessing heat from solar energy at these temperatures, however, requires costly optical and mechanical components to concentrate the dilute solar flux and suppress heat losses. Thus, achieving high temperatures under unconcentrated sunlight remains a technological challenge as well as an opportunity for utilizing solar thermal energy. In this work, we demonstrate a solar receiver capable of reaching over 265 °C under ambient conditions without optical concentration. The high temperatures are achieved by leveraging an artificial greenhouse effect within an optimized monolithic silica aerogel to reduce heat losses while maintaining high solar transparency. This study demonstrates a viable path to promote cost-effective solar thermal energy at intermediate temperatures.

Ultrahigh-efficiency desalination via a thermally-localized multistage solar still

“…The silica aerogel suppresses heat losses from the solar absorber through conduction, convection, and radiation, due to its ultralow thermal conductivity and high infrared opacity. [34][35][36] Thermal energy is transferred from the absorber to the capillary wick attached on the backside, where brine is driven up by capillarity and evaporates due to the elevated temperature. Vapor travels across the air gap between the evaporator and condenser, releasing thermal energy through condensation.…”

Full-Spectrum Solar Energy Utilization and Enhanced Solar Energy Harvesting via Photon Anti-Reflection and Scattering Performance Using Nanophotonic Structure

“…[48,49] Many studies had been reported that convection, conduction, and radiation losses limited the temperature of the thermal absorber at high temperature. [50,51,52] The TE was enclosed in an insulating layer to inhibit conduction and convection heat losses. The transparent silica aerogel had high transmittance in solar spectrum, low emissivity in mid infrared and low thermal conductivity.…”

Dual-Stage Atmospheric Water Harvesting Device for Scalable Solar-Driven Water Production

“…This temperature value or even higher temperatures are achievable by engineering the solar absorber using spectrally selective surfaces or optically transparent aerogels. 37,38 We used our modeling to guide the choice of adsorbent-layer thickness (L 1 = L 2 = 6.4 mm), air-gap thickness (L v1 = L v2 = 20 mm), and packing porosity (ε = 0.7) for our experiments. Using AQSOA Z01, the dual-stage device has the potential to achieve greater performance provided that T H is at least $90 C. Using these design guidelines, we fabricated the prototype in Figure 3A with details of the composite adsorbent layer shown in Figure 3B.…”