SBIR Phase I: Macroscale Knudsen Pumped Solar Thermal Collector

This Small Business Innovation Research (SBIR) Phase I project will assess the feasibility of a novel flat plate solar thermal collector with significantly improved performance and economics. Current small scale collectors are limited by radiative losses to a maximum operational temperature of 120C at efficiencies of 45% to 55%. The proposed design will use a novel heat retention strategy for both insulation and IR loss reduction. The design will also be optimized to induce thermal transpiration pumping. This effect will minimize or eliminate parasitic losses caused by pumping heat transfer fluids. For the proposed collector, recent models indicate theoretical operating temperatures in excess of 250C, efficiencies>70%, and a>3X cost reduction are attainable. The project will develop a comprehensive 3D multi-physics model of the collector and perform basic experiments to support it. A solar heating and cooling system performance/economic model will also be developed along with a preliminary manufacturing cost analysis. The result will provide the basis for the fabrication of a scaled up prototype in a follow on Phase II effort. The broader impact/commercial potential of this project is to lay the groundwork for a high performance solar thermal collector suitable for urban deployment in distributed solar heating cooling systems. Because of their performance, solar collectors on the U.S. market are limited to the generation of hot water. Due to low energy prices in the U.S., the solar water heating systems these collectors support have achieved only limited market penetration. Systems based on the new collector design will be capable of providing hot water as well as higher value energy resources such as space cooling and heating. The additional revenue streams will make them economically viable in a low-cost energy landscape. Conventional water heating via gas and electricity costs the US economy in excess of $27B per year and produces more than 180 megatons/year in CO2 emissions. Commercial and residential HVAC consumes 15% of the total energy used in the U.S., representing $150B/year in expenditures and over 80 megatons/year in CO2 emissions. Addressing these combined markets with solar solutions would realize hundreds of megatons in CO2 emissions reductions and save hundreds billions of dollars in energy expenditures in the U.S. alone.