Session: 08-01 Thermal Energy Conversion Techniques

Paper Number: 108512

108512 - Optical Cavities for Thermophotovoltaic Systems Powered by Multiple Heat Sources 

Thermophotovoltaic (TPV) systems use a photovoltaic cell with a low band-gap to convert radiant heat from an emitter heated to ultra-high temperatures (typically more than 1000 °C). TPV systems are a versatile technology with many applications including self-powered heating devices, industrial waste heat recovery, and uninterruptible power supplies. More recently TPV systems have attracted attention for their use in thermal energy storage systems, wherein a portion of the thermal energy stored at ultrahigh temperatures in materials such as graphite can be converted to electric power. TPV systems can also be used to convert heat generated from burning renewable fuels, such as biofuels, into electric power. Furthermore, TPV systems can convert concentrated solar power into electric power. The efficiency and power output of TPV systems increase rapidly as the temperature of the emitter increases. For this reason, it can be advantageous to increase the temperature of the emitter by powering a TPV system with multiple heat sources. For example, solar energy can be concentrated onto an emitter that is heated using biofuels to boost the output power. Recently, we have developed TPV systems comprised of robust components, including ellipsoidal optical cavities that exhibit enhanced performance. Herein we present novel optical cavity configurations used to enhance the performance of TPV systems that are simultaneously powered by solar energy and a fuel source. The optical cavities are designed to reflect a portion of the photons from the emitter such that they are returned to the emitter in order to elevate its temperature. The extent to which this ‘photon recycling’ occurs can be controlled during operation to optimize the emitter temperature and output power. Thus, high emitter temperatures can be maintained during partially cloudy weather or during periods of reduced solar irradiation by increasing the degree of photon recycling. Results from numerical analysis shows that the efficiency of TPV systems powered using solar energy or fuel sources individually can be increased by more than 100% by using these sources simultaneously in an optical cavity-based TPV system.   

Presenting Author: Paul O'Brien York University

Presenting Author Biography: Paul G. O’Brien is an Associate Professor in the Department of Mechanical Engineering, York University, Canada and has extensive experience working in leading research labs based in materials, mechanical, electrical and chemical engineering. His interdisciplinary research efforts focus on the application of expertise from these fields to develop solutions for the realization of a transition to clean energy. Dr. O’Brien has authored over forty papers in the areas of materials and energy. He is the founder of the Advanced Materials for Sustainable Energy Technologies Laboratory at York University, Canada, where he and his students continue to innovate and advance clean energy solutions.