Performance of a micro-thermophotovoltaic power system using an ammonia-hydrogen blend-fueled micro-emitter

The potential of ammonia (NH3)-hydrogen (H2) blends as a carbon-free, green fuel in a 1–10 W micro-thermophotovoltaic (micro-TPV) device is evaluated experimentally. When NH3–H2 blends are used directly (without any modification) in a heat-recirculating micro-TPV configuration that has an installation of gallium antimonide (GaSb) photovoltaic cells and was developed for hydrocarbon fuel, low temperature on the micro-emitter outer surface is observed, generating a secondary flame at the micro-emitter outlet. Thus, the micro-TPV device has been modified to eliminate the secondary flame by enhancing the residence time of fed NH3–H2–air mixtures and uniform burning: a cyclone adapter for a fuel-air mixture supply system and a helical adapter for the fuel-air mixture upstream of the micro-emitter. Under optimized design and operating conditions, the micro-TPV device produces 5.2 W with an overall efficiency of 2.1% and an emitter efficiency of 37%, indicating the maximum temperature of the micro-emitter outer surface up to 1408 K. Thus, the feasibility of using NH3–H2 blends in practical micro power-generation devices has been demonstrated, implying the potential of partial NH3 substitution to improve the safety of pure H2 use with no carbon generation.