Development of a powerful miniature power system with a meso-scale vortex combustor

With the use of a meso-scale vortex combustor and a couple of thermo-electric devices (TED), a powerful miniature power system has been developed. A vortex combustor with a 10-mm inner diameter was fabricated inside of a heat medium of 52 x 52 x 13-mm, on which a couple of thermo-electric devices were placed. Propane was used as fuel, and the system outputs are examined for three thermal input conditions of P-in = 400, 500 and 600 W. Results show that, the system output reached a steady state within 5-minutes after ignition. The maximum system output increased with the thermal input, and reached a maximum of 18.1 W (11.3 V x 1.6A) for Pin = 600 W, with a 3.01% conversion efficiency. The system output of 18.1 W is higher than any currently available other miniature combustion power system, and the conversion efficiency is also high compared to that of other power systems with high thermal input (P-in > 100 W). Analyses have been made on the heating efficiency and convective heat transfer of the small scale vortex combustor. As a result, it was confirmed that the heating efficiency of the vortex combustor is considerably high, that is, 85% of the thermal input was effectively used to heat the heat medium, and 70% of the input heat was supplied to the TED and used for power generation for all experimental conditions. The results of the heat transfer analysis showed that the heat transfer in the narrow channel was significantly enhanced by the vortex motion of the gas. This characteristic contributes to the high efficiency heating, and hence, the considerably high output power as well as the high system efficiency of the vortex combustion power system. (C) 2016 by The Combustion Institute. Published by Elsevier Inc.