RECENT ADVANCEMENTS in MICROCOMBUSTION-BASED POWER GENERATORS

The limitations posed by electrochemical batteries due to their lower power densities, bulky volumes, and environmental hazards from their disposal have promoted the development of small-scale combustion-based power generators as an alternative power source for various microelectromechanical systems applications. Microcombustors are considered to be a viable heat source for these power generators due to the high power density of hydrocarbon and hydrogen fuels and the recent innovations in micromachining and microfabrication techniques. Because of their high heat loss to heat generation ratio, flow and heat recirculation techniques are used to improve the flame stability limits of microcombustors. In the present study, two types of direct micropower generators are reviewed in detail. There is a consensus among researchers that favors thermoelectric generators (TEGs) and thermophotovoltaic systems over micro-gas turbines due to the presence of moving parts, lower power densities, and complex manufacturing techniques involved in the development of the latter. Progress in the field of TEGs has been analyzed by highlighting the challenges faced in terms of thermoelectric materials and efficient thermal management. A maximum power output of 30 W and maximum conversion efficiency of 5% have been reported by various researchers using TEG-based power generators.