Study of Combined Rice Husk Gasifier Thermoelectric Generator

Abstract

The use of a rice husk gasifier as a cook stove is limited to the domestic sector of developing countries primarily because it needs electrical energy to drive a blower for the gasification process. To solve this problem, we investigated the feasibility of attaching commercial thermoelectric (TE) modules made of bismuth–telluride materials to the gasifier's side wall, thereby creating a TE generator system that utilizes a proportion of the gasifier's waste heat. A rice husk gasifier TE generator (TE-RSG) having an internal diameter of 16cm was fabricated and tested. The TE generator system consisted of two commercial TE modules, a metal sheet wall which acted as one side of the gasifier's structure and served as the hot side of the TE modules and a rectangular fin heat sink at the cold side of the TE modules. A blower was used to suck the ambient air to cool the heat sink and blow the air from the heat sink to the reactor of the gasifier. Gasification was conducted in a temperature range of 500-700°C and gasification agent, air feeding rate of 18.6 m3/h. The results revealed that the electrical power output and the conversion efficiency depend on the temperature difference between the cold and hot sides of the TE modules. At the temperature difference of approximately 60°C, the unit achieved a power output of 3.9W and a conversion efficiency of 2.01%. Through a comparison of results between the theoretic model and the experimental system, the reasonability of this system model has been verified.