Exhaust heat recovery performance analysis of a Bi-fuel engine utilizing a thermoelectric generation kit and fuel economy evaluation

Abstract

The internal combustion engine (ICE) exhaust gas temperature depends on fuel energy and combustion characteristics. The exhaust gas temperature of compressed natural gas fuel (CNG) is more than gasoline fuel and consequently, affect the thermoelectric generation (TEG) performance. This study evaluates how CNG and gasoline fuels affect exhaust temperatures, TEG power output and the brake specific fuel consumption (BSFC). In test setup, the engine exhaust channel is modified to support a thirty thermoelectric unit (TEM) in upper and lower of exhaust muffler; the TEM is clamped between exhaust mufflers and the cooling system to control the cold surface temperature of the TEM. The maximum power output and open circuit voltage of the TEG are described as functions of temperature difference. The electrical power output of the TEG is evaluated in terms of changing engine speed and load for both fuels. The result indicates that the CNG fuel has better temperature distribution of TEG Kit hot surface which can generate a maximum peak power output. The TEG kit can reach 178.3 W, while the gasoline fuel was 164.4 W. The average saving BSFC for a bi-fuel engine was (2.71%:3.20%) with TEG kit for both fuels.