Experimental investigation of an improved exhaust recovery system for liquid petroleum gas fueled spark ignition engine

Abstract

In this study, we have investigated the recovery of energy lost as waste heat from exhaust gas and engine coolant, using an improved thermoelectric generator in a liquid petroleum gas fueled spark ignition engine. For this purpose, we have designed and manufactured a 5-layer heat exchanger from aluminum sheet. Electrical energy generated by the thermoelectric generator was then used to produce hydrogen in a proton exchange membrane water electrolyzer. The experiment was conducted at a stoichiometric mixture ratio, 1/2 throttle position and six different engine speeds at 1800-4000 rpm. The results of this study show that the configuration of 5-layer counterflow produce a higher thermoelectric generator output power than 5-layer parallel flow and 3-layer counterflow. The thermoelectric generator produced a maximum power of 63.18 W when used in a 5-layer counter flow configuration. This resulted in an improved engine performance, reduced exhaust emission as well as an increased engine speed when liquid petroleum gas fueled spark ignition engine is enriched with hydrogen produced by the proton exchange membrane electrolyser supported by thermoelectric generator. Also, the need to use an extra evaporator for the liquid petroleum gas fueled spark ignition engine is eliminated as liquid petroleum gas heat exchangers are added to the fuel line. It can be concluded that an improved exhaust recovery system for automobiles can be developed by incorporating a proton exchange membrane electrolyser, however at the expense of increasing costs.