Effect of the heat exchanger in the waste heat recovery system on a gasoline engine performance

Abstract

In this paper, the effects of increasing the back pressure on the engine performance by using heat exchangers mounted in the exhaust line to recover waste heat from the engine exhaust are described. An experimental study was conducted with two different types of heat exchanger, namely shell-and-tube-type heat exchangers and fin-and tube-type heat exchangers. The heat exchanger increased the resistance of the engine exhaust through the exhaust line, and the engine back pressure increased to 16kPa, which led to an increase in the brake specific fuel consumption by up to 3% depending on the operating conditions. The back pressure adversely affected the performance of the automotive engine combined with the Rankine cycle and thus caused the overall thermal efficiency of the system to deteriorate. Consequently, if the back-pressure effect was taken into account, the contribution of recovering heat from the engine exhaust to the improvement in the system efficiency was lower than expected.