Performance Analysis of an Organic Rankine Cycle with Different Working Fluids for Heat Recovery from an Internal Combustion Engine

Internal Combustion Engine (ICE)waste heat resources mainly include jacket cooling water heat and exhaust gas heat. However, jacket cooling water heat is usually ignored due to its low temperature in the bottoming cycle which uses Organic Rankine Cycle (ORC)to recover waste heat from an ICE. This paper establishes an optimization model of an ICE-ORC bottoming cycle to maximize the ORC net power output for different ICE rated power outputs with different working fluids. Moreover, three different ICE-ORC bottoming cycles are considered: a simple cycle with the use of only exhaust gas as the ORC thermal source, a cycle with the use of exhaust gas as the ORC thermal source and jacket cooling water preheating working fluid, and a cycle with a specific jacket cooling water circuit which includes a splitter and an exhaust gas heat exchanger. The results demonstrate that whether it is necessary to recover jacket cooling water waste heat depends on the property parameters of working fluid, each ICE-ORC bottoming cycle has a suitable working fluid to obtain maximum ORC power output respective, and the maximum ICE-ORC bottoming cycle efficiency could be increased by 16% using pentane as working fluid compared with single ICE generator set.