Analysis of rankine cycle of R134a and R245fa gases with AVL cruise™ M for waste heat recovery in internal combustion

While in internal combustion engines only a fraction of the spent fuel energy converts into useful work, a significant amount of energy loss occurs, especially through cooling water and exhaust gases. In systems in which both mobile and stationary internal combustion are used, this waste thermal energy can be converted into useful work using a Rankine cycle heat engine, and there happens significant advantages. While the energy discharged through cooling water has a low temperature source, the potential for energy recovery through exhaust gases is higher due to the high temperature. Simultaneous energy recovery from both sources requires the use of different working fluids because the working fluids are directly affected by the source and well temperatures. In this study, R134a was used for energy recovery from cooling water and R245fa for energy recovery from exhaust gases and the effects of source temperature and working fluid flow rate on the cycle performance were investigated with the Rankine cycle model created in AVL CRUISE™ M programme. For the exhaust gas recovery application, analyses were performed at three different source temperatures 450, 500 and 550°C and working fluid flow rates 12, 14 and 16 l/min for a total of nine cases. Similarly, for the cooling water recovery application, nine different cases were created by keeping the source temperatures and working fluid flow rates at 80, 90 and 100°C and 2, 2.5 and 3 l/min, respectively and the results obtained were compared. The results of the study showed that the level of the flow rate of the working fluid according to the source temperature in waste heat energy recovery systems significantly affects the system performance.