An approach for IC engine coolant energy recovery based on low-temperature organic Rankine cycle

Fu Jian-qin(付建勤), Liu Jing-ping(刘敬平), Xu Zheng-xin(徐政欣), Deng Bang-lin(邓帮林), Liu Qi(刘琦)

(Research Center for Advanced Powertrain Technology, Hunan University, Changsha 410082, China)

Abstract:To promote the fuel utilization efficiency of IC engine, an approach was proposed for IC engine coolant energy recovery based on low-temperature organic Rankine cycle (ORC). The ORC system uses IC engine coolant as heat source, and it is coupled to the IC engine cooling system. After various kinds of organic working media were compared, R124 was selected as the ORC working medium. According to IC engine operating conditions and coolant energy characteristics, the major parameters of ORC system were preliminary designed. Then, the effects of various parameters on cycle performance and recovery potential of coolant energy were analyzed via cycle process calculation. The results indicate that cycle efficiency is mainly influenced by the working pressure of ORC, while the maximum working pressure is limited by IC engine coolant temperature. At the same working pressure, cycle efficiency is hardly affected by both the mass flow rate and temperature of working medium. When the bottom cycle working pressure arrives at the maximum allowable value of 1.6 MPa, the fuel utilization efficiency of IC engine could be improved by 12.1%. All these demonstrate that this low-temperature ORC is a useful energy-saving technology for IC engine.

Key words:IC engine; waste heat recovery; organic Rankine cycle; cycle efficiency; coolant energy