Achieving reasonable waste heat utilization in all truck operating conditions via a dual-pressure organic rankine cycle and its operating strategy

The engine of truck contains multiple waste heat sources. Waste heat recovery (WHR) in truck is a necessary approach to achieve energy saving and cleaner production. These heat sources vary transiently and have thermal management requirements. Therefore, effective waste heat utilization should fulfill both waste heat recovery and thermal management requirements. The dual-pressure organic Rankine cycle (DPORC) is suitable for complex and fluctuating heat sources. Furthermore, a suitable operation strategy is essential for the reasonable waste heat utilization under all engine working conditions and complex road conditions. Therefore, this study designs a DPORC-WHR system and its operation strategy. The essence of this operating strategy is that the evaporation pressure of system can be regulated at different engine loads, thus regulating the heat exchange of each waste heat source. The goal of this operating strategy is to control the waste heat utilization of exhaust gas, coolant and charge air to near 100% at all operating conditions. The dynamic model is established to validate the effectiveness of the proposed DPORC-WHR system and its operation strategy. The results show that the utilization rate of coolant, charge air and exhaust gas is greater than 87.47%, 88.34% and 95.45% respectively for all engine operating conditions. Under the road conditions tested, the DPORC-WHR system can improve engine BTE by 5.98%. The temperature of the coolant and charge air after heat exchange, superheat degree and pressure can be maintained within the target range. This study provides a basis for the operation and control of ORC-WHR system after coupling with the vehicle in the future.