The investigation of the Recuperative Organic Rankine Cycle models for the waste heat recovery on vehicles

Abstract

Organic Rankine Cycle (ORC) has been valued for its promising application on the Waste Heat Recovery (WHR) from vehicles. And Recuperative ORC (RORC) is considered suitable for the on-board application because of its high efficiency. However, the previous investigations of RORC, which based on GT-suite, mainly focused on the steady state and didn’t consider the combined model with engine. In this paper, a Basic ORC (BORC) model and 3 RORC models with different recuperative rate are combined with engine model and compared. The steady state result shows that with the recuperative rate rising, the cooling heat decreases while the net output power increases, which are beneficial to the on-board application. However, the longer response time and more charged refrigerant mass are disadvantages. Also, compared with BORC, the backpressure and performance of the engine are basically not affected when recuperator is added. The transient responses show that with the recuperative rate rising, the overshoot of the temperature and output power of RORC become more serious at the start-up phase, which may cause decomposition to the refrigerant and damage to the expander. At last, the responses of combined models under varying engine condition are studied. The results show that exhaust mass flowrate is mainly responsible for the engine backpressure variation. And RORC with higher recuperative rate has more advantages under heavy-duty engine condition.