Organic Rankine cycle configuration design method based on the performance of all operating conditions

For waste heat recovery organic Rankine cycle (ORC) systems with multiple waste heat sources, such as engine, solar and geothermal, the design process often ignores its variable operating condition requirements. Therefore, this study proposes an ORC configuration design method based on the performance of all operating conditions. This method takes the all condition energy matching degree between the ORC system and the waste heat source as an evaluation index during the design of the organic Rankine cycle system. The optimal ORC system configuration for operation under all operating conditions is obtained through comparative analysis of different heat transfer structures. This method was subsequently applied to design an ORC system for a diesel engine that can recover exhaust gas, charge air, and coolant. The results show that the dual pressure ORC system is expected to exhibit the best overall operation performance for multiple waste heat sources. An analysis of various heat transfer structures revealed that the engine coolant is the most specific waste heat source. It is difficult to achieve high-energy matching at all operating conditions when it is recovered simultaneously with exhaust or charge air.