Selection maps of dual-pressure organic Rankine cycle configurations for engine waste heat recovery applications

Abstract

Dual-pressure organic Rankine cycles are widely used for engine waste heat recovery. Moreover, several dual-pressure organic Rankine cycle configurations exist. The configuration design and parameter optimisation of an optimal dual-pressure organic Rankine cycle system under different engine waste heat source conditions is difficult. Thus, an efficient and accurate selection method is required. To select system parameters for different waste heat sources quickly and accurately, this study proposes a method for constructing system selection maps. To use this method and verify its correctness, we applied it to a practical example of a dual-pressure organic Rankine cycle system selection process. The selection maps demonstrate that the best dual-pressure organic Rankine cycle system can increase the net output power and thermal efficiency by 8.34 %–28.52 % and 8.43 %–32.38 %, respectively, compared to the dual-pressure organic Rankine cycle system with the lowest net output power and thermal efficiency. After obtaining selection maps, the key parameters affecting the distribution of each selection map were analysed, as well as the map itself. The selection maps considered in this study provide a reference for appropriately selecting dual-pressure organic Rankine cycle systems for engine waste heat recovery. This research method can be extended to other areas (geothermal and solar) for waste heat recovery and other cycle configurations for optimum selection and design. In engineering applications, the selection map allows for quick and accurate determination of the best matching system for the target waste heat source, which reduces the capital and time costs of technical advice.