Operation performance comparison of CCHP systems with cascade waste heat recovery systems by simulation and operation optimisation

The waste heat recovery system (WHRS) is a critical part of the combined cooling, heating, and power (CCHP) system and can evidently improve its primary energy utilisation rate. However, few researchers have investigated the operation performance of the WHRS with the entire CCHP system to reveal its effects on the CCHP system efficiency. Therefore, dynamic simulation models of an entire CCHP system with a novel cascade WHRS named 'electricity-cooling cogeneration system (ECCS)' and a dual-effect absorption refrigeration system (DARS) are established in this study. The operation performances of the CCHP system-ECCS and CCHP system-DARS are compared based on dynamic simulations, thereby focusing on the effects of different WHRSs. In addition, the dynamic simulation results are compared with the results of operation optimisation and static simulation to reveal the applicability of the different methods. The optimisation and dynamic simulation results of the CCHP system operation agree well when the off-design performance is considered. Furthermore, the dynamic simulation results enable a more detailed analysis, thereby showing that the CCHP system-ECCS requires 0.29% less primary energy. Besides, under slow variations in load, the simulation results of the static and dynamic models have no evident difference, and the maximal error is only approximately 0.5%. (C) 2020 Published by Elsevier Ltd.