Modelling and Optimal Design of Gas Engine CCHP System in Hospital

Abstract

The combined heating and power (CHP) system and the combined cooling, heating and power (CCHP) system have attracted great attention during the last decade. However, many CHP systems don’t perform well in the actual operation. This paper presents a complete hierarchical modeling tool of the gas engine CHP/CCHP system which is built on the software Dymola. Meanwhile, a gas-engine CHP hybrid energy system serving a hospital in Shanghai is studied as a case. To validate the accuracy of newly-built models, the operating data of the CHP part of the system in 2017 is compared with the simulation results, it is found that the minimum error is 2.1%, and the maximum error is 7.0%. Then, the original gas engine CHP hybrid energy system is reconstructed to a gas engine CCHP system. To analyze the feasibility of the optimal design, the conventional energy supply system which was used in the hospital before 2013, the original gas engine CHP hybrid energy system and the optimized gas engine CCHP system are modeled and simulated. From the simulation results, it is found that the primary energy ratio is increased from 72.55% to 133.37%, the payback period of investment is decreased from nearly 11.8 years to 3.9 years, and the CO2 emissions reduction rate is increased from 4.83% to 93.72%. Therefore, the optimization scheme is feasible.