Potential of applying the thermochemical recuperation in combined cooling, heating and power generation: Off-design operation performance

Abstract

Combined cooling, heating and power system (CCHP) as a typical distributed energy utilization technology, is usually installed close to the end-user to satisfy the diverse energy demands, which also has multiple advantages of energy-efficient and environment-friendly. While the simultaneously changing user energy loads brings about a huge challenge for the system energy conversion and regulation process, and then significantly affects the system operation flexibility. Therefore, the new method of thermochemical recuperation (TCR) is employed to enhance the system dynamic energy utilization performances, and also efficiently converts the high-temperature exhaust gas heat into hydrogen-enrich syngas for further application. In this work, by considering the practical system operation, the off-design TCR operation adjustment capacity for the system diverse energy outputs is important, which is extensively investigated. Based on the developed mathematic model, different-size (small, middle and large) gas turbine scenarios are considered, the results indicate that the TCR process effectively optimize the system energy conversion process, and the corresponding power efficiencies are improved by 10.53%–13.87%, 8.56%–14.46% and 14.23%–14.42%, respectively. In addition, with the merits of adaptively coordinating the multi-energy production, the off-design energy outputs boundary of the CCHP system can be extended and then readily match the fluctuant user loads. Specifically, as for the small scale GT-based system application in a hotel building case, the system annual recuperated fuel ratio reaches to 0.54 with the annual coordinated recuperation operation time ratio of 0.70, and then the system operation flexibility is thus enhanced with the annual fuel saving ratio of 6.03%, which also contributes to the CO2 emission reduction. With the favorable potential to optimize the CCHP system operation regulation, the thermochemical recuperation technology provides a feasible pathway to enhance the distributed energy system application feasibility.