Potential of applying the thermochemical recuperation in combined cooling, heating and power generation: Flexible demand response characteristics

Abstract

• Thermochemical recuperation is employed to optimize the system energy conversion. • System multi-energy output boundary is widely extended with adaptive exhaust heat recuperation. • Flexible demand response characteristics can be realized under fluctuant terminal energy loads. • The thermodynamic performances within the system practical operation can be improved. Combined cooling, heating and power (CCHP) system as a promising distributed energy utilization technology, is usually installed close to the terminal users and satisfies diverse energy demands. Whereas, the simultaneously changing user loads, mainly affected by the user behaviors and fluctuant ambient conditions, evidently deteriorate the system practical operation flexibility. In this work, the thermochemical recuperation (TCR) method is integrated to optimize the system internal configuration and the energy conversion process. Meanwhile, in order to further investigate the practical TCR operation regulation characteristics and the load matching performances, the modified CCHP system are comprehensively evaluated by the building application cases with four categories of hotel, hospital, office and shopping center. The results indicate that the exhaust gas heat recuperation effectively regulates the system waste heat conversion with the adjustable operation regulation, and then widely extends the system multi-energy supply boundary to match the fluctuant user loads. Within the implemented case study of the TCR-based CCHP system, the variable terminal demands can be well satisfied, with the annual recuperation operation time ratio of 0.478–1.0 and 0.063–0.560 for the corresponding gas turbine (GT) and the internal combustion engine (ICE) scenarios, which evidently improves the system operation flexibility with efficient demand response. Moreover, during the system annual operation under the GT and ICE conditions, the proportion 9.6%-24.3% and 1.1%-15.3% of the high-temperature exhaust gas heat can be readily recovered and optimize the fuel chemical energy utilization, the system thermal efficiencies are thus increased by 2.8%-13.7% and 0.1%-1.8%, respectively. Through the system thermodynamic and off-design operation evaluation with favorable performances, the TCR method provides an alternative way to optimize the system operation flexibility and demand response characteristics.