Dynamic operation characteristics of a combined cooling and power system

Regasification rate fluctuations of liquefied natural gas (LNG) cause a mismatch between the energy output of LNG and downstream user demand. To address this, the thermal energy storage via packed bed is coupled into the combined cooling and power system using LNG cold energy. Following this, the optimization design of this system is carried out by using a genetic algorithm, and an unsteady-state model of LNG regasification accompanied with cooling and power generation is developed to study the dynamic operation characteristics under fluctuating LNG demand. The results indicate that the introduction of thermal energy storage via packed bed effectively mitigates the thermodynamic performance fluctuations caused by the varied regasification rate. Under a typical LNG regasification rate curve, the power output of system with no packed bed fluctuates with varied regasification rate, with a peak-to-valley ratio reaching 33. In contrast, the power output of the system with a packed bed remains steady at the design value (0.0245 kWh/kgLNG) during the day period of fluctuating LNG demand, which proves the superiority of the packed-bed thermal energy storage for the LNG cold energy utilization. This study provides a theoretical framework to support the application of the packed bed-LNG cold energy utilization system.