Analytical method to evaluate energy saving potential of thermal energy storage in cogeneration system based on load characteristics

摘要

Integrating thermal energy storage (TES) with building cogeneration system is an effective way to improve part load efficiency and save primary energy consumption. In this paper, a novel analytical method is put forward to evaluate the energy saving potential of cogeneration system with TES equipment under following thermal load operation strategy. Moreover, the load fluctuation factor is defined, based on the maximal and average load amount, and its relationship with primary energy consumption and system exergy losses are established. The results show that the primary energy consumption is mainly influenced by three factors: (1) no-load fuel consumption ratio and rated efficiency of gas turbine; (2) heating load fluctuation factor; (3) ratio of heat to electricity load. Furthermore, with increasing gas turbine efficiency and heating load fluctuation factor, the primary energy saving ratio grows whereas system exergy loss declines. The illustrative example in Beijing indicates that the primary energy consumption decreases by 16% and 23% for the hotel and office building respectively in one typical winter day. This work can provide guidance for practical design cogeneration system with TES equipment.