Dynamic exergy analysis of a novel LNG cold energy utilization system combined with cold, heat and power

Abstract

Plenty of cold energy is released through the regasification process of liquified natural gas (LNG). Thus, the LNG cold energy utilization has become a hot issue of research in both academic and engineering area. In this study, a novel LNG cold energy utilization system integrating a gas turbine, four Rankine cycles and a NG directly expander is proposed and analyzed by the dynamic exergy method. Moreover, LNG regasification pressure and air inlet temperature are selected for the parameter sensitive analysis. At last, a typical hotel located in South China is chosen as the study case. The results show that comparing with the traditional CCHP system, the novel system has higher Power/Cold ratio and Heat/Cold ratio which can reach to 5.55 and 3.65, respectively. Besides, the system exergy efficiency can reach to 48.97% at specific conditions. Furthermore, it has a variation section in where the system exergy efficiency decreases sharply due to the influence of the regasification pressure of LNG. Moreover, the proposed system has higher exergy efficiency when it is working at lower atmospheric temperature.