Assessment of off-design performance of a combined cooling, heating and power system using exergoeconomic analysis

This paper presents the exergy and exergoeconomic analyses of a typical combined cooling, heating and power (CCHP) system under off-design conditions. The exergoeconomic-related parameters and unit exergoeconomic cost of the flows are discussed using the exergy cost allocation method based on energy level (ECAEL). The absorption chiller is found to have an improved potential because of the highest relative cost difference and its continual increase with the decrease of the output power. According to the exergoeconomic factor analysis, the exergoeconomic performance of the turbine and combustor among all the components can be enhanced by decreasing the investment and destruction, respectively. Next, the unit energy costs of different products in the output power range (100-20%) including electricity, cooling and heating energy for users, are calculated. The results show that the electricity increases faster than that of other products from 0.537 to 1.077 Yuan/kWh. Finally, the sensitivity analyses for the unit energy cost of the products are presented with different influencing parameters, such as the natural gas price, service life and discount rate. This exergoeconomic analysis may provide guidance for evaluating the products in distributed energy systems for energy networks.