Exergy cost allocation method based on energy level (ECAEL) for a CCHP system

A systematic method (ECAEL) is proposed for defining additional allocation equations and calculating the exergy cost of flows in thermal system. This method is based on the concept of the energy level, in which the continuous cost change within each component is considered. Thermoeconomic analysis using this method is carried out on a combined cooling, heating and power (CCHP) system, which consists of a gas turbine (TUR), an absorption chiller (ABC) and a heating water heat exchanger (HWHE). The thermoeconomic model for this system is defined to evaluate the productive relationships among the different components. The costs of all flows are calculated by solving the exergy consumption and allocation equations with design conditions. Moreover, a comparative analysis between proposed exergy cost allocation method and the conventional method is presented. As a result, the proposed method not only provides an accurate cost allocation output but also presents the dynamic cost of the flows within each component. Finally, the unit exergy cost is converted into the unit energy cost to evaluate the final products. According to this method, the unit energy costs of electricity ranks highest, followed by those of chilled water and heating water. The proposed method provides an option to complete the thermoeconomic analysis of multi-product systems.