A comprehensive thermodynamic analysis of a novel CHP system based on SOFC and APC cycles

Abstract

A novel combined system driven by SOFC is proposed in this paper. The presented system is an integration of SOFC, modified APC, and DHW systems, which is designed in two different configurations for heating and power generation aims. To illustrate the practicability of the suggested systems, the energy and exergy analysis are carried out. The results of the modeling reveal that the combination of SOFC-APC-DHW results in an enhancement in the energy efficiency from 47.78% to 60.05% compared to standalone SOFC cycle. The exergy efficiency is also enhanced from 46.09% to 49.58% for the SOFC-APC-DHW arrangement. Moreover, the APC net power and DHW heating load are obtained 54.06kW and 162.9kW for the SOFC-APC-DHW case. Among all components, preheater 3 (PH3) holds approximately 25% of total exergy destruction rate, and SOFC stack contributes to about 17% of the total exergy destruction. Furthermore, a parametric study is performed to inspect the effect of various thermodynamic parameters on the significant criteria. According to the parametric study, it resulted that higher energy efficiency is obtainable by increasing the generator pressure and absorber LiBr fraction or by decreasing absorber temperature and steam to carbon ratio. Moreover, the exergy efficiency of the system can be enhanced by reducing the current density of the SOFC system, compressor pressure ratio, steam to carbon ratio, and absorber temperature.