Proposed combined cold and power system integrated SOFC, sSCO2 power cycle and compression-absorption refrigeration with [Na(Tx-7)]SCN/NH3 as working fluid

A combined cold and power system integrated SOFC, sSCO2 power cycle, and compression-absorption refrigeration (CAR) is designed and optimized to utilize the high-temperature waste heat of solid oxide fuel cell (SOFC). On the premise of retaining the preheating capacity, the waste heat of the gas from after burner is first used to drive the sCO2 power cycle. The inlet temperature of compressor in sCO2 power cycle is appropriately raised to avoid the pinch point. The residual heat of sCO2 is used to drive CAR with [Na(Tx-7)]SCN/NH3 as working fluid. On the basis of the electrochemical reaction model of SOFC and the first and second laws of thermodynamics, the steady state characteristics are simulated by using the engineering equation solver. The reliability and energy balance of the model is verified. The optimizations, comparison, and exergy analysis are conducted and discussed. The optimal nCH4, TFC,in, and gamma SC are determined to be 0.004136 mol/s, 1029.1 K, and 2.5, respectively. The circulation ratio should be controlled within the range of 3.9 to 4.0. Comparison results reveal the exergy efficiency of the proposed system is higher than that of the SOFC/GT-ORC system by at least 0.035. The main reason for exergy destruction is due to the chemical reactions. The exergy destruction of the SOFC subsystem is the largest, which accounts for 73.7% of the total exergy destruction.

Automated summary

The integrated system of SOFC, sSCO2 power cycle, and CAR effectively utilizes high-temperature waste heat to improve overall system efficiency. By using waste heat from afterburner to drive the sCO2 power cycle, the system is able to optimize its performance and achieve higher exergy efficiency.