Investigation on combining multi-effect distillation and double-effect absorption refrigeration cycle to recover exhaust heat of SOFC-GT system

Abstract

This study introduces the double-effect absorption refrigeration cycle (D-ARC) and multi-effect distillation with thermal vapor compression unit (MED-TVC) technologies to recover exhaust heat from the SOFC-GT system. This scheme can efficiently utilize waste heat at various temperature levels while enabling large-capacity cooling and freshwater production. The supercritical CO2 Brayton cycle is employed to facilitate the reliable operation of D-ARC and MED-TVC within their preferred temperature zones while enhancing the power output of the entire system. The techno-economic-environmental evaluation, comparative analysis and sensitivity analysis are performed to explore the feasibility of its engineering implementation. The proposed system obtains thermal, exergic and electrical efficiencies of 78.56 %, 65.41 % and 65.77 % with the total cost rate being 18.53 $/h and freshwater production 829.30 ton/year under design conditions, respectively. Exergy analysis indicates that SOFC and afterburner exhibit the highest irreversibility with values of 21.60 kW and 26.02 kW among all the components. Comparative analysis reveals that the system has exceptional thermal efficiency while exhibiting competitive advantages in electrical and exergic efficiencies compared to similar systems. Sensitivity analysis demonstrates that the electrical efficiency and net power output stabilize at their respective maximum values within the SOFC inlet temperature range of 514.3℃-528.6℃. Moreover, it is a promising option by increasing SOFC operating pressure and GT isentropic efficiency to enhance system efficiency and reduce CO2 emission. This work contributes to the development and waste heat recovery of the SOFC-GT system and other prime power units with similar exhaust gas temperature levels.