Comparative Investigation on Thermo-economic Performance between ORC and LiBr Absorption Refrigerating Cycle in Waste Heat Recovery

Abstract

Abstract With annual net profit of system as the objective function, the thermo-economic performance comparison between subcritical organic Rankine cycle (ORC) and LiBr absorption refrigerating cycle under different local electricity or cooling price and heat source conditions was conducted. Results show that, the thermo-economic performance of LiBr absorption refrigerating cycle and ORC using zeotropic mixture as working fluid are better than that of ORC using pure working fluid at any heat source temperature Tgi, heat source mass flow rate mg, local electricity price Se or cooling price Sc. There exist critical Tgi (Tgi,cr), critical mg (mg,cr) and critical Se (Se,cr) at which the economic benefit of ORC using zeotropic working fluid and refrigeration cycle is equal. If Tgi (or mg or Se) is lower than Tgi,cr (or mg,cr or Se,cr), the refrigeration cycle is prior, on the contrary, the ORC using zeotropic working fluid is preferential. The Tgi,cr, mg,cr and Se,cr are all increasing with the augment of the ratio of Sc to Se.