Exergoeconomic analysis and optimization of innovative cascade bi-evaporator electricity/cooling cycles with two adjustable cooling temperatures

Abstract

This article works with performance improvement of the conventional combined cooling/power (CCP) cycles to augment energy and exergy efficiencies of the previous systems. For this target, a conceptual configuration of cascade ejector refrigeration system (CERS) is proposed and is joined with organic Rankine cycle (ORC) to generate power and cooling outputs. The introduced CCP system can generate cooling load at two various temperatures for freezing and air-conditioning usages. For power sub-cycle, basic ORC and recuperative ORC with turbine bleeding are selected as topping cycles. Thermodynamic and exergoeconomic assessments of the cycles are done, leading to provision of the working criteria of the systems. Also, an extensive parametric evaluation and single- and multi-criteria optimizations are conducted. With this regard, the optimum air-conditioning load, freezing load, net electricity, energy efficiency, exergy efficiency, and total sum unit cost of the product (SUCP) for the modified system are obtained 44.18 kW, 35.33 kW, 64.03 kW, 48.32%, 65.3%, and 404 $/GJ, respectively. More consequentially, the generator is clarified as the premier portion of destruction, followed by ejectors. Moreover, it is exhibited that the system’s SUCP can be decreased as generator pressure, heat source temperature, and condenser temperature increase, or evaporators superheated temperature and evaporators pressure decrease.