Assessment of a Novel Combined Power and Refrigeration Cycle Using Solar Heat Source Based on the First and Second Laws of Thermodynamics

The present study proposes modified solar-driven combined power and ejector refrigeration cycles (CPERCs) for low-temperature heat sources. The proposed cycles are constructed from a combination of simple organic Rankine cycle (ORC), ORC with an internal heat exchanger (IHE), a regenerative ORC, and a regenerative ORC with an IHE, with an ejector refrigeration cycle (ERC). The ejector is driven by the exhausts from the turbine to produce more power and refrigeration, simultaneously. The three modified ORCs are introduced to improve the performance of the energy systems. The first and second laws of thermodynamics have been applied to each cycle using R245fa and isobutene as working fluids. Also, solar energy is utilized as the main heat source of the energy system. Concerning each proposed cycle, the thermodynamic model has been validated by previous works. Using isobutene as a working fluid, the maximum thermal and exergetic efficiencies have been obtained at 50.46 and 58.08 %, respectively, which corresponded to regenerative combined power and ejector refrigeration cycle with an IHE. In general, the thermal efficiency of a system is improved by 7.54 and 5.76 % through this state-of-art modification using R245fa and isobutene as working fluids, respectively. This demonstrated that isobutene can be a good candidate for CPERCs based on the first and second laws of thermodynamics. Throughout these modifications, cooling capacity and net produced power of cycles are also increased, successively. In all proposed cycles, the generator has the highest exergy destruction ratio, falling into the range of (29.82-34.73) and (22.9-25.93) kW for R245fa and isobutene, respectively.