Energy and exergy analysis of novel combined cooling and power (CCP) cycles

Abstract

This paper presents energy and exergy analyses of the basic combined cooling and power (BCCP) cycle as well as three modified CCP cycles. These modified CCP cycles are brought together by an appropriate combination of the organic Rankine cycles (ORCs) and ejector refrigeration cycle (ERC) to produce power and refrigeration, simultaneously. The performance of different working fluids for each CCP cycle is investigated using isobutane as a fixed working fluid of the ERC and R123, R245fa, and isobutane as working fluids of the ORCs. Energy and exergy analyses are conducted showing that the thermal efficiency, primary energy saving ratio (PESR), exergy efficiency, and overall exergy destruction ratio can be improved by 24.5, 134, 72, and 32% throughout the presented state-of-art modification as well as working fluid selection, respectively. Thus, selection of R123/isobutane as working fluid and CCP cycle incorporating both recuperation and turbine bleeding as cogeneration system are the most appropriate selection from thermodynamics and environment viewpoints. Moreover, exergy analysis demonstrated that the generator accounts for the major losses in the overall exergy destruction between all components. At the end, parametric study is conducted to examine the effects of different key thermodynamic parameters on performance of different cycles. It is shown that one can obtain a higher PESR by increasing of the generator pressure and ejector mass entrainment ratio or by decreasing of the evaporator pressure and condenser temperature. It is also found that increasing of the generator pressure and ejector mass entrainment ratio or decreasing of the evaporator pressure and condenser temperature will increase the thermal efficiency. Moreover, a higher exergy efficiency can also be obtained by increasing of the generator pressure as well as the ejector mass entrainment ratio.