Investigation on the effects of nanorefrigerants in a combined cycle of ejector refrigeration cycle and Kalina cycle

Abstract

The main objective of this study is to carry out the thermodynamic analysis of a new power/ refrigeration combined cycle which consists of an ejector refrigeration cycle (ERC) and a Kalina cycle. In ERC, nanorefrigerants are used as the working fluid. Used nanorefrigerants are homogenous mixtures of different base refrigerants (R134a, R152a, R290) and nanoparticles (TiO2 and Al2O3) with 0-5 wt.% nanoparticle concentration. The effects of variation in system operational parameters (nanoparticle mass fraction, evaporator pressure, condenser pressure and superheating degree of motive flow) on energy efficiency and exergy efficiency of the combined cycle are reported. Additionally, net power production, refrigeration capacity, heat input to the combined cycle and their exergy contents are given for the case of TiO2/R290 nanorefrigerant use in ERC. This study is the first ERC analysis in which the effect of R152a and R290 base refrigerants and TiO2 nanoparticle use on ERC performance is investigated. The results show that as the nanoparticle concentration and evaporator pressure increase, the energy and exergy efficiencies also increase. On the other hand, with an increase in condenser pressure and the superheating degree of the motive flow, a decrease in energy and exergy efficiencies is observed. Under all the considered operational conditions of the combined cycle, the highest efficiency results are obtained for R290 and the lowest for R134a base refrigerants.