Numerical optimization of a transcritical CO 2 /propylene cascaded refrigeration-heat pump system with economizer in HT cycle

Abstract

Use of organic refrigerants such as Hydrochlorofluorocarbons and Chlorofluorocarbons have been criticized for their adverse impact on the Earth's protective ozone layer and for their significant global warming potential (GWP). CO 2 has been receiving great concern as an alternative refrigerant. Cascade refrigeration systems employing CO 2 are used for low temperature applications. Being a low critical temperature fluid CO 2 transcritical cascade systems offer low COP for a given application. Parallel compression economization is one of the promising cycle modifications to improve the COP of transcritical CO 2 cascaded systems. In this paper, transcritical CO 2 /propylene cascade system with parallel compression economization in the HT cycle has been analysed for cooling/heating applications. An enhancement in COP of 9% has been predicted. Thermodynamic analysis on R744-R1270 cascade refrigeration system has been performed to determine the optimal value of the various design parameters of the system. The design parameters included are: gas cooler outlet temperature and intermediate temperature in the high temperature circuit and evaporator temperature and temperature difference in the cascade condenser in the low temperature circuit.

Synthesis and luminescence study of BaZrO3:Eu3+ phosphor

“…The fluorescence light spectral profile as a function of the activator concentration was examined and the results indicated that the chromaticity coordinates of the overall emission light changed resulting in different colors of the overall emission light, for different concentrations as can be observed. The PL spectra is quite similar from our previous study on Eu 3þ doped Y 2 O 3 and SrY 2 O 4 phosphor and the prepared phosphor shows good results as compared to our previous work [26,29,33]. 3.6.…”

Thermodynamic performance evaluation of the CO 2 parallel compression supermarket refrigeration system with a subcooler

“…The effectiveness of the subcooler 30 . can be defined as the ratio of temperature difference between two streams of fluid in the subcooler: …”

Effect of subcooling and superheating on performance of a cascade refrigeration system with considering thermo- economic analysis and multi-objective optimization

“…For design parameters, thermal performance calculated for different combinations of design parameters and optimum performance parameters such as COP max , T opt and mass flows of R744 and R1270 evaluated. At the another work [15] numerical optimization of a transcritical R744 /R1270 cascade refrigeration -heat pump system with economizer in HT cycle carried out. At this work by using parallel compression economization in the HT cycle as the modification to improve the COP of transcritical cascaded systems, simulation for cooling/heating applications carried out.…”