Conversion of a Direct to an Indirect Refrigeration System at Medium Temperature Using R-134a and R-507A: An Energy Impact Analysis

Abstract

This work presents the experimental evaluation of energy consumption and refrigerant charge reduction when a commercial direct expansion refrigeration system is converted into an indirect system. The evaluation (with R-134a and R-507A) used a commercial cabinet with doors for medium temperature and a single-stage refrigeration cycle using a semi-hermetic compressor and electronic expansion valve; 24-h energy consumption tests were performed at laboratory conditions for each refrigerant and configuration at three heat rejection levels (23.3, 32.8 and 43.6 • C), maintaining an average product temperature inside the cabinet of 2 • C. The work analyses the impact of the conversion on temperature and pressure indicators, as well as, in the energy performance of each element. For R-134a the refrigerant charge was reduced in a 42.9%, but the energy consumption rose by 22.0%-22.8%; for R-507A the charge reduction was of 32.8% with an increase in energy consumption of between 27.7% and 38.7%.

Energy Evaluation of Multiple Stage Commercial Refrigeration Architectures Adapted to F-Gas Regulation

“…Sánchez et al [8], measured energy increments up to 14.0% when reconverting a R134a/CO 2 direct cascade to an indirect one using propylene-glycol at medium temperature. Llopis et al [9], presented an experimental evaluation of energy consumption reconverting a direct expansion refrigeration system to an indirect system, using R134a and R507A, with energy consumption increases up to 22.8% (R134a) and 38.7% (R507A).…”

Special Issue on Sciences in Heat Pump and Refrigeration

“…Liang et al [8] and Hu et al [9] presented the optimum design and a prediction model of heat exchangers. Other studies [10][11][12][13] reported various approaches for improving efficiency and to mitigate GHG emissions. All these studies are indispensable for continuous progress, and guarantee steady steps toward reducing direct and indirect emissions of GHGs.…”

Energy assessment and environmental impact analysis of an R134a/R744 cascade refrigeration plant upgraded with the low-GWP refrigerants R152a, R1234ze(E), propane (R290) and propylene (R1270)

“…This arrangement allows reducing substantially the refrigerant's leak rate up to 90% [17] as well as the amount of refrigerant used in the system [18]. However, indirect layout uses a fluid pump and an additional heat exchanger that increases the energy consumption of the refrigerating facility due to the power consumed by the pump and the extra temperature difference required in the secondary fluid cooler [19][20][21].…”