Experimental Investigation of System Performance, Energy Efficiency, and Total Equivalent Warming Impact of R-404A and Low-GWP R-448A in a Commercial Refrigerated Display Cabinet

Author : Chien Yu Lin

Abstract : Background and Motivation: The global phase-down of high-Global Warming Potential (GWP) hydrofluorocarbons under the Kigali Amendment to the Montreal Protocol has placed increasing pressure on commercial refrigeration systems to adopt lower-GWP alternatives. R-404A, a widely used refrigerant in commercial refrigerated display cabinets, has a GWP of 3922 and is a primary candidate for replacement. R-448A, an HFO/HFC blend with a substantially lower GWP of 1273, has been proposed as a practical drop-in alternative. However, refrigerant substitution should not be evaluated on GWP alone; system performance, energy efficiency, compressor discharge conditions, and the resulting lifetime climate impact must also be quantified before a replacement can be recommended for widespread commercial adoption. Research Objectives: This study experimentally compares R-404A and R-448A in a commercial refrigerated display cabinet, with R-449A included as an additional low-GWP comparison refrigerant. The specific objectives are: (1) to compare the coefficient of performance (COP), compressor power consumption, and discharge temperature of R-404A and R-448A under identical operating conditions; (2) to evaluate the technical feasibility of R-448A as a replacement while maintaining comparable cooling capacity; (3) to assess the environmental implications of R-448A from both refrigerant-GWP and electricity-consumption perspectives through a Total Equivalent Warming Impact (TEWI) framework; and (4) to use R-449A as a reference point for interpreting the performance of lower-GWP HFO/HFC blends. Experimental Setup and Methodology: A modular commercial refrigeration test platform was constructed, comprising a compressor, condenser, electronic expansion valve (EEV), evaporator/ display cabinet, and refrigerant piping, instrumented with temperature and pressure sensors and a power analyzer for compressor power measurement. The EEV maintained the target superheat to enable a consistent, bias-minimized comparison among refrigerants. All refrigerants were tested under identical conditions: an evaporation temperature of −18°C, a condensation temperature of 40°C, a superheat of 5 K, and a subcooling of 2 K. System COP was defined, per the first law ofthermodynamics for the vapor-compression cycle, as the ratio of evaporator cooling capacity to compressor input power (COP = Qe / Wcomp). A TEWI framework was further established to combine direct refrigerant emissions (from leakage and end-of-life losses) with indirect emissions from electricity consumption: TEWI = (GWP × L × n) + [GWP × m × (1 − α)] + (Eannual × β × n), where L is the annual leakage rate, n is equipment lifetime, m is refrigerant charge, α is the end-of-life recovery rate, Eannual is annual electricity consumption, and β is the electricity emission factor. Because the source dataset did not report all lifetime parameters, a transparent scenario analysis was applied using explicitly stated assumptions (refrigerant charge of 1.6 kg, 8,000 h/year operation, 10% annual leakage, 10-year equipment lifetime, 90% end-of-life recovery, and an electricity emission factor of 0.466 kgCO₂e/kWh), clearly separated from the measured performance data. Results and Discussion: The measured COP values for R-404A, R-448A, and R-449A were 1.54, 2.37, and 2.98, respectively, indicating that R-448A achieved a COP approximately 53.9% higher than R-404A under the tested conditions. Average compressor power consumption decreased from 655.25 W for R-404A to 584.74 W for R-448A, a reduction of approximately 10.8%. Discharge temperature was also lower for the alternative refrigerant — 93.05°C for R-448A versus 95.30°C for R-404A — indicating no increase in compressor discharge thermal load. Cooling capacities of R-448A and R-449A both remained within ±5% of the R-404A baseline, an important result for retrofit applications where large capacity penalties would otherwise necessitate extended run times or larger equipment.Extending the measured results to a scenario-based lifetime assessment, the estimated annual compressor electricity consumption at 8,000 h/year of operation was approximately 5,242 kWh for R-404A versus 4,678 kWh for R-448A (a difference of about 564 kWh/year). Under the stated 10-year baseline scenario, estimated TEWI was approximately 31.33 tCO₂e for R-404A compared with 24.04 tCO₂e for R-448A — a reduction of about 7.29 tCO₂e, or roughly 23%. These scenario results, clearly distinguished from directly measured quantities, illustrate that R-448A's combination of lower GWP and lower compressor energy consumption can meaningfully reduce both direct and indirect lifetime climate impacts. Conclusions: Under identical commercial-refrigeration operating conditions, R-448A demonstrated a 53.9% higher COP, a 10.8% lower compressor power consumption, and a lower discharge temperature relative to R-404A, while maintaining cooling capacity within ±5% of the baseline. The scenario-based TEWI analysis further indicates a potential 10-year lifetime emissions reduction of approximately 23% when replacing R-404A with R-448A in a representative commercial refrigerated display cabinet. Taken together, these experimental and scenario-based results support R-448A as a technically feasible and environmentally favorable transition refrigerant for commercial refrigeration systems currently operating with R-404A. Future work should extend the experimental matrix to multiple ambient and evaporation temperatures and refrigerant charge levels, measure full-system electricity consumption (including fans, defrost heaters, and controls), and replace scenario assumptions with field-measured leakage rates, equipment lifetimes, and end-of-life recovery rates.

Keywords : R-404A, R-448A, low-GWP refrigerant, commercial refrigerated display cabinet, coefficient of performance, energy efficiency, Total Equivalent Warming Impact (TEWI)

Conference Name : International Conference on Environmental Heat Transfer and Sustainable Cooling (ICEHTSC - 26)

Conference Place : Osaka, Japan

Conference Date : 7th Sep 2026