Effect of compressor speed on heat pump performance with climate-friendly refrigerants

The sustainability of the Heating, Ventilation, and Air Conditioning (HVAC) system focuses on reducing energy consumption, improving efficiency, minimising environmental impact, and improving indoor air quality while maintaining comfort. Sustainable HVAC practices are critical in combating climate change and creating energy-efficient systems. A Variable Refrigerant Flow (VRF) is an HVAC technology that utilizes high-efficiency components of variable-speed compressors enabled by inverter technology. These compressors adjust cooling output to actual demand and contribute to the system's overall energy efficiency, unlike conventional systems that operate at full capacity and use more energy. Thus, VRFs are highly efficient, adaptable, and suitable for various building types. The current study compares climate-friendly refrigerants R1234yf and R515B under different compressor frequencies (35, 40, 45, and 50 Hz). The experiment was carried out under the secondary fluid inlet and outlet temperatures of (12 °C/6 °C in the case of glycol and 45 °C/50 °C in the case of water), respectively. While the degree of sub-cooling and superheat is maintained at 5 °C and 10 °C, respectively. R1234yf demonstrated the highest refrigerant mass flow rate under the tested frequency, increasing compressor power consumption. R515B presents the highest system COP over all tested compressor frequencies, which can be selected as a suitable, safe, and non-flammable alternative refrigerant in buildings.