Dingxuan Li, Yiji Lu
The application of heat pump systems is of great significance for energy consumption and emissions reduction. This article investigates a novel flexible heat pump system and conducts a comprehensive energy, economic, and environmental assessment of it. By analysing meteorological data of Glasgow, a typical heat load curve is established, and the study is conducted based on this curve, with comparisons made to a baseline two-stage heat pump system. Energy analysis shows that the flexible heat pump system achieves its maximum SCOP improvement at 8 °C, with increases of 14.06% for R134a and 11.05% for R1234yf compared with the baseline system. Economic assessments indicate that, despite higher initial investment costs, the flexible system's lifecycle cost (LCC) is lower than that of the baseline system, with savings of approximately £1011 and £776 for R134a and R1234yf, respectively, and payback periods of approximately 10.5 years and 11.0 years. Regarding environmental analysis, the flexible system lowers lifecycle CO 2 emissions for both refrigerants, with the greatest reductions achieved when combined with low-GWP fluid R1234yf. Overall, the integration of system flexibility with low-GWP refrigerants demonstrates a practical pathway toward a cleaner energy future and sustainable energy transitions, combining enhanced efficiency, cost-effectiveness, and climate benefits. • Flexible two-stage heat pump with PCM storage enhances energy efficiency. • Dynamic mode control improves system adaptability and seasonal performance. • Heat load curve derived from long-term meteorological data. • Low-GWP refrigerants reduce greenhouse gas emissions and improve sustainability. • Life-cycle cost analysis shows economic benefits over conventional systems.