Multi-climate energy and environmental feasibility analysis of an integrated heat pump system coupled free cooling and waste heat recovery for multi-scale data centers

Both free cooling and waste heat recovery in data centers are effective strategies for improving energy efficiency. This study develops an integrated heat pump system coupled free cooling and waste heat recovery, and analyzes its load and performance characteristics across seasons, climate regions, and data center scales. For data centers ranging from micro to ultra-large, Lhasa shows the highest annual average cooling coefficient of performance (COP), whereas Harbin exhibits the highest annual average heating COP. Micro data centers with 300 and 1,300 standard racks have lower annual average cooling and heating COP across all regions. In contrast, large data centers with 6,600 racks achieve 17.5% and 18.1% higher annual average cooling and heating COP, respectively. Considering both cooling and heating, Lhasa demonstrates the best system performance for small to ultra-large data centers, with the highest comprehensive COP of 4.67. For micro data centers, Harbin achieves the highest comprehensive COP at 4.22. Among the five cities, Lhasa shows the optimal carbon emission reduction performance, with a maximum reduction rate of 90.2% and an annual carbon dioxide emission reduction of 262,286 kg. The economic analysis conducted with the gas boiler system as the benchmark reveals that the integrated heat pump system achieves a payback period of no more than 6 years in all cities, with less than 2 years in Lhasa and Harbin. Dynamic performance, environmental and economic analyses indicate that the system can support data centers of all sizes, offering a practical solution to enhance energy efficiency and reduce carbon emissions.