Performance Analysis and Optimization of an Air–Water Heat Pump System for Residential Applications in a Subtropical Monsoon Climate

Abstract An air–water heat pump was developed and tested for a centralized floor heating system, which provides hot water for four villas in a community located in a mid-latitude region of the Northern Hemisphere with a subtropical monsoon climate. The system's modular chiller unit consists of four compressor units, regulating the water temperature in the chiller's water tank, and it operates as part of an efficient centralized heating system. The heating control and defrosting strategies were determined by real-time and comprehensive energy efficiency ratios, along with the temperature difference between the outdoor heat exchanger and the ambient environment. Based on the test results of the outdoor unit, a suitable thermal system was selected, and a 93-day field test was conducted on the air–water heat pump during winter. Throughout the field test, the compression ratio (π) was maintained within a safe range of 2.67–5.79. Additionally, the daily average energy efficiency ratio ranged from 2.32 to 4.71, while the daily average heat capacity varied between 45.43 kW and 127.52 kW. The indoor temperature remained stable at approximately 19 °C, demonstrating the heat pump system's strong environmental adaptability and high energy efficiency under the given control principles.