Modeling the impact of heat rejection from split air conditioner on outdoor air temperature in high-density residential areas

High-density residential areas can significantly restrict ventilation, leading to the accumulation of heat from split air conditioners within these spaces, which severely impacts the outdoor thermal environment and further exacerbates the heat rejection from air conditioners. This study aims to develop an outdoor temperature model that accounts for the impact of air conditioner heat rejection. A series of heat rejection calculation equations are established, and the concept of a heat storage space is introduced to develop a time-varying outdoor air temperature model. The model is validated through field measurements conducted in three high-density residential areas in Guangzhou. Results show minimum MAE, RMSE, and MAPE values of 1.22, 1.48, and 3.32 %, respectively. Owing to the high building density, Nanting Village recorded the lowest average COP, with a value of 2.08. The GDUT dormitory, due to the substantial indoor heat load, exhibited the highest air conditioning heat rejection and cooling energy consumption, with values of 285.55 W/m² and 59.41 W/m², respectively. In contrast, the AGILE gated community, benefiting from higher outdoor wind speeds and enhanced heat dissipation, achieved the highest COP of 4.36. Correlation analysis between COP and outdoor thermal parameters emphasizes the negative impact of outdoor heat accumulation on air conditioning performance. This study contributes to refining air conditioner heat rejection estimations and quantifying their impact on outdoor temperatures.