Analysis of partial load operation characteristics for household multi-split system in the Yangtze River basin based on operation big data

The operation characteristics of household air conditioners in the Yangtze River basin have always been the focus of scholars’ attention. However, the previous research generally focuses on split-type wall-mounted or cabinet-type units, and the research on the partial load characteristics of household multi-split units is relatively lacking. Based on the operation big data of household multi-split units in the Yangtze River basin, the partial load operation characteristics of three typical cities in the Yangtze River basin are quantitatively analysed from the aspects of winter and summer, full-time, different periods, and different cities. Then, the influencing factors of the power of the multi-split system are analysed, and based on the coupling relationship between various influencing factors and the operation power of the units, a prediction model of the system power is developed, and the energy-saving potential of the household multi-split system is discussed based on this model. The results show that for the household multi-split system, the partial load rate between 30% to 60% accounts for the largest proportion in summer, reaching 48.4%, and the partial load rate of less than 30% accounts for the most in winter, reaching 59.7%. There are differences in the partial load characteristics of household multi-split systems in different seasons, different cities, and different periods. At the same time, the system load demand and the partial load rate of the system have the greatest impact on the system power. Based on the system power prediction model developed in this study, when the load demand is lower, the power of the 18, 16, and 14 kW units is adjusted to 16, 14, and 12 kW, respectively, the power of the cooling mode decreases by 7% to 13% in summer, and the power in the heating mode decreases by 3% to 22% in winter. Therefore, for the users who account for a large proportion of low-load operation time under certain environmental conditions, appropriately matching the slightly smaller unit capacity (increasing the partial load rate) will help the system save energy. The study conclusion can provide data support and reference for the performance development, operation control logic optimization, and equipment selection of household multi-split units.