Performance Domain of Multiple-split Air Conditioning System

Multiple-split air conditioning (MSAC) system has become an attractive form of air-conditioning system for smallsized commercial and residential buildings. For a common room air conditioner, the only factor affecting the performance under a fixed outdoor and indoor condition is load rate of the indoor unit. But for the MSAC system, the indoor units will have quite different working situations under the same system load rate. It has been found that when the indoor and outdoor conditions (temperature and relative humidity) keep constant, the system COP will be within a “performance domain” related to the system load rate and the indoor load unevenness index. In this paper, the part load performances of MSAC systems are studied. As a result, it is found that whether the conditions changed, the performance domain will always exist. Through further analysis, it is pointed out that the shape of performance domain is related to the conditions, and the quantitative results are presented. This study is a theoretical foundation of design optimization, energy consumption prediction and evaluation in MSAC systems.