Comparative study on on-site performance testing of multi split air conditioning systems using air enthalpy difference method and compressor curve method

In recent years, multi split air conditioning systems have developed rapidly in China. Compared with traditional air conditioning systems, multi split air conditioning systems offer several advantages, such as strong independent control capabilities, significant energy-saving effects, high space utilization, flexible and convenient installation, and stable and reliable operation. However, testing the actual operational performance of these systems in engineering applications is relatively complex. The commonly used on-site testing methods are primarily the air enthalpy difference method and the compressor curve method. This study conducts an on-site measurement research using the two methods on a multi split air conditioning system installed in an office building located in the hot summer and warm winter zone in China. A comparative analysis of the accuracy of both testing methods is provided, aiming to develop more accurate and convenient approaches for testing the actual operational performance of multi split air conditioning systems. The results of the on-site tests show that due to the difficulty in directly representing the instantaneous operating conditions of the units through the measurement points and parameters of the air enthalpy difference method, this method exhibits a lag in responding to the dynamic behavior of indoor units. Therefore, the air enthalpy difference method is more suitable for periods of relatively stable operation of the system. In contrast, the compressor curve method, which directly tests the operating parameters of the refrigeration units, demonstrates better accuracy and dynamic responsiveness in measuring the cooling capacity of multi split systems and is applicable to various operating conditions.