Field test of multi-functional variable refrigerant flow system

摘要

In this study, a multi-functional variable refrigerant flow system operated in heat recovery mode with a water heating system was experimentally investigated. The multi-functional variable refrigerant flow system could supply space cooling, space heating, and hot water simultaneously in multiple zones. Its system performance with the water heating system operation was evaluated under a cooling main mode and a heating main mode. For the cooling main mode, when the water heating system was operated, the daily multi-functional variable refrigerant flow system performance was improved by 20.4%. This was mainly due to the increased heat recovery ratio from 0 to 0.1 and the reduced compressor pressure ratio. The pressure ratio was reduced by 16.5% because the condensing capacity was shared by both the water heating system and outdoor heat exchangers. For the heating main mode, when the water heating system was operated, the daily multi-functional variable refrigerant flow system performance was improved by 7.3%. This was mainly due to the increased part-load ratio of the system, which resulted in the increase of the compressor efficiency. The performance of the heat recovery mode between indoor units was also tested. It was found that the heat recovery operation could reduce discharge pressure by 22.2% and improve the hourly performance factor by 17%.