Simulation of recombined household multi-split variable refrigerant flow system with split-type air conditioners

In order to effectively utilize the outdoor units and minimize material waste and reinvestment in the replacement of split-type air conditioners by a new household multi-split variable refrigerant flow (VRF) system, a recombined household multi-split VRF system with original split-type air conditioners has been introduced in residential buildings. The equal frequency allocation principle and switching principle for three outdoor-unit operation modes have been determined for the recombined system. A universal model available for both the split-type air conditioner and the recombined household multi-split VRF system has been developed. The model was used for the design of the split-type air conditioners and the recombined system for a typical one-family household in three cities. Then, the cooling season energy performance of the split-type air conditioners and the recombined system were predicted by hourly calculation. According to the results, compared with split-type air conditioners, the recombined system can reduce the start-and-stop energy loss and work at higher compressor efficiency by optimizing the operation mode of outdoor units. The predicted energy saving ratio of the recombined household multi-split VRF system in the cooling season for the typical one-family household is 12.1%, 11.6% and 11.6% in Beijing, Shanghai and Guangzhou, respectively.