Experimental investigation on cooling performance of multi-split variable refrigerant flow system with microchannel condenser under part load conditions

On the basis of a 12.5 kW multi-split variable refrigerant flow (VRF) system, the nominal cooling capacity ratio (θ) and the COP of the baseline system with fin-tube heat exchanger (FTHX) and the VRF system with microchannel heat exchanger (MCHX) were obtained for different part load ratios (PLRs). The key control strategies of the VRF system were presented. The charged amount of refrigerant ratio β and the pressure drop ΔP of the MCHXs were also achieved. The experimental results show that the β of the MCHXs was decreased by 26.67-46.67% and the optimum charged amount of refrigerant of a VRF system with an MCHX should obtain a discharge pressure between 3.0 MPa and 3.15 MPa for PLR round 100%. The VRF system with the MCHXs obtained large ΔTHX to avoid refrigerant flashing expansion in long pipe application and it could provide residents with better thermal comfort in hot seasons or regions.