Steady state simulation of heat pump type multi-connected air conditioning systems

The heat pump type multi-connected air conditioning system (heat pump VRF) is more complex in structure and control compared with the single-cooling VRF, so its performance simulation requires improvements in system description and solution algorithm. A steady-state simulation of the heat pump VRF is carried out in this paper. By using the diagonal elements of the adjacency matrix to reflect the working status of the components and transforming the adjacency matrix to switch cooling and heating modes, the structure of the heat pump VRF is described. According to the actual operation control strategy of the heat pump VRF, the model is solved using a refrigerant flow distribution algorithm based on the superheat/subcooling degrees. Compared with the experimental results, under rated cooling and heating conditions, the relative errors of the system capacity, power, and system energy efficiency predicted by the simulation of the heat pump VRF are all within 5%, and the system temperature and pressure errors are within ±3 ℃ and ±100 kPa, respectively, which means that the simulation results are accurate enough for heat pump VRF design.