Simulation Study On Performance Of Inverter Multi-spilt Air-conditioning System Under Different Indoor Temperatures

In recent years, VRF air conditioning system has been widely used in publicbuildings and residential constructions. But VRF air conditioning system is verycomplicated and easily affected by many factors, including indoor and outdoorenvironment, the length of the pipes and so on. About indoor environment on theinfluence of the VRF system performance is not enough, so in this paper themathematical simulation model was established. The running performance parametersof the system was calculated and analyzed in order to provide guidance for theapplication of VRF system.The research subject of this paper is the multi-spilt air-conditioning system whichis installed in school of Environmental and Municipal Engineering of Xi’an Universityof Architecture and Technology. The mathematical model of the inverter compressor,condenser, electronic expansion valve and evaporator were established in MATLABlanguage. Based on the coupling relationships of all components, the performances ofthe multi-spilt air-conditioning system were studied and analyzed when the indoorsetting temperature was changed. And the importance of reasonably setting the indoortemperature to saving energy was also analyzed. The work is as follows:1. For VRF system, with the increase of the part load rate, EER increases. In thispaper, under standard cooling conditions, EER were studied at part load rate16%and24%. The results indicated that the EER under part load rate24%increased by2.4%compared with part load rate16%.2. On the premise of constant part load rate, with the increase of indoor settingtemperature, the actual power of inverter compressor decreases, and the actualrefrigeration capacity also reduces, but its EER increases. Under the cooling conditions, when the indoor air temperature is changed form19℃to27℃, the performances onpart load rate16%are studied. With indoor setting temperature increased, the actualpower of inverter compressor decreased from4.2kW to2.8kW and the actualrefrigeration capacity reduced from6.5kW to5.9kW, EER increased from1.5to2.1.3. Under the cooling conditions, the performance on part load rate24%is studied.One room indoor temperature is changed from19℃to27℃, the other room indoortemperature remains the same. Compared with part load rate16%, the actual power ofthe compressor increased from3.9kW to5.2kW, the refrigeration capacity increasedfrom6.2kW to10.3kW.At the same time, EER increased from1.8to2.1.In this paper, the research results show that indoor setting temperature hasimportant effect on VRF system. If the indoor setting temperature is too low, it will notonly make the EER reduced, but also increase energy consumption. By the way, it willaffect the human body thermal comfort feeling and cause bad effect to human bodyhealth. So I hope that the research in this paper will provide guidance for the use ofVRF air conditioning system.