CASE STUDY OF INVERTER AIR CONDITIONING LOGIC DURING OVERCHARGE REFRIGERANT

Özet

Preventative maintenance is a vital process for all mechanical machines. Known as routine or scheduled maintenance, it can be derived as a servicing and inspection activity aimed to prevent equipment from malfunction.  It is a critical process because it prevents any machines from facing a breakdown which will cause an operation interruption and disturbance. For residential air conditioning systems, routine maintenance must be performed based on the usage frequency where a higher usage means an increase in maintenance activity. There are several air conditioner system parameters that need to be monitored during the maintenance activity which include refrigerant charge pressure (psi), operation current (amp), voltage (V), indoor unit supply and return temperature (°C). However, for an inverter air conditioner, there are two additional parameters need to be considered which are temperature of the compressor (°C) and expansion valve opening frequency which is measured in pulse units (pls). However, these additional two parameters often been neglected which cause an overcharge of refrigerant level during an inverter air conditioner system maintenance activity. An overcharged refrigerant in an air conditioning system will cause a drop-in cooling capacity, increase energy consumption, and shorten the lifespan of the equipment. Main objective for this study is to observe parameter changes that occur on inverter air conditioners during an overcharge refrigerant state. The observed parameter includes compressor discharge temperature, expansion valve opening and compressor frequency. Finding a suitable air conditioner capacity done prior to the experiment starts by calculating the cooling load requirements for the experiment area. Once the cooling load is determined, the installation of an R32 inverter air conditioner takes place and observation for overcharge refrigerant data is recorded. During the experiment, the refrigerant is being pump into the system starting from 100% capacity until 140% capacity with 10% increment for each charge level. The average recorded data and the differences between each refrigerant charge level is calculated to determine the percentage change for all three parameters considered in this study. Based on this study, a 10% increase of refrigerant level in the system will cause a compressor discharge temperature to be reduce by 12%, a 32% reduced in refrigerant flow due to the closure of the expansion valve and the compressor frequency drops by 17%.