Virtual sensor for variable refrigerant flow AC system

In their article, Yabin Guo et al. propose a universal virtual variable-speed compressor power (VVCP) sensor for variable refrigerant flow (VRF) system based on 20-coefficient model. Energy consumption of air conditioning (AC) systems accounts for about 50% of energy consumption in building. Reducing the energy consumption of air conditioning systems – such as VRF systems which are widely used in buildings – is thus of great importance. The compressor power is the most important characteristic of the VRF system power consumption and is also an important parameter for AC system fault detection and diagnosis. However, for ordinary VRF system, the cost of measuring compressor power is high. The compressor power is obtained by the VVCP sensor using 3 input parameters (frequency, condensing temperature and evaporation temperature) which are measured by the system itself. Experimental evaluation shows that the mean square percentage errors (MSPE) are 9.9% under cooling conditions and 7.96% under heating conditions. The MSPE are 9.88% at steady state and 9.75% at dynamic state when the VVCP sensor is applied under 9 different refrigerant charge levels. The authors conclude that the proposed sensor can obtain compressor power with good accuracy under cooling, heating and non-standard refrigerant charge levels. It could be applied to operational monitoring, fault detection and diagnosis for VRF system at low cost. Read More