Model-based commissioning for filters in room air-conditioners

This paper proposes a model that can estimate filter resistance using estimated air-conditioner indoor unit air flow rate, which is tightly related to filter fouling conditions. Two sorts of value are used as inputs to estimate air flow rate. One is the power consumed by the fan in the indoor unit of a room air-conditioner and the other is the thermal performance of a room air-conditioner. For the room air-conditioners that the real-time indoor unit fan power consumption is available, fan power consumptions are used as inputs to estimate filter resistance. For the room air-conditioners that are equipped with refrigerant pressure and temperature sensors, this model estimates filter resistance using refrigerant pressure and temperature, air temperature or enthalpy difference between supply and indoor air. This model was validated using a really running multi-evaporator Gas-engine Heat Pump (GHP) system. The maximum and average difference between estimated and measured filter resistance are 12.72% and 5.89% when using the fan power consumption as inputs. When using the air-conditioner thermal performance data, the maximum and average estimation errors are 13.12% and 5.96%. The validation results show that this model is accurate enough for estimating filter resistance. Based on this model, the method for commissioning filters in air-conditioner is discussed. This method is useful for automatically estimating filter resistance and reminding users timely to clean or replace a filter to prevent wasting energy and to maintain desirable indoor environment.