Method to control an air conditioner by directly measuring the relative humidity of indoor air to improve the comfort and energy efficiency

In modern society, air conditioning systems are widely used in places where people tend to congregate, such as in homes, companies, schools and work sites. Both the dry-bulb temperature and relative humidity should be measured and controlled to achieve better comfort and to improve the energy efficiency of air conditioning systems. However, the current evaporation pressure control technique based on evaporator outlet pressure reading (EPCP) method only uses the dry-bulb temperature to control the evaporation pressure, making this method insufficient with regard to improving comfort. An evaporation pressure control approach based on the evaporator pressure and the relative humidity reading (EPCR) method is developed here. The EPCR method changes the evaporation pressure based on the dry-bulb temperature and the relative humidity of the air. The performance of an identical air conditioner is measured experimentally while switching the control method between the conventional EPCP method and the newly proposed EPCR method. The results demonstrate that the new EPCR method improves both the thermal comfort of indoor air and the energy efficiency.