Humidity conditions in rooms with air conditioning based on condensation dehumidification – determinants and limits

Abstract

Dehumidification by condensation is one of the ways to reduce the moisture content in the air. This method is often used in ventilation and air conditioning technology due to its availability. Cooling and dehumidifying the air is becoming a priority in many cases, which results from the observed climate changes. The article presents the results of calculations of the annual energy demand for air conditioning treatment on the example of Wroclaw. The main focus was on cooling and dehumidifying it due to the difficulty of maintaining the assumed air parameters in the internal space. The analyzes were carried out for three methods of controlling the operation of humidifiers, for different temperatures of the cooler wall from 3°C to 13°C, for various set temperatures in the range of 20-24°C and air relative humidity in the room in the range of 40-60%. The expected time during which internal thermal and humidity conditions are met by the operation of the ventilation system was determined. It was found that where the relative humidity should be kept low (e.g. below 50%) and at the same time the air temperature below 22°C, dehumidification of the air using vapour water condensation on the cooler walls may lead to a significant increase in the time of failure to meet the internal 
humidity conditions. This failure increases significantly when there is water vapour emissions in the room. In extreme cases, humidity conditions may be exceeded for more than 50% of the system’s annual operation time.