Experimental study on the characteristics of radiation floor cooling system based on an earth–air heat exchanger

Radiation floor cooling systems (RFCSs) have no dehumidification capability and must be used with air handler systems. During summer, the shallow geothermal energy temperature is lower than the outdoor air dew point temperature. Using shallow soil for the heat exchange with outdoor air can effectively reduce the temperature and humidity of the outdoor air. Hence, using an earth–air heat exchanger (EAHE) instead of an air-handler unit (AHU), combined with RFCS, can eliminate the floor surface condensation. A physical simulation test bench was built, and RFCS and EAHE were first studied separately to observe the temperature and humidity characteristics of the room. Then, the two systems were coupled and the performance of the combined system was evaluated. The results reveal that the EAHE system can effectively reduce the air-humidity ratio in a room. The test data show that the temperature of the floor surface is approximately 26.5 °C, while the humidity ratio of the floor surface is significantly reduced to approximately 16 g/kg when the composite system is operated for 1 min. When the composite system runs for 30 min, the room temperature at heights below and above 0.5 m is within 22–23.5 °C and 23.5–24.5 °C, respectively. The humidity ratio of the floor surface is 12.74 g/kg. Hence, the composite system can considerably reduce the temperature and humidity of the room in the initial stage of operation. This research provides baseline information for addressing the challenges encountered with floor surface condensation.