Thermal comfort is relevant to the performance and health of human in modern buildings, which has attracted public attention for a long time. Currently, air conditioning systems consume a great amount of energy as a result of creating comfortable environment, while human still experience discomfort.
Radiant cooling air-conditioning system has been a popular research hotspot for its simple structure, high energy efficiency and low annual operating cost. Many studies have demonstrated that the directly radiant heat exchanger could improve the thermal comfort levels and mitigate local discomfort compared with common convective air conditioning systems.
Radiant Heat Exchanger (RHE)：The front of heat exchanger is made into plane shape, the longitudinal rectangular fins are arrayed on the backside of the front panel and both sides of the back panel. The fins and panel constitute a series of air passages for enhancement of the natural convection heat transfer. Water as thermal storage medium. The refrigerant is compressed and fed into the condenser, then passed through the electronic expansion valve and evaporated by the RHE, and finally flowed back into the compressor. R410A is chosen as the refrigerant of this cooling system for its environmental friendliness.
During the testing period, all the PMV values with different indoor temperature are between -0.7 and 0.7, which indicate that the heat exchanger can supply acceptable thermal comfort. In the range of 0% to 6%, the indoor PPD values of the heat exchanger accounts for 43.8%, while it is 75% between 0% and 10% under different reference temperature, which can meet the standard recommended value. Comparative analysis on indoor temperature distribution of this system shows that the vertical temperature difference between head and ankle is less than the conventional air systems. |