Experimental study on cooling feasibility and indoor thermal comfort of multi-connected dry capillary radiant air conditioning system[A case study on feasible performance of a system combining an airbox convector with a radiant panel for tropical climates]

The traditional capillary radiant air conditioning system with water as heat exchange medium in the indoor unit may have defects of water leakage, pipeline freezing in winter and time delay of cooling and heating effect. It can only achieve good cooling or heating comfort, which is related to the installation of radiant capillary or panel in the floor or ceiling. In view of these defects, this work proposes a multi-connected dry capillary radiant (MDCR) air conditioning system with refrigerant as heat exchange medium. For the cooling operation, the fan coil assisted capillary radiant cooling (FCR) is developed. The fan coil bears part of the sensible cooling load to improve cooling effect and undertakes the entire latent cooling load to dehumidify the air to avoid the condensation. Two operation modes including the capillary radiant cooling (CR) and the FCR were comparatively tested. The test results show that the FCR can maintain the indoor temperature at 19–22°C, a comfortable temperature range, and can dehumidify the air to prevent the condensation. The experimental results demonstrate the application feasibility of MDCR for radiant cooling. In addition, the FCR can maintain the comfort relative humidity at 74–80% during the whole process of the refrigeration operation. The thermal comfort indices of predicted mean vote (PMV) and predicted percentage dissatisfied (PPD) can be kept at −0.5 ~ 0.5 and 0–10% at different heights of the indoor room. It can be concluded that FCR can achieve good thermal comfort and the indices of PMV and PPD can reach Class I standard.