THE INFLUENCE OF CHILLED WATER TEMPERATURE AND COOLING SURFACESON THERMAL COMFORT OF RADIANT COOLING SYSTEM

The influence of supply water temperature on the indoor thermal comfort of a radiant cooling system, i.e., a room with thermally activated glass fibre reinforced gypsum (TAGFRG roof) is studied. The supply water temperature is varied from 18 to 26°C with an interval of 2°C. The No Cooling (NC) case, i.e., the cooling system is shut down, is also investigated. A water chiller with a thermostat switch supplies water at the required temperature.
The surface (area) employed for cooling has a considerable impact on the performance of the radiant cooling system. The cooling area is increased by employing more surfaces(walls and floor) for cooling. The piping to each surface has an individual valve to control the flow rate of the chilled water. Four cases of cooling surface combinations are studied, namely, Roof only (R), Roof and Floor (RF), Roof, Floor and 2 Walls (RF_2W), and All Surfaces (AS). In the RF_2W case, chilled water is supplied to the north and south walls. NC case is also investigated. For R, RF, RF_2W and AS cases, the cooling surface areas are 9, 18, 31.2 and 47.4 m2, respectively. It is a well-established fact that an increase in cooling surface area would increase the heat transfer. In this study, the supply water temperature and the heat load are maintained at 20°C and 400 W (44.4 W/m2).

本研究探讨了供水温度对辐射冷却系统室内热舒适度的影响，具体而言，研究对象为一间设有热激活玻璃纤维增强石膏（TAGFRG）屋顶的房间。供水温度在18至26°C之间变化，间隔为2°C。此外，还研究了无冷却（NC）情况，即冷却系统关闭的情况。一个配备恒温开关的水冷机提供所需温度的水。冷却表面的（面积）对辐射冷却系统的性能有显著影响。通过采用更多用于冷却的表面（墙壁和地板），冷却面积得以增加。每个表面的管道都配备有个体阀门，以控制冷水的流量。研究了四种冷却表面组合情况，分别是：仅屋顶（R）、屋顶与地板（RF）、屋顶、地板与两面墙（RF_2W）以及所有表面（AS）。在RF_2W情况下，冷水供应至北墙和南墙。NC情况也进行了研究。对于R、RF、RF_2W和AS情况，冷却表面面积分别为9、18、31.2和47.4平方米。众所周知，冷却表面面积的增加会提高传热效率。在本研究中，供水温度和热负荷均保持在20°C和400W（44.4W/m²）。