Research on operation strategy of radiant cooling system based on intermittent operation characteristics

Abstract

Radiant cooling systems have become increasingly prevalent due to their great potential in comfort and energy saving. Nevertheless, their applications are limited by condensation and slow response. This study aims to explore the intermittent operation characteristics of radiant cooling systems and propose an effective operation strategy to improve system reliability. An operation strategy called standby cooling was proposed, and a none standby cooling scheme and four standby cooling schemes were simulated with the transient system simulation tool (TRNSYS). The results show that the none standby cooling scheme was difficult to satisfy the indoor comfort of the rooms with long shutdown periods. The indoor dry-bulb temperature and dew-point temperature when the air-conditioning mode is turned on have the approximate monotonic relationships with the maximum predicted mean vote (PMV) during the occupied period, and the Spearman correlation coefficient were 0.8809 and 0.8019, respectively. By contrast, with increased energy consumption, the standby cooling schemes can satisfy the comfort well and ensure the smooth operation of the radiant cooling system. With the same radiant system setting, the extra energy consumption of the schemes with continuous fresh air supply is 67.71%∼157.42% more than that of schemes that supply fresh air intermittently. With the same fresh air system setting, the schemes turning off the radiant cooling system need 11.67%∼71.41% more extra energy consumption than the schemes turning on the radiant system. Accordingly, from the perspective of energy consumption, one should turn off the fresh air system and turn on the radiant system as much as possible. This study provides a theoretical basis for understanding intermittent operation characteristics of radiant cooling systems and can direct the design and operation to enhance system reliability with less energy consumption.