Start-up strategy analysis of capillary network radiant cooling-assisted fresh air system based on intermittent operation

Abstract

The capillary network radiation cooling system has received wide interest recently because of its high comfort potential, but the problem of condensation hinders its applications. In this regard, integrating a fresh air dehumidification system can effectively address the problem of condensation. Three start-up strategies of a capillary network radiant cooling-assisted fresh air system are proposed in this study, considering the typical initial working conditions in the Wuhan region. The optimal starting strategy of the coupled system is examined and discussed using numerical simulations. The results showed that under conditions of high temperature and high humidity, the strategy of opening the capillary tube only after the dehumidification of the fresh air system reaches 18 °C should be adopted. Under other conditions, the optimal strategy is to use the fresh air system to deliver both dehumidification and cooling until the dew point temperature of the attached layer attains 18 °C and then turn on the capillary network. Moreover, the synchronous start-up strategy of starting the fresh air system and opening the capillary network should be adopted under the conditions of high temperature and high humidity, and low temperature and high humidity. In this case, the temperature of the capillary water supply is controlled to decrease to about 18 °C at a temperature drop rate of 0.2 °C/min. For the high temperature and low humidity conditions, the water supply temperature should be controlled at a temperature drop rate of 1.2 °C/min, which can achieve a better anti-condensation effect. This study can provide theoretical guidance and supporting information for the actual start-up strategy of the coupled system under different indoor and outdoor temperature and humidity conditions.