Study On Anti-Condensation Of Cabinet Based On Desiccant-Coated Metal Surface

For the metal cabinets placed in high humidity environment, dew point inside the cabinet increases due to environmental water vapor infiltration. At night when the cabinet wall temperature is lower than the dew point, then condensation happens. Condensation can seriously affect the operation and life of the equipment. The most commonly used anticondensation method is heating the air or removing moisture by using dehumidifier. These methods are not only complex, but also energyconsuming. In this paper, coating metal surface with silica gel was proposed. This method used passive hygroscopic properties of silica gel to prevent condensation occurring at night. The feasibility and performance of silica gel coating using to prevent condensation were analyzed through theoretical and experimental research. First, the actual cabinet was simulated by using the metal substrate coated silica gel and experimental system was set up to test its anti-condensation performance under conditions that the metal temperature was below ambient dew point. Then the heat and mass transfer coupling model of silica gel was established and used to predict the anti-condensation time. The results showed that silica gel coating can effectively delay condensation occurrence time which was mainly effected by ambient temperature, humidity and its own temperature. The established model given the relationship between occurrence time and the main factors. Based on the research and analysis of silica coating, silica gel coated metal cabinet was constructed and tested in the summer of Shanghai. The results showed that silica gel coating can effectively prevent condensation occurring. Silica gel coating adsorbed moisture at night which can effectively prevent condensation and regenerated during the day. For rainy day there was no solar radiation during the day and the humidity was high. Silica gel coating can effectively prevent condensation occurring within at least 48 hours. If the rainy days lasted for many days, the silica gel can’t effectively regenerate. After some time there was condensation occurring. Finally, the heat and mass transfer model of the metal cabinet was established. The effects of anti-condensation were simulated by changing the amount of silica gel, adding insulation and reducing emissivity. Cabinet wall temperature, air temperature and humidity inside the cabinet, dynamic absorption process and effective anti-condensation time were obtained through the simulation of different methods. The simulation results show that for high humidity nights adding insulation and reducing the emissivity can’t effectively prevent condensation. Silica gel coating method is simple and energy-saving, and the effective anticondensation time increases with the increase of silica gel amount per unit area. Combining adding insulation and reducing emissivity with silica gel coating can strengthen the effect of anti-condensation and ensure condensation does not occur for a longer period of time.