Views:301 Author:Site Editor Publish Time: 2020-06-21 Origin:Site
Many large underground buildings in national defense projects are not allowed to use return air due to the storage of hazardous materials, and only new wind ventilation methods can be used. The environment in underground caverns is characterized by low temperature and high humidity. Due to the large enthalpy difference between the inside and outside of the caverns in summer, ordinary dehumidifiers do not have enough cooling capacity to control the fresh air dew point temperature to ensure that fresh wind do not condensation after entering underground caverns, which brings many problems to the design and operation of the ventilation and dehumidification system, so it is very necessary to develop a new wind dehumidifier dedicated to underground buildings. This article demonstrated that the ordinary dehumidifier cannot meet the operation requirements of the new wind system in the underground building cavern project, explained the key technology solved in the development of the new wind stepless load dehumidifier, and expounded the prototype design scheme and test results.
In summer, affected by the low temperature of the rock, the indoor wall temperature of the underground caverns is also low. Due to the infiltration of groundwater, the indoor wall surface has continuous moisture dispersion and the air relative humidity is high. In summer, the outdoor fresh air has a large moisture content and a high dew point temperature. If the dehumidifier cannot control the fresh air dew point temperature at sufficiently low level, the fresh air will condense when it enters the underground cavern, which will deteriorate the environmental conditions and cause various equipment damage due to moisture. In order to prevent this from happening, it is necessary to reduce the proportion of fresh air and make more use of return air. However, there are a large number of caves with special materials in the underground buildings of national defense engineering. Due to the problem of the emission of harmful substances and harmful gases, the return air method cannot be used, and the ventilation system can only be designed as a new wind method. This puts special requirements on the use of dehumidifiers.
In most areas of East China, Central China and South China, the calculated outdoor temperature of air-conditioning in summer is very high. In the design of the underground building ventilation system in these areas, according to the temperature and humidity conditions required by the process, the temperature of the cave wall and the heat and moisture ratio of the air in the cave, the air supply state of the new wind system is generally specified as tg = 20 ℃, φ = 60 %, the dew point temperature is about 12.7 ° C. Normally, when there is no process residual heat in the cave, the air supply status point can be moved along the equal d line to increase the air supply temperature to about 30 ℃ to overcome the heat transfer load of the cave wall. The dew point temperature of the supply air can change with the increase of the wall temperature and room temperature of the cave, but it must not be higher than the wall temperature. Only by controlling the dew point temperature can the new wind enter the cave and contact the wall surface of the cave without dew condensation. The wall surface of the cavern can maintain proper relative humidity even after getting wet and mixed.