Heat and humidity control method of underground workshop
May 12, 2022
Heat and humidity control method of underground workshop
The temperature of the underground workshop is easy to control, and the humidity control has always been a problem that people pay attention to. The general dehumidification methods are as follows:
(1) Adsorption dehumidification. When the gas is contacted with a solid adsorbent, the moisture contained in the gas is adsorbed and the humidity is reduced. The humidity of the gas can be reduced to a very low level with proper selection of adsorbents and operating procedures. The adsorbent is recycled after regeneration, but the adsorption humidity range is small. This method is suitable for occasions with low humidity and high dehumidification requirements, and is not suitable for dehumidification in underground tall spaces.
(2) Absorb and dehumidify. The wet gas is brought into contact with some liquid with a low partial pressure of water vapor equilibrium, and the water vapor contained in the gas is absorbed and dehumidified. By choosing the appropriate absorbent, a gas with very low humidity can be obtained. The absorbent can usually be regenerated, and the commonly used absorbents are triethylene glycol, lithium bromide, concentrated sulfuric acid, etc. Its cost is higher.
(3) Compression dehumidification. The gas is compressed, thereby increasing the partial pressure of water vapor, correspondingly increasing the dew point, and then cooling it to condense the water vapor and dehumidify.
(4) Cooling and dehumidification. The wet gas is cooled in a partition heat exchanger. When the temperature drops below the dew point, some of the water vapor condenses into water or frost, which dehumidifies the gas. Depending on the degree of dehumidification required, cooling water or various frozen brines can be used as the coolant. This dehumidification method is commonly used in air conditioners or other similar devices. The advantages of these devices are stable performance and convenient use; the disadvantage is that the equipment cost and operating cost are high, and the heat transfer surface frost at low temperature will increase the thermal resistance. (5) Heat up and dehumidify. The gas is heated by a partition heat exchanger to reduce the relative humidity of the gas, which can be used in air conditioning, ventilation and other occasions. If the temperature is not allowed to rise, this method does not apply.
(6) Dehumidification by direct contact of gas and liquid. The gas is directly contacted with the liquid whose temperature is lower than the dehumidification point of the gas, and the water vapor contained in the gas is partially condensed into the liquid phase, and the gas is dehumidified. Although this method cannot obtain gas with very low humidity, its operating cost is very low, and it is especially suitable for dehumidification of a large amount of gas. In industry, except for occasions with high dehumidification requirements, this method should generally be preferred.
The walls of underground buildings emit water vapor all the time, and it is difficult for the generated water vapor to be discharged outdoors through natural ventilation. Therefore, underground buildings generally have the phenomenon of high humidity and low temperature. A dehumidifier can be used to discharge water vapor in the air to dehumidify and cool down, so that the air temperature is low. However, the human body has a certain range of adaptation to temperature changes. If the room temperature in summer is much lower than the outdoor temperature, it will make people feel uncomfortable. Therefore, the underground building not only needs to be cooled and dehumidified in summer, but also needs to be heated up at the same time after cooling and dehumidification, and also needs to be heated up after cooling and dehumidification in winter.
