Based on the dehumidification technology employed, the primary operating principles of moisture-proof cabinets can be broadly categorized into electronic (physical adsorption/molecular sieve), semiconductor condensation, nitrogen-purged (nitrogen cabinets), and compressed air types. Electronic moisture-proof cabinets utilize highly efficient hygroscopic materials (such as 4A molecular sieves) to adsorb moisture within the cabinet; once saturated, the moisture is vaporized via heating and expelled from the cabinet, thereby regenerating the desiccant. This process involves an intermittent, cyclical dehumidification operation controlled by a shape-memory alloy valve that regulates the opening and closing of the exhaust port. Advantages of this method include exceptional energy efficiency, ease of use, and a maintenance-free design. Furthermore, since the adsorption and desorption of moisture constitute a physical reaction, the desiccant can theoretically be reused indefinitely; additionally, the molecular sieves continue to adsorb moisture even in the event of a power outage. Disadvantages include a relatively slow rate of humidity reduction, a rise in internal cabinet temperature during the moisture expulsion phase, a comparatively bulky dehumidification module, and lower precision in humidity control; moreover, a brief period of moisture "rebound" (a slight rise in humidity) may occur within the cabinet immediately after the heating and expulsion cycle concludes and the valve closes.
Semiconductor condensation moisture-proof cabinets employ a semiconductor cooling module to lower the temperature of humid air flowing across a condensing plate to below its dew point. This causes water vapor to condense into liquid droplets, which are then collected and drained away. The advantages of this method include lower manufacturing costs, minimal heat generation, a compact footprint, precise humidity adjustability, and low operational noise levels. Disadvantages include a relatively slow dehumidification rate; susceptibility to freezing on the condensing plate-which impairs dehumidification efficiency-when the ambient temperature drops below 16°C; and a significant risk of severe "moisture rebound" (where condensed water re-evaporates back into the cabinet) in the event of a power failure. Additionally, the service life of the semiconductor module is relatively short, and the unit requires a continuous power supply to function.
Nitrogen-purged moisture-proof cabinets (nitrogen cabinets) operate by injecting liquid nitrogen or high-pressure, high-concentration nitrogen gas-which inherently possesses very low humidity-into the cabinet to displace the existing humid air, thereby creating a low-humidity, low-oxygen internal environment [1-2]. Advantages of this method include rapid dehumidification and the effective prevention of oxidation in stored items. Disadvantages include the high cost of nitrogen gas and the difficulty in consistently achieving ultra-low humidity levels-typically below 10% RH or 5% RH-using standard nitrogen supplies; furthermore, driven by technological advancements, certain applications with highly stringent requirements have begun to transition toward alternative dehumidification technologies.
Compressed air moisture-proof cabinets function by compressing, drying, and filtering external air before injecting it into the cabinet to displace the humid air currently contained within. The advantages include rapid dehumidification, a quick recovery time for humidity levels after the door is opened, and the theoretical capability to achieve humidity levels below 1% RH. Disadvantages include high energy consumption and operational noise; the potential for compressed air to introduce impurities-such as metal shavings, rust particles, and oil residue-that contaminate the interior environment; the requirement for specialized filtration, drying equipment, and piping, which renders the unit difficult to relocate; significant susceptibility to fluctuations in external ambient humidity; an inability to maintain conditions during sudden power outages; and the inherent risk of equipment corrosion.