How to set up a suitable vending machine

The temperature on both sides of the vending machine enclosure structure (or the inside and outside of the vending machine) is different, and along with the transfer of heat, the flow of moisture also moves. This movement of moisture is called infiltration of water vapor. It is difficult to block water vapor penetration. It is even more difficult than blocking the heat flow. The temperature difference between the two sides of the 　　 enclosure structure will form a partial pressure difference of water vapor, which constitutes the power of water vapor penetration. For example, the outer side (high temperature side) of the vending machine is 30°C, the partial pressure of water vapor when the relative humidity is 60% is 19.09mm Hg, and the low temperature side is 0°C, even when the relative humidity is 100%, the partial pressure of water vapor Only 4.58mm pump column. In this way, the partial pressure of water vapor on both sides of the enclosure structure is (19.09mm Hg-4.58mm Hg).　　 This is a considerable propulsion force than an ordinary fan with a pressure head of 30-60mm water column-due to this propulsion force. The water vapor can be forced through the cracks of the tiny pores of the enclosure structure into the vending machine. For low-temperature vending machines, this means that the moisture pressure enters the enclosure structure and the insulation layer. It has extremely adverse effects on the heat preservation of the vending machine.　　 is especially important for modified atmosphere vending machines, because in addition to water vapor entering the enclosure structure is not conducive to heat preservation, it will also cause gas changes in the vending machine, which is not conducive to the storage of fruits and vegetables. Under the promotion of the partial pressure difference of water vapor, the water vapor outside the vending machine will penetrate into the vending machine. When water vapor penetrates into the gas barrier of the enclosure structure. When the cold air reaches the dew point or freezing point temperature (especially in low-temperature vending machines), water vapor will condense into water droplets or ice crystals in the voids and gaps of the insulation material, which will make the insulation material damp and reduce the insulation performance , Because the thermal conductivity of ice is 2.0W/(M?K), which is about 100 times larger than the thermal conductivity of polyurethane of 0.02W/(M?K), it will destroy the thermal insulation layer in severe cases.