1. What is the function of the evaporator in a refrigerated air dryer?
The evaporator is the main heat exchange component of a refrigerated air dryer. Compressed air is cooled and condensed into liquid water in the evaporator, thus drying the compressed air. Convective heat and mass transfer between the air and the low-pressure refrigerant vapor takes place in the evaporator. The liquid refrigerant, after passing through the throttling device, absorbs heat from the surroundings and transforms into refrigerant vapor, thereby cooling the compressed air.
2. Why are fins added to the outer surface of the evaporator's copper tubes?
Because convective heat exchange between the compressed air and the refrigerant vapor takes place in the evaporator. To achieve the best possible heat exchange effect, the heat exchange area on the compressed air side needs to be increased. Therefore, fins are added to the outer surface of the evaporator's copper tubes to increase the heat exchange area.
3. Why are most refrigerated air dryer evaporators horizontally oriented?
Because the condensation heat exchange of compressed air takes place in the refrigerated air dryer. For water vapor to condense into water droplets, a water film must first form on the outer wall of the copper tube. A horizontal arrangement allows the water film to quickly drip off in the form of droplets, renewing the heat exchange surface. A vertical arrangement would cause the water film to become thicker, affecting heat transfer.