The vacuum pump uses the periodic change of the volume of the pump cavity to complete suction and exhaust to achieve the purpose of suction. This kind of pump is divided into reciprocating type and rotary type.
best vacumm pump to vacuum pumping
Vacuum pumping is an essential process before filling refrigerant in the process of production or maintenance of refrigeration equipment. That is to say, the vacuum pump is used to connect with the refrigeration system pipeline (generally, the high and low pressure sides are connected at the same time) to remove the non condensable gas and water in the system pipeline.
1. Remove the non condensable gas in the system: the existence of the non condensable gas will increase the condensing pressure and exhaust temperature of the system, which will affect the refrigeration effect; it may also cause the carbonization of the lubricating oil at high temperature, endanger the normal operation of the compressor, or even burn the compressor motor.
2. Remove the moisture in the system: moisture is the biggest killer in the refrigeration system (especially Freon system in the vapor compression refrigeration cycle). First, the interaction of lubricating oil and moisture will generate acid, which will corrode the system, and at the same time cause the phenomenon of “copper plating” and damage the compressor. At the same time, moisture will cause ice in the valve port or capillary of expansion valve and “ice blockage”.
best vacumm pump to vacuum principle
1. After the vacuum pump is started, the non condensable gas and water vapor in the system are extracted first, and then only water molecules (liquid) are left.
2. With the increase of vacuum degree, the absolute pressure in the system decreases. When the absolute pressure in the system decreases to the saturated water vapor pressure corresponding to the ambient temperature, the remaining water molecules in the system boil into water vapor and are continuously extracted. It should be noted that during the process of vacuum extraction, under normal operation, the temperature in the system is consistent with the ambient temperature. This is also the reason why the lower the ambient temperature is, the harder it is to vacuum and the slower the speed is.
It is well known that the residual gas in the process of vacuumizing is mainly caused by water vapor in the process of vacuumizing to the specified limit pressure in the high vacuum area.
Once any water vapor is introduced into the system, it must be removed to the specified residual concentration. Pumping long enough and accepting a “natural” desorption rate will work, but this discussion begins with the need to reduce the pumping time. The only solution is to desorb water faster and provide sufficient pumping speed to meet the gas load of higher desorption rate. This means that energy must be applied to the adsorbed water bed.
In the pumping process, mechanical energy can be applied in the roughing cycle by venting in the dry gas. The exhaust gas affects the adsorbed water molecules and essentially disperses them. If the pressure is kept high enough, the desorbed water will be brought into the air flow of the crude pump for entrainment.
The difference between each system is large enough that some experiments are needed to get the maximum effect, but keeping the pressure under a few torches for a few minutes is a good starting point. In terms of total water removal, this technology is not as good as the following technologies, but it will remove a large amount of water, which may be enough for many processes.