One: What is a freezer? A refrigerator is a mechanical […]
One: What is a freezer?
A refrigerator is a mechanical device that uses a compressor to change the pressure change of the refrigerant gas to achieve low temperature refrigeration. The compressor used is different from the general air compressor due to its different use conditions and compression working medium. According to the difference in structure and working principle of the refrigerator, it is similar to the air compressor, and can also be divided into several different forms such as piston type, screw type and centrifugal type. Refrigerator is one of the important branches of compression refrigeration equipment
Refrigeration principle of low temperature freezer:
The single-machine vapor compression refrigeration cycle system constituted according to the principle of vapor compression refrigeration is composed of pipes of different diameters and components in which the refrigerant changes in different states, which are connected in series to form a closed circulation loop. Into the refrigerant, the refrigerant can circulate continuously in this circulation loop, which is called the refrigeration cycle system.
The refrigeration cycle system of the refrigerator is mainly composed of four components, namely the compressor, the condenser, the throttling element, and the evaporator. They are connected in series with pipes of different diameters to form a closed circuit that can circulate the refrigerant. system
The refrigeration compressor is driven by the motor to work, continuously sucking the refrigerant vapor in the evaporator, compressing it into high-pressure, superheated steam and discharging it into the condenser. It is precisely because of this high pressure that the refrigerant vapor is condensed. The heat is released from the device, and the heat is transferred to the surrounding environmental medium - water or air, so that the refrigerant vapor condenses into a liquid. Of course, the temperature of the refrigerant vapor when condensing must be higher than the temperature of the surrounding medium. The condensed liquid is still under high pressure and flows through the throttling element into the evaporator. In the throttling element, the refrigerant decreases from the high pressure at the inlet end to the mortgage, from high temperature to low temperature, and a small amount of liquid vaporizes into vapor. After the refrigerant flows into the evaporator, it absorbs heat in the evaporator and boils and vaporizes, gradually changing. In the process of vaporization, the refrigerant absorbs the required heat of vaporization from the cooled medium, and the cooled medium loses heat and reduces the temperature, thus achieving the purpose of refrigeration.
Three refrigeration system components
1. Refrigeration compressor: The refrigeration compressor is the power of the refrigeration cycle. It is driven by the prime mover, such as an electric motor. It not only draws out the vapor in the evaporator in time, maintains low temperature and low pressure, but also improves the refrigerant vapor through compression. The pressure and temperature create conditions for transferring the heat of the refrigerant vapor to the external environmental medium, that is, compress the low-temperature and low-pressure refrigerant vapor to a high-temperature and high-pressure state, so that the refrigerant vapor can be condensed by using normal temperature air or water as the cooling medium.
2. Condenser: The condenser is a heat exchange device. Its function is to use the ambient cooling medium air or water to take away the heat of the high-temperature and high-pressure refrigeration vapor from the refrigeration compressor, so that the high-temperature and high-pressure refrigerant vapor is cooled and condensed into high pressure and normal temperature. refrigerant liquid. The amount of heat that the condenser dissipates to the cooling medium is proportional to the area of the condenser, and is proportional to the temperature difference between the temperature of the refrigerant vapor and the temperature of the cooling medium. Therefore, to dissipate a certain amount of heat, a large enough condenser area is required, and a certain heat exchange temperature difference is also required.
3. Throttle element: The refrigerant liquid of high pressure and normal temperature cannot be directly sent to the evaporator of low temperature and low pressure. According to the principle of one-to-one correspondence between saturation pressure and saturation temperature, the pressure of the refrigerant liquid is reduced, thereby reducing the temperature of the refrigerant liquid. The high-pressure and normal-temperature refrigerant liquid is passed through the pressure-reducing device - the throttling element to obtain low-temperature and low-pressure refrigerant, which is sent to the evaporator to absorb heat and vaporize. At present, the commonly used throttling components in our chiller refrigeration system are expansion valves and capillaries.
4. Evaporator: The evaporator is also a heat exchange device. The throttled low-temperature and low-pressure refrigerant liquid evaporates (boiling) into vapor in it, absorbs the heat of the cooled medium, reduces the temperature of the cooled medium, and achieves the cooling effect. Purpose. The amount of heat absorbed by the evaporator is proportional to the area of the evaporator, proportional to the temperature difference between the evaporating temperature of the refrigerant and the temperature of the cooled medium, and of course, it is also related to the amount of liquid refrigerant in the evaporator. Therefore, if the evaporator needs to absorb a certain amount of heat, it needs a matching evaporator area, a certain heat exchange temperature difference, and a total amount of liquid refrigerant to the evaporator.
Four: There are two types of refrigerators: water-cooled refrigerators and air-cooled refrigerators.
The water-cooled freezer has a better cooling effect, but it needs cooling water. The air-cooled freezer is flexible and convenient, and does not require cooling water. It is suitable for use in water-deficient areas or mobile occasions.