[Refrigerated truck knowledge 4] Refrigeration system Do you understand?

With the rapid development of the social economy, the use of refrigerated trucks is becoming more and more common. However, the components and working principles of the refrigeration system of the refrigerated truck may not be known to everyone. The following is a detailed introduction for everyone.

In general, the refrigeration principle of the refrigerator is to compress the lower pressure steam into a higher pressure steam, so that the volume of the steam is reduced and the pressure is increased. The compressor draws in the lower pressure working fluid vapor from the evaporator, raises the pressure and sends it to the condenser, and condenses it into a higher pressure liquid in the condenser. After the throttling valve is throttled, the pressure becomes higher. After the low liquid is sent to the evaporator, it absorbs heat in the evaporator and evaporates to become a lower pressure steam, which is then sent to the inlet of the compressor to complete the refrigeration cycle.

First, the composition and use of components:

The refrigeration system consists of a refrigerant and four major components, namely a condenser, a compressor, an expansion valve, and an evaporator.

● condenser

The condenser is a heat exchange device, which uses the ambient cooling medium (air or water) to carry away the heat of the high-temperature and high-pressure refrigeration vapor from the cold compressor, and cools and condenses the high-temperature and high-pressure refrigerant vapor into a high-pressure normal temperature refrigerant. liquid. It is worth mentioning that during the process of changing the refrigerant vapor into the refrigerant liquid, the pressure is constant and still high pressure.

● Compressor

The compressor is the power of the refrigeration cycle. It is rotated by the motor and rotates continuously. In addition to timely extracting the vapor in the evaporator and maintaining the low temperature and low pressure, it also increases the pressure and temperature of the refrigerant vapor through compression to create a refrigerant. The condition in which the heat of the vapor is transferred to the external environment medium. The low-temperature low-pressure refrigerant vapor is compressed to a high temperature and high pressure state, so that the refrigerant vapor can be condensed by using normal temperature air or water as a cooling medium.

● Throttle element (ie expansion valve)

The high-pressure normal temperature refrigerant liquid is directly sent to the low-temperature scale evaporator without the ear, and the pressure of the refrigerant liquid is lowered according to the saturation pressure and the saturation temperature-corresponding principle, thereby lowering the temperature of the refrigerant liquid. The high-pressure normal temperature refrigerant liquid is passed through a pressure-reducing device, a throttling element, to obtain a low-temperature low-pressure refrigerant, which is then sent to the evaporator for heat absorption and evaporation. In the daily life, refrigerators and air conditioners are commonly used as throttling elements.

● Evaporator

The evaporator is also a heat exchange device. After the throttling, the low-temperature and low-pressure refrigerant liquid evaporates (boiling) into steam, absorbs the heat of the cooled substance, and lowers the temperature of the substance to achieve the purpose of freezing and refrigerating food. In the air conditioner, the surrounding air is cooled to cool and dehumidify the air. The lower the evaporation temperature of the refrigerant in the evaporator, the lower the temperature of the object to be cooled. In the refrigerator, the evaporation temperature of the general refrigerant is adjusted at -26 ° C ~ -20 ° C, and the air conditioner is adjusted at 5 ° C ~ 8 ° C.

Second, the principle of vapor compression refrigeration:

The single-stage vapor compression refrigeration system consists of four basic components: a refrigeration compressor, a condenser, an evaporator, and a throttle valve. They are connected in series by pipes to form a closed system. The refrigerant continuously circulates in the system, changes state, and exchanges heat with the outside world.

After the liquid refrigerant absorbs the heat of the cooled object in the evaporator, it is vaporized into low-temperature and low-pressure steam, sucked by the compressor, compressed into high-pressure high-temperature steam, discharged into the condenser, and sent to the cooling medium (water or air in the condenser). ) exothermic, condensed into a high-pressure liquid, throttling through a throttle valve into a low-pressure low-temperature refrigerant, and again entering the evaporator to absorb heat and vaporize, to achieve the purpose of circulating refrigeration. In this way, the refrigerant completes a refrigeration cycle through four basic processes of evaporation, compression, condensation, and throttling in the system.

In refrigeration systems, evaporators, condensers, compressors, and throttle valves are four of the essential components in a refrigeration system, where the evaporator is a device that delivers cooling capacity. The refrigerant refrigerates by absorbing heat of the object to be cooled therein. The compressor is the heart and acts to draw, compress, and deliver refrigerant vapor. The condenser is a device that emits heat, and the heat absorbed in the evaporator is transferred to the cooling medium along with the heat converted by the compressor work.

The throttle valve throttles the refrigerant, simultaneously controls and regulates the amount of refrigerant liquid flowing into the evaporator, and divides the system into two parts: the high pressure side and the low pressure side. In the actual refrigeration system, in addition to the above four components, there are often some auxiliary equipment, such as solenoid valves, distributors, dryers, collectors, fusible plugs, pressure controllers, etc., which are designed to improve operation. Economical, reliability and security are set.