Refrigeration principle of the general refrigerator The function of the compressor is to compress the steam with lower pressure into steam with higher pressure, 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, causes the pressure to rise, and then sends it to the condenser, which is condensed into a higher pressure liquid in the condenser, and is throttled after the throttling valve becomes a pressure. After the low liquid is sent to the evaporator, it absorbs heat in the evaporator and evaporates to become a lower pressure steam, and then is sent to the inlet of the evaporator to complete the refrigeration cycle.
1. The basic principle of the refrigeration system
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 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.
2. Main components of the refrigeration system
The main components of the refrigeration system are compressor, condenser, evaporator, expansion valve (or capillary, supercooling control valve), four-way valve, double valve, check valve, solenoid valve, pressure switch, melting plug, output pressure regulating valve , pressure controller, liquid storage tank, heat exchanger, heat collector, filter, dryer, automatic shutter, shut-off valve, liquid injection plug and other components.
The condenser is one of the main heat exchange devices of the refrigeration unit. Its task is to discharge the high pressure superheated refrigerant vapor from the compressor, which is cooled by the heat released to the ambient medium, condensed into a saturated liquid, or even a supercooled liquid.
Our company currently has water-cooled and air-cooled type according to the cooling medium and cooling method used by the condenser.
(1) Air-cooled condenser
The air-cooled condenser uses air as a cooling medium to remove the heat of condensation by the temperature rise of the air. This type of condenser is suitable for applications where there is extreme water shortage or water supply, which is common in small Freon refrigeration units. According to different air flow modes, it can be divided into natural convection and forced convection.
1. The natural convection mode is only used in some domestic refrigeration equipment (such as refrigerators, air conditioners, etc.) where the cooling capacity is small, and the condenser is placed in the air circulation place. The temperature of the condenser surface is dissipated by natural ventilation. The air conditioning refrigeration system mainly uses mechanical forced ventilation convection to cool the gaseous refrigerant in the condenser pipe.
Forced convection air cooler, also known as chiller, is used for the heat transfer coefficient of the air duct air cooler. To enhance the heat exchange on the air side, it is often necessary to provide fins outside the tube to increase the heat transfer coefficient. However, under normal circumstances, after the rib tube is set, the flow resistance is small due to the small sheet distance, and measures must be taken to force the condition to pass through the rib tube family at a certain flow rate in order to obtain a better heat exchange effect.
Forced convection air-cooled condensers use a copper tube that penetrates the entire aluminum sheet (hence the tube fin condenser). The structural components are mainly U-bend heat transfer tubes, fins, small elbows, furcation tubes, inlet and outlet tubes, and end plates.
Note: The temperature of the hot air blown by the fan is higher, so the laboratory test room temperature control is ≤23-25 °C (the average temperature within 24 hours is ≤28 °C). If the density of the laboratory equipment is large, or the temperature of the laboratory cannot be controlled ≤23-25 °C (the average temperature is ≤28 °C within 24 hours), it is necessary to install the suction hood outside the fan to remove the hot air out of the laboratory to avoid affecting itself. The equipment and other equipment in the laboratory are used normally, and the principle is similar to a range hood.
(2) Water-cooled condenser
The water-cooled condenser uses water as a cooling medium to remove the heat of condensation by the temperature rise of the water. Cooling water is generally recycled, but a cooling tower or cooling pool is required in the system. Water-cooled condensers can be divided into shell-and-tube condensers and casing-type condensers according to their structural forms. Commonly, shell-and-tube condensers are used.
1. What is a cooling tower:
It is a device that uses water as a circulating coolant to absorb heat from a system and discharges it into the atmosphere to lower the water temperature; its cooling is accomplished by a water evaporation process, and the cooling water can be continuously recycled, from the economy. In terms of efficiency, it virtually reduces the waste of costs.
2. What is the cooling principle:
The cooling tower is cooled by spraying hot water onto the surface of the heat sink and contacting the moving air passing therethrough. At this time, the heat exchange between the hot water and the cold air is generated, and part of the hot water is evaporated, that is, the latent heat of evaporation in the evaporated water vapor is discharged into the air, and finally the cooled water falls into the air. In the water tank, it is pumped to the heat exchanger to absorb heat. The cooling tower needs to be separated from the condenser separately, and placed in an environment ventilated place (usually outdoor). The 10 ton cooling tower is connected to the condenser (water inlet and outlet pipes) with a diameter of 40 mm, and the water tower has a height of 1410 mm. 750mm in diameter