Beginner's Guide to Refrigeration: Understanding Refrigeration Components and Fundamentals

February 23, 2024

      Beginner's Guide to Refrigeration: Understanding Refrigeration Components and Fundamentals


1. Refrigeration cycle system

It consists of four basic components: compressor, condenser, evaporator, and expansion valve.


2. Compressor

Inhale the vapor inside the evaporator to maintain its low temperature and pressure; Compress high-pressure and high-temperature steam. The higher the pressure, the higher the boiling point; The lower the pressure, the lower the boiling point. Only by increasing the pressure of the refrigerant and making its condensation point (boiling point) higher than the outdoor temperature can the refrigerant dissipate heat to the outside, reduce the temperature, and condense into a liquid.

3. Condenser

Cool the high-temperature and high-pressure steam discharged from the compressor into liquid; The heat released is carried away by water or air. It can be divided into three types: water-cooled, air-cooled, and water air mixed cooling.

4. Throttling expansion valve device

Throttling and pressure reduction; Adjust the flow rate. When the refrigerant fluid passes through a small hole, a portion of the static pressure is converted into dynamic pressure, and the flow rate rapidly increases, becoming turbulent flow. The fluid undergoes disturbance, friction resistance increases, and static pressure decreases, allowing the fluid to achieve the purpose of reducing pressure and regulating flow rate.

5. Thermal expansion valve

Connected to the inlet of the evaporator, the temperature sensing bulb is tightly attached to the outlet pipe of the evaporator. Another function of the expansion valve is to maintain a certain degree of overheating, prevent liquid shock and abnormal overheating.

The advantage of internal balance is that it does not need to be connected as a balance pipe, reducing the installation process of the unit and the number of fault points during the use of the unit, making it cheaper in price. The advantage of external balance is that the external balance thermal expansion valve accurately controls the outlet superheat of the evaporator, fully utilizes the heat exchange area of the evaporator, and improves the energy efficiency of the unit. If the pressure drop of the evaporator is high, an expansion valve with external balance should be used.

6. Electronic expansion valve

It adopts microprocessor control and is used in variable frequency air conditioning refrigeration systems to meet the needs of precise, high-speed, and large-scale load regulation. The electronic expansion valve adjusts the refrigerant heat at the outlet of the evaporator, and the opening of the expansion valve can be controlled by setting temperature and pressure sensors at the outlet of the evaporator; Electronic expansion valves can also be used for defrosting of heat pump units, compressor exhaust temperature control, etc.


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7. Evaporator

Evaporate liquid into gas; Absorb heat. Due to the continuous generation of condensate between the fins of the evaporator, which hinders the flow of air, the spacing between the fins of the evaporator is larger than that of the condenser. In addition, the surface of the evaporator fins also needs to undergo hydrophilic treatment (hydrophilic aluminum foil) to reduce the surface tension of the condensate and increase the cross-sectional area of the air flow.

8. Electromagnetic four-way directional valve

Components used for heat pump air conditioners. When the air conditioner operates for heating in winter, the indoor heat exchanger works as the condenser, while the outdoor heat exchanger works as the evaporator. This is exactly the opposite of when the air conditioner cools in summer, which requires the refrigerant flow direction to be opposite. The four-way directional valve consists of a pilot valve, a main valve, and an electromagnetic coil.


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9. Bidirectional solenoid valve

A bidirectional solenoid valve is a self-control valve used in refrigeration systems to perform on/off operations, which can control the flow and direction of refrigerant.

10. One-way valve

The function of a one-way valve is to only allow refrigerant to flow in one direction, and it is installed in the pipeline to prevent refrigerant gas or liquid from flowing back, so it is also called a check valve. In cold and warm air conditioning units, a one-way valve is used in conjunction with a four-way valve to safely and effectively switch the flow of refrigerant.

11. Globe valve

A shut-off valve is a type of pipeline shut-off valve that manually controls the opening and closing of the valve core to control the passage and shut-off of the flowing medium. Used at the end of pipelines, connecting various testing instruments and systems for filling and discharging; Used in pipelines to cut off fluid flow. Globe valves can be divided into two-way globe valves and three-way globe valves according to their structure.


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12. Drying filter

Absorb moisture from the refrigeration system, block impurities from passing through the system, and prevent ice and dirt blockages in the refrigeration system pipelines. The most easily clogged part of the system is the capillary (or expansion valve), so the drying filter is usually installed between the condenser and the capillary (or expansion valve).

13. Gas-liquid separator

Separate gaseous refrigerant from liquid refrigerant to prevent compressor liquid shock; Store refrigerant liquid in the refrigeration cycle and adjust the supply volume according to load changes.


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14. Optoscope

Installed in the liquid pipeline upstream of the expansion valve, it can observe the flow of liquid refrigerant and determine whether there is moisture in the refrigerant. If bubbles are seen, it indicates insufficient refrigerant or dirt in the pipeline. If there is water in the pipeline, the color displayed in the mirror changes from green to yellow.

15. Suction pipe filter

Mainly to prevent impurities or dirt from entering the compressor in the refrigeration system.

16. Hot gas silencer

Its purpose is to reduce the noise emitted by air conditioning during operation. Although it cannot be completely eliminated, it can achieve a reducing effect and is also a practical tool.

17. Oil separator

Separate the lubricating oil from the high-pressure steam discharged by the refrigeration compressor to ensure the safe and efficient operation of the device. According to the principle of oil separation by reducing airflow velocity and changing airflow direction, oil particles in high-pressure steam can be separated under the action of gravity


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18. Axial flow fan

The function of an axial fan is to cool the condenser. Generally installed outdoors, it can forcibly blow the heat emitted from the condenser towards the outside. The characteristics are high efficiency, large air volume, low cost, and energy-saving. The disadvantages are low wind pressure and high noise.

19. Centrifugal fan

The centrifugal fan is installed inside the window type air conditioner room and in the outdoor unit of the split cabinet type air conditioner. Its function is to suck in indoor air, cool it through the evaporator, and then compress it by the centrifugal fan impeller to increase pressure and send it along the air duct to the indoor area. The characteristics are compact structure, small size, high air volume, and relatively low noise.

20. Cross flow fan

Cross flow fans are usually used in indoor units with split wall mounted air conditioners. The blades are inclined forward, and the airflow flows radially into the impeller, passing through the interior of the impeller, and then exits radially from the other end.



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