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Refrigerators have become an indispensable appliance in many households for food preservation. To operate and maintain this device efficiently, as well as conserve energy during usage, it's essential to have a basic understanding of its structure and operational principles.
1. Structure and Operation Principles of Refrigerators
Refrigerators have evolved into an essential household item for preserving food. To operate and maintain this device efficiently, as well as conserve energy during usage, it's crucial to have a basic understanding of its structure and operational principles.
Basic Structure of Refrigerators
A typical refrigerator is composed of main components: the condenser, compressor unit (Block), refrigerant (gas), and evaporator coil.
- Condenser:
It serves as a heat exchanger, with one side containing the refrigerant (cooling gas) that condenses - The refrigerant is a circulating substance in the refrigeration system, absorbing heat from the cooling chamber by evaporating at low pressure and temperature, and releasing heat to the environment at high pressure and temperature - the other side being the cooling medium (water or air).
The primary task of the condenser is to release the heat of the condensed refrigerant into the environment.
The condenser is usually installed in a way that one end (input end) is connected to the discharge end of the compressor, and the other end (liquid refrigerant outlet) is connected to the filter dryer before joining the suction tube.
The condenser is typically made of iron, copper, and has heat-dissipating fins.
- Compressor Unit (Block):
Refrigerators are often equipped with a single or twin-piston compressor, utilizing a crank mechanism to convert rotary motion into reciprocating motion back and forth of the pistons.
The tasks of an air conditioner compressor unit usually include:
+ Drawing in the refrigerant vapor produced at the evaporator coil while maintaining the necessary pressure for vaporization at low temperature.
+ Compressing the vapor from evaporative pressure to condensation pressure and pushing it into the condenser coil.
- Refrigerant (Gas):
It is a liquid that easily vaporizes placed in the refrigerator to create a cold temperature. Many refrigeration systems use pure ammonia as the refrigerant. Its boiling point is about -27 degrees Celsius (approximately -32 degrees Fahrenheit).
- Evaporator Coil:
It is a heat exchange device with one side containing the refrigerant and the other side the environment to be cooled. The evaporator coil's task is to absorb heat from the cooling environment and provide it to the refrigerant to boil at low temperature. It is installed after the expansion valve or throttle valve, before the compressor in the refrigeration system.
Working Principle of the Refrigerator:
The refrigerator utilizes dry water vapor to absorb heat. Although it sounds simple, the working mechanism of the refrigerator is relatively complex, with various components playing crucial roles in the refrigeration cycle.
The basic operating principle of the refrigerator can be divided into 4 steps as follows:
Step 1: Compression of Gas (Refrigerant): This process occurs at the compressor unit (Block)
The refrigerator has a compressor unit (number 4 in the illustration) used to compress the refrigerant to high pressure and high temperature, at which point the refrigerant is in a gaseous state.
Step 2: Condensation at the condenser coil (1):
After passing through the compressor, the refrigerant is pushed to the condenser coil (position number 1 in the diagram). Here, the refrigerant at high pressure and temperature is cooled by air and condensed into a liquid with high pressure and low temperature. This is also where the heat dissipation process occurs. Therefore, when you touch the side of the refrigerator where the condenser coil is located, you will feel it is hot.
Step 3: Expansion (2):
Next, the liquid refrigerant at high pressure passes through the expansion device (Position number 3) (Throttle valve). Under the action of the throttle valve, the refrigerant changes from high pressure and low temperature to low pressure and low temperature.
Step 4: Vaporization at the evaporator coil (3):
Here, the refrigerant absorbs heat from the air inside the refrigerator to vaporize. During the vaporization process, the refrigerant will absorb the heat of the air inside the refrigerator and cool the environment inside the refrigerator. After vaporization, the refrigerant (gas) will return to the compressor to continue a new cycle.
The above is the basic operating principle of the refrigerator. Depending on the type and brand of air conditioning unit, this operating process may be arranged differently or supplemented with additional technologies to enhance the features of the device.
