How does the diffuser work in a domestic refrigerator?

In a domestic refrigerator, the diffuser plays a crucial role in the refrigeration cycle. It is a component of the refrigerator's evaporator, responsible for regulating and expanding the high-pressure refrigerant gas (typically R134a or R600a) into a low-pressure gas. Here's how the diffuser works:

1. Refrigerant Flow: During the refrigeration cycle, the high-pressure refrigerant gas coming from the compressor enters the diffuser through an inlet port.

2. Sudden Expansion: The diffuser acts as an expansion device by suddenly expanding the high-pressure refrigerant gas into a larger chamber or section. This sudden expansion causes a significant drop in pressure and a corresponding decrease in the gas temperature.

3. Pressure Equalization: As the refrigerant gas expands within the diffuser, its speed decreases, allowing the pressure to equalize throughout the evaporator. This ensures a uniform distribution of low-pressure refrigerant gas into the evaporator coils or tubes.

4. Flashing and Evaporation: The sudden pressure drop inside the diffuser causes a portion of the high-pressure refrigerant gas to flash into a vapor or mix of liquid and vapor. As the refrigerant absorbs heat from the surroundings (inside the refrigerator), more of the liquid refrigerant evaporates and absorbs additional heat.

5. Heat Exchange: The evaporator (including the diffuser) is located in the fresh-food compartment or freezer section of the refrigerator. The diffuser allows the low-pressure refrigerant gas to interact with the warmer air inside the refrigerator, facilitating efficient heat transfer and cooling.

6. Refrigeration Effect: By absorbing heat from the inside of the refrigerator, the diffuser helps in cooling the air and lowering the overall temperature inside the appliance. The cooled refrigerant gas then travels through the rest of the evaporator, where the cooling process continues before transitioning into the compressor.

7. Control Valve: Some refrigerators may have a control valve or orifice at the diffuser inlet. Adjusting this valve can regulate the flow rate of the refrigerant and hence influence the cooling capacity.

Overall, the diffuser in a domestic refrigerator contributes to reducing the pressure of the refrigerant gas effectively and facilitates efficient heat exchange within the evaporator, resulting in the desired cooling performance and maintaining the desired temperature inside the refrigerator.