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The vital role of thermostatic control in refrigeration explained.

A fridge thermostat is a device that controls the temperature inside a refrigerator or freezer by regulating the operation of the refrigerant compressor. Here's an explanation of how a fridge thermostat functions:

  1. Sensing: The fridge thermostat usually comprises of temperature sensor (NTC), or a mechanical bimetal type, which detects the

  1. evaporator temperature inside the refrigerator compartment. The sensor/thermostat is usually located near the evaporator coil, where saturation takes place.

  2. Set Point Adjustment: The thermostat allows users to set their desired temperature using a control knob or buttons. When the user selects a specific temperature, they are adjusting the set point of the thermostat.

  3. Comparison: The temperature sensor continuously measures the actual temperature inside the fridge compartment and compares it to the set point. If the temperature is higher than the set point, it triggers the compressor to start, if it's lower, it shuts off the compressor.

  4. Relay or Switch: The NTC sensor typically uses a relay or a switch to control the power supply to the refrigerator's compressor. When the temperature rises above the set point, the NTC sends an electrical signal to activate the compressor. This initiates the cooling process by compressing the refrigerant, which releases heat outside the fridge and cools the interior.

  5. Cycling: Once the cooling system is activated, the compressor runs until the temperature inside the fridge drops below the set point. At this point, the thermostat interrupts the power supply to the compressor, causing it to stop. This cycle repeats as necessary to maintain the desired temperature.

  6. Defrosting: In some refrigerators, the thermostat also controls the defrosting cycle. After a certain period of time or when frost buildup is detected, the thermostat activates a defrost heater or initiates a defrosting process to remove ice or frost from the evaporator coils. This ensures efficient cooling by preventing excessive frost accumulation.

By continuously monitoring the temperature and activating the compressor as required, the fridge thermostat helps maintain a consistent and controlled environment inside the refrigerator to keep food fresh and safe for consumption, furthermore, optimises the energy efficiency of the appliance.


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