Week 1 Activity

Choosing household-appliances, the chemical product we have selected is the refrigerator. The refrigerator is an essential household appliance, as it helps to preserve our food at low temperatures and keep food fresh.


The temperature inside the refrigerator must be maintained at a low temperature to slow down the bacterial growth in our food. A refrigerator does this by transferring heat from its interior to the exterior.


The components of a refrigerator consist of an evaporator, compressor, condenser, throttle valve, capillary tube and thermostat.


A refrigerator works based on the vapour-compression cycle, also known as the refrigeration cycle.

  1. Inside the refrigerator, the liquid refrigerant enters the evaporator, evaporating completely at a constant pressure. Heat is absorbed from the surrounding region to be refrigerated. At the same time, the capillary tube reduced the pressure on the refrigerant, allowing it to evaporate at a lower temperature.

  2. The gaseous refrigerant leaves the evaporator and is compressed to a relatively high pressure and temperature by the compressor.

  3. The gaseous refrigerant passes through the condenser, where the refrigerant condenses into a liquid. It is cooled by the ambient air, and heat is released from the refrigerant to the surroundings. This is why the back of the refrigerator feels warm when you put your hand on it.

  4. The refrigerant enters the throttle valve and expands, and exits as a liquid-vapour mixture. It is circulated back to the evaporator for further evaporating, and the cycle starts all over again.

  5. The thermostat is used to control the temperature inside the refrigerator. When it senses that the temperature inside the refrigerator is cool enough, it switches off the compressor and the vapour-compression cycle stops. When it senses that the temperature inside the refrigerator is too high, it switches on the compressor again to resume the cooling process.

Figure 1. Vapour-Compression Cycle (ResearchGate)

References

Danfoss.com. n.d. How does a refrigerator work? | How the fridge works | Danfoss. [online] Available at: <https://www.danfoss.com/en-sg/about-danfoss/our-businesses/cooling/the-fridge-how-it-works/#:~:text=Refrigerators%20work%20by%20causing%20the,and%20produces%20the%20desired%20effect.&text=When%20you%20release%20the%20contents,a%20liquid%20to%20a%20gas> [Accessed 27 April 2021].


Diagram of the Basic Refrigeration Cycle, digital photograph, ResearchGate, accessed 27 April 2021, <https://www.researchgate.net/figure/Diagram-of-the-Basic-Refrigeration-Cycle13_fig2_324836043>.

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