• SkillCat Team

Refrigeration Cycle Overview

Updated: 3 days ago

EPA 608 Core Chapter 12 (Take full course for free)


In this module, we will go over the basic concepts behind the refrigeration cycle. We will discuss how the refrigeration cycle powers your air conditioning and refrigerator. Skip to quiz!


1. How Does the Refrigeration Cycle Work?


In your daily life, you are likely surrounded by comforts made possible by the refrigeration cycle — especially during the hot summer months. The refrigeration cycle is what powers your air conditioning unit and, on a smaller scale, your refrigerator.


As mentioned in the video, air conditioning works by absorbing heat from your indoor air and ejecting it outdoors.


It does this by passing a refrigerant with a low boiling point through a series of coils that come in contact with warm indoor air. Recall that a boiling point is the temperature at which liquid turns to vapor.


In the refrigeration cycle, we use refrigerants with low boiling points. This means that the refrigerant will boil at a lower temperature than your indoor temperature on a hot day. This is so that your indoor air is hot enough to make the refrigerant boil.


The most commonly used refrigeration system is called the direct expansion vapor compression system. For example, this type of system is found in both your air conditioning as well as your refrigerator.


Direct expansion systems are systems where the cooling effect comes from the expansion of a liquid to a vapor. If we think about water vaporizing to steam, the steam rises up and fills the air. This is the “expansion” behavior of vapors.



2. Vaporization


As the refrigerant boils, it changes state from liquid to vapor. As mentioned in the review, this process is also called vaporization, as the refrigerant is changing from liquid to vapor.


Recall that during vaporization, or boiling, you need to add continuous heat until all liquid has changed state to vapor.


Think about boiling a pot of water. You apply heat to it by turning on the stove, which increases the temperature of the water. Once the water reaches its boiling point, it starts to bubble and turn into steam, which leaves the pot and dissipates into the air.

If you keep the stove on, you are continuously applying heat to water that is already at its boiling temperature. More and more water molecules will become steam, which is also known as water vapor.


If the stove is left on, the water in the pot will decrease until all the water eventually turns to vapor. You’ve probably seen this if you’ve accidentally left the stove on too long. Either the pot has completely dried up or there’s much less water than before. This is because water has changed state into vapor.


If you turn off the stove after the water starts to boil, the water will stop boiling and remain in the pot. This demonstrates that you need to continuously apply heat in order for all of the water to become vapor.


In the refrigeration cycle, instead of water, you have refrigerant boiling. And instead of a stove flame, it is the hot indoor air that is providing heat for refrigerant to completely boil. This process is what draws heat away from your indoor air and provides cooling.


To reiterate, it is the boiling or vaporization of refrigerant that provides cooling in a refrigeration system.


As the refrigerant moves through the refrigeration cycle, it effectively transfers heat from inside the house to outside the house.


3. Conclusion


The refrigeration cycle is what powers cooling in your air conditioning system or refrigerator.

Next, we’ll go into more detail about the components of the refrigeration cycle and what happens in each component.


In the refrigeration cycle, refrigerant absorbs heat from your indoor air by using that heat to boil, changing state from liquid to vapor. We choose refrigerants with a low boiling point in order for this to happen.


Question #1: Your air conditioning works by adding cold air into your house.

  1. True

  2. False

Scroll down for the answer...












False! This is false. Your air conditioning works by absorbing heat from your indoor air, not by adding cold air.


Question #2: Refrigerant absorbs heat from your indoor air in order to (Select all that apply)

  1. Change state from vapor to liquid

  2. Change state from liquid to vapor

  3. Make your house cooler

  4. Evaporate into the air

Scroll down for the answer...











Refrigerant absorbs heat from your indoor air in order to change state from vapor to liquid and make your house cooler.

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