One important factor to remember about refrigeration is that they do not “make cold”, instead, they cycle refrigerant through an evaporator which DRAWS heat away from the contents inside the refrigerator.

And because hot and cold are relative to conditions, we need to understand the core principles of what is hot and what is cold.

To understand this,  think about this for a second first.

If you had to place a cold fridge, at say 4°C in the middle of a Siberian village where temperatures can reach a whopping -18°C, the temperature of the fridge would be relatively warm in comparison to the conditions.

Therefore it’s easier to understand that no matter how cold a fridge is, it’s still referred to as heat.

Let me explain this further. 

If you place a warm cold drink which is at room temperature inside a fridge, it will get cold because it will lose its heat through thermal radiation.

The only way it can do this is because heat moves to cold, therefore the heat given off by the cold drink is drawn to the evaporator which is the cold part, therefore dissipating the heat and lowering the temperature of the cold drink.

This accumulated heat drawn to the evaporator is then absorbed by the passing refrigerant and then discharged as it passes through the system.

It’s during this process that the refrigerant moves through the system and alters states in order to produce a “cold” effect.

To understand this process in a little more detail, refer to the diagram below.

Detailed explanation

Although fridges and freezers may seem simple, there is in fact a tremendous amount of science happening in the background for a fridge to get cold. However, the principles are important to know which can be applied in the field as to how the refrigerant cycles through the system, how changes state, how it draws heat and how it expells this heat.

In order for a fridge to work, there are 7 primary components needed.

	#1: Refrigerant which is commonly known as “gas”. In refrigeration terms, it is refrigerant. It’s the medium which draws heat away from the evaporator and keeps the refrigerator and contents cool.
	#2: Compressor. This unit compresses the refrigerant and ejects it through the system at high pressure to enable heating and cooling cycles.
	#3: Condenser. This cools the refrigerant as it passes in order to stabilize the gaseous state in order to prepare it for cooling when it passes through the capillary tube/TXV.
	#4: Filter drier. Removes moisture and traps debris before it moves into the metering device. This part is incredibly crucial, which ensures that no blockages form in the refrigeration cycles.
	#5: Heat Exchange. This helps cool the discharge line (High-pressure side) further to enable efficient cooling. This occurs through conductance by wrapping the capillary tube around the suction pipe. If a TXV valve is used, the two pipes are tied together with wire or cable ties, and wrapped in foam/rubber insulation. *** Important to remember: On air conditioning units, a heat exchanger is not needed during installation! ***
	#6: A metering device which is either a capillary tube or a TXV. These devices alter the pressure of the refrigerant causing a change in the refrigerant state.
	#7: The Evaporator, where all the magic occurs. This can be a little complicated to understand at first, however, refrigerators do not make cold, instead, they draw heat out of the refrigerator and products which results in cooling.