How Do Our
Fridges Work?
The LG Ultra Large Refrigerator (Model LSXS26366S) is a combination fridge and freezer that is used to decrease the internal temperature of the unit and allows you to preserve any food placed inside, Coming in silver or black, this is a stainless-steel rectangular unit that has two doors, a control panel, and the Ice and Water Dispenser on the front.
​
​
​
​
Generally, a fridge is a closed system that consists of:
-
A compressor
-
Condenser coils
-
Evaporator coils
-
Refrigerator fluid
​
Here we will be going in depth on how the LG Ultra Large uses these components to cool it's interior.
Starting with the compressor, found sitting behind the bottom panel at the back of the refrigerator, that acts as the starting point of the refrigeration process. The compressor is a black, hardened/stainless steel chamber. This is to safely contain the high temperatures and pressures that it must withstand. Inside the chamber is a piston that expands and contracts the size of the chamber that is controlled by a simple motor. The entrance and exit of the chamber have valves that only allows the vapor to move in one direction and prevent leakage or reflux in the system. First, entrance valve opens and the piston moves down and causes the volume of the chamber to increase. This creates a low-pressure zone that pulls the vaporized refrigerator fluid (R600a also known as isobutane) into the chamber. The entrance then closes and the piston moves up, forcing the gas out the other side, increasing the pressure and heat in the chamber and system. This happens many times a second, allowing a large amount of pressure to build in the system. When the hot, pressurized vapor gets pushed out of the chamber, it flows towards the condenser coils.
​
​
* This picture depicts freon as the coolant/refrigerant. This is mostly found in older refrigerators. Freon was later abandoned due to effects on the Ozone layer in favor of R600a.
​
In the condenser coils, that sit outside the refrigerated area next to the compressor, the pressurized vapors are turned from gas to liquid. The condenser is a small, simple container with coiled tubes and a cooling fan. The hot vapors run through said coiled copper tubes that have aluminum fins attached. This design allows the tubes to have the most surface area for the air to hit and cool. The fan pushes air over the coils, cooling the vapors within, and pushes hot air out of the back air vents on the fridge. The low temperature and high pressure allow the vapors to condense and go from gas to liquid. This cold, pressurized liquid refrigerant is stored or used immediately in the evaporator coils.
The evaporator coils, that sit inside the back of the refrigerated area, is where the actual cooling occurs. The cold, liquid refrigerant travels through an expansion valve (a cone-shaped pipe that decreases the pressure and increases the flow of the liquid) and then through coils that are very similar to the condenser coils. As heat passively travels from hot to cold, the liquid refrigerant naturally absorbs the heat inside the refrigerator. The long, coiled tubes with aluminum fins attached to them allow them to have the most surface area to absorb as much of heat as possible from inside the refrigerator. This heat will evaporate the refrigerant and this vapor travels back the compressor.
The ice maker, found behind the freezer door, takes advantage of this cold environment. Made mostly of white plastic, the ice maker is shaped like a rectangular ice tray. This ice tray is connected to a water line that fills the tray when it is empty. The water in the tray cools and eventually freezes when it reaches 0°C (32°F). When the tray detects that it has frozen, the bottom of the tray rotates and pushes the ice into a bucket where it is ready to be crushed by auger shaped gears or dispensed whole.
This system creates a closed loop that recycles the refrigerator coolant indefinitely. As long as the compressor can run, the refrigerator can move the coolant through the coils to draw heat from inside the refrigerator. This allows the fridge to cool the interior to make ice and preserve any food you put inside.
