All About The Refrigeration Cycle

You may not realize it, but your refrigerator runs on multiple HVAC devices that all work to keep your fridge cold. Knowing what each component is and how it works is important so you can identify problems if and when they occur.

For commercial refrigerators, the refrigeration system makes up almost half of the total cost of the entire unit. When a fridge stops working, many people elect to just buy a whole new refrigerator. However, you can often save hundreds of dollars by just repairing or replacing the broken component.

The refrigeration unit consists of four main components: the evaporator, the compressor, the condenser, and the expansion device. Essentially, refrigeration operates on the continuous transfer of heat through these components. Rather than creating cold air, the components use a thermodynamic cycle to transfer heat out of the fridge.

This cycle works by repeatedly turning refrigerant from a liquid into a gas and back again. Refrigerant is a specific type of working fluid that runs between the refrigeration components in a continuous loop. It can absorb heat and leave cool air behind when piped through an evaporator or condenser.

The repetitive heating and cooling process consists of four steps. They are the same steps and components that AC units use to transfer heat out of your home. The cycle repeats at a constant pace to keep cold air continuously running to your fridge.

The first step in the refrigeration cycle is compression. The refrigerator compressor is the engine of your refrigeration system and is responsible for pumping refrigerant through the system. Out of all the components, the compressor consumes the most power, so making sure it works properly is vital.

Here, refrigerant starts as a vapor with a low pressure and temperature. The compressor then heats and compresses the vapor until it is hot and highly pressurized. Once the refrigerant passes through the compressor, it enters the refrigerator condenser.

The condenser is a type of heat exchanger that sits after the compressor in the refrigeration cycle. Hot, gaseous refrigerant runs through a series of coils in the condensing unit. The cooler air surrounding the coils draws the heat out and allows the refrigerant to cool down. The condenser coils work to transfer heat from the refrigerant into the air.

The drop in temperature and increase in pressure condenses the hot, gaseous refrigerant into a liquid. After that, the high-pressure liquid approaches the expansion device.

The expansion device controls the pressure and flow of refrigerant through the system. The sole purpose of the expansion valve is to reduce the pressure of the refrigerant. The pressure drop happens so rapidly that the hot liquid turns into a combination of cold liquid and vapor. This quick phase change is called flashing, and it prepares the refrigerant for the evaporator.

Finally, the refrigerant moves to the evaporator, which is another type of heat exchanger in the refrigeration cycle. The evaporator is responsible for absorbing heat by boiling the refrigerant flowing through it. Low-pressure liquid refrigerant enters the evaporator coils, comes to a boil, and turns back into a cool vapor.

When the refrigerant boils and reverts to a gas, the heat from the air filters out, leaving cool air behind. The unit then pumps that cold air into the fridge, and this continuous process keeps refrigerators consistently cold.

Because there are so many working parts in the refrigeration cycle, there are more places for malfunctions to occur. Keeping each component in top condition is important to the overall wellbeing of your fridge. Most maintenance practices are simple enough that you can do them yourself. Always make sure to turn your fridge off before doing any maintenance work on its parts.

Cleaning evaporator and condenser coils is one of the best things you can do for your refrigerator’s longevity. You will typically find condenser coils on the back or bottom of your fridge, and evaporator coils inside the fridge. Dirt, dust, and pet dander can clog up coils and cause blockages in the release of heat. When coils can’t efficiently release heat, it wears on the whole system and makes each component work harder than they need to.

The condenser fan is also another component that can accumulate dirt and dust. Usually located on the back or bottom of the fridge near the coils, the fan is equally as important to clean. With all the heat release happening in the refrigeration cycle, the condenser fan prevents the components from overheating and damaging the fridge.

You don't need special equipment to clean your refrigerator coils or condenser fan, just a small duster and a vacuum. Coil cleaning brushes designed specifically for refrigerator and AC systems are also available and inexpensive.

Refrigerator and AC maintenance has huge preventative benefits and the power to save you money. By doing a routine cleaning twice a year, you can save $5 to $10 extra a month on your utility bill.