The compressor is absolutely vital to the functioning of a refrigerator. To understand the purpose of the compressor we must understand how a refrigerator works.
How refrigeration Compressor works
The refrigeration circuit is a closed loop consisting of the compressor, the condenser, the capillary tube and the evaporator. Inside this system is the gas refrigerant. Most commonly the refrigerant is Isobutane, often referred to as R-600a. A refrigeration compressor uses the transfer of energy when the refrigerant changes state between gas and liquid to cool the air within the fridge
. This is a similar process to that which the human body uses to cool down, by sweating.
The compressor's role in this cycle is to take the gas that comes from the evaporator and increase pressure in the refrigerant gas. This is done by using an electric motor to move a piston which draws the gas from the evaporator into the "block". As the piston is pushed back into the block, the gas is forced into the discharge cylinders and from there into the discharge tube. The act of forcing the gas into the smaller area of the discharge tube increases its pressure and temperature. The discharge tube feeds the gas to the discharge connector on the exterior of the compressor, which is connected to the condenser.
The condenser (usually located on the back of the refrigerator) allows heat to be expelled from the gas refrigerant, cooling and transforming it into a liquid. It then passes through the capillary tubes to the evaporator (inside the refrigerator). The evaporator allows the cooled liquid refrigerant to pass through the refrigerator and absorb heat. As the liquid refrigerant absorbs heat it evaporates, transforming back into a gas and losing pressure. This process continues until the desired temperature is attained, at which point the thermostat turns off the compressor and stops the cycle.
Over the years a number of enhancements and developments have improved the modern compressor unit in refrigerators. A muffler is fitted to the intake from the evaporator which reduces the 'sucking' noise of the piston. The discharge tube inside is formed in a curved concertina shape to allow it to flex with the movement of the compressor. This reduces noise and prevents it breaking. The compressor motor mounts are sprung to reduce noise and vibration being transferred to the refrigerator. Many compressors now have two discharge cylinders connecting to a single discharge tube to improve efficiency.