The evaporator has cool refrigerant running through it while the warmer space air is passing over it. The refrigerant absorbs the heat from passing through the coil and leaves cooler air to enter back into the space.
The evaporator works the opposite of the condenser, here refrigerant liquid is converted to gas, absorbing heat from the air in the compartment.
As perspiration evaporates it absorbs heat to cool your body. The principle underlying evaporative cooling is the fact that water must have heat applied to it to change from a liquid to a vapor. When evaporation occurs, this heat is taken from the water that remains in the liquid state, resulting in a cooler liquid.
As refrigerant travels through the evaporator, it absorbs heat from the air. As it absorbs heat, it vaporizes. If the system operates according to design, the refrigerant will be 100% vapor as it nears the exit of the evaporator. Before leaving the evaporator, the vapor continues absorbing heat, becoming superheated.
Hot, pressurized refrigerant gas arrives from the compressor into the condenser, which is designed to reject heat by lowering or returning the temperature of the refrigerant to its condensing temperature. As it rejects heat, the condenser converts the vapor to a sub-cooled liquid.
The evaporator gathers/absorbs heat from the refrigerated space into a “bucket.” The “bucket” is low-pressure, and it changes state (latent heat transfer) as it absorbs heat. Then the evaporator moves the low-pressure, heat-filled “bucket” to the compressor.
Condenser.
In the condenser unit, the refrigerant is compressed, causing it to release the heat it absorbed in the evaporator coil. Release of Heat: As the refrigerant releases heat, it condenses back into a liquid state. This heat is expelled into the outdoor air by the condenser coil and a fan.
The evaporator is the part of a refrigeration system that absorbs heat from the air or other substance to be cooled. The heat then passes through coils into a compressor, where it is compressed and cooled even further.
Since refrigerant comes out of the evaporator as a superheated vapor, it will enter the compressor as a superheated vapor. The compressor's job is to increase the pressure of the refrigerant. Recall that as pressure increases, temperature increases. This is exactly what the compressor does.
In the refrigeration cycle, the refrigerant absorbs the most heat in the evaporator stage. The evaporator is where the liquid refrigerant absorbs heat from the surrounding air or objects, causing it to evaporate and turn into a gas.
The process of freezing is a constant temperature process and the heat is given off when freezing occurs. In fact in freezers, the heat is extracted from the water or foodstuff so that freezing can take place. The heat must be extracted for the phase transformation of a liquid into a solid (ice).
Evaporation occurs when a liquid changes to a gas. During evaporation, molecules gain enough thermal energy to escape from the liquid surface into the air as water vapor.
Refrigerant can shift easily between liquid and gas states, which makes it ideal for ACs since it doesn't take significant amounts of energy to cause the phase shift. Refrigerant starts inside the compressor, where the reduction of volume turns it into a high pressure gas about 150°F.
Evaporation is an endothermic process, since heat is absorbed during evaporation.
The evaporator functions by allowing the refrigerant to evaporate and expand in a controlled environment. As the liquid refrigerant enters the evaporator, it encounters low pressure, which causes it to vaporize and absorb heat from the surrounding air or medium that needs cooling.
Upon entering the evaporator, the liquid refrigerant's temperature is between 40° and 50°F; and without changing its temperature; it absorbs heat as it changes state from a liquid to a vapor. The heat comes from the warm, moist room air blown across the evaporator coil.
The condenser is a heat rejection device. The refrigerant system picks up heat in the evaporator and also from the heat of compression (from the compressor itself), and the condenser rejects or rids the heat.
Because refrigerants have lower boiling points, they 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. For example, a hot summer day would be around 90°F. A typical refrigerant, R-134a, has a boiling point of -15.34°F!
Evaporator Coil Function
Also called a direct expansion (DX) coil or refrigerant coil, the evaporator is what provides the 'refrigeration effect' in most heating and cooling systems, absorbing thermal energy from the space being conditioned and routing it elsewhere.
When the refrigerant reaches its saturation temperature, the latent heat is rejected and a liquid film forms on the heat transfer surface. The condensing process represents the majority (70-80%) of the total heat of rejection (b-c).
In the evaporator, refrigerant absorbs heat from the indoor air to change state from liquid to vapor. This means that when the refrigerant leaves the evaporator, it is fully in vapor state.
An evaporator, through which the low-pressure, low-temperature refrigerant absorbs heat from a heat sink (e.g., a freezer compartment or a space to be refrigerated) and changes from a two-phase mixture to a saturated or superheated vapour.
The refrigerant at the entry to the evaporator is low pressure and low temperature liquid. The pressure is reduced in the capillary tube thus also decreasing the temperature. This low pressure, low temperature liquid is converted to low pressure vapours after absorbing heat from the evaporator.
The heat of compression raises the temperature of the refrigerant vapor causing it to be a high pressure superheated vapor. As this refrigerant moves into the condenser (2), the condenser rejects the heat in the refrigerant, causing it to change state and condense into a high pressure, high temp liquid.