25-06-2013, 11:59 AM
How does basic refrigeration cycle work?
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The basic refrigeration cycle for beginners
If you are interested in learning how a refrigeration system works, it is helpful to understand from the Ph (Pressure
Enthalpy) chart perspective. It makes our life much easier.
This is how the refrigeration cycle diagram looks
Yeah, it seems complicated at first, but it will be easier to understand once I have explained the refrigeration cycle
diagram section by section. It important to understand the basic refrigeration cycle, to comprehend what is going
on within the air conditioner units, we cannot see it.
The refrigeration cycle tells us if there is air in the central air conditioner units, what to repair after troubleshooting
the refrigeration system, if there is enough air conditioner freon, or if the ac filter is dirty.
You could know the entire thing by knowing the pressure and temperature of the evaporator, condenser, and
compressor.
Once you have found the pressure and temperature, you plot in the Ph charts to determine what and where subcooled
and superheat take place in the Ph charts.
Air conditioning theory
There are two laws that are significant to understand the basic refrigeration cycle and air conditioning.
Thermodynamics’ first law explains that energy cannot be neither created nor destroyed, but can be changed from
one form to another.
Thermodynamics second law can help us better understand how the basic refrigeration cycle works. Once of these
laws state that heat always flows from a material at a high temperature to a material at a low temperature.
As I have mentioned in the residential air conditioners section, air conditioning (the refrigeration cycle) is a process
that simply removes heat from an area that is not wanted and transfers that heat to an area that makes no
difference. The air conditioner itself does not create heat, it just transfers heat.
For heat to transfer, there has to be a temperature and pressure difference. In the refrigeration process there are
two sections which produce a pressure difference: a high-pressure, high temperature section (condenser) and a
low-pressure, low temperature section (evaporator).
The refrigeration system removes heat from an area that is low-pressure, low temperature (evaporator) into an
area of high-pressure, high temperature (condenser).
For example, if cold refrigerant (40°F) flows through the evaporator and the air surrounding evaporator is 75°F,
the cold 40°F will absorb the heat from the 75°F space. By absorbing the heat from the warm space, it also cools
the space. It then transfers that heats to condenser (high side) through compressor.
A hot refrigerant from the compressor flows to a cooler location the condenser medium (air surround condenser)
for example, the refrigerant will give up the hot vapor heat it absorbs from the indoor evaporator and becomes cool
again and turns back to liquid.
Basic refrigeration cycle principles:
1. As refrigerant in the latent state or as vapor refrigerant in the process of changed state to liquid,
this is the phase where it absorbs or rejects large quantities of heat. The quantities of heat
absorbed or rejected can be managed by controlling the pressure and temperature of the
refrigerant.
2. The boiling point of closed-system liquid can be controlled by changing the vapor pressure above
it.
3. Gauge pressure is used to determine the pressure inside the closed refrigeration cycle system.
It’s expressed in pounds per square inch gauge (psig).
4. Heat flows from a material at a higher temperature to a material at low temperature.
5. Heat energy is not created but converted and transferred.