evaporator?
Air conditioner evaporator is a
heat exchange. It takes in low
temperature, low-pressure liquid
refrigerant from the expansion
device and changes it into low-
pressure, low temperature vapor
refrigerant.
Evaporator coil is the
components that add heat to the
air conditioner units.
* Notes: refrigeration is the
process of removing heat from
one area where it is undesirable
to an area where it is not
significant. For this process to
work heat has to flow from one
area (medium) to another.
To make heat flows, one of the
mediums has to be at a higher
temperature. Since, heat always
flows from a high intensity to a
low intensity.
Types of air conditioner
evaporator:
Director-expansion or Air-cooled
Evaporator
1. Flooded evaporators
How does air conditioning
evaporator works?
Air conditioning evaporator
works by absorb heat from the
area (medium) that need to be
cooled. It does that by
maintaining the evaporator coil
at low temperature and pressure
than the surrounding air.
Since, the AC evaporator coil
contains refrigerant that absorbs
heat from the surrounding air,
the refrigerant temperature must
be lower than the air.
The expansion device provides a
pressure reduces between the
high side and the low side of the
system, the saturation
temperature of the refrigerant
entering the air conditioning
evaporator is lower than the
medium to be cooled.
One of the characteristic of a ac
refrigerant is that as the
pressure is reduced the boiling
point is also reduced. Therefore,
as the pressure is reduced
through the expansion device so
is the point at which it will boil
and become a vapor.
As the warm air from the space
passes over the evaporator coil,
it gives up its heat to the lower
temperature liquid/vapor
mixture passing through the
evaporator. As the liquid
refrigerant absorbs this heat it
boils changing from the liquid
state to the vapor state.
The amount of heat the air
conditioner evaporator absorbs
must equal the amount of heat it
lost
For instance, if the air
conditioning evaporator gives
up 100 Btu’s of heat to the
surrounding hot air, then the
refrigerant within the air
conditioning evaporator coil
must gain 100 Btu ’s of heat.
The amount of liquid entering
the evaporator must be enough,
so by the time it reaches the end
of the evaporator. It will be
completely boiled to the vapor
state.
There must be enough air flows
across the AC evaporator coil to
provides heat to the refrigerant
in the evaporator coil. This is just
a safety way to ensure the air
conditioner compressor doesn ’t
have the liquid refrigerant
entering it.
Air conditioning evaporator
picture above tells us what
happen to the evaporator coil.
The air conditioning evaporator
coil absorbs heat into the
refrigerant from the warmer air
passing over the surface of the
evaporator coil. The heat
absorbed causes the liquid
refrigerant to boil, changing it
from a liquid state to a vapor
state.
Types of air conditioning
evaporator coil:
Bare-tube coils
1. Finned-tube coils
2. Flat-plate coils
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