TRG-TRC012-EN 11
period one
Components
notes

Expansion Device

An expansion device is used to maintain the pressure difference between the
high-pressure (condenser) and low-pressure (evaporator) sides of the system,
as established by the compressor. This pressure difference allows the
evaporator temperature to be low enough to absorb heat from the water being
cooled, while also allowing the refrigerant to be at a high enough temperature
in the condenser to reject heat to air or water at normally available
temperatures. High-pressure liquid refrigerant flows through the expansion
device, causing a large pressure drop that reduces the refrigerant pressure to
that of the evaporator. This pressure reduction causes a small portion of the
liquid to boil off, or flash, cooling the remaining refrigerant to the desired
evaporator temperature.
In this chiller, the expansion device used is an electronic expansion valve. In
addition to maintaining the high- and low-side pressure difference, the
electronic expansion valve controls the quantity of liquid refrigerant entering
the evaporator to ensure that it will be completely vaporized within the
evaporator.
expansion device…
Electronic Expansion Valve
Figure 19