Pressure
Pressure is the force
per unit area. It is expressed in pounds per square inch (psi). Operation of a
refrigeration system depends mainly on pressure differences in the system.
Substances always push on the supporting or containing them.
The pressure exerted on the refrigerant in a refrigeration system determines both the evaporating and condensing temperatures of refrigerant. When the pressure over the liquid is changed the boiling temperature also changes. If the pressure is increased, the boiling temperature increases. If the pressure is decreased, the boiling temperature decreases. The compression refrigeration system is based on this phenomenon.
A block of ice (solid)
exerts a pressure on its support. If the support were removed, the block would
fall to another support level.
Block of ice (solid)
A
mass exerts downward force only
A liquid exerts a
pressure on the sides and bottom of its container.
Water (liquid) water
Exerts
pressure on container both downward and horizontally
A gas exerts a
pressure on all surfaces of its container
Vapor (gas)
Vapor or
gas in rubber balloon exerts pressure uniformly in all directions.
The pressure exerted on the refrigerant in a refrigeration system determines both the evaporating and condensing temperatures of refrigerant. When the pressure over the liquid is changed the boiling temperature also changes. If the pressure is increased, the boiling temperature increases. If the pressure is decreased, the boiling temperature decreases. The compression refrigeration system is based on this phenomenon.
Source : Panasonic
