Part 2 Flashcards
Revolvers tank should not be filled beyond
80%
High pressure terms
High Side,” “Head Pressure” and “Discharge
Pressure”
Low pressure terms
Suction Temperature,” “Evaporator Temperature”
and “Saturated Suction Temperature”
Low side gauge reads
Reads suction pressure
• Reads suction temperature
• Reads vacuum
High side gauge
Reads condensing pressure
• Reads condensing temperatur
Saturated” refrigerant:
A mixture of liquid and vapor at the same time
– It has a pressure / temperature relationship
If you know the suction pressure
You can find the refrigerant’s evaporating temperatur
If you know the head pressure,
You can find the refrigerant’s condensing temperatur
Temp
Intensity of heat in degrees
Quantity
Amount of heat in BTU
Sensible Heat
Change in temp
Latent Heat
Change in state
Water raises…
Raises I lb per 1F
Ice raises
1 lb per 2F, specific heat of 0.5
144 Btu will change 1 lb of 32°ice
To 32* water
Heat of fusion
Is required to change ice to water
Sensible heat is measured with
Thermometer
1 Btu raises 1 lb water 1°F
Getting vapor back to a liquid
Latent heat must be removed from the vapor
The outdoor air cools hot refrigerant Vapor
The heat is absorbed by the cooler air
If vapor is cooled to it’s condensing temperature
Vapor condenses to a liquid
Below it’s boiling point?
Subcooled-liquid only
Boiling point
Saturated, part liquid part vapor
Above boiling point
Superheat - Vapor only
Matter
Solid gas and liquid ,
Space and has mass
Blocks of ice exerts force
Downwards
Liquid exerts force
Outward and down
Gases push…
In all directions
Weight
Is the force that the matter of an object exerts on a surface
Density
Mass to volume relationship
Boules Law
Relates pressure and volume
Charles law
Pressure and temp
Law of perfect gas
Pressure volume and temp
Dalton’s law
Relates pressure of gases in a mixture
Air expands when
Heated
Dalton’s law of preffect pressure
The perfect pressure is the sumof inidual pressure of gas
Absolute pressure in a cylinder double…
When the volume reduces by half
High temperature: air conditioning
Comfort
Medium temp;
fresh food preservation
Low temp
Frozen foods
Cooler air falls out because it’s heavier replaced by
Hot air
Refrigeration
Process of replacing heat from a place where is objectionable to where it makes little or no difference
Heat is pumped from a cold box
To a warm room
Water boils at 250°F if pressure is increased
If increases to 15psig
Water boils at 40°F if pressure is reduced to
0.248HG
Saturation temperature:
point at which the addition
or removal of heat will result in a change of state
Refrigerants
Refrigerants are substances that boil at low
pressures and temperatures and condense at high
pressures/temperatures
Evaporator
Absorbs heat to be cooled
Compressor
creates pressure difference needed to
facilitate refrigerant flow through the system
Condenser
Rejects systems heat
