Basic Refrigeration
Basic Refrigeration
Terminology
Heat Form Of Energy
Cold Absence Of Heat
Heat Types Sensible And Latent
BTU Unit Of Heat
Ton Cooling Capacity
Saturation Boiling Point (Change State)
Superheat Vapor Temperature Above Saturation
Subcooling Liquid Temperature Below Saturation
Refrigerant Cooling Medium
Enthalpy Heat Content In 1 lb Of A Substance / Refrigerant
- Based On Temperature And Pressure
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Basic Refrigeration
Types Of Heat
SENSIBLE HEAT
LATENT HEAT
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Basic Refrigeration
Types Of Heat
SENSIBLE HEAT
Energy (Heat) added or removed which causes a
change in temperature but not state
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Basic Refrigeration
Types Of Heat
LATENT HEAT
Energy (Heat) added or removed which causes a
change in state but not in temperature
For example:
As ice in a container melts, heat
energy is being absorbed from the
ambient. The temperature of the ice
and water mixture, however, will not
change as long as ice is present.
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Basic Refrigeration
Types Of Heat
BTU : British Thermal Unit
The amount of heat required raise
the temperature of one pound of
water one degree Fahrenheit
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Basic Refrigeration
Types Of Heat – Latent Heat Of Fusion
A latent change that takes place as a solid becomes liquid or a
liquid returns to its solid form is called the latent heat of fusion.
It requires 144 BTUs of energy to
change 1 lb of ice into 1 lb of water
and yet no temperature change
Temperature
takes place during this process.
144
BTUs
32 °F
BTUs
BTUs
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Basic Refrigeration
Types Of Heat – Sensible Heat
A Sensible Change Is A Change In Temperature Only
212 °F Once all of the ice has melted, the
temperature of the water will begin to rise.
It takes 180 BTUs of energy to raise the
Temperature
temperature of 1 lb of water from 32 °F to
212 °F.
180
BTUs
32 °F
BTUs
BTUs
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Basic Refrigeration
Types Of Heat – Latent Heat Of Vaporization
The change that takes place as a liquid becomes vapor or a vapor
returns to its liquid form is called the latent heat of vaporization.
It requires
970 BTUs of
energy to
change 1 lb
of water into
1 lb of
Temperature
saturated
steam,
yet no
temperature
change takes
970 place during
BTUs this process.
BTUs
BTUs
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Basic Refrigeration
Refrigerant Phases – Subcooled, Saturated & Superheated
R ED
PO AT
VA HE
R
PE
Latent change
SU
LIQUID D
O LE
Saturated Liquid
Saturated Vapor
Temperature
SUBCO
BTUs
BTUs
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Basic Refrigeration
Capacity - Ton Of Refrigeration
288,000 btu are required to melt
1 Ton of ICE over a 24 hr period.
288,000btu / 24hrs = 12,000btu/hr
therefore
1 TON of Refrigeration = 12,000
btu/hr
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Basic Refrigeration
Pressure / Temperature Relationship
Temperature Lo Hi
Pressure Lo Hi
NOTE:
The Relationship Between Pressure & Temperature
Only Exists When Liquid And Vapor Are Present
Together.
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Basic Refrigeration
Pressure / Temperature Graph
400
350
300 (R-410A)
250
Pressure
PSIG
200
(R-404A)
150
100
(R-22)
50
0
0 10 20 30 40 50 60 70 80 90 100 110
Temperature F
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Basic Refrigeration
Points To Remember
Heat (BTU) Moves From Higher To Lower Temperature
Refrigerant Moves From Higher To Lower Pressure
(ΔP)
Liquid Refrigerant Absorbs Heat In Evaporator
(Changing State From Liquid To Vapor)
Vapor Refrigerant Gives Off Heat In Condenser
(Changing State From Vapor to Liquid)
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1 pound of + 140 BTU = 1 pound of
Water 72˚ (Sensible Heat) Water 212˚
1 pound of + 970 BTU = 1 pound of
Water 212˚ (Latent Heat) Steam 212˚
1 pound of + 8 BTU = 1 pound of
Steam 212˚ (Sensible Heat) Steam 220˚
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Basic Refrigeration
System Components – “Must Haves”
Condenser Thermostatic
Expansion Valve
Evaporator
Compressor
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Basic Refrigeration
Saturated Refrigerant
Liquid And Vapor In Contact Saturated Refrigeration
With Each Other In
Example: Conditions, R-22 - 289 PSIG
Equilibrium
128°F Temperature
Pressure And Temperature
Tied Together
P/T Chart Is Applicable
P-T Chart at 289 PSIG R-22 = 128°F
Line Temperature = 128°F
Refrigerant is Saturated
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Basic Refrigeration
Saturated Refrigerant
Condenser Thermostatic
Expansion Valve
Evaporator
Compressor
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Basic Refrigeration
Superheated Refrigerant
Heat Added To Refrigerant Superheated
Vapor Above Its Saturation Example: Conditions, R-22 - 75.0 PSIG
Temperature Suction Line - 54°F
Line Temperature = 54°F
P-T Chart at 75.0 PSIG = 44°F
P/T Charts Do Not Apply - 10°F
Coil Operating at 10°F Superheat
Temperature Rises Without A
Rise In Pressure
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Basic Refrigeration
Superheated Refrigerant
Condenser Thermostatic
Expansion Valve
Evaporator
Discharge Line
Suction Line
Compressor
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Basic Refrigeration
Subcooled Refrigerant
Heat Removed From The Subcooling
Example: Conditions, R-22 - 280 PSIG
Liquid Refrigerant Below Its
120°F Line Temperature
Saturation Temperature
P/T Charts Do Not Apply-
Temperature Drops Without
A Drop In Pressure
P-T Chart at 280 PSIG =
125°F
Line Temperature = 120°F
5°F
Refrigerant Sub-cooled at 5°F
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Basic Refrigeration
Subcooled Refrigerant
Liquid Line
Condenser
Thermostatic
Expansion Valve
Evaporator
Compressor
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Basic Refrigeration
Basic System & Three Phases Of Refrigerant
Liquid Line
Condenser Thermostatic
Expansion Valve
Evaporator
Discharge Line
Suction Line
Compressor
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Basic Refrigeration
Typical Air Conditioning System - Residential
“OUTSIDE” Liquid Line
Thermostatic
Expansion Valve
Condenser
Evaporator
Discharge Line
Suction Line
Compressor
“INSIDE”
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