Study your flashcards anywhere!

Download the official Cram app for free >

  • Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off
Reading...
Front

How to study your flashcards.

Right/Left arrow keys: Navigate between flashcards.right arrow keyleft arrow key

Up/Down arrow keys: Flip the card between the front and back.down keyup key

H key: Show hint (3rd side).h key

A key: Read text to speech.a key

image

Play button

image

Play button

image

Progress

1/60

Click to flip

60 Cards in this Set

  • Front
  • Back
Heat is made up of what?
Matter
What is matter?
Anything that has weight and occupies space.
What are some types of matter?
Solid, liquid, and gas.
What is a molecule?
The smallest particle of matter that can exist and still retain the properties of matter.
What does temperature measure?
The intensity of heat in degrees F or C.
How is quanity of heat measured?
In Brittish Thermal Units.
What is sesible heat?
Heat added or removed from a substance which CHANGES the temperature, but NOT the physical state.
How is sensible heat measured?
With a thermometer.
What is Latent Heat?
Heat added to or removed from a substance which changes PHYSICAL STATE not Temperature.
How is Latent Heat measured?
Through Brittish Thermal Units.
What is Latent Heat of Vaporization?
Heat that is ADDED to change the STATE of a substance from a LIQUID to a VAPOR.
What is Latent Heat of Condensation?
Heat that is REMOVED to change the STATE of a substance from a VAPOR to a LIQUID.
What is Latent Heat of Fusion?
Heat that is REMOVED from a substance to change the STATE from a LIQUID to a SOLID.
What is Latent Heat of Melting?
Heat that is ADDED to a substance to change the STATE from a SOLID to LIQUID.
What is Superheat?
The sensible heat ADDED to a vapor ABOVE its boiling temperature.
What is subcooling?
Sensible heat REMOVED from a liquid BELOW its condensing temperature.
What is total heat?
Used to determine all heat present in British Thermal Units.
How does heat flow?
Warmer to cooler.
How is radiation transfered?
By direct rays. Like the sun.
How is conduction transfered?
Physical contact
How is convection transfered?
By a medium being circulated:

1. Natural Flow
2. Forced Convection(Fan coil unit)
What is the definition of a British Thermal Unit?
One BTU is the amount of heat required to change the temperature one pound pure water one degree Fahrenheit at atmospheric pressure at sea level. (14.7 PSIA)
What is specific heat value of water?
1/BTU/LB/Degree F
What is the specific heat value of Steam?
.5/BTU/LB/Degree F
What is the specific heat value of ice?
.5/BTU/LB/Degree F
What is the Latent Heat content when calculating from ice to water?

In BTU'S
144 BTU's/LB
What is the Latent Heat content when calculating from water to steam?

In BTU's
970 BTU's/LB
What is absolute pressure at sea level?
14.7 PSIA
What is Latent Heat in refrigeration?
The ability for a refrigerant to absorb or dissipate its latent heat is the fundamental principle of the refrigeration process.
What is heat?
Form of energy
What are three types of heat transfers?
Radiation, convection, and conduction.
What is total heat?
All thermal energy
What is the definition of pressure?
Pressure is force per unit are
What is Boyle's Gas Law?
The Volume of a gas varies inversely as to pressure, as long as the temperature remains constant.
What is Charles Gas Law?
At constant pressure the volume of a confined gas varies directly with temperature and at constant volume, the pressure varies directly with temperature.
What is Pascal's Pressure Law?
Pressure applied upon a confined fluid is transmitted EQUALLY in all directions.
What is Dalton's Partial Pressure Law?
The total pressure of a confined MIXTURE OF GASES is the sun of the pressure of each of the gases in the mixture. The total pressure of the air in a compressed air cylinder is the sum of the oxygen, nitrogen, carbon dioxide gases, and water vapor pressure.
What does a barometer do?
Measures Atmospheric Pressure
What is the effect of heat on pressure and temperature?
Heat will not change the boiling temperature provided the pressure remains constant.
What is the Pressure-Temperature relationship of the same substance?
Substance of a liquid or vapor must be the same.(R-134A liquid and R-134A vapor) The liquid and vapor must be in physical contact and in one container.
What is the compression stage?
Increases pressure and temperature of the refrigerant. Moves refrigerant.
What is the condensation stage?
Dissipates heat
What is the expansion phase?
Meters refrigerant into the evaporator to allow it to absorb its latent heat
What is the evaporator stage?
Absorbs heat
What is the purpose of the compressor?
Raises the pressure and temperature of the refrigerant above the cooling medium.
What is the purpose of the condenser?
Desuperheats, condenses, and subcools
What is the function of the Thermal Expansion Valve?
The TXV meters the flow of liquid refrigerant into the evaporator depending on heat load, and maintains superheat.
What is the purpose of the Evaporator?
Absorbs heat. Refrigerant flashes in the condenser, which removes heat from the product.
Name three laws of heat transrer.
1. Warmer to cooler
2. Greater the temp. difference, the faster it flows
3. Objects in contact will equalize
Which switch controls the starting and stoping of the compressor?
The Low/Suction Pressure Switch
What is the purpose of the Low/Suction Pressure switch?
Starts and stops the compressor automatically at a predetermined setting
What are three safety switches?
1. Low Lube
2. High Discharge Pressure
3. Saltwater Failure
If the High Discharge Pressure switch fails, what saves the compressor?
The internal or external relief valve. Relieves from the High side to the Low side of the compressor.
What is the receiver's function?
1. Storage for refrigerant
2. Allows for surges
3. Maintains a liquid seal to the TXV
Function of the King Solenoid valve.
Stops the flow of liquid refrigerant when the compressor stops on a safety switch or the stop button is depressed
Where is the Low pressure side of the refrigeration system?
Outlet of the TXV to the inlet of the compressor
Where is the High pressure side of the refrigeration system?
Outlet of the compressor to the inlet of the TXV
Explain the control of pressure and Temperature.
To little of temperature difference results in insufficient cooling and high humidity.

To much of a temperature difference, results in low humidity
What is the purpose of the Water Regulating Valve?
Regulates compressor discharge pressure. More heat load, more water allowed to the condenser.
What is the Thermal Expansion Valves purpose?
TXV meters the amount of liquid refrigerant into the evaporator coil according to heat load, and maintains superheat.