[D2L] 102A Refrigeration Principles Flashcards
Specific heat is the amount of heat required to changed one pound of substance by one Fahrenheit degree.
T or F
True
All matter is composed of molecules that are in constant motion.
T or F
True
As water is heated the molecules tend to slow down.
T or F
False, the molecules tend to speed up
Which of the following statements is true?
1) An increase in work equals an decrease in heat.
2) A decrease in work equals a decrease in heat
3) A decrease in work equals an increase in heat
A decrease in work equals a decrease in heat
What two heat concepts affect refrigeration significantly?
Superheating vapours and subcooling liquids
What principle is needed between two objects in order to transfer heat?
There must be a temperature difference
Which method of heat transfer uses liquids and gases and involves fast vibrating molecules take up more space than slower vibrating molecules?
Convection
Which method of heat transfer is holding one end of a copper tube while heating the other end with an acetylene torch?
Conduction
Radiation can travel through space.
True
Energy transfers from a zone of low heat to high heat.
T or F
False, high to low
What kind of mechanical energy do we use to transfer from a low zone to a high zone?
1) pumps
2) compressors
3) fans
4) all of the above
All of the above
What is a Btu?
The amount of heat required to raise the temperature of 1lb of water by one Fahrenheit degree.
The unit for specific heat is Btu/lb/farenheit degree
T or F
True
Latent heat is a gain or loss of heat that is indicated by a rise or fall in temperature.
T or F
False
Latent heat is considered hidden heat because it does not register on a thermometer.
T or F
True
What is the freezing temperature for water?
1) 32F
2) 32C
3) 0C
4) both a&c
both a&c
32F, 0C
What makes up the sum of total heat?
1) sensible heat
2) latent heat
3) both
both sensible heat & latent heat
What is dry bulb temperature?
the sensible temperature of the air determined with a dry thermometer
What is the definition of pressure?
Force applied over an area
Which has the fastest moving molecules?
1) A hot cup of water
2) a cold cup of water
3) both hot and cold cups of water have the same rate of molecular motion
A hot cup of water
