Test Questions Flashcards
All matter has
MASS
The density of a substance
Describes its mass to volume relationship.
Specific volume is used to what ?
Indicate the volume that a specific weight of gas will occupy
How many watts of electrical power are equal to 1 hp
746
Gas molecules travel
every direction ( d all the above
1 watt equals ?
3.413 BTUs
If water weighs 8.33 pounds per gallon it will take how many BTUs to raise the temperature of 4 gallons of water from 70°F to 72°F
66.7
Temperature is defined as what
The level of heat
One British thermal unit will raise the temperature of 1 pound of water how many degrees Fahrenheit
1 degree Fahrenheit
Ice melts in ice boxes because
All of the above
A ton of refrigeration is equivalent to how many BTUs?
288,000 BTU/24 hour
The evaporator in the refrigeration system is
The component where refrigerant boils and absorbs heat.
The compressor in a refrigeration system does what
It compresses the refrigerant and pumps the refrigeration through the system.
The Condenser
Rejects heat from the refrigerant.
Enthalpy describes
The amount of heat a substance contains from some starting point.
The quantity of heat expressed in BTU/lb that the refrigerant absorbs from the refrigerated space to produce useful cooling is called what
The Net refrigeration effect
The amount of heat in the BTU/lb that is given off by the system in the discharge line and the condenser is referred to as the what?
Total heat of rejection
According to the pressure/enthalpy chart, as refrigerant flows through the compressor…..
The pressure temperature and heat content of the refrigerant all increase.
One ton of refrigeration is
12000 BTU/hr
In which direction does heat flow ?
From a warm substance to a cold substance.
An increase in sensible heat causes what ?
A higher thermometer reading.
A change in latent heat causes a what ?
A change in phase or state
When Heat transfers by conduction it ….
Moves from molecule to molecule.
When heat is transferred by convection it…
Is transported from one place to another by air or fluid
When heat is transferred by radiation it
Moves through space air air and heats solid objects as.
PSIG is equal to ?
PSIA - 14.696
The latent heat of fusion for a water to ice transformation is what?
144 BTU/lb
Condensing spread is calculated by how?
Saturated conditioning temp - outdoor ambient (Normally 15-30 degrees Fahrenheit)
Approach Temp is calculated how ?
Liquid Line temperature - Outdoor ambient (normally 3 -15 )
Subcooling temp is calculated how ?
Saturated condensing temp - liquid line temp.
Evaporating spread is calculated by how ?
Entering air - saturated evaporating temp
Super heat spread
Suction line temp-saturated evaporating temperature. (Normally 12+)
What are the High side temperature readings ?
Condensing spread, Approach temperature , Subcooling Temperature
What are the Low side temperature readings ?
Evaporating spread, Superheat
Whose law states that the volume of a gas varies inversely with absolute pressure, as long as the temperature remains constant?
Boyle’s
Condenser does what 3 things?
- ) De-superheat
- ) Condenses
- ) Subcooling
How many BTUs are required to change 6 lbs of ice at 20 degrees Fahrenheit to steam at 220 ?
7830 BTUs
Specific heat of ICE and steam
.5 BTU/lb per degree
Specific heat of water
1 BTU/lb/degrees farenheit
Specific heat of vaporization is how many BTUs?
970 BTUs
