Unit 3 Quiz Questions and notes
A "ton" of air conditioning capacity is _____________ Btu/h.
12,000
Which description below best describes "latent heat"?
A change of state is required to absorb or reject latent heat.
Reciprocating compressors have ___________________________________________.
A piston and a cylinder
The primary function of the air conditioning evaporator is to ________________________.
Absorb heat from the air blowing across it.
Which statement is most true about the benefit of subcooling liquid refrigerant before it enters the metering device?
Decreased flash gas will increase the amount of liquid available for refrigeration.
Which of the following best describes heat transfer?
Heat goes to cold.
Which is the most correct description of the basic theory about refrigeration?
Heat is transferred from where it is not wanted to where it makes no difference.
The primary function of the compressor is to _______________________________________.
Increase the pressure and temperature of refrigerant and to pump it through the system.
Evaporator.
It absorbs heat. The heat in the air passing over the coils is absorbed into the refrigerant as the heat causes the refrigerant to boil. When all the refrigerant is evaporated it is pulled into the compressor. low pressure/low temperature saturated liquid in -> low pressure/low temperature superheated vapor out
Compressor.
It is the heart of the system and has 3 primary functions: Reduces the pressure and temperature in the evaporator. Increases the pressure and temperature in the condenser. Pumps refrigerant through the system. Low Pressure/Low temp superheated vapor in -> high pressure/high temperature superheated vapor out
Metering device.
It lowers the temperature and pressure of the condenser's liquid refrigerant as it sprays it into the evaporator in the form of droplets of liquid. high pressure/warm temperature subcooled liquid in -> low pressure/low temperature saturated liquid out
Condenser.
It rejects heat. The heat in the hot vapor from the compressor is absorbed by the cooler outdoor air as the refrigerant is condensed into a liquid. high pressure/high temperature superheated vapor in -> high pressure/warm temperature subcooled liquid out
Which statement best describes adiabatic expansion inside a metering device?
Some liquid refrigerant flashes off to cool the remaining refrigerant.
Which of the following best describes boiling point and the state of a refrigerant?
Super heated is when a refrigerant's sensible temperature is above its boiling point. Subcooled is when a refrigerant's sensible temperature is below its boiling point.
Which is the most important statement about the temperature/pressure relationship?
The boiling point of refrigerant is controlled by controlling its pressure.
Discharge/hot gas line
connects compressor outlet to condenser inlet. refrigerant state = high pressure/high temperature superheated vapor
liquid line
connects condenser outlet to metering device inlet. refrigerant state = high pressure/warm temperature subcooled liquid
Suction Line
connects evaporator outlet to compressor inlet. refrigerant state = Low Pressure/Low temp superheated vapor
no name line
connects metering device outlet to evaporator inlet. refrigerant state = low pressure/low temperature saturated liquid
The "saturation" temperature on a refrigerant P/T chart is its temperature _____________.
when there is both liquid and vapor present at the same time.
