Tpc 431 Flashcards
Refrigeration is the process of…
Cooling, lowering the temperature of a space or a substance to a level below that of the area around it
What is the basics of heat transfer?
When heat moves from one substance to another, it always goes from the warmer substance to the cooler substance
What are the two reasons for air conditioning?
Comfort air conditioning & Process air conditioning
Matter exist in three physical states, they are…
Solid, liquid, and gas
The state of a substance depends upon its?
Temperature and pressure, the process involves the addition or removal of heat
What is thermal kinetic energy ( sensible heat )?
This kind of heat energy is directly related to temperature, the “hotness” or “coldness” of the object. It can be sensed through physical contact
Temperature conversions for F to C?
C = 5/9 ( F - 32 )
What are the three different methods of heat transfer?
Conduction, Radiation, Convection
All substances that change from a liquid form to a vapor or a gas go through what stage?
Latent heat of vaporization
Where does the compressor discharge the vapor to in the system?
The condenser
When a vapor is at a temperature above its boiling point we say it is?
Superheated
What evaporators cool more efficiently than dry-expansion types?
Flooded evaporators
In refrigerant to liquid evaporators the chilled liquid usually acts as a…
Secondary refrigerant, and absorbs heat from the substance to be cooled
What maintains constant pressure in the evaporator?
An automatic expansion valve
The air properties that are important in psychometrics are?
Temperature, Humidity, Specific volume and Enthalpy
The wet-bulb thermometer will have a lower reading than the dry-bulb thermometer if…
The air is not completely saturated
When is air at dewpoint temperature?
When it is fully saturated
Specific humidity is independent of…
Dry-bulb temperature
Enthalpy ( total heat ) is…
The sum of the sensible heat of the air, plus the sensible and latent heat of the water vapor present
What must you do if air and moisture enter the system?
You must remove ( evacuate ) them from the system with a vacuum pump after you finish making repairs
What is the most sensitive type of leak detector?
Electronic leak detector
What does a hygrometer measure?
It’s an instrument that measures relative humidity directly
Resistance is measured in?
Ohms
Refrigerant falls under what type of hazard?
Chemical hazards
