Chapter 10 - Air Conditioning And Refrigeration Flashcards
What unit of air conditioning are used when the area is close together, being used for similar purposes or have same humidity zones?
Forced air units
Once the type of air conditioning unit is chosen what is the next step?
to figure out the appropriate size
In a refrigeration system what is the major consideration?
Heat load calculation
What two types of air conditioning units are used?
Forced air and hot and chilled water system
What refrigerant is used in the absorption refrigeration system?
Either water, ammonia, or lithium bromide
Where is the expendable refrigeration system used?
Used in trucks, railroad cars, and shipping containers that contain perishable goods.
What 3 types of refrigerant is used in expendable refrigeration systems?
Liquid nitrogen, carbon dioxide, and liquid helium.
What type of refrigeration system moves heat from one area to another by the use of electrical energy?
Thermoelectric refrigerant systems
What refrigeration systems are used when ultra low temperatures are required?
Multistage refrigeration systems
What does TEV stand for?
Thermostatic expansion valve
Describe the refrigeration cycle
Enters through the compressor, condenser, metering device, and out the evaporator
At two stage compound system can attain a temperature at what degrees?
-80 degrees F
A three stage compound system can attain a temperature at what degrees?
-135 degrees F
What 2 groups are evaporates divided into?
1.evaporators that cool air that in turn cools the the product. 2. Evaporators that cool a liquid that in turn cools the product
What is a control device that responds to changes In temperature and directly or indirectly controls the temperature?
Thermostat
What 3 types of thermostats are used?
Heating, cooling and dual.
What is the common sensing element in a thermostat?
Bimetal (made of metal and brass)
What 3 categories are associated with electrical room thermostats?
Line voltage, low voltage and millivoltage
What does AEV stand for?
Automatic expansion valve
What is valve is the most widely used expansion device?
TEV
What is a receiver?
Storage tank for liquid refrigerant
What are the 4 types of single phase motors used in hermetic assemblies?
Split phase, capacitor start induction run, capacitor start capacitor run, and permanent split phase.
What type of single phase motor has a limited starting torque and is usually used with window air conditioners?
Split phase
What are the 2 basic types of circuits?
Load and control
What is a load?
Any device that consumes electrical energy
If an ohmeter reads zero what does that mean?
The winding is grounded
What is the difference in start and run capacitors?
Start- connected in series with starting windings. Run- connected in the circuit between the line side of the starting and running windings.
What type of starting relay is electromagnetic and is used with split phase, induction run motors?
Current
What’s the maximum temperature in a cascade refrigeration system?
-50 degrees F
3 R’s of refrigeration cycle?
reclaim, recycle, recover
Which refrigerant is being phased out?
R-22
Which refrigerant replaced the r-22?
R 410A
Which refrigerants can we use?
R 134A, R 407C, R410A R417A
