Key Points Flashcards
The three states of matter are solid, liquid, and gas. Substances change state when laten heat is added or remove. Substances change temperature when sensible heat is added or remove.
True
Heat always flow from a material at a higher temperature to a material at a lower remperature
True
Density is the mass of a substance that fits into a specified volume.
True
Specific volume is the volume that a specific weght of gas will occupy under specific conditions
True
Refrigerants have a reletionship between temperature and pressure
True
A ton of cooling is the amount of cooling provided by melting (2000 lb) of ice withing a 24 hr period
True
A refrigerant is a chemical substance that boils at a low temperature and is used for transporting heat in a cooling system
True
A compressor is a mechanical device that compresses refrigerant vapor
True
A condenser is a heat exchanger that removes heat from a high-pressure refrigerant vapor
True
A metering device is a component of the refrigerant system that controls the flow of refrigerant into the evaporation
True
An evaporator is a heat exchanger through which heat is transferred to low-pressure liquid refrigerant
True
A liquid receiver is a storage tank for the collection of liquid refrigerant
True
A suction accumulator is a container located between the evaporator and the compressor that catches any liquid refrigerant before the refrigerant reaches the compressor and causes damage
True
A purge unit is a device used to maintain a system free of air and moisture
True
The two common types of cooling systems are direct-expansion system (direct-cooling systems) and chilled water system (indirect cooling system)
True
A direct-expansion system is a cooling systemin which the evaporator is in direct contact with the air in the building space
True
A chilled water system is a cooling system in which water or other liquid is chilled and circulated to the building space
True
The most common direct-expansion system used for cooling are iar conditioning and heat pumps
True
An air conditioner uses direc expansion of the refrigerant in the evaporator coil to cool the building interior air
True
A heat pump uses direct expansion of the refrigerant in an indoor coil to heat or cool the biulding’s interior air, while an outdoor coil used to absorb or reject the heat
True
An absortion chiller system is a nonmechanical refrigeration system that uses a fluid with the ability to absorb a vapor when it is cool and release a vapor when heated
True
An ammonia-water absorption chiller system is an absorption chiller system that uses ammonia as the refrigerant and a solution of ammonia and water as the absorbent
True
A lithium bromide-water absorpion chiller is an absorption chiller system that uses water as the refrigerant and a solution of lithium bromide and water as the absorbent
True
Many refrigerants have been found to damage the environent
True
The three classifications of refrigerant most technicians work with today are chlorofluorocarbons (CFCs). Hydrochlorofluorocarbon (HCFCs) and hydrofluorocarbons (HFCs).
True
Service technicians must be certified in order to purchase and handle refrigerants. The four certifications are Type I, Type II, Type III, and Universal
True
Technicians may not knowengly vent or otherwise release or dispose of any substance used as a refrigerant in a manner that permits such substance to enter the environment. Refrigerants must be recovered, recycled, or reclaimed.
True
Refrigerants can cause frostbite to unprotected skin and freezing of the eyes, and can create environment problems in the form of ozone depletion and global warming.
True
