Refrigeration and Basic HVAC Systems Flashcards
A _____ system is one which the evaporator coil comes into direct contact with the medium to be cooled.
Direct
Skating rinks use _____ as the medium to obtain low temperatures necessary for the ice surface and prevent the secondary refrigerant from freezing.
Brine
In an ammonia absorption system, the ammonia is heated into a vapor by a _____ coil located in the generator (concentrator).
Steam
In an ammonia absorption system, the condenser would change the high pressure vapor into high pressure ______.
Liquids
In an ammonia absorption system, the ______________ would separate the high side condenser from the low side evaporator.
Metering Valve
In an ammonia absorption system, the secondary refrigerant located in the evaporator would be ________ when used in a building cooling system.
Chilled Water
Refrigeration is the science of producing and maintaining temperatures below that of the surrounding ________ by transferring heat from one place to another.
Atmosphere
Refrigeration engineers, particularly those associated with ________, finally decided to call all fluids used in refrigeration systems refrigerants with an identification number to cover all refrigerants.
ASHRAE
The ________ components of these refrigerants have been found to contribute significantly to the depletion of the ozone layer.
Chlorine
Group _____ refrigerants are considered dangerous and should only be used for industrial applications.
A3
The presence of escaping refrigerant will cause the flame of a ________ torch to turn green if there is a small leak or dense blue if there is a large leak.
Halide
Refrigeration R-717, more commonly known as _________, is one of the oldest refrigerants and because of its heat-absorbing ability is considered one of the best.
Ammonia
Too much oil accumulation in the ______ and ________ could cause there to be a shortage of oil in the crankcase of the compressor.
Evaporator and condenser
In the mid 1980s, the ______ _______ was established to ban, limit, and replace the existing CFC type refrigerants.
Montreal Protocol
The new refrigerants use _________ oil.
Polyester
A piston type compressor is classified as _________.
Reciprocating
_________ units contain a compressor that is directly coupled to an electric motor, both of which are sealed inside a welded steel case.
Hermetic
An ________ type compressor will have a shaft protruding outside of the body connected to a motor by either a pulley or a direct drive coupling.
Open
The evaporators will ______ the heat from the medium being cooled.
Absorb
The compressor generates the high and low side of the system; it will also create ________ ___ ___________ when the refrigerant passes through the exhaust portion of the compression cycle.
Heat of Compression
The type of evaporator that is widely used in air conditioning applications where the dry or direct expansion method is used would be a ___________ coil type.
Finned Tube
The shell and tube evaporator is referred to as a _______ and is used to cool a secondary refrigerant.
Chiller
The three basic types of condensers are _________, ____________, and ___________.
Air Cooled, Water Cooled, and Evaporative
To increase condenser capacity, air can be forced or drawn through the condenser could by means of ______ or ______.
Blowers or Fans
The evaporative condenser uses both conduction and evaporation for the rejection of the heat process. To make up water due to the evaporation process, you would install a ___________ in the pan.
Float Valve
To remove non-condensable gases and moisture prior to adding refrigerant to the system; the entire system would need to be _________.
Evacuated
Liquid receivers are built to the ASME _________ code.
Section VIII
The flow control device establishes a pressure differential between the ________ and the ________.
Condenser and Evaporator
_______ type metering valves are used in conjunction with the flooded evaporator.
Float
________ _________ is not suitable for air conditioning systems where the load is frequently changed since they do not respond to changes in temperature.
Constant pressure
The __________ valve opens and closes in response to the downstream superheated temperatures of the evaporator.
Thermostatic
The orifice or capillary tube will allow the refrigerant in the system to ________ _________ when the compressor is off.
Equalize pressure
The high side of a refrigeration system would not include:
An intake valve on compressor
A flooded evaporator would have a ________ metering valve.
High side float
An example of an indirect refrigeration system is a:
Pipe coil in a curling rink
Where a condenser is used, the best type for heat removal is an:
Evaporative
The type of metering valve that is manually operated and will require continuous supervision is the:
Needle valve
The thermostatic metering valve operates by sensing:
Superheat
The type of valve that senses temperature change with a thermistor is a:
Thermal-electric valve
A one pipe system is ideally suited for:
Perimeter baseboard installations
A three pipe system will not contain:
A split AC system
A chilled water coil will be:
Piped opposite of the steam coil.
The three (3) most important principles of air factors used on an air conditioning system is:
Temperature, humidification and air motion
Bacteria and disease can be controlled by using:
Filtration
A priority of air conditioning in pulp mills is to:
Reduce the amount of humidity
(T/F) Heat always flows from a lower temperature substance to a higher temperature substance.
False
(T/F) A heat pump can be used for both heating and cooling, regardless of the season.
True
(T/F) The water source is the most common type of energy source used for a heat pump.
False
(T/F) Geothermal heat pumps can be classified as either open loop or closed loop systems.
True
(T/F) There are only two heat pump cycles.
True
(T/F) The variable heat pumps have moving dampers and a fixed refrigeration cycle.
False
The type of filter that can be reused and regenerated using an oil based substance is:
Viscous impingement type
The most common type of fan or blower used on a furnace or an RTU is the:
Squirrel cage fan
The type of air conditioning equipment that requires the most service is the:
RTU - unitary
Downstream of a dual-duct mechanical room, each air conditioned room or area is required to have a _________ installed.
Mixing box
The type of ducting designed for high-velocity ducting is a:
Round duct
An essential item required on a steam heating coil with an automatic control valve is a:
Vacuum breaker
The type of coil design that is used when air temperature across a coil is greater than 35°F and 55°F is:
Installed two deep
Cooling towers are interconnected to:
Condensers
The most common energy source for a heat pump is:
Air source
A variable heat pump system will have:
Two metering valves
The fixed heat pump system will control the heat/cool cycle by the use of:
Motorized dampers
Icing of the evaporator is caused by:
Low refrigerant pressure in the evaporator
The receiver on a refrigeration system is located:
Upstream of the filter/ dryer
The safety valve from a receiver should be piped:
Away from air intakes
