Exam 3 Flashcards
The refrigerant in the condenser in a refrigeration system does what?
Rejects heat
The condenser in a refrigeration system
Desuper heats the vapour…
Condenses the vapour from the compressor
SubCool the liquid refrigerant before it leaves…
From the compressor
The condense
And normally operating water cold condensers operating with a 10°F differential between water in and water out. Is scale forms on the water tubes in the entering water is 85°F which of the following is possible?
Outlet water temperature will be lower than expect
And system head pressure will rise
In a water, cool condenser with dirty condenser tubes the temperature difference between the refrigerant and the water will be when the tubes are clean?
Greater than
The water circuit in shell and coil and tube within a tube coil condensers must be cleaned by what method?
Chemically
In a water, cool condenser, a regulating valve is used to control the…
Refrigerant head pressure
What can be used to maintain the head pressure system with the water glue condenser?
A water regulating valve
The typical design temperature for the water entering a recirculating water system condenser is 85°F and most systems have a white degree rise across the condenser?
10°
What is the most important parameter in cooling tower selection?
Entering wet bulb temperature
What is the importance of condenser subcooling?
It prevents flashing in the liquid line
True or false: the desired water flow through a condenser connected to a recirculating water system is approximately 3 gallons per minute per ton of refrigeration
True
What problem will happen if head pressure drops too low
The metering device will not be properly
If the compression ratio office system with the reciprocating compressor decreases the amount of refrigerant pump by the compressor, will…
Will increase
Most of the heat energy in the suction vapour entering the compressor is is what
Superheated from the evaporator
The temperature of the compressed gas leaving the compressor can best be described as
Very warm
Rotary compressors are used primarily in
Residential and light commercial air conditioning
The clearance volume of a compressor cylinder
Volume of the space between the bottom of the valve plate and the top of the piston at the top of the stroke
If liquid enters the compression chamber of a reciprocating compressor, what can it damage?
Valves and piston rings
The site glass on a semi herd compressor is used to allow light to enter the case to keep the oil warm
False
Bolted together, motor compressor assembly, sometimes referred to as a semi hermetic type
True
The compression ratio for an R2 two compressor operating with a 68.5 PSIG suction pressure and 260 psi G discharge pressure is
3.3
What is the primary function of the condenser?
It rejects heat
If the ambient is 78° in the condenser split is 30 what should be the condensing temperature?
Should be 48
How does an HPR valve raise condensing temperature?
It backs up refrigerant into the condenser
If the condensing temperature is 120°, what should be the temperature of the water leaving the water cooled condenser?
110•
Cooling towers design with the fan, pulling air through them are known as what type of tower
Induce draft
What is the difference between a hermetic and semi herd compressor?
The hermit has all parts, enclosed in a welded shell
What is a suction cooled compressor?
It has suction valves in the cylinder head
Why is lubrication important to a compressor
All moving metal services must have oil between them
What is the proper level of oil in the site glass of a Copeland compressor?
Anywhere in the site class as long as the top of the oil is visible
Detect system pressure is the service. Well stem should be in what position.
Mid seated or cracked
What position at the discharge valve will cause damage if the compressor is running
Front seat
What is the compression ratio of a compressor operating at 10 psi G suction and 235 psi e.g. head pressure
10 to one
What is a primary advantage of scroll compressor over reciprocating compressor?
As few moving parts
How do you raise a units condenser sub cooling
Clean the condenser
What is a primary function of the comp
Increase refrigerant, temperature pressure and pump  vapour refrigerant
The fresher in the middle of the condensers, the same as a pressure at the
Liquid line port on the outdoor unit
Where does the hot gas from the compressor? Enter the water cool condenser
Where the warm water is leaving the condenser
Why should condenser filters only be used if it is part of a regular scheduled maintenance program?
Condensers do not need filters
In order to find the sub cooling bowl, the saturated temperature of the fridge and in the condenser in the actual temperature of the liquid refrigerant________ must be known
Exiting the condenser
After the evaporator coil is clean, why should it be santized
To kill bacteria and deodorize the coil 
