Exam 3 Flashcards

1
Q

The refrigerant in the condenser in a refrigeration system does what?

A

Rejects heat

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2
Q

The condenser in a refrigeration system

Desuper heats the vapour…
Condenses the vapour from the compressor

SubCool the liquid refrigerant before it leaves…

A

From the compressor

The condense

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3
Q

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?

A

Outlet water temperature will be lower than expect

And system head pressure will rise

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4
Q

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?

A

Greater than

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5
Q

The water circuit in shell and coil and tube within a tube coil condensers must be cleaned by what method?

A

Chemically

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6
Q

In a water, cool condenser, a regulating valve is used to control the…

A

Refrigerant head pressure

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7
Q

What can be used to maintain the head pressure system with the water glue condenser?

A

A water regulating valve

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8
Q

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?

A

10°

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9
Q

What is the most important parameter in cooling tower selection?

A

Entering wet bulb temperature

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10
Q

What is the importance of condenser subcooling?

A

It prevents flashing in the liquid line

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11
Q

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

A

True

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12
Q

What problem will happen if head pressure drops too low

A

The metering device will not be properly

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13
Q

If the compression ratio office system with the reciprocating compressor decreases the amount of refrigerant pump by the compressor, will…

A

Will increase

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14
Q

Most of the heat energy in the suction vapour entering the compressor is is what

A

Superheated from the evaporator

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15
Q

The temperature of the compressed gas leaving the compressor can best be described as

A

Very warm

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16
Q

Rotary compressors are used primarily in

A

Residential and light commercial air conditioning

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17
Q

The clearance volume of a compressor cylinder

A

Volume of the space between the bottom of the valve plate and the top of the piston at the top of the stroke

18
Q

If liquid enters the compression chamber of a reciprocating compressor, what can it damage?

A

Valves and piston rings

19
Q

The site glass on a semi herd compressor is used to allow light to enter the case to keep the oil warm

A

False

20
Q

Bolted together, motor compressor assembly, sometimes referred to as a semi hermetic type

A

True

21
Q

The compression ratio for an R2 two compressor operating with a 68.5 PSIG suction pressure and 260 psi G discharge pressure is

A

3.3

22
Q

What is the primary function of the condenser?

A

It rejects heat

23
Q

If the ambient is 78° in the condenser split is 30 what should be the condensing temperature?

A

Should be 48

24
Q

How does an HPR valve raise condensing temperature?

A

It backs up refrigerant into the condenser

25
Q

If the condensing temperature is 120°, what should be the temperature of the water leaving the water cooled condenser?

A

110•

26
Q

Cooling towers design with the fan, pulling air through them are known as what type of tower

A

Induce draft

27
Q

What is the difference between a hermetic and semi herd compressor?

A

The hermit has all parts, enclosed in a welded shell

28
Q

What is a suction cooled compressor?

A

It has suction valves in the cylinder head

29
Q

Why is lubrication important to a compressor

A

All moving metal services must have oil between them

30
Q

What is the proper level of oil in the site glass of a Copeland compressor?

A

Anywhere in the site class as long as the top of the oil is visible

31
Q

Detect system pressure is the service. Well stem should be in what position.

A

Mid seated or cracked

32
Q

What position at the discharge valve will cause damage if the compressor is running

A

Front seat

33
Q

What is the compression ratio of a compressor operating at 10 psi G suction and 235 psi e.g. head pressure

A

10 to one

34
Q

What is a primary advantage of scroll compressor over reciprocating compressor?

A

As few moving parts

35
Q

How do you raise a units condenser sub cooling

A

Clean the condenser

36
Q

What is a primary function of the comp

A

Increase refrigerant, temperature pressure and pump  vapour refrigerant

37
Q

The fresher in the middle of the condensers, the same as a pressure at the

A

Liquid line port on the outdoor unit

38
Q

Where does the hot gas from the compressor? Enter the water cool condenser

A

Where the warm water is leaving the condenser

39
Q

Why should condenser filters only be used if it is part of a regular scheduled maintenance program?

A

Condensers do not need filters

40
Q

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

A

Exiting the condenser

41
Q

After the evaporator coil is clean, why should it be santized

A

To kill bacteria and deodorize the coil