Deck 22: Condensers

Question 1

The following style(s) can be found in air-cooled condensers: ____.

A) vertical airflow pattern, taking air into the bottom and discharging it out the top
B) air blowing horizontally through
C) taking air in at the sides and discharging it out the top
D) All of the above.

Answer 1

D

Question 2

The desired water flow through a condenser connected to a recirculating water system is approximately 3 gallons per minute per ton of refrigeration .

Answer 2

True

Question 3

If an R-12 refrigeration system has its air-cooled condensing unit on a roof with an ambient air temperature of 100°F and the condenser outlet temperature (refrigerant) is 115°F, with how much subcooling is the condenser operating ?

A) 15°F
B) 30°F
C) 100°F
D) 130°F

Answer 3

A

Question 4

In a water-cooled condenser with dirty condenser tubes, the temperature difference between the refrigerant and the leaving water will be ____ when the tubes are clean.

A) less than
B) greater than
C) the same as
D) slightly lower than

Question 5

In a water-cooled condenser, a regulating valve is used to control the ____.

A) refrigerant flow through the pressure reducing device
B) refrigerant head pressure
C) suction pressure
D) water temperature

Question 6

If the spring pressure of a water regulating valve is increased, the system head pressure will also increase.

Question 7

The typical design temperature for the water entering a recirculating water system condenser is 85°F, and most systems have a ____ rise across the condenser.

A) 1°F
B) 5°F
C) 10°F
D) 15°F

Question 8

The water circuit in shell-and-coil and tube-within-a-tube coil condensers must be cleaned ____.

A) by removing the end caps
B) with a brush
C) chemically
D) by air pressure

Question 9

What can be used to maintain the head pressure of a system with a water-cooled condenser?

A) Fan cycling.
B) Dampers or louvers.
C) Water regulating valve.
D) All of the above.

Question 10

Mineral deposits on the water side of a water-cooled condenser act as a(n) ____.

A) conductor of heat
B) insulator
C) cleaning solution
D) They have no effect on the operation of the condenser.

Question 11

The condenser in a refrigeration system ____.

A) desuperheats the vapor from the compressor
B) condenses the vapor from the compressor
C) subcools the liquid refrigerant before it leaves the condenser
D) All of the above.

Question 12

A water regulating valve helps to maintain a system's head pressure by modulating the flow of refrigerant through the condenser.

Question 13

A normally operating water-cooled condenser is operating with a 10°F differential between water in and water out. If scale forms on the water tubes and the entering water is 85°F, which of the following is possible ?

A) The outlet water temperature will be lower than expected.
B) The system head pressure will rise.
C) The water regulating valve will close.
D) Both a and b are correct.

Question 14

High head pressures from low ambients can cause insufficient refrigerant flow rates through metering devices, which in turn can starve evaporators .

Question 15

One big problem designers face when designing air-cooled refrigeration and air-conditioning equipment is the changing ambient of the changing seasons .

Question 16

When the evaporative condenser is used in cold climates, freeze protection must be provided in winter .

Question 17

Which of the following can be used to maintain the head pressure of a system with an air-cooled condenser?

A) Fan cycling.
B) Condenser flooding.
C) Dampers.
D) All of the above.

Question 18

The shell-and-tube condenser is cleaned ____.

A) with a brush after removing the end caps
B) only with chemicals
C) with compressed air
D) with a vacuum cleaner

Question 19

The refrigerant in a condenser in a refrigeration system ____.

A) absorbs heat
B) rejects heat
C) changes to a vapor
D) is under lower pressure than the evaporator

Question 20

An air-cooled condenser that is operating in a climate that has four distinct seasons must ____.

A) have some type of head pressure control
B) use a water regulating valve
C) have a multi-circuit evaporator
D) operate with zero degrees of subcooling

Question 21

Define "heat reclaim."

Question 22

An evaporative condenser uses air and ____________________ to desuperheat, condense, and subcool the refrigerant.

Question 23

What is the condenser saturation temperature if there is 20°F of subcooling and the outlet temperature of the refrigerant is 90°F?

Question 24

What would the symptom be if an air-cooled condenser had two fans and one stopped running?

Question 25

In a tube-within-a-tube condenser, the refrigerant flows in the outer tube and the water flows in the inner tube. Why?

Question 26

Hard starting may also occur in a low ambient condition, causing low head pressures .

Question 27

What is meant by the term blowdown?

Question 28

Describe the construction of the tube-within-a-tube condensers .

Question 29

Define "desuperheat."

Question 30

Define "subcooling."

Question 31

In order for a flooded condenser type head pressure control system to operate, a device called a(n) ____________________ holds the extra refrigerant in warmer weather when the condenser doesn't need to be flooded .

Question 32

Low suction pressures, iced coils, short cycling, and inefficient cooling, can also result from low head pressures .

Question 33

In a recirculating water system condenser, the leaving water temperature is normally ____________________°F lower than the condensing temperature of the refrigerant .

Question 34

The heat in the vicinity of the ____________________ gas has a tendency to cause any minerals in the water to deposit onto the tube surface.

Question 35

If an air-cooled condenser's fan motor stops running, the head pressure will ___________________ .