Deck 28: Special Refrigeration Applications

Question 1

Ammonia is extremely toxic to humans and must be used with care.  When working with ammonia systems it is often necessary for the technician to wear ____ .

A) gogles
B) breathing apparatus
C) protective clothing
D) All of the above.

Answer 1

D

Question 2

The process where a solid changes directly to a vapor without first becoming a liquid is called ____________________.

Answer 2

sublimation

Question 3

Where are cascade systems primarily used?

A) Extra-low temperature range.
B) Low temperature range.
C) Medium and low temperature ranges.
D) Medium temperature range.

Answer 3

A

Question 4

Nitrogen changes from a liquid to a vapor at ____.

A) 212°F
B) -21°F
C) -320°F
D) -479°F

Question 5

In a cascade system, the condensing refrigerant in one stage is used to evaporate the refrigerant in another stage .

Question 6

Water-cooled condensers using sea water are usually designed and built to permit periodic cleaning by ____ .

A) brushing the tubes
B) acid treatment
C) back finishing
D) All of the above.

Question 7

In order to keep dry ice in the solid form, the temperature of its surroundings can be ____.

A) 30°F
B) -41°F
C) -100°F
D) -125°F

Question 8

Seawater-cooled condensers for marine use have ____ .

A) removable water box covers
B) water circulating in the tubes
C) tubes that are accessible for cleaning using a brush
D) All of the above.

Question 9

Refrigeration systems that use nothing more than a thermostatically controlled solenoid valve feeding a distribution system can use ____________________ or carbon dioxide as their refrigerant.

Question 10

Truck refrigeration systems are designed to have the capacity to ____ .

A) refrigerate a load that is not down to temperature
B) refreeze a load that has thawed
C) hold the load temperature when in transit
D) All of the above.

Question 11

Dry ice is composed of ____.

A) liquid nitrogen
B) liquid carbon dioxide
C) solidified carbon dioxide
D) solidified ammonia

Question 12

The axle-driven refrigeration unit is a new system very commonly used in today's railway refrigeration .

Question 13

At extremely low evaporator temperatures, the compression ratio for the compressor becomes too great for single-stage refrigeration .

Question 14

Refrigerated trucks are equipped with systems that are designed primarily to maintain a product's temperature while being transported.

Question 15

A system that uses two or more refrigeration systems working at the same time and exchanging heat between them to produce ultra-low temperatures, is called a(n) ____________________ system .

Question 16

Cargo ship refrigeration units are usually sized with very little reserve capacity .

Question 17

Cold plates are usually filled with a ____.

A) brine solution
B) eutectic solution
C) sodium chloride or calcium chloride solution
D) All of the above.

Question 18

A eutectic solution is a(n) ____.

A) phase change solution
B) very warm solution
C) acid solution
D) explosive solution

Question 19

Because of the large capacities of refrigeration systems installed in trucks, the trucks themselves do not need to be insulated from outside ambient temperatures.

Question 20

In some applications of truck refrigeration, a liquid refrigerant is sprayed directly into the truck box to maintain low temperatures. The liquid refrigerant used is ____.

A) oxygen
B) nitrogen
C) R22
D) ammonia

Question 21

The blast freeze method is done at very low temperatures and a high air   ____________________ .

Question 22

Nitrogen is not suitable for breathing because it has no ____________________ in it .

Question 23

Why are phase-change (eutectic) solutions used inside the cold plates mounted in the walls or ceiling of trucks ?

Question 24

The system of shipping refrigerated trucks loaded on railcars is known as "____________________ ."

Question 25

Some products, such as chicken, are dip frozen in a very cold solution of brine, in the first stage of the freezing process. Why ?

Question 26

Why is the quality of meats frozen in a home freezer inferior to that of commercially frozen meats ?

Question 27

When products need to be cooled during flight, ice or ____________________ is used .