Ref and Air Cond. Tech Unit 3

Question 1

A refrigeration system that maintains a space at a temperature between 35 degrees Fahrenheit and 40 degrees fahrenheit would be classified as what type of system?

Answer 1

medium temperature

Question 2

A refrigeration system that is intended to provide comfort cooling would be classified as what type of system?

Answer 2

high temp

Question 3

One ton of refrigeration is the equivalent of moving heat at

Answer 3

12,000 btu/hr

Question 4

The basic refrigeration cycle can best be described as a

Answer 4

repeating vapour compression cycle

Question 5

Saturated R-410A at a pressure of 95psig will change at a temperature of

Answer 5

29 degrees fahrenheit - found in temp pressure chart on pg46 in ref. air cond. tech

Question 6

The evaporating pressure for R-22 is 76psig and the evaporator outlet temperature is 58 degrees fahrenheit. What is the evaporators superheat?

Answer 6

76 psig=46F

58F-46F = 13 degrees fahrenheit

Question 7

The state of refrigerant at the inlet of the evaporator is approx

Answer 7

75% liquid 25% vapour

Question 8

The state of the refrigerant at the outlet of the evaporator should be

Answer 8

superheated vapour

Question 9

The state of refrigerant at the outlet of the condenser should be?

Answer 9

100% sub-cooled liquid

Question 10

When an air-conditioning system operates in a vacuum, which of the following is true?

a) air will leak out of the system
b) refrigerant will leak out of the system
c) air will be pulled into the system
d) refrigerant will be pulled into the system

Answer 10

air will leak out of the system

Question 11

The expansion device is responsible for?

Answer 11

metering refrigerant flow into the evaporator

Question 12

A properly operating compressor should have ___%________at its inlet and ___%________at its outlet

Answer 12

100% vapour 100% vapour

Question 13

Of the following compressors, which is a residential compressor that is forgiving when it comes to having liquid entering it?

a) reciprocating compressor
b) scroll compressor
c) the rotary compressor
d) screw compressor

Answer 13

b) scroll compressor

Question 14

Which of the following statements is true with regards to reciprocating and rotary compressors?

a) rotary and reciprocating compressors with similar capacities are similarly used
b) both rotary and reciprocating compressors are equipped with suction and discharge valves
c) both rotary and reciprocating can be opened for service
d) for compressors with similar capacities, rotary compressors are smaller than reciprocating compressors

Answer 14

for compressors with similar capacities, rotary compressors are smaller than reciprocating compressors

Question 15

Rotary compressors are typically used for applications such as

Answer 15

window air conditioners, household refrigerators, and some residential air conditioning systems

Question 16

Rotary compressors are usually ______ than reciprocating compressors of the same capacity

Answer 16

smaller

Question 17

The scroll compressor is the most commonly used compressor in

Answer 17

newly manufactured residential and light commercial air conditioning equipment

Question 18

The colour coding for an R-22 refrigerant cylinder is?

Answer 18

green

Question 19

The colour coding for an R-404A refrigerant cylinder is

Answer 19

Rose

Question 20

Of the following refrigerants, which has the lowest global warming potential (GWP)?

Answer 20

R-1234yf

Question 21

The three processes commonly used to describe refrigerant handling care?

Answer 21

recovering, recycling, and reclaiming

Question 22

The term that is used to quantify the amount of heat absorbed in the evaporator is?

Answer 22

net refrigeration effect

Question 23

The three regions on a pressure/enthalpy chart are:

a) high pressure, low pressure, critical pressure
b) superheated vapour, superheated liquid, depressurized liquid
c) superheated vapour, sub-cooled liquid, saturated
d) high-pressure liquid, low-pressure gas, low-pressure liquid

Answer 23

superheated vapour, sub cooled liquid, saturated

Question 24

The thumbprint shaped region on the pressure/enthalpy chart is called the:

a) saturation curve
b) saturation cycle
c) superheated curve
d) superheated region

Answer 24

saturation curve

Question 25

One of the challenges of plotting an R-407C system on a pressure/enthalpy chart is that this refrigerant:

a) is a single-compound refrigerant with one pressure for each temp
b) has a significant temperature glide
c) is a binary blend of R-32 and R-125, making it unstable
d) is easily mistaken for R-134a and R-410A

Answer 25

b) it has a significant temperature glide

c) is a binary blend of R-32 and R-125, making it unstable