Evaporator Pretest Quiz

Question 1

What is the function of the evaporator?

Answer 1

To absorb heat into the refrigerant system

Question 2

The word “evaporate” really doesn’t fit what happens to the refrigerant in an evaporator because;

a) as the refrigerant absorbs heat, it boils
b) as the refrigerant absorbs heat, it condenses
c) as the refrigerant absorbs heat, it changes temp
d) none of these are true, refrigerant in the evaporator evaporates the same way water evaporates from the kitchen counter in your home

Answer 2

a) as refrigerant absorbs heat, it boils

Question 3

The pressure temperature relationship in the evaporator is(

a) the evaporator is mainly a sensible heat transfer device
b) the evaporator is mainly a latent heat transfer device
c) refrigerant temperature and pressure changes very little in the evaporator
d) refrigerant temperature and pressure changes quite a lot in the evaporator

Answer 3

b) evap is mainly latent heat trnsf dev.

and

c) ref temp and press changes very little in the evap

Question 4

The other names for a dry expansion evaporator are a ______________ evaporator and a _____ evaporator

Answer 4

direct expansion and DX

Question 5

The flooded evaporator has the flow of refrigerant into it controlled so that it has;

a) mostly liquid refrigerant at its inlet but gas by the time it reaches its outlet
b) all its tubes wetted by liquid refrigerant from beginning to end
c) mostly liquid refrigerant at its outlet but gas at its inlet

Answer 5

b) all its tubes wetted by liquid refrigerant from beginning to end

Question 6

On residential and small commercial products you should expect to find ____ evaporators

Answer 6

DX

Question 7

The refrigerant leaving a flooded evaporator is;

a) just like that leaving a DX evap, slightly superheated
b) just like that leaving a DX evap, saturated
c) saturated, while that leaving a DX is slightly superheated

Answer 7

c)

Question 8

refrigerant leaving a flooded evaporator is saturated and refrigerant leaving a dry evaporator is slightly superheated

True or False

Answer 8

True

Question 9

Refrigerant entering a D-X evaporator is a mixture of _______ with _______

Answer 9

liquid with vapour

Question 10

Flash gas comes from:

a) heat absorbed by the ref through piping as it travels from the condenser to the MD
b) heat absorbed by the ref through the piping as it travels for the MD to the Evap
c) an internal heat transfer from some of the refrigerant to that which becomes flash gas
d) the pressure drop which occurs at the MD

Answer 10

c) internal heat transfer from some of the ref to that which becomes flash gas

and

d) pressure drop that occurs at MD

Question 11

As flash gas increases, evaporator capacity

a) increases
b) decreases
c) stays the same
d) it depends on the evaporator pressure

Answer 11

b) decreases

Question 12

Superheat is provided at the outlet of a DX evaporator mainly to ;

a) improve evaporator efficiency
b) increase evaporator capacity
c) protect the compressor
d) increases system capacity

Answer 12

c) protect the compressor

Question 13

An evaporator which fails to provide superheat at its outlet places which compressor in the most serious danger?

a) rotary
b) compliant scroll
c) reciprocating
d) screw
e) centrifugal
f) all equally

Answer 13

c) reciprocating

Question 14

Bare tube, finned tube, and plate-surface evaporators are types which allow us to categorize evaporators according to their:

Answer 14

construction

Question 15

T or F? A finned-tube evaporator is always the best choice for any job

Answer 15

False

Question 16

A “prime-surface” evap is one of which:

a) has primer sprayed on it to protect it
b) is either a plate-surface or plate-finned type
c) is either a bare-tube or plate-surface type
d) uses only the primary surface, without fins, to transfer heat

Answer 16

c) a bare-tube or plate-surface type

and

d) uses only primary surface, without fins, to transfer heat

Question 17

As the temperature of the medium which the evaporator cools goes down:

a) the number of coil rows tends to go _____
b) number of fins per inch tends to go ______
c) saturation temp of the refrigerant goes ______
d) the likelihood of forming ice on the coil goes ___

Answer 17

a) down
b) down
c) down
d) up

Question 18

A chiller is an evaporator designed to cool ______ on brine

Answer 18

water

Question 19

When the piping required for a job becomes extensive, water is ether than refrigerant because: (3)

a) it is less complicated
b) it is easier to install
c) it is less costly
d) it is smaller in diameter

Answer 19

a) it is less complicated
b) it is easier to install
c) it is less costly

Question 20

A packaged, reciprocating liquid chiller is most likely to use a ____ chiller while a centrifugal chiller has a _______ chiller

Answer 20

DX

Flooded

Question 21

Scale from water deposits Scale from water deposits will buildup and need to be removed periodically from: (2)

a) outside of the tubes of a DX chiller
b) inside of the tube of a DX chiller
c) outside of the tubes of a flooded chiller
d) inside of the tubes of a flooded chiller

Answer 21

a) the outside of the tubes of a DX chiller

and

d) the inside of the tubes of a flooded chiller