Modern Chap 22: Review questions

Question 1

Gravitational circulation of air is used by

a) forced draft
b) immersed
c) microchannel
d) natural-draft

Answer 1

d) natural draft

Question 2

A small, plain, tube evaporator submerged and mounted inside a container filled with a liquid that provides good heat transfer is a ________

a) forced-draft
b) immersed
c) microchannel
d) natural-draft

Answer 2

b) immersed evaporator

Question 3

An evaporator fabricated from two metal sheets, welded together, that form a series of passages through which refrigerant flow describes an __________
evaporator

a) fin-and-tube
b) immersed
c) microchannel
d) plate

Answer 3

d) plate evaporator

Question 4

An evaporator with refrigerant passages that are less than 1mm in diameter is an __________

a) fin and tube
b) immersed
c) microchannel
d) plate

Answer 4

c) microchannel

Question 5

The three variables by which defrost timers operate include all of the following , except ;

a) humidity
b) pressure
c) temperature
d) time

Answer 5

a) except humidity

Question 6

Excess moisture produced by a defrosting evaporator may be removed from a conditioned space or cabinet using a ___________ when the available drain is elevated or at a removed location

a) set of baffles
b) condensate pump
c) desiccant
d) pump down solenoid

Answer 6

b) condensate pump

Question 7

Evaporator defrosting that involves pumping refrigerant directly from the compressor discharge line into the evaporator tubing describes a ___________

a) hot gas
b) non freezing solution
c) pump down
d) off cycle

Answer 7

a) hot gas

Question 8

Evaporator defrosting that involves circulating a heated solution in tubing near and around the evaporator during the off cycle describes a __________ defrost

a) hot-gas
b) non-freezing solution
c) pump down
d) water

Answer 8

b) non-freezing solution

Question 9

An evaporator defrosting system that circulates air from the conditioned space over the evaporator during the off cycle is a ___________ defrost

a) hot gas
b) non freezing
c) pump down
d) off-cycle

Answer 9

d) off-cycle

Question 10

Water-cooled condensers are built in all the following designs, except;

a) shell and tube
b) shell and coil
c) tube within a tube
d) wet deck

Answer 10

a, b, c

Question 11

A condenser that uses sprayed water droplets and drafts from fans to produce an evaporative cooling effect on its coils that flow with hot refrigerant vapour is an ____________ condenser

a) air cooled
b) evaporative
c) microchannel
d) water cooled

Answer 11

b) evaporative condenser

Question 12

the purpose of grooves, ridges, and pattern surfaces on the inside surface of condenser tubing is to ________

a) increase heat transfer
b) look cool
c) prevent tubing corrosion
d) reduce heat transfer

Answer 12

a) increase heat transfer

Question 13

The primary need for head pressure control in commercial refrigeration systems is due to ________

a) high winds
b) low ambient temperature
c) rain
d) refrigerant overcharge

Answer 13

b) low ambient temperature

Question 14

With condenser louver head pressure controls, as head pressure rises, the louvers ___________

a) begin to close
b) begin to open
c) remain stationary
d) none of the above

Answer 14

b) begin to open

Question 15

When using fan speed control and cycling for head pressure control, a drop in head pressure will cause

a) all the fans to cycle on
b) fan speed to increase
c) fans to slow down or cycle off
d) both A and B

Answer 15

c) fans to slow down or cycle off

Question 16

A suction line-liquid line heat exchanger performs which of the following functions?

a) increases the formation of flash gas in the liquid line
b) it subcools refrigerant in the suction line
c) increases systems efficiency
d) prevent refrigerant in the suction line from evaporating

Answer 16

c) increases a systems efficiency

Question 17

A heat exchanger through which flows the liquid line refrigerant of a low-temperature refrigerant system and the low-side refrigerant of a high-temperature system called a

a) over chiller
b) super heater
c) sub cooler
d) under cooler

Answer 17

sub-cooler

Question 18

A heat recovery system uses the heat from a systems

a) discharge
b) liquid
c) suction
d) water

Answer 18

c) suction

Question 19

For _________ defrost, refrigerant is removed from the evaporator in order to increase heat transfer to the frost buildup

a) hot gas
b) non freezing
c) pump down
d) electric

Answer 19

c) pump down