Deck 2: HVAC and Heating Systems: Understanding Compressors, Cooling Towers, Filters, and Heat Transfer Methods

Question 1

Which of the following is the condition to use two compressors in the refrigeration system?

A)the desired temperature is 3°c
B)the desired temperature is -3°c
C)the desired temperature is -50°c
D)the desired temperature is -5°c

Answer 1

the desired temperature is -50°c

Question 2

Centrifugal compressors are used to handle------------------ volume of refrigerant.

A)small
B)medium
C)large
D)very large

Answer 2

large

Question 3

Which of the following cooling towers possess maximum heat transfer from air to water?

A)natural draft
B)mechanical draft
C)natural and mechanical draft
D)atmospheric draft

Answer 3

mechanical draft

Question 4

Which of the following is true about the optimum effective temperature for human comfort?

A)same in winter and summer
B)not dependent on season
C)lower in winter than in summer
D)higher in winter than in summer

Question 5

When the heat stored in the body is-------------- the human body feels comfortable.

A)zero
B)infinite
C)positive
D)negative

Question 6

Room air conditioners and packaged units are examples of

A)direct expansion systems
B)indirect expansion systems
C)chilled water systems
D)indirect contraction systems

Question 7

Which of the following types of filters used in the air conditioning system is made of cloth that is discarded on getting dirty?

A)viscous type filters
B)dry filter
C)spray washers
D)electric precipitators

Question 8

The process of extraction of the certain required amount of water from air is known as                        

A)heating
B)cooling
C)humidification
D)dehumidification

Question 9

Which of the following is capable of absorbing excess moisture from the air?

A)silica gel
B)charcoal
C)salts of calcium or ammonia
D)activated alumina

Question 10

Magnetic materials are heated with the help of

A)hysteresis loss
B)electric arc
C)electric current
D)radiation.

Question 11

In the indirect resistance heating method, heat is delivered to the charge

A)direcly
B)by radiation
C)by convection
D)both (b) and (c).

Question 12

Electric ovens using heating elements of........................... can produce temperatures up to 3000°C

A)nickel
B)graphite
C)chromium
D)iron.

Question 13

Which of the following heating method is based on the transformer principle ?

A)resistance heating
B)eddy-current heating
C)induction heating
D)dielectric heating.

Question 14

Which of the following furnace suffers from pinch effect?

A)resistance furnace
B)core type induction furnace
C)coreless induction furnace
D)vertical core type induction furnace.

Question 15

The coreless induction furnace uses high-frequency electric supply in order to obtain high

A)flux density
B)eddy-current loss
C)primary resistance
D)power factor.

Question 16

Spot welding is used for

A)thin metal sheets
B)rough and irregular surfaces
C)costings only
D)thick sections

Question 17

Which of the following is an advantages of heating by electricity?

A)quicker operation
B)higher efficiency
C)absence of flue gases
D)all of the above

Question 18

...... has the highest value of thermal conductivity.

A)copper
B)aluminium
C)brass
D)steel

Question 19

...... method has leading power factor

A)resistance heating
B)dielectric heating
C)arc heating
D)induction heating

Question 20

Which of the following methods of heating is not dependent on the frequency of supply?

A)induction heating
B)dielectric heating
C)electric resistance heating
D)all of the above

Question 21

When a body reflects entire radiation incident on it, then it is known as

A)white body
B)grey body
C)black body
D)transparent body

Question 22

For the transmission of heat from one body to another

A)temperature of the two bodies must be different
B)both bodies must be solids
C)both bodies must be in contact
D)at least one of the bodies must have some source of heating

Question 23

A perfect black body is one that

A)transmits all incident radiations
B)absorbs all incident radions
C)reflects all incident radiations
D)absorbs, reflects and transmits all incident radiations

Question 24

Heat is transferred simultaneously by condition, convection and radiation

A)inside boiler furnaces
B)during melting of ice
C)through the surface of the insulted pipe caring steam
D)from refrigerator coils to freezer of a refrigerator

Question 25

The process of heat transfer during the re-entry of satellites and missiles, at very high speeds, into earth's atmosphere is known as

A)ablation
B)radiation
C)viscous dissipation
D)irradiation