PPT 6 Flashcards
Which of the following is true?
a. The thermal conductivity of
aluminum is higher than silver
b. Aluminum and silver transfer heat at
the same rate
c. Silver is faster to transmit heat than
aluminum
d. All of the above
c. Silver is faster to transmit heat than
aluminum
If the flow of fluid is on streamline
characteristics, the fluid is at …
a. Turbulent condition
b. Laminar condition
c. Eddies
d. All of the above
b. Laminar condition
One BTU/hr-ft-F is equal to:
a. 0.00413 cal/sec-cm-C
b. 1/448 kcal/hr-m-C
c. 0.0173 w/cm-C
d. All of the above
e. None of the above
d. All of the above
The Prantdl number is a function of
______.
a. Viscosity, specific heat, and
thermal conductivity
b. Viscosity, diameter of pipe, thermal
conductivity
c. Specific heat, heat transfer
coefficient, and thermal
conductivity
d. None of the above
a. Viscosity, specific heat, and
thermal conductivity
Heat transfer coefficient by force
convection is determined by what
dimensionless numbers?
a. Nusselt, Prandtl, Reynolds
b. Nusselt, Prandtl, Grashof
c. Reynolds, Grashof, Prandtl
d. None of the above
a. Nusselt, Prandtl, Reynolds
One British thermal unit is equal
to _____
a. 1055 J
b. 1505 J
c. 1550 J
d. None of the above
a. 1055 J
If the heated pipe is changed to a
higher pipe schedule, the heat
transfer will:
a. Increase
b. Decrease
c. Remains the same
d. All of the above
b. Decrease
Basically, the thermal conductivity of a
material will increase if the ______
a. Thickness is increased
b. Temperature is increased
c. Temperature is
decreased
d. All of the above
b. Temperature is increased
Which of the following
statement is true?
a. Heat transfer rate is higher on
edges of boxes
b. Heat transfer rate is lower on
the walls of boxes
c. Heat transfer rate is higher on
corners of boxes
d. None of the above
a. Heat transfer rate is higher on
edges of boxes
A good insulator for kiln dryer.
a. Rice husk
b. Brick
c. Concrete
d. None of the abov
b. Brick
A material which is conductor of
heat or has low thermal
conductivity.
a. Conductor
b. Insulator
c. Resistor
d. All of the above
b. Insulator
An example of a good insulating
material at high temperature.
a. Iron
b. Wood
c. Asbestos
d. All of the above
c. Asbestos
Which of the following has low
thermal conductivity?
a. Building brick
b. Asbestos
c. Firebrick
d. Concrete
b. Asbestos
Insulators used for steam lines
are classified into:
a. Low temperature range
insulator
b. High temperature range
insulator
c. Medium temperature range
insulator
d. None of the above
c. Medium temperature range
insulator
A good example of a dual
temperature insulator.
a. Expanded silica
b. Cellular glass
c. Vermiculite
d. All of the above
d. All of the above
Form of insulants used in
industrial insulation practice.
a. Flexible strips
b. Foil
c. Flexible pipe section and
mattresses
d. All of the above
d. All of the above
Which of the following statement is
true?
a. In insulation, heat gain is more
costly than heat loss
b. The cost of extracting heat from
refrigerated space is the same
with the cost of heat losses from
a high temperature system
c. The cost of insulating high
temperature system is the same
with that of low temperature
system
d. All of the above
a. In insulation, heat gain is more
costly than heat loss
Moisture in low-temperature
insulation material may cause:
a. Reduction in the insulating value of
the material
b. To decrease the cost of the
insulating materials
c. Improvement in the insulating value
of the materials
d. All of the above
a. Reduction in the insulating value of
the material
An example of materials used
for low-temperature systems.
a. Urethane foam
b. PVC foam
c. Cellular glass
d. All of the above
d. All of the above
It is an extruded foam used for
low temperature systems such
as refrigeration, Building, and
sub-zero insulation.
a. Polystyrene foam
b. PVC foam
c. Plastic foam
d. All of the above
a. Polystyrene foam
It is essentially a ceramic material
designed to resist high temperature of
1000 to 1800 C.
a. Refractory
b. Asbestos
c. Fiber glass
d. None of the above
a. Refractory
Factor that need to be considered in
selecting insulants…
a. Operating temperature
b. Maintenance cost
c. Ability to resist
d. Mechanical and heat damage
e. All of the above
e. All of the above
To protect insulant from
mechanical damage, the
insulant must be provided with
a. Metal sheet cladding
b. Nets and asbestos cement
c. Wire net and bituminous
compound
d. All of the above
d. All of the above
The Stefan - Boltzmann
constant is equal to:
a. 0.147 x 10-8BTU/hr-ft2-F4
b. 0.174 x 10-8BTU/hr-ft2-F4
c. 0.174 x 10-8BTU/hr-ft2-F3
d. None of the above
c. 0.174 x 10-8BTU/hr-ft2-F3
The equation for heat transfer by
radiation for gray bodies is
a. Qr = AT4
b. Qr = εAT4
c. Qr = εAT4
d. None of the above
b. Qr = εAT4
It is a device used for
transferring heat.
a. Insulator
b. Heat absorber
c. Heat exchanger
d. All of the above
c. Heat exchanger
The overall heat transfer
coefficient includes…
a. Thermal conductivity and heat
transfer coefficient of the materials
b. Heat transfer coefficient and
emmissivity of the materials
c. Thermal conductivity and
emmissivity of the materials
d. None of the above
a. Thermal conductivity and heat
transfer coefficient of the materials
Which of the following
statement is true?
a. When radiant energy falls on a body,
part may be reflected, absorbed and the
remainder transmitted.
b. When radiant energy fall on a body,
part may be reflected and absorbed.
c. When radiant fall on a body, all of the
energy are absorbed.
d. None of the above
a. When radiant energy falls on a body,
part may be reflected, absorbed and the
remainder transmitted.
When two fluids in a heat
exchanger move in opposite
direction, the device is classified
as
a. Parallel flow HE
b. Cross flow HE
c. Constant flow HE
d. None of the above
b. Cross flow HE
Configuration factor for parallel planes
in calculating the heat radiated is
a. Higher than perpendicular
planes
b. Equal to perpendicular planes
c. Lower for perpendicular planes
d. None of the above
a. Higher than perpendicular
planes
It is the process of removing heat from
a substance or a space at a lower
temperature.
a. Sublimation
b. Heat of fusion
c. Refrigeration
d. All of the above
c. Refrigeration
Heat moves from a substance
naturally to another substance
a. At a higher temperature to
lower temperature
b. Al lower temperature to
higher temperature
c. At either temperature
d. None of the above
a. At a higher temperature to
lower temperature
It is the intensity of the
molecular movement of matter.
a. Energy
b. Heat
c. Work
d. All of the above
b. Heat
A substance is cold if
a. Heat is present
b. Heat is absent
c. Heat is higher
d. All of the above
b. Heat is absent
Ten BTU is equivalent to
a. 2520 calories
b. 2250 calories
c. 2045 calories
d. None of the above
a. 2520 calories
The quantity of heat in the
substance is described in terms
of
a. BTU
b. Calories
c. Pascal
d. All of the above
d. All of the above
One-hundred calories is
equivalent to:
a. 418.7 Joules
b. 481.7 Joules
c. 471.8 Joules
d. None of the above
a. 418.7 Joules
An instrument used to measure
heat is
a. Thermometer
b. Watt meter
c. Calorimeter
d. None of the above
c. Calorimeter