Question: A grey body is one whose absorptivity does not vary with temperature and wave length of the incident ray.
[A].True
False
[A].
[B].
Answer: Option A
Explanation:
No answer description available for this question.
Heat Transfer
Emissivity of a body will be equal to its absorptivity at all temperatures.
Question: Emissivity of a body will be equal to its absorptivity at all temperatures.
[A].Yes
No
[A].
[B].
Answer: Option B
Explanation:
No answer description available for this question.
If the energy radiated per second per sq. cm. of the surface for wave lengths lying between λ, and λ + dλ is represented by (eλ.dλ), then eλ is called
Question: If the energy radiated per second per sq. cm. of the surface for wave lengths lying between λ, and λ + dλ is represented by (eλ.dλ), then eλ is called
[A].absorptive power
emissive power
emissivity
none of these
[A].
[B].
[C].
[D].
Answer: Option B
Explanation:
No answer description available for this question.
A perfect black body is one which
Question: A perfect black body is one which
[A].is black in colour
absorbs heat radiations of all wave lengths falling on it
reflects all the heat radiations
transmits the heat radiations
[A].
[B].
[C].
[D].
Answer: Option B
Explanation:
No answer description available for this question.
The amount of radiation mainly depends upon the
Question: The amount of radiation mainly depends upon the
[A].nature of the body
temperature of the body
type of surface of the body
all of these
[A].
[B].
[C].
[D].
Answer: Option D
Explanation:
No answer description available for this question.
Nusselt number (NN) is given by
Question: Nusselt number (NN) is given by
[A].
[A].
[B].
[C].
[D].
Answer: Option A
Explanation:
No answer description available for this question.
In free convection heat transfer transition from laminar to turbulent flow is governed by the critical value of the
Question: In free convection heat transfer transition from laminar to turbulent flow is governed by the critical value of the
[A].Reynold’s number
Grashoff’s number
Reynold’s number, Grashoff’s number
Prandtl number, Grashoff’s number
[A].
[B].
[C].
[D].
Answer: Option D
Explanation:
No answer description available for this question.
In a heat exchanger with one fluid evaporating or condensing, the surface area required is least in
Question: In a heat exchanger with one fluid evaporating or condensing, the surface area required is least in
[A].parallel flow
counter flow
cross flow
all of these
[A].
[B].
[C].
[D].
Answer: Option D
Explanation:
No answer description available for this question.
A designer chooses the values of fluid flow rates and specific heats in such a manner that the heat capacities of the two fluids are equal. A hot fluid enters the counter flow heat exchanger at 100° C and leaves at 60° C. A cold fluid enters the heat exchanger at 40° C. The mean temperature difference between the two fluids is
Question: A designer chooses the values of fluid flow rates and specific heats in such a manner that the heat capacities of the two fluids are equal. A hot fluid enters the counter flow heat exchanger at 100° C and leaves at 60° C. A cold fluid enters the heat exchanger at 40° C. The mean temperature difference between the two fluids is
[A].20°C
40°C
60°C
66.7°C
[A].
[B].
[C].
[D].
Answer: Option A
Explanation:
No answer description available for this question.
For evaporators and condensers, for the given conditions, the logarithmic mean temperature difference ™ for parallel flow is __________ that for counter flow.
Question: For evaporators and condensers, for the given conditions, the logarithmic mean temperature difference ™ for parallel flow is __________ that for counter flow.
[A].equal to
less than
greater than
[A].
[B].
[C].
Answer: Option A
Explanation:
No answer description available for this question.