# Test: Heat Transfer By Natural Convection - 1

## 10 Questions MCQ Test Heat Transfer | Test: Heat Transfer By Natural Convection - 1

Description
Attempt Test: Heat Transfer By Natural Convection - 1 | 10 questions in 30 minutes | Mock test for Chemical Engineering preparation | Free important questions MCQ to study Heat Transfer for Chemical Engineering Exam | Download free PDF with solutions
QUESTION: 1

Solution:
QUESTION: 2

Solution:
QUESTION: 3

### Choose the wrong statement with respect to Nusselt number and convective heat transfer coefficient

Solution:
QUESTION: 4

Which one of the following number represents the ratio of kinematic viscosity to thermal diffusivity?

Solution:

Prandtl number is the ratio of two transport properties i.e the ratio of momentum diffusivity and thermal diffusivity. Prandtl number controls the relation between the velocity and temperature distributions.

QUESTION: 5

Consider the following boundary layer for natural convection on a vertical plate and match accordingly:

Solution:

AA : Turbulent region on hot wall
BB : Laminar region on hot wall
CC: Laminar region on cold wall
DD: Turbulent region on cold wall
EE : Velocity profile for hot wall
FF : Velocity profile for cold wall
GG: Boundary layer for cold wall
HH : Boundary layer for hot wall..

QUESTION: 6

Which of the following parameter is a measure of the relative importance of natural convection in relation to forced convection?
All empirical parameters have their usual meaning.

Solution:

If (Gr/Re2) << 1, flow is primarily by forced convection
If (Gr/Re2) >> 1, flow is dominant by natural convection
If (Gr/Re2) ≌ 1, natural and forced convection are of same magnitude.

QUESTION: 7

This value governs the transition from laminar to turbulent flow in natural convection:

Solution:

In free convection heat transfer transition from laminar to turbulent flow is governed by the critical value of the Prandtl number, Grashoff's number

QUESTION: 8

The empirical correlation for natural convection is represented by
All empirical parameters have their usual meaning.

Solution:
QUESTION: 9

The Prandtl number will be lowest for

Solution:

QUESTION: 10

In respect of free convection over a vertical flat plate, the Nusselt number for laminar and turbulent flow varies respectively as

Solution:

for vertical plate,
Nu = 0.59 Ra1/4 for 104 < Ra < 109
Nu = 0.13 Ra1/3 for 1010 < Ra < 1013

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