Important questions about Convective Heat Transfer. Convective Heat Transfer MCQ questions with answers. Convective Heat Transfer exam questions and answers for students and interviews.

How many types of fluid flow are characterized in the realms of fluid mechanics?

Options

A : a. 1

B : b. 2

C : c. 3

D : d. 4

In which fluid flow, the motion of fluid particles is irregular?

Options

A : a. Turbulent

B : b. Laminar

C : c. One dimensional

D : d. Two dimensional

Following are the characteristics of turbulent flow (i) Eddying (ii) Sinuous (iii) Rectilinear Identify the correct option

Options

A : a. 2 and 3

B : b. 1 and 3

C : c. 1, 2 and 3

D : d. 1 and 2

The nature of fluid flow is governed by following parameters (i) Mean flow velocity (ii) Density of fluid (iii) Dynamic viscosity of the fluid Identify the correct statements

Options

A : a. 1 and 3

B : b. 1 only

C : c. 1, 2 and 3

D : d. 2 and 3

The value of convective coefficient of air in case of free convection is

Options

A : a. 3-7 W/m² K

B : b. 3-4 W/m² K

C : c. 8-9 W/m² K

D : d. 9-9.5 W/m² K

The fluid particles move in flat or curved un-mixing layers or streams and follow a smooth continuous path. This type of flow is known as

Options

A : a. Steady flow

B : b. Stream flow

C : c. Turbulent flow

D : d. Laminar flow

The characteristic dimension d in the relation R E = V d p/? is the equivalent diameter and is defined as how many times the cross-sectional flow area divided by wetted perimeter

Options

A : a. 7

B : b. 4

C : c. 1

D : d. 6

For a duct of rectangular cross-section with length l and breadth b, the value of d e is

Options

A : a. l b / l + b

B : b. 2 l b

C : c. 2 l b / l + b

D : d. 4 l b / l + b

In many flow situations, the duct can be (i) Circular (ii) Rectangle (iii) Trapezoidal (iv) Annulus Identify the correct option

Options

A : a. 1 and 2

B : b. 1, 2, 3 and 4

C : c. 1, 2 and 3

D : d. 3 and 4

If an annulus has an inner diameter of d? and an outer diameter of d? then the equivalent diameter is

Options

A : a. 2 d? – d?

B : b. d? – 2 d?

C : c. d? – d?

D : d. d? – d?

Conduction plus fluid flow in motion is known as

Options

A : a. Radiation

B : b. Conduction

C : c. Convection

D : d. Heat exchanger

How many types of convection are there?

Options

A : a. 4

B : b. 3

C : c. 2

D : d. 1

Which of the following heat flow situations pertains to free or natural convection?

Options

A : a. Air conditioning installations and nuclear reactors

B : b. Flow of water inside the condenser tubes

C : c. Cooling of internal combustion engine

D : d. Cooling of billets in atmosphere

Mark the system where heat transfer is given by forced convection

Options

A : a. Chilling effect of cold wind on warm body

B : b. Fluid passing through the tubes of a condenser and other heat exchange equipment

C : c. Heat flow from a hot pavement to surrounding atmosphere

D : d. Heat exchange on the outside of cold and warm pipes

Forced convection in a liquid bath is caused by

Options

A : a. Intense stirring by an external agency

B : b. Molecular energy interactions

C : c. Density difference brought about by temperature gradients

D : d. Flow of electrons in a random fashion

A finned tube hot water radiator with a fan blowing air over it is kept in rooms during winter. The major portion of the heat transfer from the radiation is due to

Options

A : a. Combined conduction and radiation

B : b. Radiation to the surroundings

C : c. Better conduction

D : d. Convection to the air

A body cooling from 80 degree Celsius to 70 degree Celsius takes 10 minutes when left exposed to environmental conditions. If the body is to cool further from 70 degree Celsius to 60 degree Celsius under the same external conditions, it will take

Options

A : a. Same time of 10 minutes

B : b. More than 10 minutes

C : c. Less than 10 minutes

D : d. Time will depend upon the environmental conditions

On a summer day, a scooter rider feels more comfortable while on the move than while at a stop light because

Options

A : a. An object in motion captures less radiation

B : b. Air has a low specific heat and hence it is cooler

C : c. More heat is loss by convection and radiation while in motion

D : d. Air is transparent to radiation and hence it is cooler than the body

What is the value of convective coefficient of oil in case of forced convection?

Options

A : a. 1460-3000 W/m² K

B : b. 460-3000 W/m² K

C : c. 60-3000 W/m² K

D : d. 160-3000 W/m² K

A sphere, a cube and a thin circular plate, all made of the same material and having the same mass are initially heated to the temperature of 250 degree Celsius. When left in air at room temperature, what will be their response to cooling?

Options

A : a. Cube will cool faster than sphere but slower than the circular plate

B : b. They will cool at the same rate

C : c. Sphere will cool faster

D : d. Circular plate will cool at the slower rate