Heat Transfer (3151909) MCQs

MCQs of Heat Transfer From Extended Surfaces

Showing 1 to 10 out of 20 Questions
1 2
1.

The extended surface used for the enhancement of heat dissipation is

(a)

Convective coefficient
(b)

Fourier number
(c)

Fin
(d)

No finned surface
Answer:

Option (c)

2.

A steel rod (k = 30 W/m degree) 1 cm in diameter and 5 cm long protrudes from a wall which is maintained at 10 degree Celsius. The rod is insulated at its tip and is exposed to an environment with h = 50 W/m2 degree and t a = 30 degree Celsius. Calculate the fin efficiency

(a)

56.57%
(b)

 66.57%
(c)

76.57%
(d)

86.57%
Answer:

Option (b)

3.

In order to achieve maximum heat dissipation, the fin should be designed in such a way that has a

(a)

The maximum lateral surface towards the tip side of the fin
(b)

The minimum lateral surface near the centerline
(c)

The maximum lateral surface at the root side of the fin
(d)

The maximum lateral surface near the center of the fin
Answer:

Option (c)

4.

A steel rod (k = 30 W/m degree) 1 cm in diameter and 5 cm long protrudes from a wall which is maintained at 10 degree Celsius. The rod is insulated at its tip and is exposed to an environment with h = 50 W/m2 degree and T a = 30 degree Celsius. Calculate the rate of heat dissipation

(a)

2.658 W
(b)

3.658 W
(c)

4.658 W
(d)

5.658 W
Answer:

Option (b)

5.

On a heat transfer surface, fins are provided to

(a)

Increase turbulence in flow for enhancing heat transfer
(b)

Increase temperature gradient so as to enhance heat transfer
(c)

Pressure drop of the fluid should be minimized
(d)

Surface area is maximum to promote the rate of heat transfer
Answer:

Option (d)

6.

The general solution of the linear and homogenous differential equation (second form) is of the form

(a)

 

θ= C 1 e 2 m x + C 2 e – m x
(b)

θ=C1  e 3m x + C 2 e – m x
(c)

θ=C 1 e 4 m x + C 2 e – m x
(d)

θ=C 1 e m x + C 2 e – m x
Answer:

Option (d)

7.

For a steady flow of heat along a rod, the general equation is d2θ/dx2 – m2θ= 0. The value of constant m is

 

 

(a)

 (hP/kAC)
(b)

 (hP/kAC) 3/2
(c)

(hP/kAC) 1/2
(d)

(hP/kAC) 2
Answer:

Option (c)

8.

The temperature distribution in the case of the infinitely long fin is

(a)

T – Ta/T0 – Ta = mx
(b)

T – Ta/T0 – Ta =-mx
(c)

T – Ta/T0 – Ta = e-m x
(d)

T – Ta/T0 – Ta =log (m x)
Answer:

Option (c)

9.

 The rate of heat transfer in case of infinitely long fin is given by

(a)

 (hPkA) 1/2 (T0 – Ta)
(b)

(hPA) 1/2 (T0 – Ta)
(c)

(hkA) 1/2 (T0 – Ta)
(d)

(PkA) 1/2 (T0 – Ta)
Answer:

Option (a)

10.

The rate of heat transfer from the fin in case of fin insulated at the tip is

(a)

 (hPkA)1/2 (T0 – Ta) tanh ml
(b)

 (hkA)1/2 (T0 – Ta) tanh ml
(c)

 (hPA)1/2 (T0 – Ta) tanh ml
(d)

 (PkA)1/2 (T0 – Ta) tanh ml
Answer:

Option (a)

Showing 1 to 10 out of 20 Questions
1 2