THERMAL CONDUCTIVITY OF FIN MATERIAL SHOULD BE LARGE WHICH OF THE A...

4.

Thermal conductivity of fin material should be large

Which of the above statements are correct?

(a) 1, 2 and 3

(b) 1, 2 and 4

(c) 2, 3 and 4

(d) 1, 3 and 4

IES-16. Assertion (A): In a liquid-to-gas heat exchanger fins are provided in the

gas side.

[IES-2002]

Reason (R): The gas offers less thermal resistance than liquid

(a) Both A and R are individually true and R is the correct explanation of A

(b) Both A and R are individually true but R is not the correct explanation of A

(c) A is true but R is false

(d) A is false but R is true

IES-17. Assertion (A): Nusselt number is always greater than unity.

Reason (R): Nusselt number is the ratio of two thermal resistances, one

the thermal resistance which would be offered by the fluid, if it was

stationary and the other, the thermal resistance associated with

convective heat transfer coefficient at the surface.

[IES-2001]

Page 32 of 97

IES-18. Extended surfaces are used to increase the rate of heat transfer. When

the convective heat transfer coefficient h = mk, the addition of

extended surface will:

[IES-2010]

(a)

Increase the rate of heat transfer

(b)

Decrease the rate of heat transfer

(c)

Not increase the rate of heat transfer

(d)

Increase the rate of heat transfer when the length of the fin is very large

IES-19. Addition of fin to the surface increases the heat transfer if

hA KP

/

is:

(a) Equal to one

(b) Greater than one

[IES-1996]

(c) Less than one

(d) Greater than one but less than two

IES-20. Consider the following statements pertaining to heat transfer through

fins: [IES-1996]