MCQs of Convection (Heat Transfer - 3151909)

Heat Transfer (3151909) MCQs

MCQs of Convection

Showing 31 to 40 out of 51 Questions

31.

The Prandtl number will be lowest for

(a)	water
(b)	liquid metal
(c)	aqueous solution
(d)	lube oil

32.

The value of Prandtl number for air is about

(a)	0.1
(b)	0.4
(c)	0.7
(d)	1.1

33.

Stanton number may be interpreted as the ratio of

(a)	temperature gradient at the surface to an overall or reference temperature gradient
(b)	buoyant to inertia force
(c)	heat transfer coefficient to the flow of heat per unit temperature rise due to the velocity of the fluid
(d)	heat conducted to the heat capacity

34.

Which dimensionless number has a significant role in forced convection?

(a)	Prandtl number
(b)	Reynolds number
(c)	Mech number
(d)	Peclet number

35.

For forced convection Nusselt number is a function of

(a)	Prandtl and Grashoff number
(b)	Reynolds and Prandtl number
(c)	Reynolds and Grashoff number
(d)	Reynolds number only

36.

Which one of the following non-dimensional numbers are used to determine the transition from laminar to turbulent flow in free convection?

(a)	Reynolds number
(b)	Grashoff number
(c)	Peclet number
(d)	Rayleigh number

37.

Consider fully developed laminar flow and heat transfer in a uniformly heated long circular tube If the flow velocity is doubled and the tube diameter is halved the heat transfer coefficient will become remain the original value

(a)	four times
(b)	double
(c)	half
(d)	same

38.

For laminar flow over a flat plate, the local heat transfer coefficient $h_{x}$ varies as $x \frac{- 1}{2}$ where x is the distance from the leading edge (x = 0) of the plate. The ratio of the average coefficient $h_{a v}$ between the leading edge and some location A at x=x on plate to the local heat transfer coefficient is

(a)	1
(b)	2
(c)	4
(d)	8

39.

The convective heat transfer co-efficient in the laminar flow over a flat plate

(a)	increases with distance
(b)	increases if a higher viscosity fluid is used
(c)	increases if a denser fluid is used
(d)	decreases with increases in a free stream velocity

40.

Peclet number is defined as

(a)	$\frac{k i n e m a t i c v i s \cos i t y}{t h e r m a l d i f f u s i v i t y}$
(b)	$\frac{c o n v e c t i v e h e a t t r a n s f e r}{c o n d u c t i o n h e a t t r a n s f e r}$
(c)	$\frac{b u o y a n c y f o r c e \times i n e r t i a l f o r c e}{v i s c o u s f o r c e}$
(d)	$\frac{w a l l h e a t t r a n s f e r r a t e}{c o n v e c t i o n h e a t t r a n s f e r}$

Showing 31 to 40 out of 51 Questions