An air cooled cylindrical wall is to be fitted with triangular fins of 3 cm thickness at base and 12 cm in height. The fins are made from stainless steel with density 8000 kg/m3 and thermal conductivity 17.5 W/m K. The wall temperature is 600 degree Celsius and the fin is exposed to an environment with t a = 30 degree Celsius and h = 20 W/m2 K. What is the temperature distribution along the fin?

t = 40 + 250 I 0 [6.056 (x) 1/2].

t = 10 + 250 I 0 [6.056 (x) 1/2].

t = 20 + 250 I 0 [6.056 (x) 1/2].

t = 30 + 250 I 0 [6.056 (x) 1/2].

t = 40 + 250 I 0 [6.056 (x) 1/2].

Which one is true regarding parabolic fin?

It dissipates the minimum amount of heat at a minimum material cost

It dissipates the minimum amount of heat at a maximum material cost

It dissipates the maximum amount of heat at a maximum material cost

It dissipates the maximum amount of heat at a minimum material cost

Sometimes same or sometimes not same

1.	Consider the above problem, make calculations for the rate of heat flow per unit mass of fin material used
A.	126.53 W/kg
B.	154.76 W/kg
C.	134.87 W/kg
D.	165.46 W/kg
Answer» B. 154.76 W/kg

2.	An air cooled cylindrical wall is to be fitted with triangular fins of 3 cm thickness at base and 12 cm in height. The fins are made from stainless steel with density 8000 kg/m³ and thermal conductivity 17.5 W/m K. The wall temperature is 600 degree Celsius and the fin is exposed to an environment with t _a = 30 degree Celsius and h = 20 W/m² K. What is the temperature distribution along the fin?
A.	t = 10 + 250 I<sub> 0</sub> [6.056 (x)<sup> 1/2</sup>].
B.	t = 20 + 250 I<sub> 0</sub> [6.056 (x)<sup> 1/2</sup>].
C.	t = 30 + 250 I<sub> 0</sub> [6.056 (x)<sup> 1/2</sup>].
D.	t = 40 + 250 I<sub> 0</sub> [6.056 (x)<sup> 1/2</sup>].
Answer» D. t = 40 + 250 I<sub> 0</sub> [6.056 (x)<sup> 1/2</sup>].

3.	The heat dissipation at any section of parabolic fin is given by
A.	(t<sub>2</sub> t<sub>1</sub>) (b) ( )
B.	k (t<sub>2</sub> t<sub>1</sub>) (b) ( )
C.	k (t<sub>2</sub> t<sub>1</sub>) ( )
D.	k (t<sub>2</sub> t<sub>1</sub>) (b)
Answer» C. k (t<sub>2</sub> t<sub>1</sub>) ( )

4.	Provision of fins on a given heat transfer surface will be more effective if there is
A.	Fewer but thick fins
B.	Large number of thick fins
C.	Fewer but thin fins
D.	Large number of thin fins
Answer» E.

5.	The correction length for cylindrical fin is
A.	L <sub>C</sub> = L + d/4
B.	L <sub>C</sub> = 2 L + d/4
C.	L <sub>C</sub> = 3 L + d/4
D.	L <sub>C</sub> = 4 L + d/4
Answer» B. L <sub>C</sub> = 2 L + d/4

6.	For parabolic fin, the curve follows which law?
A.	y = C/x<sup>2</sup>
B.	y = C x<sup>4</sup>
C.	y = C x<sup>2</sup>
D.	y = C x<sup>1/2</sup>
Answer» D. y = C x<sup>1/2</sup>

7.	Which one is true regarding parabolic fin?
A.	It dissipates the minimum amount of heat at a minimum material cost
B.	It dissipates the minimum amount of heat at a maximum material cost
C.	It dissipates the maximum amount of heat at a maximum material cost
D.	It dissipates the maximum amount of heat at a minimum material cost
Answer» E.

8.	If a fin of a constant cross section is used, there would be wastage of material . Chose the correct option
A.	True
B.	False
Answer» B. False

9.	Heat dissipation by every segment of the fin is
A.	Sometimes same
B.	Same
C.	Not same
D.	Sometimes same or sometimes not same
Answer» D. Sometimes same or sometimes not same

10.	Which fin yields the maximum heat flow per unit weight?
A.	Straight triangular fin
B.	Curved triangular fin
C.	Parabolic fin
D.	Hyperbolic fin
Answer» B. Curved triangular fin