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Hassan
1.For the same type of shapes, the value of the radiation shape factor will be higher when?
A. Surfaces are closer
B. Surfaces are moved further apart
C. Surfaces are smaller and held closer
D. Surfaces are closer
2.The grey body shape factor for radiant heat exchange between a small body (emissivity = 0.4) in a large enclosure (emissivity = 0.5) is?
A. 0.1
B. 0.2
C. 0.4
D. 0.1
3.An enclosure consists of four surfaces 1, 2, 3 and 4. The view factors for radiation heat transfers are?
A. 0.50
B. 0.75
C. 0.1
D. 0.50
4.The value of shape factor depends on how many factors?
A. 1
B. 2
C. 3
D. 1
5.Which of the following is a wrong statement according to the shape factor is equal to one?
A. Inside cylinder to outer cylinder of a long co-axial cylinder
B. For a flat or convex surface with respect to itself
C. For infinite parallel planes radiating only to each other
D. Inside cylinder to outer cylinder of a long co-axial cylinder
6.Establish a relation for the shape factor of cylindrical cavity with respect to itself of depth h and diameter d. The cavity is closed on its outer surface with a flat plate?
A. h/4 h + d
B. 4 h + d/4 h
C. 4 h + d/h
D. h/4 h + d
7.The reciprocity theorem states that?
A. F 12 = F 21
B. A 1 F 12 = A 2 F 21
C. A 1 F 21 = A 2 F 12
D. F 12 = F 21
8.Two radiating surface A 1 = 6 m2 and A 2 = 4 m2 have shape factor F 12 = 0.1. Then the shape factor F 21 will be?
A. 0.10
B. 0.15
C. 0.18
D. 0.10
9.What is the value of shape factor for two infinite parallel surfaces separated by a distance x?
A. 0
B. 1
C. x
D. 0
10.What is the shape factor of a sphere of diameter d inside a cubical box of length l = d?
A. π/4
B. π/3
C. 2 π/6
D. π/4
11.What is the shape factor of hemispherical surface closed by a plane surface of diameter d?
A. 0.5
B. 1
C. 1.5
D. 0.5
12.What is the shape factor for a hemispherical bowl with respect to itself of diameter d? The cavity is closed on its outer surface with a flat plate?
A. 2.5
B. 0.5
C. 1
D. 2.5
13.Establish a relation for shape factor for a conical cavity with respect to itself of depth h and diameter d. The cavity is closed on its outer surface with a flat plate?
A. 1 – d/ (h 2 + d 2) 1/2
B. 1 – d/ (4 h + d 2) 1/2
C. 1 – d/ (4 h 2 + d 2) 1/2
D. 1 – d/ (h 2 + d 2) 1/2
14.Interchange factor for body 1 completely enclosed by body 2 (body 1 is large) is given by?
A. 3/ [1/E 1 + A1/A2 (1/E 2 – 1)].
B. 4/ [1/E 1 + A1/A2 (1/E 2 – 1)].
C. 1/ [1/E 1 + A1/A2 (1/E 2 – 1)].
D. 3/ [1/E 1 + A1/A2 (1/E 2 – 1)].
15.Interchange factor for infinitely long concentric cylinders is given by?
A. 1/ [1/E 1 + A1/A2 (1/E 2 – 1)].
B. 2/ [1/E 1 + A1/A2 (1/E 2 – 1)].
C. [1/E 1 + A1/A2 (1/E 2 – 1)].
D. 1/ [1/E 1 + A1/A2 (1/E 2 – 1)].
16.What is the geometric factor for infinitely long concentric cylinders?
A. 0.75
B. 0.33
C. 0.5
D. 0.75
17.What is the geometric factor for concentric spheres?
A. 0.95
B. 1
C. 0.33
D. 0.95
18.The net heat interchange between non-black bodies at temperature T 1 and T 2 is given by?
A. F 12 A 1 σ (T 14 – T 24)
B. f 12 A 1 σ (T 14 – T 24)
C. f 12 F 12 A 1 σ (T 14 – T 24)
D. F 12 A 1 σ (T 14 – T 24)
19.The total radiant energy leaving a surface per unit time per unit surface area is represented by?
A. Interchange factor
B. Irradiation
C. Radiosity
D. Interchange factor
20.Determine the radiant heat flux between two closely spaced, black parallel plates radiating only to each other if their temperatures are 850 K and 425 K. The plates have an area of 4 m2?
A. .010
B. .020
C. .030
D. .010
21.What is the value of grey body factor for concentric cylinders?
A. 2/ [1 – e 1/e 1 + 1 + 1 – e 2/e 2 (A 1/A 2)].
B. 1/ [1 – e 1/e 1 + 1 + 1 – e 2/e 2 (A 1/A 2)].
C. 4/ [1 – e 1/e 1 + 1 + 1 – e 2/e 2 (A 1/A 2)].
D. 2/ [1 – e 1/e 1 + 1 + 1 – e 2/e 2 (A 1/A 2)].
22.The net rate at which the radiation leaves the surface is given by?
A. e (E b – J)/1 – e
B. e (E b – J)/1 – 2 e
C. e (E b – J)/1 – 3 e
D. e (E b – J)/1 – e
23.Two opposed, parallel, infinite planes are maintained at 420 K and 480 K. Calculate the net heat flux between these planes if one has an emissivity of 0.8 and other an emissivity of 0.7?
A. 834.86 W/m2
B. 734.86 W/m2
C. 634.86 W/m2
D. 834.86 W/m2
24.Consider the above problem, if temperature difference is doubled by raising the temperature 480 K to 540 K, then how this heat flux will be affected?
A. 1503.55 W/m2
B. 1603.55 W/m2
C. 1703.55 W/m2
D. 1503.55 W/m2
25.The total radiant energy incident upon a surface per unit time per unit area is known as?
A. Irradiation
B. Radiation
C. Radiosity
D. Irradiation
26.Which one of the following is true for the opaque non-black surface?
A. J = ½ E + p G
B. J = 2 E + p G
C. J = E + p G
D. J = ½ E + p G
27.How many types of fluid flow are characterized in the realms of fluid mechanics?
A. 2
B. 4
C. 6
D. 2
28.In which fluid flow, the motion of fluid particles is irregular?
A. Two dimensional
B. One dimensional
C. Laminar
D. Two dimensional
29.The value of convective coefficient of air in case of free convection is?
A. 9-9.5 W/m2 K
B. 8-9 W/m2 K
C. 3-4 W/m2 K
D. 9-9.5 W/m2 K
30.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?
A. Laminar flow
B. Turbulent flow
C. Stream flow
D. Laminar flow
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