Heat Transfer MCQ’s – Shape Factor
1 - Question
“All the factors relating to the geometry of the sections are grouped together into a multiple constant called the shape factor”.
Explanation: They are grouped together into a single constant instead of multiple one.
2 - Question
Shape factor for a plane wall is equal to
Explanation: It should be obtained by dividing area with respect to length.
3 - Question
For a prescribed temperature difference, bodies with the same shape factor will allow heat conduction proportional to
Explanation: It is proportional to material thermal conductivity irrespective of size and configuration.
4 - Question
Shape factor for cylinder is
a) 6 π l/log e (r 2/r 1)
b) 4 π l/log e (r 2/r 1)
c) π l/log e (r 2/r 1)
d) 2 π l/log e (r 2/r 1)
Explanation: It is two times the rest of the product.
5 - Question
The annealing furnace for continuous bar stock is open at the ends and has interior dimensions of 0.6 m * 0.6 m * 1.5 m long with a wall 0.3 m thick all around. Calculate the shape factor for the furnace?
a) 15.24 m
b) 16.34 m
c) 14.54 m
d) 13.76 m
Explanation: Shape factor for 4 walls = 4 (area of wall)/ (thickness) = 4 (1.5) (0.6)/0.3 = 12 m. Shape factor for 4 edges = 4 (0.54) (1.5) = 3.24 m. Total = 15.24 m.
6 - Question
Shape factor for sphere is
a) 4 π r 1 r 2
b) 4 π r 1 r 2/r 2 – r 1
c) 4 π /r 2 – r 1
d) r 1 r 2/r 2 – r 1
Explanation: In case of sphere it is given in option b. Area of sphere is 4 π r 2.
7 - Question
Which is true regarding a complete rectangular furnace?
a) 6 walls, 12 edges and 6 corners
b) 0 walls, 2 edges and 4 corners
c) 6 walls, 12 edges and 8 corners
d) 2 walls, 6 edges and 8 corners
Explanation: It has 6 walls, 12 edges and 8 corners.
8 - Question
The shape factor for complete rectangular furnace is Where a, b and c are the inside dimensions and d x is the wall thickness
a) 2/ d x (a b + b c + c a) + 4 (0.64) (a + b +c) + 8 (0.45) d x
b) 2/ d x (a b + b c + c a) + 4 (0.44) (a + b +c) + 8 (0.35) d x
c) 2/ d x (a b + b c + c a) + 4 (0.34) (a + b +c) + 8 (0.25) d x
d) 2/ d x (a b + b c + c a) + 4 (0.54) (a + b +c) + 8 (0.15) d x
Explanation: S edge = 0.54 times length of edge. S corner = 0.15 d x.
9 - Question
For the same material and same temperature difference, the heat flow in terms of shape factor is given by
a) S k d t
b) k d t/S
c) 2S k/d t
Explanation: The heat flow is proportional to the shape factor.
10 - Question
For the same amount of fabrication material and same inside capacity, the heat loss is lowest in
Explanation: For cylinder, it is 0.439 i.e. lowest.