Convective Heat Transfer(Heat Transfer ) Questions and Answers

Question 1. How many types of fluid flow are characterized in the realms of fluid mechanics?
  1.    1
  2.    2
  3.    3
  4.    4
Explanation:-
Answer: Option B. -> 2
Answer: (b).2

Question 2. In which fluid flow, the motion of fluid particles is irregular?
  1.    Turbulent
  2.    Laminar
  3.    One dimensional
  4.    Two dimensional
Explanation:-
Answer: Option A. -> Turbulent
Answer: (a).Turbulent

Question 3. Following are the characteristics of turbulent flow
(i) Eddying
(ii) Sinuous
(iii) Rectilinear
Identify the correct option
  1.    2 and 3
  2.    1 and 3
  3.    1, 2 and 3
  4.    1 and 2
Explanation:-
Answer: Option D. -> 1 and 2
Answer: (d).1 and 2

Question 4. The value of convective coefficient of air in case of free convection is
  1.    3-7 W/m² K
  2.    3-4 W/m² K
  3.    8-9 W/m² K
  4.    9-9.5 W/m² K
Explanation:-
Answer: Option A. -> 3-7 W/m² K
Answer: (a).3-7 W/m² K

Question 5. The nature of fluid flow is governed by following parameters
(i) Mean flow velocity
(ii) Density of fluid
(iii) Dynamic viscosity of the fluid
Identify the correct statements
  1.    1 and 3
  2.    1 only
  3.    1, 2 and 3
  4.    2 and 3
Explanation:-
Answer: Option C. -> 1, 2 and 3
Answer: (c).1, 2 and 3

Question 6. The oil pan of 1.6 engine approximates a flat plate 0.3 m wide by 0.45 m long and protrudes below the framework of the automobile. The engine oil is at 95 degree Celsius and the ambient air temperature is 35 degree Celsius. If the automobile runs at 36 km/hr, make calculations for the rate of heat transfer from the oil-pan surface. Assume negligible resistance to conduction through the oil pan
  1.    190.37 W
  2.    180.37 W
  3.    170.37 W
  4.    160.37 W
Explanation:-
Answer: Option C. -> 170.37 W
Answer: (c).170.37 W

Question 7. The ratio of inertia force to viscous force is known as
  1.    Grashof number
  2.    Reynolds number
  3.    Fourier number
  4.    Nusselt number
Explanation:-
Answer: Option B. -> Reynolds number
Answer: (b).Reynolds number

Question 8. Velocity within the given fields would be similar in magnitude, direction and turbulence pattern when
  1.    Nusselt number are different
  2.    Nusselt number are same
  3.    Reynolds number are different
  4.    Reynolds number are same
Explanation:-
Answer: Option D. -> Reynolds number are same
Answer: (d).Reynolds number are same

Question 9. Air flows through a 10 cm internal diameter tube at the rate of 75 kg/hr. Measurements indicate that at a particular point in the tube, the pressure and temperature of air are 1.5 bar and 325 K whilst the tube wall temperature is 375 K. Find heat transfer rate from one meter length in the region of this point
The general non-dimensional correlation for turbulent flow in the tube is
Nu = 0.023 (Re)^0.8 (Pr)^0.4
Where the fluid properties are evaluated at the bulk temperature
  1.    147.35 W
  2.    157.35 W
  3.    167.35 W
  4.    177.35 W
Explanation:-
Answer: Option D. -> 177.35 W
Answer: (d).177.35 W

Question 10. Reynolds number is given by the quantity
(Where,
p is density
δ is viscosity
V is volume
l is length)
  1.    p V l/δ
  2.    2 p V l/δ
  3.    3 p V l/δ
  4.    4 p V l/δ
Explanation:-
Answer: Option A. -> p V l/δ
Answer: (a).p V l/δ