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Heat And Mass Transfer MCQ Questions & Answers | Mechanical Engineering

Learn Heat And Mass Transfer MCQ questions & answers are available for a Mechanical Engineering students to clear GATE exams, various technical interview, competitive examination, and another entrance exam. Heat And Mass Transfer MCQ question is the important chapter for a Mechanical Engineering and GATE students. Page-2 section-1

Each section contains 100 MCQs on Heat and Mass Transfer .
11
The value of Prandtl number for air is about
Discuss
Answer & Solution
Answer: Option C
Solution:
The value of Prandtl number for air is about 0.7
12
A steam pipe is to be insulated by two insulating materials put over each other. For best results
Discuss
Answer & Solution
Answer: Option A
Solution:
We should select a material which have low heat transfer capacity. So we should select a material which thermal conductivity is low. So that heat will pass through material is minimum. We should use low thermal conductivity material both side because after all we need to decrease the rate of heat transfer.
13
Total heat is the heat required to
Discuss
Answer & Solution
Answer: Option D
Solution:
Total Heat is the thermal equivalent of the energy required to convert unit mass of a liquid at one temperature (as the melting point of the substance) into saturated vapor at any other given temperature.
14
Sensible heat is the heat required to
Discuss
Answer & Solution
Answer: Option C
Solution:
Sensible heat is the energy required to change the temperature of a substance with no phase change. The temperature change can come from the absorption of sunlight by the soil or the air itself.
15
When heat is transferred from one particle of hot body to another by actual motion of the heated particles, it is referred to as heat transfer by
Discuss
Answer & Solution
Answer: Option A
Solution:
Conduction transfers heat via direct molecular collision. An area of greater kinetic energy will transfer thermal energy to an area with lower kinetic energy. Higher-speed particles will collide with slower speed particles. The slower-speed particles will increase in kinetic energy as a result.
16
When heat is transferred from hot body to cold body, in a straight line, without affecting the intervening medium, it is referred as heat transfer by
Discuss
Answer & Solution
Answer: Option C
Solution:
Thermal radiation generates from the emission of electromagnetic waves. These waves carry the energy away from the emitting object. Radiation occurs through a vacuum or any transparent medium (either solid or fluid). Thermal radiation is the direct result of random movements of atoms and molecules in matter.
17
The concept of overall coefficient of heat transfer is used in case of heat transfer by
Discuss
Answer & Solution
Answer: Option D
Solution:
It is used in calculating the heat transfer, typically by convection or phase transition between a fluid and a solid.
The heat transfer coefficient has SI units in watts per squared meter kelvin: $$\frac{{\text{W}}}{{{{\text{m}}^2}{\text{K}}}}$$ .
The heat transfer coefficient is the reciprocal of thermal insulance.
18
When heat is transferred by molecular collision, it is referred to as heat transfer by
Discuss
Answer & Solution
Answer: Option B
Solution:
Convection is the process of heat transfer by the bulk movement of molecules within fluids such as gases and liquids. The initial heat transfer between the object and the fluid takes place through conduction, but the bulk heat transfer happens due to the motion of the fluid
19
Stefan Boltzmann law is applicable for heat transfer by
Discuss
Answer & Solution
Answer: Option C
Solution:
Stefan-Boltzmann law is applicable for radiation it states that the total radiant heat power emitted from a surface is proportional to the fourth power of its absolute temperature. The law applies only to blackbodies, theoretical surfaces that absorb all incident heat radiation.
20
A non-dimensional number generally associated with natural convection heat transfer is
Discuss
Answer & Solution
Answer: Option A
Solution:
The Grashof number (Gr) is a dimensionless number in fluid dynamics and heat transfer which approximates the ratio of the buoyancy to the viscous force acting on a fluid. It frequently arises in the study of situations involving natural convection and is analogous to the Reynolds number.