Theory of Heat Transfer — Winter 2025

Define conduction, convection and radiation.

Discuss the important laws governing modes of heat transfer in real applications.

With a neat figure, derive the expression of general heat conduction equation in cartesian coordinates.

Give the applications of rectangular fins and circular fins in the field.

Define critical thickness of insulation and derive its expression for a cylinder.

Derive equation for temperature distribution and heat dissipation for fin insulated at the tip.

What is lumped capacitance method? When and in which applications it is used? Derive the expression of temperature distribution using it for a transient heat transfer.

Define convective heat transfer coefficient. On which factor it depends on?

Explain the development of thermal boundary layer over the hot flat plate.

Define Reynolds number, Nusselt number and Prandtl number. Explain their importance in convection heat transfer.

Derive the expression of conductive resistance and convective resistance for a one dimensional heat transfer through a plane wall.

Define fin efficiency and fin effectiveness?

Derive the expression of overall heat transfer coefficient for a composite cylindrical wall.

What is heat exchanger? Why it is used in heat transfer applications?

Explain the pros and cons of heat transfer in a co-current and countercurrent type of heat exchanger.

Using dimensional analysis, obtain a general form of Nusselt number for Natural Convective heat transfer.

What do you mean by fouling in heat exchangers?

Discuss filmwise and dropwise condensation with neat sketch.

Derive the expression of LMTD for a parallel flow heat exchanger.

What is radiation? Which are the factors affecting emission intensity of the body.

Define following: 1) Total emissive power 2) Emissivity1 3) Radiation intensity 4) Monochromotic Emissive Power

What is the Stephen-Boltzmann Law? Explain the concept of total emissive power of a surface.

Define Lambert’s law of radiation.

State and prove the Kirchoff’s law of radiation.

Define a shape factor. Derive its expression in case of radiation exchange between two surfaces.