Theory of Heat Transfer — Winter 2022

State the fourier’s law of conduction with suitable example.

Derive expression for temperature distribution under 1D steady state heat conduction for composite cylinder.

Distinguish between conduction, convection and radiation modes of heat transfer with suitable examples.

What is Biot number? Write its significance.

What do you understand by fin effectiveness and fin efficiency?

Derive general heat conduction equation in Cartesian coordinates.

Using dimensional analysis, obtain a general form of equation for free Convective heat transfer.

Define: Thermal Boundary layer, Hydrodynamic Boundary layer.

Distinguish between natural and forced convection heat transfer.

What is the “critical radius” of insulation? Derive an expression for the same for cylinders.

State limitations of LMTD method.

Write down expression of effectiveness of following heat exchangers: (a) Parallel Flow (b) Counter flow (c) Condenser (d) Evaporator.

In a food processing plant, a brine solution is heated from -120C to -650C in double pipe parallel flow heat exchanger by water entering at 350C & leaving at 20.50C at the rate of 9 kg/min. Determine the heat exchanger area for an overall heat transfer coefficient of 850 W/m2K. For water C = p 4.186×103 J/kgK.

Define heat exchanger and classify in detail.

Write a note on Nucleate boiling?

Derive expression for logarithmic mean temperature difference (LMTD) in the case of counter-flow-heat exchanger.

Define condensation process.

What are the fouling factors? Explain their effect in Heat Exchanger design.

Derive a general relation for the radiation shape factor in case of radiation between two surfaces. Explain Wein’s displacement law of radiation.

State and Prove Kirchoff’s law of radiation?

Define: Total Emissive Power, Emissivity1

Apipe with a surface temperature of 480 Kis kept within a large enclosure whose walls are at 380 K. Presuming the pipe surface to be black, calculate the coefficient of radiant heat transfer. If the heat transfer coefficient including the effect of radiation and convection is 34.9 W/m2-deg, find the convective heat transfer coefficient.

Define: Black body, White body.

Differentiate between dropwise and filmwise condensation.

Define Radiation Intensity? Prove that the intensity of radiation is given by Ib = Eb / π .2