JNTU
JNTU B.Tech II INTRODUCTION TO TRANSPORT PHENOMENON Previous Question Paper (April/May - 2023 - R18)
Note: i) Question paper consists of Part A, Part B. ii) Part A is compulsory, which carries 25 marks. In Part A, Answer all questions. iii) In Part B, Answer any one question from each unit. Each question carries 10 marks and may have a, b as sub questions.
Part A
Identify the analogies between Newton’s law of viscosity and Fourier’s law of heat conduction.
Answer
Both laws describe transport processes driven by a gradient of a potential, where the flux is directly proportional to the gradient of a physical property. Newton's law of viscosity states that the momentum flux is proportional to the velocity gradient, expressed as τ = -μ(dv/dy), while Fourier's law of heat conduction states that the heat flux is proportional to the temperature gradient, expressed as q = -k(dT/dy). In both cases, the proportionality constant represents a transport property: viscosity (μ) for momentum transfer and thermal conductivity (k) for heat transfer.
State the mass balance equation in a control volume for a system without chemical reaction and with chemical reaction.
Answer
The mass balance equation is based on the principle of conservation of mass, which states that the rate of change of mass within a control volume is equal to the net rate of mass flow into the system plus the rate of mass generation.
For a system without chemical reaction, the rate of mass generation is zero. The equation is expressed as:
Where the left side represents the rate of accumulation of mass within the control volume and the right side represents the net rate of mass flux across the control surface.
For a system with chemical reaction, the rate of mass generation due to chemical species production must be included. The equation is expressed as:
Where R represents the net rate of mass generation per unit volume due to chemical reactions occurring within the control volume.
What is spherical coordinate system? List the basic variables used in this system.
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What are the commonly used boundary conditions for velocity distributions in laminar flow?
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What is friction factor chart? Mention the applications.
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Define Churchill and Chu correlation for natural convection heat transfer adjacent to vertical planes.
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Define unsteady heat transfer. List the variables affecting unsteady heat transfer rate.
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What are the differences between “thermal diffusivity” and “thermal conductivity” of a material?
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Determine the Schmidt number for methanol in air at 298 K and 1.013×105 Pa. At 298 K, the diffusivity of methanol in air is 1.62 × 10–5 m2/s and the kinematic viscosity of air is 1.569 × 10–5 m2/s.
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Define Sherwood number. Mention the physical significance.
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Part B
Explain the development of energy balance and mass balance equation using elemental volume approach.
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Discuss the effects of temperature and pressure on viscosity of liquids and gases.
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Derive the continuity equation applicable to unsteady, three-dimensional flow and when the flow is incompressible.
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Derive the “equation of motion” using momentum balance over the volume element in fluid flow field.
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Define exact solution for laminar flow problems.
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State and explain Hagen – poiseuille equation.
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Obtain an expression for the mass rate of flow ‘w’ for an ideal gas in laminar flow in a long circular tube. The flow is presumed to be isothermal. Assume that the pressure change through the tube is not very large, so that the viscosity can be regarded a constant throughout. Assume that the Hagen – Poiseuille equation can be applied over a small length ‘dz’ of the tube.
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Describe von – Karman friction factor correlation for turbulent flow in smooth tubes.
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State Darcy equation for the friction loss in pipe flow.
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State Stefan – Boltzmann law for non – black surface.
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Consider a composite plane wall constructed of three materials in layers (series). Derive expression for the steady-state heat transfer rate per unit area across the wall between a hot gas at temperature (Th) on one side of wall and a cool gas at temperature (Tc) on the other side.
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Explain Reynolds analogy for relating the rate of energy transfer and momentum transfer.
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Discuss the importance of Stanton number and Chilton – Colbum j – factor in heat transfer.
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Discuss the Prandtl analogy for convective heat transfer under turbulent flow conditions.
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Write the expression of heat flux for heat flow through a hollow cylinder with inner radius (ri), outer radius (ro) and length (L). Define log mean radius for this system.
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Explain the concentration gradients for equimolal and unicomponent diffusion of components A and B diffusing at same molal rates in opposite directions.
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What are the effects of temperature and pressure on molecular diffusion?
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Consider the process of “diffusion with a heterogeneous chemical reaction” system having the stoichiometry 2A → B (gas). This reaction occurs at the spherical catalyst surface. Derive an expression for molar flux (NAZ) of gas reactant ‘A’ through the gas film.
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