B.TECH - Semester 6 heat and mass transfer Question Paper 2013 (apr)
Practice authentic previous year university questions for better exam preparation.
Sample Questions
- Define thermal conductivity and name the factors which affect thermal conductivity.
- Define critical radius of insulation and write the mathematical expression for the same in case of a hollow cylinder.
- What is the physical significance of Reynold's number?
- Name the different Non-dimensional parameters that come across in convection heat transfer.
- What is the difference between parallel flow and counter flow heat exchanger?
- Represent parallel flow and counter flow heat exchangers diagrammatically.
- Draw the boiling curve for water and show different regimes.
- What is a black body? What are its characteristics?
- State Kirchhoff's law.
- Explain fick's law of diffusion. (Answer any one full question from each Module; each carries 20 marks and each sub question carries 10 marks)
- (a) Derive an expression for steady state temperature distribution in a Cylinder with internal heat generation.
- (b) An exterior wall of a house may be approximated by a 0.1 m layer of common brick ( $\mathrm{k}=0.7 \mathrm{~W} / \mathrm{m}^{\circ} \mathrm{C}$ ) followed by a 0.06 m layer of gypsum plaster ( $\mathrm{k}=0.48 \mathrm{~W} / \mathrm{m}^{\circ} \ma...
- (a) Derive an expression for Steady, state temperature distribution in a slab with internal heat generation.
- (b) A steel pipe with 50 mm Outer diameter is covered with a 6.4 mm asbestos insulation ( $k=0.166 \mathrm{~W} / \mathrm{m}-\mathrm{k}$ ) followed by 25 mm layer of fiber glass insulation ( $\mathrm{k}=0.0485 \mathrm{~W} / \mathrm{m}-\mathrm{k}$ ) Th...
- (a) Air is flowing Over a flat plate of 5 m long and 2.5 m Wide with a velocity of $4 \mathrm{~m} / \mathrm{s}$ at $15^{\circ} \mathrm{C}$. If $\rho=1.208 \mathrm{~kg} / \mathrm{m}^{3}$ and kinematic Viscosity $=1.47 \times 10^{-5} \mathrm{~m}^{2} / ...
- (b) Show by Buckingham pi theorem that Nusselt number is a function of Reynold's number and Prandtl number in case of forced convection heat transfer.
- (a) The water is heated in a tank by dipping a plate ( $30 \mathrm{~cm} \times 30 \mathrm{~cm}$ ) size. The temperature of plate surface is maintained at $140^{\circ} \mathrm{C}$. Assuming the temperature of surrounding water at $20^{\circ} \mathrm{C...
- (b) In a Straight tube of 60 mm diameter water is flowing at a velocity of $12 \mathrm{~m} / \mathrm{s}$. the tube surface temperature is maintained at $70^{\circ} \mathrm{C}$ and the flowing water is heated from the inlet temperature $15^{\circ} \ma...
- (a) In a certain double pipe heat exchanger hot water flows at a rate of $50000 \mathrm{~kg} / \mathrm{h}$ and gets cooled from $95^{\circ} \mathrm{C}$ to $65^{\circ} \mathrm{C}$. at the same time $50000 \mathrm{~kg} / \mathrm{h}$ of cooling water at...
- (b) Derive an expression for LMTD in Parallel flow heat exchanger. OR
- (a) Write a note on Heat pipe.
- (b) Derive an expression for effectiveness in terms of NTU and heat capacity rates for parallel flow heat exchanger.
- (a) Derive an expression for radiation heat exchange $b / w$ two infinite gray parallel plates.
- (b) Calculate the net radiant heat exchange per $\mathrm{m}^{2}$ area for two large parallel plates at temperatures of $427^{\circ} \mathrm{C}$ and $27^{\circ} \mathrm{C}$ respectively. Emissivity (hot plate) $=0.9$ and $\varepsilon$ (cold plate) $=0...
- (a) A vessel contains a binary mixture of $\mathrm{O}_{2}$ and $\mathrm{N}_{2}$ with partial pressures in the ratio 0.21 and 0.79 at $15^{\circ} \mathrm{C}$. The total pressure of the mixture is 1.1 bar. Calculate the following (i) Molar concentratio...
- (b) Explain the analogy $A$ wheat and mass transfer. ( $4 \times 20=80$ Marks)