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Unit 06
1Q) What is Leidenfrost point? What are its significance?
2Q) Explain briefly the various regimes of saturated pool boiling. Or
What are different regimes of pool boiling? Explain with the help of a neat sketch. Or What are the different regimes of pool boiling? Explain where and why does radiation play a significant role in heat transfer during boiling.
3Q) Water at saturation temperature and atmospheric pressure is boiled in the stable film boiling regime with an electrically heated, horizontal platinum wire of diameter 1.27mm. Calculate the surface temperature necessary to produce a heat flux of 150kW/m2.
4Q) Estimate peak heat flux and minimum heat flux for water boiling at atmospheric pressure.
5Q) A heated 30cm*30cm square copper plate, serves as the bottom for a pan of water at 1 atm pressure. The temperature of the plate is maintained at 1190C. Estimate the heat transferred per hour by the plate.
6Q) Differentiate between the mechanism of film wise and drop wise condensation. Or
Distinguish between film wise and drop wise condensation. Which of the two gives a higher heat transfer coefficient? Why?
Unit 07
1Q) Give a comparison of parallel flow and counter flow heat exchangers. Why are counter flow heat exchangers mosly used?
2Q) Determine the overall heat transfer coefficient based on the outer area of a 3.81cm OD and 3.175cm ID brass tube (k=103.6w/mk) if the heat transfer coefficient for flow inside and outside the tube are 2270 and 2840w/m2k respectively and the unit fouling resistances at inside and outside are Rfi=Rfo=0.0088m2k/w
3Q) Derive an expression for logarithmic mean temp difference of the parallel flow heat exchanger. Or
Derive an expression for LMTD of a parallel flow heat exchanger. State the assumption you have made.
4Q) Derive an expression for LMTD for counter flow heat exchanger.
5Q) Define effectiveness of heat exchangers and obtain an expression for it in case of a parallel flow heat exchanger. Or
Derive an
1Q) What is Leidenfrost point? What are its significance?
2Q) Explain briefly the various regimes of saturated pool boiling. Or
What are different regimes of pool boiling? Explain with the help of a neat sketch. Or What are the different regimes of pool boiling? Explain where and why does radiation play a significant role in heat transfer during boiling.
3Q) Water at saturation temperature and atmospheric pressure is boiled in the stable film boiling regime with an electrically heated, horizontal platinum wire of diameter 1.27mm. Calculate the surface temperature necessary to produce a heat flux of 150kW/m2.
4Q) Estimate peak heat flux and minimum heat flux for water boiling at atmospheric pressure.
5Q) A heated 30cm*30cm square copper plate, serves as the bottom for a pan of water at 1 atm pressure. The temperature of the plate is maintained at 1190C. Estimate the heat transferred per hour by the plate.
6Q) Differentiate between the mechanism of film wise and drop wise condensation. Or
Distinguish between film wise and drop wise condensation. Which of the two gives a higher heat transfer coefficient? Why?
Unit 07
1Q) Give a comparison of parallel flow and counter flow heat exchangers. Why are counter flow heat exchangers mosly used?
2Q) Determine the overall heat transfer coefficient based on the outer area of a 3.81cm OD and 3.175cm ID brass tube (k=103.6w/mk) if the heat transfer coefficient for flow inside and outside the tube are 2270 and 2840w/m2k respectively and the unit fouling resistances at inside and outside are Rfi=Rfo=0.0088m2k/w
3Q) Derive an expression for logarithmic mean temp difference of the parallel flow heat exchanger. Or
Derive an expression for LMTD of a parallel flow heat exchanger. State the assumption you have made.
4Q) Derive an expression for LMTD for counter flow heat exchanger.
5Q) Define effectiveness of heat exchangers and obtain an expression for it in case of a parallel flow heat exchanger. Or
Derive an