Question Paper: Heat Transfer Operation - 2 Question Paper - May 2016 - Chemical Engineering (Semester 6) - Mumbai University (MU)
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Heat Transfer Operation - 2 - May 2016

MU Chemical Engineering (Semester 6)

Total marks: --
Total time: --
INSTRUCTIONS
(1) Assume appropriate data and state your reasons
(2) Marks are given to the right of every question
(3) Draw neat diagrams wherever necessary
1(a) How do noncondensables affects condenser operation? 5 marks

1(b) List gasket materials used in plate heat exchanger with their respective applications 5 marks

1(c) What , if fouling is not considered while exchanger design? 5 marks

1(d) Explain the working of kettle type reboiler with neat sketch. 5 marks

2 There is a requirement to cool 160,000 Kg/hr of a ethanol from 70°C to 30°C. Cooling water will be used for cooling, with inlet and outlet temperature of 20°C and 60°C. Design a gasketed-plate heat exchanger for this duty with stainless steel(k=15 W/mK) Plates of 0.5mm thick. Maximum operating pressure and allowable pressure for both fluids is 2 bar and 0.6 bar respectively and maximum permissible velocity is 3 m/s. Show one iteration of design calculation including thermal and hydrodynamic and if design is not satisfactory in lirst iteration then comment on the calculations?
Data:

  Property Cooling water Ethanol
  Specific heat, KJ/Kg.k 4.179 2.46
  Viscosity, cP 0.705 0.67
  Thermal conductivity, /m.k 0.62 0.171
  Density, Kg/m3 995 772
5 marks

3(a) Explain working of horizontal reboiler with schematic sketch. 5 marks

3(b) Explain operation of barometric condenser. 5 marks

4(a) What are the factors to be considered for allocation of fluid in shell or tube? 5 marks

4(b) Explain use of sealing strips in shell and tube exchanger. 5 marks

4(c) How do overdesign influence operation of heat exchanger like condenser, reboiler and coolers? 5 marks

5 A shell and tube heat exchanger has the following configration:
The shell side fluid is a hot water (mass flow = 7500 kg/hr) with the following properties:

  Specific heat, kcal/Kg.K   4.3706
  Thermal conductivity, W/m.K   0.5787
  Viscosity, cP   0.3307
  Specific gravity   0.9673

Using Bell-Delaware method, calculate the shell side heat transfer coefficient for following data.
  Number of tubes   34
  Shell Inner Diameter   279.401 mm
  Bundle diameter   254.88 mm
  Tube outer diameter   25.4 mm
  Sealine strips   None
  Pitch 1.25Δ   31.75 mm
  No. of baffles   35
  Baffle spacing (centre to centre)   75 mm
  Baffle cut   24.48%
5 marks

6(a) 9150 kg/hr of saturated cyclohexane vapour will be condensed at 83.33°C and 1.1.0 bar using a tube bundle containing 147 tubes arranged for single pass. The tubes are 1 inch. Outer diameter 14 B WG thickness with a length of 6096 mm. Calculate the condensing side coefficient for the tube bundle is condense with condensation over tube, and comment on result.
Data:

  Density of condensate, kg/m3   791.0
  Viscosity, cP   0.3311
  thermal conductivity, W/m.K   0.1512
  Specific heat, KJ/kg.K   2.1562
5 marks

6(b) Explain operation of reflux condenser. 5 marks

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