Name of the College : Karunya Institute of Technology & Sciences
University : Kaunya University
Degree : B.Tech
Department : Mechanical Engineering
Subject Code/Name : 09ME204 Heat & Mass Transfer
Document Type : Model Question Paper
Website : karunya.edu
Download :https://www.pdfquestion.in/uploads/ka…07-09ME204.pdf
Kaunya Heat & Mass Transfer Question Paper
Part – A
(10 x 1 = 10 Marks) :
1. Give the equation for Fourier law of conduction.
2. Define overall heat transfer co-efficient.
3. What is meant by Semi-infinite solids?
Related : Karunya University 12CE263 Fluid Mechanics & Machinery B.Tech Model Question Paper : www.pdfquestion.in/2915.html
4. Define Biot number.
5. Define term effectiveness for a fin?
6. What is free convection?
7. List the classification of heat exchangers based on flow direction.
8. Define Stephen’s Law.
9. Mention a few industrial applications where boiling and condensation are important.
10. Define shape factor.
Part – B
(5 x 3 = 15 Marks) :
11. A brick wall (k = 0.7 W/moC) is 0.3 m thick. Inner surface is maintained at 45oC and outside surface, at 25oC. Calculate the heat transfer rate per m2 of area. Also find the temperature at the mid-plane.
12. A hot plate 35 cm high and 1.1 m wide at 160oC is exposed to ambient air at 20oC. Calculate the boundary layer thickness at 10 cm from the leading edge of the plate.
13. What is overall heat transfer coefficient? What is its importance?
14. The flow rates of hot and cold water streams running through parallel flow heat exchangers are 0.2 kg/s and 0.5 kg/s respectively. The inlet temperatures on the hot and cold sides are 75oC and 20oC respectively. The exit temperature of hot water is 45oC. Find outlet temperature of cold streams and Logarithmic mean temperature difference.
15. Emissivities of two large parallel planes maintained at 800 ?C and 300 ?C are 0.3 and 0.5 respectively. Find the net radiant heat exchange per square metre for these plates?
Part – C
(5 x 15 = 75 Marks) :
16. Derive the heat conduction equation in cylindrical coordinates.
(OR)
17. A steel pipe line (k=50W/mK) of ID 100mm and OD 110mm is to be covered with two layers of insulation each having a thickness of 50mm. The thermal conductivity of the first insulation material is 0.06 W/mK and that of the second is 0.12 W/mK. Calculate the loss of heat per meter length of pipe and the interface temperatures between the two layers of insulation when the temperature of the inside tube surface is 250 º C and that of the outside surface of the insulation is 50 º C.
18. An iron sphere of diameter 5 cm is initially at a uniform temperature of 225oC. It is suddenly exposed to an ambient at 25oC with convection coefficient of 500 W/m2 oK.
a. Calculate the centre temperature 2 minute after the start of exposure.
b. Calculate the temperature at the depth of 1 cm from the surface after 2 minute of exposure.
c. Calculate the energy removed from the sphere during this period. Take properties of iron plate K = 60 W/moK, ? = 7850 kg/m3, C = 460 J/kg, a = 1.6 x 10-5 m2/s.
(OR)
19. An Aluminium sphere weighting 6 kg and initially at temperature of 350oC is suddenly immersed in a fluid at 30oC with convection coefficient of 60 W/m2 oC. Estimate the time required to cool the sphere to 100oC. Take thermo physical properties as C = 900 J/KgoK, ? = 2700 kg/m3 and k = 205 W/moK.
20. A 30cm long glass plate is hung vertically in the air at 27 º C while its temperature is maintained at 77 º C. Calculate the boundary layer thickness at the trailing edge of the plate. If a similar plate is placed in a wind tunnel and air is blown over it at a velocity of 4 m/s, estimate the boundary layer thickness at its trailing edge.
(OR)
21. A hot square plate 50 cm x 50 cm at 1000C is exposed to atmospheric air at 200C.Find the Heat loss from both surfaces of the plate if (i) The plate is kept in vertical plane and (ii)A plate is kept in horizontal plane. Determine the percentage heat loss if the plate is kept horizontal instead of vertical
22. In a counter flow double pipe heat exchanger, oil is cooled from 850C to 550 C by water entering at 250 C. the mass flow rate of oil is 9,800kg/h and specific heat of water is 4180 J/kg K. Determine the heat exchanger area and heat transfer rate for an overall heat transfer co-efficient of 280 W/m2K.
(OR)
23. Co2 and air experience equimolar counter diffusion in circular tube whose length and diameter are 1m and 50mm respectively. The system is at a total pressure of 1 atmosphere and a temperature of 250C.The ends of the tube are connected to large chambers in which the species concentration are maintain a fixed values. The partial pressure of Co2at one end is 190 mm of Hg while other end is 95mm of Hg. Estimate the mass transfer rate of Co2 and the air through the tube.
24. A pipe carrying steam having an outside diameter of 20 cm runs in a large room and is exposed to air at a temperature of 30°C. The pipe surface temperature is 400°C. Calculate the loss of heat to surroundings per meter length of pipe due to thermal radiation. The emissivity of pipe surface is 0.8. What would be the loss of heat due to radiation if the pipe is enclosed in a 40cm diameter brick conduit of emissivity 0.91?
(OR)
25. Discuss briefly the various regimes in pool boiling heat transfer with a neat sketch.