Question 21 : Tubes are held between top and bottom tube sheets in Calenderia type evaporator by keeping
1. both the tube sheets fixed.
2. the top tube sheet fixed and the bottom tube-sheet floating.
3. both the tube sheets floating.
4. the top tube sheet floating and bottom tube sheet fixed.
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Question 22 : Fruit juice (a heat sensitive material) can be concentrated in a __________ evaporator.
1. falling film
2. long tube
3. high pressure
4. none of these
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Question 23 : With increase in temperature, the total emissivity of conductors
1. decreases
2. remains same
3. increases
4. decreases linearly
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Question 24 : In a heat exchanger, the rate of heat transfer from the hot fluid to the cold fluid
1. varies directly as the area and the LMTD.
2. varies as square of the area
3. directly proportional to LMTD and inversely proportional to the area.
4. none of these.
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Question 25 : Multiple effect evaporators ar used to
1. decrease the steam economy & the capacity.
2. increase the steam economy & the capacity.
3. increase the steam economy & decrease the capacity.
4. decrease the steam economy & increase the capacity.
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Question 26 : At constant temperature, the thermal conductivities of gases __________ with rise in pressure.
1. remain unchanged
2. decrease
3. increase
4. may increase or decrease; depends on the pressure
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Question 27 : Loss of heat from untagged steam pipe to the ambient air is by
1. conduction
2. radiation
3. convection
4. all of above
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Question 28 : Heat exchanger tubes are never made of
1. stainless steel
2. lead
3. copper
4. plain carbon steel
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Question 29 : Small scale evaporation is done in a
1. steam jacketed kettle
2. condenser
3. heat exchanger
4. multiple effect evaporator
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Question 30 : Calburn analogy is applicable for the value of Prandtl number from
1. 120 to 400
2. 0.001 to 1
3. 0.6 to 120
4. 0.5 to 5
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