Heat Transfer

51. Agitated film evaporator is suitable for concentrating _________ liquids.

1. Foaming
2. Viscous
3. Very thin
4. Corrosive

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52. Air is best heated with steam in a heat exchanger of

1. Plate type
2. Double pipe type with fin on steam side
3. Double pipe type with fin on air side
4. Shell and tube type

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53. Air is to be heated by condensing steam. Two heat exchangers are available (i) a shell and tube heat exchanger and (ii) a finned tube heat exchanger. Tube side heat transfer area are equal in both the cases. The recommended arrangement is

1. Finned tube heat exchanger with air inside and steam outside
2. Finned tube heat exchanger with air outside and steam inside
3. Shell and tube heat exchanger with air inside tubes and steam on shell side
4. Shell and tube heat exchanger with air on shell side and steam inside tubes

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54. All analogy equations connecting friction factor and heat transfer co-efficient apply only to

1. Wall or skin friction
2. Form friction
3. Both (A) and (B)
4. Turbulent flow

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55. Among liquids, water has a comparatively high value of thermal conductivity, due to its

1. Low density
2. High viscosity
3. Partial ionisation
4. Dense structure

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56. An ejector is used to

1. Increase pressure
2. Increase temperature
3. Remove condensate
4. None of these

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57. An equipment which converts the latent or sensible heat of one fluid into the latent heat of vaporisation of another, is called a

1. Boiler
2. Heat exchanger
3. Recuperator
4. Regenerator

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58. An evaporator while concentrating an aqueous solution from 10 to 40% solids evaporates 30000 kg of water. The amount of solids handled by the system in kg is

1. 4000
2. 9000
3. 4600
4. 3000

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59. Analogy between mass and heat transfer is not applicable in case of

1. Same velocity profile or equal eddy diffusivities
2. Thermal or pressure mass diffusion
3. Viscous heating or chemical reaction
4. Both (B) and (C)

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60. Arithmetic mean area can be used in heat transfer problem to calculate the heat flow by conduction through a cylinder which is

1. Thin walled having the value of A_o A_i/< 2
2. Thick walled
3. Having the value of A_o/A_i > 2
4. Both (B) and (C)

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