- A. Decrease
- B. Increase
- C. Remain unchanged
- D. May increase or decrease; depends on the pressure
Heat Transfer
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At constant temperature, the thermal conductivities of gases _____ with rise in pressure.
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The unit of conductance in SI unit is_____.
- A. W/m
- B. W/m²
- C. W/°K
- D. W/m°K
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The unit of heat transfer co-efficient in SI unit is_____.
- A. J/m²°K
- B. W/m²°K
- C. W/m°K
- D. J/m°K
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LMTD correction factor which is to be applied for a cross-flow heat exchanger increases with increase in the number of shell passes. Its value for a single pass cross flow heat exchanger is_____.
- A. 0
- B. 1
- C. >1
- D. <1
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The actual temperature drop across the heating surface of an evaporator depends on the_____.
- A. Liquid depth over the heating surface
- B. Solution being evaporated
- C. Pressure difference between the steam chest and the vapor space above the boiling liquid
- D. All of the above
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The Grashoff number is defined as the ratio of the_____.
- A. Buoyancy to inertial forces
- B. Buoyancy to viscous forces
- C. Inertial to viscous forces
- D. Buoyancy to surface tension forces
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In case of heat flow by conduction for a cylindrical body with an internal heat source, the nature of temperature distribution is_____.
- A. Linear
- B. Hyperbolic
- C. Parabolic
- D. None of these
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Pick out the wrong statement.
- A. In drying a solid containing moisture above the critical moisture content the number of degrees of freedom is 2
- B. Sherwood number in mass transfer corresponds to Nusselt number in heat transfer and Schmidt number to Prandtl number
- C. Forced convection is relatively more effective in increasing the rate of mass transfer, if Schmidt number is larger
- D. Hot gases at moderate pressure are usually in the shell side of shell and tube heat exchangers. At higher pressure, however, it is customary to put gas in the tube side
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Heat flux through several resistances in series in analogous to the current flowing through several_____.
- A. Resistances in parallel
- B. Capacitors in series
- C. Resistances in series
- D. None of these
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The film co-efficient is decreased due to the presence of non-condensing gases in the vapors. The film co-efficient of superheated vapor as compared to that of saturated vapor is_____.
- A. More
- B. Less
- C. Some
- D. Either more or less ; depends on the nature of vapor