26. With the increase of temperature, the Col-burn jH factor
27. In case of evaporators, liquid entrainment results primarily due to
28. Baffles in the shell side of a shell and tube heat exchanger
29. 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
30. The unit of heat transfer co-efficient in SI unit is
31. The number of kg vaporised per kg of steam fed to the evaporator is defined as
32. Economy of a multiple effect evaporator is not influenced much by the
33. Increasing the liquor level in the evaporator results in the
34. The equivalent diameter for pressure drop is __________ that for heat transfer.
35. Controlling heat transfer film co-efficient is the one, which offers __________ resistance to heat transfer.
36. The heat flux (from outside to inside) across an insulating wall with thermal conductivity, K= 0.04 W/m.°K and thickness 0.16m is 10 W/m2. The temperature of the inside wall is - 5°C. The outside wall temperature is
37. Thermal conductivity of a conducting solid material depends upon its
38. The average heat transfer co-efficient for laminar film condensation on vertical surface is inversely proportional to (where, ΔT = Temperature drop across condensate film )
39. Bulk of the convective heat transfer resistance from a hot tube surface to the fluid flowing in it, is
40. Which of the following is concerned with both heat and mass transfer ?
41. A backward feed multiple effect evaporator is better than forward feed for concentrating cold feed, because it provides
42. A 10 cm dia steam pipe, carrying steam at 180°C, is covered with an insulation (conductivity = 0.6 W/m.°C). It losses heat to the surroundings at 30°C. Assume a heat transfer co-efficient of 0.8 W/m2.°C for heat transfer from surface to the surroundings. Neglect wall resistance of the pipe and film resistance of steam. If the insulation thickness is 2 cms, the rate of heat loss from this insulated pipe will be
43. Which area is used in case of heat flow by conduction through a cylinder ?
44. Heat transfer by conduction results due to the transfer of free electrons, kinetic energy & vibrational energy from one molecule to another. Conduction heat transfer can not take place
45. The dimensionless group in mass transfer that is equivalent to Prandtl number in heat transfer is
46. Finned tube heat exchangers
47. The absorptivity of a grey body at a given temperature __________ with increasing wavelength of radiation.
48. Which one gives the monochromatic emissive power for black body radiation ?