0% 0 Chemical Heat Transfer Quiz 5 1 / 50 In case of a shell and tube heat exchanger, the minimum and maximum baffle spacing is respectively (where, D = inside diameter of the shell) ? D and 2 D D/4 and 2 D D/2 and 2 D D/5 and D 2 / 50 In case of parallel flow heat exchanger, the lowest temperature theoretically attainable by the hot fluid is ______ the outlet temperature of the cold fluid? Either more or less than (depending upon the fluid) Less than More than Equal to 3 / 50 Leidenfrost point is a term concerned with the______? Boiling of a liquid on a hot surface Condensation of the saturated vapor on a cold surface Heat transfer between two highly viscous liquids Concentration of a corrosive solution by evaporation 4 / 50 In which mode of heat transfer, the Biot number is important ? Natural convection Radiation Forced convection Transient heat conduction 5 / 50 In case of evaporators, liquid entrainment results primarily due to__________? High heat transfer rate High vacuum in the evaporator High evaporation rate Foaming of the solution 6 / 50 jH factor for heat transfer depends upon the _____ number? Nusselt Biot Prandtl Reynolds 7 / 50 LMTD for evaporators & condensers for a given terminal parameters & set of conditions for counter-flow is equal to that for parallel flow. In such heat exchangers, with one of the fluids condensing or evaporating, the surface area required is the least in the _______ flow? Same in either A , B. or C. Parallel Counter flow Mixed 8 / 50 In case of surface condensers, a straight line is obtained on plotting 1/U vs. _____ on an ordinary graph paper? V? -0.8 1/ V? -2 1/V? -0.8 V? -2 9 / 50 LMTD can?t be used as such without a correction factor for the__________? Multipass heat exchanger All A. B. and C. Baffled heat exchanger Condensation of mixed vapour in a condenser 10 / 50 In forced convection, the Nusselt number is a function of ______? Re and Pr Re and Sc Re and Gr Pr and Gr 11 / 50 In natural convection heat transfer, the correlating parameter is the_________? Grashoff number Eckert number Bond number Graetz number 12 / 50 Log mean temperature difference (LMTD) cannot be used, if _____? The heat capacity is not constant and there is a phase change There exists an unsteady state None of these Heat transfer co-efficient over the entire heat exchanger is not constant 13 / 50 In SI units, thermal conductivity is expressed in___________? Watt/m4. ?K Watt/m2. ?K Watt/m.?K Watt/m2. ?K 14 / 50 Intermittent tube cleaning is possible to be done in case of a ______ evaporator? Calandria None of these Horizontal tube Basket type 15 / 50 It is not preferable to use superheated steam in evaporators, because of its very__________? None of these High pressure High temperature Low film co-efficient 16 / 50 It is not recommended to use a 1-2 shell and tube heat exchanger for a particular heat duty, whenever the LMTD correction factor is_____? < 0.25 < 0.75 < 0.50 > 0.75 17 / 50 Low thermal conductivity of heat insulating materials is due to its________? Dense structure None of these High specific heat High proportion of air space 18 / 50 Kirchoff?s law is applicable to_________? Both A. and B. Monochromatic radiation only Only volumes and not to surfaces Total radiation only 19 / 50 In evaporators, lowering the feed temperature________? Increases the heating area required Reduces the economy Both A. and B. Decreases the heating area required 20 / 50 Indirect contact heat exchangers are preferred over direct contact heat exchangers, because__________? Cost of equipment is lower There is no risk of contamination Heat transfer co-efficient are high There is no mist formation 21 / 50 In forced circulation, the heating element is injected__________? Internally Externally Both A. and A. Neither A. nor B. 22 / 50 Kirchoff?s law applies to ______ radiation? Both A. & B. Total Neither A. nor B. Monochromatic 23 / 50 jH factor for heat transfer is not a function of the ________ number? Reynolds Grashoff Both B. & C. Nusselt 24 / 50 Kg of liquid evaporated per hour in an evaporator is defined as its__________? Economy None of these Steam load Capacity 25 / 50 In SI units, fouling factor is expressed in ___________? m?K/W m2?K m2?K/W W/m2?K 26 / 50 Loss of heat from untagged steam pipe to the ambient air is by ___________? Radiation All A., B. & C. Conduction Convection 27 / 50 LMTD for counter-flow and parallel flow heat exchanger will be the same, when the__________? Outlet temperature of both the hot and cold fluid are same Outlet temperature of hot fluid is less than the outlet temperature of the cold fluid Cold fluid is heated to a certain temperature by condensing steam (isothermal fluid) None of these 28 / 50 In case of a vertical tube evaporator, with increase in the liquor level, the _____ is increased? Neither A. and B. Liquor-film co-efficient Velocity of circulation Both A. and B. 29 / 50 In case of a multipass shell and tube heat exchanger, providing a baffle on the shell side _______ the heat transfer rate? Increases Does not affect May increase or decrease, depends on the type of baffle Decreases 30 / 50 In pipe flow, heat is transferred from hot wall to the liquid by___________? Conduction only Free and forced convection Forced convection only Forced convection and conduction 31 / 50 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 ___________? > 1 0 < 1 1 32 / 50 In Fourier?s law, the proportionality constant is called the________? Thermal diffusivity Heat transfer co-efficient Stefan-Boltzmann constant Thermal conductivity 33 / 50 In counter flow compared to parallel flow, ? Less surface area is required for a given heat transfer rate LMTD is greater More surface area is required for a given heat transfer rate Both A. and B. 34 / 50 In case of a multipass shell and tube heat exchanger, the temperature drop in the fluid ________? None of these And the wall are proportional to individual resistances And the wall is not related Is inversely proportional to the resistance across which the drop occurs 35 / 50 In the equation Q = UA?t; ?t is___________? Arithmetic mean temperature difference Logarithmic mean temperature difference The difference of average bulk temperatures of hot and cold fluids Geometric mean temperature difference 36 / 50 In case of vertical tube evaporator, with increase in liquor level, the overall heat transfer co-efficient_______? Increases May increase or decrease; depends on the feed Decreases Is not affected 37 / 50 Maximum water velocity in tubes of a 1-2 shell and tube heat exchanger may be around ______ metres/second? 20 30 1 10 38 / 50 In case of heat transfer by conduction in a hollow cylinder, _______ mean area is used to calculate the heat transfer rate? Logarithmic Geometric Arithmetic Either A., B. or C. 39 / 50 Latent heat absorbed by 1 lb of water at 212?F, when it is changed to steam at 212?F, may be around _______ BTU? 970 None of these 3.97 180 40 / 50 Increasing the liquor level in the evaporator results in the________? Increase in liquor film co-efficient Decreased capacity Increased true temperature drop Decreased effect of hydrostatic head 41 / 50 Maximum heat transfer rate can be expected in case of_________? Co-current flow Turbulent flow Laminar flow Heat flow rate is independent of nature of flow Submitted by:?Faheem Zaman Dhaunroo 42 / 50 In the free convection regime of pool boiling, the heat flux is proportional to___________? ?t5/4 ?t ?t1/2 ?t2 43 / 50 In case of a vertical tube evaporator, with increase in the liquor level, the_____? Capacity of the evaporator is increased Capacity of the evaporator is decreased Both B. and C. True temperature drop increases 44 / 50 In case of heat flow by conduction for a cylindrical body with an internal heat source, the nature of temperature distribution is__________? Linear None of these Hyperbolic Parabolic 45 / 50 Low thermal conductivity of heat insulating materials is due to its__________? Dense structure High proportion of air space None of these High specific heat 46 / 50 Maximum heat transfer rate is obtained in _______ flow? Creeping Laminar Transition region Turbulent 47 / 50 In sub-cooled boiling ? Temperature of the heating surface is less than the boiling point of the liquid Bubbles from heating surface are absorbed by the mass of the liquid Very large vapour space is necessary Temperature of the heating surface is more than the boiling point of the liquid 48 / 50 In case of a super-cooled solution, which is on the verge of crystallisation, the free energy of the solution as compared to that of the solid is _________? More Less Same More or less; depends on the nature of solution 49 / 50 Maximum heat transfer rate is achieved in ______ flow? Co-current Turbulent Laminar Counter-current 50 / 50 In regenerative air preheater (as practised in heating of coke ovens), the heat is transferred__________? Through a metallic wall By direct contact of hot flue gas with air By heating an intermediate material (like chequor bricks) and then heating the air from this hot material None of these Provide Your Information Your score is The average score is 0% LinkedIn Facebook Twitter 0% Restart quiz Send feedback Share on facebook Facebook Share on twitter Twitter Share on whatsapp WhatsApp PrevChemical Heat Transfer Quiz 4 Chemical Heat Transfer Quiz 6Next
