Chemical Heat Transfer MCQs Competitive – Chemical Engineering MCQs
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Latest Chemical Engineering MCQs
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Latest Chemical Heat Transfer Mcqs
The most occurred mcqs of Chemical Heat Transfer in past papers. Past papers of Chemical Heat Transfer Mcqs. Past papers of Chemical Heat Transfer Mcqs . Mcqs are the necessary part of any competitive / job related exams. The Mcqs having specific numbers in any written test. It is therefore everyone have to learn / remember the related Chemical Heat Transfer Mcqs. The Important series of Chemical Heat Transfer Mcqs are given below:
A long iron rod initially at a temperature of 20°C has one end dipped in boiling water (100°C) at time, t = 0. The curved surface of the rod is insulated so that heat conduction is one dimensional in the axial direction. The temperature at a distance 100 mm from the dipped end becomes 40°C at time, t = 200 s. The same temperature is achieved at a distance of 200 mm from the dipped end at time ___________________?
A. t = 356 s
B. t = 283 s
C. t = 400 s
D. t = 800 s
For specified tube outside diameter, higher BWG means higher___________________?
A. Weight per unit length
B. Cross-sectional area
C. Tube thickness
D. None of these
Unsteady state heat conduction occurs, when_______________?
A. Heat flows in one direction only
B. Temperature distribution is dependent on time
C. Temperature distribution is independent of time
D. Three dimensional heat flow is concerned
_____________ equation relates the thermal conductivity of a solid to its temperature ?
A. Kopp’s
B. Antoine
C. Lee’s
D. Kistyakowsky
The purpose of providing bleed points in the evaporator is to__________________?
A. Remove the product
B. Admit the feed
C. Facilitate removal of non-condensable gases
D. Create vacuum
Rate of heat transfer by vaporisation from pools of water is affected by the ____________________?
A. Nature of heating surface and distribution of bubbles
B. Viscosity of water
C. Surface tension of water
D. All A., B. and C.
Prandtl number is the ratio of________________?
A. Thermal diffusivity to mass diffusivity
B. Momentum diffusivity to thermal diffusivity
C. Mass diffusivity to thermal diffusivity
D. Thermal diffusivity to momentum diffusivity
A hot body will radiate heat most rapidly, if its surface is___________________?
A. White & polished
B. Black & rough
C. White & rough
D. Black & polished
Chemical Reaction Mcqs
A hot liquid is kept in a big room. The logarithm of the numerical value of the temperature difference between the liquid and the room is plotted against time. The plot will be very nearly a/an___________________?
A. Parabola
B. Straight line
C. Ellipse
D. Circular arc
Which is the most suitable for the concert-ration of highly concentrated solution ?
A. Open pan evaporation
B. Agitated film evaporator
C. Long tube vertical evaporator
D. None of these
Heat transfer efficiency leading of energy conservation in a heat exchanger can be achieved by____________________?
A. Keeping the heat transfer surface clean
B. Increasing the tube length
C. Enhancing the fluid pumping rate
D. None of these
A measure of the extent to which viscous heating is important relative to the heat flow resulting from the impressed temperature difference is represented by the _______________ number?
A. Grashoff
B. Condensation
C. Stanton
D. Brinkman
If a single tube pass heat exchanger is converted to two pass, then for the same flow rate, the pressure drop per unit length in tube side will ________________?
A. Decrease by 22
B. Increase by 1.8 times
C. Increase by 216
D. Remain unchanged
The rate of heat transfer through a pipe wall is given by, q = 2π k (Ti – T0)/ln (ri/r0). For cylinder of very thin wall, q can be approximated by__________________?
A. q = [2π k (Ti + T0)/2]/ln (ri/r0)
B. q = 2π k (Ti – T0)/(r0/ri)
C. q = 2π ri k (Ti – T0)/(r0/ri)
D. q = 2π k (Ti – T0)/[(r0 + ri)/2]
Prandtl and Reynold’s analogies are identical for Prandtl number value of__________________?
A. 0.5
B. 0
C. 1
D. 5
Baffles are provided in heat exchangers to increase the________________?
A. Heat transfer area
B. Fouling factor
C. Heat transfer co-efficient
D. Heat transfer rate
_______________ paint has the maximum absorption coefficient ?
A. Black
B. White
C. Yellow
D. Grey
Steam condensate is recovered by steam traps and recycled for use as boiler feed water, because of its low___________________?
A. Dissolved solids content
B. Hardness
C. Suspended solids content
D. All A., B. and C.
Crystallisation of solids from a homogeneous solution is a/an ______________ process?
A. Exothermic
B. Highly endothermic
C. Mildly endothermic
D. None of these
Absorptivity of a perfect black body is unity. Which of the following has maximum absorptivity ?
A. Refractory bricks
B. Aluminium foil
C. Iron plate
D. Coke breeze
The energy radiated from a surface Q at absolute temperature T is related as__________________?
A. Q ∝ T3
B. Q ∝ T4
C. Q ∝ T2
D. None of these
Removal of ______________ heat is involved in the condensation of a vapor under saturated conditions?
A. Latent
B. Sensible
C. Super
D. Both B. & C.
The purpose of providing a ‘catchall’ in the vapor line of an evaporator is to__________________?
A. Regulate the vapor flow
B. Create vacuum
C. Vent the non-condensable gases
D. Arrest the entrained liquid
Thermal conductivities of most of the liquids _______________ with rise in temperature?
A. Remains unchanged
B. Decreases
C. Increases
D. May increase or decrease; depends on the liquid
Evaporation of 1kg of water from a solution in a single effect evaporator requires about ________________ kg of steam?
A. 1.8-2
B. 1-1.3
C. 0.4 – 0.6
D. 2 – 2.4
_____________ heat exchanger is the most suitable, when the temperature of shell side fluid is much higher than that of tube side?
A. Three pass, fixed tube sheet
B. U-tube
C. Single pass, fixed tube sheet
D. None of these
Heat transfer in the laminar sub-layer in case of a liquid flowing through a pipe, is mostly by__________________?
A. Convection
B. Conduction
C. Eddies current
D. None of these
Chemical Engineering Basics Mcqs
For condensation of pure vapors, if the heat transfer co-efficients in filmwise and drop-wise condensation are respectively hf and hd, then__________________?
A. hf > hd
B. hf = hd
C. hf < hd
D. hf could be greater or smaller than hd
Which of the following forced convection heat transfer equation accounts for the liquid viscosity effect for viscous liquids ?
A. Nusselt equation
B. Sieder-Tate equation
C. Dittus-Boelter equation
D. None of these
Three solid objects of the same material and of equal mass-a sphere, a cylinder (length = diameter) and a cube are at 500°C initially. These are dropped in a quenching bath containing a large volume of cooling oil each attaining the bath temperature eventually. The time required for 90% change in temperature is the smallest for_________________?
A. Cube
B. Sphere
C. Cylinder
D. Equal for all the three
The Fourier number (defined as a.t/L2) is used in the analysis of problem involving heat transfer by_______________?
A. Natural convection
B. Forced convection
C. Transient conduction
D. Steady state conduction
The outlet temperature of cooling water in a heat exchanger is generally not allowed to exceed above 50°C in industrial practice mainly to avoid_________________?
A. Uneconomic LMTD
B. Excessive corrosion
C. Its evaporation loss
D. Decrease in heat exchanger efficiency
Mechanical recompression evaporation is used in the production of____________________?
A. Salt
B. Distilled water
C. Alcohol
D. Fruits jam
The purpose of floating head in a heat exchanger is to_________________?
A. Avoid buckling of tubes
B. Decrease the pressure drop
C. Provide support for tubes
D. Facilitate its lengthening, if needed
The local surface conductance for laminar film condensation on vertical surface is (where, t = film thickness) _________________?
A. ∝ √t
B. ∝ 1/t
C. ∝ t
D. Independent of ‘t’
Baffle spacing ____________________?
A. Should be less than one fifth the diameter of the shell
B. Is not the same as baffle pitch
C. Should be less than the inside diameter of the shell
D. None of these
Latent heat absorbed by 1 lb of water at 212°F, when it is changed to steam at 212°F, may be around ______________ BTU?
A. 180
B. 3.97
C. 970
D. None of these
Chemical Heat Transfer Mcqs
In a shell and tube heat exchanger, the height of 25 percent cut baffles is equal to (where, D = inside diameter of shell) ?
A. 0.50 D
B. 0.25 D
C. 0.75 D
D. None of these
A 2-4 heat exchanger involves__________________?
A. Only parallel-flow of fluids
B. Only counter-flow of fluids
C. Both counter and parallel-flow of the fluids
D. Smaller pressure drop compared to 1-2 exchanger
In a heat exchanger, one transfer unit means___________________?
A. A section of the exchanger in which change in temperature of one stream equals the average driving force in the section
B. The size of the exchanger in which heat transfer rate is 1 kcal/hr
C. Both of the above
D. None of the above
jH factor for heat transfer is not a function of the _______________ number?
A. Reynolds
B. Grashoff
C. Nusselt
D. Both B. & C.
Arithmetic mean area can be used in heat transfer problem to calculate the heat flow by conduction through a cylinder which is ____________________?
A. Thin walled having the value of Ao Ai/< 2
B. Having the value of Ao/Ai > 2
C. Thick walled
D. Both B. and C.
Prandtl and Reynolds analogy are same, when Prandtl number is____________________?
A. > 2
B. 1
C. 0.5
D. 1.5
Overall thermal resistance for conductive heat transfer through a series of flat resistances is equal to the____________________?
A. Average of all resistances
B. Sum of all resistances
C. Maximum resistance in the series
D. Minimum resistance presents in the series
Radiant energy received by a body is proportional to (where, d = the distance between the object emitting radiation and that receiving it.) ?
A. d
B. √d
C. d2
D. d1.5
Boiling point elevation of a solution of NaOH _____________________?
A. Increases rapidly with temperature rise
B. Is almost independent of pressure
C. Is almost independent of temperature
D. Both B. and C
A diathermanous substance _______________ the thermal radiation completely?
A. Reflects
B. Absorbs
C. Transmits
D. None of these
In which mode of heat transfer, the Biot number is important ?
A. Transient heat conduction
B. Forced convection
C. Natural convection
D. Radiation
Among liquids, water has a comparatively high value of thermal conductivity, due to its__________________?
A. High viscosity
B. Low density
C. Partial ionisation
D. Dense structure
The statement that “maximum wavelength of radiation is inversely proportional to the temperature” is ______________ law?
A. Planck’s
B. Stefan-Boltzmann’s
C. Wien’s displacement
D. None of these
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. 1
B. 0
C. > 1
D. < 1
Thermal diffusivity is the most important in heat transfer by__________________?
A. Conduction
B. Condensation
C. Radiation
D. Natural convection
If Prandtl number is greater than the Schmidt number, then the____________________?
A. Thermal boundary layer lies inside the concentration boundary layer
B. Hydrodynamic (i.e., momentum) boundary layer is thicker than the other two
C. Thermal & concentration boundary layers are of equal thickness
D. Concentration boundary layer lies inside the thermal boundary layer
Bulk of the convective heat transfer resistance from a hot tube surface to the fluid flowing in it, is __________________?
A. Uniformly distributed throughout the fluid
B. In the central core of the fluid
C. Mainly confined to a thin film of fluid near the surface
D. None of these