MCQOPTIONS
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MCQOPTIONS
This section includes 657 Mcqs, each offering curated multiple-choice questions to sharpen your Testing Subject knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
If Prandtl number is greater than the Schmidt number, then the____________________? |
| A. | Thermal boundary layer lies inside the concentration boundary layer |
| B. | Concentration boundary layer lies inside the thermal boundary layer |
| C. | Thermal & concentration boundary layers are of equal thickness |
| D. | Hydrodynamic (i.e., momentum) boundary layer is thicker than the other two |
| Answer» B. Concentration boundary layer lies inside the thermal boundary layer | |
| 2. |
If heat transfer rate varies with the time, it is termed as__________________? |
| A. | Forced convection |
| B. | Steady state conduction |
| C. | Monochromatic radiation |
| D. | None of these |
| Answer» E. | |
| 3. |
If h1 = inner film co-efficient and /h2 = outer film co-efficient, then the overall heat transfer co-efficient is________________? |
| A. | Always less than h1 |
| B. | Always between h1 and h2 |
| C. | Always higher than h2 |
| D. | Dependent on metal resistance |
| Answer» C. Always higher than h2 | |
| 4. |
If average heat transfer co-efficient is ha and the local coefficient at the end of the plate is hl then in case of heat transfer to a fluid flowing over a flat plate, heated over its entire length________________? |
| A. | ha = hl |
| B. | ha = 2hl |
| C. | ha = 0.5 hl |
| D. | ha = 0.75 hl |
| Answer» C. ha = 0.5 hl | |
| 5. |
If all the conditions and dimensions are same, then the ratio of velocity through the tubes of a double pass heat exchanger to that through the single pass heat exchanger is_________________? |
| A. | 1 |
| B. | 2 |
| C. | 1/2 |
| D. | 4 |
| Answer» C. 1/2 | |
| 6. |
If air (a non-condensing gas) is present in a condensing vapor stream, it will ______________ the condensation rate of vapor? |
| A. | Increase |
| B. | Decrease |
| C. | Not affect |
| D. | Increase the condensing film co-efficient as well as |
| Answer» C. Not affect | |
| 7. |
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. | Increase by 1.8 times |
| B. | Decrease by 22 |
| C. | Increase by 216 |
| D. | Remain unchanged |
| Answer» D. Remain unchanged | |
| 8. |
Hot water (0.01 m3 /min) enters the tube side of a counter current shell and tube heat exchanger at 80°C and leaves at 50°C. Cold oil (0.05 m3/min) of density 800 kg/m3 and specific heat of 2 kJ/kg.K enters at 20°C. The log mean temperature difference in °C is approximately ? |
| A. | 32 |
| B. | 37 |
| C. | 45 |
| D. | 50 |
| Answer» B. 37 | |
| 9. |
Heat waves_____________________? |
| A. | Cannot pass through vacuum |
| B. | Travel in straight line |
| C. | Can be reflected by a mirror |
| D. | Both B. and C. |
| Answer» E. | |
| 10. |
Heat transfer rate per unit area is called_________________? |
| A. | Thermal conductivity |
| B. | Heat flux |
| C. | Heat transfer co-efficient |
| D. | Thermal diffusivity |
| Answer» C. Heat transfer co-efficient | |
| 11. |
Heat transfer rate described by Fourier’s law will decrease, if the _____________ increases? |
| A. | Thermal conductivity |
| B. | Thickness |
| C. | Temperature difference |
| D. | Heat transfer area |
| Answer» C. Temperature difference | |
| 12. |
Heat transfer occurs by natural convection because change in temperature causes difference in__________________? |
| A. | Viscosity |
| B. | Density |
| C. | Thermal conductivity |
| D. | Heat capacity |
| Answer» C. Thermal conductivity | |
| 13. |
Heat transfer in the laminar sub-layer in case of a liquid flowing through a pipe, is mostly by__________________? |
| A. | Eddies current |
| B. | Conduction |
| C. | Convection |
| D. | None of these |
| Answer» C. Convection | |
| 14. |
Heat transfer efficiency leading of energy conservation in a heat exchanger can be achieved by____________________? |
| A. | Keeping the heat transfer surface clean |
| B. | Enhancing the fluid pumping rate |
| C. | Increasing the tube length |
| D. | None of these |
| Answer» B. Enhancing the fluid pumping rate | |
| 15. |
Heat transfer co-efficient (h1) for liquids increases with__________________? |
| A. | Increasing temperature |
| B. | Decreasing temperature |
| C. | Decreasing Reynolds number |
| D. | None of these |
| Answer» B. Decreasing temperature | |
| 16. |
Heat transfer co-efficient (h) for a fluid flowing inside a clean pipe is given by h = 0.023 (K/D) (DVρ/μ)0.8 (CP.μ/k)0.4. This is valid for the value of NRe equal to_______________? |
| A. | 4000 |
| B. | > 10000 |
| Answer» C. | |
| 17. |
Heat transfer co-efficient equation for forced convection, Nu = 0.023 Re 0.8. Pr n, is not valid, if the value of __________________? |
| A. | n = 0.4 is used for heating |
| B. | n = 0.3 is used for cooling |
| C. | Reynolds number for the flow involved is > 10000 |
| D. | Reynolds number for the flow involved is < 2100 |
| Answer» E. | |
| 18. |
Heat transfer by radiation between two bodies at T1 & T2 and in an ambient temperature of Ta°C depends on_____________? |
| A. | T1 – T2 |
| B. | T1 – Ta |
| C. | T2 – Ta |
| D. | None of these |
| Answer» E. | |
| 19. |
Heat transfer by natural convection is enhanced in system with__________________? |
| A. | High viscosity |
| B. | High co-efficient of thermal expansion |
| C. | Low temperature gradients |
| D. | Low density change with temperature |
| Answer» C. Low temperature gradients | |
| 20. |
Heat transfer by ____________ may not necessarily require the presence of a medium? |
| A. | Conduction |
| B. | Natural convection |
| C. | Forced convection |
| D. | Radiation |
| Answer» E. | |
| 21. |
Heat transfer by conduction results due to the transfer of free electrons, kinetic energy & vibrational energy from one molecule to another. Conduction heat transfer cannot take place____________________? |
| A. | Between two bodies in physical contact with each other |
| B. | Between two bodies not in physical contact with each other |
| C. | From one part of a body to the another part of the same body |
| D. | Both B & C |
| Answer» C. From one part of a body to the another part of the same body | |
| 22. |
Heat transfer by conduction in the turbulent core of a fluid flowing through a heated pipe is negligible, if the value of Prandtl number is_______________? |
| A. | 0.2 |
| B. | 0.4 |
| C. | 0.6 |
| D. | 0.8 |
| Answer» D. 0.8 | |
| 23. |
Heat sensitive materials can be concentrated in an evaporator employing_______________? |
| A. | Vacuum |
| B. | High pressure |
| C. | High residence time |
| D. | None of these |
| Answer» B. High pressure | |
| 24. |
Heat produced when a steady state current, I passes through an electrical conductor having resistance, ‘R’ is___________________? |
| A. | IR |
| B. | I2R |
| C. | IR2 |
| D. | I2R2 |
| Answer» C. IR2 | |
| 25. |
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 |
| Answer» D. None of these | |
| 26. |
Heat flux is the time rate of heat transfer per unit_______________? |
| A. | Length |
| B. | Area |
| C. | Volume |
| D. | None of these |
| Answer» C. Volume | |
| 27. |
Heat flux increases with temperature drop beyond the Leiden frost point in the plot of heat flux vs. temperature drop for a boiling liquid, because___________________? |
| A. | Convection becomes important |
| B. | Conduction becomes important |
| C. | Radiation becomes important |
| D. | Sub-cooled boiling occurs |
| Answer» D. Sub-cooled boiling occurs | |
| 28. |
Heat flux, as defined in heat flow is analogous to _______________ in electricity flow? |
| A. | Current |
| B. | Voltage |
| C. | Resistance |
| D. | None of these |
| Answer» B. Voltage | |
| 29. |
Heat exchangers operating, when the asymptotic range is reached, ? |
| A. | Provide very large heat transfer co-efficient |
| B. | Results in making part of the heating surface inactive |
| C. | Results in abruptly increased velocity |
| D. | None of these |
| Answer» C. Results in abruptly increased velocity | |
| 30. |
Heat exchanger tubes are never made of_________________? |
| A. | Plain carbon steel |
| B. | Stainless steel |
| C. | Lead |
| D. | Copper |
| Answer» D. Copper | |
| 31. |
_____________ heat exchanger is used for chilling oil to be dewaxed? |
| A. | U-tube |
| B. | Double pipe |
| C. | Fixed tube |
| D. | Floating head |
| Answer» C. Fixed tube | |
| 32. |
_____________ heat exchanger is the most suitable, when the temperature of shell side fluid is much higher than that of tube side? |
| A. | Single pass, fixed tube sheet |
| B. | U-tube |
| C. | Three pass, fixed tube sheet |
| D. | None of these |
| Answer» C. Three pass, fixed tube sheet | |
| 33. |
Harmonic mean temperature difference is given by_________________? |
| A. | √(ΔT1 . ΔT2) |
| B. | 2 (ΔT1 . ΔT2)/(ΔT1 + ΔT2) |
| C. | 2 (ΔT1 . ΔT2)/(ΔT1 – ΔT2) |
| D. | (ΔT1 – ΔT2)/(ΔT1 . ΔT2) |
| Answer» C. 2 (ΔT1 . ΔT2)/(ΔT1 – ΔT2) | |
| 34. |
Grashoff number is given by________________? |
| A. | gD3.β.Δtρ2/μ2 |
| B. | gD2βΔtρ/μ2 |
| C. | gD2βΔtP2μ |
| D. | gD3βΔtP2/μ |
| Answer» B. gD2βΔtρ/μ2 | |
| 35. |
Grashoff number, which is defined as g . β (Ts – T∞) ρ2. L3/μ2, is proportional to the ratio of buoyancy force to ____________ force? |
| A. | Viscous |
| B. | Elastic |
| C. | Inertial |
| D. | None of these |
| Answer» B. Elastic | |
| 36. |
Graetz number is given by__________________? |
| A. | mCp/kL |
| B. | kL/mCp |
| C. | mCp/kμ |
| D. | kμ/mCp |
| Answer» B. kL/mCp | |
| 37. |
Fruit juice (a heat sensitive material) can be concentrated in a ____________ evaporator? |
| A. | Long tube |
| B. | Falling film |
| C. | High pressure |
| D. | None of these |
| Answer» C. High pressure | |
| 38. |
Fresh orange juice contains 12% (by weight) solids and the rest water 90% of the fresh juice is sent to an evaporator to remove water and subsequently mixed with the remaining 10% of fresh juice. The resultant product contains 40% solids. The kg of water removed from 1 kg fresh juice is__________________? |
| A. | 0.4 |
| B. | 0.5 |
| C. | 0.6 |
| D. | 0.7 |
| Answer» E. | |
| 39. |
Fqra cold viscous feed, backward feed gives _____________ than forward feed? |
| A. | A higher capacity |
| B. | A lower capacity |
| C. | Lower economy |
| D. | None of these |
| Answer» B. A lower capacity | |
| 40. |
Fourier’s law of heat conduction applies to _____________ surfaces? |
| A. | Isothermal |
| B. | Non-isothermal |
| C. | Both A. and B. |
| D. | Neither A. and B. |
| Answer» D. Neither A. and B. | |
| 41. |
Fourier’s law applies to the heat transfer by__________________? |
| A. | Convection |
| B. | Radiation |
| C. | Conduction |
| D. | All A., B. & C. |
| Answer» D. All A., B. & C. | |
| 42. |
Fouling factor_____________________? |
| A. | Is a dimensionless quantity |
| B. | Does not provide a safety factor for design |
| C. | Accounts for additional resistances to heat flow |
| D. | None of these |
| Answer» D. None of these | |
| 43. |
‘Fouling factor’ used in the design of a multipass shell and tube heat exchanger is a_____________________? |
| A. | Non-dimensional factor |
| B. | Factor of safety |
| C. | Conversion factor for individual film heat transfer co-efficient to overall heat transfer coefficient |
| D. | None of these |
| Answer» C. Conversion factor for individual film heat transfer co-efficient to overall heat transfer coefficient | |
| 44. |
Fouling factor for a heat exchanger is given by (where, U1 = heat transfer co-efficient of dirty surface U2 = heat transfer co-efficient of clean surface) ? |
| A. | U1 – U2 |
| B. | 1/U1 – 1/U2 |
| C. | 1/U2 – 1/U1 |
| D. | U2 – U1 |
| Answer» C. 1/U2 – 1/U1 | |
| 45. |
Forced circulation evaporators are useful for the concentration of viscous, salting and scale forming liquors. Which of the following is a forced circulation evaporator ? |
| A. | Long vertical evaporator |
| B. | Horizontal tube evaporator |
| C. | Agitated film evaporator |
| D. | Calandria vertical tube evaporator |
| Answer» D. Calandria vertical tube evaporator | |
| 46. |
Forced circulation evaporators are normally used for concentrating liquids having ___________________? |
| A. | Scaling characteristics |
| B. | High viscosity |
| C. | Both A. & B. |
| D. | Neither A. nor B. |
| Answer» D. Neither A. nor B. | |
| 47. |
For what value of Prandtl number, St = f/2 ? |
| A. | 1.5 |
| B. | 1 |
| C. | > 1 |
| D. | < 1 |
| Answer» C. > 1 | |
| 48. |
For turbulent flow in a tube, the heat transfer co-efficient is obtained from the Dittus- Boelter correlation. If the tube diameter is halved and the flow rate is doubled, then the heat transfer co-efficient will change by a factor of________________? |
| A. | 1 |
| B. | 1.74 |
| C. | 6.1 |
| D. | 37 |
| Answer» D. 37 | |
| 49. |
For the same heat load and mass flow rate in the tube side of a shell and tube heat exchanger, one may use multipass on the tube side, because it__________________? |
| A. | Decreases the pressure drop |
| B. | Decreases the outlet temperature of cooling medium |
| C. | Increases the overall heat transfer coefficient |
| D. | None of these |
| Answer» D. None of these | |
| 50. |
For the same heat transfer area and the terminal conditions, the ratio of the capacities of a single effect evaporator to a triple effect evaporator is_________________? |
| A. | 3 |
| B. | 0.33 |
| C. | 1 |
| D. | 1.33 |
| Answer» D. 1.33 | |