MCQOPTIONS
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MCQOPTIONS
This section includes 968 Mcqs, each offering curated multiple-choice questions to sharpen your GATE (Mechanical Engineering) knowledge and support exam preparation. Choose a topic below to get started.
| 401. |
For a counter current heat exchanger with Tih = 80°C, T°c = 60°C, T°h = 50°C and Tic = 30°C, and the temperature difference between the two streams being the same everywhere along Z, the direction of flow of hot fluid. The temperature profile should satisfy |
| A. | A |
| B. | B |
| C. | C |
| D. | D |
| Answer» C. C | |
| 402. |
In case of surface condensers, a straight line is obtained on plotting 1/U vs __________ on an ordinary graph paper. |
| A. | A |
| B. | B |
| C. | C |
| D. | D |
| Answer» B. B | |
| 403. |
Prandtl number is given by |
| A. | A |
| B. | B |
| C. | C |
| D. | D |
| Answer» D. D | |
| 404. |
What is the geometric mean of two heat transfer areas A1 and A2 ? |
| A. | A |
| B. | B |
| C. | C |
| D. | D |
| Answer» B. B | |
| 405. |
Heat transfer co-efficient (h) for a fluid flowing inside a clean pipe is given by following equation. This is valid for the value of NRe equal to |
| A. | < 2100 |
| B. | 2100-4000 |
| C. | > 4000 |
| D. | > 10000 |
| Answer» E. | |
| 406. |
The number given below is termed as the __________ number. |
| A. | Grashoff |
| B. | Nusselt |
| C. | Prandtl |
| D. | Stanton |
| Answer» D. Stanton | |
| 407. |
Following number is called the __________ number. |
| A. | Peclet |
| B. | Stanton |
| C. | Graetz |
| D. | none of these |
| Answer» D. none of these | |
| 408. |
The following equation is the __________ analogy. |
| A. | Colburn |
| B. | Reynolds |
| C. | Prandtl |
| D. | None of these |
| Answer» B. Reynolds | |
| 409. |
What is the logarithmic mean of r1 and r2 ? |
| A. | A |
| B. | B |
| C. | C |
| D. | D |
| Answer» B. B | |
| 410. |
In which mode of heat transfer, the Biot number is important ? |
| A. | Transient heat conduction |
| B. | Natural convection |
| C. | Forced convection |
| D. | Radiation |
| Answer» B. Natural convection | |
| 411. |
Which of the following has the minimum absorptivity ? |
| A. | Aluminium foil |
| B. | Coal dust |
| C. | Refractory bricks |
| D. | Iron plates |
| Answer» B. Coal dust | |
| 412. |
A sphere of radius 'R1' is enclosed in a sphere of radius 'R2'. The view (or shape) factor for radiative heat transfer of the outer sphere with respect to the inner sphere is |
| A. | 0 |
| B. | R2/(R1+R2) |
| C. | 1 |
| D. | (R1/R2)² |
| Answer» C. 1 | |
| 413. |
Which of the following is concerned with both heat and mass transfer ? |
| A. | Lewis relationship |
| B. | Nusselt number |
| C. | Kutateladze number |
| D. | Froude number |
| Answer» B. Nusselt number | |
| 414. |
A 10 cm diameter 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 |
| A. | greater than that for uninsulated steam pipe. |
| B. | less than that of the uninsulated steam pipe. |
| C. | equal to that of the uninsulated steam pipe. |
| D. | less than the steam pipe with 5 cms insulation. |
| Answer» C. equal to that of the uninsulated steam pipe. | |
| 415. |
Which of the following is not used as a medium for high temperature heating ? |
| A. | Dowtherm |
| B. | mercury |
| C. | liquid metal (e.g. molten sodium) |
| D. | fused salts (e.g., an eutectic mixture of 53% KNO₃, 40% NaNO₂and 7% NaNO₃) |
| Answer» C. liquid metal (e.g. molten sodium) | |
| 416. |
The value of convective coefficient of air in case of free convection is |
| A. | 3-7 W/m² K |
| B. | 3-4 W/m² K |
| C. | 8-9 W/m² K |
| D. | 9-9.5 W/m² K |
| Answer» B. 3-4 W/m² K | |
| 417. |
The nature of fluid flow is governed by following parameters(i) Mean flow velocity(ii) Density of fluid(iii) Dynamic viscosity of the fluidIdentify the correct statements |
| A. | 1 and 3 |
| B. | 1 only |
| C. | 1, 2 and 3 |
| D. | 2 and 3 |
| Answer» D. 2 and 3 | |
| 418. |
How many types of fluid flow are characterized in the realms of fluid mechanics? |
| A. | 1 |
| B. | 2 |
| C. | 3 |
| D. | 4 |
| Answer» C. 3 | |
| 419. |
Following are the characteristics of turbulent flow(i) Eddying(ii) Sinuous(iii) RectilinearIdentify the correct option |
| A. | 2 and 3 |
| B. | 1 and 3 |
| C. | 1, 2 and 3 |
| D. | 1 and 2 |
| Answer» E. | |
| 420. |
In which fluid flow, the motion of fluid particles is irregular? |
| A. | Turbulent |
| B. | Laminar |
| C. | One dimensional |
| D. | Two dimensional |
| Answer» B. Laminar | |
| 421. |
The following equation, corresponds to __________ analogy. |
| A. | Von-Karmann |
| B. | Reynolds |
| C. | Colburn |
| D. | Prandtl |
| Answer» E. | |
| 422. |
For flow over a flat plate, the ratio of thermal boundary layer thickness, 'xt' and hydrodynamic boundary layer thickness 'x' is equal to (where, NPr = Prandtl number) |
| A. | A |
| B. | B |
| C. | C |
| D. | D |
| Answer» C. C | |
| 423. |
Out of the following four assumptions used in the derivation of the equation for LMTD given by below equation, which one is subject to the largest deviation in practice ? |
| A. | Constant overall heat transfer co-efficient. |
| B. | Constant rate of fluid flow. |
| C. | Constant specific heat. |
| D. | No partial phase change in the system. |
| Answer» C. Constant specific heat. | |
| 424. |
The interchange factor for radiation heat transfer from surface 'x' to surface 'y' in case of an infinite parallel planes with emis-sivities εx & εy is given by |
| A. | A |
| B. | B |
| C. | C |
| D. | D |
| Answer» E. | |
| 425. |
Multiple effect evaporators are commonly used in the manufacture of P. Paper Q. Superphosphate R. Sugar S. Fats |
| A. | P and Q |
| B. | P and R |
| C. | P and S |
| D. | R and S |
| Answer» D. R and S | |
| 426. |
What is the unit of thermal conductivity ? |
| A. | Kcal/hr. m² °C |
| B. | Kcal/hr.m.°C |
| C. | Kcal/hr.m |
| D. | Kcal/hr. °C |
| Answer» C. Kcal/hr.m | |
| 427. |
In a shell and tube type heat exchanger, the floating tube bundle heat arrangement is used |
| A. | In low range of temperature differences |
| B. | In high range of temperature differences |
| C. | Because of its low cost |
| D. | To prevent corrosion of the tube bundles |
| Answer» C. Because of its low cost | |
| 428. |
In a forward feed multiple effect evaporator unit |
| A. | Viscosity of liquid is highest in first effect |
| B. | Transfer from effect to effect is done by pumps |
| C. | No pump is required to withdraw the product from the last effect |
| D. | None of these |
| Answer» E. | |
| 429. |
Which is the most suitable for cold viscous feed? |
| A. | Forward feed |
| B. | Backward feed |
| C. | Mixed feed |
| D. | Parallel feed |
| Answer» C. Mixed feed | |
| 430. |
Heat transfer by __________ may not necessarily require the presence of a medium. |
| A. | Conduction |
| B. | Natural convection |
| C. | Forced convection |
| D. | Radiation |
| Answer» E. | |
| 431. |
The characteristic dimensionless groups for heat transfer to a fluid flowing through a pipe in laminar flow are |
| A. | Re.Gz |
| B. | Nu, Pr |
| C. | Nu, Pr, Re |
| D. | Nu, Gz |
| Answer» E. | |
| 432. |
Which of the following is generally considered as opaque surface towards radiations? |
| A. | Gases |
| B. | Solids |
| C. | Liquids |
| D. | Both B and C |
| Answer» E. | |
| 433. |
Electromagnetic radiations propagate in vacuum with a velocity of __________ metre/second. |
| A. | 3 x l05 |
| B. | 3 x l08 |
| C. | 3 x l010 |
| D. | 3 x l012 |
| Answer» C. 3 x l010 | |
| 434. |
The inside heat transfer co-efficient in case of turbulent flow of liquid in the tube side in a 1-2 shell and tube heat exchanger is increased by __________ times, when the number of tube passes is increased to 8. |
| A. | 20.8 |
| B. | 40.8 |
| C. | 40.4 |
| D. | 20.4 |
| Answer» C. 40.4 | |
| 435. |
The variation of thermal conductivity of a metal with temperature is often correlated using an expression of the form K = K₀ + at. where, K is the thermal conductivity and T is the temperature (in °K). The units of 'a' in SI system will be |
| A. | W/m.k |
| B. | W/m |
| C. | W/m.k² |
| D. | None, A is just a number |
| Answer» D. None, A is just a number | |
| 436. |
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. | Its evaporation loss |
| B. | Excessive corrosion |
| C. | Uneconomic LMTD |
| D. | Decrease in heat exchanger efficiency |
| Answer» C. Uneconomic LMTD | |
| 437. |
Dietus-Boelter equation used for the determination of heat transfer co-efficient is valid |
| A. | For fluids in laminar flow |
| B. | For fluids in tubulent flow |
| C. | When Grashhoff number is very important |
| D. | For liquid metals |
| Answer» C. When Grashhoff number is very important | |
| 438. |
For a fluid flowing in an annulus space, the wetted perimeter for heat transfer and pressure drop are |
| A. | Same |
| B. | Different |
| C. | Never different |
| D. | Linearly related |
| Answer» C. Never different | |
| 439. |
With increase in temperature, the total emissivity of conductors |
| A. | Increases |
| B. | Decreases |
| C. | Remains same |
| D. | Decreases linearly |
| Answer» B. Decreases | |
| 440. |
Bulk of the convective heat transfer resistance from a hot tube surface to the fluid flowing in it, is |
| A. | In the central core of the fluid |
| B. | Uniformly distributed throughout the fluid |
| C. | Mainly confined to a thin film of fluid near the surface |
| D. | None of these |
| Answer» D. None of these | |
| 441. |
Prandtl number is the reciprocal of |
| A. | Thermal diffusivity/Momentum diffusivity |
| B. | Thermal diffusivity x Momentum |
| C. | Thermal diffusivity x Mass diffusivity |
| D. | Mass diffusivity x Momentum diffusivity |
| Answer» B. Thermal diffusivity x Momentum | |
| 442. |
Nusselt number (for forced convection heat transfer) is a function of the __________ number. |
| A. | Prandtl |
| B. | Reynolds |
| C. | Both A & B |
| D. | Neither A nor B |
| Answer» D. Neither A nor B | |
| 443. |
jH factor for heat transfer is not a function of the __________ number. |
| A. | Reynolds |
| B. | Nusselt |
| C. | Grashoff |
| D. | Both B & C |
| Answer» E. | |
| 444. |
One kilogram of water at 0°C is changed to superheated steam of one atm pressure and 300° C. The major heat consumption in the process will be to |
| A. | Heat the water from 0°C to 100°C |
| B. | Evaporate the water |
| C. | To superheat the steam |
| D. | Data insufficient, can |
| Answer» C. To superheat the steam | |
| 445. |
In a single evaporator system, the steam economy __________ by creating vacuum in the evaporator. |
| A. | Increases |
| B. | Decreases |
| C. | Remains constant |
| D. | May increase or decrease, depends on the vacuum |
| Answer» B. Decreases | |
| 446. |
For gases, the thermal conductivity increases with temperature rise. For liquids, with increase in concentration, its thermal conductivity generally |
| A. | Decreases |
| B. | Increases |
| C. | Remains unchanged |
| D. | Increases exponentially |
| Answer» B. Increases | |
| 447. |
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 | |
| 448. |
Thickness of thermal boundary layer is more compared to that of hydrodynamic boundary layer, when the value of Prandtl number is |
| A. | 1 |
| B. | < 1 |
| C. | > 1 |
| D. | > 5 |
| Answer» C. > 1 | |
| 449. |
The steam ejector is used to |
| A. | Remove condensate from the steam pipelines |
| B. | Create vacuum |
| C. | Superheat the steam |
| D. | None of these |
| Answer» C. Superheat the steam | |
| 450. |
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 |
| A. | Finned tube heat exchanger with air inside and steam outside |
| B. | Finned tube heat exchanger with air outside and steam inside |
| C. | Shell and tube heat exchanger with air inside tubes and steam on shell side |
| D. | Shell and tube heat exchanger with air on shell side and steam inside tubes |
| Answer» C. Shell and tube heat exchanger with air inside tubes and steam on shell side | |