## Machine Design MCQ Set 1

1. Which of the following reboiler is considering as an additional tray?

a) Jacketed kettle

b) Internal reboiler

c) Kettle-reboiler

d) None of the mentioned

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2. The internal reboilers are preferred for maintaining economy of an industry.

a) True

b) False

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3. The vertical-syphon reboilers are not preferred because of

a) Fouling

b) Overheat

c) Large tubes

d) None of the mentioned

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4. Jacketed kettle are preferred for kettle type reboiler.

a) True

b) False

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5. The reboiler which is most preferred is

a) External

b) Internal

c) Middle

d) All the mentioned

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6. Find the condenser location.

a) X

b) Y

c) Z

d) No condenser

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7. Condenser or reboiler is consider as a trays or stage in a fractionator.

a) True

b) False

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8. The fuel fired furnace is preferred for high boiling point.

a) True

b) False

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9. Will this arrangement is possible and effective.

a) True

b) False

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10. Most reboilers are

a) Heat regulators

b) Heat exchangers

c) Heat analyser

d) Heat rectifiers

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## Machine Design MCQ Set 2

1. Most economical cost is

a) Minimum cost

b) Optimum cost

c) Balanced cost

d) Fixed cost

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2. Consider an operating line touches the equilibrium line, and then the fixed cost becomes

a) Minimum

b) Infinite

c) No fixed cost

d) None of the mentioned

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3. If the operating cost is low, then the fixed cost is more.

a) True

b) False

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4. If the reflux ratio increases _________ increases.

a) Fixed cost

b) Operating cost

c) Optimum

d) All of the mentioned

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5. If the reflux increases ________ increases in the fractionator.

a) Diameter

b) Length

c) Volume

d) None of the mentioned

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6. Total cost is

a) Operating + optimum cost

b) Fixed + optimum cost

c) Fixed + operating cost

d) None of the mentioned

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7. At optimum reflux ratio,

a) Operating and optimum cost are equal

b) Operating and fixed cost are equal

c) Fixed and optimum cost are equal

d) Total and optimum cost are equal

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8. Total cost will be minimum at

a) Minimum reflux ratio

b) Maximum reflux ratio

c) Optimum reflux ratio

d) None of the mentioned

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9. A designer gave us a report on distillation column and said he was perfect.

a) True

b) False

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10. Estimate the fixed cost if the operational cost is 7 lakhs and the total cost is 15 lakhs.

a) 21 lakhs

b) 8 lakhs

c) 7 lakhs

d) None of the mentioned

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11. Estimate the operational cost if the fixed cost is 15 lakhs.

(Hint: reflux ratio= optimum)

a) 15 lakhs

b) 30 lakhs

c) 0

d) None of the mentioned

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## Machine Design MCQ Set 3

1. In respect to free convection over a vertical flat plate, the Nusselt number for laminar and turbulent flows varies respectively with Grashoff number G _{r} as

a) G _{r} and G _{r}^{1/4}

b) G _{r}^{1/2} and G _{r}^{1/3}

c) G _{r}^{1/4} and G _{r}^{1/3}

d) G _{r}^{1/3} and G _{r}^{1/4}

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_{r}

^{1/4}and G

_{r}

^{1/3}.

2. Experimental results indicate that the local heat transfer coefficient h _{g} for flow over a flat plate with an extremely rough surface is approximated by the relation

h _{x} = a x^{ -0.12}

Where a is a constant coefficient and x is distance from the leading edge of the plate. What is the relation between this local heat transfer coefficient and the average heat transfer coefficient for a plate of length x?

a) 1.136 h _{x}

b) 2.136 h _{x}

c) 3.136 h _{x}

d) 4.136 h _{x}

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^{-0.12 }= 1.136 h

_{x}.

3. For the free convection circumstances, the following dimensionless numbers apply

(i) Grashof number

(ii) Prandtl number

(iii) Nusselt number

Identify the correct answer

a) 2 and 3

b) 2 only

c) 1 and 2

d) 1, 2 and 3

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4. Two horizontal steam mains with diameters 5 cm and 15 cm are to be laid in a boiler house that any mutual heat effect is precluded. The mains are at the same surface temperature of 500 degree Celsius whilst the ambient air is at 50 degree Celsius. Workout the ratios of the heat transfer coefficients

a) 0.136

b) 1.316

c) 2.136

d) 3.136

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_{1}/h

_{ 2}= (d

_{2}/d

_{1})

^{ 0.25 }= 1.136.

5. Consider the above problem, workout the heat losses from one meter length of the mains

a) 0.458

b) 0.448

c) 0.438

d) 0.428

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_{1}/Q

_{ 2}= h

_{1 }d

_{1 }l/h

_{ 2 }d

_{2 }l = 0.438.

6. A spherical heater of 20 cm diameter and at 60 degree Celsius is immersed in a tank of water at 20 degree Celsius. Determine the value of convective heat transfer coefficient

a) 458.32 W/m^{2 }K

b) 558.32 W/m^{2 }K

c) 658.32 W/m^{2 }K

d) 758.32 W/m^{2 }K

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^{2 }K.

7. A steam pipe 50 mm diameter and 2.5 m long has been placed horizontally and exposed to still air at 25 degree Celsius. If the pipe wall temperature is 295 degree Celsius, determine the rate of heat loss. At the mean temperature difference of 160 degree Celsius, the thermo-physical properties of air are

k =3.64 * 10 ^{-2} W/m K

v =30.09 * 10 ^{-6} m^{2}/s

P _{r} =0.682

Β =1/160 + 273 = 2.31 * 10 ^{-3} per K

a) 1156.5 W

b) 1146.5 W

c) 1136.5 W

d) 1126.5 W

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8. Consider the above problem, find out the Grashof number

a) 0.8447 * 10 ^{5}

b) 0.8447 * 10 ^{6}

c) 0.8447 * 10 ^{7}

d) 0.8447 * 10 ^{8}

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^{3}P

^{ 2}(β g d t)/µ

^{ 2}.

9. Estimate the heat transfer from a 40 W incandescent bulb at 125 degree Celsius to 25 degree Celsius in quiescent air. Approximate the bulb as a 50 mm diameter sphere. The approximate correlation for the convection coefficient is

Nu = 0.60 (Gr Pr) ^{0.25}

Where the different parameters are evaluated at the mean film temperature, and characteristics length is the diameter of the sphere

a) 4.71 W

b) 5.71 W

c) 6.71 W

d) 7.71 W

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10. Consider the above problem, find what percent of power is lost by free convection?

a) 19.478%

b) 19.378%

c) 19.278%

d) 19.178%

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## Machine Design MCQ Set 4

1. Find the moisture to be evaporated per kg of dried product if initial and final moisture content per kg of dry solid is 85% and 15%.

a) 0.5

b) 0.6

c) 0.7

d) 0.8

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2. Convert 80% of moisture in wet basis to dry basis ( kg water/kg dry solid)

a) 4

b) 8

c) 12

d) 16

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3. If the equilibrium vapour pressure is lower than pure liquid pressure then the moisture content is ___________

a) Bound moisture

b) Unbound moisture

c) Equilibrium moisture

d) None of the mentioned

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4. The substance moisture exerts equilibrium vapour pressure equals to vapour pressure of liquid is ________

a) Bound moisture

b) Unbound moisture

c) Equilibrium moisture

d) None of the mentioned

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5. The moisture which can be evaporated is bound moisture.

a) True

b) False

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6. The method of drying by conduction through materials are done by _________

a) Direct driers

b) Indirect driers

c) Tray driers

d) None of the mentioned

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7. The substance like food stuff, pharma products are dried by _______ drying.

a) Direct

b) Indirect

c) Freeze

d) None of the mentioned

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8. The representation AB is known as

a) Bound moisture

b) Unbound moisture

c) Equilibrium moisture

d) None of the mentioned

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9.The name of the curve between relative humidity and moisture content is equilibrium moisture curve.

a) True

b) False

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10. Convert 5 kg of moisture /kg of dry solid to wet basis.

a) 3/6

b) 4/6

c) 5/6

d) 1

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## Machine Design MCQ Set 5

1. Find the time taken to dry 50% to 40% of moisture (dry basis) if critical moisture content is 30%. If the weight of the wet solid is 5 kg and the product of area and constant rate is 0.5 kg/min.

a) 20 sec

b) 40 sec

c) 60 sec

d) 80 sec

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2. Find the period if the initial and the final moisture content are 60% and 40%. Also the critical moisture content is 30%.

a) Constant rate period

b) Falling rate period

c) Unsaturated period

d) None of the mentioned

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3. Find the period if the initial and the final moisture content are 50% and 20%. Also the critical moisture content is 30%.

a) Constant rate period

b) Falling rate period

c) saturated period

d) None of the mentioned

.

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4. At the constant drying period of a batch process, the rate of drying varies accordingly.

a) True

b) False

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5. Find the change in moisture content from the given data

Given data:

Time for drying= 6 sec

Area * Constant rate = 8 kg per sec

Weight of wet solid = 100 kg

a) 0.21

b) 0.12

c) 0.48

d) 0.84

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6. Find the initial moisture content for the batch process if the final moisture content is 25% (dry basis) and the constant moisture content is 40%. (Includes constant and falling rate period)

a) 35

b) 30

c) 60

d) None of the mentioned

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7. Find the final moisture content for the batch process if the initial moisture content is 75% (dry basis) and the constant moisture content is 40%. (Includes constant and falling rate period)

a) 45

b) 50

c) 60

d) None of the mentioned

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8. Falling rate period of a batch process starts at

a) Saturated drying surface

b) Unsaturated drying surface

c) Both unsaturated and saturated region

d) None of the mentioned

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9. If the time taken for the moisture removal is obtained from the formula

Time = Ss(Xc – Xe)/ Nc * A ln ((X1-Xe)/(X2-Xe)) then the falling curve will be curves symmetrically

Where, Ss= Wet solid weight

Xc,Xe- constant & equilibrium moisture content

X1,X2 – initial and final moisture content

a) True

b) False

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10. There will be a change in rate of drying of a batch process after the constant drying process.

a) True

b) False

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11. Find the Constant rate representation

a) X

b) Y

c) Z

d) A

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12. Find the representation of critical moisture content value

a) A

b) B

c) Z

d) Y

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13. Find the equilibrium content value

a) A

b) B

c) C

d) Y

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14. Falling rate period of the batch drying curve = _______ + ___________

a) Internal movement, unsaturated surface drying

b) Internal movement, saturated surface drying

c) External movement, unsaturated surface drying

d) External movement, saturated surface drying

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15. Find the region if the final and the initial moisture content are 40% and 30% (Dry basis) and the critical moisture content is 45%.

a) Constant rate

b) Falling rate

c) Internal movement

d) None of the mentioned