GATE BT topic:transport-processes PYQs & Answers — Page 2

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topic:transport-processes

Questions 11–20 of 24. Imported answers require independent review unless marked reviewed.

Topic practice 24 questionsPage 2 of 3

Fermentation medium is cooled from 121 °C to 30 °C in a double pipe heat exchanger. If cold water is flowing in the counter-current direction and is heated from 10 °C to 70 °C, then the Log-Mean Temperature Difference (LMTD) is ______ °C (rounded off to the nearest integer).

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Aspergillus niger is grown in a 10,000 L stirred batch bioreactor under aerated conditions to produce citric acid. At steady state oxygen transfer conditions, the specific oxygen uptake rate of the organism and the volumetric mass transfer coefficient are

and 60 min

, respectively.

If the oxygen solubility is

kg m

under the operating conditions, based only on oxygen dynamics, the maximum possible cell concentration is ______ kg m

(Answer in integer).

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Ethanol is produced in a 10,000 L stirred bioreactor using an impeller of diameter 1 m. The density and viscosity of fermentation broth are 1000 kg m

and 1 cp, respectively. The data relating the Power number and Impeller Reynolds number is given below:

| Reynolds number | 1-5 | 5-500 | > 10

| | Power number | 70 | 10 | 5 |

Using the above data, the power required for the stirrer to operate at 300 rpm is ______ kW (Answer in integer).

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The values of the consistency index ‘K’ and the flow behavior index ‘n’ of a dilatant fluid are 0.415 (in CGS units) and 1.23, respectively. The value of the apparent viscosity (in

) of this fluid at a shear rate of

(rounded off to the nearest integer) is ____________.

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An evaporator is insulated using glass wool material of 0.15 m thickness. The inner most surface and the outer surface of the insulation are at 700 °C and 80 °C, respectively. The mean thermal conductivity of the glass wool under these conditions is 0.29 W m

. The rate of heat loss (in W) through 1.2 m

of the evaporator wall surface (rounded off to the nearest integer) is ____________.

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For a double-pipe heat exchanger, the inside and outside heat transfer coefficients are 100 and 200 W m

, respectively. The thickness and thermal conductivity of the thin-walled inner pipe are 1 cm and 10 W m

, respectively. The value of the overall heat transfer coefficient is ________ W m

Your answerChoose one option.

0.016

42.5

62.5

310

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A fermentation broth of density 1000 kg m

and viscosity 10

kg m

is mixed in a 100 L fermenter using a 0.1 m diameter impeller, rotating at a speed of 2 s

. The impeller Reynolds number is ________________.

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Liquid-phase mass transfer coefficient (

) is measured in a stirred tank vessel using steady-state method by sparging air. Oxygen uptake by the microorganism is measured. The bulk concentration of O

mol L

. Solubility of O

in water at 25 °C is

mol L

If the oxygen consumption rate is

mol L

, and interfacial area is 100 m

, the value of

is __________ cm s

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A sedimentation tank of height 100 cm is used in a conventional activated sludge process to separate a suspension of spherical shaped granular sludge biomass of 0.5 mm diameter. The viscosity of the liquid is 1 cP. The difference in density between the suspended biomass and the liquid is 0.1 g cm⁻³. If the biomass reach their terminal velocity instantaneously, the biomass settling time in min (rounded off to two decimal places) is _____.

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Milk flowing through a stainless steel inner tube (40 mm inner diameter) of double tube-type heater is to be heated from

by saturated steam condensing at

on the outer surface of the inner tube. Total heat transferred (

) is

and the overall heat transfer coefficient is

. The total length of the heating tube in

(rounded off to one decimal place) is ________.

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GATE BT topic:transport-processes PYQs

Question 54

Question 55

Question 56

Question 62

Question 63

Question 13

Question 34

Question 60

Question 47

Question 52