GATE CH format:nat PYQs & Answers — Page 12

Questions 111–120 of 252. Imported answers require independent review unless marked reviewed.

Topic practice 252 questionsPage 12 of 26

A cylindrical fin of diameter 24 mm is attached horizontally to a vertical plane wall. The heat transfer rate from the fin to the surrounding air is 60% of the heat transfer rate if the entire fin were at the wall temperature. If the fin effectiveness is 10, its length is __________ mm (rounded off to the nearest integer).

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A single-effect evaporator with a heat transfer area of 70 m

concentrates a salt solution using steam. The salt solution feed rate and temperature are 1000 kg h

and 40 °C, respectively. The saturated steam feed rate and temperature are 750 kg h

and 150 °C, respectively. The boiling temperature of the solution in the evaporator is 80 °C. The average specific heat of the solution is 0.8 kcal kg

. The latent heat of vaporization is 500 kcal kg

. If the steam-economy is 0.8, the overall heat transfer coefficient is ______ kcal h

(rounded off to the nearest integer).

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An equimolar binary mixture is to be separated in a simple tray-distillation column. The feed rate is 50 kmol min

. The mole fractions of the more volatile component in the top and bottom products are 0.90 and 0.01, respectively. The feed as well as the reflux stream are saturated liquids. On application of the McCabe-Thiele method, the operating line for the stripping section is obtained as

where

and

are the mole fractions of the more volatile component in the vapor and liquid phases, respectively. The reflux ratio is ______ (rounded off to two decimal places).

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The dry-bulb temperature of air in a room is 30 °C. The Antoine equation for water is given as

where

is the temperature in K and

is the saturation vapor pressure in bar. The latent heat of vaporization of water is 2000 kJ kg

, the humid heat is 1.0 kJ kg

, and the molecular weights of air and water are 28 kg kmol

and 18 kg kmol

, respectively. If the absolute humidity of air is

kg moisture per kg dry air, then for a wet-bulb depression of 9 °C,

________________ (rounded off to one decimal place).

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In the block diagram shown in the figure, the transfer function

with

and

. The maximum value of

below which the system remains stable is __________ (rounded off to two decimal places).

Diagram for Chemical Engineering question 58

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Consider the tank level control system shown in the figure, where the cross-section area of the tank is

. Assume perfect flow controllers (FC). The level controller (LC) is proportional-integral (PI). For an integral time,

, the level controller gain,

, is tuned for critical damping. The value of

is ______ (rounded off to the nearest integer).

Diagram for Chemical Engineering question 59

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Consider a single-input-single-output (SISO) system with the transfer function

where the time constants are in minutes. The system is forced by a unit step input at time

. The time at which the output response reaches the maximum is __________ minutes (rounded off to two decimal places).

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Information for a proposed greenfield project is provided in the table. The discounted cash flow for the fourth year is Rs ________ crores (rounded off to one decimal place).

Item	Value
Fixed capital investment (excluding land)	Rs 250 crores
Salvage value	Rs 0
Yearly revenue from product sales	Rs 120 crores
Yearly manufacturing cost (excluding depreciation)	Rs 30 crores
Interest rate	10% compounded annually
Annual taxation rate	30%
Depreciation method	Double declining balance over seven years
Plant start-up	2 years after project initiation

;

: years post start-up;

: Depreciation amount;

: Book value

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Consider the process in the figure. The liquid phase elementary reactions

occur in the continuous stirred tank reactor (CSTR), where

is the mole fraction of the

component (

) in the CSTR. It is given that

. All process feed, process exit and recycle streams are pure. At steady state, the net generation rate of the undesired product,

, in the CSTR is zero.

is varied at constant reactor temperature, the reactor volume is adjusted to maintain a constant single-pass conversion of

. For a fixed product rate and 90% conversion of

in the reactor, the value of

that minimizes the sum of the molar flow rates of the A and S recycle streams is ______ (round off to one decimal place).

Diagram for Chemical Engineering question 62

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An elementary irreversible liquid-phase reaction,

, is carried out under isothermal conditions in a

ideal plug flow reactor (PFR) as shown in the figure. The volumetric flow rate of fresh A,

and its concentration

. For a recycle ratio

, the conversion of A at location 2 with respect to the fresh feed (location 1) is 50%. For

, the corresponding conversion of A is _______% (rounded off to one decimal place).

Diagram for Chemical Engineering question 63

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GATE CH format:nat PYQs

Question 54

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Question 56

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Question 58

Question 59

Question 60

Question 61

Question 62

Question 63