Chemical Engineering Gate Yearwise 


Chemical Engineering Gate 2019 Questions with Answer

Ques 40 GATE 2019

A solid sphere of radius 1 cm and initial temperature of 25 °C is exposed to a gas stream at 100 °C. For the solid sphere, the density is 104 kg/m3 and the specific heat capacity is 500 J/(kg K). The density of the gas is 0.6 kg/m3 and its specific heat capacity is 103 J/(kg K). The solid sphere is approximated as a lumped system (Biot number << 1) and all specific heats are constant. If the heat transfer coefficient between the solid and gas is 50 W/(m2 K), the time (in seconds) needed for the sphere to reach 95 °C is ______ (rounded off to the nearest integer).


(902) is the correct answer.

Ques 41 GATE 2019

Stream A with specific heat capacity CPA = 2000 J/(kg K) is cooled from 90 °C to 45 °C in a concentric double pipe counter current heat exchanger having a heat transfer area of 8 m2. The cold stream B of specific heat capacity CPB = 1000 J/(kg K) enters the exchanger at a flow rate 1 kg/s and 40 °C. The overall heat transfer coefficient U = 250 W/(m2 K). Assume that the mean driving force is based on the arithmetic mean temperature difference, that is, [ΔT]AMTD = (TA,in + TA,out)/2 - (TB,in + TB,out)/2 where Ti,in and Ti,out refer to the temperature of the ith stream (i = A, B) at the inlet and exit, respectively. The mass flow rate of stream A (in kg/s), is ______ (rounded off to two decimal places).


(0.31) is the correct answer.

Ques 42 GATE 2019

A 20 cm diameter cylindrical solid pellet of a nuclear fuel with density 6000 kg/m3 and conductivity of 300 W/(m K) generates heat by nuclear fission at a spatially uniform rate of 104 W/kg. The heat from the fuel pellet is transferred to the surrounding coolant by convection such that the pellet wall temperature remains constant at 300 °C. Neglecting the axial and azimuthal dependence, the maximum temperature (in °C) in the pellet at steady state is ______ (rounded off to the nearest integer).


(800) is the correct answer.

Ques 43 GATE 2019

A thermocouple senses temperature based on the

A

Nernst Effect

B

Maxwell Effect

C

Seebeck Effect

D

Peltier Effect


(c) is the correct answer.

Ques 44 GATE 2019

The liquid flow rate through an equal percentage control valve, when fully open, is 150 gal/min and the corresponding pressure drop is 50 psi. If the specific gravity of the liquid is 0.8, then the valve coefficient, Cv, in gal/(min psi0.5) is ______ (rounded off to two decimal places).


(18.97) is the correct answer.

Ques 45 GATE 2019

Consider two non-interacting tanks-in-series as shown in figure. Water enters TANK 1 at q cm3/s and drains down to TANK 2 by gravity at a rate k√h (cm3/s). Similarly, water drains from TANK 2 by gravity at a rate of k√h2 (cm3/s) where h1 and h2 represent levels of TANK 1 and TANK 2, respectively (see figure). Drain valve constant k = 4 cm2.5/s and cross-sectional areas of the two tanks are A1 = A2 = 28 cm2.

At steady state operation, the water inlet flow rate is qss = 16 cm3/s. The transfer function relating the deviation variables h''2(s) (cm) to q''(s) (cm3/s) is,

A

$\frac{2}{(56s+1)^{2}}$

B

$\frac{2}{(62s+1)^{2}}$

C

$\frac{2}{(36s+1)^{2}}$

D

$\frac{2}{(49s+1)^{2}}$


(a) is the correct answer.

Ques 46 GATE 2019

Choose the option that correctly matches the step response curves on the left with the appropriate transfer functions on the right. The step input change occurs at time t=0.

A

P-III, Q-IV; R-II, S-I

B

P-III, QI; R-IV, S-II

C

P-IV, Q-III; R-II, S-I

D

P-III, Q-II; R-IV, S-I


(b) is the correct answer.

Ques 47 GATE 2019

For the closed loop system shown in figure, the phase margin (in degrees) is ______ (rounded off to one decimal place).


(45.4) is the correct answer.

Ques 48 GATE 2019

The correct expression for the Colburn j-factor for mass transfer that relates Sherwood number (Sh), Reynolds number (Re) and Schmidt number (Sc) is __________.

A

$\frac{Sh}{(Re)(Sc)^{1/3}}$

B

$\frac{Sh}{(Re)^{1/2}(Sc)}$

C

$\frac{Sh}{(Re)^{1/2}(Sc)^{1/3}}$

D

$\frac{Sh}{(Re)(Sc)}$


(a) is the correct answer.

Ques 49 GATE 2019

In the drying of non-dissolving solids at constant drying conditions, the internal movement of moisture in the solid has a dominant effect on the drying rate during

A

the initial adjustment period only

B

the constant rate period only

C

the falling rate period only

D

both the initial adjustment and constant rate periods


(c) is the correct answer.

Ques 50 GATE 2019

Three distillation schemes for separating an equimolar, constant relative volatility ABC mixture into nearly pure components are shown. The usual simplifying assumptions such as constant molal overflow, negligible heat loss, ideal trays are valid. All the schemes are designed for minimum total reboiler duty. Given that the relative volatilities are in the ratio
αA:αB:αC=8:2:1,
the correct option that arranges the optimally-designed schemes in ascending order of total reboiler duty is __________.

A

I, II, III

B

III, I, II

C

II, I, III

D

III, II, I


(b) is the correct answer.

Ques 51 GATE 2019

Consider a sealed rigid bottle containing CO2 and H2O at 10 bar and ambient temperature. Assume that the gas phase in the bottle is pure CO2 and follows the ideal gas law. The liquid phase in the bottle contains CO2 dissolved in H2O and is an ideal solution. The Henry''s constant at the system pressure and temperature is HCO2 = 1000 bar. The equilibrium mole fraction of CO2 dissolved in H2O is ______ (rounded off to three decimal places).


(0.010) is the correct answer.

Ques 52 GATE 2019

100 kg of a feed containing 50 wt.% of a solute C is contacted with 80 kg of a solvent containing 0.5 wt.% of C in a mixer-settler unit. From this operation, the resultant extract and raffinate phases contain 40 wt.% and 20 wt.% of C, respectively. If E and R denote the mass of the extract and raffinate phases, respectively, the ratio E/R is

A

$1/4$

B

$1/2$

C

$2/3$

D

1


(c) is the correct answer.

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