Chemical Engineering Gate 2011 Questions with Answer

Ques 40 GATE 2011

A transporter receives the same number of orders each day. Currently, he has some pending orders (backlog) to be shipped. If he uses 7 trucks, then at the end of the 4th day he can clear all the orders. Alternatively, if he uses only 3 trucks, then all the orders are cleared at the end of the 10th day. What is the minimum number of trucks required so that there will be no pending order at the end of the 5th day?

Ques 41 GATE 2011

Consider two black bodies with surfaces S₁ (area=1m²) and S₂ (area=4 m²). They exchange heat only by radiation. 40% of the energy emitted by S_I is received by S₂. The fraction of energy emitted by S₂ that is received by S₁ is

Ques 42 GATE 2011

In film type condensation over a vertical tube, local heat transfer coefficient is

Ques 43 GATE 2011

Oil at 120°C is used to heat water at 30°C in a 1-1 co-current shell and tube heat exchanger. The available heat exchange area is S₁. The exit temperatures of the oil and the water streams are 90°C and 60°C respectively. The co-current heat exchanger is replaced by a 1-1 counter-current heat exchanger having heat exchange area S₂. If the exit temperatures and the overall heat transfer coefficients are same, the ratio of S₁ to S₂ is

Ques 44 GATE 2011

Heat is generated uniformly within a solid slab. The slab separates fluid 1 from fluid 2. The heat transfer coefficients between the solid slab and the fluids are h₁ and h₂(h₂>h₁) respectively. The steady state temperature profile (T vs. x) for one-dimensional heat transfer is CORRECTLY shown by

Ques 45 GATE 2011

A PID controller output p(t), in time domain, is given by p(t)=30+5e(t)+1.25∫₀^te(t)dt+15(de(t)/dt) where e(t) is the error at time t. The transfer function of the process to be controlled is G_p(s)=10/(200s+1). The measurement of the controlled variable is instantaneous and accurate.
The transfer function of the controller is

Ques 46 GATE 2011

A PID controller output p(t), in time domain, is given by p(t)=30+5e(t)+1.25∫₀^te(t)dt+15(de(t)/dt) where e(t) is the error at time t. The transfer function of the process to be controlled is G_p(s)=10/(200s+1). The measurement of the controlled variable is instantaneous and accurate.
The characteristic equation of the closed loop is

Ques 47 GATE 2011

Match the process parameters in Group I with the measuring instruments in Group II
GROUP I
P. Flame temperature
Q. Composition of LPG
R. Liquid air temperature
GROUP II
I. Thermocouple
II. Radiation pyrometer
III. Gas chromatograph

Ques 48 GATE 2011

The range of standard current signal in process instruments is 4 to 20 mA. Which ONE of the following is the reason for choosing the minimum signal as 4 mA instead of 0 mA?

Ques 49 GATE 2011

The following diagram shows a CSTR with two control loops. A liquid phase, endothermic reaction is taking place in the CSTR, and the system is initially at steady state. Assume that the changes in physical properties of the system are negligible.

Ques 50 GATE 2011

Ammonia is synthesised at 200 bar and 773 K by the reaction N₂+3H₂↔2NH₃. The yield of ammonia is 0.45 mol/mol of fresh feed. Flow sheet for the process (along with available compositions) is shown below.

Ques 51 GATE 2011

The following combustion reactions occur when methane is burnt.
CH₄+2O₂→CO₂+2H₂O
2CH₄+3O₂→2CO+4H₂O
20% excess air is supplied to the combustor. The conversion of methane is 80% and the molar ratio of CO to CO₂ in the flue gas is 1:3. Assume air to have 80 mol % N₂ and rest O₂. The O₂ consumed as a PERCENTAGE of O₂ entering the combustor is

Ques 52 GATE 2011

Simultaneous heat and mass transfer is occurring in a fluid flowing over a flat plate. The flow is laminar. The concentration boundary layer will COINCIDE with the thermal boundary layer, when