AEC 2023 CEC Preliminary Round Day 3

Which option is accurate regarding one dimensional heat transfer?

• Steady – f(x, y, t),

  Unsteady – f(x)

• Steady – f(y, z),

  Unsteady – f(y)

• Steady – f(x, t),

  Unsteady – f(x)

• Steady – f(x), Unsteady – f(x, t)

Helium is produced on commercial scale from:

• Air

• Coke oven gas

• Natural gas

• None of these

Choose the correct statements about crude oil.

I. Produced from petroleum.

II. Can be found floating on ponds or streams.

III. An important source of energy.

IV. Has different compositions at different locations.

• I and II

• II and III

• I, III and IV

• II, III and IV

A natural gas pipeline has an internal diameter of 30 centimetres and a length of 500 metres. The pipeline transports natural gas at a flow rate of 10,000 cubic metres per hour. The natural gas has a density of 0.7 kg/m^3 and a velocity of 5 metres per second. What is the mass flow rate of natural gas through the pipeline? 

• 3.02 kg/second

• 1.94 kg/second

• 1.08 kg/second

• 1.56 kg/second

Transition from laminar to turbulent zone in free convection heat transfer is governed by the critical value of

• Grashoff number & Prandtl number.

• Reynolds number.

• Grashoff number & Reynolds number.

• Grashoff number.

Total reflux in a distillation operation requires minimum

• reboiler load.

• condenser load.

• number of plates.

• all of the above.

On moving the feed line (q-line) from saturated liquid feed (vertical position) to saturated vapour feed (horizontal feed), if the slope of both the operating lines are to be increased, then it will result in

• increased reflux ratio.

• increased reboiler load.

• greater degree of separation with a fixed number of trays.

• none of these.

A high-octane number means that the fuel will have:

• High knock resistance but low compressibility

• High knock resistance and high compressibility

• Low knock resistance but high compressibility

• Low knock resistance and low compressibility

 Which of the following is the correct expression for the first law of thermodynamics?

• Q = U + W

• ∆E = Q + W

• ∆U = Q - W

• W = -P∆V

What is the purpose of proppants in fracking?

• To create fractures in the rock

• To increase the permeability of the rock

• To hold open the fractures created by the injected fluids 

• None of the above