JNTU question papers B -Tech Ist Sem – Fluid mechanics for chemical engineering – Nov 2008

JNTU II B.Tech I Semester Supplimentary Examinations, November 2008

FLUID MECHANICS FOR CHEMICAL ENGINEERING

(Chemical Engineering) SET-2

 

 

1. A tubular centrifuge bowl with an inside diameter of 150 mm, rotating at 8000 r/min. is to separate chlorobenzene, with a density of 1109 kg/m3, from an aqueous wash liquid having a density of 1020 kg/m3. The free-liquid surface inside the bowl is 40 mm from the axis of rotation. If the centrifuge bowl is to contain equal volumes of the two liquids, what should be the radial distance from the rotational axis to the top of the overflow dam for heavy liquid?

 

2. Write short notes on:

(a) Viscosity and Momentum flux

(b) Time dependent flow of fluids

(c) A pipe of 20 cm and length 10m is used to transport oil of Sp.gr is 0.9 and viscosity 1.5 poise. The oil is pumped at a rate of 20 lit/s. Find the average velocity and Reynolds Number.

 

3. Carbon tetra chloride is to flow through a smooth horizontal circular tube of inner diameter 3cm with a volumetric flow rate of 2 lt /s. at 250C. Estimate the pressure loss per cm length of the pipe. Density and viscosity are 1.54g/cc and 0.87 cp respectively.Friction factor f = 0.0014+Re – 0.32.

 

4. (a) Derive the equation of continuity of compressible fluids. State the assumptions clearly.

(b) Methane gas is being pumped through a 305m length of 52.5mm diameter steel pipe at a rate of 41.0kg/m2-s.The inlet and outlet pressure is 345kPa abs and 298kPa. Assume isothermal flow at 288.8K.Calculate the maximum velocity that can be obtained at these conditions.

 

5. (a) Explain the forces acting on a particle moving through a fluid.

(b) Estimate the terminal velocity for a particles of diameter 0.161mm and density 2800Kg/m3 falling in water at 300C by gravity.(CD= 7.9).

 

6. Derive the expression relating the terminal velocity of the particles and the minimum fluidizing velocity for low Reynolds number.

 

7. (a) Describe the working and merits of ball valves.

(b) Draw the typical curves of fluid power and total power versus flow rate for a centrifugal pump and explain them.

 

8. (a) Discuss the advantages and limitations of a centrifugal compressor than reciprocating compressor.

(b) Describe the working of thermal meters used for flow measurement.

 

 

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