Applied Thermodynamics - II, Question Paper of Mechanical Engineering 4th Semester, Download Question Paper Applied Thermodynamics 3

Roll No.

Total No. of Questions: 09

B. Tech. (ME) (Sem.-4th)

APPLIED THERMODYNAMICS - I

Subject Code: BTME-404

Paper ID: [A1214]

Time: 3 Hrs.

INSTRUCTIONS TO CANDIDATE:

1. Section-A is compulsory.

2. Attempt any four questions from Section-B.

3. Attempt any two questions from Section-C.

SECTION–A

Q1. Write briefly:

a) How will you classify the air compressor?

b) Define the term “Compressor capacity”.

c) What is the difference between a rotary and a reciprocating compressor?

d) Write the steady flow energy equation for a compressor.

e) What is slip as applied to compressors.

f) Define the term surging.

g) Why is the pre guide vanes provided in a centrifugal compressor?

h) State the principle of jet propulsion.

i) List he methods of thermal refinement for a gas turbine cycle

j) Define the term “work ratio’ for a gas turbine.

SECTION-B

Q2. In a two stage air compressor in which the intercooling is perfect. prove that the work

done in compression is minimum when the pressure in the intercooler is geometric mean

between initial and final pressures.

Q3. Explain the phenomenon of surging and chocking in a centrifugal compressor.

Q4. With the help of a neat sketch discus the working of a vane blower compressor.

Q5. Discus in details different methods of improving the efficiency and specific output of a simple gas turbine.

Q6. The following data refers to a turbo-jet flying at an altitude of 950m:

sped of turbojet=80km/hr

Propulsive efficiency=5%

Overall efficiency of the turbine plant=17%

Density of air at 950m altitude=0.17kg/m3

Drag on the plane=610N

Assuming the calorific value of fuel as 4600kj/kg calculate (i) Absolute velocity of the jet (i) Volume of air compressed per min (i) Diameter of jet (iv) Power output of Unit

SECTION-C

Q7. A centrifugal compressor compressed 4.8m3/s of air from 1 bar and 20oc to 1.5 bar. The index of compression n is 1.5. The flow velocity at inlet and outlet of the machine is the

same and equal to 65m/s. The inlet and outlet impeller diameters are 0.32m and 0.62m respectively. The blower rotates at 800 r.p.m. Calculate: (i) The blade angles at inlet and outlet of the impeller (i) The breadth of blade at inlet and outlet. It may be assumed that no diffuser is employed and al the pressure increase takes place in impeller and blades have negligible thickness. Q8. In an air-standard regenerative gas turbine cycle the pressure ratio is 5. Air enters the compressor at 1 bar, 30 K and leaves at 490 K. The maximum temperature in the cycle

is 100K. Calculate the cycle efficiency given that the efficiency of the regenerator and the adiabatic efficiency of the turbine both are 80%. Take γ=1.4 for air.

Also draw the T-s diagram for the cycle

Q9. A multi-stage axial flow compressor delivers 20kg/s of air. The inlet stagnation

condition is 1 bar and 17oC. The power consumed by the compressor is 4350KW.

Calculate (i) Delivery pressure (i) Number of stages (i) Overall isentropic efficiency of the compressor. Assume temperature rise in the firsts stage is 15oC, the polytrophic efficiency of compression is 8% and the stage stagnation pressure ratio is constant.