JNTU PAPERS

JNTU,B.Tech,I- Semester, Thermal Science, November 2008

( Mechatronics and Production Engineering)

SET-4

1. (a) State whether the following properties of a system are intensive or extensive.

Give justification:

pressure, temperature, mass, density, volume, specific volume, energy and velocity.

(b) A mass of 2.5 kg of air is compressed in a quasi static process from 0.1 MPa to 0.7 MPa for which PV = constant. The initial specific volume is 0.80 m^{3}/kg. Find the work done by the piston to compress the air

2. In a steady flow apparatus, 135 kJ of work is done by each kg of fluid. The specific

volume of the fluid, pressure, and velocity at the inlet are 0.37 m^{3}/kg, 600 KPa,

and 16 m/s. The inlet is 32 m above the floor, and the discharge pipe is at floor

level, The discharge conditions are 0.62 m3/kg, 100 KPa and 270 m/s. The total

heat loss between the inlet and discharge is 9 KJ/kg of fluid. In flowing through,

does the internal energy increase or decrease, and by how much?

3. (a) State and prove the principle of increase of entropy.

(b) During summer to cool water for drinking purpose 1kg of ice at -20C is mixed

with 5kg of water at 270C is an isolated container which is subjected to atmospheric pressure of 1bar. Calculate the temperature of this mixture and the change in entropy for the spontaneous process. Assume specific heat of ice as 2.093 KJ/Kgh and latent heat of ice as 335 KJ/Kg.

4. (a) Explain the dual combustion cycle? Derive an expression for the efficiency of

dual cycle?

(b) If the mean effective pressure of diesel cycle is 7.5 bar and the compression

ratio is 12.5. Find the percentage cut off of the cycle if the initial pressure is 1 bar.

5. (a) Describe the working of a Bell-Coleman refrigeration system with a neat sketch. What are its merits over other refrigeration systems?

(b) What are the various desirable properties of a refrigerant? State any two commercially used refrigerants?

6. (a) How the C.I. engine fuels are rated? Explain the required qualities of C.I. engine fuels.

(b) How to control the speed variations in C.I. engine? Explain.

7. (a) Explain the phenomena of detonation in S.I. Engine? How it is different from

C.I. Engine

(b) What are different uses of cooling in I. C. Engines?

8. (a) Draw the schematic diagram of regenerative gas turbine unit. Explain it’s

working along with p-V and T-s diagrams.

(b) Derive the thermal efficiency of gas turbine unit with inter cooling.