# JNTU II B-Tech I Semester Regular Examinations,Thermal Science- November 2008

JNTU PAPERS

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

THERMAL SCIENCE

( Common to Mechatronics and Production Engineering)

SET-3

1. (a) A non-flow reversible (quasi-static) process can be written down by an equa-

tion (p = v2+8v ) bar. Determine the work done if the volume changes from 1m3 to 3m3.

(b) With an example explain the concept of a cyclic process.

(c) What is meant by boundary of a system?

2. (a) The temperature t on a thermometric scale is defined in terms of a property

k by the relation

t=a loge k +b

Where a and b are constants. The values of k are found to be 1.83 and 6.78 at

the ice point and the steam point, the temperature of which are assigned the

members 0 and 100 respectively. Determine the temperature corresponding

to a reading of k equal to 2.42 on the thermometer.

(b) Write a note on joules experiment?

3. (a) Explain a heat engine cycle performed by a closed system.

(b) Define the thermal efficiency of a heat engine cycle. Can this be 100%?

(c) A heat engine is used to drive a heat pump. The heat transfers from the heat engine and from the heat pump are used to heat the water circulating through the radiators of a building. The efficiency of the heat engine is 27% and the cop of the heat pump is 4. Evaluate the ratio of the heat transfer to the circulating water to the heat transfer to the heat engine.

4. (a) Show that the efficiency of the otto cycle depends only on the compression ratio.

(b) An engine equipped with a cylinder having a bore of 15 cm and a stroke of 45 cm operates on an otto cycle. If hte clearance volume is 2000 cm3, compute the air standard efficiency.

5. (a) Derive the expression for COP of vapour compression refrigeration system in terms of enthalpies.

(b) Explain effects of under cooling and super heating on COP of vapour compression refrigerator system with the help of P-V & T-S diagrams.

6. (a) What are the advantages and disadvantages of a two stroke engine.

(b) With the help of neat sketches, explain the working of two-stroke S.I engine.

7. (a) What are different ill effects of knocking in S.I.engines and suggest the methods

to minimize knocking.

(b) Explain the influence of different operating parameters on ignition delay during

combustion process in C.I.Engine.

8. (a) Describe the working of semi closed type gas turbine unit with suitable figures.

(b) What are the advantages and limitations of closed cycle gas turbine unit.