# GTU previous question papers -BE- Sem-Vth – Conventional Power Engineering-May/June -2012

GTU previous question papers

GUJARAT TECHNOLOGICAL UNIVERSITY

BE- Vth SEMESTER–EXAMINATION – MAY/JUNE – 2012

Subject code: 151906

Subject Name: Conventional Power Engineering

Instructions:

1. Attempt all questions.

2. Make suitable assumptions wherever necessary.

3. Figures to the right indicate full marks.

Q.1 (a) Which are the different methods to improve the performance of Gas

Turbine? Explain each with effects on Gas Turbine performance.

(b) On which cycle thermal power plant works? Explain the cycle with

line diagram. Also plot (T-s) and (h-s) diagram.

Q.2 (a) In an open gas turbine plant, the pressure ratio through which air at

15 0C is compressed is 14. The same air is then heated to a maximum

permissible temperature of 1300 0C first in a heat exchanger which is

75% efficient, and then in the combustion chamber. The air at 1300 0C

is expanded in two stages such that the expansion work is the

maximum. The air is heated to 1300 0C after the high pressure stage.

Determine the cycle thermal efficiency, the work ratio and the net shaft

work per kg of air. The isentropic efficiencies may be assumed to be

85% and 86% for compressor and turbine respectively. Calculate the

flow rate of air for an output of 240 MW. Assume Mechanical and

Generator efficiency 90%.

(b) The velocity of steam entering a simple impulse turbine is 1000 m/s,

and nozzle angle is 210. Mean peripheral velocity of blade is 400 m/s

and blades are symmetrical. If the steam is to enter the blades without

shock, what will be the blade angles?

(a) Neglecting the friction effects on the blades, calculate the tangential

force on the blades and the diagram power for a mass flow of 0.75

kg/s. Estimate also the axial thrust and diagram efficiency.

(b) If the relative velocity at exit is reduced by friction to 80% of that

at inlet, estimate the axial thrust, diagram power and diagram

efficiency

OR

(b) Derive the equation of maximum blade efficiency for single stage

Impulse turbine. And hence derive the equation for maximum power

output per kg of steam.

Q.3 (a) Why governing is necessary in steam turbine? Explain any one

governing method with neat sketch with its effect on performance and

or efficiency of plant (If any).

(b) (I) Define following terms:

Load factor, Plant capacity factor, Plant use factor, Demand factor.

(II)A power station supplies the following loads to the consumers:

Time in

Hr

0-6 6-10 10-12 12-16 16-20 20-22 22-24

MW

30 70 90 60 100 80 60

Draw the load curve and estimate the load factor of the plant.

OR

Q.3 (a) Why compounding is necessary in impulse turbine? Explain pressure –

velocity compounding with pressure velocity diagram.

(b) What is the present status of power generation in India?

Explain the difference in working of three different types of Hydroturbines?

(b) A Francis turbine operates under the following condition: Outer

diameter of runner = 2 m, inner diameter of runner = 1 m,

head = 200 m, specific speed = 130, power developed = 20 MW. The

inclination of water jet with tangential direction = 120. The water

efficiency = 92%. Calculate inlet and outlet blade angles.

OR

Q.4 (a) Explain thermosiphon cooling system with neat sketch and state its

merits and demerits.

(b) Draw the schematic diagram of a diesel electric power plant and

explain the functions of its different components.

Q.5 (a) With neat sketch explain the principal components of Nuclear reactor