Renewable Energy Sources - May 2015

Mechanical Engineering (Semester 8)

TOTAL MARKS: 100
TOTAL TIME: 3 HOURS (1) Question 1 is compulsory.
(2) Attempt any four from the remaining questions.
(3) Assume data wherever required.
(4) Figures to the right indicate full marks.

1 (a) What is the importance of 'Non-Conventional Energy Source's in the context of Present Energy Scenario? (8 marks)

1 (b) Explain energy status of India & Maharashtra and role of NCES. (8 marks)

1 (c) Define the solar constant. What is its value? (4 marks)

2 (a) Define and explain the following:
i) latitude angle
ii) Hour angle iii) Declination angle iv) Day length. (8 marks)

2 (b) Estimate the monthly average daily global radiation on a horizontal surface at Ratnagiri (16°59' N, 72°05' E) during the 16^th march if the average sunshine hours per day is 9.5. Assume the value of a=0.31 and b=0.43. (7 marks)

2 (c) Find the days of the year on which the sun is directly overhead at 1200 h (LAT) at Pune (18°32' N). (5 marks)

3 (a) What is Betz coefficient? Show that the maximum power coefficient is 59% for a horizontal axis wind mill. (10 marks)

3 (b) The following data are given for a family biogas digester suitable for the output of 10 cows; the retention time is 30 days, temperature 30°C, dry meter consumed 2kg/day/cow, and biogas yield is 0.24 m³ per kg. The efficiency of burner is 60%, methane proportion is 0.8. Heat of combustion of methane is 28 MJ/m³. Calculate the volume of digester and the power available from the digester. Assume density of dry material in the fluid is 50 kg/m³. (10 marks)

4 (a) A tidal power plant of the simple single basin type has a basin area of 30×10⁶ m². The tide has a range of 12m. The turbine however stops operating when the head on it fall below 3 m. Calculate the energy generated in one filling (or emptying) process, in kWh if the turbine generator efficiency =73%. (8 marks)

4 (b) Explain with neat sketches, how energy from Geothermal source can be obtained in different ways. (5 marks)

4 (c) Propeller type wind turbine of 120 m diameter is running with 40 rmp at a velocity of 15 m/s with maximum efficiency. The atmospheric pressure is 1.01325 bar and the temperature is 15°C Calculate:
i) The total power density in the wind stream
ii) The maximum obtainable power density.
iii) The total power. (7 marks)

5 (a) Plot the variation of τ_r, τ_α and τ with the angle of incidence for the following cover system:

5 (b) Describe with a neat sketch the working of wind energy system showing the main components. Discuss advantages of wind energy conversion systems. (10 marks)

6 (a) Draw a neat diagram and explain working of a KVIC design of biogas digester? (10 marks)

6 (b) How can wave energy be utilized? (10 marks)

Write short notes on any four:

7 (a) Utilization of tidal energy. (5 marks)

7 (b) Site selection considerations for wind mill (5 marks)

7 (c) Fuel cells (5 marks)

7 (d) Micro-hydro power generation (5 marks)

7 (e) Operational and environmental problems of geothermal energy. (5 marks)