Jawaharlal Nehru Technological University Hyderabad
Jawaharlal Nehru Technological University Hyderabad B.Tech III NON-CONVENTIONAL POWER GENERATION Previous Question Paper (March - 2021 - R16)
Answer any five questions
All questions carry equal marks
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Main
What features of solar energy make it attractive for use in irrigation water pump? With a schematic diagram, explain the working of a solar thermal water pump.
Answer
Solar energy is highly attractive for irrigation because it is abundant in rural agricultural regions, requires minimal maintenance, eliminates fuel costs, and provides power exactly when irrigation demand is highest (during sunny days). Solar thermal pumps convert solar radiation into thermal energy to drive a heat engine or a vapor-based cycle to lift water.
The system consists of a solar collector (flat plate or concentrating), a working fluid loop, a heat exchanger, and a pump. The solar collector absorbs radiation, heating the working fluid. This fluid vaporizes and expands in a prime mover (like a Rankine cycle turbine or an oscillating piston), which provides the mechanical work to operate the water pump. The vapor is then condensed and recirculated back to the collector.
What is solar time, and why is it different from standard clock time of the country? Derive an expression for solar day length.
Answer
Solar time is based on the sun's apparent position in the sky, where noon is defined as the moment the sun reaches its highest point (meridian). It differs from standard clock time because clock time is based on a fixed longitudinal meridian (Standard Meridian) and ignores the Earth's elliptical orbit and axial tilt, which cause the sun to appear to speed up or slow down throughout the year (Equation of Time).
The solar day length is derived from the sunset hour angle, ωs. At sunset, the solar altitude angle α is 0, satisfying the equation:
where φ is the latitude and δ is the solar declination. The day length (in hours) is calculated by converting the hour angle from degrees to time:
With a schematic diagram, explain the working of a solar pond electric power plant.
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Calculate the angle of incidence on a horizontal plane surface at Kolkata at 14.00 hrs IST on March 21st in a leap year. The north, longitude and latitude of Kolkata are 88° 20′ E and 22° 32′ N respectively. The standard longitude of IST is 81° 44′ E.
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With a neat sketch, discuss the operating characteristics of photo voltaic module.
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Explain the design considerations/strategies for MPPT operations.
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Explain the following systems used for converting solar radiation into electrical energy:
(i) Central receiver system (ii) Distributed collector system.
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Draw the equivalent circuit of a solar cell, and discuss its V – I characteristics.
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Wind blows with a velocity of 15 m/s at 15°C and 1 standard atm pressure. The turbine diameter is 120 m with operating speed of 40 rpm at maximum efficiency. Propeller type wind turbine is considered. Calculate the following: (a) total power density in the wind stream, (b) the maximum obtainable power density, (c) a reasonably obtainable power density, (d) total power, (e) torque at maximum efficiency and (f) maximum axial thrust. Assume R = 0.287 kJ/kg K and efficiency = 35 %.
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Explain the basic principle of wind energy conversion.
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Discuss the merits and demerits associated with wind energy systems.
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List out various types of Geothermal resources.
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The following data are given for a family biogas digester suitable for the output of four cows:
Retention time = 22 days; Temperature = 30°C; Dry matter consumed = 1.8 kg/day; Biogas yield = 0.25 m3 per kg; Burner efficiency = 60%; Methane proportion = 0.82; Heat of combustion of Methane may be assumed as 28 MJ/m3 at STP.
Calculate the volume of the biogas digester and the power available from the digester.
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Explain the total flow concept of liquid-dominated geothermal system.
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List the factors affecting biogas generation. Explain any four in brief.
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