JNTU
JNTU B.Tech III NON-CONVENTIONAL POWER GENERATION Previous Question Paper (March - 2021 - R16)
Answer any five questions. All questions carry equal marks. Illustrate your answers with NEAT sketches wherever necessary.
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 areas where grid connectivity is often unreliable. It provides a sustainable, maintenance-free, and cost-effective long-term solution that operates precisely when water demand is highest (during sunny days). Solar pumps eliminate fuel costs and environmental pollution associated with diesel pumps.
A solar thermal water pump works by converting solar radiation into thermal energy to drive a heat engine. The system consists of a solar collector (flat plate or parabolic), a heat exchanger, a working fluid (with a low boiling point), and a pump. The solar collector heats the working fluid, which vaporizes and expands to drive a piston or turbine connected to the water pump. The vapor is then condensed back into liquid in a heat exchanger cooled by the pumped water, completing the cycle.
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 position in the sky, where noon occurs when the sun reaches its highest point (meridian). It differs from standard clock time because standard time is based on a fixed longitudinal meridian for an entire time zone, whereas solar time varies continuously with longitude. Furthermore, the Earth's elliptical orbit and axial tilt cause the actual solar day to fluctuate throughout the year (the Equation of Time).
To derive the day length, consider the sunset/sunrise hour angle
where
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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