JNTUH B.Tech IV NON-CONVENTIONAL SOURCES OF ENERGY Previous Question Paper (September - 2022 - R18)

Solar radiation reaching the Earth's surface is significantly less than the solar constant due to several attenuation processes as it passes through the atmosphere:

• Absorption: Atmospheric gases, primarily ozone, water vapor, and carbon dioxide, absorb specific wavelengths of solar radiation. Ozone absorbs ultraviolet radiation, while water vapor and carbon dioxide absorb infrared radiation.
• Scattering: Gas molecules, dust particles, and aerosols scatter solar radiation in all directions. Rayleigh scattering occurs due to small gas molecules, while Mie scattering occurs due to larger particles like dust and smoke, reducing the intensity of the direct beam.
• Reflection: Clouds and the Earth's surface reflect a portion of the incoming solar radiation back into space, a phenomenon measured by the Earth's albedo.
• Air Mass: The path length of radiation through the atmosphere depends on the sun's zenith angle. At lower sun positions, the radiation travels through a thicker layer of the atmosphere, leading to increased absorption and scattering.

To calculate the angle of incidence (θ) for a surface tilted at an angle β, we use the formula:

Given: Latitude (φ) = 28.633° N, Tilt (β) = 36°, Hour angle (ω) = -45° (at 9:00 AM, 15° per hour from solar noon).

For December 1st (n = 335), the declination angle (δ) is calculated as:

Substituting the values:

The angle made by the beam radiation with the normal to the collector is 45.75°.