Assignment #II

Date of issue:$12/11/2023$

Q$1.$Calculate the top loss coefficient for an absorber with a single Date of Submission:$30/11/2023$ specifications:

Plate$-$to$-$cover spacing

Plate emittance

Ambient air and sky temperature

Wind heat transfer coefficient

Mean plate temperature

Collector tilt

Glass emittance

$30mm$

$0\mathrm{.}85$

$11C$

$11\frac{W}{m^2}C$

$110C$

$40$

$0\mathrm{.}85$

Q$2.$ For the collector of with a top loss coefficient of $7\frac{W}{m^2}C$ and overall loss coefficient of $9\frac{W}{m^2}C,$ design the collector bank length and width assuming the length of the collector as $3$ times its width. Take the additional specifications as:

Back$-$insulation thickness $=60mm$

Insulation conductivity $=0\mathrm{.}06\frac{W}{m}C$

Collector area $=50m^2$

Collector thickness $=80mm$

Edge insulation thickness $=30mm.$

Q$3.$ Wind turbine units are rated at $2MW$ in a rated wind speed of $13\frac{m}{s}.$ The performance coefficient $(Cp)$ is $0\mathrm{.}32,$ turbine efficiency and generator efficiency is $94\%.$ What is the necessary swept area and rotor diameter. Take density of air as $1\mathrm{.}29k\frac{g}{m^3}.$

Q$4.$ i$)$ Draw a neat sketch of a horizontal axis wind turbine generator with its main components. Explain briefly the function of each component?

ii$)$ Compare Horizontal wind axis machine and Vertical wind axis machine.

Q$5.$ i$)$ Photovoltaic $($PV$)$ systems convert light energy directly into electricity. Briefly describe how do they work?

ii$)$ Mention the types of PV cells and give their applications