Abstract :
The useful heat gain of a parabolic collector system is directly dependent on the heat loss from the absorber at its operating temperature.
Selective coatings with evacuated/non evacuated glass tubes are employed to control radiative and convective heat losses. A concentric
glass shell under vacuum is investigated for its thermal performance as this method circumvents the need for direct sealing
between the glass envelope and the metal receiver to maintain vacuum and its related technical challenges. The performance is compared
against a non evacuated receiver and its influence under different wind velocities; emissivities are calculated by a one dimensional theoretical
model and solved by an iterative method.
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