PRODUCTION OF HOT AIR WITH QUASI UNIFORM TEMPERATURE USING CONCENTRATED SOLAR-RADIATION

The design of a hot air solar generator for different uses has been si mulated while investigating the flow induced by a hot disc placed at t he entrance of the open ended vertical cylinder. Ambient air (Pr = 0.7 ) enters the bottom of the cylinder with constant velocity and tempera ture, and flows up through the cylinder as a result of natural convect ion. The cylindrical wall is heated by thermal radiation emitted by th e disc. The pressure drop due to acceleration of the flow to the cylin der-inlet causes the appearance of thermosyphon effect around the ther mal plume. At the top part of the cylinder, the flow exploration shows the full development of the turbulence and the uniformity of thermal and hydrodynamic fields. The study of the thermal spectral density ind icates that the turbulent structures seem to be sufficiently small not to be sensitive to viscosity, but large enough to be sensitive to Arc himedes effects. (C) 1998 Elsevier Science Ltd. All rights reserved.