An Experimental Investigation of Free Convection Cooling of Electronic Equipment : A Printed-Wiring-Board Placed Horizontally within Cabinet

An experiment was carried out to study free convection cooling of electronic components on a PWB placed horizontally within the cabinet. The cabinets (200mm×150mm in cross-section 80mm high), which were made from acrylic resins plates (4mm thick), had the ventilating many small holes in the front panel and the bottom panel. The ratio of the ventilating hole area in the front panel to the front panel inside area was altered by changing the diameter of each hole. The effects of the ventilation on the hottest temperature in the PWB are cleared quantitatively by using this ventilating area ratio. The flow pattern in the cabinets was visualised by using the tobacco smoke and the laser beam. It seemed that there was a close connection between the flow pattern and the location of the hot spot on the PWB, and that the ventilating holes in the bottom was not useful for cooling the PWB.