Experimental investigation of the velocity field and air flow pattern generated by cooling ceiling beams.

In the modem office environment there are numerous heat generating equipment. In addition there are loads from solar radiation and heat produced by people. Therefore, the loads will often exceed.the load the ventilation system can cope with. To meet this demand on extra cooling capacity the commercial market provides cooling ceiling panels and cooling beams. A literature review shows that until now the majority of the research has been focused on the cooling performance and only a minor part on the thermal comfort and air quality. A cooling beam is a source of natural convection, creating a transport of cold air into the occupied zone. Furthermore, natural convection flows are vulnerable to disturbances. Experiments have been conducted in a mock up of an office room. A large variety of heating loads have been used. Qualitative information has been obtained by the use of visualisation, registered by a digital video camera. The time history of velocity and temperature has been registered. The change in position (oscillations) with time of the air-flow generated by the chilled beam has been documented by the use of small and fast thermo-couples and thermistor anemometers. The results show that the air-flow from the chilled beam exhibits strong oscillations both sideways and along the chilled beam. Furthermore, air-flow generated by heat sources in the room may reverse the flow generated by the chilled beam.