Paper Conference

Proceedings of BauSim Conference 2014: 5th Conference of IBPSA-Germany and Austria


CFD-Studie zur intermittierenden BelÜftung von Räumen – Potenzialanalyse und vereinfachte Modellierung

E. Lichtner, M. Kriegel

Abstract: An intermittently used mixing ventilation system was examined on a generic room model by means of CFD software. It was ascertained that auxiliary energy could be saved and the ventilation efficiency could be increased at the same level of comfort, both in full load and part load operation. Auxiliary energy is saved due to the decrease in volume flow. At full load, this occurs by allowing a greater difference in temperature between supply air and exhaust air. Lowering the volume flow according to room occupancy is sensible for part load operation. In general, a significant decrease in volume flow in steady-state operation leads to a notable deviation from the standard configuration. This results in reduced ventilation efficiency and thus a decrease in air quality, which causes discomfort. The increased comfort with intermittent ventilation is reached by air pulsation at high momentum. The supply air velocity has a great effect on the discharge momentum of the jet of air. If the supply air volume flow of a room is reduced, the supply air velocity sinks, as does the discharge momentum. A larger discharge momentum can be reached by increasing the supply air velocity. To achieve the same average volume flow, the supply air can be sent in periodically.
Pages: 536 - 540