Master's Thesis Tobias BurgholzCopyright: EBC
In the context of room ventilation, both the maintenance of good air quality and the provision of a comfortable environment are crucial. Thermal comfort strongly depends on the distribution of local air velocities and temperatures within the occupied zone. The concept of air distribution impacts both air flow field and thermal comfort significantly.
As part of this thesis, a new test bench software is designed and implemented using LabVIEW, and 17 experiments with different combinations of spefific cooling loads, specific volume flows and supply air temperatures are conducted. The main goal is the investigation of the limitations to the applicability of displacement ventilation regaring the provision of a thermally comfortable environment in buildings. Based on the percentage of persons affected by draughts, vertical differences in air temperatures and cold or warm floor surfaces, all configurations are assigned to (if possible) one of three thermal environment categories introduced in DIN EN ISO 7730, with category A imposing the highest and category C imposing the lowest requirements.
The results show that, depending on the respective volumeflow, significant draught ratings are likely to occur along with little vertical temperature gradients, and vice versa. As primary air is introduced immediately above floor level, local draught ratings peak at ankle height. Vertical air temperature
differences between feet and head level of standing persons range from 2 to 8,3 K. On the contrary, neither cooling load nor volume flow appear to have an impact on the surface temperature of the floor. Due to both excessive draught ratings and vertical temperature gradients, none of the 17 setups that were investigated meet the requirements of DIN EN ISO 7730.