Computational investigation on the factors influencing thermal comfort for impinging jet ventilation: Fid-Bau Portal

Computational investigation on the factors influencing thermal comfort for impinging jet ventilation

Chen, Huijuan / Moshfegh, Bahram / Cehlin, Mathias

Abstract Impinging jet ventilation (IJV) has been proposed to achieve an effective ventilation of an occupied zone in office and industrial buildings. For IJV systems, draught discomfort is the issue of most concern since it supplies cooled air directly to the occupied zone. This study investigated a number of factors influencing draught discomfort and temperature stratification in an office environment equipped with IJV. The factors considered were: shape of air supply device, discharge height, supply airflow rate and supply air temperature. The Response Surface Methodology (RSM) was used to identify the level of the significance of the parameters studied, as well as to develop the predictive models for the local thermal discomfort. Computational fluid dynamics (CFD) was employed to perform a set of required studies, and each simulation condition was determined by the Box–Behnken design (BBD) method. The results indicated that at a low discharge height, the shape of air supply device had a major impact on the flow pattern in the vicinity of the supply device because of the footprint from impinging jet, which consequently affected the draught risk level in the occupied zone. A square-shaped air supply device was found to result in lower overall draught discomfort than rectangular and semi-elliptic shapes. The RSM analysis revealed that the supply airflow rate had a significant impact on the draught discomfort, while the shape of air supply device and discharge height had moderate effects. The temperature stratification in the occupied zone was mostly influenced by the supply air temperature within the range studied.

Highlights • Impacts of different configuration and flow parameters of impinging jet ventilation on local thermal discomfort were studied. • Response Surface Methodology and CFD were used. • Flow pattern near the floor is strongly dependent on the shape of air supply device at a low discharge height. • Draught and temperature gradient is mostly influenced by the supply airflow rate and temperature respectively.