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Thermal and draught perception in fluctuating stratified thermal environments with intermittent impinging jet ventilation

Zhou, Bin; Li, Zhe; Yang, Bin; Li, Xiaojing; Wang, Faming; Wei, Shen; (2023) Thermal and draught perception in fluctuating stratified thermal environments with intermittent impinging jet ventilation. Building and Environment , 229 , Article 109934. 10.1016/j.buildenv.2022.109934. Green open access

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Abstract

This study proposes a new integrated air supply strategy of impinging jet ventilation (IJV) and intermittent airflow to improve indoor thermal comfort. Vertical thermal stratification is created by the IJV, and a fluctuating thermal environment is created by the intermittent airflow. Three pulsating periods (3 min, 5 min, and 7 min), two supply air temperatures (18 °C and 16 °C), and four air supply velocities (1.8 m/s steady, 1.5/2.1 m/s, 0.9/2.7 m/s, and 0/3.6 m/s) were designed. In both steady and fluctuating indoor environments, fifteen college students were asked to report their perceptions of thermal sensation, thermal comfort, thermal preference, ankle air movement acceptability and preference, and perceived air quality. The results showed that pulsating airflow could lower the mean air temperature above 0.6 m and raise it below 0.6 m. Furthermore, pulsating airflow could reduce overall and local thermal sensation by up to 0.21 and 0.28 scale unit, respectively, and the thermal sensation difference between the head and the foot by up to 0.23 scale unit. While in neutral thermal conditions, the pulsating period of 3 min had the best cooling effect of the 10 cases, but the corresponding percentage of mean dissatisfied ankle draught was 4.3% higher than in the steady operation case. Draught sensation is so closely related to ankle thermal sensation that extending the pulsating periods to 5 or 7 min could reduce ankle draught risk by up to 12.3%. The perceived air quality did not differ significantly between the steady and intermittent cases. The intermittent operation of IJV was shown to have superior cooling performance in order to improve indoor thermal comfort.

Type: Article
Title: Thermal and draught perception in fluctuating stratified thermal environments with intermittent impinging jet ventilation
Open access status: An open access version is available from UCL Discovery
DOI: 10.1016/j.buildenv.2022.109934
Publisher version: https://doi.org/10.1016/j.buildenv.2022.109934
Language: English
Additional information: This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: Thermal comfort, impinging jet ventilation, intermittent air supply, fluctuated thermal environment, draught sensation
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of the Built Environment
URI: https://discovery-pp.ucl.ac.uk/id/eprint/10162442
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