Experimental study of air distribution and heating performances of deflection ventilation

Cheng, Fanghui; Li, Yunhao; Wu, Yuxin; Cheng, Yong

doi:10.1016/j.enbuild.2023.112800

Cited by 8 publications

(3 citation statements)

References 47 publications

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“…It was highlighted that DeV could be better if the ventilation rate was increased. A similar result was also concluded by Cheng et al 50 In a recent study, Li et al 18 demonstrated the better performances of DeV and SVon anti-airborne infection at a higher ACH. They found that DeV and SV can provide better inhaled air quality and higher particle removal efficiency than MV and IJV when the ACH was 7.…”

Section: Overall Performance Analysissupporting

confidence: 83%

“…Previous studies also showed that DeV performed better at the higher supply air velocity. 40,50 For IJV, the D i values were slightly lower than SV, which was caused by the higher DR values at the ankle level. For MV, the maximum value of D i was only 0.30, indicating that it was necessary to improve energy utilization efficiency and inhaled air quality in winter.…”

Section: Overall Performance Analysismentioning

confidence: 90%

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Evaluation of heating performances of different ventilation methods in an office

Li,

Essah,

et al. 2023

Indoor and Built Environment

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In this study, 12 cases were investigated in an office-layout room using experiments and computational fluid dynamics (CFD) simulations. The heating performances of four ventilation methods (i.e. mixing ventilation (MV), stratum ventilation (SV), deflection ventilation (DeV) and impinging jet ventilation (IJV)) were comprehensively compared by various evaluation indexes (i.e. predicted mean vote (PMV), draught rate (DR), vertical air temperature difference (△T), air diffusion performance index (ADPI), energy utilization coefficient (EUC), air change efficiency (ACE) and contaminant removal efficiency (CRE)). Better thermal comfort was found in rooms heated by SV and DeV. The PMV, DR and △T under SV and DeV complied with Category B of ISO 7730:2005, and the ADPI was in full compliance with the stipulation of ANSI/ASHRAE 113-2022. For the energy-saving characteristic, the targeted-occupied-zone ventilation methods (i.e. SV, DeV and IJV) can effectively deliver warm air to the occupied zone, with the EUC values higher than unity and thus providing a good potential for energy saving. SV and IJV showed slightly higher ACEs in the breathing zone. The contaminant removal effectiveness of SV, DeV and IJV was comparable. Under the combined influence of occupant thermal plumes and locations of exhausts, MV showed a high CRE. However, the CRE under MV decreased significantly when the exhausts were not above occupants. In the case of supply air parameters in this study, the entropy-weight method indicated that DeV and SV had a better overall performance for winter heating, followed by IJV and then MV.

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Section: Overall Performance Analysissupporting

confidence: 83%

Section: Overall Performance Analysismentioning

confidence: 90%

Evaluation of heating performances of different ventilation methods in an office

Li,

Essah,

et al. 2023

Indoor and Built Environment

Self Cite

View full text Add to dashboard Cite

show abstract

“…This optimization enhanced the uniformity of airflow distribution vertically and overall thermal environment around the rack. Cheng et al (2023) have conducted experiments on deflection ventilation for winter heating. The effects of different air supply speeds, air supply temperatures and deflection angles on air distribution were analyzed, and the thermal comfort and energy efficiency were comprehensively evaluated.…”

Section: Open Accessmentioning

confidence: 99%

Influence of deflectors on indoor airflow velocity distribution under natural ventilation conditions

Wang,

Jin,

Cheng

2024

Front. Energy Res.

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Deflectors offer a cost-effective solution for enhancing airflow distribution. The purpose of this paper is to investigate the effect of the deflector on the indoor airflow velocity distribution under natural ventilation conditions. The results obtained from numerical simulations are validated through experimental measurements using a reduced-scale model. Subsequently, the validated reduced-scale numerical model was extended to full-size rooms. A full-size numerical simulation method is used to analyze the effect of no deflector, deflectors with different opening width-to-height ratios and deflectors with different opening shapes on the percentage of indoor velocity partitions under natural ventilation conditions. The findings reveal that the judicious installation of deflectors can enhance indoor airflow velocity distribution and increase the percentage of the indoor comfort zone. Deflectors with different opening width-to-height ratios exert distinct influences on indoor airflow velocity distribution. When the deflector opening width-to-height ratio is set at 7/6, the indoor comfort zone percentage reaches its maximum at 75.98%. Furthermore, the shape of the deflector’s opening significantly affects indoor airflow velocity distribution, and when the opening shape is a rhombus shape of 4.00 cm × 9.00 cm, the proportion of indoor velocity comfort zone is the largest, which is 75.56%. This study provides a reference for the design and practice of natural ventilation in buildings.

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Occupant thermal and draft perceptions under various intermittent regimes of an intermittent air jet strategy

Li,

Zhou,

Yang

et al. 2024

Building and Environment

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Experimental study of air distribution and heating performances of deflection ventilation

Cited by 8 publications

References 47 publications

Evaluation of heating performances of different ventilation methods in an office

Evaluation of heating performances of different ventilation methods in an office

Influence of deflectors on indoor airflow velocity distribution under natural ventilation conditions

Occupant thermal and draft perceptions under various intermittent regimes of an intermittent air jet strategy

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