Prediction of thermal comfort, IAQ, and energy consumption in a dense occupancy environment with the under floor air distribution system

The exhaust/return-split configuration is regarded as an important upgrade of traditional under-floor-air-distribution (UFAD) systems due to its higher energy efficiency. Moreover, existing studies are mostly focused on the effect of the return vent height on the performance of an UFAD system under cooling conditions. Knowledge of the performance under heating conditions is sorely lacking. This paper presents a numerical evaluation of the performance characteristics of an UFAD system with six different heights of the return vents in heating operation by comprehensively considering thermal comfort, air quality, and energy consumption. The results show that, in the heating mode, the general thermal comfort (predicted mean vote-predicted percentage dissatisfied (PMV-PPD) values) and indoor air quality indices (mean age of air and volatile organic compounds (VOCs) concentration) were greatly improved and energy consumption was slightly reduced with a lower return vent height. Although these were opposite to the findings of our previous study regarding the performance in cooling mode, an optimal return vent height in terms of the comprehensive all-year performance can be recommended. This method provides insight into the design and optimization of the return vent height of UFAD for space heating and cooling.

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Numerical Study on Coupled Operation of Stratified Air Distribution System and Natural Ventilation under Multi-Variable Factors in Large Space Buildings

Energies ◽

10.3390/en14238130 ◽

2021 ◽

Vol 14 (23) ◽

pp. 8130

Author(s):

Ziwen Dong ◽

Liting Zhang ◽

Yongwen Yang ◽

Qifen Li ◽

Hao Huang

Keyword(s):

Thermal Comfort ◽

Working Conditions ◽

Distribution System ◽

Distribution Systems ◽

Natural Ventilation ◽

Numerical Study ◽

Air Distribution ◽

Large Space ◽

Air Conditioners ◽

Air Supply

Stratified air distribution systems are commonly used in large space buildings. The research on the airflow organization of stratified air conditioners is deficient in terms of the analysis of multivariable factors. Moreover, studies on the coupled operation of stratified air conditioners and natural ventilation are few. In this paper, taking a Shanghai Airport Terminal departure hall for the study, air distribution and thermal comfort of the cross-section at a height of 1.6 m are simulated and compared under different working conditions, and the effect of natural ventilation coupling operation is studied. The results show that the air distribution is the most uniform and the thermal comfort is the best (predicted mean vote is 0.428, predicted percentage of dissatisfaction is 15.2%) when the working conditions are 5.9% air supply speed, 11 °C cooling temperature difference and 0° air supply angle. With the coupled operation of natural ventilation, the thermal comfort can be improved from Grade II to Grade I.

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Thermal Comfort Assessment of Underfloor vs. Overhead Air Distribution System

Journal of Applied Sciences ◽

10.3923/jas.2012.473.479 ◽

2012 ◽

Vol 12 (5) ◽

pp. 473-479 ◽

Cited By ~ 2

Author(s):

M. Aghakhani ◽

Gh. Eslami

Keyword(s):

Thermal Comfort ◽

Distribution System ◽

Air Distribution

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Operation Testing of an Advanced Personalized Ventilation System

Energies ◽

10.3390/en12091596 ◽

2019 ◽

Vol 12 (9) ◽

pp. 1596 ◽

Cited By ~ 3

Author(s):

Csáky ◽

Kalmár ◽

Kalmár

Keyword(s):

Air Quality ◽

Thermal Comfort ◽

Indoor Air Quality ◽

Indoor Air ◽

Distribution System ◽

Noise Level ◽

Background Noise ◽

Ventilation System ◽

Air Distribution ◽

Personalized Ventilation

Using personalized ventilation systems in office buildings, important energy saving might be obtained, which may improve the indoor air quality and thermal comfort sensation of occupants at the same time. In this paper, the operation testing results of an advanced personalized ventilation system are presented. Eleven different air terminal devices were analyzed. Based on the obtained air velocities and turbulence intensities, one was chosen to perform thermal comfort experiments with subjects. It was shown that, in the case of elevated indoor temperatures, the thermal comfort sensation can be improved considerably. A series of measurements were carried out in order to determine the background noise level and the noise generated by the personalized ventilation system. It was shown that further developments of the air distribution system are needed.

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