An Air Distribution Index for Assessing the Thermal Comfort and Air Quality in Uniform and Nonuniform Thermal Environments

This paper presents a comparative numerical study of different ceiling-mounted-localized air distribution systems placed above students in a virtual classroom in summer conditions. The influence of four different ceiling-mounted-localized air distribution systems, using vertical descendent jets, on the thermal comfort, local thermal discomfort, and air quality levels was numerically evaluated. The air distribution index, developed previously, was used for non-uniform environment. This index considers the thermal comfort level, air quality level, effectiveness for heat removal, and effectiveness for contaminant removal. Numerical simulations were conducted for a virtual classroom equipped with one of four different ceiling-mounted-localized air distribution systems and with 6 desks, 6 or 12 students, and 2 upper airflow outlets. Inlet air supply temperature of 20 and 24℃ and an outdoor air temperature of 28℃ were used. The simulation results show that the air supply system having a vertical air jet placed at 1.8 m above the floor level (Case III), and with an inlet area of 0.01 m2 and a supply air velocity of 3 m/s would represent the best option in comparison with other air supply methods. In general, the air distribution index value decreases with an increase in inlet air temperature and the number of occupants. The air distribution index values are highest for Case III representing a classroom with 6 or 12 occupants with an inlet air temperature of 20 or 24℃.

Download Full-text

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.

Download Full-text

Evaluation of Integral Effect of Thermal Comfort, Air Quality and Draught Risk for Desks Equipped with Personalized Ventilation Systems

Energies ◽

10.3390/en14113235 ◽

2021 ◽

Vol 14 (11) ◽

pp. 3235

Author(s):

Eusébio Conceição ◽

Hazim Awbi

Keyword(s):

Air Quality ◽

Thermal Comfort ◽

Numerical Study ◽

Heat Removal ◽

Thermal Conditions ◽

Air Distribution ◽

Pv Systems ◽

Integral Effect ◽

Personalized Ventilation ◽

Air Removal

This work evaluates the integral effect of thermal comfort (TC), indoor air quality (IAQ) and Draught Risk (DR) for desks with four personalized ventilation (PV) systems. The numerical study, for winter and summer thermal conditions, considers a virtual chamber, a desk, four different PV systems, four seats and four virtual manikins. Two different PV configurations, two upper and two lower air terminal devices (ATD) with different distance between them are considered. In this study a coupling of numerical methodology, using one differential and two integral models, is used. The heating, ventilating and air conditioning (HVAC) system performance in this work is evaluated using DR and room air removal effectiveness (εDR) that is incorporated in an Air Distribution Index (ADI). This new index, named the Air Distribution Turbulence Index (ADTI), is used to consider simultaneously the TC, the IAQ, the DR and the effectiveness for heat removal (εTC), contaminant removal (εAQ) and room air removal (εDR). The results show that the ADI and ADTI, are generally higher for Case II than for Case I, increase when the inlet air velocity increases, are higher when the exit air is located at a height 1.2 m than when is located at 1.8 m, and are higher for summer conditions than for winter conditions. However, the values are higher for the ADI than ADTI.

Download Full-text

Innovative Rear Air Blower Design Application for Improving Cabin Thermal Comfort with Improved Air Distribution and Air Quality

10.4271/2020-28-0034 ◽

2020 ◽

Author(s):

Ravi Garg ◽

Suraj maske ◽

Yogendra Singh Kushwah

Keyword(s):

Air Quality ◽

Thermal Comfort ◽

Air Distribution ◽

Air Blower

Download Full-text

Effects of return air vent height on energy consumption, thermal comfort conditions and indoor air quality in an under floor air distribution system

Energy and Buildings ◽

10.1016/j.enbuild.2015.04.004 ◽

2015 ◽

Vol 97 ◽

pp. 155-161 ◽

Cited By ~ 16

Author(s):

Ghassem Heidarinejad ◽

Mohammad Hassan Fathollahzadeh ◽

Hadi Pasdarshahri

Keyword(s):

Energy Consumption ◽

Air Quality ◽

Thermal Comfort ◽

Indoor Air Quality ◽

Indoor Air ◽

Distribution System ◽

Air Distribution ◽

Air Vent

Download Full-text

Numerical Study on Effects of Air Return Height on Performance of an Underfloor Air Distribution System for Heating and Cooling

Energies ◽

10.3390/en13051070 ◽

2020 ◽

Vol 13 (5) ◽

pp. 1070

Author(s):

Yaming Fan ◽

Xiangdong Li ◽

Minfeng Zheng ◽

Rengui Weng ◽

Jiyuan Tu

Keyword(s):

Energy Consumption ◽

Air Quality ◽

Thermal Comfort ◽

Distribution System ◽

Numerical Study ◽

Air Distribution ◽

Cooling Mode ◽

Design And Optimization ◽

Heating And Cooling ◽

Heating Mode

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.

Download Full-text

Moderate thermal environments. Determination of the PMV and PPD indices and specification of the conditions for thermal comfort

10.3403/00814151u ◽

2015 ◽

Cited By ~ 19

Keyword(s):

Thermal Comfort ◽

Thermal Environments

Download Full-text

Real-time determination of optimal indoor-air condition for thermal comfort, air quality and efficient energy usage

Energy and Buildings ◽

10.1016/j.enbuild.2004.01.017 ◽

2004 ◽

Vol 36 (7) ◽

pp. 720-733 ◽

Cited By ~ 64

Author(s):

S Atthajariyakul ◽

T Leephakpreeda

Keyword(s):

Air Quality ◽

Thermal Comfort ◽

Real Time ◽

Indoor Air ◽

Energy Usage ◽

Efficient Energy ◽

Time Determination

Download Full-text

Performance Evaluation of Particulate Matter and Indoor Microclimate Monitors in University Classrooms under COVID-19 Restrictions

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18147363 ◽

2021 ◽

Vol 18 (14) ◽

pp. 7363

Author(s):

Laurentiu Predescu ◽

Daniel Dunea

Keyword(s):

Performance Evaluation ◽

Particulate Matter ◽

Air Quality ◽

Indoor Environment ◽

Indoor Environments ◽

University Campus ◽

Particle Counter ◽

Thermal Environments ◽

University Classrooms ◽

Academic Personnel

Optical monitors have proven their versatility into the studies of air quality in the workplace and indoor environments. The current study aimed to perform a screening of the indoor environment regarding the presence of various fractions of particulate matter (PM) and the specific thermal microclimate in a classroom occupied with students in March 2019 (before COVID-19 pandemic) and in March 2021 (during pandemic) at Valahia University Campus, Targoviste, Romania. The objectives were to assess the potential exposure of students and academic personnel to PM and to observe the performances of various sensors and monitors (particle counter, PM monitors, and indoor microclimate sensors). PM1 ranged between 29 and 41 μg m−3 and PM10 ranged between 30 and 42 μg m−3. It was observed that the particles belonged mostly to fine and submicrometric fractions in acceptable thermal environments according to the PPD and PMV indices. The particle counter recorded preponderantly 0.3, 0.5, and 1.0 micron categories. The average acute dose rate was estimated as 6.58 × 10−4 mg/kg-day (CV = 14.3%) for the 20–40 years range. Wearing masks may influence the indoor microclimate and PM levels but additional experiments should be performed at a finer scale.

Download Full-text