Stratified air distribution systems in a large lecture theatre: A numerical method to optimize thermal comfort and maximize energy saving

2012 ◽  
Vol 55 ◽  
pp. 515-525 ◽  
Author(s):  
Yuanda Cheng ◽  
Jianlei Niu ◽  
Naiping Gao
Keyword(s):  
Thermal Comfort ◽  
Energy Saving ◽  
Numerical Method ◽  
Distribution Systems ◽  
Air Distribution ◽  
Large Lecture ◽  
Lecture Theatre

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

Energies ◽  
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.

scholarly journals Experimental Investigation of Ventilation Performance of Different Air Distribution Systems in an Office Environment—Heating Mode

Energies ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1835 ◽  
Author(s):  
Arman Ameen ◽  
Mathias Cehlin ◽  
Ulf Larsson ◽  
Taghi Karimipanah
Keyword(s):  
Thermal Comfort ◽  
Distribution Systems ◽  
Cold Climate ◽  
Air Distribution ◽  
Temperature Pattern ◽  
Office Environment ◽  
Ventilation Effectiveness ◽  
Local Thermal Comfort ◽  
Heating Mode ◽  
Occupied Zone

A vital requirement for all-air ventilation systems are their functionality to operate both in cooling and heating mode. This article experimentally investigates two newly designed air distribution systems, corner impinging jet (CIJV) and hybrid displacement ventilation (HDV) in comparison against a mixing type air distribution system. These three different systems are examined and compared to one another to evaluate their performance based on local thermal comfort and ventilation effectiveness when operating in heating mode. The evaluated test room is an office environment with two workstations. One of the office walls, which has three windows, faces a cold climate chamber. The results show that CIJV and HDV perform similar to a mixing ventilation in terms of ventilation effectiveness close to the workstations. As for local thermal comfort evaluation, the results show a small advantage for CIJV in the occupied zone. Comparing C2-CIJV to C2-CMV the average draught rate (DR) in the occupied zone is 0.3% for C2-CIJV and 5.3% for C2-CMV with the highest difference reaching as high as 10% at the height of 1.7 m. The results indicate that these systems can perform as well as mixing ventilation when used in offices that require moderate heating. The results also show that downdraught from the windows greatly impacts on the overall airflow and temperature pattern in the room.

Energy Saving Potentials of All Cold Air Distribution System With Stratified Air Conditioning in Large Space Building

2008 ◽  
Author(s):  
Wei Bing ◽  
Li Li ◽  
Yuefen Gao ◽  
Xianliang Yang
Keyword(s):  
Energy Consumption ◽  
Energy Saving ◽  
Air Conditioning ◽  
Distribution Systems ◽  
Future Application ◽  
Air Distribution ◽  
Outdoor Air ◽  
Large Space ◽  
Cold Air ◽  
Air System

So far the energy saving potentials in refrigeration and air conditioning systems are the focuses of researchers all over the world. The all cold air distribution systems are being widely used due to the advantages of saving building space, less energy consumption in some given conditions and less initial cost, mostly in the residential or office buildings. The stratified air conditioning technology is adopted mainly for large space buildings to reduce the system energy consumption, normally at conventional supply air temperature. In this paper, with an example of large space building, the energy consumptions of four all outdoor air systems are calculated and compared from the view of the total annual primary energy consumption. The detailed analysis shows that comparing the conventional all outdoor air system for the whole indoor space or that with stratified air conditioning technology, the all cold outdoor air system with stratified air conditioning has the energy saving potentials. It will be promoted in the future application of HVAC systems in large space buildings.

CFD-Based Parametric Analysis on the Performance of Personalized Partition Air Distribution Systems

Solar Energy ◽  
2006 ◽  
Author(s):  
Kybum Jeong ◽  
Moncef Krarti ◽  
Zhiqiang Zhai
Keyword(s):  
Thermal Comfort ◽  
Air Temperature ◽  
Distribution System ◽  
Distribution Systems ◽  
Comfort Level ◽  
Cfd Modeling ◽  
Air Distribution ◽  
Air Velocity ◽  
Comfort Index ◽  
System Mode

The partition air distribution systems evaluated in this study allow occupants to control the system mode (on/off) and the supply air velocity and direction with similar flexibility as occupants in automobiles. To find optimal specifications for the partition air distribution systems that are able to achieve comfortable micro-environment, a CFD modeling tool was used to simulate the airflow and thermal performance of the partition air distribution systems in a typical office space. By analyzing the distribution characteristics of indoor air temperature, air velocity and thermal comfort index, the study assessed the performance of the partition air distribution systems with different operating parameters. The simulation results were analyzed and evaluated to assess both occupant’s thermal comfort and system energy consumption. The study shows that space cooling energy can be reduced while maintaining acceptable indoor thermal comfort level using a partition air distribution system with a higher supply air temperature.

Numerical study of different ceiling-mounted air distribution systems for a virtual classroom environment

2016 ◽  
Vol 26 (10) ◽  
pp. 1382-1396 ◽  
Author(s):  
Eusébio Z. E. Conceição ◽  
Cristina I. M. Santiago ◽  
Hazim B. Awbi
Keyword(s):  
Air Quality ◽  
Thermal Comfort ◽  
Air Temperature ◽  
Distribution Systems ◽  
Numerical Study ◽  
Virtual Classroom ◽  
Comfort Level ◽  
Air Distribution ◽  
Air Supply ◽  
Distribution Index

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℃.

scholarly journals Influence of air distribution in modern large university lecture hall on thermal comfort

2019 ◽  
Vol 10 (1) ◽  
pp. 63-69
Author(s):  
Mária Budiaková
Keyword(s):  
Thermal Comfort ◽  
Distribution System ◽  
Air Conditioning ◽  
Distribution Systems ◽  
Winter Season ◽  
Point Of View ◽  
Air Distribution ◽  
Lecture Hall ◽  
Globe Temperature ◽  
Air Conditioning Systems

The paper is focused on the influence of air distribution in modern large university lecture hall on the thermal comfort. Providing the optimal parameters of the thermal comfort in the interiors of a university is immensely important for the students. Meeting these parameters is inevitable not only from physiological point of view but also to achieve the desirable students' performance. Parameters of the thermal comfort are also influenced by air distribution system in large university lecture hall. Correct position of supply air and extract air is very important. Experimental measurements of thermal comfort were carried out in the winter season in the large lecture hall of Vienna University of Economics and Business. The device Testo 480 was used for the measurements. Obtained values of air temperature, air relative humidity, air velocity, globe temperature, indexes PMV and PPD are presented in the charts. Modern air distribution system and air conditioning system of the large university lecture hall were evaluated on the basis of thermal comfort parameters. Conclusion of this paper states the principles of how to design modern air distribution systems and air conditioning systems in the new large university lecture halls.

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