Indoor Environment Numerical Simulation of All Cold Air Distribution System With Stratified Air Conditioning

2008 ◽  
Author(s):  
Wei Bing ◽  
Li Li ◽  
Jiang Lu ◽  
Zhang Wei
Keyword(s):  
Numerical Simulation ◽  
Distribution System ◽  
Air Conditioning ◽  
Distribution Systems ◽  
Dew Point ◽  
Air Distribution ◽  
Large Space ◽  
Cold Air ◽  
Point Temperature ◽  
Dew Point Temperature

At present all cold air distribution systems are being used widely due to their advantages of smaller ductwork, shorter floor-to-floor height and less energy consumption etc. They are mostly used in VAV (Variable Air Volume) systems or with the radiant panel systems in the office and residential buildings at the supply air dew point temperature of 6∼10°C, rarely used in large space buildings. The technology of stratified air conditioning is one of the energy saving technologies to large space buildings, which has been popularly used in the conventional air supply systems with the supply air dew point temperature of 11∼16°C. In this paper, the cold air distribution system and the stratified air conditioning technology in a large space building are combined to study. With the method of CFD, the indoor thermal environment of a large space workshop is simulated. The velocity and the temperature as well as the relative humidity fields under different air flow modes are presented, analyzed and compared. With the help of numerical simulation results, the optimal airflow mode is proposed, which show that the all cold air distribution with the stratified air conditioning is a good option for large space buildings. All these above will be good references to the application of cold air distribution system and the selection of the airflow mode in large space buildings.

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.

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.

Evaluation of membrane-based air pre-dehumidification for a capillary radiant air conditioning system

2020 ◽  
pp. 1420326X2096738
Author(s):  
Zan-She Wang ◽  
Fang-Ting Yin ◽  
Ran Li ◽  
Zhao-Lin Gu
Keyword(s):  
Moisture Content ◽  
Air Conditioning ◽  
Dew Point ◽  
Liquid Desiccant ◽  
Air Conditioning System ◽  
Point Temperature ◽  
Dew Point Temperature ◽  
Temperature Range ◽  
Libr Solution ◽  
The Ideal

The polyvinylidene fluoride hollow fibre membrane air dehumidification tests were carried out between the liquid desiccant solutions and the wet air. Three liquid desiccant solutions of LiBr solution (50%), LiCl solution (35%) and CaCl2 solution (40%) were tested under different wet air conditions. The results showed that all the membrane dehumidification processes were stable. The air moisture content in the outlet of the membrane was maintained as 6.5 g/kg (da)–8.2 g/kg (da) when the air moisture content in the inlet of the membrane was operated from 17.1 g/kg (da) to 32.4 g/kg (da). The dehumidification amount of LiBr solution (50%) and LiCl solution (35%) was more productive. On this basis, a membrane-based air pre-dehumidification process for the capillary radiant air conditioning system was built. Since the ideal dew point temperature range of the indoor air is below 14–17°C according to the cold supply water, all the air moisture content at the membrane outlet is much lower than that of the ideal dew point temperature range, which means non-condensing occurs in the capillary tube surface. The membrane-based air pre-dehumidification process can easily form an adaptive regulation process of humidity with the capillary radiant air conditioning system under different environmental parameters.

Numerical Simulation Analysis of Cold Air Distribution System

2016 ◽  
Vol 858 ◽  
pp. 278-281
Author(s):  
Cheng Cai Sun ◽  
Bo Zhou ◽  
Jie Lv
Keyword(s):  
Numerical Simulation ◽  
Physical Model ◽  
Distribution System ◽  
Simulation Analysis ◽  
Three Dimensional ◽  
Simulation Method ◽  
Air Distribution ◽  
Indoor Airflow ◽  
Cold Air ◽  
Fluent Software

This paper based on an actual project as an example, researching the application of cold air distribution system by using the numerical simulation method. By using Fluent software to establish a three-dimensional physical model, simplificate the physical model, establish proper tuyere model, choose the appropriate turbulence model, select the appropriate boundary conditions. Then simulate indoor airflow organization, get the distribution of temperature field, velocity field in the working area, and evaluate the comfort in the working area. Though the research, this paper provides the appropriate air distribution which is the upper supply air and on opposite side bottom exhaust air. This paper though the numerical simulation concludes that adopts the appropriate air distribution could meet the requirements of indoor thermal comfort.

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.

scholarly journals Experimental Study on Indoor Thermal Stratification in Large Space by under Floor Air Distribution System (UFAD) in Summer

Engineering ◽  
2011 ◽  
Vol 03 (04) ◽  
pp. 384-388 ◽  
Author(s):  
Xin Wang ◽  
Chen Huang ◽  
Weiwu Cao ◽  
Xuelei Gao ◽  
Wen Liu
Keyword(s):  
Experimental Study ◽  
Distribution System ◽  
Thermal Stratification ◽  
Air Distribution ◽  
Large Space

scholarly journals Some Aspects of HVAC Design in Energy Renovation of Buildings

2021 ◽  
Author(s):  
Taghi Karimipanah
Keyword(s):  
Renewable Energy ◽  
Air Conditioning ◽  
Distribution Systems ◽  
Energy System ◽  
Building Energy ◽  
Hvac Systems ◽  
Heat Losses ◽  
Energy Sources ◽  
Air Distribution ◽  
Building Energy System

It is well-known fact that air conditioning systems are responsible for a significant part of all energy systems in building energy usage. In EU buildings, the building HVAC systems account for ca 50% of the energy consumed. In the U.S., air-conditioning accounts on average about 12% of residential energy expenditures. The proper choice of air distribution systems and sustainable energy sources to drive the electrical components have a vital impact to achieve the best requirements for indoor climate including, hygienical, thermal, and reasonable energy-saving goals. The building energy system components that have a considerable impact on the demand for final energy in the building are design, outdoor environment conditions, HVAC systems, water consumption, electrical appliances, indoor thermal comfort, and indoor human activities. For calculation of the energy balance in a building, we need to consider the total energy flows in and out from the building including ventilation heat losses, the perimeters transmission heat loses, solar radiation, internal heat from occupants and appliances, space and domestic water heating, air leakage, and sewage heat losses. However, it is a difficult task to handle the above time-dependent parameters therefore an energy simulation program will always be used. This chapter aims to assess the role of ventilation and air-conditioning of buildings through the sustainability approaches and some of the existing renewable energy-based methods of HVAC systems are presented. This comprehensive review has been shown that using the new air distribution systems in combination with renewable energy sources are key factors to improve the HVAC performance and move toward Nearly Zero Carbon Buildings (NZCB).

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