Application Study of Cold Air Distribution System

2013 ◽  
Vol 732-733 ◽  
pp. 548-551 ◽  
Author(s):  
Xiao Ming Zhang ◽  
Cheng Cai Sun ◽  
Xiao Zhang ◽  
Ji Zhi Li
Keyword(s):  
Distribution System ◽  
Thermal Environment ◽  
Simulation Software ◽  
Air Distribution ◽  
Paper Briefly ◽  
Application Study ◽  
Cold Air ◽  
Indoor Thermal Comfort ◽  
Air Supply ◽  
Air Diffusion

This paper briefly introduced the cold air distribution system principle and characteristics. Apply the simulation software to simulate air distribution and thermal environment of cold air supply room. Adopt Effective Draft Temperature (EDT) and Air Diffusion Performance Index (ADPI) to evaluate indoor thermal comfort.

Assessment of thermal comfort in high-occupancy spaces with relevance to air distribution schemes: A case study of mosques

2018 ◽  
Vol 39 (5) ◽  
pp. 572-589 ◽  
Author(s):  
S Samiuddin ◽  
Ismail M Budaiwi
Keyword(s):  
Thermal Comfort ◽  
Performance Index ◽  
Distribution System ◽  
Thermal Environment ◽  
Terminal Velocity ◽  
Air Distribution ◽  
Human Thermal Comfort ◽  
Index Value ◽  
Air Diffusion

In high-occupancy intermittently operated buildings such as mosques and auditoriums, maintaining an acceptable thermal environment may present a challenging task. Variations in the operation and the thermal loads can result in variable and non-uniform thermal comfort conditions when the HVAC system is not properly designed. Non-uniformity of the thermal environment is greatly influenced by the design and scheme of the air distribution system. Mosques, with their distinctive five intermittent short occupancies and the non-fixed posture of occupants, present a unique case for investigation. In this study, the effect of air distribution of various schemes of a ceiling-based system on the thermal comfort in mosques is investigated. Air diffusion performance index and Fanger’s PMV method are used to assess thermal comfort. Three air distribution schemes at four diffuser terminal velocities were studied using the EnergyPlus and computational fluid dynamics techniques. Results indicate major variations in air diffusion performance index with each air distribution scheme type and diffuser terminal velocity. The uniformity of the PMV was entirely dependent on the air diffusion performance index value and exhibited large variations when the air diffusion performance index value was low. In most cases, the space was overcooled with an average PMV of −0.66 or below. Practical application: The effect of air distribution system design on human thermal comfort has been very complex to understand, as it involves different schemes and different diffuser discharge velocities. This study will help engineers and designers in designing better thermal environment for the occupants.

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.

Quantitative investigations on setting parameters of air conditioning (air-supply speed and temperature) in ventilated cooling rooms

2019 ◽  
Vol 30 (1) ◽  
pp. 99-113 ◽  
Author(s):  
Haofu Chen ◽  
Zhuangbo Feng ◽  
Shi-Jie Cao
Keyword(s):  
Thermal Comfort ◽  
Air Conditioning ◽  
Thermal Environment ◽  
Inertial Force ◽  
Index Formula ◽  
Design Parameters ◽  
Dimensionless Number ◽  
Indoor Thermal Environment ◽  
Indoor Thermal Comfort ◽  
Air Supply

Rational and scientific design of indoor air conditioning is essential. In the design of Heating, Ventilating and Air Conditioning system, air-supply speed (ventilation rate) and air-supply temperature are the two most important parameters. In the current study, numerical simulations and experimental measurements were adopted to investigate the influences of ventilation mode, air-supply velocity and air-supply temperature on indoor thermal comfort as well as building energy consumption in summer. Different ventilation modes (up supply and down exit, ceiling supply and ceiling exit) were considered in modelling. Based on the simulation and experimental results, dimensionless index [Formula: see text] is proposed, which represents the ratio of buoyancy weighting force to inertial force. This index can be used as a pre-evaluation index of indoor thermal comfort in preliminary design of air conditioning. It is an indicator to judge the working conditions in cooling-ventilated rooms. When [Formula: see text], the settlement and diffusion effects of indoor airflow reach a good level, which means that the parameter setting could provide a comfortable indoor thermal environment. The dimensionless number [Formula: see text] is a theoretically based tool in the pre-evaluation of indoor thermal environment, providing guidance for setting of ventilation design parameters.

A Study on Evaluation of ADPI and Ventilation Performance of a Small Auditorium with Unevenly Arranged Return Diffusers

2017 ◽  
Vol 25 (04) ◽  
pp. 1750029
Author(s):  
Yong-il Kwon
Keyword(s):  
Distribution System ◽  
Distribution Systems ◽  
Numerical Study ◽  
Side Wall ◽  
Air Distribution ◽  
Rear Wall ◽  
System Parameters ◽  
Ventilation Efficiency ◽  
Ventilation Performance ◽  
Air Diffusion

The ventilation performance and thermal comfort characteristics on placing the supply or return diffusers for the air distribution systems applied to an auditorium with high ceiling heights must be inherently considered. A numerical study has been conducted to simulate the airflow and ventilation characteristics in a small auditorium with the uniformly installed supply diffusers on the ceiling surface, and with the unevenly installed return diffusers on the side wall of the stage, the left and rear wall. It is the objective of the present study to investigate the effects of various air distribution system parameters on air diffusion performance index (ADPI), air change efficiency and scale of ventilation efficiency NO.4 (SVE4) of return diffusers in the auditorium with the movable audience seat on the flat floor. This paper focuses mainly on the effect of the unevenly installed return diffusers on the low part of the side wall of the auditorium with the movable audience seat.

scholarly journals Effect of supply air temperature on conservation of energy in air conditioning of space

2011 ◽  
pp. 51-54
Author(s):  
V. N. Bartari ◽  
S. P. S. Rajput
Keyword(s):  
Air Temperature ◽  
Distribution System ◽  
Energy Savings ◽  
Thermal Environment ◽  
Temperature Sensors ◽  
Air Distribution ◽  
Conservation Of Energy ◽  
Buoyancy Flow ◽  
Flow Energy ◽  
The Impact

In HVAC applications, huge amount of energy is utilized in fans and blowers to maintain the flow. In this paper energy savings associated with air distribution is discussed. In a most commonly used air distribution system, uniform thermal environment in the occupied space is established. An alternative to this method is the under floor air distribution system (UFAD) which is in its fantasy state. Thermal stratification can be established in this method due to the buoyancy flow of the air. In this paper assessment of the impact of temperature sensors in energy savings is done in UFAD system. It is observed that by the placement of temperature sensors in the occupied space, supply air temperature can be controlled while maintaining the comfort conditions. By optimal conditions of the temperature and volume flow, energy savings can be achieved due to reduction in energy requirements in refrigeration and ventilation. The comfort criteria of ASHRAE standard 55-92 is taken.

A sustainable localised air distribution system for enhancing thermal environment and indoor air quality of poultry house for semiarid region

2021 ◽  
Vol 203 ◽  
pp. 70-92
Author(s):  
Douaa K. Al Assaad ◽  
Mohamad S. Orabi ◽  
Nesreen K. Ghaddar ◽  
Kamel F. Ghali ◽  
Darine A. Salam ◽  
...  
Keyword(s):  
Air Quality ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Distribution System ◽  
Thermal Environment ◽  
Air Distribution ◽  
Semiarid Region ◽  
Poultry House

Numerical Simulation on Effects of Air Supply Angle and Air Supply Velocity to Indoor Thermal Environment of Wall Hanging Air-Conditioning

2014 ◽  
Vol 1030-1032 ◽  
pp. 553-557
Author(s):  
Xiao Yong Peng ◽  
Lan Xia Guo ◽  
Xu Sheng Chai ◽  
Jing Jing Liang ◽  
Zhi Qiu Fu
Keyword(s):  
Air Conditioning ◽  
Thermal Environment ◽  
Temperature Fields ◽  
Air Distribution ◽  
Supply Angle ◽  
Air Supply ◽  
Supply Condition ◽  
Comprehensive Comparison ◽  
The One ◽  
Supply Velocity

A wall hanging air-conditioning office was simulated on three different air supply angle and three different air supply velocity by the AIRPAK .Based on the velocity fields, temperature fields, PMV-PPD obtained, analysis indoor thermal comfort. The result shows obvious difference of air distribution and great effect of indoor thermal under different air supply angle and different air supply velocity. By comprehensive comparison, the best air supply condition is the one of 75° downward, 3.0m/s.

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.

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