Numerical and experimental analysis of the air stream generated by square ceiling diffusers

Marek Jaszczur,Marcin Zych,Slawosz Kleszcz,Patryk Palej,Pawel Madejski,A Mohamad,J Taler,A.C Benim,G Battista,A Vallati,R Bennacer,R De Lieto Vollaro,S.-H Suh

doi:10.1051/e3sconf/201912808003

Abstract

Ceiling diffusers are one of the most important elements of ventilation and air-conditioning installations. They have a significant impact on the speed and temperature distribution of air. The basic task of these devices is to provide the required air stream while maintaining its appropriate parameters in the occupied zone and low noise levels in the room. Square ceiling diffusers are designed for use in low- and medium-pressure ventilation systems. The diffusers allow obtaining 1, 2, 3 or 4-way air supply. Knowledge of the airflow formed by the diffuser is essential in order to ensure the comfort of people staying in a ventilated room. Designers of the diffusers nowadays mainly use advanced software and CFD (Computational Fluid Dynamics) modelling technique. CFD methods allow to quickly analyse the fluid flow. However, an very important problem is the consistency of the results obtained by numerical methods with the results obtained on an experimental way. The work presents a laboratory stand designed to test ceiling diffusers. In this research study the single square ceiling diffuser was experimentally and numerically analysed.

Highlights

Ventilation of buildings is aimed at ensuring the adequate air quality in rooms
The ventilation system is designed to bring the proper amount of air and ensure the desired air distribution inside the rooms
Knowledge and forecasts regarding the flow of indoor air streams are important

Summary

INTRODUCTION

Ventilation of buildings is aimed at ensuring the adequate air quality in rooms. The ventilation system is designed to bring the proper amount of air and ensure the desired air distribution inside the rooms. The diffusers of this type are widely used in supply and exhaust systems in rooms requiring comfort, such as offices, shopping centres, restaurants, cinemas or so-called "clean rooms" [4, 5] When selecting this type of diffusers, an important issue is to determine the range zone of the air stream. For the channel flows DNS [8] and LES [9] provide very accurate results but for the large areas this methods are still beyond practical applications It can be noticed, that there are significant discrepancies between the data of the different air producers in determining the range of the supply air stream. This system enables multi-point measurements of air velocity and temperature It is used, inter alia, to assess thermal conditions and the speed distribution in rooms. Its uncertainty of measurement is ± 0.02 m/s ± 1.5%

RESULTS

NUMERICAL ANALYSIS

CONCLUSIONS