diffusion

Klima ADE is a program for fast selection and calculation of air diffusion devices, which isbased on:- Design criteria for the thermal environment are based on EN ISO 7730 (optimaloperative temperature and maximum mean air velocity in occupied zone).

Two air terminal devices (ATD) for personalized ventilation (PV) were developed: RoundMovable Panel (RMP) and Headset-Incorporated Supply (Headset). The performance of theATDs was tested at three combinations of room air temperature and supply personalized airtemperature: 23/23C, 23/20C and 26/20C, respectively, and at different flow rates ofpersonalized air, ranging from 5 to 15 l/s for RMP and from 0.18 to 0.5 l/s for Headset. Abreathing thermal manikin was used to evaluate the inhaled air quality achieved with thedeveloped ATDs as well as the performance in regard to thermal comfort.

Whilst Computational Fluid Dynamics (CFD) has been popularly applied in indoor air andventilation research, most Personalized Ventilation (PV) research is based on experiments.This study is an attempt to seek validation of PV experimental data with results fromnumerical models of Air Terminal Device (ATD), since the ATD is crucial in the simulation ofPV system.The CFD study involves a systemic study and comparison of various simulation methods ofPV ATD, aimed to develop PV ATD models for future whole room PV system simulation.Boundary Conditions (BC) are obtained from an elaborate set of me

Air supply diffusers used in air-conditioning systems can be classified as ceiling diffusers,side-wall diffusers, floor diffusers, jet nozzles and low velocity displacement diffusers. Fixedor adjustable slats are usually used to control airflow directions. Recently, swirling vanes areused in floor diffusers to create a swirling out-flow jet, so that more rapid mixing withambient air can be achieved.

This paper describes the unsteady terminal and presents its characteristics gained fromexperiment. The experimental results showed that the fan-coil unit tested in the experimentwas able to provide fluctuating airflow and the velocity curve of supply airflow wasconsistent with the control signal very well. The spectrum of supply airflow is similar to thespectrum of natural wind if the control signal simulating natural wind provided. The supplyair temperature is changed when the airflow is changed.

Currently, a design of the maximum velocity stress in the occupied zone is based on applicationof the jet theory equations or on the data from the manufacturers catalogue. However, thesemethods are based on the idealized test conditions in empty rooms and do not necessarily predictthe conditions existing in realistic rooms with heat sources and sinks. Furthermore, little data isavailable of the distributions inside the occupied zone. A new statistical method for occupiedzone maximum velocity prediction is introduced and verified using experimental data.

Particle diffusion with gravitational sedimentation in displacement and mixing ventilated rooms is investigated numerically. The drift flux model, which considers the settling of particles under the effect of gravitational sedimentation, is adopted to simulate particle diffusion, while the simplified
model for solving the continuous fluid flow is combined. Since the PM 2.5 and PM 10 particles are mostly concerned in indoor environment, passive contaminant and 2.5-20 micron particles are investigated in this paper. The numerical results show that in a mixing ventilated room, the

Air supply diffusers used in air-conditioning systems can be classified as ceiling diffusers, sidewall diffusers, floor diffusers, jet nozzles, and low velocity displacement diffusers. Fixed or adjustable slats are usually used to control airflow directions.

One of the major means of air diffusion for air conditioning equipment is the displacement ventilation. The stack effect is used by introducing at a very low speed, in the lower part of the room, some air whose temperature is close to the one of the desired atmosphere.

The author points out the importance of a good selection of the dimensions of swirl air diffusers, using data provided by the manufacturers. It also gives information about the method for deciding of their number and position in the room.