Directional airflow performance of ventilators for natural ventilation

The use of natural ventilation systems continues to be a popular feature in low energy, sustainable building design. One feature of natural ventilation is that, depending upon the prevailing climatic or thermal conditions, the airflow through a ventilator can be bi-directional. Aerodynamically, the ventilator, depending upon its construction, may not perform in the same way for the two different flow directions.

Ventilation calculation by network model inducing bi-directional flows in openings

For the multi-room ventilation calculations, bi-directional flows or counter flows in openings have been rarely taken into consideration and only uni-directional flows have been allowed for the calculation. It stands to reason that the calculation requires quite sophisticated scheme and the appearance of the bi-directional flows are restricted only to a limited number of openings neighboring the neutral plane of the building and also the flow rates may be too little to affect the total building

Time varying linear model approximation : application to thermal and airflow building simulation

Considering the natural ventilation, the thermal behavior of buildings can be described by a linear time varying model. In this paper, we describe an implementation of model reduction of linear time varying systems. We show the consequences of the model reduction on computing time and accuracy. Finally, we compare experimental measures and simulation results using the initial model or the reduced model.

Optimization of airflow regimes, energy efficiency, and air quality in surgical operating theatres.

The present paper addresses and fosters the factors that affect airflow movement and energy efficiencies in the surgical operating theatres. The present work puts forward analyses for major factors contributing to failure to achieve and attain the optimum Indoor Air Quality (IAQ), and the methods suggested to solve such problem. Appropriate architectural and mechanical engineering recommendations to achieve the optimum hygienic operating theatre are set out in the paper.

A new method of CFD simulation of airflow characteristics of swirling floor diffusers

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.

Development of a guideline for selecting a simulation tool for airflow prediction

With the advancement of technology, and with the widespread availability of simulation tools, we are forced to consider which simulation tool would be appropriate for a particular problem. The seemingly trivial decision is in reality not very easy to make. And this leads to the practice of using the most sophisticated tool available for every problem. The levels of resolution and complexity are directly related to the accuracy of the simulation and to the total cost of the simulation process. A simple tool may be cheaper, but there is a high risk of inaccuracy.

Validation of CONTAMW predictions for tracer gas in a townhouse

To provide additional validation data for the multizone airflow and contaminant model, CONTAMW, experiments were performed in an occupied 3-story townhouse in Reston, VA. A tracer gas, sulfur hexaflouride (SF6), was manually injected within one room of the house and the concentration of SF6 was measured in each zone. This same process was then recreated in CONTAMW and the resulting predictions were statistically compared to the measured values. A total of 10 experiments were conducted and simulated between May 2000 and June 2001.

TRNFLOW, a new tool for the modelling of heat, air and pollutant transport in building within TRNSYS

Modelling of buildings with natural or hybrid ventilation systems requires the coupling of a thermal and an air flow model because of the strong mutual impact of the thermal and the air flow behaviour. The newly developed tool TRNFlow is the complete integration of the multizone air flow and pollutant transport model COMIS [Dorer 2001] into the thermal multizone building module of the building and system simulation program TRNSYS [Klein 2000]. An internal solver algorithm using

SIM_zonal : a software to evaluate the risk of discomfort : coupling with an energy engine, comparison with CFD codes and experimental measurements

The software Sim_Zonal is a tool for evaluating indoor temperature and air flow distributions for residential and office buildings. The aim of this EDF (Electricity of France) software developed in collaboration with LEPTAB (University of La Rochelle) is to evaluate comfort problems and specifically risks of discomfort (risk of draught, indoor gradient temperature, etc..) with taking

Control of ventilation in buildings using Simbad building and HVAC toolbox

There is a growing need for more complex control of ventilation systems to satisfy energy and environmental issues. SIMBAD Toolbox (SIMulator of Buildings And Devices), developed in the SIMULINK graphical environment is a library of HVAC components models that is used in the field of