Researchers from the National Institute for Occupational Safety and Health have evaluated the relationship between flow differential and pressure differential in 67 Airborne infection isolation rooms (AIIRs) and simulated AIRR. The date collected in the simulated AIRR allowed the development of an empirical model describing the relationship between the flow differential, the pressure differential and the leakage area. The data gathered in health care facilities proved the model predicted the leakage with accuracy . That model appears as an effective and cost-cutting tool.
The Goal and the target methods are discussed in this study , they are used for balancing exhaust ventilation duct systems with dampers. For each, a detailed step-by-step procedure is presented. For the goal method, the damper is adjusted in each branch until the airflow for each branch equals the goal airflow : it is time consuming and the overall resistance of the system increases, reducing the fan output. Concerning the target method, simulations predict a better accuracy for fewer adjustments than the goal method, but it is more computationally difficult.
For that study , measurements of carbon dioxide and ultrafine particles were carried out in four restaurants located in 2 different cities in northwest Ohio. In each city, one restaurant was smoke free and the other one had a dedicated smoking room. A smoke free office space was assessed as a reference site. The results of the measurements show that C02 levels were elevated in all 4 restaurants with an inadequate fresh air supply.
For that paper, a case study was conducted to compare the performance of two control methods in an office environment : conventional setpoint control and predicted mean vote (PMV) based control. To obtain the thermal environments created by the two control methods, computer simulations have been used. The results show that the conventional control caused a reduction in human productivity whereas the PMV control performed well for both human comfort and human productivity.
For the experiment detailed airflow fields were measured in three cases of ventilation air temperature : an isothermal case, a hot case and a cold case.The experimental data have been used to test four two equations turbulence models. And it appears that none of the models is reliable concerning the cold case whereas they all can predict reasonably the hot and isothermal cases global values of temperature and velocity. Those models are not able to predict the exact experimental velocity and temperature fields.
The numerical simulation results of the stack effect in medium-rise buildings in Harbin (cold region in China) are presented in that paper. The multizone ventilation model COMIS was used for the simulation. The effect of the wind speed velocity and the temperature of the stairwell on the pressure difference curves shape have been investigated. It appears that the wind speed velocity may have a strong effect on the pressure difference.
The aim of that research is to obtain contaminant concentrations in a room, to perform qualitative and quantitative comparison for a wall jet air inlet and a ceiling diffuser air inlet, and to determine more efficient inlet and outlet configuration. The effect of air inlet types in mixing ventilation was investigated in an experimental room under two conditions, with no occupant and with an occupant present north of the source. The results have shown that the air inlet type is an important physical determinant to the distribution of airborne contaminant concentrations.
How the contaminants disperse in a personalized ventilation room has to be studied carefully in so far the contaminant distribution determines IAQ. This paper deals with the investigation by CFD of the dispersion of particles in a room ventilated by a personalized ventilation system. In that aim a three-dimensional model is employed, airflow and temperature distribution is simulated after experimental validation. The results of the different simulations are presented.
The indoor air quality is influenced in the long term by the chemical contaminants emitted by dried building material. The aim of this paper is to simulate the indoor total volatile organic compounds (TVOCs) distribution emitted from a new floor along with the total TVOCs quantity inhaled by an occupant with the different fresh air ratios under a re-circulated ventilation system. The simulation results and analysis are a great help to design the indoor healthy occupant environment and to improve some features of the re-circulated ventilation system.
One of the common approaches for assessing indoor pollutant level is the continuous sampling. Alternative sampling schemes taking shorter measurements were proposed. For that study a year round indoor CO2 concentration at 17 locations in a typical office in Hong Kong was used to evaluate the probable errors using four sampling schemes :
A - a continuous sampling throughout the measurement
B - 2 sampling periods of 2 equal sessions of the measurement
C - 2 structural sampling periods of the 2 sessions of the measurement
Login