This, in turn, creates a significant buoyancy effect. The difference in humidity levels leads to the change in density of the air. In this situation, high mixing takes place, which enhances the dispersion effect of the contaminant.
Small fluctuations become amplified, creating unstable flow and finally becoming turbulent. MovementĬontaminant dispersion and indoor air quality are also affected by movement, for example:Īs the characteristic Reynolds number of the flow increases, the flow does not remain streamline. These air leaks impact the flow pattern in the indoor space which in turn affects the contamination dispersion and overall IAQ. This infiltration can have a drastic effect on heat loss, especially in the winter. Small cracks around windows, walls or doors, can allow the air to leak, allowing infiltration into and out of the indoor space. Heat gains from equipment, e.g., computers and lights.Sensible and latent heat gains from occupants.Radiation between solid surfaces within the room.Transmission of heat by conduction through solid surfaces such as walls, ceiling, and floors.The main heat sources or sinks in rooms include the following : Volatile organic compounds (VOC’s) (organic species from building material and finishes to cleaning agents and solvents).Carbon monoxide (tobacco smoking, incomplete combustion of hydrocarbons, and improperly ventilated heating or cooking appliances).Carbon dioxide (exhaled by-product of all mammalian metabolism).There are several contaminant sources that should be considered when analyzing the targeted zone. CFD simulations play a vital role in reducing the dispersion of contaminants in the indoor environment. There are many sources of contaminant dispersion which can directly affect the IAQ. Indoor Air Quality Sources of Contaminant Dispersion Affecting Indoor Air Quality (IAQ) This reduces the cost and time required for the experimental testing, resulting in a more efficient design process and smarter decisions. This virtual design phase allows optimal conditions to be identified for a thermally comfortable, healthy, and energy efficient building before it gets to the construction phase. CFD facilitates the accurate simulation of various indoor models simply by changing the location of the heating or air conditioning units and diffuser types. These parameters can include the thermal and ventilation analysis of the indoor systems.
In various heating, ventilation, and air conditioning (HVAC) systems, CFD can be used to determine which parameters will have the largest impact in relation to improving the IAQ, or indoor air quality, and living conditions. CFD now plays an important role in accurately simulating the indoor airflow, helping building design engineers to improve the indoor air quality without compromising on low energy consumption. With the advent of computer-aided engineering (CAE), advanced tools-particularly CFD-have become the principal method to quickly and effectively resolve these issues. In the early days of construction, wind tunnel tests were the standard method for investigating the indoor air quality (IAQ) of industrial and commercial buildings, hospitals or laboratories.
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