Modelling of volatile organic compounds concentrations in rooms due to electronic devices

Abstract The objective of this study is to develop an approach concerning the integration of volatile organic compounds (VOCs) emissions due to office equipment in computational fluid dynamics (CFD) simulations, in order to assess the indoor air quality (IAQ). The transport and diffusion phenomena of VOCs are taking into account in the CFD model by means of conservation equations of the mass fraction, written for each VOC that is intended to be considered in the simulation. These equations include source terms of mass for each VOC, based on VOC generation rates of different sources considered in the numerical model (computers, monitors, and laser printers). On the other hand, these equations are added to the basic equations describing turbulent confined non-isothermal flows (conservation of mass, momentum, energy, and turbulent quantities) in CFD modelling. The numerical model is applied in this study for a small office, taking into account a conventional mixing ventilation system (low air flow rates with different air supply temperatures). Health hazard assessments are accomplished by taking into account in the CFD model the indoor levels of the following five VOCs: benzaldehyde, ethylbenzene, o-xylene, styrene, and toluene. The CFD model proposed in this study allows achieving values of VOCs concentrations throughout the entire indoor environment. Consequently, results are presented in terms of benzaldehyde, ethylbenzene, o-xylene, styrene, and toluene concentration contours in the office, as well as mean and peak values of these VOCs in the occupied zone of the room. The results show that the estimated VOCs concentration levels due to office equipment are far below the set threshold limit values. However, the reported maximum concentrations of VOCs taken into account in the occupied zone tend to approach in some measure levels of concern with respect to odour or sensory irritation. Finally, the numerical description of VOCs sources for CFD modelling developed in this work may be extended for other indoor VOCs sources. As a result, the numerical approach proposed in this study can lead to relevant health hazard analyses, being an appropriate alternative to experimental investigations, challenging to perform in situ.