Abstract
Air quality is an important factor for human well-being, and it is crucial that when using mechanical ventilation system, air is properly distributed so it reaches every user of a ventilated zone. To improve ventilation systems, and in consequence the air quality, this paper focuses on studying the impact of an air terminal device (ATD) with a dynamically changing geometry on the effectiveness of a variable air volume (VAV) ventilation system. VAV system characterizes a change in the airflow magnitude through the system when the heat gains lower, which may be a risk for human health as air may not reach the furthest parts of a zone. To combat this threat, an ATD with a dynamically changing geometry was installed. As a ventilation quality indicator, the air throw was taken under consideration. Thanks to the new ATD, the steady air throw should be maintained despite the changes in flow in the ventilation system. To achieve this, the research was divided into two stages. The first stage included a series of computational fluid dynamics simulations that considered the alteration of the airflow and the air terminal device diameter. Afterwards, verifying laboratory measurements were conducted on a laboratory stand using a particle image velocimetry (PIV) system that included an air terminal device with a changing geometry. The results of the simulations and the PIV measurements showed that the changes in the geometry of the air terminal device improve the ventilation effectiveness of a VAV system, allowing the system to maintain a constant air throw despite the changing airflow magnitude through the system.
Highlights
The problem of maintaining proper indoor air quality (IAQ) is an ongoing subject and a topic of many research papers [1,2,3,4,5]
The improvement in indoor air quality (IAQ) is an ongoing subject that is fundamental to human comfort and health
The lack of a properly equipped and measured ventilation system in airtight structures may have harmful effects on occupants. This is why the aim of this research was to study the possibility of improvement of a variable air volume (VAV) ventilation system
Summary
The problem of maintaining proper indoor air quality (IAQ) is an ongoing subject and a topic of many research papers [1,2,3,4,5]. The topic is extremely important in developed countries where there is a trend to tighten the building envelope for energy savings by lessening the heat losses to the outdoor air. This trend has been fuelled by new laws. Because many current ventilation systems may not maintain adequate thermal and hygienic comfort nor adapt to the growing airtightness of buildings, ventilation systems should be improved to keep up with new construction methods that enforce the creation of increasingly tight structures, as emphasis is mainly put on energy savings and the air quality may be omitted. The work in this paper focused on improving air quality in VAV (variable air volume) systems, which are used in large buildings and which usage is increasing in small energyefficient residential buildings
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