The World Health Organization (WHO), estimates that indoor air pollution is responsible for approximately 3,2 million deaths per year in 2020. Similarly, the recent COVID-19 pandemic has shown the importance of proper ventilation inside buildings as well as filtering the air breathed. Heating, ventilation and air conditioning (CVCA) systems are essential to meeting this need. These systems consist of filters and fans. The fan circulates the air through the filters. Harmful particles are then captured by the filter media.
The presence of filters upstream of the fan influences the flow and performance of the fan. In this context, this research work aims to quantify the temporal variations in the wakes of a centrifugal fan, influenced by filters positioned upstream with different efficiencies. Quantities are obtained by experimental methods using hot wire anemometers.
The results show that the addition of upstream filters influences the performance of the fan. The installation of filters increases the resistance of the system. In fact, it reduces the pressure gain by up to 50% in the case of filters installed in series. Also, the electrical power of the fan motor varies a little with the efficiency of the filters. Finally, the flow coefficient decreases by up to 17% with the addition of upstream filters.
This work also reveals velocity variations in the fan wake with increasing fan loading. The addition of an upstream filter increases the magnitude of the velocity fluctuations and evens out the velocities over the impeller height. In addition, the energy cascade shows a more complex shape which suggests that the blade loading caused by the filters increases the anisotropy of the flow. The configuration without filters is marked by low frequency instability.
Quirion, T. (Author),
Sanjosé (Supervisor) &
Di Labbio (Co-supervisor),
17 May 2023Student thesis: Master's thesis › Master in Engineering: Mechanical Engineering