TY  - CHAP
A1  - Alsaad, Hayder
A1  - Völker, Conrad
T1  - Measuring and visualizing the flow supplied by personalized ventilation
T2  - Proceedings Book Roomvent 2020
N2  - This study investigates the flow supplied by personalized ventilation (PV) by means of anemometer measurements and schlieren visualization. The study was conducted using a thermal manikin to simulate a seated occupant facing a PV outlet. Air velocity was measured at multiple points in the flow field; the collected velocity values were used to calculate the turbulence intensity. Results indicated that PV was supplying air with low turbulence intensity that was able to penetrate the convective boundary layer of the manikin to supply clean air for inhalation. The convective boundary layer, however, obstructed the supplied flow and reduced its velocity by a total of 0.26 m/s. The PV flow preserved its value until about 10 cm from the face where velocity started to drop. Further investigations were conducted to test a PV diffuser with a relatively large outlet diameter (18 cm). This diffuser was developed using 3d-modelling and 3d-printing. The diffuser successfully distributed the flow over the larger outlet area. However, the supplied velocity and turbulence fields were not uniform across the section.
KW  - Belüftung
KW  - Luftqualität
KW  - Personalized ventilation
KW  - Schlieren imaging
KW  - Air quality
KW  - Thermal manikin
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20220622-46573
CY  - Turin, Italy
ER  - 
TY  - JOUR
A1  - Alsaad, Hayder
A1  - Völker, Conrad
T1  - Could the ductless personalized ventilation be an alternative to the regular ducted personalized ventilation?
JF  - Indoor Air
N2  - This study investigates the performance of two systems: personalized ventilation (PV) and ductless personalized ventilation (DPV). Even though the literature indicates a compelling performance of PV, it is not often used in practice due to its impracticality. Therefore, the present study assesses the possibility of replacing the inflexible PV with DPV in office rooms equipped with displacement ventilation (DV) in the summer season. Numerical simulations were utilized to evaluate the inhaled concentration of pollutants when PV and DPV are used. The systems were compared in a simulated office with two occupants: a susceptible occupant and a source occupant. Three types of pollution were simulated: exhaled infectious air, dermally emitted contamination, and room contamination from a passive source. Results indicated that PV improved the inhaled air quality regardless of the location of the pollution source; a higher PV supply flow rate positively impacted the inhaled air quality. Contrarily, the performance of DPV was highly sensitive to the source location and the personalized flow rate. A higher DPV flow rate tends to decrease the inhaled air quality due to increased mixing of pollutants in the room. Moreover, both systems achieved better results when the personalized system of the source occupant was switched off.
KW  - Strömungsmechanik
KW  - Kontamination
KW  - Belüftung
KW  - Luftqualität
KW  - computational fluid dynamics
KW  - cross-contamination
KW  - ductless personalized ventilation
KW  - indoor air quality
KW  - tracer gas
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20200805-42072
UR  - https://onlinelibrary.wiley.com/doi/full/10.1111/ina.12720
VL  - 2020
PB  - John Wiley & Sons Ltd
ER  -