Integrated Personalized Ventilation for Minimizing Cross Infection

Transcription

1 Integrated Personalized Ventilation for Minimizing Cross Infection by Peter V. Nielsen Peter V. Nielsen, Aalborg University 1

2 Personalized Ventilation Melikow et al. Peter V. Nielsen, Aalborg University 2

3 Personalized Ventilation Normally fresh air is supplied to a room with a diffuser, and this air is distributed in the room. It is usual to supply 1-5 times the volume of the room per hour, but a person only need about 0.6 m3 per hour. Therefore there is a possibility to supply a much smaller amount, when the air is supplied directly to the breathing zone By supplying the air directly to the breathing zone It is ensured that the air has not been contaminated by other persons. This will minimize e.g. cross infection and passive smoking. Personalized ventilation gives the possibility to have individual control of the thermal comfort. Also it gives the possibility to have cold air in the breathing zone and warmer surroundings. Peter V. Nielsen, Aalborg University pvn@civil.auc.dk 3

4 Effectiveness The effectiveness of personalized ventilation ε PV = c exp, o c exp, o c exp, PV c PV c PV c p c exp,pv The personal exposure index ε exp,pv = c c P exp, PV Peter V. Nielsen, Aalborg University pvn@civil.auc.dk 4

5 c R q o Exposure Level c exp,pv c exp, PV =(1/q o ) (1/ε P ) (1/ε exp,pv ) S Low exposure High air quality index Low emission High flow rate High exposure index Peter V. Nielsen, Aalborg University pvn@civil.auc.dk 5

6 Integrated Personalized Ventilation - Personalized Ventilation integrated into chairs for aircrafts, buses, trains etc. - Personalized ventilation integrated into beds for hospitals wards etc. - Personalized ventilation as source reduction devise Peter V. Nielsen, Aalborg University pvn@civil.auc.dk 6

7 Integrated Personalized Ventilation - Personalized Ventilation integrated into chairs for aircrafts, buses, trains etc. - Personalized ventilation integrated into beds for hospitals wards etc. - Personalized ventilation as source reduction devise Peter V. Nielsen, Aalborg University pvn@civil.auc.dk 7

8 Lay Outs The personalized ventilation system (LVPV)) utilizes the situations where the head or the body is in natural contact with surfaces as: chairs, pillows, clothing, head rests, blankets, walls etc. The surfaces are designed also to be a supply opening of fresh air, for example by the use of fabric as a diffuser. Peter V. Nielsen, Aalborg University pvn@civil.auc.dk 8

9 The Principle - The air is supplied to the breathing zone with a low momentum flow - The air is supplied to the boundary layer of the person, and the boundary layer transports the air further to the breathing zone. - The air is supplied to the boundary layer, and also to the surroundings of the boundary layer of a person for entrainment back into the boundary layer - The air is supplied to the breathing zone and to the boundary layer, but also supplied outside the boundary layer with a direction away from the person to create a microenvironment which is difficult to penetrate for infected particles Peter V. Nielsen, Aalborg University pvn@civil.auc.dk 9

10 Free Convection Flow Around a Person The air close to the person s surface is heated and rises due to the gravity effect. Surrounding air is entrained into the boundary layer flow, around the person. This flow is about 180 m3/h at head height. The air which the person inhales is taken from the boundary layer. LVPV flow Peter V. Nielsen, Aalborg University pvn@civil.auc.dk 10

11 High Momentum Flow or Low Velocity Supply to the Boundary Layer High momentum flow with entrainment Low velocity supply to the boundary layer Peter V. Nielsen, Aalborg University 11

12 3 Peter V. Nielsen, Aalborg University 12

13 Effectiveness 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Neck Supporter The neck support Air volume flow [l/s] NS 1 NS 2 NS 3 NS 1 NS 2 NS 3 Peter V. Nielsen, Aalborg University pvn@civil.auc.dk 13

14 Neck Supporter NS 1 NS 3 Peter V. Nielsen, Aalborg University pvn@civil.auc.dk 14

15 Peter V. Nielsen, Aalborg University pvn@civil.auc.dk 15

16 Seat Straps The seat strap Effectiveness 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Air volume flow [l/s] SS 1 SS 2 SS 3 SS 1-2 SS Peter V. Nielsen, Aalborg University pvn@civil.auc.dk 16

17 Velocity Close to the Manikin Peter V. Nielsen, Aalborg University 17

18 Flow Visualization SS Peter V. Nielsen, Aalborg University 18

19 CFD Prediction of Flow Around a Person in Seat with Seat Straps Concentration Velocity Peter V. Nielsen, Aalborg University pvn@civil.auc.dk 19

20 Integrated Personalized Ventilation - Personalized Ventilation integrated into chairs for aircrafts, buses, trains etc. - Personalized ventilation integrated into beds for hospitals wards etc. - Personalized ventilation as source reduction devise Peter V. Nielsen, Aalborg University pvn@civil.auc.dk 20

21 The Principle The personalized ventilation system (LVPV)) utilizes the situations where the head or the body is in natural contact with surfaces as: beds, pillows, mattresses, clothing, head rests, blankets, etc. Chronic obstructive lung illness and sudden infant death syndrome Peter V. Nielsen, Aalborg University 21

22 Pillow Between Head and Shoulder Peter V. Nielsen, Aalborg University 22

23 Peter V. Nielsen, Aalborg University 23 1

24 Peter V. Nielsen, Aalborg University 24 2

25 Blanket Peter V. Nielsen, Aalborg University 25

26 Peter V. Nielsen, Aalborg University 26 4

27 Draught from the Textile Diffuser 20 l/s corresponds to m/s Peter V. Nielsen, Aalborg University 27

28 Required Ventilation Rate Per Occupants Peter V. Nielsen, Aalborg University 28

29 CFD Prediction of Person with Blanket Peter V. Nielsen, Aalborg University 29

30 Integrated Personalized Ventilation - Personalized Ventilation integrated into chairs for aircrafts, buses, trains etc. - Personalized ventilation integrated into beds for hospitals wards etc. - Personalized ventilation as source reduction devise Peter V. Nielsen, Aalborg University pvn@civil.auc.dk 30

31 Integrated Personalized Ventilation as a Source Reduction Devise Li et al Peter V. Nielsen, Aalborg University pvn@civil.auc.dk 31

32 Test Room for Study of Cross Infection Hua Qian et al. Peter V. Nielsen, Aalborg University 32

33 Personal Exposure Index, Displacement Ventilation Peter V. Nielsen, Aalborg University 33 Hua Qian et al.

34 Displacement Ventilation, Stratification of Exhalation Vertical concentration gradient, measurements and predictions. Hua Qian et al. CFD predictions Peter V. Nielsen, Aalborg University 34

35 Source Patient and a LVPV Pillow Velocity distribution Concentration distribution T o = 15 o C T PV = 22 o C q o = 0.05 m 3 /s q PV = 0.02 m 3 /s Peter V. Nielsen, Aalborg University pvn@civil.auc.dk 35

36 Normalized Concentration in the Inhalation of the Target Manikin Normalized concentration = C/Cr Normalized Concentration Peter V. Nielsen, Aalborg University pvn@civil.auc.dk Different temp. of supplied air 15C supplied air temp. without PV Source with Blanket Source with pillow Target with Blanket Target with Pillow Source with pillow and relocated exhaust 0.03

37 The 2006 LVPV Team N. M. Bartholomaeussen, E. Jakubowska, H. Jiang, O. T. Jonsson, K. Krawiecka, A. Mierzejewski, S. J. Thomas, K. Trampczynska, M. Polak and M. Soennichsen, P. V. Nielsen Thank you Peter V. Nielsen, Aalborg University 37