Experimental investigation of high airflow rate ventilation system with improved noise performance by passive and active means

Transcription

1 Experimental investigation of high airflow rate ventilation system with improved noise performance by passive and active means C. Guigou-Carter, J. Maillard and R. Wetta CSTB - Center for Building Science and Technology Work supported by Active 2009 Ottawa, Canada PAGE 1

2 Introduction Project ACTIFEN-REHAB aiming to the development of an active window for building retrofit Take advantage of the change of an old window, to install an active and smart window bringing innovative solutions with respect to ventilation, thermal, acoustic and visual comfort In order to limit the use of energy-consuming air-conditioning systems, a system including a solar protection and a ventilation apparatus is investigated Solar protection during daylight, limiting temperature increase associated to sun exposition and controlling the glare associated with sun light A high airflow rate ventilation system during night-time in order to cool down a building room such as a bedroom during summer night without opening the window Active 2009 Ottawa, Canada PAGE 2

3 ACTIFEN-REHAB Temperature control Nice, French Riviera Month of July South facing façade including 4(16)4 double pane window Comfort temperature T 27ºC enc Standard e inc omfort passive - 4_16_4 ventilation V/h 25 - mjuillet 3 /h Oc cstandard urrenc e inc passive omfort ventilation - c laire V/h m 3 -/h juillet T comfort 26% and solar protection during daytime T comfort 39% T > 27 73% Oc c urrenc e inc omfort - c laire - 4 V/h - juillet T > 27 19% T > 27 61% Standard passive ventilation 25 m 3 /h and solar protection during daytime and high airflow rate ventilation during nighttime Active 2009 Ottawa, Canada PAGE 3 T comfort 81%

4 Description High airflow rate ventilation system is to be integrated in the window frame Radial fan Duct Air outlet Ventilation system has to comply with the current French acoustic regulation: equipment noise level global index L nat 30 db(a) Radial fan selected : easy integration in the duct system and better performances in terms of airflow rate, radiated noise and power supply. Active 2009 Ottawa, Canada PAGE 4

5 Experimental Setup High airflow rate ventilation system was tested in laboratory Radial fan Air outlet Duct to be integrated in window frame Rotating microphone boom in reverberant room Active 2009 Ottawa, Canada PAGE 5

6 LnT (db ref. 20 µpa) Preliminary results Passive control Fan maximum voltage : 24 V Diagonal filter Radial Fan (noise source) Bare Duct - LnAT=55 db(a) Duct with anechoic termination - LnAT=54 db(a) Duct with diagonal filter - LnAT=48 db(a) Duct with absorbing material - LnAT=45 db(a) 40 Anechoic termination at duct end Air outlet Fan blade passage frequency Absorbing material inside duct along vertical part below diagonal filter 0 Noise level L nat above requirement Frequency (Hz) Active 2009 Ottawa, Canada PAGE 6

7 Aeraulic measurements Pressure drop measurement associated to different passive control elements Voltage supplied to fan evaluated with respect to airflow Decrease in fan voltage supply associated to decrease in noise level generated at air outlet Ventilation duct including filter and absorbing material 15 V 100 m 3 /h 16.5 V 110 m 3 /h 18 V 120 m 3 /h Active 2009 Ottawa, Canada PAGE 7

8 Active control setup Radial Fan (noise source) Reference microphone Error microphone Loudspeaker (control source) Single channel feedforward controller based on Filtered-X LMS algorithm Reference microphone position : not too close to fan due to aerodynamic turbulences inducing coherence problem, but sufficiently far away from the control plane in order to ensure causal control filter High-pass filter used on error microphone to limit low frequency impact (below 50 Hz) Air outlet Active 2009 Ottawa, Canada PAGE 8

9 Pressure Level (db) Active control result Error microphone Error microphone pressure level With control Before control More than 30 db attenuation at fan blade passage frequency More than 10 db decrease between 200 and 800 Hz Frequency (Hz) Active 2009 Ottawa, Canada PAGE 9

10 LnT (db) Active control result Sound pressure level Before control - LnAT=36 db(a) With control - LnAT=29 db(a) More than 10 db attenuation at 250 Hz third octave band More than 9 db decrease between 200 and 400 Hz Around 4 db between 500 and 630 Hz 7 db(a) improvement 0 Frequency (Hz) Requirement achieved L nat =29 db(a) Active 2009 Ottawa, Canada PAGE 10

11 Window performance Façade sound insulation Façade sound insulation for ACTIFEN-REHAB window including standard passive air inlet for permanent ventilation high airflow rate ventilation system 4(16)4 double pane window No acoustic requirements for building retrofit Façade sound insulation D nt,a,tr 30 db ACOUBAT Software : building acoustic performance evaluated from building components performance using NF EN ACTIFEN-REHAB window 1.40x1.20 m 2 Small surface area bedroom 9 m 2 Active 2009 Ottawa, Canada PAGE 11

12 Dn,e (db) R (db) Façade sound insulation Window components (16)4 double pane window - RA,tr=29 db Standard passive air inlet - Dn,e,w+Ctr=36 db High airflow rate ventilation propotype system - Dn,e,w+Ctr=45 db Frequency (Hz) Frequency (Hz) Standard passive air inlet : ACOUBAT database High airflow rate ventilation prototype : measured in laboratory Standard 4(16)4 double pane window : ACOUBAT database Active 2009 Ottawa, Canada PAGE 12

13 DnT (db) Façade sound insulation Building performance Up to 250 Hz, acoustic path thru 4(16)4 double pane window is limiting For mid-high frequencies above 500 Hz, dominant acoustic path associated to passive air inlet Façade wall 4(16)4 double pane window - RA,tr=29 db Standard passive air inlet - Dn,e,w+Ctr=36 db High airflow rate ventilation propotype system - Dn,e,w+Ctr=45 db Total 20 Frequency (Hz) Façade sound insulation D nt,a,tr =32dB Active 2009 Ottawa, Canada PAGE 13

14 Conclusions Development of high airflow rate ventilation system in order to cool down a building room such as a bedroom during summer night without opening a window Passive elements as well as active noise control successfully implemented in order to comply with the current French acoustic regulation, equipment noise level L nat 30 db(a) A standard building fitted with ACTIFEN-REHAB window found to achieve minimum value required in French acoustic regulation for façade sound insulation D nt,a,tr 30 db Control loudspeaker to fully integrate in ventilation system still under investigation Prototypes including solar protection and high airflow rate ventilation system and their regulation to be fabricated and tested in situ during summer 2010 Active 2009 Ottawa, Canada PAGE 14