The Study on Influence Factors of the Mechanical Smoke Evacuation System in Atrium Buildings

Transcription

1 Availabl onlin at Prodia Enginring 52 ( 2013 ) Th Study on Influn Fator of th Mhanial Smok Evauation Sytm in Atrium Building XU Jun-bin a, ZANG Chng a, ZAO Jun-fi b, CEN Qing-quan a, WU Jia-bao a,* a Chin Popl Armd Poli For Aadmy, Langfang , China b Jinhua Fir Dtahmnt of Zhjiang Gnral Fir Brigad, Yiwu , China Abtrat Thi papr tart from th trutur fatur and fir haratriti of an atrium building, and larifi th importan of th mhanial mok xtration ytm. Th diadvantag of China od about th mok ontrol ytm dign in an atrium ar analyzd. Th influning fator of th mok rmoval ffiiny i tudid in thi papr inluding mok vauation quantity, atrium hap offiint, mok xhaut fan tart-up tim and hat rla rat.th futur rarh dirtion i put forward aording to th onluion Th Author. Publihd by Elvir Ltd. Opn a undr CC BY-NC-ND lin Th Author. Publihd by Elvir Ltd. Sltion and pr-rviw undr rponibility of Shool of Enginring of Sun Yat-n Univrity Kyword: atrium building; mok vauation quantity; hap offiint; xhaut fan tart-up tim; fir load Nomnlatur m mok prodution rat (kg/) m mhanial xhaut rat (kg/) xh z mok layr hight (m) A atrium building ro-tional ara (m 2 ) hight of atrium building (m) mok dnity (kg/m3 ) V volum flow rat of mok vauation (m 3 /) 1. Introdution Atrium building with it killful hap trutur, bright and mutual harmony of intrnal nvironmnt, build a pial form of indoor and outdoor both iolatd and fuion, and thy giv a omfortabl fling with haring th xtrnal natural nvironmnt to intrnal taff, o thy ar widly ud. owvr, bau of it omplx intrnal funtion, vratility, havy fir load, fat mok prad pd, w an't fftivly parat th fir zon and mok zon in vrtial and horizontal dirtion. Statitial data of dad popl on atrium fir how that mok i on of th main fator that auing dath. A t of xllnt dignd mhanial mok vauation ytm an xhaut mot of th mok and 80% of hat, rdu indoor mok onntration and tmpratur gratly [1]. Contrarily, mok vauation ytm will fail in fir, auing havy aualti and lo. Thr havn t bn a omplt t of tandard for digning atrium mok vauation ytm in our ountry yt. Thr i alo no lar dfinition of th atrium in th Arhittural dign pifiation for fir prottion of tall building [2] (rfrrd to a th "high gaug"). Th tandard of diffrnt hap of th atrium i too ingl. W till u th vntilation rat mthod abandond ovra to alulat of th quantity of mok, in whih th mok xhaut quantity i dtrmind * Corrponding author Th Author. Publihd by Elvir Ltd. Opn a undr CC BY-NC-ND lin. Sltion and pr-rviw undr rponibility of Shool of Enginring of Sun Yat-n Univrity doi: /j.prong

2 Xu Jun-bin t al. / Prodia Enginring 52 ( 2013 ) aording to th volum. And thr ar no rlvant proviion on atrium gomtry, fir load, and mok xhaut fan tart-up tim and othr fator influning mok vauation fft. Thrfor, it i nary to do furthr tudy of th atrium building mhanial mok xhaut ytm, put forward raonabl dign propoal and alulation mthod, improv th xiting fir thnial rgulation, and propo a t of faibl pifiation of atrium mok vauation ytm. 2. Th mathmatial modl of atrium mhanial mok xtration 2.1. Th quation of mok layr hight Undr mhanial mok xhaut ondition, th hang of total mok ar mainly rfltd in th rlationhip btwn th amount of air ntrainmnt and th amount of mok vauation. Aording to th ma onrvation quation, th uppr layr of th mok mut b: d A ( z) m m 1 xh dt m xh V 2 NFPA 92B [3] for larg pa of mok prodution uing axiymmtri plum modl: m 0.071Q z 5 / QC 3 Subtituting Eq.(2) and Eq.(3) into Eq.(1), mhanial mok xhaut mok layr hight undr th ondition of tim an b: 1/3 5/3 dz Q z Q V dt A S A A Th mok xhaut rat to maintain a rtain mok layr hight For tady tat pro, th rat of mok hould b qual to th hight of th plum ntrainmnt rat, mak dz / dt =0: 1/3 5/3 Q z Q V S 5 Th mok tmpratur, dnity an b obtaind by th formula: T T Q / m o 353 / T Undr normal ondition, T 0 =20, p =1.02 KJ/Kg, thrfor, to kp a rtain mok layr hight rquir mhanial mok xhaut rat for: V 0.059Q z 5 / QC 7 Figur 1 how th rlationhip btwn kping a rtain rat of mok layr hight and mok vauation rat ndd undr diffrnt fir load. From th hart w an know, with th inra of th hight of mok layr, mhanial mok xhaut rat inra harply, fir load i largr, th tndny alo gt gratr. But along with th inra of th fir load, th mok xhaut rat alo inra, but th inraing trnd dra. Fir load ompard with hight, hight ha dpr influn on th xhaut rat w ndd. 3. Th dtrmination of mok vauation quantity lvl Aording to "high gaug": th volum of atrium l than m 3, mok vauation lvl hould b alulatd in aordan with th volum of 6 tim/h; atrium mor than m 3, mok vauation lvl hould b alulatd in aordan with th volum of 4 tim/h, but minimum mok vauation hould not b l than m 3 /h. Thi mthod i ordinary but it i diffiult to dign th fftiv vauation ytm whn it om to th atrium with diffrnt hap and am volum. NFPA 92B formula mthod blong to th atrium building prforman-bad dign atgory, and it u axiymmtri plum modl to alulat larg pa of mok prodution, Eq. (3). Th af mok layr hight an b alulatd from Eq. (8), thrfor NFPA 92B mok ontrol ytm dign th mok vauation lvl for: z p 6

3 510 Xu Jun-bin t al. / Prodia Enginring 52 ( 2013 ) /3 V 0.059Q ( ) Q 1/3 C 9 By th quation abov, th quantity of mok xhaut i inflund by th fir load and th longitudinal hight of atrium, and with th fir load and th longitudinal hight of atrium inra, th quantity of mok xhaut will alo inra, and th rlationhip btwn thm i approximat linar. At th am tim, if th volum of two atrium qual, but th longitudinal hight diffr, th mok xhaut quantity of th two atrium diffr abolutly, whil it alulation by th high gaug qual too, whih man th hap of th atrium ha fft on th quantity of mok xhaut. 2 In ordr to tudy th influn of hap offiint ( A / ) on th quantity of mok xhaut of an atrium, fiv atrium with diffrnt volum ar dignd, and vry atrium ha ix hap, how in tabl 1. Th fir load in th ntr ground of th atrium i 5MW, and om numrial alulation i mad to mak quantitativ analyz figur 2. It i known from th pitur that th mok xhaut quantity of th atrium with am volum dra harply whn th hap offiint inra, and th gratr th volum i, th gratr th rang of th rdution. But for th atrium with th am hap offiint, th mok xhaut quantity inra whn th volum inra. mok xhaut rat( m 3 /) From top to bottom, th fir load wr : 5MW 4MW 3MW 2MW 1MW mok vauation quantity( m 3 /h) From top to bottom, th atrium volum wr: 2500m m m m m mok layr hight( m) hap offiint Fig. 1. th mok xhaut rat hangd by mok layr Fig. 2. th mok vauation quantity hangd by hap offiint Tabl 1. th gomtri of th am volum atrium with diffrnt hap Volum (m 3 ) =0.2 =0.5 =1 Lngth (m) Width (m) ight (m) Lngth (m) Width (m) ight (m) Lngth (m) Width (m) ight (m) volum =2 =4 =8 m3 Lngth (m) Width (m) ight (m) Lngth (m) Width (m) ight (m) Lngth (m) Width (m) ight (m) In ordr to ontrat th diffrn btwn th high gaug of our ountry and NFPA 92B formula mthod, w alulat th mok xhaut quantity in th atrium of mall volum (2500 m 3 ), modrat volum (17000 m 3 ) and larg volum (30000 m 3 ) with diffrnt hap offiint undr diffrnt fir load, and onvr th quantity into vntilation rat N (N = mok xhaut quantity/volum), uh a tabl 2, tabl 3 and tabl 4, and w an : (1) For atrium with th am volum but diffrnt hap offiint, th quantity of mok xhaut alulatd by th vntilation rat mthod for high gaug i th am; but th quantity alulatd by NFPA 92B will dra with th inra of hap offiint, at th am tim, inra with th inraing of fir load. Compard with th vntilation rat mthod, thi mthod an rflt th influn of quantity of mok xhaut mad by fir load and arhittural fatur. (2) In trm of th iz of vntilation rat, for mall volum atrium, th rult alulatd by vntilation rat mthod for high gaug ar far mallr than NFPA 92B. Thi will not rah th goal of mok xhaut ffiintly. For xampl, a th fir load i 3MW, with th hanging of hap offiint(0.2~8), vntilation rat will go down from 23.6 tim to 17.3 tim,

4 Xu Jun-bin t al. / Prodia Enginring 52 ( 2013 ) but far gratr than 6 tim rgulatd by high gaug ; owvr, for mdium or larg volum atrium, th rult alulatd by vntilation rat mthod for high gaug ar largr than NFPA 92B. At thi tim, it may ntrain ambint air, whih au low ffiiny of th xhaut ytm and low onomi ffiiny. Suh a an atrium of 30000m 3, with th fir our powr for 3MW, who maximum vntilation rat hang with th hap offiint i 3.4 tim, i mallr than 4 tim rgulatd by th high gaug. (3) Th omparion abov how that th rult of vntilation rat mthod hav gratr dirpany with th atual mok prodution. Although w annot mak ur that if th rult alulatd by NFPA 92B an auratly xpr th atual mok prodution of atrium fir. And th modl till rmain to b furthr diud, but th modl i bad on larg numbr of intifi rarh, and NFPA 92B ha bn ud in th atual nginring dign in Unitd Stat. It hould b mor aptabl than vntilation rat mthod in om xtnt. Tabl 2. th vntilation rat of mall volum atrium NFPA 92B formula mthod high gaug 1MW 2MW 3MW 4MW 5MW Tabl 3. th vntilation rat of modrat volum atrium NFPA 92B formula mthod high gaug 1MW 2MW 3MW 4MW 5MW Tabl 4. th vntilation rat of larg volum atrium NFPA 92B formula mthod high gaug 1MW 2MW 3MW 4MW 5MW Th dtrmination of th bt mok fan tart-up tim In th atrium fir, th diffrnt tim th mok fan tarting, th diffrnt th trnd of th mok layr hight dvlopd, in ordr to prott th afty of popl' liv and proprty, thr nd to dtrmin th mok fan tarting tim raonably. Shngping Zhao [1] propod that whn th mok fan tarting, th orrponding mok layr hight xit uppr and lowr two ritial valu, namly t 0 hould b atifid quationt 1 t0 t2, a hown in figur 3.

5 512 Xu Jun-bin t al. / Prodia Enginring 52 ( 2013 ) Th uppr ritial mok layr hight ( z 1 ) Whn th mok layr thikn l than z1, thr may lad to th ution war phnomnon hown in figur 4. At thi tim om air i dirtly inhald by mok vnt, and mak th mhanial mok xhaut ffiiny drad. inkly [4] put forward th dimnionl numbr F an b ud to drib thi phnomnon in th natural mok xtration, givn by Eq. (10). Loughd [5] think inkly modl alo appli to drib th mhanial mok xtration, but h do not giv quantitativ valu of th ritial mok layr thikn in th tudy. mok vnt mok vnt mok layr Z 1 Smok plum flow air air Z 0 Z 2 fir Fig. 3. th uppr and lowr mok layr hight Fig. 4. ution war phnomnon uv A F ( / ) 1/ 2 5/ 2 g T T0 d 10 Aording to Morgan and Gardinr rarh, whn jut happn ution war phnomnon, mok vnt whih i loatd in mok torag pool ntr poition, F tak 1.5; and loatd in dg, F tak 1.1. Thrfor, th ritial mok layr thikn i givn by: 2/ 5 V d 1/ 2 g T / T0 F 11 So, z 1 d, and whn th mok fan tarting, th orrponding mok layr hight z 0 d Th lowr ritial mok layr hight ( z 2 ) Th purpo of mhanial mok xhaut ytm dign i to mak mok layr hight tability abov a af dign hight, namly mok fan hould b tart bfor mok layr down to th afty hight, to prott th popl' lif and proprty. Thrfor lowr ritial mok layr hight hould larg than , namly th tarting xhaut mok layr hight z Th bt mok fan tart-up tim ( t 0 ) NFPA 92B givn th atrium mok layr poition at any tim a Eq. (12) whih ro tional ara do not hang with hight: tq z 1.11 ln 4/3 12 Combind with z0 d, w know that: 1/3 t0q ln d 4/ / d 4/ Thn: t0 14 1/3 Q Q So, if you want to mak mok layr maintain abov afty dign hight, th mok fan tarting tim hould mt Eq. (14), and with th pd of mok prodution.

6 Xu Jun-bin t al. / Prodia Enginring 52 ( 2013 ) Th tudy of atrium fir hat rla rat Th fir hat rla rat i th major fator to dtrmin th dlin of atrium mok layr tmpratur and mok layr hight. NFPA 92B rommndd thr typial atrium tady-tat dign fir a follow: for limiting ombutibl, th minimum fir intnity i 2MW; othrwi, th minimum fir intnity i 5MW; and th maximum fir intnity i 25MW. National Building Cod of Canada (NBC) limit th quantity of atrium ombutibl, if th atrium hight highr than 8 mtr, th atrium ombutibl hould b l than 16g/m 3. A urvy wa arrid out by Profor Chow [8] about th atrium ground fir load dnity, h found diffrnt u atrium th fir load dnity i vry diffrnt, ranging from 0~300MJ/m 2. China od do not hav rlvant rgulation about th atrium fir load, nor hav xtniv fild rarh about atrium fir load dnity. Shanghai od [7] aborption and um up th forign tudy about atrium fir load, and giv th atrium building fir hat rla rat for dignr undr th ondition of pray or not. Thrfor, th author think that our ountry hould arry out a urvy of diffrnt hap and diffrnt u of th atrium fir load dnity, inluding th fixd fir load, th movabl fir load and tmporary fir load. Finally tablih a dign fir load dnity tabl for dignr bad on prforman and onvnin. And it i nary to trngthn th managmnt of th atrium ombutibl and thir put form, a muh a poibl to rdu th ombutibl quantity, pially om ombutibl of high hat rla rat, whih i vry important for fir afty. 6. Th futur rarh dirtion Aording to th fft of th mok xhaut volum, hap offiint, fan tart-up tim and fir load to atrium mhanial mok xhaut ytm, th author think that th furthr rarh hould b tudid from th following apt in th atrium building mok ontrol dign. (1) Atrium with th am volum but diffrnt hap hould b furthr invtigatd in th rul of mok prading in tall typ, ubi typ and flat typ. And diffrnt xhaut volum alulation mthod hould b found out. (2) Th mok xhaut fan bt tart-up tim nd quantitativ rarh, ombining fir dttion alarm thnology to raliz th linkag. (3) Carry out fir load rarh on atrium building. To atrium with diffrnt u, thr hould b a diffrnt fir intnity dign mthod. Th ful quantity and laying mod in th atrium hould b rgulatd. (4) Dign a t of dign guidlin to onform to th prnt ituation in our ountry on mhanial mok xhaut ytm of atrium building. Rgulat th impat on atrium mhanial mok xhaut ytm and improv of th norm xitd. Rfrn [1] Shngping Zhao. Th Computr Simulation and Modl Tt Rarh of th Atrium mok managmnt ytm [D]. Chongqing: Chongqing Univrity, [2] GB , Cod for Fir Prottion Dign of Tall Building, China[S]. [3] NFPA 92B, Guid for Smok Managmnt Sytm in Mall, Atria and Larg Ara, USA[S]. [4] P.L.inkly. Smok and hat vnting. SFPE andbook of Fir Prottion Enginring. Soity of Fir Prottion Engirir, Boton, [5] Ph.D P.Eng. Gary D.Loughd. Ph.D.Shu Cao. Numrial Study of th Efftivn of Atrium Smok Exhaut Sytm. ASRAE Tranation:Sympoi. [6] C.F.Zhang, R.uo, L.C.Shi, Y.Z.Li. Th Study of Smok Filling Charatriti in Larg Spa Undr DiffrntTyp of Fir [J]. Fir Sin and Thnology. 2005, 24(2): 153~154. [7] DGJ , Thnial Spifiation for Building Smok Control, China[S]. [8] WK Chow, WK Wong. On th imulation of atrium fir nvironmnt in ong Kong uing zon modl [J]. Journal of Fir Sin. 1993, 11(1): 3~51.