Novel approach for evaluation of air change rate in naturally ventilated occupied spaces based on metabolic CO2 time variation

Transcription

1 Downloe fom obi.u.k on: Jn 22, 2019 Novel ppoch fo evluion of i chnge e in nully venile occupie spces bse on mebolic CO2 ime viion Melikov, Asen Kiko; Mkov, Deelin G. Publishe in: Poceeings of Inoo Ai 2014 Publicion e: 2014 Link bck o DTU Obi Ciion (APA): Melikov, A. K., & Mkov, D. G. (2014). Novel ppoch fo evluion of i chnge e in nully venile occupie spces bse on mebolic CO2 ime viion. In Poceeings of Inoo Ai 2014 [Ppe HP0883] Inenionl Sociey of Inoo Ai Quliy n Clime. Genel ighs Copyigh n mol ighs fo he publicions me ccessible in he public pol e eine by he uhos n/o ohe copyigh ownes n i is coniion of ccessing publicions h uses ecognise n bie by he legl equiemens ssocie wih hese ighs. Uses my ownlo n pin one copy of ny publicion fom he public pol fo he pupose of pive suy o esech. You my no fuhe isibue he meil o use i fo ny pofi-mking civiy o commecil gin You my feely isibue he URL ienifying he publicion in he public pol If you believe h his ocumen beches copyigh plese conc us poviing eils, n we will emove ccess o he wok immeiely n invesige you clim.

2 In Poceeings of Inoo Ai 2014, July , Hong Kong, Ppe HP0883 Topic B6: Peicion & Mesuemens NOEL APPROACH FOR EALUATION OF AIR CHANGE RATE IN NATURALLY ENTILATED OCCUPIED SPACES BASED ON METABOLIC CO2 TIME ARIATION Deelin G MARKO 1,* n Asen K MELIKO 2 1 Depmen of Hyoeoynmics n Hyulic Mchines, Technicl Univesiy of Sofi, Sofi, Bulgi 2 Inenionl Cene fo Inoo Envionmen n Enegy, Depmen of Civil Engineeing, Technicl Univesiy of Denmk, Lyngby, Denmk * Coesponing emil: em@u-sofi.bg Keywos: Ai chnge e, Mesuemens, Mebolic CO2, Nul venilion, Simulion SUMMARY IAQ in mny esienil builings elies on non-ognize nul venilion. Accue evluion of i chnge e (ACR) in his siuion is ifficul ue o he nue of he phenomenon - inemien infilion-exfilion peios of mss exchnge beween he oom i n he ouoo i low e. This ppe escibes new ppoch fo ACR evluion in nully venile occupie spces. Acul mebolic CO2 ime viion eco in n inevl of ime is compe wih he compue viion of mebolic CO2 fo he sme ime inevl une efeence coniions: sleeping occupns, i-igh spce, consn inoo pessue n empeue. The popose ppoch fo ACR evluion cn be pplie o ime inevls wih ny lengh, even wih vying pmees of boh inoo n ouoo i in which mebolic CO2 geneion e is known n consn. This ppoch mkes possible evluion of vey low ACH. INTRODUCTION Inoo i quliy in mny esienil builings elies only on non-ognize nul venilion. In his cse he ACR is specifie by: ol ACR which is he volume of oom i leving he spce pe uni ime ivie by he volume of he i in he zone; ouoo ACR which is he volume of ouoo i eneing he oom, oom coniions, pe uni ime ivie by he volume of he i in he zone n bsl ouoo ACR which is cuse only by he i-pemebiliy of exenl oom bounies n is p of cul ouoo ACR. Ouoo i s well s inoo i eneing he oom fom jcen spces my conibue o he ol ACR. Evluion of bsl ouoo ACR of oom in welling wih non-ognize nul venilion is ifficul becuse of he non-sey se nue of he phenomenon. The exchnge of mss beween he inoo i n ouoo i is iven by flucuing pessue iffeence, wih smll mpliue n chnging sign, coss he i-pemeble bounies of he welling n he oom of inees, behviou cuse by sochsic fcos - win, sck effec n occupns civiies (movemen wihin he welling, opening of oos n winows, mnipuling he n impulse souces in he welling). ACR evluion in esienil spces une such coniions bse on nlysis of mebolic CO2 ime viion mkes he sk even moe ifficul becuse of he chceisics of CO2 souce, i.e. occupns wih ge in vey bo nge, iffeen helh sus, involve in vious civiies, ec.

3 In Poceeings of Inoo Ai 2014, July , Hong Kong, Ppe HP0883 The exising echniques fo ACR evluion e bse on he simplifie mss blnce fo he oom i s whole, which ssumes h ouoo i eneing he oom oom coniions, (in m 3 /s) equls flow e of i leving he oom, (in m 3 /s), n fo he CO2 in oom i which in volume unis es: X 3 10 G X X (1) whee X n X e CO2 volume fcion in oom i n ouoo i (in ppm), G is mebolic CO2 geneion in he oom (in l/s), n is i volume in he oom (in m 3 ). When G cons n X cons eq. 1 is fis oe line oiny iffeenil equion wih consn coefficiens, which hs n nlyicl soluion in he fom X ( ) eq B X X e 0 X, 0 eq B (2) whee X 0 is he CO2 volume fcion in oom i he momen 0, X, eq is he equilibium CO2 volume fcion in oom i which will be eche fe sufficienly long inevl, n B is he ol ACR (in s -1 ), which in his cse is ssume equl o ouoo ACR. Fom eq.1 fo equilibium coniions follows X eq 3 10 G X (3) B The Tce Gs Decy Technique (D sn 2012) is bse on he chnge of occupn genee CO2 n equies minimum uion of he ecoe ime inevl equl o 1/ACR. Since fo his echnique G 0 n X eq X fom equion 2 i follows h X X X X ln en ln 0 B 0 en whee X, en is oom CO2 concenion he en of he ecy inevl ( en ). The Equilibium CO2 Anlysis echnique (D sn 2012), equies minimum uion of he es ime inevl of 3/ACR which is he ime equie o ech 95% of he equilibium CO2 concenion in he oom. Ouoo ACR is clcule fom equion 3 bse on mesue X, eq, X n moel fo clculion of G, pesene in he D sn (2012). In he Two-pmees emission echnique suggese by Svov e l. (2006) equion 2 is use o obin he bes possible fi of he mesue on CO2 buil-up in he ese oom while sisfying some consins pu on he CO2 geneion em, i.e. G min G G mx. Fo his ppoch, minimum uion of he es is equl o 1.5/ACR, which is he ime equie o ech 77.7% of he equilibium CO2 concenion in he oom. All hose echniques bse on mebolic CO2 nlysis e inpplicble fo evluion of bsl ouoo ACR n even fo ol ACR of spces in wellings wih non-ognize nul (4)

4 In Poceeings of Inoo Ai 2014, July , Hong Kong, Ppe HP0883 venilion becuse: 1) low ACR he mehos equie vey long ime inevls in which ouoo pmees n pesonl pmees e consn which in mos siuions is no he cse n 2) hey ssume mss exchnge wih he ouoo i only (single zone) which is no lwys coec in cse of non-ognize nul venilion. In iion o his he Equilibium CO2 Anlysis echnique n he Two-pmees emission echnique use CO2 geneion moel which is no ccue enough s iscusse in he following. Accoing o ASTM sn D (2012), egless of oom i pessue n empeue, CO2 geneion e of subjec in (l/s) is clcule by RQ G ADM n 0.23RQ A D 0.203H W (5) whee RQ = 0.83 is he espioy quoien, H is boy heigh (in m), W is boy weigh (in kg), n M is mebolic e pe uni of sufce e (in me, 1 me = 58.2 W/m 2 ). Howeve ccoing o ISO sn (2004) equion 5 gives CO2 geneion e STPD coniions, i.e. Sn Tempeue (=0 o C) n Pessue (101.3 kp), Dy. Hence, CO2 geneion e clcule by equion 5 shoul lwys be convee o oom coniions. ISO sn (2004) efines M=40 W/m 2 fo sleeping people egless of hei sex n ge. Accoing o he Oxfo bse, Heny (2005), which povies he bes known moel fo peicion of he bsl mebolic e wih he lowes sn eo he sn esimes he bsl mebolic e coec fo mles ge n femles ge yes, uneesimes i subsnilly fo mles ge 0 10 yes n femles ge 0 3 yes, n slighly fo mles ge n femles ge 3 10 yes. The sn oveesimes he bsl mebolic e of mles ole hn 60 yes n femles ole hn 30 yes. Fom equion 3 is cle h when Equilibium CO2 nlysis echnique is use he unceiny of B linely epens on he unceiny of G. Hence, fo evluion of bsl ouoo ACR in esienil builings he CO2 geneion e mus be clcule s ccue s possible, s i is escibe by Mkov (2012). Fom equion 3 i follows h when consins e pu on he CO2 geneion em ( G G G ), like in he Twopmees emission echnique, explicily e pu especive consins on boh B n X eq. Une such consins ny non-line egession echnique cn fin only coniionlly bes fi fo B n X which my iffe significnly fom he bes one. eq A new ppoch fo ACR evluion in nully venile occupie spces h ovecomes he consins of he echniques iscusse bove is pesene in he following. BACKGROUND OF THE NOEL APPROACH In occupie spces wih non-ognize nul venilion oom i (sysem, ) inecs wih he suounings, i.e. ouoo i () n i in he jcen spce (), in vious wys: inoo i escpes o ouoo hough he winow ( m, w ) n/o hough he chimney ( m, c ), if ny, n/o o he jcen spces ( ). P of his i is eplce by some moun of ouoo i m, ( m ) n/o i fom he jcen spces ( m ). Schemic igm of he mss exchnge beween he sysem n he suounings is pesene on Figue 1. min mx

5 In Poceeings of Inoo Ai 2014, July , Hong Kong, Ppe HP0883 Doo m Winow Hee m w w c O2 m, g CO2 g 2 H O m Occupns Consuming: O 2 Geneing: CO 2, H 2 O, Me He P, T, X P T, X,, m P, T, X m c, c Chimney Figue 1. Schemic igm of mss exchnge beween he sysem n he suounings Sysem composiion (X ) is chnge coninuously since oom i is in ceseless inecion wih he occupns who consume oxygen fom i (wih e of c in g/s) n elese bck o i he, mss, cbon ioxie gs ( g CO 2 ) n we vpo ( g H 2 O ). Ouoo i pmees bsolue pessue (P ), bsolue empeue (T ) n composiion veco (X ) vies wih ime, uing he y n nnully, ue o wehe chnges, n hey peconiion viion of coesponing sysem pmees (P,T,X ) n i pmees in he jcen spces (P,T,X ). Tempeue viion in he sysem cuses especive viion of sysem mss (m ). When one o sevel occupns ene o leve he oom volume, sysem mss n sysem composiion veco e chnge sepwise. Tking ino ccoun ll hese n ssuming h i behves s homogeneous mixue of fou iel gses n pefec mixing exiss wihin he sysem volume, mss blnce fo he sysem (j=0) n fo he iniviul species - oxygen (j=1), cbon ioxie (j=2), we vpou (j=3) n ine gs (j=4), in mss unis es: O 2 m m m m S m B (6) M j whee m j, n m j, e, especively, mss flows of ouoo i n i fom he jcen spce eneing he oom, m j, is mss flow of oom i leving he oom, m j, M is mss souce of coesponing species, n m M g CO2 g H 2O c O2 fo j 0. S j is souce of mss ue o sep chnge of sysem volume, which is clcule by N p p (7) p1 whee is volume of i in he sysem, N p is numbe of occupns pesen in he oom n p is he volume of ech occupn pesen in he oom.

6 In Poceeings of Inoo Ai 2014, July , Hong Kong, Ppe HP0883 Fo he peios wih, cons, king ino ccoun equion of se fo iel gs mixues, mss blnce of he sysem, in volume unis, solve gins he ol ACR (B), es B RT P R T P RT P R T P M, T R P (8) whee R, R, n R is iel gs consn of ouoo i i in he jcen spce n he sysem, especively; is volume flow of ouoo i eneing he oom ouoo coniions, is he flow of i fom he jcen spce ( welling ) eneing he oom he coniions in he jcen spce, n M, ( m M M, ) is souce of mss in volume unis oom coniions. In equion 8 volume flow es,,, n M, e nonnegive vibles while volume flow es in he bckes, which ccouns fo he viion of sysem empeue, sysem pessue n sysem composiion, my chnge hei sign. These flows, ising fom he ccumulion em in equion 6, e efine s follows: T 1 T T, P 1 P P, R 1 R R (9) Typiclly P n R my be neglece bu fo i-igh occupie spces R is impon. Fo he peios when, cons, mss blnce of ech species in volume unis es 3 X 10 M, T P T P P, X X X B T P T P, T (10) whee M, is mss souce of species in volume unis (in l/s) oom coniions. All eils fo clculion of m j, M (in g/s) e ley pesene elsewhee (Mkov 2012), n is convesion o volume unis oom coniions is pefome by R T j M, m M P (11) THE NOEL APPROACH The ime viion of inoo i composiion une iffeen coniions cn be simule bse on mss blnce equions 8 n 10, ogehe wih he 4 species iel gs moel of he inoo n ouoo i n he expessions fo species geneion/consumpion, pesene by Mkov (2012), ssuming homogeneiy n pefec mixing of he sysem. Fou poceues fo evluion of ACR une vious coniions e elboe. Fis peio mus be selece fo nlysis of mebolic CO2 ime viion in he oom. The nlysis mus be pefome only fo he peios when occupns e sleeping, i.e. = cons n mebolic e of ech

7 In Poceeings of Inoo Ai 2014, July , Hong Kong, Ppe HP0883 occupn is close o he bsl mebolic e. Une such coniions fis eivive of CO2 signl will be posiive n coninuous. Since fis eivive of CO2 signl coul be evlue only numeiclly he smpling inevl of oom CO2 mus be no longe hn 60 s. Ai-igh nlysis. Equion 8 evels h, ue o he souce of mss in he sysem, hee is lwys n moun of i leving he oom wihou being eplce by i fom he suounings. This moun of i leving he oom consn sysem pmees (pessue, empeue n i volume) n une i-igh coniions, m 0 n m 0, following Mkov (2012) n king ino ccoun expession 11, is clcule by 4 1 Bef j. M, (12) j1 B ef is he minimum possible ol ACR fo n occupie oom given pessue n empeue. Time viion of sysem mss n mss of ll species une hese coniions is m j Bef 0 m m e m 0 (13) whee m 0 is mss of he species 0, n coesponing species. 1 m Bef m M is equilibium mss of he Tol ACR nlysis. Fo he selece peio, bse on equions 12 n 13, efeence cse is esblishe compuionlly wih he ime viion of he highes possible vlue of CO2 concenion in he oom - X 2,, ef. Tol ACR in he peio is evlue by nlysis of he viion of X 2,, ef n he mesue CO2 ime viion une he cul coniions ( X 2,, c ). A ech momen ( ) in his peio X 2, ef X2, c is mesue of he evcue volume of CO2 fom he sysem in he inevl 0 ue o is eplcemen by i fom he suounings. In n biy cse, since, cons, one p of he volume of i leving he sysem is eplce by ouoo i n he ohe p is eplce by i fom he jcen spce. Evcue volume of CO2 by eplcemen is clcule fom X 2, ef X 2, c X 2, c X 2,, X 2, c X 2,, 6 2, evc 10 0 (14) whee X 2,, c, X 2, n X 2, e he men vlues of X 2,, c, X 2, n X 2, in he inevl 0 ;, n, e men vlues of flow e oom coniions of ouoo i n i fom he jcen spce eneing he oom in he inevl 0. Minimum flow of oom i leving he sysem ( min ) is clcule fom equion 14 when ssuming i is eplce by ouoo i only n mximum flow of oom i leving he sysem ( mx ) is eche when i is eplce by i fom he jcen spce only: n mx, M, (15) min, M,

8 In Poceeings of Inoo Ai 2014, July , Hong Kong, Ppe HP0883 Fo ienificion of he possible nge of ol ACR in ech cse his poceue mus be complee fo he wo bounies of 95% confience inevl of CO2 geneion. Ouoo ACR nlysis. Fo ienificion of ouoo ACR in he selece peio oom CO2 ime viion une vious combinions of n fo in he inevl min, mx mus be simule n compe wih mesue CO2 ime viion. In he iel cse, in iion o oom CO2 ime viion, ime viion of sysem pessue n empeue, s well s pessue, empeue n CO2 concenion of boh ouoo i n inoo i in he jcen spce mus be ecoe. Usully, une sble mospheic coniions, ouoo pessue chnges slowly cusing slow chnge of sysem pessue n pessue of he jcen spce. Thus ios of ouoo pessue n pessue of he suounings o sysem pessue will equl uniy. Bse on he exmple pesene in Mkov (2012), ios of sysem iel gs consn o iel gs consn of boh ouoo i n i in he jcen spce (eq. 8) coul be ssume equl o uniy. Ienificion of n wihin he selece peio mus be pefome fo he 95% confience inevl bounies of CO2 geneion em. Thus 95% confience inevl fo n will be evlue oo. Two fee pmees empiicl moel. Fo long enough peios wih smooh CO2 buil-up in he oom he Two-pmees emission echnique (Svov e l. 2006) cn be impove wih he following moificion. Fis, he wo pmees in he moel esblishe by eq. 2 (X eq n B), mus be evlue by non-line fiing poceue. Then fom eq. 3 he 95% confience inevl bounies fo CO2 geneion em ( G EM,95, min n G EM,95, mx ) mus be evlue bse on he fo 95 % confience inevl of X eq n B. This 95% confience inevl mus be compe wih he confience inevl of G, ( G 95, min n G 95,mx ), bse on CO2 geneion moel in Mkov (2012). Ouoo ACR equls (B B ef ), when he confience inevl of G, [ G 95,min,G 95, mx ], inclues he whole confience inevl of G EM, [ G EM, 95,min, G EM,95, mx ]. When hese confience inevls ovelp les 50%, hen i coul be ssume h ouoo ACR equls (B B ef ). When G G EM n hei confience inevls oesn ovelp hen B is he ol ACH, i.e. he i leving he oom is ply eplce by ouoo i n ply by i fom he jcen spce. In his siuion Bsl ouoo ACR nlysis mus be pefome. The iscusse bove echniques e pplie n compe fo he exmple in Figue 2, which pesens eco of CO2 ime viion in n occupie oom wih non-ognize nul venilion. Duing he nigh peios 1, 2, n 3 wo occupns ( mle - ge 54, weigh 88 kg, heigh 169 cm n femle - ge 52, weigh 68 kg n heigh 159 cm) e sleeping in he oom n uing he y peio 4 only he mle subjec is sleeping in he oom. By he Equilibium CO2 nlyses ACR in peio 3 is 0.555± /h when evlue ccoing o ASTM D n 0.634± /h bse on he mebolic CO2 geneion moel by Mkov (2012). ACR peice fo peio 2 by he novel Two fee pmees empiicl moel is 0.715± /h. The novel Tol ACR nlysis echnique pplie o peio 1, which is only smll p of peio 2, peics n ACR of 0.614± /h. The iffeence in he peicions by he Equilibium CO2 nlyses escibe in he ASTM D meho n he hee novel echniques is up o 28.8%, while he iffeence in he peicions by he hee novel echniques is 14.1%. The secon p of he CO2 eco in

9 In Poceeings of Inoo Ai 2014, July , Hong Kong, Ppe HP0883 Figue 2 oesn hve n equilibium peio n heefoe he Equilibium CO2 nlyses echnique cn be pplie. The novel Two fee pmees empiicl moel pplie o he peio 4 peics ol ACR of 0.72±0.1 1/h. Tce Gs Decy Technique cn be pplie fo he enie CO2 eco in Figue 2 becuse occupns civiies uing he ecy peios e no known. Compison of he snise echniques n he novel echniques wih eil physicl mesuemens is une pogess n will be epoe in following ppe. Figue 2. ACR nlysis in n occupie oom CONCLUSIONS The pesene mhemicl moel evels he complex nue of he mss exchnge phenomenon in occupie spces wih non-ognize nul venilion s well s he esons, which mke he known poceues fo ACR nlysis no lwys pplicble o such spces. A novel ppoch fo CO2 ime viion nlysis n se of 4 logiclly connece poceues e pesene h mke possible he evluion of ol ACR, ouoo ACR s well s bsl ouoo ACR in occupie spces wih non-ognize nul venilion une wie nge of coniions in ime peios of ny lengh. This ppoch equies mesuemen of ime viion of oom CO2, pessue n empeue s well s of he empeue n CO2 of boh ouoo i n i in he jcen spce(s). REFERENCES D (2012) Sn guie fo using inoo cbon ioxie concenions o evlue inoo i quliy n venilion, ASTM Inenionl, Wes Conshohocken, PA. E (2011) Sn Tes Meho fo Deemining Ai Chnge in Single Zone by Mens of Tce Gs Diluion, ASTM Inenionl, Wes Conshohocken, PA. Heny C (2005) Bsl mebolic e suies in humns: mesuemen n evelopmen of new equions, Public Helh Nuiion (2005), 8: Cmbige Univesiy Pess. ISO (2004) Egonomics of he heml envionmen Deeminion of he mebolic e, Inenionl Ognizion fo Snizions, Genev, Swizeln. Mkov D (2012) Evluion of inoo i composiion ime viion in i-igh occupie spces uing nigh peios, In: AIP Conf. Poc. 1497, 61 (2012); oi: / Svov P, Melikov A, Sunell J e ll (2006) A new ppoch fo venilion mesuemen in homes bse on CO2 pouce by people. In: Poceeings of Ai-Coniioning n enilion Confeence 2006, Pgue, Czech Republic, pp