chibosv2.wordpress.comChng I:

KHI NIM CHUNG

1. KHNG KH V C TNH CA N. Khng kh l mt mi trng m con ngi sut cuc i sng, lm vic v ngh ngi trong . Sc kho, tui th v cm gic nhit ca con ngi ph thuc vo thnh phn hn hp ca khng kh, trong sch v c tnh l ho ca n. Ta c th khng nh rng mi trng khng kh v cng quan trng v khng th thiu c i vi s sng ca con ngi v cc h sinh thi khc. Nhim v ca k thut thng gi l phi to ra mi trng khng kh tht trong sch c y cc thng s: nhit , m, tc chuyn ng ca khng kh ph hp vi yu cu mong mun ca con ngi v p ng c yu cu cng ngh ca cc nh my.

1.1. Thnh phn ho hc ca khng kh.Khng kh l hn hp ca nhiu cht kh m ch yu l kh nit, xy v mt t hi nc. Ngoi ra trong khng kh cn cha mt lng nh cc cht kh khc nh cacbonnic, cc cht kh tr: Acgon, Non, Hli, zon bi, hi nc v cc vi trng. Khng kh cha hi nc gi l khng kh m. Ngc li l khng kh kh. Thnh phn ho hc ca khng kh kh tnh theo phn trm (%) th tch v trng lng cho bng1.1 Bng 1-1 thnh phn ho hc ca khng khLoi kh Ni-t - xy Argn Cc bnic Nn, Hli Krptn, xenon Hyr, zn K hiu N2 O2 Ar CO2 Ne, He Kr, Xe H2, O3 T l % theo th tch Th tch 78.08 20.95 0.93 0.03 Khng ng k Khng ng k Khng ng k Trng lng 75.6 23.1 1.286 0.046 Khng ng k Khng ng k Khng ang k

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chibosv2.wordpress.comThnh phn hi nc trong khng kh m thay i theo thi tit, theo vng a l v theo thi gian trong ngy, trong nm. Trn y l thnh phn t nhin ca khng kh sch. Trong thc t do hot ng sinh hot, hot ng cng nghip v hot dng giao thng vn ti ca con ngi cng nh do t nhin m trong khng kh cn c nhiu cht kh c: SO2, NO2, NH3, H2S, CH4 v hi lm nh hng ln n sc kho con ngi v sinh vt ni chung.

1.2. Cc thng s l hc ca khng kh m.Chng ta coi khng kh m l hn hp ca khng kh kh v hi nc. Trong phm vi sai s cho php ca k thut ta c th xem khng kh m l hn hp ca 2 cht kh l tng, do tun theo nh lut Bon Mariot v Gay Lutxac vit phng trnh trng thi ca chng nh sau: i vi 1 kg khng kh: PV = RT i vi G kg khng kh: PV = GRT Tron : (1-1) (1-2)

+ P: p sut ca cht kh [ mmHg; KG/m2] + V: Th tch n v ca cht kh. [m3 + T: Nhit tuyt i ca cht kh [0K]. T = t + 273

Nu ta ly mt khi khng kh m c th tch V(m3); di p sut kh quyn Pkq v cng nhit tuyt i T[0K] v trng lng G tch ra 2 thnh phn ring bit l khng kh kh v hi nc, theo s biu din sau y:V,T V,T Gk Pk V,T Ghn Phn

GPa

=

+

Theo nguyn l bo ton trng lng G = Gk + Ghn (1-3) Theo inh lut anton: Pkq = Pk + Phn (1-4) Phng trnh trng thi vit cho tng khi kh ring bit nh sau: - i vi thnh phn khng kh kh:2

chibosv2.wordpress.comPk.V = Gk.Rk.T (1-5). - i vi phn hi nc: Phn.V = Ghn.Rhn.T (1-6). Trong : + Pkq [mmHg]: p sut kh quyn. + Pk, Phn [mmHg]: p sut ring phn ca khng kh kh v ca hi nc. + G, Gk, Ghn [kg]: Trng lng khng kh m, trng lng khng kh kh v trng lng phn hi nc ca khng kh. + Rk = 2.153mmHg.m 3 : Hng s ca khng kh kh. kg 0 K mmHg.m 3 : Hng s kh ca hi nc. kg 0 K

+ Rhn = 3.461

Da vo cc phng trnh t (1-1) (1-6) ta xc nh c cc thng s vt l ca khng kh m. 1.2.1. m ca khng kh: c 2 loi m khc nhau - l m tuyt i v m tng i. a) m tuyt i: k hiu D [kg/m3] + inh ngha: m tuyt i ca khng kh l i lng biu th lng hi nc cha trong 1 m3 khng kh m. + Cng thc tnh: D =P G hn = hn (1-7) V R hn .T

Thay Rhn = 3.416

mmHg.m 3 vo (1-7) kg 0 K

ta c D = 0,289

Phn (1-7 a) T

p sut v nhit nht nh, nu khng kh bo ho hi nc th m tuyt i ca n n s c gi tr ln nht v gi l m tuyt i bo ho (Dbh): Dbh =Pbh . (1-7 b) R hn

Khi t trng thi bo ho khng kh khng cn kh nng nhn thm c hi nc na. Nu cung cp thm hi nc vo khng kh th ngay lc lng hi

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chibosv2.wordpress.comnc tha s ng li thnh nc, hin tng ny ta gi l hin tng ng sng. b) m tng i: [%]. + inh ngha: m tng i ca khng kh l i lng biu th bng t s gia m tuyt i D v m tuyt i bo ho (Dbh) cng nhit v p sut: + Cng thc: =P D 100% = hn .100% (1-8) P bh D bh Phn .100% => Pbh = Phn (1-9) P bh

= Trong :

Phn : p sut hi nc bo ho.

m tng i ca khng kh biu th mc no hi nc ca khng kh. 1.2.2 Dung m: d [g/kg khng kh kh; kg/kg khng kh kh]. + nh ngha: Dung m l i lng biu th lng hi nc tnh bng gam (hay kilgam) cha trong mt khi khng kh m c trng lng phn kh l 1kg. + Cng thc: d =G hn 103 (1-10 a) Gk

Thay Gbn v Gk t phng trnh (1-5) v (1-6) ta c: D=R k Phn mmHg.m 3 103 m Rk = 2,153 ; Rk = 3.461 R hn Pk kg 0 KPhn [g/kg khng kh kh] Pk

Vy d = 622

Thay Phn = Pbh vo ta c: D = 622Pbh [g/kg khng kh kh] (1-10) Pkg Pbh

1.2.3 Trng lng n v ca khng kh m: [kg/m3]

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chibosv2.wordpress.com+ nh ngha: Trng lng n v ca khng kh m l trng lng ca 1 m3 khng kh m: + Cng thc: =G G k + Ghn = V V

Rt Gk v Ghn t (1-5) v (1-6) thay vo ta c:Pk P + hn Phn R k R hn mmHg.m 3 1 Pk + = ( ) m Rhn = 3.461 T T R k R hn kg.0 K1 1 (0,465 Pk + 0,289 Phn) = [0,465 (Pk + Phn) 0,176Phn] T T 1 (0,465 Pkq 0,176 Phn) T 1 (0,465 Pkq 0,176Pbh) (1-11). T

= => = = = Nhn xt:

Trng lng khng kh m () hon ton ph thuc vo p sut kh

quyn, nhit ca khng kh, m tng i ca khng kh v p sut hi nc c trong khng kh. Nu khng kh hon ton kh th Phn = 0 v do : k =0,465 Pkq T

=> = k 0,176

P Phn = k 0,176 bh (1-12). T T

ta c th xc nh c trng lng n v ca khng kh nhit t theo cng thc sau: t =01+ t 273

[kg/m3]

nu Pkq = 760 mmHg th 0 = 1,293 Kg/m3 nn. t =1,293 [kg/m3] t 1+ 273

1.2.4. Nhit hm (nhit dung hay entanpi) ca khng kh m.K hiu I5

chibosv2.wordpress.com+ nh ngh; Nhit hm ca khng kh m l nhit cha trong mt khi khng kh m c trng lng phn kh l 1 kg. K hiu I, n v Kcal/kg khng kh kh. + Cng thc: I = Ik + Ihn Trong :d 1000

I: Nhit hm ca khng kh m, Kcal/kg khng kh kh. Ik: Nhit hm ca khng kh kh. Ik = Ckht Ckh: T nhit ca khng kh kh.Ckh = 0,24 Ihn: Nhit hm ca hi nc: Ihn = r + Chn.t r: 597,3 (Kcal/Kg) nhit ho hi ca nc. Chn = 0,44(Kcal/Kg t nhit ca hi nc.Kcal kg 0 C

Thau vo:

I = 0,24t + (597,3 + 0,44t)

d 1000

(1-14) (Kcal/Kg khng kh kh)

1.2.5 Nhit khng kh: Nhit khng kh l yu t nh hng rt ln n cm gic nhit ca ngi trong nh, nhit khng kh ph thuc vo bc x mt tri, n lun thay i tng gi trong ngy, tng ma trong nm. ng cong biu din s thay i nhit khng kh tng ng vi ng cong biu din cng bc x mt tri nhng do qun tnh nhit nn n chm hn 1 s gi. Thng thng trong mt ngy m, nhit cao nht vo lc 13h. Trong nm nhit cao nht vo thng 7 v thp nht vo thng ging. Trong tnh ton thng gi phi bit c a im xy dng cc a phng Tra bng ph lc mt s gio trnh. 2: BIU I.D CA KHNG KH M:

2.1 Gii thiu -Cu to biu I.d.Trong thng gi mun xc nh mt trng thi bt k ca khng kh ta cn t 3 n 5 thng s l: t, , I, d, v Phn ch khng th xc nh trng thi ca khng6

chibosv2.wordpress.comkh mi ch bit 2 thng s: Cho nn trong tnh ton s gp rt nhiu kh khn v phc tp. tin li v nhanh chng, trong k thut ngi ta lp biu th hin mi quan h gia cc thng s ca trng thi khng kh m. Vic lp biu cc nc c khc nhau. Cc nc t bn thng dng biu I-t ca Mollier (c). Cc nc x hi ch ngha (Lin X c) v a s cc nc dng biu I-d ca Gio s RamZin(Nga) thit lp nm 1918. Nh c biu ny, nu bit trc 2 trong cc thng s trn ta c th tm c cc thng s cn li. lp biu I-d ngi ta s dng 2 phng trnh (1-10) v (1-14) d = 622 P' ' hn (1-10) [g/kg khng kh kh] Pkq P' ' bhd (1-14) [Kcal/kg khng kh kh] 1000

Ia = 0,24t + (597,3 + 0,44t) Cu to ca biu

Hai trc ca biu hp vi nhau 1 gc 1350. Trn th biu din cc thng s: t, , I, d, Phn. ng = 100% chia biu thnh 2 vng: Vng pha trn c trng cho khng kh cha bo ho hi nc, n cn c kh nng nhn thm hi nc. Vng pha di l vng khng n nh. Khng kh nm trong vng ny c xu hng tr v trng thi bo ho gii hn = 100%, hi nc tha trong khng kh s ngng li thnh nc. Trc tung, trn ghi cc gi tr ca nhit hm I (Kcal/kg) v trc honh, trn ghi cc gi tr ca dung m d (g/kg khng kh kh) Cc ng nhit hm I = Const i xin song song vi trc honh d. Cn cc ng dung m d = const c hng thng ng song song vi trc tung I. Ngoi cc ng I v d, trn biu I-d cn c cc ng ng nhit t = const v m tng i = const. Cc ng t = const l nhng ng thng gn song song nhau hng chch ln trn, ti pha gc ca mi ng ta ghi tr s nhit ca n. Cc ng = const l ng cong biu th mc no hi nc ca khng kh c xp ln lt t trn xung di theo tr s tng dn (Hnh 1-1)

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chibosv2.wordpress.com

Hnh 1-1 cho kch thc biu gn nh, thng thng trn biu khng th hin trc d thc (tc trc d xin gc) m ch c trc honh ph tr hp vi trc tung thng gc 900 nh cc h trc vung gc khc v trn trc ph tr y ngi ta chiu t l xch cc tr s dung m d t trc d xin gc xung (hnh1-2)

HNH 1-2

Khi p sut kh quyn tng cao th ng bo ho = 100% ca biu I-d dch chuyn ln pha trn v ngc li. p sut kh quyn thay i trong phm vi 20 mmHg th s dch chuyn y khng ng k nn vic s dng biu I-d lp vn m bo chnh xc. Thng thng ngi ta lp biu I-d vi p sut kh quyn Pkq = 760 mmHg v Pkq = 745 mmHg. pha di biu I-d ngi ta v ng biu din p sut ring ca hi nc Phn trong khng kh m.8

chibosv2.wordpress.comMt im bt k no trn I-d cng c trng cho trng thi nht nh ca khng kh. Tht vy, nu A l im c trng cho mt trng thi khng kh no th ng vi trng thi khng kh ta s c nhit tA v p sut ring ca hi nc Phn(A) V d: cho trng thi khng kh c tA= 320C, m A = 60%. Da vo biu I.d tm cc thng s cn li: IA, dA, Phn(A) khi bit Pkq= 760 mmHg. Gii: Dng biu I.d lp cho Pkq= 760mmHg, ta tm c to im A (tc l giao ng tA=320C v A = 60% ). Ti im A ta c c tr s dA = 18 g/kg; IA= 18,7 Kcal/kg v Phn(A)=21,4 mmHg. Cch xc nh th hin trn ( hnh 1-3)

HNH 1.3

Hnh 1.3 9

chibosv2.wordpress.com2.2. Cc im c bit trn I.d.2.2.1 im khng kh bo ho hi nc. im c m tng i = 100% gi l im khng kh bo ha hi nc. Ti y khng kh khng nhn thm hi nc na v no. Nu tip tc cung cp hi nc s xut hin hin tng ng sng. 2.2.2 Nhit t: t (0C)

Hnh 1.4+ nh ngha: nhit t l nhit cn thit c c trng thi khng kh bo ho hi nc. Trong iu kin nhit dung khng thay i. + V d: Cho trng thi khng kh A (tA, A). Yu cu tm nhit t tng ng (A) ca trng thi A. Hnh 1-4 +Gii: T tA v A ta tm c v tr A trn biu . Qua A k ng IA= const. Ct ng = 100% ti im M. Tm nhit qua im M. l nhit t ca trng thi (A). 2.2.3. Nhit im sng. + nh ngha: Nhit im sng l nhit cn thit c c trng thi khng kh bo ho trong iu kin dung m khng thay i. + V d: Cho trng thi khng kh A (tA, A). Yu cu tm nhit im sng ca trng thi A (ts(A)). Hnh 1-510

chibosv2.wordpress.com+Gii: T tA v A ta tm c v tr A trn biu . Qua A k ng dA= const. Ct ng = 100% ti im S. Tm nhit qua im S. l nhit im sng ca trng thi (A).

Hnh 1.52.2.4. Cc qu trnh thay i trng thi ca khng kh. a) Qu trnh sy nng v lm lnh: Qu trnh sy nng v lm lnh trng thi khng kh m khng c s thay i ca dung m (d=const) c thc hin trn biu I.d Hnh 1-6

Hnh 1.611

chibosv2.wordpress.comNu khng kh c trng thi ban u biu din bng im 1(t1, 1) c sy nng trong thit b trao i nhit th qu trnh c biu din bng ng thng ng hng t di ln i qua im 1. Nu lm lnh th chiu ngc li (Hng xung di). Nu tip tc lm lnh khng kh n im 3. im 3 l nhit ng sng ca trng thi K (1). b) Qu trnh ho trn: Trong thng gi tit kim nhit v ma ng ngi ta ho trn hai trng thi khng kh c thng s khc nhau to thnh trng thi th 3 c thng s ph hp. Gi s khi khng kh A c khi lng GA(kg), nhit hm IA v dung m dA ho trn vi khi khng kh B c khi lng l GB(kg), nhit hm IB, dung m dB. Sau khi ho trn khi khng kh ho trn c trng thi C vi khi lng GC = GA+ GB. Khi cho A v B ho trn vi nhau, chng s trao i nhit v trao i m cho nhau. Ta vit c phng trnh cn bng nhit GAIA + GBIB = (GA+ GB)IC GA(IA IC) = GB(IC - IB)GA GB

=

IC - IB =n IA - IC

(1-15)

Phng trnh cn bng m: GAdA + GBdB = (GA + GB) IC GA( d A - d C ) = GB( d c - d B )GA GB

=

dC - dB =n dA - dC

(1-16)

T (1-15) v (1-16) ta c:IC - IB d -d G = C B = A = n (1-17) IA - IC dA - dC GB

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chibosv2.wordpress.comPhng trnh (1-17) l phng trnh chnh tc ca ng thng i qua 3 im: A(IA, dA); B (IB, dB) v C (IC, dC) hay ni cch khc im C c trng thi (IC,dC ) nm trn ng thng ni AB v chia on AB theo t s n =GA . GB

By ta tm c dim ho trn C bng cch. t vct trng lng GA v GB song song v ngc chiu nhau. Ti A t vc t GB ,t i B t vc t GA. Ni 2 u mt ca vct ct AB ti C. im C l im ho trn, ti khng kh c thng s C(Ic,dc,) v khi lng Gc.

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chibosv2.wordpress.com3. TC DNG CA MI TRNG KHNG KH N CON NGI V CC QU TRNH SN XUT. 3.1 Tc dng ca mi trng khng kh n con ngi.3.1.1 Phng trnh cn bng nhit gia c th vi mi trng. Gia c th vi mi trng lun trao i nhit cho nhau. Phng trnh cn bng nhit c vit nh sau: M Qbx QL QMT -Qmh +QLV Q = 0 (1-18) a. M[ Kcal/h]: Lng nhit do cc qu trnh sinh l trong c th sinh ra. Lng nhit M ph thuc vo: - c im sinh l ca c th, la tui. - Trng thi v mc lao ng. - Tnh trng sc kho. - Mc n mc. Thng lng nhit M c tra bng. Bng 1-2: Lng nhit do qu trnh sinh l trong c th sinh ra Dng cng vic M (Kcal/h) 1-Ngi trng thi yn - Nm - Ngi - ng - ng nghim 2-Lao ng chn tay -May my, sp ch (in) 100-120 70 75-80 85 90-100 -nh my ch,s dng my cng c,cc cng vic tng ng. - Cng tc c (luyn kim) - o t rn 3-Lao ng tr c. - c sch - Ging bi 100 170-270 120-170 150-250 250-420 Dng cng vic M[Kcal/ h]

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chibosv2.wordpress.comb. Lng nhit c th trao i vi mi trng bng bc x: Qbx = 2,16(35-tbx) [Kcal/h] (1-19) -2,16: h s - 35 = tda: nhit b mt da. - tbx [0C]: nhit bc x trong phng. tbx =

Fii Fi

(1-20)

Fi v i: Din tch v nhit b mt ca kt cu th I trong phng. c. Lng nhit c th trao i bng i lu. QL = 8,89 v (35-tk) [Kcal/h] (1-21)

v: vn tc gi trong phng (m/s) tk: Nhit khng kh trong phng (0C) 35 = tda: nhit b mt da.

d. Lng nhit do bc x mt tri chiu vo: QMT = (1-a) I FCT [Kcal/h] (1-22) - a: H s phn bc x ca b mt da hay qun o ph thuc vo mu sc. V d: + Da mu trng: a = 0,45 + Da mu vng: a = 0,4 + Da mu en: a= 0,160,22 - I [Kcal/m2h]: Cng bc o mu trng: a = 0,75. Bc x ca mt tri chiu vo ngi tra bng theo ti liu kh hu ca a phng. - FCT (m2): Din tch b mt c th chu bc x mt triv c th ly nh sau: + Khi ng: F = 0,6. m2 + Khi ngi: F = 0,25 m2

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chibosv2.wordpress.come. Lng nhit m c th trao i vi mt tri do bc hi m hi. Qmh = 29,1.v0,8(42-eT) [Kcal/h] (1-23) - v(m/s): vn tc gi trong phng. - eT(mmHg): p sut ring ca hi nc trong khng kh. - 42: p lc ring ca hi nc bo ho trn b mt da. f: Lng nhit tn hao cho lao ng c hc ca con ngi: Lng nhit ny chim t 2035% lng nhit do sinh l sinh ra ca con ngi v c tnh: Ql = 0,2 (M-My) (1-24)

- M[Kcal/h]: lng nhit do qu trnh sinh l sinh ra khi c th lao ng. - My[Kcal/h]: lng nhit do qu trnh sinh l sinh ra khi con ngi khng lao ng. h. Q[Kcal/h] = M - [ Qlx QL-Qmh+QMT+Qlv] (1-25)

Q: Lng nhit cong li trong c th_N quyt nh cm gic nhit ca ngi trong phng. - Q>0: c th con ngi tha nhit, nn cm gic nng bc kh chu. - Q10 m v ri trong khng kh c gia tc. Nng bi trong t nhin ph thuc vo a im: nng thn, rng ni t bi hn thnh ph v khu th Tt c cc loi bi u gy hi i vi con ngi di cc dng sau: - Bin dng dn c phi do bi silic, bi aming, bui XM - Gy c do th phi bi ch (Bb), bi Asen (As) - Gy vng da do th bi km. Mun gim tt nht lng bi trong khng kh ta phi tin hnh lc bi trc khi a khi a khng kh vo phng, ht v lm sch bi kh thi trc khi thi vo mi trng.

4.2 Kh c hi: c nhiu loi.4.2.1 Mi hi thi: Thng c sinh ra t nh bp, khu v sinh trong cc phng th nghim, trong cc phn xng sn xut v qu trnh phn hu cc cht hu c trong mi trng. nc ta, iu kin gi v sinh khng tt, thi tit ma nng tht thng to iu kin cho s pht trin mi hi thi, nm mc 4.2.2 Kh c hi trong cng nghip: Cc nh my sn xut cng nghip u sinh ra cc loi khi c hi nh CO, CO2, SO2, Nox - Kh CO: sinh ra do qu trnh chy khng hon ton khi t nhin liu l than, l loi kh c hi i vi con ngi. - Kh SO2: l kh khng mu, c mi kh chu. nh hng n h h hp v lm tn thng phi. Kh SO2 c hnh thnh do t nhin liu c cha hp cht lu hunh.21

chibosv2.wordpress.com- Hi Clo (Cl2): c mi kh chu, tc dng n b my h hp, nng cao lm ri lon nhp tim v gy t vong. - Hi Clorua hyr (HCl): Gy run git, tn thng ph qun c kh nng n mn kim loi. Ngoi ra, trong cc dy chuyn sn sut, cn sinh ra cc cht kh c hi khc nhau. Tu theo thi gian tip xc v nng ca chng m c th nh hng trc tip hoc gin tip n sc kho con ngi v cc h sinh thi khc.

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