ENERGY BALANCE FOR A THREE-WAY CATALYTIC REACTOR

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1 TEA om. Mot. Energ. Roln., 006, 6, 5 14 ENERGY BALANCE FOR A THREE-WAY CATALYTIC REACTOR Andrzej Ambrozk, Wktor Danlczyk, Stanław ruczyńk elce Unverty of Technology Waraw Unverty of Technology Summary. The paper preent the methodology of energy balance determnaton for a three-way catalytc reactor of exhaut gae. Calculaton reult and the reult of expermental mulaton nvetgaton nto the temperature change n exhaut gae flowng through the converter are alo provded. It wa demontrated that the change n exhaut gae temperature, meaured a the dfference between exhaut gae temperature a they flow out of the converter and nto t, could be ued a a dagnotc gnal. It may help to evaluate the effectvene of an exhaut gae three-way catalytc reactor. ey word: exhaut gae catalytc reactor, energy balance, dagnotc INTRODUCTION The number of automotve vehcle n ue lead to a re n fuel conumpton on a global cale and, a a reult, ncreae n the emon of exhaut gae harmful component nto the envronment. The mot mportant atmophere pollutant emtted from pton nternal combuton engne are: carbon monoxde CO, hydrocarbon HC, ntrogen oxde NO x, partculate matter PM and aldehyde RCHO, ulphur and lead compound. Preently, the mot effectve method of reducng the emon of the above-mentoned noxou ubtance the neutralaton and fltraton of exhaut gae. Smultaneou chemcal change of carbon monoxde CO, hydrocarbon HC, ntrogen oxde NO x nto ubtance that are not harmful poble due to wdely appled three-way catalyt (TWC). Long latng, extreme ervce condton of catalytc converter, the ue of fuel of dfferent, ometme low, qualte make converter get deactvated, whch deterorate a vehcle ecologcal performance. Therefore, contnuou evaluaton of a converter operatve effectvene and t techncal tate a vtal ue. One of the method of an aement of a TWC operaton effectvene the meaurement of the temperature of exhaut gae at the converter nflow and outflow. Exhaut gae temperature dfference meaured n uch a way treated a a catalytc

2 6 Andrzej Ambrozk, Wktor Danlczyk, Stanław ruczyńk converter dagnotc gnal. It caued by nternal exothermc chemcal reacton and heat tranfer. The determnaton of the above-mentoned exhaut gae temperature dfference and t applcaton to the evaluaton of a catalytc reactor effectvene poble, owng to a proper determnaton of a converter energy balance. ENERGY BALANCE FOR A THREE-WAY CATALYTIC REACTOR The equaton of energy balance for a three-way catalytc reactor neceary to determne the temperature of exhaut gae flowng out of the converter. It alo account for thermal effect of chemcal reacton proceedng nde the reactor and for heat tranfer between the flowng exhaut gae and the converter bed. The temperature of exhaut gae flowng nto the converter can be determned on the ba of the engne heat calculaton and the heat balance equaton made for the exhaut gae outlet ytem located between the exhaut gae outflow from the cylnder and ther nflow to the converter. The exhaut gae temperature can alo be meaured expermentally. Whle makng the energy balance for the exhaut gae catalytc reactor the followng aumpton are made: the reactor operate at the et condton of nternal combuton engne work, exhaut gae flow through the catalytc converter a tatonary one-dmenonal flow, exhaut gae flow through a ngle reactor channel take place at convecton heat tranfer between exhaut gae and the channel wall, four bac reacton proceed nde the reactor: the oxdaton of carbon monoxde, hydrocarbon and hydrogen and the reducton of ntrogen oxde, for whch thermal effect are determned, value of thermal effect of chemcal reacton takng place n the reactor depend on temperature and are calculated on the ba of rchoff law. The functonal dagram of a three-way catalytc reactor hown n Fg. 1. Fg. 1. The functonal dagram of a three-way exhaut gae catalytc reactor [Ambrozk A. et al.]

3 ENERGY BALANCE FOR A THREE-WAY CATALYTIC REACTOR 7 The equaton of the heat expendture balance n the reactor ha the form: & + & & & 0 (1) 1 r k = & expendture of the heat uppled wth exhaut gae flowng nto the reactor; 1 & expendture of the nternal ource of heat emtted n the reactor; r & expendture of heat tranferred by convecton between exhaut gae and the k catalytc reactor monolth; & expendture of heat convected wth exhaut gae flowng out of the con- verter. The value of the component of the reactor energy balance (1) calculated from the dependence: heat expendture of exhaut gae & flowng nto the converter calculated from the 1 formula: Τ 1 & 1 = Μ& µ c p1 (Τ Τ 1 Τ ο ) 0, W () M & klo-molar expendture of exhaut gae flowng out of cylnder and pa ng through the engne outlet (reactor), µ klo-molar pecfc heat of exhaut gae, c p1 T 1 temperature of exhaut gae at the converter nflow, T o ambent temperature. The value of the quantty M & are calculated n accordance wth the formula: n & = β r V ηv c M, µ M ρ (3) β real coeffcent of molar change, r n crankhaft rotatonal peed, V cylnder wept capacty, η degree of the cylnder fllng, v c number of engne cylnder, ρ exhaut gae denty, M µ klo-molar exhaut gae ma.

4 8 Andrzej Ambrozk, Wktor Danlczyk, Stanław ruczyńk The mean klo-molar pecfc heat of exhaut gae at contant preure calculated on the ba of the formula: T 1 + T µ c a b p = +, (4) The expendture of the heat emtted n the reactor due to the chemcal reacton takng place n t (Fg. 1): & r = M& + M& + M& + M& co pco HC phc H ph NO x pno x (5) In the dependence above, the quantte M & & & co, M HC, M H and M & NO x denote the value of klo-molar expendture of the reacton of repectve exhaut gae component, whch reacted n the converter n accordance wth Fg.1, wherea the quantte, and are the value of klo-molar thermal effect of oxdaton and pco, phc ph pno x reducton reacton n the converter. The value of M & are calculated from the dependence: M & = M& M& (6) w d M & klo-molar expendture of the -th component flowng out of the converter, w wherea M & klo-molar expendture of the -th component flowng nto the converter. d The value of the quantte of thermal effect of chemcal reacton of the exhaut gae -th component n the catalytc reactor are calculated from the formula: p = o T + α 1 + T T1 + T + β, (7) o In the formula (7), the quantte denote the value of thermal effect of the exhaut gae -th component under tandard condton; the quantte α and β are ummary pecfc heat calculated n accordance wth [Ambrozk 003], wherea T 1 and T are exhaut gae temperature at the converter nflow and outflow, repectvely. The expendture of the heat tranferred by convecton to the reactor monolth calculated n accordance wth Newton formula: T + T & 1 k = πdz Lα p Tc, W (8)

5 ENERGY BALANCE FOR A THREE-WAY CATALYTIC REACTOR 9 D z the ubttute (hydraulc) reactor dameter, L the reactor length, α the heat tranfer coeffcent, p T 1 and T exhaut gae temperature at the converter nflow and outflow, repectvely, T c the reactor wall temperature. Expendture of the heat & convected wth exhaut gae flowng out of the converter calculated from the formula: &, W (9) T = M& µ c p (T To ) Inertng dependence () (9) nto the equaton (1), a quadratc equaton obtaned, whoe oluton the value of exhaut gae temperature T at the converter outflow. The value of the dfference of exhaut gae temperature T, beng a dagnotc gnal for the catalytc converter calculated from the formula: T0 T = T T 1 (10) OBECT OF INVESTIGATIONS AND THE RESEARCH STAND The nvetgaton focued on a three-way catalytc reactor Pt-Rh/ AL O 3 -CeO, whoe monolth volume wa V m = 1. dm 3, ntalled n the engne Rover 1.4 outlet ytem. The converter, manufactured by Lndo Gobex company of Gorzów Welokopolk, Poland, ha the form of a metal monolth covered wth the upport tructure γ-al O 3 CeO wth platnum and rhodum crytallte depoted on t at the rato 5:1. Platnum and rhodum amount to.0 g/dm 3 of the monolth volume. It ha a cylndrcal hape, 100mm n dameter D and 150mm n length L. The poblty of ntallng the catalytc reactor monolth wthout an ntermedate layer or the catalytc layer of noble metal make t poble to expermentally mulate the operaton of a three-way catalytc reactor n the range from 0 to 100 of t actvty, wth the tep every 1.5. In the mulaton experment, n the converter front part, the egment of the actve monolth are ubttuted wth nactve one. The actvty of catalytc reactor defned a the rato of the volume of actve egment V a to the volume of the whole reactor V k. V V a A= (11) The effcency of the catalytc reactor beng nvetgated aeed wth the value of the converon coeffcent determned n accordance wth the formula: k

6 10 Andrzej Ambrozk, Wktor Danlczyk, Stanław ruczyńk k C C x1 x x = (1) C x1 C x1 and C x denote repectve concentraton of the -th component at the reactor nlet and outlet. Engne Rover 1.4, n the outlet ytem of whch the catalytc reactor ntalled, charactered by the followng techncal data: Cylnder dameter D c m Pton troke S m Dplacement volume V 1394 cm 3 Cylnder ytem and number R4 Compreon rato ε 10.5 Power ratng N en 76 kw Rated rotatonal velocty of the crankhaft n N 6500 r.p.m Maxmum torque M em 145 N m Rotatonal velocty of the torque n M 3000 r.p.m Whle nvetgated, the engne wa fuelled wth unleaded petrol Eurouper 95, whch comple wth the tandard PN/EN-8. Fg.. Dagram of the reearch tand: 1 magneto gnton Rover engne; three-way catalyt; 3 oxygen enor ued to control ar-fuel mxture compoton; 4 oxygen enor ued to evaluate the reactor techncal tate; 5 exhaut gae temperature enor at the reactor nflow T 1 ; Lezek Moścck, Lubln, Poland 6 exhaut gae temperature enor at the reactor outflow T ; 7 eddy-current brake HEW150; 8 exhaut gae analyer; 9 ytem for fuel conumpton meaurement; 10 et of tandard gae; 11 three-way valve

7 ENERGY BALANCE FOR A THREE-WAY CATALYTIC REACTOR 11 The reearch tand preented n Fg.. wa addtonally equpped wth: 1. The ytem for the meaurement of fuel conumpton, whch comple wth the tandard PN 88/S Computered exhaut gae analyer called Multga Analytcal Sytem Dual Purpoe manufactured by Rchard Olver Ltd, whch enable u to take meaurement of the concentraton of the followng component of exhaut gae: carbon monoxde and carbon doxde wth NDIR method; ummary amount of hydrocarbon wth FID method (converted nto propane); ummary amount of ntrogen oxde wth CLD method (converted nto ntrc oxde). Apart from the above-mentoned exhaut gae component, wth the analyer one capable of takng meaurement of oxygen contaned n exhaut gae wth the paramagnetc method. 3. A et of tandard and auxlary gae neceary for the calbraton of the ytem for meaurng the concentraton of exhaut gae poonou component. 4. Multchannel ytem for temperature meaurement, whch compre: EMT 100 ndcator by Czak Thermo company wth channel elector and temperature detector NCr NAl() of TP 371 W1 M8 1 type. 5. Computered ytem for recordng gnal from oxygen concentraton enor ung the meaurement card PCL 818 and notebook cla PC by HELIAN company. RESULTS OF INVESTIGATIONS AND CALCULATIONS The reult of expermental nvetgaton and the obtaned calculaton reult are preented n Table 1 and and n Fg. 3. Experment no. Table 1. Value of parameter and work ndexe baed on thermal calculaton for the engne and the catalytc reactor when the actvty of t operaton equal 100 G e g e q c n M e N e M λ η czr M r.p.m N m kw v kg g kg h kw h cycle

8 1 Andrzej Ambrozk, Wktor Danlczyk, Stanław ruczyńk M CO M HC M NO Table 1. contnued M H k CO HC NO pco phc pno ph pco W phc W pno W ph W W T 1 T T

9 ENERGY BALANCE FOR A THREE-WAY CATALYTIC REACTOR 13 Table. Meaurement reult obtaned n expermental nvetgaton nto three-way catalytc converter at the reactor actvty 100 [Łączyńk 004] Exper ment no. n r.p.m M e Nm t p CO O CO HC ppm NO x ppm T c T 1 T T A, Fg. 3. Comparon of expermental T b and calculated T o exhaut gae temperature dfference dependng on the mulated operaton of the catalytc reactor A T b = f(a) at n = 000 r.p.m T b = f(a) at n = 3000 r.p.m T o = f(a) at n = 000 r.p.m T o = f(a) at n = 3000 r.p.m

10 14 Andrzej Ambrozk, Wktor Danlczyk, Stanław ruczyńk CONCLUSIONS The methodology of energy balance determnaton for a three-way exhaut converter worked out by the author confrm t poble and jutfable to adopt the dfference n exhaut gae temperature at the converter nflow and outflow a a dagnotc gnal ued to evaluate the catalytc reactor effcency. The value of the abovementoned temperature dfference determned expermentally and on the ba of the energy balance propoed n the artcle do not dffer by more than 1. REFERENCES Ambrozk A. 003: Selected Iue of Thermal Procee n Pton I.C. Engne. The elce Unverty of Technology Publhng Houe, elce. Ambrozk A. et al.: Fnal report on the reearch project no. 9T1D0019. Łączyńk. 004: Dagnotc of Exhaut Gae Three-Way Catalytc Converter wth the Meaurement of the Change n ther Temperature. Doctoral the. The Waraw Unverty of Technology.

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