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Transport is responsible for around a quarter of World greenhouse gas emissions making it the second biggest greenhouse gas emitting sector after industry. Road transport alone contributes about onefifth of the EU's total emissions of carbon dioxide (CO2). While emissions from other sectors are generally falling, those from transport have continued to increase until 2008 when transport emissions started to decrease on the back of oil prices, increased efficiency of passenger cars and slower growth in mobility. The paper presents the information on EU measures to reduce fuel consumption, as well as CO2 emissions from road transport introducing limits for CO2 emission from passenger cars, vans and heavy duty trucks. These limits follow ACEA voluntary agreement on fuel consumption reduction and define the targets for CO2 emission in the year 2015 and 2020.

An appropriate type of dilution tunnel is chosen, based on the international standards, user's needs and the manufacturer’s requirements. During the design process, a number of restrictions specified in the standards for emission and Venturis were taken into account. The data required to address basic concepts were obtained from numerous emission tests performed at the IMR Institute. A short algorithm of calculation of the critical flow Venturi (CFV) is also presented. Specific attention is paid to the problems of the measurement of particulate emissions using the dilution method, which does not allow us to use the unique thermodynamic and flow parameters. A method of evaluation of particulate emissions for two extreme cases which were expected during the tests was adopted. Using the results of calculations, a full flow dilution tunnel with CFV was manufactured and tested at the IMR Institute.

Na osnovu međunarodnih standarda, potreba korisnika i zahteva proizvođača realizovan je tunel za razređenje izduvnih gasova. Pri konstruisanju tunela uzet je u obzir niz ograničenja definisanih u standardima o kontroli emisije i izboru venturija. Potrebni podaci pri definisanju osnovnog koncepta tunela dobijeni su iz brojnih ispitivanja emisije obavljenih u Institutu IMR. U radu je takođe prikazan i kraći postupak proračuna dimenzija venturija kritičnog strujanja. Posebna pažnja je posvećena merenju emisije čestica koristeći metodu razređenja izduvnog gasa, što ne dozvoljava korišćenje jednostavnih termodinamičkih i strujnih parametara. Usvojen je metod određivanja emisije čestica za dva krajnja slučaja koja se mogu pojaviti tokom ispitivanja. Koristeći rezulate proračuna konstruisan je i izrađen tunel za razblaženje punog protoka sa venturijem kritičnog strujanja koji je zatim ispitan u Institutu IMR., An appropriate type of dilution tunnel is chosen, based on the international standards, user's needs and the manufacturer's requirements. During the design process, a number of restrictions specified in the standards for emission and Venturis were taken into account. The data required to address basic concepts were obtained from numerous emission tests performed at the IMR Institute. A short algorithm of calculation of the critical flow Venturi (CFV) is also presented. Specific attention is paid to the problems of the measurement of particulate emissions using the dilution method, which does not allow us to use the unique thermodynamic and flow parameters. A method of evaluation of particulate emissions for two extreme cases which were expected during the tests was adopted. Using the results of calculations, a full flow dilution tunnel with CFV was manufactured and tested at the IMR Institute.

The paper presents the research results of DMB 1.4 l spark ignition engine equipped with prototype variable induction system. This variable geometry induction system was developed in order to investigate the possibilities of improving induction generated swirl and turbulence in combustion chamber and in this way to accelerate combustion, especially at low load engine condition. Induction channel in engine head was separated longitudinally into two sections using thin tin longitudinal wall and deflector valve at channel entrance was used to direct air flow into half channel cross section (at low engine load) or to enable full channel cross section (at full load). The results of combustion analysis show that combustion is accelerated and cycle variations are reduced at certain working conditions. In addition, specific fuel consumption is reduced, but very small, smaller than it was expected. Further geometry optimization and appropriate process managing is required.

U radu su prikazani rezultati ispitivanja prototipa turbopunjenog oto motora zapremine 1.4 l, proizvodnje DMB. Za turbomotor je razvijen elektronski sistem za upravljanje sistemom MPI ubrizgavanja goriva i paljenja. Upravljanje zaobilaznim ventilom turbine (wastegate) takođe je vršeno preko elektronskog sistema, kako bi se omogućila kontrola porasta pritiska kompresora na pojedinim režimima rada motora. U istraživačke svrhe takođe je razvijen i sistem za ubrizgavanje vode u usisni kolektor motora sa ciljem sniženja temperature ciklusa radi otklanjanja opasnosti od detonacije i sniženja temperature izduvnih gasova na ulazu u turbinu.

U radu je prikazan razvoj turbopunjenja i sistema ubrizgavanja benzina na inoviranom oto motoru zapremine 1.4 l, proizvodnje DMB. Zbog primene natpunjenja nije mogao biti korišćen standardni sistem ubrizgavanja već je razvijen novi elektronski sistem za upravljanje sistemom MPI ubrizgavanja goriva i paljenja. Takođe, regulacija pritiska nadpunjenja vršena je preko elektronskog sistema kontrole zaobilaznog ventila turbine (waste gate), kako bi se omogućila kontrola porasta pritiska kompresora na pojedinim režimima rada motora. S obzirom na moguću pojavu detonacije, razvijen je poseban sistem za detekciju ove pojave. U radu se takođe daju dobijeni rezultati optimiranja ovog turbopunjenog motora.

In this paper a simplified procedure of an internal combustion engine in-cylinder pressure record analysis has been presented The method is very easy for programming and provides quick evaluation of the gas temperature and the rate of combustion. It is based on the consideration proposed by Hohenberg and Killman, but enhances the approach by involving the rate of heat transferred to the walls that was omitted in the original approach. It enables the evaluation of the complete rate Of heat released by combustion (often designated as gross heat release rate or fuel chemical energy release rate), not only the rate of heat transferred to the gas (which is often designated as net heat release rate). The accuracy of the method has been also analyzed and it is shown that the errors caused by the simplifications in the model are very small, particularly if the crank angle step is also small A several practical applications on recorded pressure diagrams taken from both spark ignition and compression ignition engine are presented as well.

In this paper some results concerning the combined effect of the fumble flow and combustion chamber geometry layout variations on flame front shape and its propagation through homogenous mixture of isooctane and air are presented Spatial distributions of NO in different combustion chamber geometries are presented as well. The basic combustion chamber geometry layout considered consists of the flat head with two vertical valves and a cylindrical bowl subjected to variations of depth and squish area. All results presented were obtained by dint of multidimensional modeling of reactive flows in arbitrary geometry with moving objects and boundaries with modified KIVA3 and KIVA3 V source codes. Two additional computer codes were applied to generate boundary conditions for KIVA3 V calculations with moving valves. The AVL TYCON code was used for the calculation of valve lift profiles, and A VL BOOST code was used for the calculation of relevant data set in the valve regions. Different combustion chamber geometry layouts generate different levels of squish, and the combustion effects in essence depend on the interaction of that flow with tumble. It was found that for particular combustion chamber shapes with different diameter/depth aspect ratios entirely different flame front shapes and propagation velocities were encountered primarily due to variations of fluid flow patterns in the vicinity of top dead center.

U radu se daju rezultati eksperimentalnog istraživanja uticaja recirkulacije izduvnih gasova - EGR na kvalitet izduvne emisije dizel motora sa direktnim ubrizgavanjem IMR DM34/t, domaće proizvodnje. Izvršeno je sveobuhvatno veoma kompleksno ispitivanje efekta sistema EGR na sve hitnije izlazne parametre motora, a naročito na tok i promenu glavnih toksičnih komponenti izduvnih gasova dizel motora (NOx, HC, CO i dima), kao i specifične efektivne potrošnje goriva, zavisno od intenziteta recirkulacije, odnosno EGR odnosa, broja obrtaja i opterećenja motora. Primenom sistema EGR na istraživanom motoru moguće je postići veoma visok stepen redukcije azotovih oksida, uz izvesno povećanje nivoa dimnosti motora. Emisije nesagorelih ugljovodonika HC, i ugljenmonoksida CO, se takođe povećavaju i uglavnom prate tok rasta dimnosti. ., The results of the experimental research of EGR (Exhaust Gas Recirculation) effects on the direct injection diesel engine IMR DM 34/t are presented in this paper. The research of EGR system effects on the course and change of the basic toxic components in the exhaust gases of diesel engine (NOx, HC, CO and smoke) are included, as well as the specific effective fuel consumption, depending on the quantity of the recirculated gases, engine speed and engine load. By applying the EGR system on the considered engine, it is possible to achieve very high nitrogen-oxides reduction degree with a certain increase of the engine smoke quantity. Unburned HC and carbon monoxide CO emissions also increase and generally follow the smokeability increase course. .

Mathematical models of alumina/silica gel supercritical drying with carbon dioxide were studied using supercritical drying experimental data. An alumina/silica gel with zinc chloride was synthesized and dried with superciritical carbon dioxide, and its weight change was monitored as a function of drying time. The pore size distribution of the obtained aerogel was determined using the BET method and nitrogen adsorption/ desorption. The mathematical model of the supercritical drying of the wet gel was represented as unsteady and one-dimensional diffusion of solvent through the aerogel pores filled with supercitical carbon dioxide. Parallel pore model and pores in series model were developed on the basis of the measured porous structure of the aerogel. It was found that these models which use different effective diffusivity value for each pore size were in much better agreement with the experimental data than models which use an overall effective diffusivity. The local effective diffusivity coefficients were calculated using different tortuosity values for each pore size, and they were distributed according to the pore size distribution data. Model simulations of the superciritical drying with carbon dioxide confirmed that the drying temperature and gel particle diameter have a significant influence on the drying time., U ovom radu su ispitani matematički modeli sušenja alumosilikatnog gela sa natkritičnim ugljen-dioksidom na osnovu eksperimentalnih podataka natkritičnog sušenja. Sintetizovani alumosilikatni gel sa cink-hloridom je sušen sa natkritičnim ugljen dioksidom, pri čemu je praćena njegova promena mase sa vremenom. Raspodela veličina pora aerogela je određena BET metodom i adsorpcijom/desorpcijom azota. Matematički model natkritičnog sušenja je prikazan kao nestacionarna jednodimenziona difuzija rastvarača kroz pore aerogela ispunjene natkritičnim ugljen- dioksidom. Model paralelnih pora i model redno vezanih pora su razvijeni na osnovu izmerene porozne strukture dobijenog aerogela. Rezultati ukazuju da je slaganje modela paralelnih pora i modela redno vezanih pora sa različitim vrednostima efektivne difuzivnosti za pore različitih veličina i eksperimentalnih podataka, znatno bolje nego u slučaju modela koji koriste jednu vrednost efektivne difuzivnosti. Koeficiejenti efektivne difuzivnosti su dobijeni korišćenjem različitih vrednosti lokalnih izuvijanosti pora za svaku dimenziju pora, pri čemu su ovi koeficijenti efektivne difuzivnosti distribuirani na osnovu podataka o raspodeli veličina pora. Simulacijom natkritičnog sušenja je potvrđeno da temperatura sušenja i dimenzije gela imaju značajan uticaj na vreme sušenja.

Kod praktičnog optimiranja izduvne emisije dizel-motora primenom koncepta EGR (Exhaust Gas Recirculation) od velikog je interesa istražiti korelaciju između emisije azotovih oksida-NOx i ostalih toksičnih komponenti. U ovom radu će se prikazati deo dobijenih rezultata korelacije NOx-dim i NOx-HC, dok emisija ugljenmonoksida-CO nije kod dizel-motora posebno problematična pa se neće bliže analizirati njena promena, a ni korelacija sa ostalim komponentama. Međuzavisnost emisije NOx i dima dobijena tokom ovih istraživanja pokazuje da svako smanjenje koncentracije NOx u izduvnim gasovima koje se postiže primenom koncepta EGR, dovodi do većeg ili manjeg rasta dimnosti izduvnih gasova. Primena hlađenja recikliranih gasova može, zavisno od intenziteta tog hlađenja dovesti u određenoj meri do pozitivne promene te korelacije. Hlađenje EGR gasova takođe poboljšava i trade-off emisije NOx-HC, mada hlađenje dovodi do povećanja emisije nesagorelih HC. Ova činjenica u znatnoj meri komplikuje kao i u slučaju dima, optimiranje navedenog odnosa. Međutim, naknadni katalitički tretman izduvnih gasova lako redukuje HC komponente.

U radu je prikazan računski postupak za procenu greške pri merenju i izračunavanju veličina značajnih za određivanje emisije čestica dizel motora primenom gravimetrijske metode i mikro tunela za razblaženje delimičnog protoka izduvnog gasa. Analiziran je uticaj greške merenja masenog protoka usisnog vazduha primenom laminarnog protokomera i uticaj tačnosti određivanja protoka vazduha za razblaženje i ukupnog protoka razblaženog uzorka primenom masenih termalnih protokomera. Analiziran je i uticaj broja uzastopnih merenja relevantnih veličina tokom jednog mernog stupnja na tačnost određivanja masenog stepena razblaženja uzorka i ekvivalentnog masenog protoka izduvnog gasa. Primenom diferencijalne kalibracije instrumenata za merenje protoka, greška određivanja srednjeg masenog stepena razblaženja svodi se u granice od 0.2÷0.8 %, dok se greška ekvivalentnog masenog protoka izduvnog gasa, kreće u dozvoljenim granicama od 1.1÷1.9 %.

U radu se daju rezultati eksperimentalnog istraživanja uticaja recirkulacije izduvnih gasova-EGR, na kvalitet izduvne emisije usisnog traktorskog dizel-motora sa direktnim ubrizgavanjem-IMR DM34/T. Obuhvaćeno je istraživanje efekta sistema EGR na tok i promenu osnovnih toksičnih komponenti u izduvnim gasovima dizel-motora (NOx, HC, CO i dima), kao i specifične efektivne potrošnje goriva, zavisno od količine recikliranih gasova, odnosno EGR odnosa, broja obrtaja i opterećenja motora. Primenom sistema EGR na istraživanom motoru moguće je postići veoma visok stepen redukcije azotovih oksida, uz izvesno povećanje dimnosti motora. Emisije nesagorelih HC i ugljenmonoksida CO se takodje povećavaju i uglavnom prate tok rasta dimnosti. Može se konstatovati da primena sistema EGR na usisnoj varijanti traktorskog motora DM34/T daje veoma dobre rezultate u području nižih opterećenja, dok na višim i visokim opterećenjima primena navedenog sistema ukupno gledano nije celishodna, zbog bitnog povećanja emisije dima., The results of the experimental research of EGR (Exhaust Gas Recirculation) effects on the naturally aspirated tractor direct injection diesel engine IMR DM34/T are presented in this paper. The research of EGR system effects on the course and change of the basic toxic components in the exhaust gases of diesel engines (NOx, HC, CO and smoke) are included, as well as the specific effective fuel consumption, depending on the quantity of the recirculated gases, engine speed and engine load. Applying the EGR system on the engine researched it is possible to achieve very high nitrogen-oxides reduction degree with a certain increase of the engine smoke quantity. Unburned HC and carbon monoxide CO emissions also increase and generally follow the smoke ability increase course. It can be concluded that the application of the EGR system on the naturally aspirated tractor engine type DM34/T gives very good results at lower loads, while generally speaking, at higher and high loads the use of the system is questionable, and could not be justified because of the considerable smoke emission increase.

U radu je prikazan računski postupak za procenu greške određivanja masenog stepena razblaženja uzorka izduvnog gasa i njegovog uticaja na tačnost određivanja ekvivalentnog masenog protoka izduvnog gasa. Na osnovu toga analizirane su tri metode pojedinačne kalibracije masenih termalnih protokomera za gas. Analiza pokazuje da bez obzira na primenjeni princip kalibracije, direktna primena preporuka Pravilnika ECE R49 u domenu određivanja srednjeg masenog stepena razblaženja dovodi do greške u rasponu od ±0.5÷11.0 %, što metodu čini neprihvatljivom. Daljom analizom je obuhvaćena posebna tehnika diferencijalne kalibracije instrumenata za merenje ukupnog protoka razblaženog uzorka gasa i protoka vazduha za razblaženje, čijom se primenom, prema dobijenim rezultatima, greška određivanja srednjeg masenog stepena razblaženja može svesti u granice od 0.2÷0.8 %, dok se greška ekvivalentnog masenog protoka izduvnog gasa zavisno od protoka, kreće u dozvoljenim granicama od 1.1÷1.9 %., A numeric procedure for the estimation of the accuracy of diesel engine particulate emission measurement has been presented in this paper. The analysis has been provided for mass dilution ratio (DRmass) and equivalent exhaust mass flow (GEDF) regarding the particulate emission measurement based on gravimetric principle with the Partial-Flow Dilution System with heated micro-tunnel and particulate Total Sampling (PFDS-TS Type, accord. to ECE R.49 and ISO 8178). The analysis has been applied to the measurement of the air dilution (GDIL) and total diluted gas sample (GTOT) mass flows provided by means of thermal mass flow meters. Three basic flow meters calibration principles have been analyzed too. According to the results, the recommendations from ECE R49, if strictly applied, lead to the mass dilution ratio error of ±0.5÷11.0 %, which is much beyond proposed limits, making this method unacceptable. The thermal mass flow meters differential calibration procedure has been analyzed, and as a result, increased accuracy of mass dilution ratio (0.2÷0.8 %) and that of equivalent exhaust mass flow (1.1÷1.9 %) has been reported.

U radu se daju rezultati eksperimentalnog istraživanja uticaja recirkulacije izduvnih gasova-EGR, sa međuhlađenjem tih gasova pre uvođenja u usisni sistem, na kvalitet izduvne emisije dizel-motora sa direktnim ubrizgavanjem-IMR DM34/T. Prikazani su uporedni rezultati istraživanja efekta nehlađenog i hlađenog sistema EGR na tok i promenu osnovnih toksičnih komponenti u izduvnim gasovima dizel-motora (NOx, HC, CO i dima), kao i specifične efektivne potrošnje goriva, zavisno od količine recikliranih gasova, odnosno EGR odnosa, broja obrtaja i opterećenja. Primenom sistema hlađenog EGR na istraživanom motoru moguće je postići dalje povećanje stepena redukcije azotovih oksida uz izvesno sniženje rasta dimnosti motora. Takođe, hlađeni EGR dovodi do relativno malog porasta emisije nesagorelih HC i specifične efektivne potrošnje goriva u odnosu na nehlađenu varijantu sistema.

Primena turbopunjenja na dizel motorima je često korišćen način za povećanje specifične snage i smanjenje specifične potrošnje motora. Pored toga primena turbopunjenja je i efikasan način za poboljšanje efikasnosti sagorevanja, odnosno smanjenje emisije gasovitih taksičnih komponenata i dima. S obzirom na sve oštrije zakonske propise i tendenciju njihovog pooštravanja, ovaj aspekt primene turbopunjenja dobija sve veći značaj pa se većina svetskih proizvođača opredeljuje za inoviranje postojećih motora ugradnjom turbokompresora. U ovom radu prikazana su ispitivanja prototipa domaćeg motora DM33 sa ugrađenim tubokompresorom. Dosadašnja ispitivanja su dala pozitivne rezultate u pogledu smanjenja toksične izduvne emisije.