Biofuels with Content of Bioethanol for Diesel Engines

Transcription

1 Biofuels with Content of Bioethanol for Diesel Engines J. Kára Research Institute of Agricultural Engineering, Drnovská 57, P.O. Bo 54, Praha 6 Ruzynì, Czech Republic Abstract In the paper is described result of measuring of smokeness and emissions of untreated diesel engine Zetor 771 operating with alternative fuels (rape oil methyl-ester, addited ethanol fuel) and diesel oil.from comparison of emissions and smokeness (according to EHK 49 and EHK 24 directives) results, that ethanol fuel has in this field absolutely the best properties. Very favourable are the significantly lower values of measured emissions NO compared not only with the diesel oil, but also with the rape oil methyl-ester. Specific emissions at the ethanol fuel are roughly half in comparison with other fuels. The CH emissions are at this newly formulated fuel higher what can be eplained by the fact, that the tested engine has not been equipped by the catalyst. The most significant positive effect was reached in comparison with the diesel oil in radical reduction of the spirit fuel smokeness. The measurements are confronted with foreign results where very similar values were found out. French and Sweden operation eperiences with that fuel displayed, that long-time operation needs the engines adaptation and usage of catalysts to reach the optimal results. Negative point of this ecological fuel is worse economy of its utilization. Key words: internal combustion engine emissions, diesel engines, bioethanol, rape oil methylesters Introduction Fermented ethanol (bioethanol) has about 5% worse heat value compared with diesel oil and higher specific consumption in engines because of it. From this poit of view, the rape oil methyl esters (biofuel) are better as alternative fuel for diesel engines. Nevertheless, there is known application of bioethanol in diesel motors. Its emissions composition ( low smokiness particularly) is very favourable for bioethanol application. Usually resulting emissions could be decreased by engine construction changes, use of catalysts and, last but not least, suitable composition of fuel formulation. Realization Abroad In France, bioethanol is used as a basic fuel component in pilot operation of diesel bus engines in public transport in Tours. The motor has adjusted construction and catalyst [L 1], [Gaouyer, 1996]. The fuel ( 9% of bioethanol approimatly, about 4% of AVOCET 1 additive as ignition accelerator, the rest - alkohols as denaturing additives) has about 25% lower price then diesel oil (regarding bioethanol ta eemption), but about 84% higher consumption related to the same energy content of specific fuel unit (1 l of diesel fuel corresponds to 1.84 l of biofuel). Similar pilot tests in Sweden [L 1]show somparable results. The engine (SAAB-SCANIA DSI 11 E) has adjusted construction and catalyst. Utilization of fuel in public transport is ecological friendly from the point of view of emission composition and smokiness, but the operation is more epensive comparing with diesel oil and biofuel (of methylesters of rape oil). The metods VÚZT proposed comparable program of tests of alternative renewable fuels with diesel oil 64

2 for diesel engines [Kára, 1999]. Measurement was carried out in cooperation with VÚZT SZ No.22 (in TU Liberec). The aim of measurement was to compare operation characteristics and emission of diesel motor operating on diesel oil and alternative fuels - methyl ester of rape oil and bioethanol with AVOCET additive. The ethanol has higher ignition temperatures then which will be achieved by air compression in diesel motor, because of it has to be added by the accelerator of ignition (for e. of AVOCET type). The maine aim of eperiments was to compare gaseous emissions (CO, CH a NO ) and smokiness of engine operating on partikular mentioned fuels. Used technics, materials and equipment Engine ZETOR 771 No.128 engine was prepared to tests. It was installed in ZETOR 7711 No.9861 manufactured in ZETOR 771 engine is four-stroke, in-line, liquid-cooled, vertical four-cylinder motor with direct fuel injection and distribution system OHV. cylider bore 12 mm, stroke of pistons 12 mm, cylinder volume 922 cm, compression ratio 17:1, rated speed 22 min -1, rated power 52 kw, fuel injection pump PP4M9K1e-17, injection jets DOP 16S44-6. Fuels At tests, the engine operated on fuels shown in following Table 1. Tab.1: Used motor fuels 1 Diesel oil (ÈSN EN 59 or ÈSN ) NM 2 Rape oil methyl esters (ÈSN ) BIOFUEL Miture of 95% of water-free bioethanol and 5% and AVOCET (ICI) additive EOH Method of emission finding The engine installed in tractor is loaded on P.T.O.-shaft by P - 2 manufactured by M & W hydraulic dynamometer. Measurement of concentration of NO,CO and CH gaseous harmful substances is carried out in mode of 1 th -points test determined by EHK 49 Rev. 1/1 regulation. Engine operation modes are determined by motor speed and turning moment share at outer speed characteristic and respective speed. At every mode, the values defined by EHK 49 regulation (Fig.1) are measured. Fig.1: EHK 49R 1 th poinds test mode (1 to 1 poinds charakterize mode of motor operation) 65

3 Smokiness measurement is carried out at modes of outer speed characteristic in speed of range of 1. up to 2.2 min. -1, according to EHK 24 regulation, Rev.2/. 1 AVOCET - trade description of additive containing 8% of nitriester, 18% of methanol, 2% of anticorrosive and other additives;manufacturers:ici Results Results of emission and smokiness results The main results of realized measurements are shown in following Figures 2 and [Kára, 1999]. For ZETOR 771 engine operating on diesel fuel and alternative motor fuels, can present the results: 19,2 2 19,6 18 Values of emissions ( g.kwh-1) ,2 4,7 2, 4,8,7,5 biofuel (rape oil methyl ester) ethanol 95 % AVOCET (ICI) 5 % 2 NO CO CH,4 diesel oil Fig. 2: Comparison of diesel oil emissions and alternative fuels diesel oil,5 2,5,5 biofuel (rape oil methyl ester) 1 12 ethanol 95 % AVOCET (ICI) 5 % Engine speed (min-1) 22 Fig. : Values of smokiness for diesel oil and alternative fuels Smokiness (% HSU) 66

4 - values of NO specific emission in operation on diesel oil (NM) and on methyl ester (BIOFUEL) are the same approimately, in operation on EOH they were significantly lower, - CO specific emission are practically the same in operation on diesel oil (NM) and methylester (BIOFUEL), this is a half in EOH. - CH specific emission are higher rather in alternative fuels then in diesel oil (NM), the highest emissions are in EOH (icreasing compared with diesel oil about 57%). Smokiness of engine operating on diesel oil (NM) is higher, reducing about 25% is perceptible in methyl ester (BIOFUEL), bioethanol smokiness is minimum. Discusion In Fig.4 we present data on comparison of emission of diesel oil and ethanol miture with AVOCET additive in SAAB-SCANIA DSI 11 E (184 kw) adjusted engine equipped by catalist (citybus) gained in Stockholm [L 1]. Values emissions (g. kwh-1) ,5,7 4,5,1 5,2 1,5 standard fuel - diesel oil ethanol fuel + catalyst particles NO CO CH Fig. 4: Emision of ethanol fuel compared with diesel oil for drive of citybus in Stockholm The results of our measurement prove base tendence of reducing emissions in bioethanol fuel compared diesel oil. It is necessary to take into account a significant effect of motor construction and catalist application on absolute number of difference of particular fuels emissions. There is an other problem: economy of change of diesel oil by alternative fuels. Operation costs of fuel with bioethanol are higher significantly. Following from measurement and own test, the shot-time operation of ethanol with AVOCET additive in unadjusted engine is possible. But Franch and Swedish long-time eperiences show, the adujstment of diesel motor is necessary in the case of fuel with high share of bioethanol. This fact deteriorates ability of competition of this ecological friendly fuel. 67

5 Conclusion The ecological friendly characteristics of rape oil methyl ester (BIOFUEL) and mied fuel on its base (with content over % of BIOFUEL) in diesel engines are well-known (emissions, smokiness). Thanks to our accepted ta policy, the mied fuel with share of BIOFUEL (over %) is competitive, its share on total consumption of fuels to diesel engines reashed 8% in Very favourable emission characteristics of additived ethanol fuel are unknown rather. Our measurements acknowledged these priorities in unadjusted diesel engine without catalists. Good emission charcteristics are loaded by worse economy of operation. References Information materials of municipality in Tours (France) and Stockholm (Sweden) presented in 1.European Forum on motor fuels in Tours, May Gaouyer, J. P.: What has happened in Europe in the Biofuels Domain over the last two years? Proceedings 2 nd European Motor Biofuels Forum, Graz, 1996: 7-41 Kára, J. Pokorný, Z. - Andert D.: Biofuel Utilization to Vehicles propulsion in the Czech Republic. Semináø Weltenergiespar Tag, Rakousko, Wels (poster). Kára, J. - Pokorný, Z.: Biofuel utilization. Techagro 96, Brno Kára, J. et. all: Production and use of ethanol from agricultural crops - utilization, economy and legislation. Z-228, research report VÚZT 1997, 65p. Kára, J. et. all: Production and use of bioethanol from agricultural crops - utilization, economy and legislation. Z-27/II, research report, VÚZT 1999, 9p. 68