Engine behavior using mixtures of gasoline - ethanol

Transcription

1 RECENT ADVANCES in ENERGY & ENVIRONMENT Engine behavior using mixtures of gasoline - ethanol CHARALAMPOS ARAPATSAKOS Department of Production and Management Engineering Democritus University of Thrace V. Sofias Street, 671, Xanthi GREECE xarapat@agro.duth.gr Abstract: -One of the greatest contributors to air pollution in large cities is the transportation sector. The emissions from the increased number of vehicles contribute to smog, low visibility and various greenhouse gas emissions. Pollutants contributing to smog come from a variety of sources, including vehicle emissions, smokestack emissions, paints and solvents. Particularly in the summer time, smog and ground level ozone can contribute to respiratory problems ranging from temporary discomfort to long lasting permanent lung damage. This work deals with the examination of a two stroke engine s behavior, which is used to operate electricity producing small power generator, taking into consideration the following factors: normal running, power and consumption. Key-Words: - Gas emissions, ethanol 1.INTRODUCTION Furthermore, diesel emissions have the potential to cause adverse health effects, such as cancer and other pulmonary and cardiovascular diseases. Ethanol is a liquid alcohol that is produced from the fermentation of grains such as wheat, barley, corn, wood, and in Brazil, sugar cane. Fermentation is a reaction in which zymase (an enzyme from yeast) changes simple sugars into ethanol and carbon dioxide. This reaction has also by-products: glycerine and various organic acids. The process of changing grains to sugar and changing sugar to ethanol is a complex process and requires technologies such as microbiology, chemistry and engineering. Ethanol can be used as an alternative to unleaded gasoline. Ethanol is used as an automotive by itself and can be mixed with gasoline to form mixtures that contains 1% ethanol or 85% ethanol mixed with gasoline. This mixture is a high-octane with high oxygen content that can produce a more complete combustion resulting in fewer emissions [1]. There are many advantages of using ethanol as an automotive. First of all it reduces pollution when is used with gasoline, and by adding oxygen to the combustion process that reduces exhaust emissions. The use of ethanol results in reductions of many pollutants, including ozone, air toxins, carbon monoxide, particulate matter, and nitrogen oxides. The use of 1% ethanol in a mixture with 9% gasoline causes a 25% to 3% reduction in emissions of carbon monoxide (CO). Despite the fact that carbon dioxide (CO 2 ) is produced from the procedure of fermentation, the use of ethanol in gasoline may result in a net reduction in atmospheric carbon dioxide levels. Moreover, ethanol is low in reactivity and high in oxygen content, making it an effective tool in reducing the ozone-forming emissions such as carbon monoxide and hydrocarbons when ethanol is used in a mixture with gasoline. Ethanol can also replace toxic octane enhancers in gasoline such as benzene, toluene and xylene. Another important advantage of ethanol is its contribution to the economic development. Namely, ethanol is a cheap activity, as it is produced from plants and therefore many new jobs can be created in the agricultural for unemployed people. Important quantities of ethanol are produced every year to be used as [2]. Ethanol has a high octane value, which means that it can be used as a additive, or as a substitute either as pure alcohol or as mixture of gasoline-alcohol. There are many ways to produce Alcohol in the laboratory. There is practical interest in producing ethanol from plants that are rich in sugar. Alcoholic fragmentation is the splitting of single sugars, type ISSN: ISBN:

2 C 6 H 12 O 6, mainly glucose and fructose, to CO 2 which is catalysed by the zymasse enzyme. Raisins, molasses and starchy roots or fruits like potatoes, corn, barley and others are used for this purpose. Nowadays mixtures of gasoline - alcohol are used in USA mainly as car (gasohol), either to fight the energy crisis or to decrease environmental pollution, because of the limited CO, HC emissions. Compared to pure gasoline, the gasoline-alcohol mixtures produce smaller calorific output. This is why the use of these mixtures in petrol engines reduces the power of the engine. The power decrease, in principle, increases in proportion to the alcohol percentage in gasoline. The main pollutants emitted from internal combustion engines are carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NO x ) and particulate matter. Carbon Monoxide reacts with hemoglobin while forming carboxyhemoglobin and reduces the oxygencarrying capacity of the blood [1,2]. Also, carbon monoxide can be converted to carbon dioxide (CO 2 ) when it reacts with hydroxyl radical (OH) [2]. Carbon dioxide contributes on global warming of the atmosphere (greenhouse effect) causing long-term damage to the environment [3]. Incomplete combustion and evaporation of the s releases hydrocarbons to the atmosphere. Some hydrocarbons such as benzene and 1,3-butadiene are toxic and can cause cancer to humans [2]. Reactive hydrocarbons can contribute to ozone production [4]. Nitrogen oxides contribute to photochemical smog and also can cause human respiratory problems. Furthermore, when nitrogen oxides combine with water produce acids which mean that can contribute to acid rain formation [4]. The size of the particulate matter is important on the health effect that has on humans. When particulates are very small they are not filtered at the nose and can travel into the lungs causing tissue damage [1]. The large increases in the price of crude oil, the important changes in oil market, the finite of reserves as well as the envinomental pollution led to the revaluation of the importance of the rural and forestal factor as a renewable resources supplier. Important quantities of ethanol are produced every year to be used as [1]. Nowadays mixtures of gasoline - alcohol are used in USA mainly as car (gasohol) to fight the energy crisis and simultaneously to decrease environmental pollution, because of the low CO, HC emissions that they occur. Compared to pure gasoline, the mixtures of gasoline-alcohol present smaller calorific value [3]. This is why, the use of these mixtures in petrol engines causes a decrease in the power of the engine [2,4]. The power decrease, in four stroke engines, increases in proportion to the alcohol percentage in gasoline [5]. The question that arises is how a two stroke engine behaves when mixtures of gasoline alcohol are used. RECENT ADVANCES in ENERGY & ENVIRONMENT 2.INSTRUMENTATION The tests were realized on a two stroke engine, type YAMAHA ET-5 cylinder 49cm 3, carburetor engine, which is used for the operation of an alternative current generator with the following characteristics: AC output 5VA-4VA Frequency 5Hz Voltage 22-24V Phase Single For the measurement of exhaust gases, an exhaust analyser was used, type HORIBA MEXA 574E infrared radiation (Non Dispersive Infra Red) with measuring cylinder for CO from to 1% and for HC from ppm to 1.ppm. To observe the output voltage a palmograph was used, type HITACHI VC- 623 Digital Storage oscilloscope, which was connected to a computer, type AT MHz, where the output voltage was registered through a special program. Three series of tests were held. In order to achieve the best and most accurate examination of the engine, through exhaust gases (HC, CO) measurements, output voltage measurements (with different power ohm loads) and finally through consumption measurements (using different gasoline - alcohol mixtures). In the first series of tests, 12 tests were carried out, using different gasoline-alcohol mixtures (of 95 alcoholic degrees), keeping the oil quantity stable, at 1:5. More specifically, the following tests were carried out using the mixtures below: mixture of pure gasoline (super), mixture of 9% gasoline (super) -1% ethanol in volume, mixture of 8% gasoline (super) -2% ethanol in volume,. mixture of 7% gasoline (super) -3% ethanol in volume. For each of the tests above, were used different power ohm loads of W-1W-2W-32W, being in parallel connection at the generator output, where continuous registration of CO and HC was made for each mixture and ohm load separately. The second series of experiments dealed with the registration of the generator s output voltage. The third series of experiments examined the consumption, which was measured separately for each mixture, always in relation to the different power ohm loads. The environmental conditions, for all the testing s above, were 2 C (temperature) and 1atm (pressure) with negligible variations. ISSN: ISBN:

3 RECENT ADVANCES in ENERGY & ENVIRONMENT EXPERIMENTAL RESULTS On table 1 are given the average values of CO and HC in relation to power ohm load and ethanol percentage in the. gasoline 1% 2% 3% W CO HC CO HC CO HC CO HC %vol (ppm) %vol (ppm) %vol (ppm) %vol (ppm),44 345,32 365,26 418, ,8 31,4 328,22 379, ,36 293,51 313,18 362, ,8 38,69 316,14 359,9 395 H C (p p m ) SUPER Watt 1% 2% 3% Table 1. Average values of exhaust gases for each mixture, in relation to power ohm load. The graphics of these results are given below: C O % v ol SUPER 1% 2% 3% Watt Figure 1. Variation of CO in relation to power ohm load for different mixtures. Figure 2. Variation of HC in relation to power ohm load for different mixtures. On figure 1, it can be noticed a decrease in CO percentage with increase in ethanol percentage in gasoline. On figure 2, where a change of HC occurs, two phenomenons are noticed. The first phenomenon is that by increasing the ethanol percentage in the, there is also an increase in HC. The second phenomenon is that, for a certain mixture, it has been noticed a decrease in hydrocarbons, by increasing the power ohm load from W up to 2W, as well as an increase in hydrocarbons, by increasing power ohm load from 2W up to 32W. The first phenomenon is probably due to the aldehyde production, during ethanol s combustion, which increases in proportion to alcohol percentage. The second phenomenon is probably due to the fact that the increase of power ohm load causes a decrease in the engine s rpm and an increase in the combustion temperature. This increase, however, results in further fragmentation of aldehydes to CO 2 and H 2 O that is the decrease of HC with the increase in load. All these happen up to 2W power ohm load. Things change as we continue: The phenomenon is inverted and it is observed an increase in HC by increasing the load. This can be justified if we consider that the load increase from 2W to 32W is accompanied by the combustible increase. In this increased combustible quantity we have a greater quantity of alcohol and therefore a greater water quantity too, since the alcohol which was used was 95 alcohol degrees. And so, the small calorific value of alcohol and the larger quantity of water, avert the aldehyde combustion to CO 2 and H 2 O, and either decrease or stabilize the combustible temperature. The purpose of the second series of experiments, which follows, is to make it clear, through registration of output voltage, how the increase in ISSN: ISBN:

4 alcohol percentage in gasoline affects the operation of the petrol engine. This is clearly shown on the following diagrams: 2 RECENT ADVANCES in ENERGY & ENVIRONMENT Super 1% 2% 3% Figure 3. Output voltage variation without power ohm load, in relation to the different mixtures of, for the research time -5ms. 2 Super 1% 2% 3% Figure 4. Output voltage variation with power ohm load 1W, in relation to the different mixtures of, for the research time -5ms ISSN: ISBN:

5 RECENT ADVANCES in ENERGY & ENVIRONMENT 2 Super 1% 2% 3% Figure 5. Output voltage variation with power ohm load 2W, in relation to the different mixtures of s, for the research time -5ms. 2 SUPER 1% 2% 3% Figure 6. Output voltage variation with power ohm load 32W, in relation to the different mixtures of s, for the research time -5ms. ISSN: ISBN:

6 In figure 3, we can see the output voltage variation without power ohm load, in relation to different mixtures of s, at the research time from to 5ms. Obviously, for none of the four cases of, pure gasoline (Super), mixture of 9% gasoline (Super)-1% ethanol in volume, mixtures of 8% gasoline (Super)- 2% ethanol in volume and mixture of 7% gasoline (Super)-3% ethanol 3% in volume, the output voltage is affected by the type of. This fact reveals that the presence of ethanol in the does not affect the operation of the two stroke engine motor. The same thing is observed in figures 4 and 5. Things change in figure 6, where the variation of output voltage, during the parallel connection of power ohm load of 32W, is displayed, having used different mixtures of gasolineethanol. We noticed that there isn t any voltage variation during the use of the following mixtures as a : pure gasoline (Super), mixture of 9% gasoline (Super)-1% ethanol in volume, mixtures of 8% gasoline (Super)-2% ethanol in volume and mixture of 7% gasoline (Super)-3% ethanol 3% in volume, where a voltage decrease is noticed. This voltage decrease is due to the motor rpm decrease, which is a result of the small calorific value of the. This voltage decrease is then observed during the connection with the power ohm load 32W, and not with the load of 1W and 2W, as the amount of, that is drained in the combustion chamber, is greater than that of the load of 1W and 2W. Regarding to the calorific value, it s lower than in the rest of the mixtures causing, this way, a decrease in the combustion temperature, due to the greater amount of alcohol and water in the, and therefore a decrease in the power of the two stroke gasoline motor. The results of the third series of experiments, concerning the combustion of the gasoline motor in relation to the load and the, are displayed in Table 2. W 1W 2W 32W % ethanol pure 5 5,6 6,4 7,3 gasoline 1% 5,4 5,9 6,5 7,5 2% 5,8 6,2 6,7 7,7 3% 6,1 6,3 6,9 9,9 Table 2. Fuel supply in relation to the load and the ethanol percentage. The consumption of gasoline motor increases in proportion to the alcohol percentage in the and to the power ohm load, a fact which shows that in order to maintain a stable generator output voltage, during the use of gasoline-alcohol mixtures, the amount of should be increased. This, as it has been previously referred, is the result of the low calorific value which appears in those mixtures. RECENT ADVANCES in ENERGY & ENVIRONMENT 4. CONCLUSIONS There are many advantages of using ethanol as an automotive. First of all it reduces pollution when is used with gasoline, and by adding oxygen to the combustion process that reduces exhaust emissions. The use of ethanol results in reductions of many pollutants, including ozone, air toxins, carbon monoxide, particulate matter, and nitrogen oxides. On the four stroke engine the ethanol percentage increase in the (up to 3% in volume) results in the exhaust gases (HC and CO) decrease, as well as in the consumption increase [2]. However, the use of gasoline-ethanol mixtures in the case of two stroke engine, results in the decrease of CO and the increase iof HC, by increasing the ethanol percentage in the. Then, the increase in alcohol percentage in the doesn t affect the gasoline engine s operation except for the case of the mixture 7% gasoline (Super) - 3% ethanol in volume, where the irregular operation of the gasoline engine is obvious. Finally, considering the consumption, it is observed that the increase in the alcohol percentage in the results in the consumption increase. The ethanol s low cost, renders its use suitable as a mixture with gasoline, even in low power two stroke engines. REFFERENCES: [1]. M. Kirik, Alcohol as an Alternative Fuel The Ontario Digest and Engineering Digest, pp.29-31, September [2]. Charalampos I. Arapatsakos and Panagiotis D. Sparis. Bioethanol - Premium Gasoline Mixture Tests in Otto Engines Meeting of the Greek Section of Combustion Institute, November 1997 Zappio Megaro,Athens. [3]. Swedish Motor Fuel Technology Co., Alcohols and Alcohol Blends as Motor Fuel, Vol IIB, p. 8:39, STU Information No. 58, [4]. R.M Tillman, Blending, Distribution and Marketing Aspects of Alcohols as Alternative Fuels Ontario, November 19, [5] Koening H Menrad and W. Bernhardt, Alcohol Fuels in Automobiles Alcohol Fuel Conference, Inst. Chem. Eng., Sydney, 9-11 August 1978 ISSN: ISBN: