The Fuel Consumption Study on E85 with Conventional EFI Vehicle Parinya Kongsukanant and Krongkaew Laohalidanond The Sirindhorn International Thai-German Graduate School of Engineering King Mongkut s University of Technology North Bangkok Raksit Thitipatanapong National Electronics & Computer Technology Center ABSTRACT The performance of a retrofit vehicle fuelled by gasoline-ethanol mixture emphasizing on fuel consumption, energy efficiency and fuel economy was investigated in this study. Several driving tests using a retrofit passenger car with engine management system for E10 and E85 were carried out on different driving conditions. The results obtained directly from each driving test were mass of air flow rate into an engine read from mass air flow sensor and oxygen sensor. By applying mass of air flow rate in the combustion equation, the fuel consumption rate was thereafter determined. From driving tests and calculations, tests with E85 have 15 % higher fuel consumption rate (in km/l) than tests with E10, while energy efficiency (in km/mj) is not different. With respect to carbon dioxide emission, E85 is 5-10 % less than E10. From this study, it can be concluded that ethanol can used as alternative fuel in a sparkignition engine by blending with conventional gasoline. By installation of engine management system, the fuel-air compensation is effectively controlled and it will lead to the higher performance of flexible fuel vehicle. INTRODUCTION Presently, oil price in the world market tends to continuously increase influencing Thai people and Thai economy, especially domestic transportation. For this case, alternative energy has been promoted. Thailand is able to support enough ethanol to export to the world market by processing raw planted material not only carbohydrate and sugar but also cellulose and hemi-cellulose by fermenting; sugar cane, rice, corn, cassava, etc. Therefore, Thai s government has lunched the policy to promote the use of alternative energy in order to reduce oil import, by mixing ethanol in conventional gasoline, starting from; 10 % ethanol to 85 % ethanol. Transportation is the largest oil consumer. Therefore, the concept idea is to modify the engine for using ethanol-gasoline mixture; E10-E85, called Flexible fuel vehicle (FFV). As ethanol and gasoline have similar characteristics, they can be blended together; however, engines must be modified by installing engine management system to control fuel compensation. The fuel injection duration was increased to compensate the lower heating value of ethanol. If the engine is modified in appropriate way, it can reduce the amount of oil consumption and consequently oil import. Moreover, using ethanol also builds up value added of agriculture products which are used as raw material for ethanol production. Hence, engine modifying is significantly useful. The objective of this research is to experiment performance of a modified engine for using ethanol-gasoline mixture as fuel by focusing on rate fuel consumption, energy efficiency and carbon dioxide emission. Then compare these results between E10 and E85, All driving tests conducted in this study is a real driving test on-road. ETHANOL Ethanol or Ethyl alcohol is a liquid fuel from degradation of starch and sugar by enzyme. Ethanol's chemical formula is C2H5OH. Ethanol must be refined to a high purity of 99.5 % before using in gasoline engine as fuel. If there is high moisture content in ethanol, it will cause the problems to engine, e.g. corrosion at engine parts and equipments. Raw materials for ethanol production can be divided into three major categories: 1. Starch containing materials, e.g. rice, wheat, corn, barley, sorghum, cassava, potato, sweet potato etc. 2. Sugar containing materials, e.g. sugar cane, molasses, sweet sorghum, etc. 3. Cellulosic materials, e.g. rice straw, corn cobs, rice bran, wood waste, including weeds, sugar cane waste and included industrial waste such as paper plant, etc.
In Thailand sugar cane, molasses and cassava fresh are suitable to be used as raw materials for ethanol production. Since ethanol contain OH-group which is more corrosive than conventional gasoline. Corrosive properties of ethanol are prevented by using coatings that can resist corrosion on the parts and fuel tank. Other properties of ethanol compared to conventional gasoline are shown in Table 1. Table.1 Properties of fuel [1] Fuel Ethanol Gasoline Formula C 2 H 5 OH C 8 H 15 Molar C/H ratio 0.333 0.445 Molecular weight (kg/kmol) 46.07 114.18 heating value (MJ/kg) 26.9 47.1 Stoichiometric air/fuel ratio 9 14.6 Auto-ignition temperature ºC 425 257 Heat of vaporization (kj/kg) 840 305 Research octane number 108.6 88-100 Motor octane number 89.7 80-90 Freezing point ºC -114-40 Boiling point ºC 78 27-225 Density (kg/m 3 ) 785 765 2. Normally, the air/fuel ratio of gasoline is 14.612, E10 is 14.365 and E85 is 10.678 (Fig.2) [2]. Thus, engines must be modified by install engine management system to control fuel compensation in order to complete combustion (Stoichiometric Combustion λ =1). 3. As already mentioned, corrosion properties of ethanol is higher than gasoline, some parts of engine must be made from high quality materials to prevent corrosion and some parts which directly contact with ethanol must often be changed [3]. Fig.2 Relationship between air fuel ratio and fuel compensation Fig.3 Density of fuel as a function of ethanol concentration Fig.1 Relationship between the fuel mixtures with the heating value [2] From the Table 1, ethanol and gasoline have difference properties. Thus, the engines must be modified in order to suit the properties of ethanol. The main improvements for this study are as follows. From Fig.1 Show the heating value of fuel mixtures. 1. Because the heating value of ethanol is lower than gasoline, the fuel injection time was increased to compensate the lower heating value of ethanol by install engine management system. METHODOLOGY EQUIPMENTS In this study, CHEVROLET ZAFIRA 2.2 SPORT (table 2) was examined, this vehicle was modified for retrofit flexible fuel (Fig.4). Moreover, the vehicle was installed additional equipments which were mass-air flow sensor (Fig.5) and wide-band oxygen sensor (Fig.6). In addition, the signal from additional sensors and engine parameter (RPM, vehicle speed, and injector percentage) were logged via innovate SSI-4 as illustrated in Fig.7
Fig.7 Process of the signal for analyze Fig.4 Test Vehicle Table.2 vehicle specification Z 22 SE ECOTEC Type 4 cylinder 16 valves Displacement (cc.) 2.198 Bore 86 Stroke (mm.) 94.6 Compression ratio 10.0 : 1 Power (Horsepower/kW/Rpm) 144.83 / 108 / 5800 Toque (N-m/Rpm) 203 / 4000 Injection MPFI ANALYSIS The fuel consumption can be analyzed indirectly from mass air flow rate from the fact that spark ignition engine (or gasoline engine) is operated stoichiometrically combustion which mean the air to fuel ratio (AFR) is remain constant at theoretically value[4]. As shown in equation (1) is indirectly estimate of fuel volume flow rate (FFRV) in liter/second. The fuel consumption rate is shown in equations (2) which normally ratio between distance over fuel consume. (1) (2) In this study, Both E85 and E10 were compared, so for E85 AFR=10.678 and ρ=781g/m 3 and E10 AFR=14.365 and ρ=742g/m 3. Furthermore, the energy efficiency was estimated from equation (3). Fig.5 Mass air flow sensor (MAF) (3) In addition, the CO 2 emissions is estimated from carbon-balance equation with completed combustion between gasohol (E10) and air as shown in equation (4) and the rate of CO 2 emissions is simplified as equation (5) and (E85) in equation (6) and (7) respectively. E10 0.9[C 8 H 15 ]+0.1[C 2 H 5 OH]+10.875([O 2 ]+3.76[N 2 ]) Fig.6 Oxygen sensor (AFR Sensor) 7.05[H 2 O] + 7.4[CO 2 ] + x[n 2 ] (4)
E85 0.15[C 8 H 15 ]+0.85[C 2 H 5 OH]+4.3125([O 2 ] (5) Furthermore, the energy consumption was shown in (Fig.9). Although, the fuel consumption rate for E85 was less than E10 at same constant speed, the energy consumption for E85 was remained same rate as E10 at constant speed. It is obvious that both fuels operate at same energy conversion efficiency for this vehicle. +3.76[N 2 ]) 3.675[H 2 O]+2.9[CO 2 ]+x[n 2 ] (6) (7) Where: FCR = fuel consumption rate (km/l) η Energy = energy efficiency (km/mj) CO 2 = carbon dioxide emission (g/km) VSS = speed of vehicle (Hz) to (km/h) MAF = mass air flow (g/s) λ = lamda (Oxygen Sensor) AFR = air/flow ratio ρ = density of fuel (g/m 3 ) HHV = E10=46.52, E85=37.49 (MJ/kg) RESULTS Fig.9 The energy consumption From the fact that E85 contain less carbon than E10 so that ethanol fuel has less emission. As analysis illustrated in (Fig.10), the E85 was emitted less CO 2 than E10 for all range which reduced by approximately 10%. The rate of fuel consumption, comparison between E10 and E85 at constant speed, was illustrated in (Fig.8). With the vehicle profile, at low speed, the fuel consumption rate was better than high speed for both fuels. For E85, the rate of fuel consumption was between 7.9 km/l and 5.7km/l and for E10, it was between 8.6 km/l and 7.1 km/l. Furthermore, the E85 fuel had bad fuel consumption rate than E10 by about 15% as expected from less energy content in the fuel. To be comparative, the energy consumption was considered. Fig.10 Carbon dioxide emission CONCLUSION REMARK Fig.8 Fuel consumption rate In this study, the retrofit flexible fuel vehicle was investigated for fuel consumption and carbon dioxide emission. Although, the fuel consumption rate for E85 fuel was lesser, the energy consumption was same as E10. Therefore, the carbon dioxide emission was reduced. In conclusion, the E85 fuel could be feasible to apply in conventional vehicle with retrofit kit.
ACKNOWLEDGEMENT This study has financial support from National Science & Technology Development Agency (NSTDA) in Service Research Innovation Program. REFERENCES 1. Tanawat Sriraksa and Chinda Charoenphonphanich, Ethanol Fuel Motorcycle, (in Thai)The 22 rd Conference of themechanical Engineering Network of Thailand (ME-NETT22), 2551, AEC 030. 2. Jarut Kunanoppadon, Air-Fuel ratio and combustion energy analysis of gasohol, (in Thai)The4 th Conference on Energy Network of Thailand (E-NETT), 2551. 3. Kalong Buanak, Panya Kansuwan, Chinda Charoenphonphanich, The investigation of ethanol fuel and E85 impacts on fuel supply system: Material compatibility test, (in Thai)The 23 rd Conference of the Mechanical Engineering Network of Thailand (ME-NETT23), 2552, AEC-021153. 4. Raksit Thitipatanapong and Thanud Luangnarutai, A Driving Condition Acquisition and Analysis: Vehicle Fuel Consumption,(inThai)The24 rd Conference of the Mechanical Engineering Network of Thailand (ME-NETT24), 2553, ETM031. CONTACT Raksit Thitipatanapong, M.Sc. is a research engineer working on driver behavior analysis for safety & saving at Telemetric Engineering section, National Electronic & Computer Technology Center, Thailand. Email: raksit.thi@nectec.or.th