Abstract
Measuring the ethanol/water ratio in biofuel of high ethanol content, such as E85, is important when used in a flex-fuel engine. A capacitive probe is generally used for measuring the ethanol/gasoline ratio. However, the water content in E85 biofuel cannot be disregarded or considered constant and full composition measurement of biofuel is required. Electric impedance spectroscopy with a customized coaxial probe operating in the 10kHz to 1MHz frequency range was investigated. An in-depth investigation of the electrical impedance domain has led to the conclusion that additional information is required to unambiguously determine the composition of the ternary biofuel mixture. Among the different options of measurement domains and techniques, optical absorption spectroscopy in the UV spectral range between 230 and 300nm was found to be the most appropriate. The typical absorbance in the UV range is highly dominated by gasoline, while ethanol and water are almost transparent. This approach is experimentally validated using actual fuels.
Highlights
Bio-ethanol has been introduced as a renewable source of energy in an attempt to reduce our ‘carbon footprint’
The poor repeatability of the conductance measurements is consistent with literature and is due to: a complex temperature dependence, an ethanol sample dependency, high sensitivity to free ions/contamination and the influence of static dissipaters [8,25]. These results indicate that only the capacitive part of the impedance can be practically used for measuring biofuel composition
The additional information that is required to unambiguously determine the composition of the ternary mixture cannot be retrieved by impedance spectroscopy for two reasons
Summary
Bio-ethanol has been introduced as a renewable source of energy in an attempt to reduce our ‘carbon footprint’. In Europe the standard low-ethanol content type of biofuel obtainable at the gas station is typically conventional gasoline mixed with 10% bio-ethanol by volume (referred to as E10 fuel). A commercially available capacitive sensor is produced by Continental [12,13] This sensor measures the capacitance at a low frequency (10 kHz) and the information is used for determining the ethanol/gasoline fractions in a binary mixture. According to the ANP (National Agency of Petroleum, Natural Gas and Bio-fuels, Brazil) AEHC must have an ethanol content between 92.6 and 93.8 INMP (which refers to mass content) [15] When we translate these values into volume fractions, AEHC must contain between 94.1 and 95◦ GL (Degree Gay-Lussac) alcohol by volume at 15◦ C (59◦ F), which implies that the maximum water fraction is equal to 5.9%. As is indicated the spectral signature is not very distinctive and the resistive part of the impedance is insufficiently reproducible to ensure a reliable measurement of the full composition of the biofuel
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
