Fuel Property Determination of Biodiesel-Diesel Blends By Terahertz Spectrum
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Fuel Property Determination of Biodiesel-Diesel Blends By Terahertz Spectrum Hui Zhao & Kun Zhao & Rima Bao
Received: 20 November 2011 / Accepted: 5 March 2012 / Published online: 27 March 2012 # Springer Science+Business Media, LLC 2012
Abstract The frequency-dependent absorption characteristics of biodiesel and its blends with conventional diesel fuel have been researched in the spectral range of 0.2-1.5 THz by the terahertz time-domain spectroscopy (THz-TDS). The absorption coefficient presented a regular increasing with biodiesel content. A nonlinear multivariate model that correlating cetane number and solidifying point of bio-diesel blends with absorption coefficient has been established, making the quantitative analysis of fuel properties simple. The results made the cetane number and solidifying point prediction possible by THz-TDS technology and indicated a bright future in practical application. Keywords Terahertz time-domain spectroscopy . Cetane number . Solidifying point . Bio-diesel blends
1 Introduction In recent years, there is much attention on biodiesel, the alternative source of petroleumbased fuel. Biodiesel is produced by a relatively simple reaction known as transesterification, where natural oils and fats made up mainly of triglycerides react with a simple alcohol, such as methanol or ethanol, in the presence of a catalyst to produce mono alkyl esters of fatty acids, which is biodiesel [1–4]. It presents some advantages, such as non-toxic, renewable energy, biodegradable, high flash point and less polluting gas emissionsen, etc. The physical chemical characteristics of biodiesel are similar to those of common diesel, so that biodiesel and its blends with conventional diesel fuel were always used in diesel engines without significant modification on the engine [5–7]. Cetane number (CN) and solidifying point (SP) are prime indicators of fuel quality in diesel engines, which have been described as measures of its ignition delay time and low temperature flow property. American society of testing materials (ASTM) defines the CN of H. Zhao : K. Zhao (*) : R. Bao Laboratory of Optic Sensing and Detecting Technology, College of Science, China University of Petroleum, Beijing 102249, China e-mail: [email protected]
J Infrared Milli Terahz Waves (2012) 33:522–528
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a diesel fuel as the percentage by volume of normal cetane (C16H34), in a blend with 2,2,4,4,6,8,8-heptamethylnonane (sometimes called HMN or isocetane), which matches the ignition quality of the diesel fuel being rated under the specified test conditions, measured in a specially designed test engine (ASTM D613) or in a constant volume combustion apparatus (ASTM D6890) [8–10]. The SP is the temperature in which diesel has no fluid properties and always be measured by GB/T510-83 standard method [11]. However, these tests are awkward and expensive. For this reason there have been many attempts to develop methods to estimate the indexes economically, rapidly and effectively. In this letter, terahertz spectroscopy has been used to research t
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