Article Cite This: J. Chem. Eng. Data XXXX, XXX, XXX−XXX
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Viscosity of Cottonseed Oil and Biodiesel Nieves M. C. Talavera-Prieto,*,†,‡ Abel G. M. Ferreira,† António T. G. Portugal,† and Ana P. V. Egas† †
CIEPQPF, Department of Chemical Engineering, University of Coimbra, Polo II, Rua Silvio Lima, 3030-970 Coimbra, Portugal CECOAL-CONICET-UNNE, Ruta 5 Km 2.5, 3400 Corrientes, Argentina
‡
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ABSTRACT: The viscosities of cottonseed oil (CSO) and cottonseed biodiesel (CSB) were measured at atmospheric pressure and temperatures from (293 to 373) K and (303 to 348) K, respectively. The Vogel−Fulcher−Tammann (VFT) and Mauro (MYEGA) equations were selected to represent the temperature dependence of the experimental data, giving deviations within the experimental uncertainties. These equations allowed estimating the glass transition temperatures, which were compared with available values from literature. For viscosity prediction, the group contribution method proposed by Ceriani was compared with the fragment approach given by Zong for CSO. For CSB the Grunberg−Nissan equation coupled with Ceriani and Yuan models was applied, and the influence of the interaction parameter (Gij) is highlighted.
(VFT).5−7 The physically based equation found by Mauro et al. (MYEGA)8 was also used to account for the non-Arrhenius behavior which has been reported for oils. The predictive ability of Zong’s fragment-based9 and Ceriani’s10 models was evaluated for CSO, and the Ceriani10 and Yuan’s model revised by Freitas et al.11 was applied to CSB. The importance of using interaction contribution parameters in the Grunberg and Nissan12 equation to describe the viscosity of CSB was quantitatively studied.
1. INTRODUCTION Viscosity is one of the most important properties of a biodiesel that must be in accordance with quality standards (EN 14214 and ASTM D6751). Viscosity and surface tension affect the spray quality of fuels in direct-injection diesel engines. Fuels with high viscosity tend to form larger droplets upon injection, which may result in a poor fuel atomization, increasing the engine deposits and affecting the quality of fuel/air mixture and, consequently, the exhaust emissions from the engine. It is also important to verify the viscosity behavior with temperature variation since an increase in temperature between the fuel pump and the fuel injector is expected, thus affecting the injection system design. Transesterification reduces the viscosity of the oil, making it more similar to diesel and improving other important characteristics for proper combustion in a diesel engine. Moreover, in the synthesis process, the knowledge of viscosity is of great importance. Design of pipes, reactors, pumps, mixers, settlers, and other equipment involved in biodiesel production is highly dependent on the viscosity of both oil and biodiesel. The viscosity of CSO has been measured by different authors with different methodologies and with different purposes. Beyond the measurements made by several authors at one temperature, viscosity data as a function of this variable are due to Macovei,1 Eryilmaz et al.,2 and Wakeham and Magne.3 The viscosity data of CSB is scarce from the literature. The few studies over extensive ranges of temperature were made by Eryilmaz et al.2 and Nogueira et al.4 This work aims to provide experimental viscosity data of CSO and CSB at atmospheric pressure and temperatures in the range T = (293 to 373) K and T = (303 to 348) K, respectively. One of the most used equations to correlate oil and biodiesel viscosity data is the Vogel−Fulcher−Tammann © XXXX American Chemical Society
2. EXPERIMENTAL SECTION 2.1. Materials. The detailed specifications of the CSO used in viscosity measurements are summarized in Table 1. The details of CSO transesterification to produce the biodiesel and its characterization were given in our previous paper.13 The molar and mass compositions of CSO and CSB are presented in Table 2. 2.2. Viscosity Measurements. Dynamic viscosity measurements of CSO were made over the temperature range (293 to 373) K at atmospheric pressure using a Brookfield Thermosel system with a rotational DV-II+ (model LVDVII) viscometer. Temperature was controlled to better than 0.01 K, which was considered as the uncertainty of temperature measurements. The stirring action of the rotating spindle, plus the small sample volume, helped to keep the temperature gradient across the sample to a minimum. For each measurement, the temperature was measured by a platinum resistance thermometer ERTCO-Eutechnics High Precision Digital Thermometer certified in the ITS90 with an Received: November 16, 2018 Accepted: February 14, 2019
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DOI: 10.1021/acs.jced.8b01087 J. Chem. Eng. Data XXXX, XXX, XXX−XXX
Journal of Chemical & Engineering Data
Article
Table 1. Fatty Acid Composition and Properties of CSO material cottonseed oil
supplier Acros Organics
CAS no.
sample puritya (wt %)
propertiesb
17711
fatty acid composition: MeC14:0 and lower, ca. 1.5%; MeC16:0, ca. 25%; MeC18:0, ca. 3%; MeC18:1, 16 to 24%; MeC18:2, 50 to 55%; MeC18:3 and higher,
