Studies of Jet Fuel Freezing by Differential Scanning Calorimetry

Abstract

Differential scanning calorimetry (DSC) was used to study the freezing of jet fuel and the effect of cold flow improving additives. We find that the cooling (freezing) exotherm is a more useful diagnostic tool for this purpose than the heating (melting) endotherm. Jet fuels (Jet A, JP-8, and Jet A-1) display a strong exotherm upon cooling between −45 and −60 °C. By the study of mixtures composed of classes of jet fuel components (normal paraffins, isoparaffins, and aromatics), we find that the cooling exotherm is primarily due to the liquid−solid phase transition of the normal paraffins. Cold flow improving additives (e.g., pour point depressants) show only small effects on the DSC exotherm despite larger effects observed in cold flow devices. This indicates that these additives work primarily by affecting the habit of the n-alkane crystals. This change in crystal habit is supported by low-temperature microscopy studies.

Toward low-cost biological and hybrid biological/catalytic conversion of cellulosic biomass to fuels

“…In comparison, the enthalpy of fusion for C10 isoalkanes, cycloalkanes, and aromatics is below 20 kJ mol −1 . 377 However, crystallization also depends on the composition of the non-crystallizing components of the solution in complex ways. 378 The presence of polar oxygen functional groups on an alkyl chain increases the freezing point and reduces solubility (note the following melting points, dodecane: −9.6 °C, 2-dodecanone: 20 °C, dodecanol: 24 °C, dodecanoic acid: 43.2 °C), while the less polar ester group can have little effect (methyl undecanoate: −10 °C).…”

Dual Action Additives for Jet A-1: Fuel Dehydrating Icing Inhibitors

“…It has been previously used to study the phase change characteristics of Fuel System Icing Inhibitors [37], and jet fuels with and without additives [30]. The freezing point of neat DiEGME is -70 °C [37].…”

Feasibility Study for Production of Biofuel and Chemicals from Marine Microalgae Nannochloropsis sp. Based on Basic Mass and Energy Analysis

“…Figures 6 and 7 show that there appears to be no glass transitions and crystallization behavior for any of the biooil products. Studies have reported [24] that the presence of aromatics exhibits a crystallization behavior but the bio-oil products obtained from pyrolysis of algae biomass (with and without lipids) did not exhibit such behavior.…”

“…The bio-oil produced via pyrolysis of wood biomass is generally composed of aromatics, saturated carbons, alcohols, amines, and acids. Studies have suggested [24] that the aromatics group of compounds show glass transition behavior.…”