Seetar G. Pande

A practical evaluation of published cetane indices

Abstract Six published cetane indices were comparatively evaluated using a per cent predictability method, which was both rigorous and practical. The conventional linear regression analysis method was also employed. The indices evaluated included ASTM D976-80, ASTM D4737-87 (the proposed replacement of ASTM D976-80), the National Research Council of Canada (NRCC) cetane index, the Canadian General Standards Board cetane index (CGSB), the Calculated Carbon Aromaticity Index (CCAI), and the Ethyl equation. The fuel set, which was obtained from a worldwide survey, comprised 63 fuels and included only those fuels that met the application range specified by ASTM D4737-87 (the index which was most restrictive towards fuel properties). Cetane numbers of the fuels ranged from ≈ 45 to 57, with one fuel having a cetane number of 37. For the fuel set examined, based on the criteria imposed for determining predictability, the following were observed: ASTM D4737-87 exhibited a tendency to overpredict and did not appear to be an improvement over ASTM D976-80; both the NRCC and the CGSB cetane indices exhibited a tendency to underpredict; and a modified CCAI equation appeared promising as a predictor of cetane number.

Flammability and storage studies of selected fire-resistant fluids

Using the Naval Research Laboratorys mist flammability apparatus, several commercial samples of invert water-in-oil emulsions, designed for possible application as fire-resistant hydraulic fluids or lubricants, were screened for fire resistancy. Their stabilities under storage conditions for approximately a 2-year period were also assessed. For comparison purposes, two other commercial fire-resistant fluids were also screened, viz. a water-glycol solution and a phosphate ester. The Navys current petroleum type hydraulic fluid, 2190-TEP, was employed as the reference fluid. In addition to fire resistancy tests, the drop size distributions of water microdroplets in the separated emulsion layers were also determined.

Evaluation of refractivity intercept as a method for determining fuel composition according to hydrocarbon type

Abstract A recently published refractivity intercept (Ri) method for determining the composition of petroleum distillates was examined for model jet fuels. Based on five model jet fuels of diverse compound class composition, at best, the Ri method predicted the composition of only one of the five fuels within an accuracy of ± 26%. Limited improvement was obtained on employing Ri coefficients derived from the various model mixtures examined. Poor predictability of the Ri method is likely related to the erroneous assumption that Ri, as defined, is additive for the compositionally defined classes of interest. In addition, the methodology requires a high degree of accuracy in measuring both density and refractive index.

Fire-inhibiting behavior of high molecular weight polyisobutylene in JP-5 jet fuel

The fire-inhibiting behavior of polyisobutylene (PIB) solutions in JP-5 jet fuel has been examined using a rotating disk mist generator combined with an ignition source. The correlation of the mass median diameters (MMD) of fuel mists with their fire-inhibiting behavior is discussed and a preliminary analysis of the data usinf the concept of an antimisting factor, in analogy to earlier drag reduction work, is attempted. The effect of molecular weight on the MMD is also presented. The concentration dependence of the MMD for PIB solutions in JP-5 is compared with a proprietary fire-inhibiting formulation.