Fuel Heat of Vaporization Values Measured with Vacuum Thermogravimetric Analysis Method

Zhou, Guangci; Roby, S. H.; Wei, Tao; Yee, Nay

doi:10.1021/ef402491p

Cited by 8 publications

(8 citation statements)

References 11 publications

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“…Calculating the enthalpy of vaporization based on a volume basis (as discussed by Chupka et al 45 ) shows that the two blends have near-identical values in the region of 311.6-314.0 kJ/L (M15 being 0.7% higher) although the value for the mixture is also dependent on the composition of the gasoline (for which 280 kJ/kg has been used here). (Note that there is an alternative view that mass-based enthalpy of vaporization should be used, as proposed by Zhou et al 46 Adopting this approach, E20 would have an enthalpy of vaporization of 417.4 kJ/kg and M15 421.9 kJ/kg; that is, using this calculation approach that of M15 is 1.1% higher. Note also that these values are approximately 50% higher than the value of 280 kJ/kg used for the gasoline.)…”

Section: Binary Gasoline-alcohol Blend Tests In the Ultraboost Extremmentioning

confidence: 99%

Alcohol fuels for spark-ignition engines: Performance, efficiency and emission effects at mid to high blend rates for binary mixtures and pure components

Turner

Lewis

Akehurst

et al. 2018

Proceedings of the Institution of Mechanical Engineers, Part D:

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The paper evaluates the results of tests performed using mid-and high-level blends of the low-carbon alcohols, methanol and ethanol, in admixture with gasoline, conducted in a variety of test engines to investigate octane response, efficiency and exhaust emissions, including those for particulate matter. In addition, pure alcohols are tested in two of the engines, to show the maximum response that can be expected in terms of knock limit and efficiency as a result of the beneficial properties of the two alcohols investigated. All of the test work has been conducted with blending of the alcohols and gasoline taking place outside the combustion system, that is, the two components are mixed homogeneously before introduction to the fuel system, and so the results represent what would happen if the alcohols were introduced into the fuel pool through a conventional single-fuel-pump (dispenser) approach. While much has been written on the effect of blending the light alcohols with gasoline in this way, the results present significant new findings with regard to the effect of the enthalpy of vaporization of the alcohols in terms of particulate exhaust emissions. Also, in one of the tests, two mid-level blends are tested in a highly downsized prototype engine -these blends being matched for stoichiometry, enthalpy of vaporization and volumetric energy content. The consequences of this are discussed and the results show that this approach to blend formulation creates fuels which behave in the same manner in a given combustion system; the reasons for this are discussed. One set of tests using pure methanol alternately with cooled exhaust gas recirculation and with excess air shows a significant increase in thermal efficiency that can be expected as the blend level is increased. The effect on nitrous oxide emissions is shown to be similarly beneficial, this being primarily a result of the enthalpy of vaporization of the alcohol cooling the charge coupled with the lower adiabatic flame temperature of the alcohol. Whereas it is normally a beneficial characteristic in spark-ignition combustion systems, one disadvantage of a high value of enthalpy of vaporization is shown in another series of tests in that, in admixture with gasoline, it is a driver on flash boiling of the hydrocarbon component in the blend in direct injection combustion systems. In turn, this causes the particulate emissions of the engine to increase quite markedly over those of ethanol-gasoline blends at the same stoichiometry. The paper shows for the first time the dichotomy of the potential efficiency improvement with the challenge of particulate control. This effect poses a challenge for the future introduction and use of such high blend rate fuels in engines without particulate filters. Although it must be stated that the overall particulate emissions of the methanolgasoline blend are lower than for gasoline, the effect is only present at extremely low load, and that there is a likelihood that particulate filters will be adopted in production vehicle anyway...

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Section: Binary Gasoline-alcohol Blend Tests In the Ultraboost Extremmentioning

confidence: 99%

Alcohol fuels for spark-ignition engines: Performance, efficiency and emission effects at mid to high blend rates for binary mixtures and pure components

Turner

Lewis

Akehurst

et al. 2018

Proceedings of the Institution of Mechanical Engineers, Part D:

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“…In some cases, vacuum is used, especially when analysing oxygen-sensitive species [8], e.g. fuels [9]. In-vacuum TGA measurements have also been applied to study early stages of metal oxidation in low-pressure corrosive atmospheres [10].…”

Section: Introductionmentioning

confidence: 99%

Vacuum versus ambient pressure inert gas thermogravimetry: a study of silver carboxylates

Jurczyk

Glessi

Madajska

et al. 2021

J Therm Anal Calorim

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A comparative study of vacuum versus ambient pressure inert gas thermogravimetry was performed on silver carboxylates compounds. Some of the complexes from this group have been previously successfully applied as precursors for both chemical vapour deposition and electron beam-induced deposition. Considerable differences were found between the thermogravimetry methods, which we associate with changes in evaporation dynamics. Vacuum thermogravimetry sublimation onsets consistently occurred at lower temperatures than ambient pressure N2-flow thermogravimetry, where the differences reached up to 120 °C. Furthermore, compound sublimation during N2-TGA was suppressed to such an extent that significant thermal decomposition of the compounds into metal and volatile organic fragments was observed while at vacuum the same complexes sublimed as intact molecules. Moreover, thermal stability of silver complexes was investigated using isothermal thermogravimetry. These findings are interesting for the field of thin film synthesis and nanomanufacturing via chemical vapour deposition, atomic layer deposition and focused electron beam induced deposition. In all three methods, delivery of functional precursor over the substrate is crucial. The presented results prove that vacuum thermogravimetry can be used as fast method of pre-screening for novel, especially low-volatility precursors. Graphic abstract

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“…7−10 For example, Zhou et al used a vacuum thermogravimetric analyzer (VTGA) to determine the HoVs for various renewable fuels from their VTGA-measured boiling points. 10 Researchers have also correlated retention times in gas chromatography to inverse vapor pressure measurements, which they then translated into HoV of components. In both cases, component HoVs were subsequently added using mole fraction weighting to obtain the mixture HoV.…”

Section: Introductionmentioning

confidence: 99%

“…Applying these predictive methods to pure components is straightforward, and simple mixing rules can be used to apply them to mixtures (where the HoVs are weighted on a mole fraction or volume fraction basis). 10 They have generally not been applied to more complex mixtures, such as military fuels, which may require more advanced calculations 29 because jet fuels can contain thousands of components whose thermal properties may not have been measured.…”

Section: Introductionmentioning

confidence: 99%

“…Historically, HoVs have been derived indirectly from other measured physical properties (i.e., boiling points or vapor pressures) using the Clausius–Clapeyron equation. − For example, Zhou et al used a vacuum thermogravimetric analyzer (VTGA) to determine the HoVs for various renewable fuels from their VTGA-measured boiling points . Researchers have also correlated retention times in gas chromatography to inverse vapor pressure measurements, which they then translated into HoV of components.…”

Section: Introductionmentioning

confidence: 99%

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Determining the Thermal Properties of Military Jet Fuel JP-5 and Surrogate Mixtures Using Differential Scanning Calorimetry/Thermogravimetric Analysis and Differential Scanning Calorimetry Methods

Prak

Foley²,

Dorn

et al. 2020

Energy Fuels

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Heat capacity and heat of vaporization (HoV) are thermal properties that affect the combustion of fuels in engines. This study highlights new calorimetric methods to measure the thermal properties of JP-5 and surrogate fuel systems. First, the heat capacities of military jet fuel (JP-5) and surrogate fuel mixtures were measured using a stand-alone differential scanning calorimeter. The surrogates consisted of two-component and four-component mixtures, which have been reported in past studies. Six quaternary and four binary mixtures had heat capacities matching those of JP-5 at 20 °C, 1.91 ± 0.03 J•g −1 °C, within a 90% confidence interval. The heats (energy) needed to evaporate JP-5 and each surrogate mixture were determined using a differential scanning calorimetry− thermogravimetric analysis system. Isothermal measurements were used to measure pure components. A temperature ramping protocol was designed for JP-5 and surrogate mixtures. The HoV of JP-5 was determined to be 239 ± 8 J•g −1 , which falls within the range of literature values based on predictive correlations. The HoVs for six of the surrogate mixtures matched those of JP-5 within their 90% confidence intervals.

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Fuel Heat of Vaporization Values Measured with Vacuum Thermogravimetric Analysis Method

Cited by 8 publications

References 11 publications

Alcohol fuels for spark-ignition engines: Performance, efficiency and emission effects at mid to high blend rates for binary mixtures and pure components

Alcohol fuels for spark-ignition engines: Performance, efficiency and emission effects at mid to high blend rates for binary mixtures and pure components

Vacuum versus ambient pressure inert gas thermogravimetry: a study of silver carboxylates

Determining the Thermal Properties of Military Jet Fuel JP-5 and Surrogate Mixtures Using Differential Scanning Calorimetry/Thermogravimetric Analysis and Differential Scanning Calorimetry Methods

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