Assessment of simulation predictions of hydrocarbon pool fire tests.

Abstract

An uncertainty quantification (UQ) analysis is performed on the fuel regression rate model within SIERRA/Fuego by comparing to a series of hydrocarbon tests performed in the Thermal Test Complex. The fuels used for comparison for the fuel regression rate model include methanol, ethanol, JP8, and heptane. The recently implemented flamelet combustion model is also assessed with a limited comparison to data involving measurements of temperature and relative mole fractions within a 2m diameter methanol pool fire. The comparison of the current fuel regression rate model to data without UQ indicates that the model over predicts the fuel regression rate by 65% for methanol, 63% for ethanol, 95% for JP8, and 15% for heptane. If a UQ analysis is performed incorporating a range of values for transmittance, reflectance, and heat flux at the surface the current model predicts fuel regression rates within 50% of measured values. An alternative model which uses specific heats at inlet and boiling temperatures respectively and does not approximate the sensible heat is also compared to data. The alternative model with UQ significantly improves the comparison to within 25% for all fuels except heptane. Even though the proposed alternative model provides better agreement to data, particularly for JP8 and ethanol (within 15%), there are still outstanding issues regarding significant uncertainties which include heat flux gauge measurement and placement, boiling at the fuel surface, large scale convective motion within the liquid, and semi-transparent behavior.

Communication: Superstabilization of fluids in nanocontainers

“…The first order curvature correction to surface tension did not affect the validity of Eqs. (8) and (9). Higher order curvature corrections may play a more significant role for small drops/bubbles and near the spinodals.…”

“…3,6 In industry, much attention has been given to explosive boiling and rapid phase transitions, where metastable liquids such as liquefied nitrogen or natural gas vaporize violently. 9 In a broader context, proper predictions of nucleation rates rely on a precise knowledge of the properties of the metastable phase. A striking example occurs even for the simple case of condensation of Argon, where the predictions of CNT deviate more than 20 orders of magnitude from experiments.…”

Biofuel as an alternative shipping fuel: technological, environmental and economic assessment

“…The cost of the feedstock accounts for up to 75% of the total cost of biodiesel production. [41][42][43][44][45][46][47][48][49][50] Therefore, obtaining an inexpensive, reliable and stable supply of biomass is the critical issue for a successful business operation. If the cost of the feedstock is too high, the price of the final product is not competitive.…”

“…44 While large-scale liquefaction of natural gas is an established technology, small-scale liquefaction of bio-methane is a recent concept and as such, cost reduction and efficiency improvements will occur over time. [44][45][46][47][48][49][50] In the overall, the government need to play an important role in reducing alternative fuel production costs by introducing several incentive schemes, such as tax relief, financial subsidies and low fuel tariffs associated with biofuel. Biofuel production industries indirectly play a significant role in the country's economy by giving employment opportunities for the rural population, increasing income tax revenues, investing in plants and equipment.…”

“…45 More than 90% reduction of the methane slip may be possible with an oxidation catalyst, but this have so far not been tested. [45][46][47][48][49][50] This illustrates that optimising and managing the whole bio-methane production process including effective digestate storage and use is required in order to generate maximum economic value and minimum environmental impact.…”