Felipe Roman Centeno

Effect of tank diameter on thermal behavior of gasoline and diesel storage tanks fires

Studies on fire behavior are extremely important as they contribute in a firefighting situation or even to avoid such hazard. Experimental studies of fire in real scale are unfeasible, implying that reduced-scale experiments must be performed, and results extrapolated to the range of interest. This research aims to experimentally study the fire behavior in tanks of 0.04m, 0.20m, 0.40m, 0.80m and 4.28m diameter, burning regular gasoline or diesel oil S-500. The following parameters were here obtained: burning rates, burning velocities, heat release rates, flame heights, and temperature distributions adjacent to the tank. Such parameters were obtained for each tank diameter with the purpose of correlating the results and understanding the relationship of each parameter for the different geometrical scale of the tanks. Asymptotic results for larger tanks were found as (regular gasoline and diesel oil S-500, respectively): burning rates 0.050kg/(m2s) and 0.031kg/(m2s), burning velocities 4.0mm/min and 2.5mm/min, heat release rates per unit area 2200kW/m2 and 1500kW/m2, normalized averaged flame heights (Hi/D, where Hi is the average flame height, D is the tank diameter) 0.9 and 0.8. Maximum temperatures for gasoline pools were higher than for diesel oil pools, and temperature gradients close to the tanks were also higher for the former fuel. The behavior of the maximum temperature was correlated as a function of the tank diameter, the heat release rate of each fuel and the dimensionless distance from the tank.

Assessment of combustion models for numerical simulations of a turbulent non-premixed natural gas flame inside a cylindrical chamber

ABSTRACT This work presents a Computational Fluid Dynamics (CFD) study of the non-premixed combustion of natural gas with air in an axisymmetric cylindrical chamber, focusing on the contribution of the chemical reaction modeling on the temperature and the chemical species concentration fields. Simulations are based on the solution of mass, momentum, energy and chemical species conservation equations. Thermal radiation heat transfer in the combustion chamber is computed through the Discrete Transfer Radiation Method, and the Weighted-Sum-of-Gray-Gases model solves the dependence of gas absorption coefficient on the wavelength. Turbulence is modeled by the standard k-ε model. Regarding the combustion modeling, it is performed a comparison of solutions obtained with the combined Eddy Break-Up/Arrhenius (EBU/Arrhenius) and the Steady Laminar Diffusion Flamelet (SLDF) models. The finite volume method is employed to treat the differential equations. Among other results, the solution of the governing equations allows for the determination of the region where combustion takes place, the distribution of the chemical species and the velocity fields. The numerical results are compared to experimental measurements, showing varied agreements. Results indicate that, in this case, the EBU/Arrhenius model can predict the flame temperature and the concentration of the most important species with better accuracy than the more sophisticated SLDF model.

Numerical Simulation of Fire in a Gasoline Storage Tank in Reduced-Scale

With the increasing demand for energy and fuels in Brazil, the storage of liquid fuels in multiple tanks is becoming much more usual, posing challenges from the point of view of fire safety. To study this type of phenomenon and to evaluate its possible causes, detecting failures such as ones in design and erection of storage systems or in detection and protection equipment, numerical simulations are performed based on real data. This work presents numerical simulations of a small-scale tank for gasoline storage, based on an experimental study reported in literature. The present research shows results related to temperature in the region adjacent to the tank on fire, fuel mass burning rate, heat release rate and average flame height. Comparisons are made between numerical and experimental results, as well as with available literature results for similar conditions. In addition to gasoline type C (which has anhydrous ethanol in its composition), also gasoline type A (anhydrous ethanol free) is considered. The results obtained for simulations with gasoline type A presented better agreement with literature data than those for gasoline type C, the differences being due to the variable composition of the type C fuel. For example, the reported fuel mass burning rate for gasoline in literature is 0.045 kg/(m2∙s), while the present simulations provided values of 0.038 kg/(m2∙s) for type C and 0.047 kg/(m2∙s) for type A.

A Novel WSGG Model Based on Weighted Absorption-Emission Coefficients

The absorption coefficient of participating species, such as CO2 and H2O, shows very irregular dependence with the wavenumber, which makes it difficult the spectral integration of the radiative transfer equation (RTE). This task can be performed with the line-by-line (LBL) integration, which is very computationally expensive due to the vast amount of spectral lines that span the spectrum. As alternatives to the LBL integration, there are global models, such as the weighted-sum-of-gray-gases (WSGG) and the spectral line weighted-sum-of-gray gases (SLW). These models replace the integration with respect to the wavenumber by the summation over a certain number of gray gases, thus reducing the computational effort. This paper shows a modification of the WSGG model, in which the absorption and emission coefficients of each gray gas are considered to be function of the temperature. The model, named WSGG with non-constant coefficients (NCC-WSGG), is applied to solve a few non-isothermal and non-homogeneous problems. The results show very satisfactory agreement with the LBL integration.Copyright