Fuel Evaporation in an Atmospheric Premixed Burner: Sensitivity Analysis and Spray Vaporization

Abstract

Calculation of evaporation requires accurate thermophysical properties of the liquid. Such data are well-known for conventional fossil fuels. In contrast, e.g., thermal conductivity or dynamic viscosity of the fuel vapor are rarely available for modern liquid fuels. To overcome this problem, molecular models can be used. Currently, the measurement-based properties of n-heptane and diesel oil are compared with estimated values, using the state-of-the-art molecular models to derive the temperature-dependent material properties. Then their effect on droplet evaporation was evaluated. The critical parameters were liquid density, latent heat of vaporization, boiling temperature, and vapor thermal conductivity where the estimation affected the evaporation time notably. Besides a general sensitivity analysis, evaporation modeling in a practical burner ended up with similar results. By calculating droplet motion, the evaporation number, the evaporation-to-residence time ratio can be derived. An empirical cumulative distribution function is used for the spray of the analyzed burner to evaluate evaporation in the mixing tube. Evaporation number did not exceed 0.4, meaning a full evaporation prior to reaching the burner lip in all cases. As droplet inertia depends upon its size, the residence time has a minimum value due to the phenomenon of overshooting.

Sound Pressure Level Analysis of a Liquid-Fueled Lean Premixed Swirl Burner with Various Quarls

“…The mentioned flame shapes are presented in Figure 3. Even though there are visible flares, the majority of the droplets evaporate inside the mixing tube, according to our previous work [43]. Notable flares were only observed in the λ < 1 range.…”

“…A significant portion of the ORZ is occupied and hence substituted by the 45 • quarl on the right image. inside the mixing tube, according to our previous work [43]. Notable flares were only observed in the λ < 1 range.…”

“…Over the course of the measurements, the combustion air flow rate increased from 11.9 kg/h until blowout in 2.38 kg/h steps in all setups, which meant 2 m 3 /h steps in rotameter reading. Since the atomizing air flow rate can be calculated using an adiabatic expansion at the atomizer nozzle [43], the second rotameter was used only for validation. The air-to-fuel equivalence ratio, λ, was varied in the range of 0.7-2.…”

Assessment of radiative heat transfer impact on a temperature distribution inside a real industrial swirled furnace

“…In SCM fluid flow is calculated only for one gaseous phase, which results that the evaporation process of inlet fuel is modelled inside the evaporation and induction time in Equation 3. Further description about evaporation time calculation can be found in literature [27]. This model gives good coverage of kinetic combustion for the lean region and for the burning of evaporated fuel in the region of disintegrated droplets.…”

Wavelet analysis of flame blowout of a liquid-fueled swirl burner with quarls

“…Table 1 summarizes the relevant parameters of the atomization process. The evaporation of liquid drops inside the mixing tube was calculated elsewhere 34,35 . Note that small droplets are slightly affected by both convection and radiation due to their low inertia and surface area, respectively 36 .…”