Predictive model fuel evaporation

The ORVR system is an important subsystem which reduces the contamination of evaporative fuel gas at gas station during the fueling. In this paper, a simulation model of adsoiption and desorption of evaporative fuel gas in canister of ORVR system is developed. From the comparison between the simulations and experiments, the validity of the developed model is verified and the dynamics can be predicted. This PDE model can be used to design the canister of ORVR system effectively for diverse climate and operating conditions. 

The deterministic approach of direct numerical simulation (DNS) and the probabilistic approach of probability density function (PDF) modeling are implemented for prediction of droplet dispersion and polydis-persity in liquid-fuel combustors. For DNS, a multidomain spectral element method was used for the carrier phase while tracking the droplets individually in a Lagrangian frame. The geometry considered here is a backward-facing step flow with and without a countercurrent shear. In PDF modeling, the extension of previous work to the case of evaporating droplets is discussed. 

For effective use of the developed model, information on the induction time and droplet evaporation rates, as a function of the local conditions in the shock-heated mixture, is needed. Currently, in the absence of such information, parametric studies with various constant induction times and droplet evaporation rates have been carried out. The predicted detonation velocity as a function of the initial droplet size is shown in Fig. 11.6 for a nominalJP-lO-oxygen mixture with an equivalence ratio of 0.12. A d -law evaporation with a rate of 0.1 cm /s and an induction time for the fuel-vapor of 1 //s was used for this series of simulations. The velocity deficit observed previously in many experimental studies of multiphase detonations is predicted by the numerical model. In the absence... 

The models and material property data for predicting fission metal release from fuel particles and fuel elements are described in Ref. 4. The transport of fission metals through the kernel, coatings, fuel rod matrix, and fuel element graphite is modeled as a transient diffusion process in the TRAFIC code (Section 4.2.5,2.2.1.2). The sorption isotherms which are used in the calculation of the rate of evaporation of volatile metals from graphite surfaces account for an increase in graphite sorptivity with increasing neutron fluence. 

This section presented a three-dimensional, two-phase model of the cathode and anode of a PEM Fuel Cell. The mathematical model accounts for the liquid water flux inside the gas diffusion layers by viscous and capillaiy forces and hence is capable of predicting the amount of liquid water inside the gas diffusion layers. The physics of phase change are included in this model by prescribing the local evaporation term as a function of the amount of liquid water present and the level of undersaturation, whereas the condensation has been simplified to be a function of the level of oversaturation only. 

The second method involves a predictive method that determines VLE and liquid-liquid equihbrium (LLE), which are important for designing evaporators and condensers. Another method is a powerful tool for parameter determination and optimization by Levenberg and Marquardt [28]. This method can be used to develop complex models for process engineering purposes which require an adaptation of parameters to experimental results. The final analysis method deals with the pinch-point method developed by Linnhoff etal. [29]. This technique aims to identify the maximum possible heat recovery and the minimum energy requirement of a thermal or chemical process [30-32]. The apphcation of this method to fuel cell systems is explained in the final part of this section. 

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