Dynamic model evaporators

K. Patan and T. Parisini. Identification of neural dynamic models for fault detection and isolation the case of a real sugar evaporation process. Journal of Process Control, 15 67-79, 2005. 

INTRODUCTION 210 STATUS OF RESIDENTIAL MODELS 211 EXPOSURE PHASES IN RESIDENTIAL EXPOSURE 212 Mixing and Loading Phase 212 Application Phase 212 Post-Apphcation Phase 213 MODEL CONCEPTS FRAMEWORKS 214 Mass-Balanced Air Qnality Model 214 Fngacity Model 215 Flnid Dynamics Model 216 MODEL CONCEPTS SOURCES AND SINKS 216 Sonrce Evaporation of Pesticides 216 Vapor-Pressnre-Driven Evaporation 216 Chinn Evaporation 217... 

Tzivion S, Feingold G, I-evin Z (1989) The evolution of raindrop spectra. Part 11 Collisional collection/breakup and evaporation in arainshaft. J Atmos Sci 46 3312-3327 Wesely ML (1989) Parametrization of surface resistance to gaseous dry deposition in regional numerical models. Atmos Environ 16 1293-1304 Whitby ER, McMurry PH, Shankar U, Binkowski FS (1991) Modal aerosol dynamics modelling. Rep. 600/3-91A120, Atmospheric Research and Exposure Assessment Laboratory, U.S. 

Formally, the dynamic model has to be completed by adding an equation for the temperature T. However, the calculations show that the temperature relaxation time is less than that for concentration by two orders of magnitude. It permits us to exclude the equation for T from the model. The same calculation confirmed that without liquid condensation and evaporation, the reaction-rate hysteresis does not occur. Thus, the hysteresis is not attributed to the well-known multiplicity of steady-states in a gradientless reactor. 

Table 7.3 Dynamic model of a batch nylon 6,6 evaporator, accounting for cyclic oligomer and HMD loss using the functional-group modeling approach...

This work is part of the smart enterprise division in Tumut Visy Pulp and Paper, and addresses the advanced control and operation of the mill. In this context, a robust dynamic model is developed for the recovery boiler, and validated over a wide range of operating conditions. In the steady state case, energy and mass balances were carried out over the different sections of the process. In the dynamic case, initially, heat and mass transfer across the bed are coupled with moisture evaporation, black liquor pyrolysis, char combustion and gasification, gas-phase. The influence of model parameters kinetic constants and operational variables on process dynamics are studied by numerical simulation. The model was developed/implemented in a Visual C++ environment. 

The dynamic model is based on mass and energy balances for the solid phases and mass and energy balances for the gas phases which are coupled with moisture evaporation, black liquor devolatilization, char combustion and gas-phase combustion. 

The ternary model was established to investigate the effects of a solvent in polymer blends during phase separation. In cases of constant solvent concentration it emerged that, the less solvent that was in solution, the slower was the evolution of the morphology in phase separation. This effect was due to the polymers being immiscible with each other, but both being miscible with the solvent. The addition of a solvent decreased the free energy level in the blend, which in turn slowed down the evolution of phase separation. The mechanism of phase separation with solvent evaporation was further complicated by dynamic solvent evaporation from the ternary system. 

The BET treatment is based on a kinetic model of the adsorption process put forward more than sixty years ago by Langmuir, in which the surface of the solid was regarded as an array of adsorption sites. A state of dynamic equilibrium was postulated in which the rate at which molecules arriving from the gas phrase and condensing on to bare sites is equal to the rate at which molecules evaporate from occupied sites. 

Aerosol Dynamics. Inclusion of a description of aerosol dynamics within air quaUty models is of primary importance because of the health effects associated with fine particles in the atmosphere, visibiUty deterioration, and the acid deposition problem. Aerosol dynamics differ markedly from gaseous pollutant dynamics in that particles come in a continuous distribution of sizes and can coagulate, evaporate, grow in size by condensation, be formed by nucleation, or be deposited by sedimentation. Furthermore, the species mass concentration alone does not fliUy characterize the aerosol. The particle size distribution, which changes as a function of time, and size-dependent composition determine the fate of particulate air pollutants and their... 

To build a molecular model of the equilibrium between a liquid and its vapor we first suppose that the liquid is introduced into an evacuated closed container. Vapor forms as molecules leave the surface of the liquid. Most evaporation takes place from the surface of the liquid because the molecules there are least strongly bound to their neighbors and can escape more easily than those in the bulk. Howevei as the number of molecules in the vapor increases, more of them become available to strike the surface of the liquid, stick to it, and become part of the liquid again. Eventually, the number of molecules returning to the liquid each second matches the number escaping (Fig. 8.2). The vapor is now condensing as fast as the liquid is vaporizing, and so the equilibrium is dynamic in the sense introduced in Section 7.11 ... 

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. 

Payer80 states that the UNSAT-H model was developed to assess the water dynamics of arid sites and, in particular, estimate recharge fluxes for scenarios pertinent to waste disposal facilities. It addresses soil-water infiltration, redistribution, evaporation, plant transpiration, deep drainage, and soil heat flow as one-dimensional processes. The UNSAT-H model simulates water flow using the Richards equation, water vapor diffusion using Fick s law, and sensible heat flow using the Fourier equation. 

Ge and Fan (2005) developed a 3-D numerical model based on the level-set method and finite-volume technique to simulate the saturated droplet impact on a superheated flat surface. A 2-D vapor-flow model was coupled with the heat-transfer model to account for the vapor-flow dynamics caused by the Leidenfrost evaporation. The droplet is assumed to be spherical before the collision and the liquid is assumed to be incompressible. 

To test the validity of Eqs. (25) and (31), we have performed simulations of groove relaxation under evaporation-condensation dynamics and numerical integration of (31). Below we describe briefly the model simulated and present data for the averaged surface profile and the lifetime of the top terrace during relaxation. Details of this study will be reported elsewhere. 

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