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Type: Artigo de periódico
Title: Nonequilibrium modeling of an ammonia-water rectifyng column via fundamental thermodynamic and transport relations
Author: Figueiredo, J. R.
Fernandes, B. L.
Silverio, R. J. R.
Abstract: A nonequilibrium heat and mass transfer model is presented for the steady-state operation of a rectifying column, employed in ammonia-water absorption refrigeration systems to dehumidify the ammonia vapor leaving the generator. The thermodynamic state relations of the mixture are derived from two equations representing the Gibbs free energy in terms of temperature, pressure and concentration for the liquid and the vapor phases. Two of the transport properties, surface tension and liquid diffusivity required original relations, as presented here in. The resulting nonlinear system of equations is solved by efficient use of the Newton-Raphson code that minimizes the order of the Jacobian matrix without losing any model information or the quadratic order of convergence of the numerical method. Accuracy tests are performed by grid refinement and by comparison with results in the literature. A sensitivity study is presented showing the influence of some alternative methods for estimation of the transport properties on the temperature and concentration profiles.
Subject: Rectifier
Absorption refrigeration
Heat and mass transfer
Non-equilibrium model
Editor: Brazilian Society of Chemical Engineering
Rights: aberto
Identifier DOI: 10.1590/S0104-66322006000400012
Date Issue: 1-Dec-2006
Appears in Collections:Artigos e Materiais de Revistas Científicas - Unicamp

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