Common tangent plane in mixed-gas adsorption

Santori, Giulio; Luberti, Mauro; Brandani, Stefano

doi:10.1016/j.fluid.2015.02.017

Cited by 7 publications

(7 citation statements)

References 17 publications

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“…Even the three-parameter ABC equation introduced by Siperstein and Myers [6] reduces to the 1-parameter Margules equation in case of isothermal conditions. Moreover, this equation has been successfully applied to the common tangent plane approach to validate the presence of adsorption azeotropes [40].…”

Section: -Parameter Margules Equationmentioning

confidence: 99%

Activity coefficient models for accurate prediction of adsorption azeotropes

et al. 2021

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In this study seven adsorption azeotropes involving binary systems and zeolite-based adsorbents were systematically investigated. Pure component isotherms and mixed-gas adsorption data were taken from published literature except for the benzene–propene system on silicalite, which is newly presented in this work using molecular simulations. Experimental adsorbed phase composition and total amount adsorbed of the azeotropic systems were compared with the predictions of several models including: the ideal adsorbed solution theory (IAST), the heterogeneous ideal adsorbed solution theory (HIAST) and the real adsorbed solution theory (RAST) coupled with the 1-parameter Margules (1-Margules) and the van Laar equations. In the latter two models an additional loading parameter was incorporated in the expression of the excess Gibbs energy to account for the reduced grand potential dependency of the activity coefficients in the adsorbed phase. It was found that the HIAST and RAST–1-Margules models were able to predict the azeotropic behaviour of some systems with good accuracy. However, only the RAST–van Laar model consistently showed an average relative deviation below 3% compared to experimental data for both the adsorbed phase composition and the total amount adsorbed across the systems. This modified van Laar equation is therefore preferable in those engineering applications when the location of adsorption azeotropes is required with great accuracy and when there is lack of detailed characterization of the adsorbent that is needed to carry out molecular simulations.

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Section: -Parameter Margules Equationmentioning

confidence: 99%

Activity coefficient models for accurate prediction of adsorption azeotropes

et al. 2021

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“…the evaporator is open and the vapor generated in the evaporator is adsorbed in the bed. The modelling of this connection can be extended from our previous works [19,20] based on ideal and non-ideal isothermal-isochoric flash for adsorption compressor considering the additional evaporator connected to the adsorption bed at equilibrium. The resulting system of equations for NC component in the adsorption bed is: To model the vapor and liquid phases, the Peng-Robinson-Stryjek-Vera (PRSV) equation of state [14] was selected with a ϕ-ϕ approach.…”

Section: (A) Adsorption Bed/evaporator Connection: In This Stage Thementioning

confidence: 99%

“…(a) Adsorption bed/Evaporator connection: In this stage, the valve between the adsorption bed and the evaporator is open and the vapor generated in the evaporator is adsorbed in the bed. The modelling of this connection can be extended from our previous works [19,20] based on ideal and non-ideal isothermal-isochoric flash for adsorption compressor considering the additional evaporator connected to the adsorption bed at equilibrium. The resulting system of equations for NC component in the adsorption bed is:…”

Section: Case Study A: Complete Cycle Modelling With Prsv + Iastmentioning

confidence: 99%

Ammonia/Ethanol Mixture for Adsorption Refrigeration

2020

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Adsorption refrigeration has become an attractive technology due to the capability to exploit low-grade thermal energy for cooling power generation and the use of environmentally friendly refrigerants. Traditionally, these systems work with pure fluids such as water, ethanol, methanol, and ammonia. Nevertheless, the operating conditions make their commercialization still unfeasible, especially owing to safety and cost issues as a consequence of the working pressures, which are higher or lower than 1 atm. The present work represents the first thermodynamic insight in the use of mixtures for adsorption refrigeration and aims to assess the performance of a binary system of ammonia and ethanol. According to the Gibbs’ phase rule, the addition of a component introduces an additional degree of freedom, which allows to adjust the pressure of the system varying the composition of the mixture. The refrigeration process was simulated with isothermal- isochoric flash calculations to solve the phase equilibria, described by the Peng-Robinson-Stryjek-Vera (PRSV) equation of state for the vapor and liquid phases and by the ideal adsorbed solution theory (IAST) and the multicomponent potential theory of adsorption (MPTA) for the adsorbed phase. In operating condenser and evaporator, pressure levels around atmospheric pressure can be achieved using an ammonia/ethanol mixture with a mole fraction of ethanol in the range of 0.70−0.75. A good agreement in the predictions of the adsorbed phase composition was also reported using the IAST and the MPTA methods.

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“…The set of equations to be solved in terms of fugacities, which can be obtained from the expressions in Santori et al (2015) assuming an ideal adsorbed solution, can be summarised as follows:…”

Section: The Ideal Adsorbed Solution Theory (Iast) Equationsmentioning

confidence: 99%