Moisture Transport in Silica Gel Particle Beds: I. Theoretical Study

Pesaran, A.; Mills, A. F.

doi:10.2172/914653

Cited by 16 publications

(40 citation statements)

References 5 publications

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“…Appropriate ϕ v -weighted functions were developed that take into account the individual dry-air and water-vapour properties available from thermodynamic tables [59]. The properties of the desiccant medium are referred to silica gel RD [6].…”

Section: Resultsmentioning

confidence: 99%

“…Dropping equation (1), the local value of the vapour mass fraction ϕ v is specified as the equilibrium value ϕ v,eq , obtained from the sorption isotherm as a function of the local values of T and X [6]. Consequently, the source-term S vrepresenting the adsorption rate per unit volume of the porous medium is expressed by:…”

Section: Model Equations Coefficients and Propertiesmentioning

confidence: 99%

“…The specific enthalpy of the water vapour is given by (6) and that of the adsorbed water is given by…”

Section: Model Equations Coefficients and Propertiesmentioning

confidence: 99%

“…The effective diffusivity associated with Knudsen diffusion in a porous desiccant medium may be written as [6]:…”

Section: Model Equations Coefficients and Propertiesmentioning

confidence: 99%

“…The study of the transport phenomena in desiccant airflow systems has been addressed in numerous research works, many of them concerning combined desiccant cooling and dehumidification, air filtering, air dehumidification and energy recovery processes (e.g., [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]). …”

Section: Introductionmentioning

confidence: 99%

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On the validity of lumped capacitance approaches for the numerical prediction of heat and mass transfer in desiccant airflow systems

Ruivo

Costa

Figueiredo

2008

International Journal of Thermal Sciences

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In the present work, a detailed model of simultaneous heat and mass transfer through a desiccant micro-porous medium of a channel wall of compact heat and mass exchangers, such as desiccant wheels, was developed. The relevant phenomena considered by this model within the porous medium are surface diffusion of the adsorbed water, Knudsen diffusion of water vapour, heat conduction and the sorption process. A onedimensional formulation of this model is used to investigate the validity of two simplifying approaches based on the lumped-capacitance method. One consists of neglecting the transversal heat and mass transfer resistances within the porous medium, the other of cancelling only the thermal resistance.Results are presented for a wide range of values of the layer thickness of the porous medium. It is concluded that the hypothesis of nullresistances in the cross direction is valid only for layer thicknesses lower than 0.1 mm, approximately, while the approach based on the thermal lumped capacitance model is valid for layer thicknesses lower than 5 mm. Finally, a dimensional analysis of interfacial balances leads to the conclusion that the Biot number for surface diffusion is several orders of magnitude higher than the corresponding thermal Biot number.

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Section: Resultsmentioning

confidence: 99%

Section: Model Equations Coefficients and Propertiesmentioning

confidence: 99%

“…The specific enthalpy of the water vapour is given by (6) and that of the adsorbed water is given by…”

Section: Model Equations Coefficients and Propertiesmentioning

confidence: 99%

“…The effective diffusivity associated with Knudsen diffusion in a porous desiccant medium may be written as [6]:…”

Section: Model Equations Coefficients and Propertiesmentioning

confidence: 99%