Studies of heat transfer and water migration in soils. Final report

Walker, Wynn R.; Sabey, J. D.; Hampton, Delon

doi:10.2172/6149346

Cited by 26 publications

(3 citation statements)

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“…The combination of the Richards equation and conduction-convection heat equation as the governing model represents the water and heat transfer in soil. Such a model formulation does not include temperature gradient as a factor in the flux vapor transfer and associated sensible and latent heat fluxes; it may produce undesirable results in unsaturated soils [39]. Another limitation of Richard's equation in hygrothermal modeling is that it does not include the vapor phase of liquid.…”

Section: A Brief History Of Hygrothermal Modelsmentioning

confidence: 99%

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Exploring Historical Perspectives in Building Hygrothermal Models: A Comprehensive Review

Jalili,

Ouahbi,

Eid

et al. 2024

Buildings

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The necessity of understanding and simulating hydrological phenomena as well as their interactions and the effect of anthropogenic and climate conditions on the ecosystem have encouraged researchers for years to investigate the moisture transfer in soil. Considering the moisture transfer as an isothermal phenomenon might cause a wrong estimation due to the non-isothermal nature of the moisture movement in porous media. Hygrothermal (coupled heat and moisture transfer) models are quite diverse and are the engine of the various hygrothermal software tools used to analyze the heat and moisture in building envelopes, drying technologies, and many other applications. This paper is a literature survey conducted to provide an overview on the classical hygrothermal models to address the historical perspectives on these models. First, it investigated, from a historical point of view, the challenges behind the development of hygrothermal models as unsaturated flow theories, beginning with Buckingham theory. The non-isothermal nature of moisture was the starting point for researchers to deal with new challenges during mathematical modeling and experimental analysis. In general, the theory of coupled heat and moisture transfer first developed by J.R. Philip and De Vries and the authors in the mid-1950s inspired the novel hygrothermal models, including Sophocleous and Milly’s model, Rode’s model, Künzel’s model, and Grunewal’s model. In a parallel of hygrothermal model developments, the models of Whitaker and Luikov can also be classified as hygrothermal models; they were mostly applied in modeling the phenomenon of drying. The study highlights the application of hygrothermal models in building physics and gathered a summary of international efforts such as Annex 24, Annex 41, and the HAMSTAD project and advancements performed from the classical dew point or steady-state Glaser method. Moreover, this study emphasizes the advantages of the standard of EN 15026 and limitations of the Glaser method. To sum up, hygrothermal models are still under development based on various assumptions of moisture driving potentials and transfer coefficients.

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Section: A Brief History Of Hygrothermal Modelsmentioning

confidence: 99%

“…latent heat fluxes; it may produce undesirable results in unsaturated soils [39]. Another limitation of Richard's equation in hygrothermal modeling is that it does not include the vapor phase of liquid.…”

Section: A Brief History Of Hygrothermal Modelsmentioning

confidence: 99%

Exploring Historical Perspectives in Building Hygrothermal Models: A Comprehensive Review

Jalili,

Ouahbi,

Eid

et al. 2024

Buildings

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“…Equation Description Temperature dependence of gas diffusion coefficients (Vargaftik, 1975;Walker et al, 1981)…”

Section: Eqn Nomentioning

confidence: 99%

Design of gas collection systems: Issues and challenges

Parameswaran

Babu

2022

Waste Manag Res

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The design of a gas collection system (GCS) for a landfill involves estimating several critical parameters, such as the radius of influence (ROI), suction pressures, number of wells and their spacing. One of the biggest challenges lies in the estimation of ROI for a particular landfill. In this study, the ROI for a Bagalur landfill is estimated for various possible gas generation rates. ROI for active and passive GCS is estimated with numerical modelling (two-dimensional) for all definitions of ROI at different suction pressures. An inverse correlation was observed between the values of various definitions of ROI at different gas generation rates. Justification for this behaviour is brought out by addressing the conceptual difference between these definitions. The number of wells along with their spacing was then calculated, and the efficiency of the design was assessed with three-dimensional modelling. Passive and active systems had average methane recovery rates of 84% and 88%, respectively, with an atmospheric methane flux ranging from 10−9 to 10−10 kg m−2 s−1. The high recovery rate and low methane flux indicate the effectiveness of the design. The values of the methane flow rate from the extraction well were validated with a theoretical method, suggesting the usability of the model for future investigations.

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A Series-Parallel Model for Estimating the Thermal Conductivity of Unsaturated Soils

Tarnawski¹,

Leong

2012

Int J Thermophys

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Studies of heat transfer and water migration in soils. Final report

Cited by 26 publications

References 0 publications

Exploring Historical Perspectives in Building Hygrothermal Models: A Comprehensive Review

Exploring Historical Perspectives in Building Hygrothermal Models: A Comprehensive Review

Design of gas collection systems: Issues and challenges

A Series-Parallel Model for Estimating the Thermal Conductivity of Unsaturated Soils

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