Study of heat and moisture transfer in soil with a dry surface layer

Liu, B.C.; Liu, W.; Peng, S. W.

doi:10.1016/j.ijheatmasstransfer.2005.06.004

Cited by 62 publications

(24 citation statements)

References 19 publications

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“…(Rather than actually transporting the evaporated water out of the soil column, the equilibrium model "pushed" the moisture deeper into the soil ahead of the evaporative front as discussed in the Introduction.) On the other hand, despite the fact that the present estimates of evaporative loss are clearly a major improvement over the equilibrium results, both the equilibrium and nonequilibrium model solutions produce a sharply delineated advancing drying front, which is reminiscent of a Stefan-like or moving-boundary condition problem (e.g., see Whitaker and Chou, 1983, 1984, or Liu et al, 2005. So neither simulation actually captures the final observed moisture profile behind the drying front.…”

Section: Quincy Sandmentioning

confidence: 65%

A non-equilibrium model for soil heating and moisture transport during extreme surface heating: the soil (heat–moisture–vapor) HMV-Model Version 1

Massman

2015

Geosci. Model Dev.

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Abstract. Increased use of prescribed fire by land managers and the increasing likelihood of wildfires due to climate change require an improved modeling capability of extreme heating of soils during fires. This issue is addressed here by developing and testing the soil (heat-moisture-vapor) HMVmodel, a 1-D (one-dimensional) non-equilibrium (liquidvapor phase change) model of soil evaporation that simulates the coupled simultaneous transport of heat, soil moisture, and water vapor. This model is intended for use with surface forcing ranging from daily solar cycles to extreme conditions encountered during fires. It employs a linearized Crank-Nicolson scheme for the conservation equations of energy and mass and its performance is evaluated against dynamic soil temperature and moisture observations, which were obtained during laboratory experiments on soil samples exposed to surface heat fluxes ranging between 10 000 and 50 000 W m −2 . The Hertz-Knudsen equation is the basis for constructing the model's non-equilibrium evaporative source term. Some unusual aspects of the model that were found to be extremely important to the model's performance include (1) a dynamic (temperature and moisture potential dependent) condensation coefficient associated with the evaporative source term, (2) an infrared radiation component to the soil's thermal conductivity, and (3) a dynamic residual soil moisture. This last term, which is parameterized as a function of temperature and soil water potential, is incorporated into the water retention curve and hydraulic conductivity functions in order to improve the model's ability to capture the evaporative dynamics of the strongly bound soil moisture, which requires temperatures well beyond 150 • C to fully evaporate. The model also includes film flow, although this phenomenon did not contribute much to the model's overall performance. In general, the model simulates the laboratoryobserved temperature dynamics quite well, but is less precise (but still good) at capturing the moisture dynamics. The model emulates the observed increase in soil moisture ahead of the drying front and the hiatus in the soil temperature rise during the strongly evaporative stage of drying. It also captures the observed rapid evaporation of soil moisture that occurs at relatively low temperatures (50-90 • C), and can provide quite accurate predictions of the total amount of soil moisture evaporated during the laboratory experiments. The model's solution for water vapor density (and vapor pressure), which can exceed 1 standard atmosphere, cannot be experimentally verified, but they are supported by results from (earlier and very different) models developed for somewhat different purposes and for different porous media. Overall, this non-equilibrium model provides a much more physically realistic simulation over a previous equilibrium model developed for the same purpose. Current model performance strongly suggests that it is now ready for testing under field conditions.

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Section: Quincy Sandmentioning

confidence: 65%

A non-equilibrium model for soil heating and moisture transport during extreme surface heating: the soil (heat–moisture–vapor) HMV-Model Version 1

Massman

2015

Geosci. Model Dev.

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“…Remund et al [5] studied the field testing method of soil properties and discussed the influence of soil features on the scale and heat transfer capacity of underground heat exchanger, working medium temperature and system efficiency. Liu et al [6] developed a mathematical model to investigate water evaporation, transient distributions of temperature and moisture in the porous soil with a dry surface layer at environmental conditions and conducted an experiment in a closed-loop wind tunnel to investigate the temperature effect on soil moisture transport. They found that the dry surface layer had an important effect on heat and moisture migration in soil and the influence of temperature on moisture transport in unsaturated soil is significant.…”

Section: Introductionmentioning

confidence: 99%

Experimental study on heat and moisture transfer in soil during soil heat charging for solar-soil source heat pump compound system

Chen

Ding

Liu

et al. 2014

Applied Thermal Engineering

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“…In practice, the conventional evaporation models [29][30][31][32][33][34] that are used in watershed hydrology (e.g., Soil and Water Assessment Tool or SWAT) [35,36] and land-atmosphere interaction (e.g., Community Land Model or CLM) [37,38] models estimate soil water evaporation without explicitly considering the VFR effect [39,40] partially due to our insufficient knowledge of physical dynamics (e.g., thickness variation and the vaporization-condensation cycle) within DSL. Alternatively, those models simply use a lumped parameter, namely surface resistance ( [40][41][42][43][44][45][46][47][48][49][50].…”

Section: Introductionmentioning

confidence: 99%

Vapor Flow Resistance of Dry Soil Layer to Soil Water Evaporation in Arid Environment: An Overview

Wang

2015

Water

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Evaporation from bare sandy soils is the core component of the hydrologic cycle in arid environments, where vertical water movement dominates. Although extensive measurement and modeling studies have been conducted and reported in existing literature, the physics of dry soil and its function in evaporation is still a challenging topic with significant remaining issues. Thus, an overview of the previous findings will be very beneficial for identifying further research needs that aim to advance our understanding of the vapor flow resistance (VFR) effect on soil water evaporation as influenced by characteristics of the dry soil layer (DSL) and evaporation zone (EZ). In this regard, six measurement and four modeling studies were overviewed. The results of these overviewed studies, along with the others, affirm the conceptual dynamics of DSL and EZ during drying or wetting processes (but not both) within dry sandy soils. The VFR effect tends to linearly increase with DSL thickness (δ) when δ < 5 cm and is likely to increase as a logarithmic function of δ when δ ≥ 5 cm. The vaporization-condensation-movement (VCM) dynamics in a DSL depend on soil textures: sandy soils can form a thick (10 to 20 cm) DSL while sandy clay soils may or may not have a clear DSL; regardless, a DSL can function as a transient EZ, a vapor condensation zone, and/or a vapor transport medium. Based on the overview, further studies will need to generate long-term continuous field data, develop hydraulic functions for very dry soils, and establish an approach to quantify the dynamics and VFR effects of DSLs during wetting-drying cycles as well as take into account such effects when using conventional (e.g., Penman-Monteith) evaporation models. OPEN ACCESS

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Study of heat and moisture transfer in soil with a dry surface layer

Cited by 62 publications

References 19 publications

A non-equilibrium model for soil heating and moisture transport during extreme surface heating: the soil (heat–moisture–vapor) HMV-Model Version 1

A non-equilibrium model for soil heating and moisture transport during extreme surface heating: the soil (heat–moisture–vapor) HMV-Model Version 1

Experimental study on heat and moisture transfer in soil during soil heat charging for solar-soil source heat pump compound system

Vapor Flow Resistance of Dry Soil Layer to Soil Water Evaporation in Arid Environment: An Overview

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