Validation of the Local Thermal Equilibrium Assumption in Forced Convection of Non-Newtonian Fluids through Porous Channels

Khashan, Saud; Al‐Nimr, M. A.

doi:10.1007/s11242-004-8305-8

Cited by 29 publications

(13 citation statements)

References 17 publications

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“…The heavy oil can be regarded as incompressible fluid and laminar flow in the capillary (Khashan and Al-Nimr, 2005;Alkam et al, 1998); and the tip effect and inertia force could be neglected for the long pipe and stable flow. Therefore, the viscous force equals the pressure differential from the inlet to the outlet.…”

Section: Test Of Heavy Oil Flowing Through Capillarymentioning

confidence: 99%

Flow Characteristics of Heavy Oil through Porous Media

Liu

Wang

Xie

et al. 2011

Energy Sources, Part A: Recovery, Utilization, and Environmenta

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Performance of flowing through a capillary and porous media for different kinds of heavy oil at different temperatures have been studied by experiments in this article. It shows that the heavy oil containing asphaltene-colloids displays yield-stress rheology (Bingham fluids). The displacing pressure difference increases linearly with the increase of the flow rate. However, the start flowing pressure is different for different heavy oil samples at different temperatures. The higher the temperature is, the lower pressure the heavy oil needs to flow; and when the temperature is high enough, the start flowing pressure equals zero. The minimum temperature at which the start flowing pressure equals zero is called converting temperature. Also, the more viscous the heavy oil is, the higher the converting temperature will be. An exponential relationship of yield stress and temperatures has been obtained for different kinds of heavy oils by the experiments of heavy oil flowing through a capillary. A logarithmic relationship of converting temperatures and the dead oil mobility at 50 ı C has been obtained for heavy oil through different porous media. When a temperature is lower than the converting temperature, the start flowing pressure gradient decreases as a log tendency with the increase of temperature when different heavy oils are flowing through different porous media. For the existence of the start flowing pressure gradient, the heavy oil production rate is different from that for the Newton fluid and it is adverse to the development of heavy oil reservoirs. The test results are favorable to choose the reasonable temperature for heavy oil transportation running in a pipe or well bore and also determine the temperature limitation for different production rates for a specific well sample. It is also important for improving the development effect efficiently.

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Section: Test Of Heavy Oil Flowing Through Capillarymentioning

confidence: 99%

Flow Characteristics of Heavy Oil through Porous Media

Liu

Wang

Xie

et al. 2011

Energy Sources, Part A: Recovery, Utilization, and Environmenta

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show abstract

“…The LTE assumption allows for merging of the two separate energy equations describing temperature in the fluid and solid phases into one, simplifying the modeling procedure by volumetric averaging (Whitaker, 1991). Previous work about the validity of the LTE assumption in porous media focused on engineering applications such as packed bed reactors (Al-Nimr & Abu-Hijleh, 2002;Al-Sumaily et al, 2013;Amiri & Vafai, 1998;Khashan & Al-Nimr, 2005). While several criteria exist to examine the appropriateness of the LTE assumption for such applications (Amiri & Vafai, 1998;Hamidi et al, 2019;Kim & Jang, 2002;Minkowycz et al, 1999;Zanoni et al, 2017;Zhang et al, 2009), a thorough investigation of the conditions under which LTE is valid for flow in porous aquifers is currently lacking.…”

Section: Introductionmentioning

confidence: 99%

On the Limitations and Implications of Modeling Heat Transport in Porous Aquifers by Assuming Local Thermal Equilibrium

Gossler

Bayer

Rau

et al. 2020

Water Resources Research

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Heat transport in natural porous media, such as aquifers or streambeds, is generally modeled assuming local thermal equilibrium (LTE) between the fluid and solid phases. Yet, the mathematical and hydrogeological conditions and implications of this simplification have not been fully established for natural porous media. To quantify the occurrence and effects of local thermal disequilibrium during heat transport, we systematically compared thermal breakthrough curves from a LTE with those calculated using a local thermal nonequilibrium (LTNE) model, explicitly allowing for different temperatures in the fluid and solid phases. For the LTNE model, we developed a new correlation for the heat transfer coefficient representative of the conditions in natural porous aquifers using six published experimental results. By conducting an extensive parameter study (>50,000 simulations), we show that LTNE effects do not occur for grain sizes smaller than 7 mm or for groundwater flow velocities that are slower than 1.6 m day −1. The limits of LTE are likely exceeded in gravel aquifers or in the vicinity of pumped bores. For such aquifers, the use of a LTE model can lead to an underestimation of the effective thermal dispersion by a factor of up to 30 or higher, while the advective thermal velocity remains unaffected for most conditions. Based on a regression analysis of the simulation results, we provide a criterion which can be used to determine if LTNE effects are expected for particular conditions.

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“…However, high Biot number, thermal conductivities ratio and porosity have a positive impact to satisfy the LTE assumption. Khashan and AL-Nimr (2005) have performed a numerical study to examine the validity of the local thermal equilibrium LTE assumption for forced convective heat transfer of non-Newtonian fluids in a channel confined by two horizontal wall planes. The results obtained over broad ranges of representative dimensionless parameters are used to map conditions at which the local thermal equilibrium assumption can or cannot be employed.…”

Section: Introductionmentioning

confidence: 99%

Comparison between Two Local Thermal Non Equilibrium Criteria in Forced Convection through a Porous Channel

Abdedou

Bouhadef

2015

JAFM

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Two criteria are used and compared to investigate the local thermal equilibrium assumption in a forced convection through a porous channel. The first criterion is based on the maximum local temperature difference between the solid and fluid phases, while the second is based on the average of the local differences between the temperature of the solid phase and the fluid phase. For this purpose, the momentum and energy equations based on the DarcyBrinkman-Forchheimer and the local thermal non equilibrium models are solved numerically using the finite volume method. The analysis focused on searching thermophysical parameters ranges which validate local thermal equilibrium hypothesis. Thus, by using the two criteria, the obtained results mainly revealed that this local thermal equilibrium assumption is verified for low thermal conductivity ratio and Reynolds number values and for high interstitial Biot number and porosity, while it is unfavorably affected by the high values of Prandtl number. However, it is also found that the parameters ranges corresponding to the local equilibrium validity depends on the selected local thermal non equilibrium criterion.

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Validation of the Local Thermal Equilibrium Assumption in Forced Convection of Non-Newtonian Fluids through Porous Channels

Cited by 29 publications

References 17 publications

Flow Characteristics of Heavy Oil through Porous Media

Flow Characteristics of Heavy Oil through Porous Media

On the Limitations and Implications of Modeling Heat Transport in Porous Aquifers by Assuming Local Thermal Equilibrium

Comparison between Two Local Thermal Non Equilibrium Criteria in Forced Convection through a Porous Channel

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