Experimental investigation of the thermal dispersion coefficient under forced groundwater flow for designing an optimal groundwater heat pump (GWHP) system

Park, Byeong-Hak; Lee, Bo Hyun; Lee, Kang‐Kun

doi:10.1016/j.jhydrol.2018.05.023

Cited by 22 publications

(9 citation statements)

References 45 publications

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“…With a steady increase of such systems leading to densely used aquifers (Pophillat et al, 2020), there is a growing need for reliable prediction of the induced thermal plumes (Böttcher et al, 2019; Epting et al, 2017; Ferguson, 2009; Hähnlein et al, 2013; Herbert et al, 2013). To delineate a thermal range or a thermally affected zone in an aquifer, the value for thermal dispersion is of crucial importance (Molina‐Giraldo et al, 2011; Park et al, 2015, 2018; Pophillat et al, 2020). Consequently, the processes that determine its magnitude must be well understood.…”

Section: Resultsmentioning

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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Section: Resultsmentioning

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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“…In the analysis, the quality of fit was assessed by the root mean square error (RMSE) value Equation 3, and thermal properties were determined from the best-fitted model minimizing the RMSE value. More details on the parameter estimation procedure can be found in the recent literature (Park et al, 2018). To quantify a transport regime, the thermal peclet number, characterizing the relative contribution of convective and conductive heat transport, was defined as in Equation 4 (de Marsily, 1986;Anderson, 2005;Rau et al, 2014).…”

Section: Methodsmentioning

confidence: 99%

Impacts of injection temperature on the relevant heat transport processes in groundwater heat pump (GWHP) systems

Park¹,

Lee²

2018

Proceedings of the IGSHPA Research Track 2018

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In many hydrogeological applications, the influence of temperature on fluid density and viscosity have often been neglected. However, high contrasts in temperature which occurs in the field applications such as groundwater heat pump (GWHP) systems, can make the effects of variable density and viscosity on flow and transport significant. A theoretical study suggests that free convection occurs in an infinitely extensive horizontal layer when the Rayleigh number exceeds about 40. Experimental investigations are still lacking on the conditions where the influence of temperature can be important. In this study, a laboratory experimental system was developed to investigate the impacts of injection temperature on the relevant heat transport processes. First of all, the experiments such as sieve analysis and constant-head permeability test were performed to estimate the physical properties of the saturated porous medium. Laboratory tracer tests using a resistor as a heat source were conducted with/without background flow conditions to derive the thermal properties of the medium. Lastly, tracer tests using injected water with different temperatures were performed to identify the certain conditions where the variations in fluid density and viscosity play an important role in the subsurface flow and transport.

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“…바닥재는 보수력(water holding capacity) 및 통기성이 높아, 펄라이트 및 질석을 대체하는 상토성 분으로 활용할 수 있다 (Park and Kim, 2012). 비산재는 콘크리트 혼화재, 시멘트 원료 등 자원화 하기 위한 개 발이 국내외적으로 적극적으로 추진되고 있으며 (Oh, 2006;Zacco et al, 2014;Behnood et al, 2015;Lee et al, 2017), (NIER, 2011;Park and Kim, 2012;Maeng et al, 2014) (Park et al, 2018). 주문진사의 균등 계수는 1.36으로 매우 분급이 잘되어 균질하며, 평균 입도는 2 mm 로 거친 모래(coarse sand)로 분류된다 (Friedman and Sanders, 1978).…”

Section: 요 약unclassified

A Study on Infiltration Process and Physicochemical Influence in the Unsaturated and the Saturated Zone of the Bottom Ashes from Thermal Power Plant

Park

Joun

et al. 2022

Econ. Environ. Geol.

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This study focused on the physicochemical effects of bottom ash dissolved precipitation on the soil and groundwater environment. The iced column and percolation experiments showed that most of the bottom ash particles were drained as the ash-dissolved solution, while the charcoal powder was filtered through the soil. Ion species of Al, As, Cu, Cd, Cr, Pb, Fe, Mn, Ca, K, Si, F, NO 3 , SO 4 were analyzed from the eluates collected during the 24 h column test. In the charcoal powder eluates, a high concentration of K was detected at the beginning of the reaction, but it decreased with time. The concentrations of Al and Ca were observed to increase with time, although they existed in trace amount. In the bottom ash eluates, the concentrations of Ca and SO 4 decreased by 30 mg•L -1 and 67 mg•L -1 , respectively, over 24 h. It is regarded that the infiltration patterns of the bottom ash and biochar in the unsaturated zone were different owing to their particle sizes and solvent properties. It is expected that a significant amount of the bottom ash will mix with the precipitation and percolate below the water table, especially in the case of thin and highly permeable unsaturated zone. The biochar was filtered through the unsaturated zone. The biochar did not dissolve in the groundwater, although it reached the saturation zone. For these reasons, it is considered that the direct contamination by the bottom ash and biochar are unlikely to occur.

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Experimental investigation of the thermal dispersion coefficient under forced groundwater flow for designing an optimal groundwater heat pump (GWHP) system

Cited by 22 publications

References 45 publications

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

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

Impacts of injection temperature on the relevant heat transport processes in groundwater heat pump (GWHP) systems

A Study on Infiltration Process and Physicochemical Influence in the Unsaturated and the Saturated Zone of the Bottom Ashes from Thermal Power Plant

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