Infinite Source Research Articles

On groundwater flow and shallow geothermal potential: A surrogate model for regional scale analyses

Many cities worldwide lay upon alluvial aquifers which have a great potential for low temperature geothermal installations thanks to the thermal diffusive properties of saturated porous media and the constant temperature of the subsurface. In addition, aquifers with fast moving groundwater have a higher potential due to the additional energy replenishment by advection, which is often underestimated.This work aims at bridging the gap between quantitative hydro-thermal numerical analysis and regional scale assessment developing a process-based surrogate model for the estimation of the thermal exchange (geothermal) potential of ground source heat pumps (GSHP) considering groundwater advection. The proposed method is based on a synthetic 3D FEM model reproducing the infinite line source configuration and introducing groundwater advection. Conductive/advective g-functions were derived from the numerically simulated space-time thermal perturbation for a comprehensive set of hydrogeological regimes, and a surrogate model was developed by a machine learning (ML) regression of the thermal response of the system. This solution, beyond the run time of the numerical study and the ML training phase, is very fast, applicable at any scale and scalable to any desired depth.The trained model can be used to predict the geothermal potential of GSHP for almost all sedimentary basins around the world upon the availability of the required input data (aquifer thickness and saturation, aquifer porosity and groundwater flow velocity). In this study, large scale geothermal potential maps were generated from input layers implemented in a GIS, for a demonstrative area in northern Italy showing highly variable groundwater flow (Darcy velocity from 10−3 to 10+3 m/y). A promising increase (up to +250 %) in the thermal exchange potential of GSHP due to the contribution of advection was highlighted discussing the benefits of groundwater flow and the amount of usable potential with implications on shallow geothermal energy management and development.

Generation of Artificial ULF/ELF Electromagnetic Emission in the Ionosphere by Horizontal Ground‐Based Current System

AbstractThe feasibility of the detection of electromagnetic response in the upper ionosphere to ground large‐scale ultra‐low‐frequency (ULF) and extremely‐low‐frequency (ELF) transmitters by low‐Earth‐orbit (LEO) satellites is considered. As an example of such transmitters, we consider the ZEVS 82 Hz transmitter, FENICS installation driven by 0.5–150 Hz generator, and industrial 50 Hz unbalanced power transmission lines. We numerically model the ULF/ELF wave energy leakage into the upper ionosphere from an oscillating grounded linear power line of a finite length suspended above a ground with a finite resistivity. The numerical scheme is based on the theoretical formalism developed to describe the excitation of an electromagnetic field by a horizontal grounded dipole. A realistic altitudinal profile of the plasma parameters has been reconstructed with the use of the IRI ionospheric model. For the ZEVS transmitter powered by 200 A current the modeled amplitudes of electromagnetic response can reach in the upper nightside ionosphere up to 60 µV/m and 6 pT. The assumption of an infinite source scale overestimates the ionospheric response by a factor of ∼7 as compared with realistic scale 60 km of the ZEVS transmitter. Unbalanced 50 Hz current of 10 A in large‐scale (>100 km) power transmission lines can produce the electric response in the upper ionosphere that is sufficient to be detected by electric sensors at LEO satellite. The stimulation of artificial Pc1 pulsations (0.5 Hz) with amplitudes ∼1 pT and ∼10 µV/m by large‐scale (>100 km) power lines is possible with driving current >100 A. The use of decommissioned power lines can be a cheap and efficient tool to stimulate Pc1 pulsations in the ionosphere.

Consistency in thermal conductivity measured via lab-, field-scale test, and numerical simulation for newly developed backfill materials for underground power cable system

This study investigates the thermal properties of newly developed backfill materials (normal and prepacked concrete) for an underground power cable system (UPCS) through different methods (laboratory test, in-situ horizontal thermal response test (TRT), and numerical analysis). First, the thermal conductivities of small-scale backfill materials were measured in a laboratory using a hot disk sensor. Afterward, a 5 × 3 × 2 m full-scale backfill was prepared for the TRT. The infinite line source (ILS) model was employed to estimate the thermal conductivity of the backfill materials using data from the TRT. Finally, a numerical analysis was conducted to simulate the heat transfer process during the TRT and back-calculate the thermal conductivity of the proposed backfill materials. All tests were also conducted using conventional backfill materials, namely natural sand, for comparison with the proposed backfill materials. The results indicated that the prepacked concrete type has the highest thermal conductivity among the three backfill materials regardless of the testing method employed. In addition to a high thermal conductivity, this newly developed material also has good workability (382 mm for the grout), low bleeding, and satisfactory excavation ability for the backfill material (1.56 MPa). Furthermore, the ILS model and numerical model slightly overestimated the thermal conductivity (less than 8 %) compared to the measured values from the laboratory test involving normal and prepacked concretes; however, natural sand exhibited a significant difference (1.365 W/(mK) and 1.8 W/(mK), 32 %) owing to the influence of the water content on its thermal conductivity. In addition, thermal conductivities calculated by the ILS model and numerical simulation were in very good agreement (with the difference being lower than 3 %), demonstrating that the proposed ILS model is appropriate to use to estimate the thermal conductivity of large-scale backfill material using horizontal TRT data.

In vitro antioxidant, anti-inflammatory activities and acetylcholinesterase inhibition properties of selected plant extracts

Plant extracts remain an infinite source of bioactive chemicals and an inexhaustible resource for discovering new drugs of natural origin. Thus, in this study, we focused on analysing 29 ethanolic extracts (E1-E29) from selected plants of flora of Poland to assess their antioxidant, anti-inflammatory and acetylcholinesterase inhibitory properties in relation to the chemical profiles of phenolic compounds. The results show that the investigated samples differed in terms of their chemical compositions and biological activities. The extract from Cirsium palustre leaves (E13) possesses the highest phenolic and flavonoid contents as well as antiradical activity in the DPPH (2,2-diphenyl-1-picrylhydrazyl) test (415.28 ± 2.22 µM of Trolox equivalent). On the other hand, the most potent anti-inflammatory agents (at 125 µg/mL) were extracts from Odontites vulgaris herbs (E24), with a COX-2 (cyclooxygenase-2) inhibition percentage of 74.54 ± 0.77, and Erigeron acris flower heads (E22), with a 15-sLOX (soybean 15-lipooxygenase) inhibition percentage of 42.45 ± 3.32. All extracts exhibited moderate acetylcholinesterase inhibitory activity. Moreover, to the best of our knowledge, the present study is the first to report phytochemical and pharmacological analyses of extracts from Anthericum ramosum and Lysimachia europaea.

Reversible Na Plating/Stripping with High Areal Capacity Using an Electroconductive Liquid Electrolyte System.

Anode-free sodium-metal batteries (AFSMBs) are promising candidates for maximizing energy density and minimizing cost and safety hazards in the absence of metallic sodium during cell assembly. The practical implementation of AFSMBs is hindered by the low cycling stability of Na-metal plating and stripping, particularly under high areal capacities, due to unstable solid electrolyte interphase (SEI) layer formation with electrolyte decomposition and inactive dead Na formation. Here, we proposed an electroconductive electrolyte system consisting of liquid electrolytes that accept electrons at a certain energy level and form electronically conductive and solid electrolytes that prevent internal short circuit through low electronic conductivity. The electron acceptability and high electronic conductivity of the liquid electrolyte can suppress the irreversible electron transfer with electrolyte decomposition and reutilize the inactive dead metal, respectively. The functions of the system were demonstrated using a sodium biphenyl liquid electrolyte-NASICON solid electrolyte in a seawater battery (SWB) system, which features an infinite sodium source. The anode-free SWB cells achieved a high Coulombic efficiency of ≥99.9% for over 60 cycles at a high areal capacity of ∼24 mAh/cm2. This study provides insight into the Na plating/stripping properties in anode-free systems and proposes a significant strategy for improving the reversibility of metal anodes for various battery systems with solid electrolytes.

Periodic ethanol supply as a path toward unlimited lifespan of Caenorhabditis elegans dauer larvae.

The dauer larva is a specialized stage of worm development optimized for survival under harsh conditions that have been used as a model for stress resistance, metabolic adaptations, and longevity. Recent findings suggest that the dauer larva of Caenorhabditis elegans may utilize external ethanol as an energy source to extend their lifespan. It was shown that while ethanol may serve as an effectively infinite source of energy, some toxic compounds accumulating as byproducts of its metabolism may lead to the damage of mitochondria and thus limit the lifespan of larvae. A minimal mathematical model was proposed to explain the connection between the lifespan of a dauer larva and its ethanol metabolism. To explore theoretically if it is possible to extend even further the lifespan of dauer larvae, we incorporated two natural mechanisms describing the recovery of damaged mitochondria and elimination of toxic compounds, which were previously omitted in the model. Numerical simulations of the revised model suggested that while the ethanol concentration is constant, the lifespan still stays limited. However, if ethanol is supplied periodically, with a suitable frequency and amplitude, the dauer could survive as long as we observe the system. Analytical methods further help to explain how feeding frequency and amplitude affect lifespan extension. Based on the comparison of the model with experimental data for fixed ethanol concentration, we proposed the range of feeding protocols that could lead to even longer dauer survival and it can be tested experimentally.

Hair Art Study with Four Elements as Motif: Focusing on Water, Fire, Air, Earth

Humans have long been interested in exploring what fundamental materials make up the world, and tried to understand the world by discovering what are essential substances that make up all things. Therefore this research produced four up-style hair art works of water, fire, air and earth, inspired by four elements. In order to express fluidity and liquidity of water, Work 1 consists of hair art with contrasting soft and rough textures. In order to express flaming quality of fire, Work 2 consists of hair art with contrasting expressions of gentle warmth, intense heat from rising flames, and the element of death. In order to express dynamic properties of air, Work 3 consists of hair art with contrasting aspect of rising and falling. In order to express sturdiness of earth, Work 4 consists of hair art with contrasting qualities such as stability of resting and losing sense of directions. Researching works through these four elements reveal various materials and topics, that can become infinite source of inspiration. Hence, it’s necessary to view creative works from diverse perspectives, not limited to certain topics. Future studies on hair art could focus on further exploring various materials and subjects.

Development and application of a new calculation method for double spiral ground heat exchangers

This study provides a new calculation method for double spiral pipe ground heat exchangers (GHEs) and involves the combination of the analytical, infinite line source (ILS), and infinite cylindrical source (ICS) models with the capacity resistance model (CaRM). Method adopts the concept of fin efficiency, enabling it to calculate underground temperature changes easily and accurately, followed by integration into a simulation tool for ground source heat pump (GSHP) systems. Verification was done by comparing simulation results with actual operating data, measured from a zero-energy building (ZEB) in Sapporo, Japan. Analyses conducted using the new calculation method prove that simulation results can be obtained with increased precision and validity. Under conditions of instantaneous large heat injection, significant differences were observed between the simulation and the actual measurements during the initial 50 h. The number of temperature nodes in the network was increased to effectively reduce the error between simulations and measurements. Moreover, it was seen that the efficiency of double spiral pipe GHEs can be potentially improved by shortening the spiral pitch. This study thus confirms that the proposed new calculation method can be applied to future designs of GSHP systems by using thermal piles with double spiral pipe GHEs.

Geometrical and physical interpretation of the Levi-Civita spacetime in terms of the Komar mass density

We revisit the interpretation of the cylindrically symmetric, static vacuum Levi-Civita metric, known in either Weyl, Einstein–Rosen, or Kasner-like coordinates. The Komar mass density of the infinite axis source arises through a suitable compactification procedure. The Komar mass density mu _{K} calculated in Einstein–Rosen coordinates, when employed as the metric parameter, leads to a number of advantages. It eliminates double coverages of the parameter space, vanishes in flat spacetime and when small, it corresponds to the mass density of an infinite string. After a comprehensive analysis of the local and global geometry, we proceed with the physical interpretation of the Levi-Civita spacetime. First we show that the Newtonian gravitational force is attractive and its magnitude increases monotonically with all positive mu _{K}, asymptoting to the inverse of the proper distance in the radial direction. Second, we reveal that the tidal force between nearby geodesics (hence gravity in the Einsteinian sense) attains a maximum at mu _{K}=1/2 and then decreases asymptotically to zero. Hence, from a physical point of view the Komar mass density of the Levi-Civita spacetime encompasses two contributions: Newtonian gravity and acceleration effects. An increase in mu _{K} strengthens Newtonian gravity but also drags the field lines increasingly parallel, eventually transforming Newtonian gravity through the equivalence principle into a pure acceleration field and the Levi-Civita spacetime into a flat Rindler-like spacetime. In a geometric picture the increase of mu _{K} from zero to infty deforms the planar sections of the spacetime into ever deepening funnels, eventually degenerating into cylindrical topology in an appropriately chosen embedding.

Field hydrothermal identification with groundwater flow by conducting Distributed Thermal Response Test (DTRT) through Moving Line Source (MLS) theory

Thermal Response Test (TRT) is conventionally used to get the ground thermal properties by using Infinite Line Source (ILS) method. However, ILS method gets abnormally ground thermal conductivity when there is an apparent groundwater flow. Moreover, traditional TRT is not able to identify the ground thermal properties along the vertical profile, misleading the hydrogeological engineering applications. In this investigation, ILS and Moving Line Source (MLS) models considering the variation of time were adopted to estimate the ground hydrothermal properties along a heat exchanger with different heating loads by Distributed Thermal Response Test (DTRT). The results showed that carrying fluid temperature gradient varies in different layers, attributed to the variation of ground hydrothermal properties. Thermal conductivity is overestimated by ILS for layers with groundwater flow, while MLS estimates more realistic values. Specifically, thermal conductivity, ground thermal resistance obtained by ILS method can be respectively 2240 %, 66.7 % higher than the values obtained by MLS method, for the layer with apparent groundwater flow. The groundwater velocity was generally underestimated by MLS, and a parameter was adopted to get the real Darcy velocity. In addition, the heat load influences the TRT results, especially when there are boundary effects or the presence of groundwater flow. A higher heat load leads to more reliable ground hydrothermal properties, and it is recommended that the heat injection rate remains between 30 and 70 W.m−1. Test time is also important in TRT, and a test duration longer than 30 h is recommended to reach stable ground hydrothermal properties illustrated by ILS and MLS methods. The investigation is helpful to give guidance for the design of Ground Source Heat Pump (GSHP) systems, especially for the stratified ground with apparent groundwater flow.

A spectral method for the depth-separated solution of a wavenumber integration model for horizontally stratified fluid acoustic waveguides

The wavenumber integration model is the most precise approach for assessing arbitrary horizontally stratified media within the sphere of computational ocean acoustics. Unlike the normal-mode approach, it considers not only discrete spectra but also continuous spectral components, resulting in fewer model approximation errors for horizontally stratified media. Traditionally, the depth-separated wave equation in the wavenumber integration model has been solved using analytical and semianalytical methods, and numerical solutions have been primarily based on the finite difference and finite element methods. This paper proposes an algorithm for solving the depth equation via the Chebyshev–Tau spectral method, combined with a domain decomposition strategy, resulting in the development of a numerical program named WISpec. The algorithm can simulate the sound field excitation not only from a point source but also from an infinite line source. To that end, the depth equations for each layer are first discretized through the Chebyshev–Tau spectral method and subsequently solved simultaneously by incorporating boundary and interface conditions. Representative numerical experiments are presented to validate the accuracy and speed of WISpec. The high degree of consistency of results obtained from different software tools running the same configuration provides ample evidence that the numerical algorithm described in this paper is accurate, reliable, and numerically stable.

Numerical simulation of the thermal wave induced by a moving interfacial heat source with respect to Christov–Cattaneo's equation

AbstractThe hyperbolic wave equation of heat conduction with respect to Christov's formulation is utilized with the Streamline‐ Upwind‐Petrov‐Galerkin method in space and the Θ, Houbolt, linear acceleration, Wilson‐Θ and Newmark methods in time. The derivation of this equation and its matrix formulation are shown. A 2D transient finite element simulation of a generic asperity with an infinite line heat source in an interface, either as a heat flux density q̇ or temperature distribution T, is performed for Math = [0.5; 1.0]. A sensitivity study is presented for the mentioned numerical schemes. The temperature jump in the solution is interpreted as an indicator for a thermal shock.

A spectral method aimed at explaining the role of the heat transfer rate when the Infinite Line Source model is applied to Thermal Response Test analyses

The present paper introduces new concepts related to the modeling of vertical Borehole Heat Exchangers for Ground Coupled Heat Pump applications. A sensitivity analysis on how specific parameters affect the ground thermal conductivity kgr estimation when the Infinite Line Source model is used to interpret a Thermal Response Test has been performed. The study has been conducted considering shallow and deep BHEs, with and without geothermal gradient, and for homogeneous and stratified ground thermal conductivities. The qratio parameter scales the external heat rate to a natural heat rate associated with the geothermal gradient. The effect of qratio on the TRT analysis has been related to a specific dimensionless g-transfer function called g0, which incorporates the geothermal gradient. Three in-house built Fortran90 codes implementing the finite-difference models related to coaxial, single and double U-BHE geometries are exploited to evaluate the dimensionless g-transfer functions related to each fluid volume. A spectral method aimed to reconstruct the fluid temperature profiles by superposing two separated convolutions in the time domain exploiting the Fast Fourier Transform leads to considering qratio as the dominant parameter when the ILS model is used to estimate kgr. In the case of a single-layered subsurface, qratio >>1 guarantees the correct ILS-based kgr estimation for any BHE geometry. In the coaxial center-pipe inlet case with a single-layered subsurface and qratio<1, the ILS-based kgr estimation when the g0-function is taken into account can differ by -14% from the correct ILS-based kgr estimation without taking into account the g0-function. In the case of a multilayered subsurface, the qratio parameter indicates when the effective kgr estimated by the ILS model departs from the weighted-thickness average. A departure of 10% occurs for qratio between 2 and 2.5 for the coaxial center-pipe inlet cases considered and the departure increases with decreasing qratio.

Detecting pipeline leakage using active distributed temperature Sensing: Theoretical modeling and experimental verification

This paper presents a feasibility study on leak detection of buried pipelines using the active distributed temperature sensing (ADTS) method. The proposed solution involves the use of actively heated fiber optic (AHFO) cables arranged parallel to the pipelines, allowing for changes in the thermal properties of the surrounding soil to be captured and correlated with leakage accidents. This problem was modeled as an infinite cylindrical or linear heat source buried in porous media with seepage flowing inside. AHFO sensors were designed to verify the proposed method through scale-reduced model tests. The fiber optic temperature sensing technology based on optical frequency domain reflectometry (OFDR) was used to continuously monitor temperature profiles. The test results demonstrate that the ADTS solution has greatly improved the accuracy of passive temperature sensing methods. The feasibility of the solution was evaluated regarding different levels of leakage estimation, namely, identification, location, and quantification. This paper presents the first attempt to monitor the infiltration process associated with pipeline leaks using the AHFO-OFDR technique, which is a reliable method for structural health monitoring of underground pipelines.

Signatures of an energetic charged body streaming in a plasma.

A charged body moving in a plasma can excite a variety of linear and nonlinear waves in the form of trailing wakes, fore-wake shocks, and precursor solitons. These structures can further interact with the background plasma to create secondary effects that can serve as signatures of the passage of the charged body. Using particle-in-cell simulations, we carry out a basic investigation of the dynamics of a plasma system that is being traversed by an energetic charged body. Using two different shapes of this charged source, namely, an idealized infinite length planar source and a two-dimensional thin rectangular source, we examine the differences in the nature of the excited wave structures and their consequent impact on the background plasma. Our simulations reveal interesting features such as the dependence of the precursor speeds on the total charge on the driving source, local particle trapping, and energization of the trapped particles in various regions along the traversal path leading to the formation of energetic charged beamlets. Our basic findings could find practical applications such as in analyzing the trajectories of charged objects like space debris orbiting in the ionosphere.

Effect of seepage condition in geological stratification on thermal response test analysis of borehole heat exchanger

Determination of ground thermal properties is the prerequisites for the design of ground-coupled heat pump systems (GCHPs), and it is crucial for evaluating the thermal performance of borehole heat exchangers (BHEs). These parameters are usually obtained by in-situ thermal response test (TRT) based on infinite line source model (ILSM). Though the effect of the groundwater flow on the estimation of ground thermal parameters is considered in homogenous ILSM, the estimated deviation can be enlarged as seepage condition varies based on the BHE model in practical geological stratification. Based on the developed numerical layered seepage BHE model (NLSBM), this paper evaluates the effects of seepage location and seepage velocity on estimated accuracy of borehole thermal resistance and ground thermal conductivity. Relative error (RE) between effective thermal conductivity λeff and the thickness-weighted thermal conductivity λTW will be up to 30.5% with the increase of the thickness of the seepage layer. The relative error between λeff and λTW increases from 5.3% to 93.5% when seepage velocity changes from 1 × 10−6 m/s to 1 × 10−4 m/s. The minimum RE between borehole thermal resistance Rb,NLSBM and effective borehole thermal resistance Rb,eff is still up to 37% when seepage locates in the 5th layer. With the increase of the seepage velocity, the RE between Rb,eff and Rb,NLSBM is enlarged, and the minimum RE is up to 29.4% corresponding to the lowest seepage velocity of 1 × 10−4 m/s. The change of seepage velocity or seepage location has little effect on Rb,NLSBM, and the highest RE is only 0.2%.

Apparatus Development for the Measurement of the Thermal Conductivity of Geothermal Backfill Materials

This paper describes the design, construction, validation, and calibration of a thermal conductivity measuring apparatus for geothermal backfill materials in the range from 0.13–2.80 W/m·K. The developed apparatus is based on the Transient Hot Wire (THW) method whose mathematical basis is the Infinite Linear Source (ILS) model. The apparatus consists of a nichrome hot wire, an adjustable direct current power supply, a temperature sensor (K-type thermocouple), and a datalogger. For the validation and calibration of the developed apparatus, four standard samples have been used with a known thermal conductivity, to 3.0 W/m·K. Furthermore, the thermal conductivity of four geothermal backfill materials of common use (bentonite, neat cement, cement–sand mortar, and cement–bentonite mortar) has been measured using both the developed apparatus and a commercial meter.

Sensitivity analysis of a single server finite-source retrial queueing system with two-way communication and catastrophic breakdown using simulation

In this paper, a finite-source retrial queueing system with twoway communication is investigated with the help of a simulation program of own. If a randomly arriving request from the finite-source finds the single server idle its service starts immediately, otherwise it joins an orbit from where it generates retrial/repeated calls after a random time. To increase the utilization of the server when it becomes idle after a random time an outgoing request is called for service from an infinity source. Upon its arrival if the server is busy, it goes to a buffer and when the server becomes idle again its service starts immediately. requests arriving from the finite-source and orbit are referred to as primary or incoming ones while requests called from the infinite source are referred to as secondary or outgoing requests, respectively. The service times of the primary and secondary requests are supposed to be random variables having different distributions. However, randomly catastrophic failures may happen to all the requests in the system, that is from the orbit, the service unit, and the buffer. In this case, the primary requests return to the finite-source, and the secondary ones are lost. The operation of the system is restored after a random time. Until the restoration is finished no arrivals and service take place in the system. All the above-mentioned times are supposed to be independent random variables. The novelty of this paper is to perform a sensitivity analysis of the failure and restoration/repair times on the main characteristics to illustrate the effect of different distributions having the same average and variance value. Our aim is to determine the distribution of the number of requests in the system, the average response time of an arbitrary primary request without successful service, also the average response time of an arbitrary and successfully served primary request, the total utilization of the service unit, or the probability that a primary request leaves the system without successful service because of a catastrophic event. Results are illustrated graphically obtained by our simulation program.

Paper-based evaporation concentrators: Comparison of linear and radial geometries.

Paper-based evaporation concentrators with linear and radial geometries are compared. A new method of finding approximate analytic solutions of the advection-dispersion equation is proposed, based on the behavior of concentrators with infinite sources. Analytic approximations are compared with numerical solutions, and the advantage of radial concentration is highlighted: linear concentration rates scale with the square root of the Péclet number Pe while radial rates scale with Pe itself, leading to faster radial concentration beyond a critical value. Experiments are performed with Brilliant Blue FCF dye, using optical transmission and the Beer-Lambert law for quantitation. Dye concentrations are chosen for operation in the linear absorbance regime. Radial concentration is demonstrated under ambient conditions on filter paper disks with 60 mm diameter evaporation areas fed from a perimeter source, in a reverse of the well-known "coffee stain" experiment. Airflow enhanced concentration in strips and wedges is compared directly, using laser-patterned chromatography paper. The advantage of radial concentration is confirmed (and enhanced by diversion of concentrate to the corners of strips) and concentration factors greater than (the dynamic range of measurement) are obtained in ∼2 h using 30 mm long columns.

Estimation of Groundwater Flow Rate by an Actively Heated Fiber Optics Based Thermal Response Test in a Grouted Borehole

AbstractThe thermal response test (TRT) in an aquifer establishes a relationship between the groundwater flow rate and the recorded temperature response curve of temporal ground heating. A major challenge for achieving a mature hydrogeological field test is to minimize borehole effects by smart practical solutions of in situ heating and temperature sensing. When borehole effects are substantial, concepts are needed to separate their contribution to the recorded signal. This is especially the case when heating and sensing devices are installed in grouted boreholes as permanent testing stations. Interpretation of a recorded response curve thus means solving a transient heat transfer problem with radial conduction through composite media. Here, a series of numerical models are set up to study the effect of the grout and the jacket of an actively heated fiber‐optic cable on the simulated thermal response measured along a heated borehole. The findings are utilized to further develop existing groundwater flow rate estimation procedures based on the moving infinite line source model. The developed approach is demonstrated in a case study in a borehole near a bank collapse site that penetrates different aquifer layers. Accordingly, significant local groundwater flow rates (9 × 10−7–5 × 10−6 m·s−1) are found that vary with depth. The values derived by the TRT interpretation closely match the expected rates (2 × 10−6–7 × 10−6 m·s−1), which supports the good applicability of the estimation procedure in the field.