Heat Storage Process Research Articles

A numerical model coupling multiple heat transfer modes to develop a passive thermal management system for logging tool

Logging tools are subjected to increasingly extreme thermal environments due to the exploration of deeper wells. Previous studies have shown that passive thermal management systems have successfully protected electronics that operate in high ambient temperature environments for up to several hours. However, the percentage of the contribution from different heat transfer modes remains unclear, and the numerical models remain incomplete. To solve this issue, a 3D numerical model that couples all heat transfer modes was proposed for passive thermal management systems of logging tool. Unlike previous simplistic models, the one proposed here considers solid heat conduction, natural air convection, thermal radiation, and the phase change heat storage processes. The accuracy of the proposed model was verified by experiments. The experimental results showed that the maximum absolute errors and the average absolute error between the simulation and experiment were 8.61 °C and 3.02 °C, respectively. The maximum percentage error between the experiment and simulation using the proposed model was 4.71 %, compared to 6.59 % for the previous model. Importantly, the heat transfer process was described in detail by numerical simulations. The results showed that the absorbed heat of the phase change materials accounted for 72.7 %, which suppressed the temperature rise of the heat sources. In addition, the proportions of thermal conduction, convection and radiation in the total heat exchange were 93.89 %, 4.32 %, and 1.79 %, respectively.

Synergistic improvement of melting rate and heat storage capacity by a rotation-based method for shell-and-tube latent thermal energy storage

• Convection is enhanced with the lower-half PCM rotated to the top. • Low-speed rotation can’t avoid deterioration of uniformity caused by reverse flow. • High-speed rotation could be equivalent to the single rotation when f R =0.5. • Liquid fraction is chosen for judging the moment of executing single rotation. • Effects of single rotation enhance with the increase of LTES size. Rotation is emerging as a novel heat transfer enhancement technique for latent thermal energy storage (LTES) due to its superiority in concise control of rotation conditions and significant effects of heat transfer enhancement. However, the detailed mechanism of heat transfer enhancement triggered by rotation and optimization of rotation conditions have been hardly concerned and explained in previous studies. This study aims to illustrate the effects of rotation on the total melting time, heat transfer rate as well as temperature uniformity of LTES during the heat storage process. Firstly, the effects of constant rotation on the heat storage process are investigated. Then the single rotation of 180° is proposed and effects of the moment to implement the rotation are discussed. Finally, the effects of the single rotation of 180° are examined under different sizes of LTES. Results indicate that convection caused by rotation inside the LTES enhances the melting process, and the effects enhance with the increase of rotation speed. It is also found that the 180° inversion of LTES significantly improves the intensity and range of convection, which has similar effects to the constant rotation. Quantitively, applying the single rotation when f R =0.5 leads to the maximum reduction in total melting time of 533.7%, which is close to the 610.3% for the case with the highest rotation speed of 1 rpm. The positive effects of single rotation on enhancing the melting rate and heat storage density become much more obvious under the larger size of LTES.

A TREE-SHAPED LAYOUT HEAT PIPE TO ENHANCE HEAT TRANSFER IN A PHASE-CHANGE MATERIAL STORAGE PROCESS

Phase-change materials (PCMs) are promising in energy storage. However, the low thermal conductivity of a PCM limits its practical application. A tree-shaped layout heat pipe has been studied in this paper to improve the heat transfer performance in PCM energy storage. Based on the thermal imaging picture distribution of conventional heat pipes within the PCM during the heat storage process, tree-shaped layout heat pipes have been designed. Additionally, their thermal performance was experimentally compared with that of conventional heat pipes. Experimental results prove that the bending of heat pipes has little influence on its own thermal performance, and the difference in average temperature between tree-shaped layout and conventional heat pipes is 0.9%. A PCM containing such tree-shaped layout heat pipes melts 15.2% faster than a PCM with conventional heat pipes. The thermal resistance of a PCM with these tree-shaped layout heat pipes decreases by 41.7% compared with that of a PCM with conventional heat pipes. Moreover, tree-shaped layout heat pipes reduce the thermal resistance of the PCM mainly before phase change in the melting process, while this layout has less impact after the completion of melting.

EXPERIMENTAL STUDY ON HEAT STORAGE AND RELEASE OF EG/Li2CO3-Na2CO3 HIGH-TEMPERATURE PHASE-CHANGE HEAT STORAGE UNIT

In this paper, a shell-and-tube high-temperature phase-change heat storage unit used in solar high-temperature phase-change heat storage systems was designed and manufactured by using 5:95 expanded graphite EG/Li<sub>2</sub>CO<sub>3</sub>-Na<sub>2</sub>CO<sub>3</sub> as heat storage medium. The temperature distribution, heat exchange efficiency, and energy efficiency of the heat storage unit were studied by testing the heat storage and heat release processes. It was found that a thermostatic platform appeared in the lateral temperature distribution, and a distinct layered distribution appeared in the longitudinal temperature distribution. When the heating power of the heat storage unit is 640 W, the exothermic air flow rate is 400 L/min, and the phase change material was completely melted, the total heat storage and latent heat of the phase change material are 12,321 kJ and 4466 kJ, respectively. The proportion of the latent heat was 0.36, heat storage efficiency and heat release efficiency are 0.57 and 0.47, respectively. In addition, it was also found from the experiment that the greater the heating power, the higher the heat storage efficiency of the heat storage unit, and the greater the heat release air flow, the higher the heat release efficiency.

Numerical analysis on lunar heat storage system: Multi-objective optimization, heat storage capacity, and thermal insulation performance

The long lunar night of 14 earth days without solar radiation has become the biggest obstacle to the continuous energy supply system day and night. The lunar base heat storage system is one of the best solutions because it is possible to transfer energy from day to night for power generation. However, due to the diversity of energy demands of the lunar base, it is inevitable to study the thermal storage performance of the heat storage system at different periods. In this paper, based on three objective parameters: effective time of heat storage (teff), heat storage capacity (Q), and system entropy increase (Sgen) of the heat storage process, a multi-objective optimization design of heat storage system is carried out. In addition, to solve the heat dissipation problem of the lunar night, the natural lunar regolith insulation layer was added to evaluate the heat storage and insulation of the lunar night. The results show that different types of the heat storage system can be obtained by changing the structure parameters. The heat storage efficiency of the heat storage system with a large radius is still 0.59 after a long period of heat storage. The minimum thickness of the varied-temperature layer can be reduced to 60 % of the height of the whole system. Additionally, the insulation layer can effectively reduce energy loss at night, but the effect of improving thermal insulation performance is limited when the insulation layer thickness is too thick.

Mitigation of lithium-ion battery thermal runaway and inhibition of thermal runaway propagation using inorganic salt hydrate with integrated latent heat and thermochemical storage

Thermal runaway and its propagation in lithium-ion batteries is a severe problem that can result in fire or explosion. In this study, we propose an innovative thermal storage material that integrates latent heat and thermochemical storage to protect the battery during thermal runaway. Sodium acetate trihydrate-urea/expanded graphite—an inorganic salt hydrate—undergoes a solid-liquid phase change at 50.3 °C, with a corresponding latent heat storage density of 181 kJ/kg, and thermal decomposition at 114.0 °C, with a corresponding thermochemical storage density of 567.3 kJ/kg. The latent heat storage density ensures that the battery remains cool during minor accidents, such as an external short circuit, and the dual-stage thermal storage effectively suppresses thermal runaway propagation due to severe accidents involving the thermal or mechanical abuse of the battery. We also establish a mathematical model to describe the multistage latent heat and thermochemical storage processes and predict their impacts on battery temperature. The numerical results were in good agreement with the experimental data, with a maximum error of less than 5%. Compared to conventional phase change materials, the thermochemical storage of the inorganic salt hydrate provides a high thermal storage density at a safe temperature. Thus, the proposed thermal storage material can effectively prevent the incidence and propagation of battery thermal runaway.

Contribution degree analysis of phase change capsule size in packed bed

The phase change capsule packed bed has been widely studied by many scholars because of its simple structure and high heat transfer rate. This study aims to obtain the effect of phase change capsule size on the thermal properties of the packed bed and the variation of the contribution degree in the heat storage process. In this paper, three three-dimensional models of heat storage packed beds with different phase change capsules sizes are established and the thermal storage process is numerically simulated by Fluent. The simulation results are compared with the experimental results, and the results are in good agreement. By monitoring the temperature of the heat transfer fluid (HTF), the temperature of the phase change material (PCM), and the liquid phase fraction in the packed beds with different phase change capsule sizes, the indicators for characterizing thermal characteristics of heat storage devices, such as heat storage rate, heat storage density, instantaneous energy efficiency, and exergy efficiency, can be calculated. The comparative analysis shows that the thermal properties of the packed bed improve as the capsule size decreases. Then the contribution degree of phase change capsule size to the heat storage process of the packed bed is obtained by the chain rule. Results indicated that as the phase change capsule size decreases, its contribution degree increases gradually. Still, the degree of increase decreases, and the gain from the change in capsule size decreases. The contribution degree of the phase change capsule size is also numerically less than that of the inlet mass flow and temperature. In general, with the decrease of the phase change capsule size, the thermodynamic performance of the packed bed and the contribution degree of the phase change capsule size increase significantly, but the power consumption and cost of packed beds increase.

Studying the advantages of equal curvature curved fin to enhance phase change heat storage

Strengthening the heat storage process is the most important means for its application of the phase change heat storage system. By adding fins to the phase change material, the heat transfer area can be expanded and consequently effectively accelerates the heat storage rate. Therefore, this paper proposed a new fin optimization method: the combination of fins of different structures under non-uniform arrangement conditions. This study proposed an equal-curvature curved fin structure based on straight fin. Then, under the same amounts of fins and heat transfer area, the heat storage system with curved fin and straight fin were studied and analyzed. Moreover, by comparing with straight fin, the effect of the combined curved and straight fins on the performance of heat storage system with different arrangements was exhibited and discussed. The results indicated that curved fins have the effect of enhancing heat transfer by comparing with a straight fin. However, the combined curved fin and straight fin with uniform arrangement has no obvious advantage over straight fin model. Compared with the uniform arrangement, under the condition of non-uniform arrangement, the melting performance of the curved fin and straight fin combination models was improved by 24.5 % at most and at least 9.2 %, the melting performance of the straight fin model is improved by 7.7 %. Finally, the results of the optimization method proposed by other scholars are compared to prove that the optimization method proposed in this study is feasible. This work provides the new ideas for fins design with different structures and non-uniform arrangement of heat storage system.

A comparison of steady-state and transient modelling approaches for the performance prediction of solar air heaters

• A transient solar air heater model using high resolution weather data is developed. • Transient model is compared to stationary model using hourly averaged weather data. • Steady approach results in large deviations, especially under variable cloud cover. • Large differences between approaches in useful energy above threshold temperatures. • Potential implications for latent heat storage, solar drying and other processes. Due to the nature of solar energy, the operation of solar air heaters is fundamentally transient, but most mathematical modelling published to describe their behavior has used stationary models coupled with hourly-averaged weather data. Little attention has been paid to the transient behavior of solar air heaters under real, highly variable weather conditions. In this study, the common modelling approach using a steady-state description of solar air heaters is compared to predictions of using a transient model to which minute resolution weather data is given as input. The steady-state approach was found satisfactory, although not optimal, only under clear sky conditions, with relatively small outlet air temperature errors compared to the results obtained with the transient model. Under less favorable conditions with partial cloud cover, the outlet air temperature with the transient model presented large variations due to the sudden changes in solar radiation not captured in the steady-state approach. With the solar air heater parameters employed, instantaneous deviations of almost 15 °C were found, as well as errors in the predicted useful energy above threshold temperature levels. These results support the use of transient models of solar air heaters and high resolution weather data for accurate, short-term modelling of solar drying, latent heat storage and other highly temperature dependent processes.

Thermochemical heat storage performance of CaO particles under fluidization in coupled CaO/Ca(OH)2 cycles and CaO/CaCO3 cycles

The sintering of CaO in CaO/CaCO3 heat storage cycles and the agglomeration of CaO in CaO/Ca(OH)2 heat storage cycles are the main reasons for the decay in heat storage performance of CaO-based materials, respectively. In this work, a novel CaO/Ca(OH)2/CaCO3 coupling process using limestone under fluidization was proposed to realize the sequential CaO/Ca(OH)2 heat storage and CaO/CaCO3 heat storage. The exothermic performance of CaO particles under fluidization in the CaO/Ca(OH)2/CaCO3 coupling heat storage process were investigated. Two coupling modes were compared according to the different feeding methods of fresh CaO particles. The maximum exothermic temperature of CaO particles in the optimal coupling mode reaches 456.9 °C in the first CaO/Ca(OH)2 cycle and 783.8 °C in the first CaO/CaCO3 cycle, respectively. The interaction mechanism between CaO/CaCO3 heat storage cycles and CaO/Ca(OH)2 heat storage cycles was determined. The volume shrinkage caused by the sintering of CaO in CaO/CaCO3 cycles improves the volumetric energy density of CaO particles in CaO/Ca(OH)2 cycles. After introducing 10 CaO/CaCO3 cycles in the first coupling step, the energy density of CaO particles in CaO/Ca(OH)2 cycles is improved by 190 %. The CaO/Ca(OH)2 cycles reactivate carbonation activity of CaO particles in CaO/CaCO3 cycles by increasing porosity of CaO. Therefore, after introducing 10 CaO/Ca(OH)2 cycles in the first coupling step, the carbonation conversion of CaO particles increases by 64.7 %. This work provides a novel and promising heat storage process by integrating efficient CaO/Ca(OH)2 and CaO/CaCO3 cycles under the fluidization.

Numerical study using lattice Boltzmann method on melting and solidification of NEPCM placed inside a rectangular cavity with a new double-fin arrangement

Adding fins to improve the efficiency of LHTES (Latent heat thermal energy storage) systems is a commonly followed measure. Significant research has been conducted on the role of unequal fin-lengths in the heat-storage process. However, the literature does not contain a detailed treatment of the enhancement effect of unequal fins on heat release. In this study, the geometric symmetry of the melting system is inverted to reduce the blocking effect of unequal fins on solidification. Three groups of LHTES systems, with different length ratios and without fins, were compared. A composite PCM composed of paraffin and copper oxide was used to simulate the phase change process of the LHTES system under natural convection by using the LBM model based on enthalpy at constant wall temperatures of 343 and 323 K. This study found that compared to the design without fins, the melting times were reduced by 16.7 %, 22.55 %, and 33.06 % when the length ratios of the three groups of fins were 1, 0.6, and 0.3333, respectively, and the solidification times were reduced by 57.54 %, 50.99 %, and 47.33 %, respectively. When only a single melting process is considered, unequal fin-lengths with large differences in length are selected. When considering the comprehensive process of heat storage and release, fins with equal lengths are a better choice.

Study of the Phase-Change Thermal-Storage Characteristics of a Solar Collector.

A combined solar phase-change thermal-storage heating system is proposed, wherein erythritol is used as the phase-change material (PCM) used to fill the thermal-storage device, and the storage cavity is heated and stored with a disc concentrator. The Solidification/Melting, Volume-of-Fluid (VOF) model of ANSYS Fluent software was used to simulate the phase-change process of erythritol inside the thermal-storage device. The thermal-storage device was designed based on our numerical calculations, and its performance was tested. We found that larger PCM-volume fractions correlated with lower PCM volume-expansion rates and longer total melting times during the heat storage process. When the φ value equaled 80%, the PCM solid-liquid-phase interface and temperature distribution were most uniform and showed the best heat storage. In addition, the size of the heat-storage device affected the heat-exchange area, and the total melting time of the PCM decreased and then increased as the width-to-height ratio (I) increased. With this design capacity, the late stage of the charging process of the heat-storage device accounted for 70% of the total time, and the heat energy-utilization rate during the boiling process was 66.3%. Overall, this combined heating system can be considered a very efficient solar energy-utilization terminal for basic domestic energy needs.

Thermo-Economic Assessments on a Heat Storage Tank Filled with Graded Metal Foam

To save and better deploy waste heat, the use of a mobilized heat storage system (MHSS) with phase change enhancement means is developed. In this paper, three kinds of gradient structures (positive gradient, negative gradient, and non-gradient) are designed in the MHSS system. The uniform porosity is 94% in the non-gradient structure, and the gradient porosities are 86%, 93%, and 98% in the gradient structure, respectively. Numerical models are developed to explore the contribution of the graded metal foam structure to the heat storage and release process. An economic analysis and comparison of MHSS systems with different heat transfer models are carried out. The results show that the positive gradient case can promote the thermal cycle of the melting and solidification process, while the negative gradient case inhibits the thermal cycle. The positive gradient case can reduce the melting time by 9.7% and the solidification time by 4.4%, while the negative gradient can prolong the melting time by 31.4% and the solidification time by 35.9%. Although graded metal foam increases the initial investment by 76.09%, the 1 KW·h heat cost of graded metal foam is reduced by 10.63% compared to pure phase change material (PCM). It is cost-effective in the long run of thermal cycles.

A comprehensive model and its optimal dispatch of an integrated electrical-thermal system with multiple heat sources

As essential parts of the combined heat supply network with multiple heat sources, the electrical-heating and heat storage technology can simultaneously achieve the goal of clean heating and renewable energy accommodation. The paper introduces the integrated electrical-thermal system with multiple heat sources that consist of combined heat and power (CHP), coal-fired boiler (CB), and electrical boiler (EB) with thermal energy storage (TES). Considering the integration of electrical and thermal networks, we construct a comprehensive model that includes the electrical energy transmission and the overall heat transfer and storage processes based on the heat current method. Based on the comprehensive model, the optimal dispatch of the integrated system is discussed, and an iteration solving method is proposed, which can achieve acceptable convergence and solving efficiency. The simulation results show the combined operation of multiple heat sources has higher system operation efficiency but not necessarily a higher utilization rate of renewable energy. In the test system the combined operation of CHP and coal-fired boiler can reduce the coal consumption of the system by 2%. However, the wind utilization of the system decreases by 4.17%. Moreover, the introduction of an electrical boiler with a TES device can improve the system's flexibility and reduce wind curtailment, wherein the test system is 12.11% more wind consumption. Further, the heat load level can affect the operation efficiency of CHP, the combined operation of multiple heat sources can achieve the balance between reducing coal consumption and increasing renewable energy power generation.

Influence of geometrical dimensions and particle diameter on exergy performance of packed-bed thermal energy storage

Expansion of infrastructure acquiring electricity from renewable sources determines the necessity of energy storage technology development. For highly urbanized areas specializing in the exploitation of underground coal deposits, due to the progressive decarbonization process, an adiabatic compressed air energy storage system using post-mining mine shafts has been proposed. The adiabatic character of the system is provided using Thermal Energy Storage (TES) tank, which is designed to be installed in a mine shaft volume. The solution determines unique geometrical dimensions compared to the studied and applied heat storage tanks, which affect both the heat transfer intensity and pressure drop of the flowing medium. This paper presents an exergy analysis of the performance of heat storage tanks on a laboratory scale, which was based on a numerical analysis validated on experimental data. It is shown that as the slenderness of the storage tank increases, the exergy efficiency of the heat storage process increases from 90.7% to 98.5% depending on the geometry studied. For the full cycle of the heat storage performance, exergy efficiency values ranging from 56.2% to 69.0% were obtained depending on the studied geometry.

Experimental and numerical investigation of longitudinal and annular finned latent heat thermal energy storage unit

The melting process of phase change material (PCM) in horizontal latent heat thermal energy storage (LHTES) units with longitudinal and annular fins was experimentally studied under the same fin volume condition. The PCM melting time of the annular fin unit is reduced by 13.7% compared to that of the longitudinal fin unit. The annular fins are more responsive to the increase in heat transfer fluid (HTF) inlet temperature and the longitudinal fins are more responsive to the increase in HTF flow rate. After that, numerical studies were also performed for the two LHTES units to reveal in-depth the differences in heat storage processes. The results show that the longitudinal fins perform better in the early stage due to their larger contact area with the inner tube and a denser distribution near the inner tube. But it also limits the natural convection in the latter stage. The annular fins have better natural convection performance in the latter stage and therefore have better heat storage performance. Based on the analysis, a composite fin was designed to combine the advantages of longitudinal and annular fins. Numerical results show that the newly designed fin results in a 21.6% melting time reduction compared to the longitudinal fin model and a 9.5% melting time reduction compared to the annular fin model. Finally, two principles to guide the fin design in horizontal shell-and-tube LHTES units were summarized.

Lattice Boltzmann modelling on pore-scale reactive transport in exothermic reactions of solid blocks for thermochemical energy storage

In this study, a pore-scale numerical model of plate-type reactor is developed to simulate and analyze the coupled CaO/Ca(OH)2 thermochemical heat storage processes based on the lattice Boltzmann method. In the research, the fluid flow, chemical adsorption, mass and heat transfer during hydration reaction are considered. Three different structures with the same porosity of solid particles are designed: in-line, staggered and random patterns. The heterogeneous reaction model with the Langmuir adsorption kinetics is implemented on gas–solid interfaces. The interparticle and intraparticle mass transfer processes are both involved with the help of the lattice Boltzmann method. The distributions of concentration in the gas phase and adsorbed amount in the solid phase are obtained in detail. The conversion rates under three different structures with similar porosity are also compared. Moreover, conjugate heat transfer is applied to simulate the transient temperature distributions in these structures. Heat is released from the solid particles and diffuse to the surrounding area along with the fluid flow. The maximum temperatures of the three structures are 550℃. Besides, the trends of characteristic temperatures over time are also obtained, and the durations above 500℃ are calculated, reflecting the heat storage performances of the different structures. The heat release of three different structures is also compared. It is proved that the structure with staggered blocks is recommended.

Numerical Investigation of Heat Transfer Performance and Structural Optimization of Fan-Shaped Finned Tube Heat Exchanger

Latent heat storage technology is widely used in solar power generation. Aiming to enhance the energy utilization rate to a greater extent, an innovative fan-shaped structure has been proposed to construct the metal fins of the shell-and-tube thermal storage device. The enthalpy method is used to simulate the heat storage process and focuses on the influence of inlet conditions on heat transfer. The influence of the fin structure on the melting properties of phase change material has been studied. The results show that increasing inlet temperature and inlet flow rate is a convenient and effective way to improve energy efficiency. As the inlet temperature is increased from 343 K to 358 K, the total heat storage and energy efficiency are improved by 13.4% and 10.2%, respectively, and the melting time is reduced by 36.2%. As the flow rate is increased from 3 L/min to 9 L/min, the complete melting time is reduced by 33.4%. Energy efficiency peaks at a flow rate of 5 L/min. Reasonable optimization of the fin structure can enhance the natural convection circulation during the melting process and further improve the energy efficiency. The research results can guide the design and structural optimization of the finned tube heat storage device.

A State of the Art Review on Sensible and Latent Heat Thermal Energy Storage Processes in Porous Media: Mesoscopic Simulation

Sharing renewable energies, reducing energy consumption and optimizing energy management in an attempt to limit environmental problems (air pollution, global warming, acid rain, etc.) has today become a genuine concern of scientific engineering research. Furthermore, with the drastic growth of requirements in building and industrial worldwide sectors, the need for proper techniques that allow enhancement in the thermal performance of systems is increasingly being addressed. It is worth noting that using sensible and latent heat storage materials (SHSMs and phase change materials (PCMs)) for thermal energy storage mechanisms can meet requirements such as thermal comfort in buildings when selected correctly. However, as the operating temperature changes, a series of complex technical issues arise, such as heat transfer issues, leaks, corrosion, subcooling, supercooling, etc. This paper reviews the most recent research advances in the area of sensible and latent heat storage through the porous media as potential technology while providing useful information for researchers and engineers in the energy storage domain. To this end, the state and challenges of PCMs incorporation methods are drawn up, and an updated database of various research is provided while discussing the conclusions concerning the sensible and latent heat storage in porous media, their scopes of application and impact on energy consumption. In the light of this non-exhaustive review, it turns out that the adoption of porous matrices improves the thermal performance of systems, mitigates energy consumption and drops CO2 emissions while ensuring thermal comfort within buildings. In addition, at the representative elementary volume (REV) and pore scales, the lattice Boltzmann method (LBM) is examined as an alternative method to the commonly used, traditional numerical methods. These two approaches are compared based on results available in the literature. Through these means, their ability to handle latent and sensible heat storage process in a porous medium is demonstrated. To sum up, to be more complete, perspectives of sensible and latent energy storage technologies are covered.

Thermal performance analysis of ground source heat pump system for low-temperature waste heat recovery storage

This study investigated the thermal performance of a ground source heat pump (GSHP) system for low-temperature waste heat storage. Considering the large amount of low-temperature heat from industrial effluents wasted to the environment, this study intends to store this low-temperature waste heat in the ground. A GSHP system for low-temperature waste heat storage was established, which could simultaneously achieve heat storage and extraction. In this system, the borehole cluster comprises two parts: inner and outer layers of ground heat exchangers (GHEs). The inner layer was used for space heating as a common GHE, which extracts heat from the ground, whereas the outer layer connected to the industry was designed for injecting low-temperature waste heat to the ground seasonally. The heat fluxes of the GHEs for heat injection and extraction were set differently and were taken as two different strengths of heat sources in this study. A heat and moisture transfer model was established and experimentally validated. Subsequently, the waste heat storage and heat extraction processes are modelled numerically. The results show that the average soil temperature increases by at least 2.63 and 6% when the heat flux of the outer layer GHEs are 40 and 50 Km−1, respectively. It reveals that the injection of low temperature waste heat into the soil is not only beneficial to waste heat recovery, but can also alleviate soil thermal imbalance, providing significant support in heating dominated area, especially in cold regions. This study complements the thermal analysis between two different strength of heat sources, providing a reference for practical engineering design.