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As an alternative energy for fossil fuels, geothermal reserve is abundant. In recent years, scholars have investigated geothermal wells through numerical simulations. To the best of our knowledge, many studies have explored the influence factors of thermal power over time, and few studies have investigated the heat transfer mechanism between wellbore and formation in different circumstances. This paper aims to established a transient numerical heat transfer model of U-shaped closed-loop geothermal system with long horizontal section, which can simulate the temperature distribution and heat transfer mechanism during the whole wellbore formation. In the model, the convection term is discretized by using the second-order upwind scheme, and the finite volume method is used to solve it. The numerical results are proven to be correct by comparing with the field data of a well in China. Subsequently, the influence mechanism of fluid type, insulation casing length, fluid injection temperature, flow rate, and horizontal section length on thermal power is explored. The optimal depth of insulation casing under different injection temperatures, flow rates, and horizontal section lengths is suggested so as to provide crucial guidance for engineering practice. [ABSTRACT FROM AUTHOR]

• A three-dimensional unsteady state mathematical model of the multi-field coupling of backfill body, tube and fracture was established. • A test bench was designed and built to verify the three-dimensional coupling model. • The effects of a single fracture position, aperture and fractured depth on the heat extraction performance of a full-size BFHEs unit in the fully dry or fully saturated conditions were investigated. • The combined effects of multiple fractures on the performance of a BFHES unit were discussed. Thermal hazards in deep mines can be mined synergistically with the deposit as associated geothermal energy resources. Backfill heat exchangers (BFHEs) as a combination of mine backfilling and ground heat exchanger technology are one of the effective methods to realize ore deposit-geothermal energy synergy mining. However, in the complex environment of deep mines, BFHEs will inevitably suffer from fracture damage during long-term heat storage/release cycle operation, which will affect their working performance. To address this problem, this paper established a scaled-down experimental setup for fractured BFHEs units, and used the experimental data to verify the accuracy of the established three-dimensional transient heat transfer mathematical model of the BFHEs unit. Numerical simulation methods were used to investigate the effects of the position, aperture and fractured depth of a single fracture on the heat extraction performance of the BFHEs unit under fully dry or fully saturated working conditions. Significant differences were found in the effect of different fracture positions on the heat extraction capacity of the BFHEs unit. The extraction of geothermal heat by the BFHEs unit was favored when it was in the middle of two tubes, while the opposite was true for other positions. The effect of fracture on the heat extraction capacity of the BFHEs unit increased linearly with fracture aperture. The effect of the fractured depth was relatively greater in the 1/2–3/4 H b range. The presence of groundwater significantly reduced the effect of the fracture. The effect of the fracture on the heat extraction capacity of the BFHEs unit was reduced by more than 80 % by changing the operating conditions from fully dry to fully saturated condition. The overall effect of a fracture on the heat extraction capacity of the BFHEs unit was not significant, with a 5 mm wide fracture having an effect of no more than 2.5 %, even under the fully dry condition. However, there was a combined effect of multiple fractures, and for a deposit size of 900 × 7 × 80 m, ten 2 mm apertures fractures would results in a maximum reduction of geothermal extraction from BFHEs by 8527 GJ in 10 years, which was equivalent to the heat load of a 13,753 m2 building for one winter in the cold climate of China. [ABSTRACT FROM AUTHOR]

The thermal conductivity of rock is an essential thermophysical parameter in geothermal engineering. Experiments have shown that when rock changes from an unsaturated to a saturated state, thermal conductivity can be increased by 50% at most. In this paper, the variation of thermal conductivity with saturation of 101 samples of six different rock types from Songliao Basin, Gonghe Basin, and Ordos Basin in China was measured in the laboratory. Correlations between saturation, porosity, internal structural characteristics of rocks and thermal conductivity were investigated. The results show that the effect of saturation on the thermal conductivity of rock increases exponentially with porosity. Based on three classical models and the relationship between porosity, saturation, and thermal conductivity, improved models and a fitted model of thermal conductivity are proposed. By comparing the improved models to the fitted model, the applicable scope of each model is obtained. The errors of each model are analyzed in detail. The average MAE value of the improved models is 0.405 and the average RMSE value is 1.207 over the applicable model scopes. The R 2 of the fitted model is 0.94. Compared with experimental data from literature, MAE values of the improved models and the fitted model are 0.040 and 0.003 respectively. Unsaturated rock with a single fracture heat transfer model is established by simulation. A thermal-Hydrological coupling model is used to simulate seepage heat transfer through fracture. The effect of variable thermal conductivity simulation is the best with the experimental value, and the MAPE value was 8.3%. This study fills a gap in available models of unsaturated thermal conductivity of rock, and provide theoretical support for the accurate calculation of heat transfer efficiencies in related geothermal engineering applications. • Theoretical saturation coefficient equation on thermal conductivity was proposed. • Three unsaturated thermal conductivity models were improved and verified. • Propose an empirical unsaturated model based on laboratory data. • The relationship between unsaturated model and rocks structure was revealed. [ABSTRACT FROM AUTHOR]

The Experimental Advanced Superconducting Tokamak (EAST) had been under major upgrading from 2020 to 2021 in China. In this campaign of major upgrading, the new lower tungsten divertor is successfully installed to achieve the targets of long pulse and high β H-mode plasma operation. High temperature and high pressure Divertor primary heat transfer system (DIV PHTS) is also developed to remove the plasma deposition heat load on the Divertor. This paper presents a description of the design and construction of DIV PHTS for EAST Tokamak. Starting from the requirements specified in the Technical Specifications of DIV PHTS, the process to meet the Divertor cooling and baking requirement is designed and validated by the supported thermal-hydraulic analysis. Then, the piping stress analysis under different types of load combinations is performed to verify the structural design requirements. General layout design is also performed based on the component requirement and the allocated space in the EAST Tokamak hall. Finally, the procurement and test of the system main equipment is also given. [ABSTRACT FROM AUTHOR]

Highlights • An over-temperature protection system has been designed for the spallation target in CiADS system to prevent the granular target from abnormal irradiation by the accelerator's beam. • In order to evaluate the validity of the protection functions, the spatio-temporal variations of the target temperatures have been investigated with the heat transfer model. • The simulation results can be summarized as follows. (1) Beam scanning can be used to avoid very high temperature at the target center. (2) The granular blockage can also be detected by measuring the temperatures in the four directions. (3) Beam deviation can be detected by comparing the temperatures in the four directions. • Finally, over-temperature protection logic was designed, the accelerator and reactor in CiADS are shut down urgently by removing power from the ECR ion source, allowing the accelerator to urgently shut down its beam. Abstract In an accelerator driven sub-critical system (ADS), a spallation target is irradiated by high-power proton beam to drive a sub-critical reactor. To continuously produce very intense neutrons, it is very important to prevent the unsafe operation of the target. This paper reports an over-temperature protection system for the spallation target in China initiative ADS system, where tungsten granules in the target container are used as both coolant and target materials. In order to protect the target from abnormal irradiation by the accelerator's beam when the granules are blocked or when the beam deviates from the target center, 12 sets of thermocouples are mounted inside the target container to monitor the target temperature. To evaluate the protection functions of these thermocouples, the heat transfer model of particles has been employed to investigate the spatio-temporal variations of the target temperatures when tungsten granules stay static in the target. The simulation results indicate that the temperatures of the thermocouples increase with the irradiation time and the granular blockage can be detected by analyzing the temperatures of these thermocouples. On the other hand, when the beam center deviates from the target center, the azimuthal distribution of the target temperature becomes non-uniform, and the temperature of the thermocouple close to the beam center increases faster. Finally, in the monitoring system for the over-temperature protection, 12 thermocouples divided into 3 groups which are fixed within the target in the upper, central and lower parts of the target, and 4 thermocouples in each group are located in four directions of east, south, west, and north. If two or more channels of four directions in one group exceed the set point, the protective function of granular blockage will be initiated; if two or more channels in one direction are greater than the set point, the protective function of beam deviation will be triggered. [ABSTRACT FROM AUTHOR]

• A PVT collector with a roll-bond absorber is designed for rural home application. • Thermo-laminating is a novel and convenient method for PV-absorber connection. • The validated PVT model can simulate the roll-bond PVT performance accurately. • The model is available for predicting the dynamic performance of PVT systems. This paper mainly investigated the performance of a low-cost roll-bond water-type photovoltaic thermal (PVT) collector from both experimental and modelling approaches under the climatic conditions of Sichuan Basin of China. The design and manufacturing process of the PVT prototype adopted the available commercial PV panels for convenience and for reducing the manufacturing cost. The experiment measured all the main properties of the developed PVT module. The excellent heat transfer performance of its roll-bond absorber plate was also validated by outdoor steady-state tests. Then, the steady-state numerical models were used to simulate the performance of the PVT prototype in TRNSYS. By comparing the simulation and experimental results, two robust models were selected which have their own advantages in charactering the thermal and electrical properties of the PVT collector. Through validating the numerical models with experimental data, the deviation between the simulated and the measured values was further reduced. In addition, a complete photovoltaic thermal–domestic hot water (PVT-DHW) system with such PVT collectors was developed in TRNSYS, by which the annual system output and efficiency were predicted and analysed. [ABSTRACT FROM AUTHOR]

• A new structural design method for earth-to-air heat exchangers in greenhouses is described. • The structural design method incorporates greenhouse heat balance model to better match greenhouse characteristics. • The system is more energy-efficient and stable in intermittent operation mode. • Application of an earth-air heat exchanger is a green technology for greenhouse sustainability. An earth-air heat exchanger (EAHE) is a type of environmental regulation equipment that is suitable for greenhouses. In the future, it could be a green technique for greenhouse energy supplementation. However, EAHEs lack structural design methods for application in greenhouses. Consequently, this paper presents a structural design method for an EAHE based on the architectural characteristics of greenhouses. Firstly, the EAHE design heat exchange amount was calculated according to the greenhouse heat and cold load, then the pipe length, diameter, air velocity, and burial depth were determined by combining the heat transfer efficiency and number of transfer units (NTU), and finally the final parameters were optimized and selected according to the energy loss and construction cost. The design method was validated in a greenhouse in northern China, and the heat transfer performance was analyzed in both intermittent and continuous operation modes. The results showed that the novel structural design method could guide the application of EAHE in a greenhouse and satisfy the energy demand of greenhouses. The measured average greenhouse temperature at night increased by 1.57 °C and 1.11 °C, respectively, under intermittent operation and continuous operation and decreased by 1.19 °C and 1.32 °C, respectively, during the day. The EAHE performance coefficients for heating and cooling conditions under intermittent operation were 21.49 and 18.15, respectively, significantly higher than those for continuous operation. [ABSTRACT FROM AUTHOR]

• A review of the difficulties faced when burning high-alkali coals in boilers. • The effective combustion utilization methods of high-alkali coals are summarized. • The ash deposition solutions of burning high-alkali coals are summarized. • Proposed future research directions for the utilization of high-alkali coals. High-alkali coals are distributed in many countries all over the world, mainly characterized by contains abundant alkali metals and alkaline earth metals (AAEMs) elements, direct combustion in boilers will bring serious ash deposition, fouling, and slagging (ash-related issues) on the metal heat transfer surface of the boilers. In particular, the Zhundong (ZD) coals in Xinjiang, China, as typical high-alkali coal, have a huge reserve that can effectively ensure China's coal demand in the long term. The main purpose of this paper is to clarify the problems and difficulties faced by the combustion of high-alkali coals in boilers, explore and summarize the effective utilization methods. First, the primary difficulties and problems faced by direct combustion of high-alkali coals in boilers are summarized. Second, the research progress of current efficient utilization methods and solutions of high-alkali coals combustion in boilers are summarized and reviewed, it mainly includes the following aspects: (1) pretreatment technology before combustion; (2) control and optimization of combustion parameters such as temperature and atmosphere; (3) co-combustion with inorganic additives, other coals, biomass fuels, and other fuels, respectively. The above methods have been proved can be effectively reduced and alleviated the ash-related issues, but no methods can be eliminated or solved the problems completely at present. Based on the existing research and practice results reviewed in this paper, aiming at the efficient utilization of high-alkali coals combustion in utility boilers, further feasible research directions or key points for the future are proposed. [ABSTRACT FROM AUTHOR]

The rapid development and large-scale penetration of wind power would bring about substantial environmental benefits by substituting fossil fuel-based thermal power generation. In this paper, the environmental co-benefits synergized with energy saving benefit of wind power penetration in China were quantified. Moreover, the regional distribution of environmental co-benefits was mapped by considering the baseline emission factor of each region. Based on the co-benefits analysis results, the wind power deployment pathways were designed to enlarge the environmental co-benefits in the whole country level. The results show that the CO 2 , SO 2 , NO x , and PM 2.5 emissions reduced and water consumption saved due to wind power penetration account for respectively 2.58%, 2.71%, 2.66%, 1.58%, and 2.34% of total environmental emissions and water consumption from the whole power generation sector in China. In view of regional distribution, the environmental co-benefits of wind power to the power system is not proportional to the amount of fossil-fueled power that it displaces. The penetration of wind power results in the largest environmental co-benefits in the North China grid. The Northwest China grid has a higher environmental alleviating potential compared with the Northeast China grid even though the two regions has an equal magnitude of wind power penetration. Scenario analysis suggests that lowering the proportion of thermal power in power generation structure and the transmission of bundled wind power and thermal power from the north to the load centers are promising ways in enlarging the environmental co-benefits of wind power penetration. [ABSTRACT FROM AUTHOR]

In response to the energy conservation and emission reduction targets proposed by China's Fourteenth Five-Year Plan, it is necessary for oilfield enterprises to achieve the purpose of reducing energy consumption and carbon emissions of crude oil storage under the premise of ensuring safe production of oil depots. As the preferred oil storage facility for crude oil depots, the internal heat flow transmission process of storage tanks plays a vital role in the overall energy consumption of oil depots. In this paper, a three-dimensional theoretical model of the heating process of large waxy crude oil tank storage is established, and the influence law of the circumferential effect of the coil on the heating process of waxy crude oil is put forward. The external environment influence area, the internal temperature rise heat flow influence area and the transition area are put forward. The multi-nonlinear regression method is innovatively used to establish the main influencing factor model for each influence area so as to realize the quantitative characterization of the influence mechanism between the heat flux at the tank boundary and the dynamic thermal environment and the variable physical properties parameters of crude oil. The results show that the convective heat transfer of oil in the tank bottom area is greatly influenced by the circumferential effect of the coil, and the circumferential effect of the coil is enhanced with the gradual proximity of the coils on both sides, and the low temperature area at the tank bottom is obviously improved. The heat loss of the storage tank is mainly concentrated at the boundary of the tank. According to the change of heat flux in each boundary area, the external environment influence area, the internal heating heat flow influence area and the transition area are divided. Among them, the top of the storage tank forms an external environmental impact area dominated by solar radiation heat transfer, supplemented by natural convection of temperature difference, and the bottom of the storage tank forms an external soil impact area dominated by heat conduction to the external soil. Due to the effect of the thermal insulation layer, the influence of the external dynamic thermal environment on the position of the tank wall is weakened, and only the influence area of the internal temperature rise heat flow dominated by the natural convection of crude oil is formed. At the same time, there is a transition area with different thickness between the internal and external influence areas, which is affected by the external dynamic thermal boundary conditions and the physical properties of crude oil. The internal heat transfer direction is different, which causes the influence weight of each factor to fluctuate, and with the reduction of the external dynamic thermal environment, the transition area becomes the external condition influence area. • The influence of circumferential effect of coils on heat transfer of crude oil is proposed. • The heat transfer characteristics of the tank boundary region under dynamic thermal conditions are studied. • The external influence area, internal influence area and transition area of the tank are divided. • The main influence factors model of influence area is established. • The relationship between the boundary heat flux of tank and internal and external influencing factors is quantitatively characterized. [ABSTRACT FROM AUTHOR]

Abstract: With attractive advantages of high efficiency, energy saving and environmental friendliness, the ground source heat pump (GSHP) system has been used widely in China in recent years. This paper summarizes the analytical solution, numerical solution and experimental investigation of the heat transfer of the ground heat exchanger (GHE), analyzes the simulation model and long-term operation performance of the GSHP system, and introduces the lastest hybrid ground source heat pump (HGSHP) system. In addition, this paper discusses and summarizes the shortages and imperfects of the current research on the simulation of the GSHP system and gives some recommendations for future work. [Copyright &y& Elsevier]

The content and distribution of pore unfrozen water directly reflect the coal thawing process. It is the key to break through the evolution of coal pore structure under low temperature to study the pore ice melting speed. Taking bituminous coal in Yuan Zhuang, China as the research object, this paper studied pore thawing characteristics of coal samples with different liquid nitrogen freezing time through nuclear magnetic resonance technology. The experimental results clearly demonstrate that appropriate liquid nitrogen freezing time could greatly expand the macropore of bituminous coal, while the expansion effect of micropore and mesopore was less affected by the freezing time. As the freezing time increased, the pores and pore throats of saturated bituminous coal underwent two phases of ice-water transition expansion and liquid nitrogen low-temperature shrinkage. There were differences in the local thermal conductivity of coal samples with different liquid nitrogen freezing time, resulting in different thawing speeds of pore water at the same thawing temperature. When the freezing time increased, the thermal conductivity of coal samples increased due to the pore freezing shrinkage, which can greatly improve the thawing speed of coal samples. Combine the experimental date with heat transfer mechanism to study the thawing speed of the coal frozen by liquid nitrogen. Analyze the unfrozen water distribution and local thermal conductivity in thawing process, which effectively connects the macro-level and micro-level of coal. [Display omitted] • Liquid nitrogen freezing has the best effect on the expansion of macropore in bituminous coal. • The pore structure undergoes two stages of expansion and shrinkage with the increase of freezing time. • The increased freezing time leads to pore freezing shrinkage, which can improve the thawing speed of coal sample. [ABSTRACT FROM AUTHOR]

This paper aims to clarify ash deposition/slagging behavior of the newly found Xinjiang high-alkali coal in China, which is notorious for large amounts of sodium (Na 2 O, 4.0–10 wt%) and calcium (CaO, 20–40 wt%). A 12-h exposure test of ash deposition/slagging was conducted in a 3 MW th pilot plant, with a number of deposition probes and heat transfer tubes being inserted along the furnace to mimic the real pulverised coal-fired boilers. The samples were characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) coupled with Energy Dispersive X-ray Detector (EDX). Thermodynamic equilibrium calculations using FactSage 6.1 were also conducted to interpret the experimental observations. As has been confirmed, the Fe-rich species including magnetite and wollastonite are dominant in the fire-side deposit, due to the low melting temperature of Fe-/Ca-bearing minerals. Those particles were firstly melted and agglomerated to form large clusters, which subsequently attached to cold furnace wall by the inertial force. In convective section, the vaporisation of alkali metals, as well as their subsequent condensation and sulphation reaction to form Na 2 SO 4 and CaSO 4 are the major routes fouling the water tube. Compared to the coal samples studied in the literature, the ash deposit for Xinjiang coal grew quickly in the first 1.5 h, causing a significant decrease on heat transfer efficiency. Na 2 SO 4 , CaSO 4 and Ca–Al–Si slags are the dominant phases in the growing layer of the ash deposit. The continuous interaction between liquid phase and newly captured particles led to the formation of eutectic compounds which embed anhydrite (CaSO 4 ), thenardite (Na 2 SO 4 ), gehlenite (Ca 2 Si 2 O 7 ) and hematite (Fe 2 O 3 ) inside. The formation of these eutectics accelerated the capture of more solid particles in ash deposit, which also turned sticky and harder to remove upon the increase on exposure temperature and time. [ABSTRACT FROM AUTHOR]

Available-geological study shows that the Fushan iron mineralization was mainly controlled by the tectonic deformation, but the roles of both the stretching activity and the squeezing activity in the ore-forming processes are still unclear and under debate. Using coupled structural deformation, heat transfer and pore-fluid flow models to simulate the effect of tectonism on the formation of the Fushan iron deposit can enhance our understanding of the ore-forming processes in the Fushan iron ore district. The three-dimensional numerical model of the Fushan iron deposit was established to simulate the coupled structural deformation, heat transfer and pore-fluid flow. In particular, the finite difference method is used in this paper to simulate the structural deformation, which can affect the formation of the metallogenic region. The simulation results of the Fushan iron deposit indicated that the Fushan iron deposit was formed mainly by compressive squeezing deformation rather than extensional stretching deformation. When the ore district was subject to compressive squeezing deformation, the hydrothermal fluid would be focused in a favorable metallogenic area. [ABSTRACT FROM AUTHOR]

Heat and mass transfer of pyrolytic hydrocarbon fuels at supercritical pressure has important implications for regenerative cooling technology in advanced engines. Based on the detailed chemical kinetic mechanism of China No. 3 jet fuel (a.k.a. RP-3), the heat and mass transfer of RP-3 in a horizontal square cooling channel under asymmetric heating and buoyancy at supercritical pressure is investigated numerically. The results show that buoyancy induces secondary flow. The secondary flow enhances the heat and mass transfer between the near wall region and the core flow field, which can effectively improve the utilization level of fuel heat absorption capacity and suppress the carbon deposition on the surface of the cooling channel. In the case of bottom heating, the dramatic change in fuel density with fuel pyrolysis induces the strongest secondary flow, resulting in the highest fuel heat absorption capacity and the least carbon deposition. In addition, as the operating pressure increases, the buoyancy effect becomes stronger duo to fuel pyrolysis, which is significantly different from the buoyancy effect in the non-cracking zone. Under the buoyancy effect, the increased operating pressure enhances the secondary flow intensity, which reduces the heated wall temperature and suppresses the carbon deposition on the cooling channel surface. The results of this paper are expected to provide further insight into the design and optimization of regenerative cooling technologies. • Heat transfer and surface coking under asymmetric heating and buoyancy were analyzed. • Secondary flow reduced thermal stratification and improved fuel conversion. • Stronger secondary flow intensity resulted in lower wall temperature and carbon deposition. • The increasing pressure accelerated secondary flow and enhanced heat and mass transfers. [ABSTRACT FROM AUTHOR]

Abstract: Snow cover is a common and relatively stable land cover condition in winter for cold north regions in China. Snow cover has significant effects on water and heat transfers in frozen soil; it needs to be considered in the study of frozen soil water–heat coupled movements. On the basis of previous research results and physical process analysis of water and heat movements in snow cover and soil, a snow cover–soil union water–heat coupled movements model is established in this paper. The numerical simulation was conducted by using a finite difference method. The results indicate that the simulated values have a similar trend to the measured values and the numerical simulation had big relative errors. However, the average absolute errors of the total and liquid moisture content in frozen soil were all less than 4%, and that of the frozen soil temperature was 1.37 °C. The errors of the numerical simulation were still within the acceptable range. Thus, the snow cover–soil union water–heat coupled movement model constructed in this paper is rational. [Copyright &y& Elsevier]

Abstract: In order to investigate the steady heat transfer characteristics of a porous media solar tower receiver developed in China, this paper applies the steady heat and mass transfer models of the porous media to solar receivers, chooses the preferable volume convection heat transfer coefficient model, solves these equations by using the numerical method, and analyzes the typical influences of the porosity, average particle diameter, air inlet velocity, and thickness on the temperature distribution. The following conclusions have been drawn: in the same position or relative position along the downstream, the bigger the average particle diameter is, the higher the solid matrix dimensionless temperature is, the higher the air dimensionless temperature is. The bigger the porosity is, the lower the solid matrix dimensionless temperature is, the bigger the porosity is, the higher the air dimensionless temperature is. The bigger the thickness is, the lower the solid matrix dimensionless temperature is, the higher the air dimensionless temperature is. In a certain depth, the bigger the air inlet velocity is, the higher the solid matrix dimensionless temperature is. After a certain depth, the bigger the air inlet velocity is, the lower the solid matrix dimensionless temperature is, and the bigger the air inlet velocity is, the higher the air dimensionless temperature is. The paper can provide a reference for this type of receiver design and reconstruction. [Copyright &y& Elsevier]

This method is based on the measured data of the efficiency of the heat pipe PV/T system under different solar radiation, and the typical meteorological year data, the system efficiency proposed in the existing literature, and the annual distribution of solar radiation in the region where the system located is comprehensively considered, then the annual average efficiency of heat pipe PV/T systems in different regions is obtained, and the annual heat collection and power generation of heat pipe PV/T systems are calculated and analyzed by this method. [Display omitted] • Efficiency of heat pipe PV/T systems under different radiation are tested. • The duration of solar radiation of different intensities in the typical year is statistically analyzed. • Efficiency differences of different radiations and solar radiation distribution are considered comprehensively. • An annual average efficiency evaluation method of heat pipe PV/T systems is proposed. As a passive heat transfer system, the heat pipe is becoming an important way to solve the problem of heat loss and heat accumulation in PV/T systems. However, the evaluation of the annual average efficiency of heat pipe PV/T systems in the existing studies does not consider the efficiency under different solar radiation and the difference in the annual solar radiation distribution in different regions. The purpose of this study is to propose a method for the annual average efficiency evaluation of heat pipe PV/T systems (AEHP method), which comprehensively considers the efficiency differences under different radiation and the distribution of solar radiation of different intensities in the typical year. The calculation results are more accurate, which will promote the reasonable evaluation and engineering application of heat pipe PV/T systems. Firstly, the dimensionless models of different radiation and their performance (photovoltaic efficiency, photothermal efficiency, and comprehensive efficiency) are established by experimental tests on the heat pipe PV/T system in this paper. Secondly, the frequencies and frequency of solar radiation in different intervals of the typical year in major cities of China are analyzed statistically, and the radiation frequency method is proposed. Thirdly, the average efficiencies of heat pipe PV/T systems in the existing literature are obtained by statistical analysis. Combined with the radiation frequency method, an annual average efficiency evaluation method of heat pipe PV/T systems (AEHP method) is proposed. The annual average efficiency of heat pipe PV/T systems in different regions is obtained. Finally, the annual heat collection and power generation of heat pipe PV/T systems are calculated based on the AEHP method, and provide a scientific and reasonable evaluation method for the promotion and application of heat pipe PV/T systems. [ABSTRACT FROM AUTHOR]

Phase change materials (PCMs) can be used for building envelope thermal management and for energy conservation because of their potential to absorb and release large amounts of heat with small wall temperature variations. In this paper, the heat transfer theory of a PCM board used for building envelopes is presented, together with a mathematical model based on the moving heat-source method. It was found that the model accurately predicted the position of the solid–liquid interface in time and space, comparing with the published data. Energy and mass efficiency (EME) was proposed to evaluate the energy efficiency of PCM boards in office buildings located in various climatic regions in China for cooling. The influences on EME of parameters, including melting temperature of PCM, PCM board thickness and the heat transfer coefficient of building envelope, were analyzed. The optimal melting temperatures of PCM board, which resulted in the peak EME, in office building were 24.1 °C in Shenyang, 25.0 °C in Kunming, 25.3 °C in Zhengzhou and 25.5 °C Changsha, respectively. The EME increased with the increasing heat transfer coefficient of building envelope. For the city of Changsha with higher outdoor air temperature, none of the PCM boards modeled contributed effectively. [ABSTRACT FROM AUTHOR]

The hybrid ground-coupled heat pump (HGCHP) systems with supplemental heat rejecter/supplier can effectively solve heat imbalance problems in the subsurface, and consequently improve the operation performance of the geothermal systems. For example, solar energy and/or industrial waste heat may be used as stable heat sources for underground heat storage in northern China with higher heating load, and cooling towers are installed to release heat into the air in southern China, where more cooling demand is needed. This paper reviews and discusses different HGCHP systems, which have been applied in China. And based on the heat transfer model of vertical borehole heat exchangers (BHE) for HGCHP systems, physical and mathematical models of multistage series circuits are developed to illustrate the heat transfer process of the underground thermal storage. A set of parameters, such as borehole spacing, heat recharging rate fractions and thermal properties of soils, which affect the thermal performance of the ground heat exchangers are analyzed, and the optimal solutions are discussed for engineering application. [ABSTRACT FROM AUTHOR]

In order to solve the practical problems on the utilization of a burning cave, such as overheated floor, uneven heat distribution, and serious heat lose, a hot water heating system integrated with a burning cave has been designed based on the principle of energy cascade utilization. However, there is no prediction and calculation method for designing this combined heating system. In this paper, through theoretical calculation, the response formula of time–temperature on the hot water heating system changed with the radiation intensity on biomass fuel combustion layer has been deduced and verified by experimental data. Besides, the impacts of the radiation temperature on fuel combustion layer, the height of fuel layer, pipe diameter, pipe spacing and water flow velocity on the heat transfer performance of this heating system have been respectively discussed. The thermal efficiency can be up to 39.3%. [ABSTRACT FROM AUTHOR]

The energy demand in China is rapidly growing, the development and applications of low energy technologies for green buildings have been paid much concern. The hollow block ventilated wall is proposed in this paper. According to the characteristic of the hollow part from up to down, the supply air passes through the cavity of the block, and then discharges to the outside after the heat exchange with the concrete hollow block, the cooling and heating requirements of envelope caused by outdoor environment can be partially removed; the building cooling/heating load can be greatly reduced or even eliminated. The Frequency-Domain Finite Difference (FDFD) model is established and the thermal performance analysis of hollow wall is carried out by using FDFD method in frequency domain. A CFD model is developed to simulate the thermal characteristics of this structure for reference for validating the FDFD model. The results demonstrate that the predictions of the FDFD and CFD models agree very well, and the FDFD model can provide accurate prediction. When the frequency varies, the frequency response of the heat flux is not obvious in low frequency region and is significant in high frequency. [ABSTRACT FROM AUTHOR]

The household-scale biogas system gains its popularity in rural China, and is now playing a prominent role in relieving energy shortages and reducing environmental pollution. A comprehensive review is performed for related environmental and ecological assessment studies. For an overall assessment of the biogas system, especially for its renewability and sustainability, an updated exergy methodology in terms of cosmic exergy is introduced in this paper, and is concretely illustrated by a case study to an integrated biogas engineering in Hubei, China. Associated with the fundamental universal scale of the cosmic-solar-terrestrial ecosystem, this new approach aggregates natural resources, economic inputs and environmental contamination on a common basis. Furthermore, a series of cosmic exergy based indicators are established to quantify the renewability and sustainability of the system. The integrated biogas engineering is proved to be with remarkable positive net ecological benefits, around twice that of the corresponding conventional production system. Near half of resource inputs in the integrated biogas system are found to be renewable. The renewability and sustainability of the biogas system turn out to be respectively double and six times those of the conventional system. The findings are fully supportive for policy makers in their action towards further progress of biogas project for sustainable development. [ABSTRACT FROM AUTHOR]

The aero-engine manufacturing industry is booming in China, while sustainability is neglected. For example, the grinding superalloy part uses a high-volume low-velocity flood delivery strategy for grinding cooling, which is harmful to health and the environment, consumes more resources and energy, emits more CO 2 and increases production costs. To achieve sustainability in the aero-engine manufacturing industry, it is worth considering eliminating coolant from the grinding to reduce the environmental impact and production cost. In this study, a novel oscillating heat pipe grinding wheel (OHP grinding wheel) is introduced to enhance the heat transfer in the eco-benign grinding process. The core concept is to design, fabricate particular oscillating heat pipes and position them in the grinding wheel so that the inside oscillating heat pipes transfer out the heat directly through the grinding wheel to avoid heat gathering, lower the grinding temperature, and suppress the thermal damages. Moreover, the use of harmful coolant can be diminished or even avoided, and an eco-benign grinding technology can therefore be achieved. Holistic sustainability analysis is then conducted in this paper. Compared with grinding by Non-OHP grinding wheel, the water-based coolant is avoided, the energy consumption is reduced by 26%–42%, and the carbon emission is reduced by 45%–56%. The OHP grinding wheel shows a great advantage in eco-benign grinding. • A novel oscillating heat pipe grinding wheel for eco-benign grinding is designed. • Carbon emission reduces 45%, production cost drops 41% by the proposed technology. • Energy consumption reduces 26%–42% by the proposed grinding wheel. • The proposed grinding wheel improves the material removal rate by 2.4 times. [ABSTRACT FROM AUTHOR]

Excessive water production from hydraulically fractured unconventional reservoirs is historically considered as burdensome liability in terms of costly treatment and disposal. However, this paper demonstrated produced water as a valuable asset, which is capable of producing geothermal energy, and it can actually help offset the operation costs for unconventional oil and gas producers. Harnessing geothermal energy of produced water for power generation from unconventional horizontal wells features significant advantages over traditional geothermal wells, especially in reducing capital expenditure and operational risks. This paper proposed a novel design of downhole power generation in horizontal wells by integration of thermoelectric technology with hydrocarbon production. In the design, we retrofit the horizontal wellbore to circulate cold water inside the tubing so that a cold temperature interface can be created. The produced fluids flow through the annulus of the tubing and casing to maintain hot temperature on the side of tubing. By attaching thermoelectric generators (TEG) on the outer surface of tubing, this retrofit will make it possible to capture subsurface in-situ geothermal energy of the produced fluid and directly transfer heat to electricity inside the horizontal wellbore. Furthermore, we also built the mathematical model to account for the heat conduction and convention in the wellbore and surrounding formation, which could accurately simulate the temperature distribution and power generation under variable operational conditions. Based on the model, we identified the key parameters with significant impact on power generation and established the well section criteria for best power generation performance. To discover the potential of power generation in horizontal wells, we conducted a case study in Daqing Oilfield in northeast China and compared the power generation performance with vertical well with same TVD and same power generation device installation. The results of case study indicated that horizontal well displayed exceeding power generation performance over vertical wells. In practice, this paper could contribute to enrich geothermal development methods and provide the guidelines for oil and gas producer to evaluate their horizontal assets and identify the opportunity to capitalize on geothermal power generation from horizontal wells. [ABSTRACT FROM AUTHOR]

Piston action can affect the thermal environment inside the tunnel by changing the air pressure and velocity. This is extremely unfavorable for tunnels in cold regions because it causes frost damage in cold season. Understanding the influence of piston action on the air temperature distribution inside the tunnel can help us determine the length and location of frost damage. In this paper, a heat transfer numerical model considering piston action is developed. And then, a high-speed railway tunnel in the northeast of China is taken as an example to explore the temperature distribution laws via computational fluid dynamic (CFD). Afterwards, the effects of air temperature outside the tunnel and train velocity on temperature distribution are analyzed. The results show that the piston action can accelerate the heat transfer between cold air outside and inside the tunnel, the anti-freezing length near tunnel entrance and exit must be extended based on the calculation result of existed empirical formula. Before the train enters the tunnel, the freezing length near tunnel entrance is 1158 m. After the train passing through the tunnel, the freezing length near tunnel entrance is between 1495 m and 1497 m when the air temperature outside the tunnel decreases from −1 °C to −15 °C. Under different train velocities (80 km/h, 130 km/h, 160 km/h, 200 km/h and 250 km/h), the freezing lengths near tunnel entrance are 1458 m, 1469 m, 1472 m, 1497 m, 1498 m and its near tunnel exit are 330 m, 342 m, 349 m, 356 m, 357 m, respectively. In the section of 50 m away from tunnel entrance, the air temperature near the train changes suddenly, while the air temperature far away from the train changes gently. After the train passing through the tunnel, the air temperature inside the tunnel is consistent to that outside the tunnel within a specific distance from entrance. This study provides a guideline and references for the structure design and the construction of anti-freezing measurements for the tunnels in cold regions. [ABSTRACT FROM AUTHOR]

Abstract: In cold region, precipitation, air temperature and snow cover significantly influenced soil water and heat transfer, and thus freezing–thawing processes of active soil layer. On the basic of physical processes of water and heat balances and their transfers in the snow covered soil, a water-heat coupling model for snow cover and its underlying soil layers was established in this paper. Numerical solution of the model was conducted by a full-implicit finite volume method. Observation data of snow cover depth, soil water content and active soil depth at two typical sites in the northeast of Three-River Source Region of China were selected for model calibration and validation. The results indicate that the model can capture soil freezing–thawing processes at the two sites. Simulated results reveal that variations of soil water content, soil temperature and soil freezing depth depend on climate conditions of air temperature, precipitation and snow cover as well. In comparison of the simulated results at two sites, we know that thick snow cover hinders temperature transfer from air to soil, resulting in prolonging the time lag between air and soil temperatures, decreasing variations of soil temperature and soil water content and reducing soil freezing depths of active soil. [Copyright &y& Elsevier]

Abstract: This paper develops an overall methodology for investigating the thermal and power behaviors of semi-transparent single-glazed photovoltaic window for office buildings in Hong Kong. In order to estimate its overall energy performance, this study is conducted in terms of total heat gain, output power and daylight illuminance. Three simulation models are established, including one-dimensional transient heat transfer model, power generation model and indoor daylight illuminance model. A typical office room reference is chosen as case study, and the weather data from 2003 to 2007 from the Hong Kong Observatory are used as the simulation inputs. By incorporating the simulation results, the overall energy performance can be evaluated in terms of electricity benefits corresponding to five orientations of the studied typical office. The priority of office orientation considering overall energy performance is: south-east, south, east, south-west and west. The findings show that thermal performance is the primary consideration of energy saving in the entire system whereas electricity consumption of artificial lighting is the secondary one. The overall annual electricity benefits are about 900 kWh and 1300 kWh for water-cooled and air-cooled air-conditioning systems respectively. The application of semi-transparent PV glazed window can not only produce clean energy, but also reduce building energy use by reducing the cooling load and electrical lighting requirements, which definitely benefits our environmental and economic aspects. [Copyright &y& Elsevier]

Abstract: A number of radiant heating/cooling systems have been applied in Mainland China in recent years for its improved thermal comfort and inherent energy saving potential. Because the systems require relatively higher temperatures for cooling and lower temperatures for heating, many natural low-grade energy sources can be directly or indirectly used. However, because of a lack of information about prior practical projects, a number of difficulties in design, construction and management of the systems have been encountered, and energy efficiency is not necessarily achieved in all situations. This paper reviews the practical applications in four major projects involving different building types located in different climatic cities and presents the associated considerations in system design. Other factors affecting the energy efficiency of the systems are identified, such as the spatial convection and radiation heat transfer processes in indoor environments and the envelope thermal properties. Further studies are needed to achieve system optimization and to realize the full energy saving potentials of radiant systems by developing analytical design methods and monitoring the actual energy use of such systems in completed projects. [Copyright &y& Elsevier]

Abstract: Evaporative cooling is an energy efficient and environmentally friendly air conditioning technology. Research and application of evaporative cooling in China have been very fruitful; however, they were little known to the world because most of works were published in Chinese. Therefore, this paper intends to present a comprehensive summary on them. The working principles and thermodynamic characteristics of different types of evaporative cooling, including direct, indirect and semi-indirect evaporative cooling, are first introduced. Experimental and theoretical research works on feasibility studies, performance test and optimization as well as heat and mass transfer analysis are then reviewed in detail. The feasibilities of evaporative cooling under different climates, efficiencies of various evaporative cooling equipment, and critical parameters and techniques for improving the efficiencies as well as numerical modeling of evaporative cooling processes are recalled. The typical systems and equipments of evaporative cooling adopted in China are reviewed in Part II. [Copyright &y& Elsevier]

Abstract: The use of groundwater for cooling and heating purposes is of interest from both the economical and the ecological perspective. The groundwater heat pump (GWHP) system utilizes groundwater as alternative renewable and clean energy source for space heating and/or cooling, withdraws water from a production well, passes it through a heat exchanger and discharges the water into an injection well. By utilizing the relatively stable temperature of groundwater, GWHP system can achieve a higher coefficient of performance. Due to the utilization of groundwater stored in the aquifer, the assessment of the hydraulic capacity of the aquifer based on numerical groundwater models is always needed for the optimum design and the efficient performance of GWHP. In this paper, numerical methods of underground heat-water transfer, energy balance method and thermal storage method were presented to calculate the capacity of unit area of shallow groundwater aquifer. The model results indicate that the numerical method, which is based on performance efficiency of GWHP, represents the behaviour of groundwater pumping/recharging processes, and serves better than energy balance method and thermal storage method, in addition it has been proven itself that this method has the advantages of energy saving and environmental protection. The calculated capacity is positively related to aquifer thickness. It is found that it is easy for ground water recharge in alluvial and pluvial fan located at the piedmont, while the calculated capacity is relatively smaller compared with that of south-east plain where it is not easy for groundwater recharge. [Copyright &y& Elsevier]

Abstract: Water wall design is a key issue for supercritical Circulating Fluidized Bed (CFB) boiler. On account of the good heat transfer performance, rifled tube is applied in the water wall design of a 600MW supercritical CFB boiler in China. In order to investigate the heat transfer and frictional characteristics of the rifled tube with vertical upward flow, an in-depth experiment was conducted in the range of pressure from 12 to 30MPa, mass flux from 230 to 1200kg/(m2 s), and inner wall heat flux from 130 to 720kW/m2. The wall temperature distribution and pressure drop in the rifled tube were obtained in the experiment. The normal, enhanced and deteriorated heat transfer characteristics were also captured. In this paper, the effects of pressure, inner wall heat flux and mass flux on heat transfer characteristics are analyzed, the heat transfer mechanism and the frictional resistance performance are discussed, and the corresponding empirical correlations are presented. The experimental results show that the rifled tube can effectively prevent the occurrence of Departure from Nucleate Boiling (DNB) and keep the tube wall temperature in a permissible range under the operating condition of supercritical CFB boiler. [Copyright &y& Elsevier]

Abstract: A cooperative study has been initiated at Xi''an Jiaotong University (XJTU) with Atomic Energy of Canada Limited (AECL) to develop a subchannel code ATHAS for preliminary analyses of flow and enthalpy distributions and cladding temperatures in CANDU fuel at super-critical water conditions. The code is applicable for transient and steady-state calculations. Then the paper uses the ATHAS code to analyze CANDU-SCWR which is operating at 25.0MPa pressure. The results show that the maximum cladding-surface temperature of CANFLEX bundle is 804.1°C, which is below the limit of design, and it is appropriate for use in the CANDU super-critical water-cooled reactor (SCWR) based on heat-transfer analysis. [Copyright &y& Elsevier]

Abstract: Lightweight envelopes are widely used in modern buildings but they lack sufficient thermal capacity for passive solar utilization. An attractive solution to increase the building thermal capacity is to incorporate phase change material (PCM) into the building envelope. In this paper, a simplified theoretical model is established to optimize an interior PCM for energy storage in a lightweight passive solar room. Analytical equations are presented to calculate the optimal phase change temperature and the total amount of latent heat capacity and to estimate the benefit of the interior PCM for energy storage. Further, as an example, the analytical optimization is applied to the interior PCM panels in a direct-gain room with realistic outdoor climatic conditions of Beijing. The analytical results agree well with the numerical results. The analytical results show that: (1) the optimal phase change temperature depends on the average indoor air temperature and the radiation absorbed by the PCM panels; (2) the interior PCM has little effect on average indoor air temperature; and (3) the amplitude of the indoor air temperature fluctuation depends on the product of surface heat transfer coefficient h in and area A of the PCM panels in a lightweight passive solar room. [Copyright &y& Elsevier]

Clean district heating systems are needed in large cities, especially in Northern China. This paper presents a low carbon district heating system that features a low return water temperature, use of low grade waste heat as the main heat source, long distance heat transmission with a large temperature difference, distributed peak heating load addition by natural gas and heat-power decoupling with heat pump and thermal storage. This Low carbon district heating 2025 system is suitable for large cities, large waste heat sources, high heating densities and the utilization of using existing large heating networks in almost all the cities of Northern China. These clean heating systems in Chinese cities have great potential to reduce energy use, reduce emissions and improve the district heating system economics. [Display omitted] • Low carbon district heating 2025 system is designed for large cities, large waste heat sources, high heating densities. • It describes a district heating system which uses low-grade thermal energy. • It features with a large temperature difference for heat transmission. • It solves heat-power decoupling with heat pump and thermal storage. • It reduces the energy consumption and emissions by 80% compared to coal boilers. [ABSTRACT FROM AUTHOR]

One of the most important requirements in the design of pressurized water reactor (PWR) is to avoid the occurrence of critical heat flux (CHF). The design criteria for PWR specify that they must be operated at a certain percentage below CHF at all times and locations so as to the cladding temperature of fuel element at safe values. So in the process of safety assessment, CHF is one of important thermal-hydraulic parameters limiting the available power, whose size directly affects safety and economy of PWR nuclear power plant. This paper deals with a summary of experimental research progress on CHF of Chinese PWR. It mainly presents CHF experimental researches of Φ10 fuel assembly, CHF experimental researches of standard fuel assembly, and CHF experimental progress of non-uniform heated rod bundles. It should be emphasized that it also presents experimental research programs on CHF of Chinese advanced fuel assembly with self-reliance copyright. All CHF data obtained will be used for design improvement of Chinese PWR and R&D program of New Generation 1000 MWe PWR. [Copyright &y& Elsevier]

• CFETR central solenoid model coil heat treatment was successfully completed. • The calculation and simulation heat transfer model of Nb 3 Sn coil heat treatment is established. • The design of the inner cover improves the temperature uniformity of the Nb 3 Sn coil heat treatment. • To provide experience for other large superconducting coil heat treatment in China. The heat treatment of Nb 3 Sn coils of China Fusion Engineering Test Reactor (CFETR) central solenoid model coil (CSMC) has been completed at the Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP). The brittle A15 phase material requires coil winding prior formation of the superconducting material, and the technology of "wind and react" has been used to manufacture Nb 3 Sn coil. The Nb 3 Sn coils were heat-treated under the argon atmosphere and the heat treatment was successful. Since the critical properties of Nb 3 Sn strongly depend on the heat treatment temperature, especially the uniformity of temperature, it is necessary to analyze the detailed temperature change process during the heat treatment. During the heat treatment, several thermocouples were arranged on the coil surface for temperature monitoring. At the same time, the heat transfer process of heat treatment and the distribution of the coil temperature field is theoretically analyzed and simulated. The uniformity of heat treatment temperature meets the requirements. This paper mainly presents the heat transfer analysis, heat treatment process, and numerical simulations during heat treatment. [ABSTRACT FROM AUTHOR]

In this paper, the development process of sub-channel code was described in detail, and some widely approved sub-channel codes were comprehensively reviewed, such as COBRA, FLICA, CORTH, and ASSERT applying to the commercial nuclear power plants. Moreover, the development of conservation equations and the corresponding constitutive equations were introduced, including the heat conduction model, the heat transfer model, the mixing model, and CHF (Critical Heat Flux) model. Finally, CORTH-V2.0 sub-channel code was introduced, which was autonomously developed by Nuclear Power Institute of China (NPIC) and served for ACP series PWR (Pressurized Water Reactor) as well as CF series fuel assembly. • The comprehensive evolution process of COBRA series sub-channel codes are reviewed in detail, and other typical sub-channel codes are introduced. • The constitutive model development of sub-channel code is analyzed. • The independently developed sub-channel code of CORTH-V2.0 belonging to NPIC is introduced. [ABSTRACT FROM AUTHOR]

Recently, the structural insulated panels (SIPs) with the wood-based surfacing materials are developed in housing industry to increase the thermal efficiency of the wall system. In order to integrate the waterproof feature into SIPs, a newly designed GFRP reinforced squared tube sandwich panel (GSTPs) is introduced, where the Glass fibre reinforced polymers (GFRP) is utilized as surface material and the core is reinforced by the GFRP square tube. This paper focused on the thermal insulation performance of GSTPs. Both experimental, theoretical and numerical methods are employed to study their thermal insulation performance as roof panels. More specifically, the thermal conductivity of GFPR with three different core materials, including glass wool, Extruded polystyrene (XPS) and Polyurethane (PU) in the SIP, was first measured by hot plate apparatus (HPA) in the steady-state heat transfer tests. Then, the heat transfer coefficients of three type of GSTPs with above mentioned core materials are measured by guarding heat box (GHB) test. The theoretical and finite element (FE) method based numerical studies applied to conduct the heat transfer analyses on those SIPs. The accuracies of the theoretical and numerical studies are verified by comparing the obtained heat transfer coefficients with those from the experimental tests. The results from the present study could provide a good reference to the selection of the suitable panel thickness and core materials for different thermal regions in China. [ABSTRACT FROM AUTHOR]

Groundwater heat pump (GWHP) systems are central heating and cooling systems that utilize groundwater heat. With the rapid development of this technology in China, it has become imperative to study the changes in the ground environment, including the flow features, heat transfer characteristics and clogging caused by long-term recharge, during the operation of GWHP systems. In this paper, a mathematical model considering the effect of particle deposition was proposed to describe a GWHP system based on the typical geological and hydrogeological conditions (i.e., a dual-structure strata) in Wuhan, China. During research on a GWHP engineering project in the Baibuting Garden community, four groundwater flow conditions (including no flow, forward flow, reverse flow and cross flow) and two typical flow modes (continuous and flushing modes) were considered. The groundwater temperature and flow rate were measured through measuring wells, and a comparison between theoretical and actual values shows that this model can provide an easy yet effective way to describe GWHP engineering. The seepage and temperature fields both display periodic trends under the continuous flow mode and can be significantly affected by well flushing. The central area is marginally influenced by groundwater flow when compared with the surrounding areas; for instance, the temperature fluctuation at MW3 can reach 8.2 °C, while the fluctuation reaches 2.9 °C at MW1. Particle deposition can affect the parameters of the ground environment; we find considerable correspondence between the concentration of deposited particles and the porosity. Moreover, both the concentration of deposited particles and the porosity change by a large margin after flushing, especially in regions around pumping wells (the concentration of deposited particles can fluctuate by 108 g/L, and the porosity can change by 0.055). [ABSTRACT FROM AUTHOR]