井水温观测分析中的水-热动力学研究综述

从井水温动态影响因素、井水温对动力加载的响应机理、水-热动力学理论模型三方面阐述了井水温研究进展。高精度数字化观测技术,为井水温的科学研究提供可靠、有效的数据支持。补给源和水动力作用是影响井水温动态变化的两大因素,补给源决定了井-含水层系统温度的垂直分布曲线的形态,水动力作用决定了含水层地下水补给量的多少和地下水流速的快慢,从而影响井-含水层系统温度变化的大小,而动力加载作用影响井-含水层系统内部的水流流动速度,改变水温变化情况。通过对井水温动态影响因素与水-热动力学形成机理研究的总结,有助于厘清井水温动态和含水层的关系,为井水温动态的定量分析和机理解释提供重要的研究思路。

冷水源井水温固体潮现象及其机理研究——以黄村井为例

该文对黄村冷水源井的水温固体潮现象进行了观测研究,初步解释了冷水源井的水温固体潮汐的形成机理.通过对黄村观测井进行水温梯度的详细观测及不同深度水温的对比观测研究,得到了黄村井水温潮汐现象的观测结果:(1)黄村冷水源井的水温固体潮的相位与水位的相位是相反的;(2)黄村井水温梯度曲线呈下凹型,特别是在含水层及受含水层进出水影响较大的附近区域下凹程度大,且随着与含水层底板距离逐渐变大,下凹程度也变小;(3)水温传感器的观测值与含水层观测距离存在一定的规律性:距离含水层越远,水温潮汐差越小,直至潮汐变化消失.这说明冷水源井与热水井的水温潮汐现象是不同的,前者是吸热过程,后者是放热过程,由此造成二者水-热动力学特征的不同.

Non-isothermal thermal decomposition kinetics of high iron gibbsite ore based on Popescu method

The thermal decomposition kinetics of high iron gibbsite ore was investigated under non-isothermal conditions.Popescu method was applied to analyzing the thermal decomposition mechanism.The results show that the most probable thermal decomposition mechanism is the three-dimensional diffusion model of Jander equation,and the mechanism code is D3.The activation energy and pre-exponential factor for thermal decomposition of high iron gibbsite ore calculated by the Popescu method are 75.36 kJ/mol and 1.51×10-5 s-（-1）,respectively.The correctness of the obtained mechanism function is validated by the activation energy acquired by the iso-conversional method.Popescu method is a rational and reliable method for the analysis of the thermal decomposition mechanism of high iron gibbsite ore.

Kinetic Study of Hydrothermal Stripping from Iron-Loaded Organic Phase

The iron-loaded organic phase of naphthenic acid-isooctyl alcohol-kerosene was prepared, and the process kinetics of hydrothermal stripping of iron from the phase was studied. Several factors affecting hydrothermal stripping, such as the polymer of naphthenic acid, initial concentrations of iron and naphthenic acid, temperature and agitation time, were investigated, and based on experimental results and theoretical analysis, two kinetic models were established.The stripping rate equation suggests that the hydrothermal stripping process activation energy is 96.4 kJ·mol-1 and the stripping is controlled by hydrolysis of naphthenic complex of iron. The values calculated by the stripping fraction equation comparatively accord with the experimental data.

Kinetic-Thermodynamic Analysis of the Reactive Distillation Process of the Cyclohexene Hydration Using the Zeolite Catalyst

Reactive distillation could be utilized to produce cyclohexanol through the cyclohexene hydration. By means of highly active zeolite catalyst HZSM-5, the kinetic-thermodynamic analysis of this reactive distillation has been carried out to get the characteristics of the reactive distillation. Results from kinetic and thermodynamic analysis indicate that the optimal pressure of this reactive distillation process should be set to higher pressure such as 0.3 or 0.4 MPa. To avoid the recovery of cyclohexanol at the top of the column, an unreactive section should be allocated at the upper column. In addition, the inert component benzene is more unfavorable to the reactive distillation process in comparison with the inert cyclohexane.

Thermal Dehydration Kinetics of Gypsum and Borogypsum under Non-isothermal Conditions

Thermal dehydration of gypsum and borogypsum was investigated under nonisothermal conditions in air by using simultaneous thermogravimetric-differential thermal analyzer. Nonisothermal experiments were carried out at various linear heating rates. Kinetics of dehydration in the temperature range of 373-503 K were evaluated from the DTA (differential thermal analysis)-TGA (thermogravimetric analysis) data by means of Coats-Redfern,Kissinger and Doyle Equations. Values of the activation energy and the pre-exponential factor of the dehydration were calculated. The results of thermal experiments and kinetic parameters indicated that borogypsum is similar to gypsum from dehydration mechanism point of view although it consists of boron and small amount of alkali metal oxides.

Prediction of Structure-H Gas Hydrate Formation Conditions for Reservoir Fluids

In this work, a thermodynamic model is developed for prediction of structure H hydrate formation. The model combines the Peng-Robinson equation of state for the vapor, liquid and aqueous phases with the extended Ng-Robinson hydrate model for gas hydrate formation of all three structures. The parameters of 14 structure- H hydrate formers are determined based on the experimental data of structure-H hydrates in the literature. The expression of fugacity of water in the empty hydrate phase is correlated for calculating structure-H hydrate formation conditions in the absence of free water. The model is tested by predicting hydrate formation conditions of a number of structure-H hydrate forming systems which are in good agreement with the experimental data. The proposed model is also applied to the prediction of hydrate formation conditions for various reservoir fluids such as natural gas and gas condensate.

Research status of soil frost-heave theory and frost-heave prediction models

Soil frost heaving is a complex physical, mechanical, and chemical synthesis process. This paper summarizes the frost-heaving theory over half a century, including the capillary theory, the frozen-fringe theory, and those achievements recently made by scholars. In this paper, we also discus researching achievements of the soil-prediction model during the past 40 years, including the water-dynamics model, the rigid-ice model, the segregation-potential model, and the thermo-dynamic model. This summary and discussion will enable readers to understand the latest direction of research; it also summarizes the development of frost-heave prediction models and their advantages and shortcomings.

A Revised CFB Wall-to-suspension Heat Transfer Model

Based on the Cluster Renewal Model of the particle motion in a CFB riser, a revised heat transfer model is developed, which introduces the latest research results of the hydrodynamics of the suspension flow in CFB. This model divides the heat transfer into two parts, which are due to the transient heat conduction by the covered clusters and the convection between the uncovered wall and the dispersed phase. Radiation at high temperature is regarded as being additive. The fraction of the covered wall by clusters is revised by a new formula, which is a function of the operating condition and the particle properties. The radiation between the dispersed phase and the uncovered wall includes not only the direct radiation to the uncovered wall, but also the radiation to the clusters and then reflected to the uncovered wall. Calculation was carried out for the CFB heat transfer model. The results were compared with the published typical experimental data of other researchers and showed a good agreement between them.

Three Dimensional Numerical Simulation of Convection-Condensation of Vapor with High Concentration Air in Tube with Inserts

A three-dimensional numerical model is presented for studying the convection-condensation of mixture with vapor in a tube with edgefold-twisted-tape inserts under transition flow.According to the diffusion layer theory and laminar species transport,a condensation model with user defined function is proposed and compared with heat and mass transfer analogy and experimental test.With the condensation model,the influences of gap width and op-erating parameters on thermal-hydrodynamics performance are simulated.As the gap width increases,convection and condensation heat transfer increase initially and then decrease,while convection heat transfer increases sharply and then decreases slightly.Increasing vapor fraction has a significant effect on condensation heat transfer but it has little effect on convective heat transfer.With the increase of inner wall temperature both convection and condensa-tion heat transfer all decrease and the ratio of condensation to total heat decrease dramatically.Increases inlet tem-perature mainly affects convection heat transfer.

Thermal dehydration kinetic mechanism of Mn_(1.8)Co_(0.1)Mg_(0.1)P_2O_7·2H_2O using Málek's equations and thermodynamic functions determination

Mn1.8Co0.1Mg0.1P2O7·2H2O was synthesized via hydrothermal method and the thermal dehydration product was confirmed to be Mn1.8Co0.1Mg0.1P2O7.The thermogravimetry/differential thermogravimetry/differential thermal analysis,Fourier transform infrared,atomic absorption spectrophotometry,X-ray diffraction and scanning electron microscopy techniques were employed for sample characterization.Non-isothermal kinetics was studied under air atmosphere at four heating rates and the single thermal dehydration process was observed.Iterative Kissinger-Akahira-Sunose equation was used to calculate the apparent activation energy Eαvalues.Dehydration process was confirmed to be a single-step kinetic process with the unique kinetic triplets.Málek’s equations were used to determine the kinetic model f（α）and pre-exponential factor A.？esták-Berggren model was suggested to be the mechanism function for the dehydration process.The best fit led to the kinetic triplets of Eα=（79.97±6.51）k J/mol,ln A=16.83 and f（α）=α^0.520（1-α）^1.255（αis the extent of conversion）.The thermodynamic functions of activation were calculated using activated complex theory together with A value.

Thermal Analysis of Composite Cements

The hydration of cement compounds gives hydrated compounds, which allow linking together, the different particles and aggregate of cement, and gives the concrete the required qualities. The dynamics of hydration reactions will depend on many factors, such as the fineness of cement, the ratio w/c during hydration, temperature, mixing technique, and the presence of additives in blended cement, as pozzolan, tuff and slag from blast furnaces. We studied the thermal and kinetic reactions of Portland cement hydration, and its variants with different additions using a differential scanning calorimetric analysis. The parameters from these models of curves allow us to evaluate the enthalpies, and the degree of progression of this blended cement, and finally determine their activation energies. We can say that the hydration of Portland cement is due to a series of reactions as （ C3S,C2S,C3A and C4AF reactions with water） and each of them, has its own kinetic, the experimental measurement of the heat of hydration, allows us to represent the overall kinetics of these reactions values of activation energy, they are therefore apparent and global energy. In our experiments, significant differences in these physicochemical parameters were observed, depending on the additive used.

Numerical investigation of optimal geometry parameters for ejectors of premixed burner

An ejector of low NO~ burner was designed for a gas instantaneous water heater in this work. The flowing and mixing process of the ejector was investigated by computational fluid dynamics （CFD） approach. A comprehensive study was conducted to understand the effects of the geometrical parameters on the static pressure of air and methane, and mole fraction uniformity of methane at the outlet of ejector. The distribution chamber was applied to balance the pressure and improve the mixing process of methane and air in front of the fire hole. A distribution orifice plate with seven distribution orifices was introduced at the outlet of the ejector to improve the flow organization. It is found that the nozzle exit position of 5 mm and nozzle diameter d 〉1.3 mm should be used to improve the flow organization and realize the well premixed combustion for this designed ejector.

Dissolution-filling mechanism of atmospheric precipitation controlled by both thermodynamics and kinetics

Affected by structural uplift, the Ordovician carbonate rockbed in the Tarim Basin, China, was exposed to dissolution and reformation of atmospheric precipitation many times, and formed a large quantity of karst caves serving as hydrocarbon reser- voir. However, drilling in Tahe area showed that many large karst caves, small pores and fractures are filled by calcite, result- ing in decrease in their reservoir ability. Calcite filled in the karst caves has very light oxygen isotopic composition and STSr/S（＇Sr ratio. Its c^OpDB ranges from -21.2%o to 13.3%o with the average of -16.3%e and its 87Sr/86Nr ratio ranges from 0.709561 to 0.710070 with the average of 0.709843. The isotope composition showed that calcite is related to atmospheric precipitation. Theoretic analyses indicated that the dissolving and filling actions of the precipitation on carbonate rocks are controlled by both thermodynamic and kinetic mechanisms. Among them, the thermodynamic factor determines that the pre- cipitation during its flow from the earth surface downward plays important roles on carbonate rocks from dissolution to satura- tion, further sedimentation, and finally filling. In other words, the depth of the karstification development is not unrestricted, but limited by the precipitation beneath the earth surface. On the other hand, the kinetic factor controls the intensity, depth, and breadth of the karstification development, that is, the karstification is also affected by topographic, geomorphologic, climatic factors, the degree of fracture or fault, etc. Therefore, subject to their joint effects, the karstification of the precipitation on the Ordovician carbonate rocks occurs only within a certain depth （most about 200 m） under the unconformity surface, deeper than which carbonate minerals begin to sedimentate and fill the karst caves that were formed previously.

Energy budget of cosmological first-order phase transition in FLRW background

We study the hydrodynamics of bubble expansion in cosmological first-order phase transition in the Fdedmann-LemMtre- Robertson-Walker （FLRW） background with probe limit. Different from previous studies for fast first-order phase transition in flat background, we find that, for slow first-order phase transition in FLRW background with a given peculiar velocity of the bubble wall, the efficiency factor of energy transfer into bulk motion of thermal fluid is significantly reduced, thus decreasing the previously-thought dominated contribution from sound wave to the stochastic gravitational-wave background.

Exploration of uniform heat flux on the flow and heat transportation of ferrofluids along a smooth plate： Comparative investigation

The paper is devoted to a new extension in Gegenbauer wavelet method （GWM） to investigate the transfer of heat and MHD boundary-layer flow of ferrofluids beside a flat plate with velocity slip. A homogenous model study is conducted in which we assumed the heat transfer and forced convective flow of ferrofluids along a flat plate with a uniform wall heat flux. In the direction of transverse to plate, a magnetic field is imposed. Three various magnetic nanoparticle types including Mn-ZnFe204, CoFe204, Fe3O4 are incorporated inside the base fluid. Two types of base fluids （water and kerosene） with bad thermal conductivity as compared to nanoparticles of solid magnetic have been assumed. The mathematical model is tackled via modified Gegenbauer wavelet method （MGWM）. A simulation is accomplished for individual ferrofluid mixture by assuming the prevailing impacts of uniform and slip heat fluxes. The variation of heat transfers and skin friction were also observed at the surface of the plate and we analyzed the better heat transfer for every mixture. Kerosene-based magnetite （Fe304） delivers the better rate of heat transfer at wall due to its association with the kerosene-based Mn-Zn and cobalt ferrites. The slip velocity and magnetic field effects on the temperature, dimensionless velocity, rate of heat transfer and skin friction are examined for various magnetic nanoparticles inside the kerosene oil and water. We observed that the primary influence of magnetic field reduces the dimensionless surface temperature and accelerates the dimensionless velocity as compared to the hydrodynamic case, thus enhancing the rate of heat transfer and skin friction ferrofluids. Moreover, a detailed evaluation of outcomes obtained by MGWM, already published work and numerical RK-4 were found to be in excellent agreement. The error and convergence analysis are presented. Comparison of results,graphical plots, error and convergence analysis reveal the appropriateness of proposed method. The proposed algorithm can be extended for other nonlinear problems.