天然硫化物矿物对地球深部热能的热电转化效应研究

金属硫化物半导体矿物在地壳中分布广泛,其中一些禁带宽度较窄的硫化物矿物,如黄铁矿、黄铜矿和斑铜矿等,在地热梯度下产生的天然热电势可将地球内部热能转化为电能。本文选取黄铁矿、磁黄铁矿、方铅矿、黄铜矿、斑铜矿以及斑铜矿-赤铁矿-辉铜矿集合体等天然硫化物矿物样品,研究了其热电特性。研究结果表明,300～700K下,除磁黄铁矿具有低塞贝克系数和超高电导率而表现出金属导体的电输运行为外,黄铁矿和黄铜矿为n型半导体,斑铜矿和斑铜矿-赤铁矿-辉铜矿集合体为p型半导体,具有150～500μV/K的显著塞贝克系数和5～95 S/cm的电导率,说明样品在地热梯度下具有产生显著热电效应的能力。根据激光闪射法测得的热扩散率以及样品的理论比热、密度计算热导率,斑铜矿及硫化物矿物集合体样品表现出小于1 W/(m·K)的低热导率,说明样品在局部热源影响下可形成较大温差。根据热电基本理论和地热梯度构建天然热电效应模型,对硫化物半导体矿物集合体产生的天然热电势、额外地表电流密度及热电转换效率进行了模拟计算得出经验公式,发现硫化物半导体矿物在300～650 K条件下能产生100 m V左右的天然热电势,产生的最大热电转化率可达4‰,且可以通过偶极电流源模型计算矿物体产生的额外地表电流密度。研究认为硫化物半导体矿物可能作为天然热电转换介质深刻影响地球内部能量的转化与传递过程。     

Identification of sources of ultrahigh energy cosmic rays

The arrival directions of extensive air showers with energies 4×10¹⁹<E≤3×10²⁰ eV detected by the AGASA, Yakutsk, Haverah Park, and Fly’s Eye arrays are analyzed in order to identify possible sources of cosmic rays with these energies. We searched for active galactic nuclei, radio galaxies, and X-ray pulsars within 3-error boxes around the shower-arrival directions and calculated the probabilities of objects being in the 3 error boxes by chance. These probabilities are small in the case of Seyfert galaxies with redshifts z<0.01 and BL Lac objects, corresponding to P>3σ (σ is the parameter of Gaussian distribution). The Seyfert galaxies are characterized by moderate luminosities (L<10⁴⁶ erg/s) and weak radio and X-ray emission. We also analyzed gamma-ray emission at energies E>10¹⁴ eV recorded by the Bolivian and Tian Shan arrays. The source identifications suggest that the gamma rays could have been produced in interactions of cosmic rays with the microwave background radiation and subsequent electromagnetic cascades in intergalactic space. We estimate the strength of intergalactic magnetic fields outside galaxy clusters to be B≤8.7×10^?10 G.     

Laboratory thermal conversion of sedimentary lipids to kerogen-like matter

A laboratory heating experiment was conducted in an attempt to evaluate the possible role of lipids as precursors for petroleum hydrocarbons. Lipids were extracted from a Recent lake sediment (Lake Haruna, Japan), and heated under N₂ atmosphere, at 125–370°C, for 1–7 days. A significant amount of lipids was polymerized to kerogen-like matter (lipid-derived kerogen) at the low temperature of 175°C for 1 day. The polymerization follows first-order kinetics, and the half life of lipids is calculated to be 10⁴–10⁵ yr at 0–30°C. The lipid-derived kerogen generated a significant amount (62 mg/g) of n-alkanes (C₁₄–C₃₆) on heating at 350°C for 1 day.The results indicate a possible occurrence of lower temperature thermal polymerization of lipids in a relatively early stage of diagenesis as one of the formation pathways of kerogen with high hydrocarbon producing potential.     

Determination of ground thermal properties for energy piles by thermal response tests

Thermal properties of ground heat exchanger (GHE) such as effective thermal conductivity and borehole thermal resistance are commonly measured in the field by thermal response tests (TRTs). TRT has been proved to be a consolidated method to determine thermal properties of traditional borehole heat exchangers (BHEs). However, there is still lack of data for adopting TRT on energy piles with often a large diameter and deficiency in validation of TRT results with geological materials. In this study, ground thermal properties for typical configured GHEs of energy piles are investigated. Three TRTs are conducted and the obtained results are analyzed. Effective thermal conductivity, λ_eff, of the ground derived by following the traditional linear source model shows large deviation as compared to the thermal conductivity of the geological materials. In order to determine λ_eff properly, the linear source model is modified and an equivalent radius, r_eq, of energy piles is considered. The λ_eff estimated by the modified model shows a good agreement with thermal conductivity of the in situ geological materials. In addition, there has been no obvious correlation between borehole thermal resistances and thermal efficiency due to heat transport of energy piles that depends not only by borehole thermal resistance but also by the pile’s diameter and ground conditions. The findings drawn from this study indicate that the modified model is reasonable and useful in determining thermal properties of energy piles.     

The role of thermal springs in trace element contamination in NW Iran

In this study, the size of the metal pools and the fluxes between the pools of eight trace metals （Cu, Ni, Zn, Pb, Cd, A1, Mn, Fe） were measured in a small, oligotrophic, dilute lake located in south-central Ontario, Canada. The lake （Plastic Lake） and its catchment have been affected by acid deposition and have been studied since 1979. Limited data were collected for a number of other elements including, V, Cr, Co, As, Rb, Sr, T1, Bi, U and Se and isotope budgets for a few metals （e.g. Pb） were determined. Measurements were available for the sediments, the lake itself, and the wetland and upland portions of the catchment, and thus individual budgets for all compartments could be constructed. These budgets provided information regarding the relative importance of atmospheric inputs versus mobilization from lithogenic sources. In addition, the effects of acid deposition and dissolved organic matter （DOM） on contaminant storage and transfer were investigated. Results indicate that elements such as Pb and V have largely an atmospheric source whereas Cu, Zn, A1 and Fe are primarily derived from the catchment.     

地下含水层储能两阶段热量运移数值模型研究

为了简单而准确地预测地下含水层储能情况,考虑了地下含水层储能过程时间跨度大、储能保温分阶段的实际特点,分析了地下含水层流动和换热模型物理参数的对比特点,以热平衡和热扩散原理为基础,建立分成两个连续阶段的地下含水层储能数值计算模型.模型求解中,采用控制容积法,以全隐格式进行热扩散方程的离散化,然后应用Jacobi方法迭代求解,模拟结果和实际观测数据吻合很好.该模型还分析了含水层储能循环采灌过程中抽出储能水的温度变化的一般特点.     

Effect of thermal treatment on physical and mechanical properties of sandstone for thermal energy storage: a comprehensive experimental study

Acta Geotechnica - Natural rock is considered a solution for thermal energy storage (TES). comprehensive understanding of the effect of high temperature on the physical and mechanical properties of...     

深层含水层地下储热技术的发展现状与展望

深层含水层储热是一种利用深度>500 m的深层含水层作为储热介质的储热技术,储热对象通常为50~150 ℃的热水。它通过地下水井从深层含水层中抽取和灌入地下水,实现热能储存和回收。深层含水层储热技术是弥补能源供需时空分布的不平衡,综合利用多种可再生能源,实现节能减排的有效途径,是国内外研究的前沿和热点。文中首先阐述了深层含水层储热系统在世界范围内的历史发展,归纳储热系统的热工性能,在总结前人研究工作的基础上分析影响其热回收效率的关键参数,并对各个参数对热回收效率的敏感性做了综述。在此基础上,本文还讨论了限制深层含水层储热系统发展的技术瓶颈,并针对系统的经济效益和市场潜力做了预测和展望。     

模糊综合评判法分析地震滑坡启程能量转换

地震滑坡启程能量转化分析对于后期滑坡动力学研究极为重要,因其影响因素较多,具有模糊性,目前还没有准确的定量计算公式。模糊综合评判法分析模糊问题具有明显的优势,能够综合考虑各种因素给出总体评价。选取地震加速度、岩体结构类型、控制性结构面特征、岩体完整程度、地层岩性、地下水、不利结构面与临空面的夹角7个因素作为地震滑坡启程剧动能量转换大小划分的主要因素,详细分析各个因素对能量转化的影响。采用逻辑分区法确定隶属函数,应用模糊层次分析法（FAHP）确定各因素的权重。在此基础上,运用模糊数学综合评判方法得出能量转化率等级,半定量地确定能量转化率大小。以东河口地震滑坡为例,应用模糊综合评判法对其启程能量转换分析结果客观合理,表明该方法是科学可行的,在同类理论研究中可以借鉴。     

西藏日多温泉水化学特征及其物质来源

热泉水的水化学特征包含其形成过程中地质、构造、断裂、蚀变以及环境变化等多种信息,是研究地热流体形成和物质来源最基本和最重要的特征之一。西藏日多温泉发育于古新统典中组（E1d）和下白垩统林布宗组（K1l）地层。水化学特征显示:日多温泉地下热储温度为97.5 ℃~110.1 ℃之间,pH值为中性,水化学类型为SO4·HCO3-Na型,阳离子以Na+、Ca2+、K+为主,阴离子以Cl-、SO42-、HCO3-为主,并富含HBO2、H2SiO3、F、Li、Sr、Cs、As,矿化度介于1 162 mg/L～1 245 mg/L之间,符合理（医）疗热矿泉水水质标准。温泉水富含多种矿物组分的特征,与温泉水循环深度大、地下滞留时间较长（推测大于48 a）、地下热水与火山岩水-岩作用强烈有直接关系。综合研究热矿水的水化学特征,有助于更好地认识热泉水的形成过程,为热泉资源的开发利用和保护提供科学依据。      

Determination of the sources and circulation paths of thermal fluids: the Abano region,northern Italy

Water samples from natural springs and artesian wells in the Abano region of northern Italy are characterized by anomalous temperatures and compositions. Concentrations of major components and oxygen isotopes in samples of these fluids have been interpreted in the context of the regional geologic environment, circulation of groundwaters, and reactions between rocks and circulating groundwaters. These considerations define sourceregions and pathlines of the groundwaters.Circulation of fluids in the Abano region is interpreted to be the result of meteoric water infiltration into outcrops of Permian and Mesozoic aquifers in the pre-Alps, which lie north of the Abano region. These aquifers have southerly dips and, therefore, extend under the Abano region at depths between 0.5 and 2.5 km. This aquifer geometry is conducive to forced convection both of aqueous ions derived from the evaporate, limestone and dolomite bearing formations, and of thermal energy along flow paths which extend from the outcrops in the sourceregions to depths of 2 km below the Abano region and upward along high angle faults to thermal springs. Local variation in compositions of water samples is consistent with the mixing of local meteoric waters and formation fluids that were ultimately derived from Alpine sources.     

Some features of possible sources of the energy release in solar flares

Magnetic field singularities detected earlier as the self-intersection points of the F = 0 curves/surfaces are studied (where F is a certain differential factor calculated in the reference frame of the magnetic field at the given point); these singularities can be considered to be sources of the energy release in solar flares. Two types of such singularities, called transition points (TPs), have been found: the first type (TP1) corresponds to an intersection of the same type of components (terms) of the divergence of the magnetic field, and the second type (TP2) to the intersection of dissimilar components. There are some discontinuous spatial processes at these singularities, which produce jumps in the components of the divergence of the magnetic field (and their signs). TP2 singularities should result in much stronger effects than those resulting from TP1 singularities, which should give rise to the most powerful solar flares. The singularities studied are also compared with the null point of the magnetic field, when it exists. In particular, a model magnetic field containing a null point is considered. It is shown that the TP singularities do not coincide with the null point, but can be located in its vicinity; in the case considered, the TP1 singularity is located fairly close to the null point.     

Analysis of recovery efficiency in high-temperature aquifer thermal energy storage: a Rayleigh-based method

High-temperature aquifer thermal energy storage (HT-ATES) is an important technique for energy conservation. A controlling factor for the economic feasibility of HT-ATES is the recovery efficiency. Due to the effects of density-driven flow (free convection), HT-ATES systems applied in permeable aquifers typically have lower recovery efficiencies than conventional (low-temperature) ATES systems. For a reliable estimation of the recovery efficiency it is, therefore, important to take the effect of density-driven flow into account. A numerical evaluation of the prime factors influencing the recovery efficiency of HT-ATES systems is presented. Sensitivity runs evaluating the effects of aquifer properties, as well as operational variables, were performed to deduce the most important factors that control the recovery efficiency. A correlation was found between the dimensionless Rayleigh number (a measure of the relative strength of free convection) and the calculated recovery efficiencies. Based on a modified Rayleigh number, two simple analytical solutions are proposed to calculate the recovery efficiency, each one covering a different range of aquifer thicknesses. The analytical solutions accurately reproduce all numerically modeled scenarios with an average error of less than 3 %. The proposed method can be of practical use when considering or designing an HT-ATES system.     

The role of impact and radiogenic heating in the early thermal evolution of Mars

Journal of Earth System Science - The planetary differentiation models of Mars are proposed that take into account core–mantle and core–mantle–crust differentiation. The numerical...     

On the origin of the low energy cosmic rays from stellar sources

The model of stellar origin of the anomalous component in the low energy cosmic rays for He to Fe ions observed in space vehicles is studied in the light of recent results. The model of heliospheric origin by Fisket al which has several attractive features cannot explain the long-term variations of intensity observed during 1974 to 1978 as pointed out by Nagashima and Morishita. The stellar origin model of Durgaprasad and Biswas, on the other hand, can easily account for the sudden appearance of the anomalous component in 1972 and its large decrease in intensity in 1978 on the basis of polarity reversal of the solar magnetic field as discussed by Nagashima and Morishita (1980). In this work, we show that in the stellar model energetic ions of He, C, N, O, etc. could originate in O-type stars which manifest very strong stellar wind with mass loss rate of 3·10^?6 M_⊙ per year. These have terminal velocities of about 1200 to 4000 km/sec and are typically a few times their escape velocity. These velocities correspond to ion energies of 10 to 100 keV/amu. These ions are in partly ionised state and are accelerated in the interstellar shock fronts to about 1 to 50 MeV/amu and thus account for the observed anomalous component of low energy cosmic rays.