南海热流特征及其构造意义

根据南海 592个热流数据 ,为克服热流站位分布不均及局部异常热流的影响 ,结合各单元的地质史及其地壳厚度等资料对研究区热流特征进行了详细分析。结果表明 ,具拉张背景的区域如北部陆缘、湄公盆地以及北巴拉望盆地具有中等偏高热流 ;海沟区热流相对较低 ,东部海沟区除台西南盆地外均为低热流区 ,而南部边缘东段古海沟区处于热恢复中 ;南部边缘西区因边界断裂的扭张及深部热源的异常补给而具高热流 ;属于剪切断裂带的西部陆缘也具高热流特征 ;中沙—西沙地区热流中等偏高 ,并由NW往SE方向增加 ,而南沙地区热流较低 ,约为 60mW·m- 2 ;海盆的热流基本满足随洋壳年龄增加而降低的规律 ,东部次海盆实测热流与理论预测基本一致 ,而西南次海盆实测热流普遍低于预测值 ;在南海北部下陆坡区识别出一条高热流带 ,该带与前人给出的海盆北缘断裂带位置基本一致。研究区不同区域地热特征直接或间接地受控于其所处的构造环境。据此 ,给出了研究区的热流趋势图。

中国东南地区各造山带大地热流特征

本文依据近几年在我国东南地区取得的125个大地热流数据,以区内造山带或造山带内主要大地构造单元为单位,分析和比较了各单元的大地热流特征。报道了反映各单元区域热背景的代表性热流值变化范围和平均值,为研究区内各造山带构造-热演化历史提供了重要参数。

红河流域元古界大红山群变质岩系的热储结构及热流特征

经过地热地质调查、物探验证和分析论证,在红河流域中段的戛洒盆地古元古界大红山群变质岩系中钻探获得了可供开发利用的热矿水。勘探孔深2 200.71 m,大红山群第4至第5段(Pt1dhs4-5)热储层富水性强,钻孔涌水量1 089 m^(3)·d^(-1),孔底测温84.3℃,地热水矿化度9 777 mg·L^(-1),水化学类型为Cl-Na型,水化学成分复杂。此次成功的勘探研究,揭示了大红山变质岩系的热储特征及地热资源潜力,拓展了地热水勘探开发的新领域。综合研究认为,大红山群变质岩系中的硬脆性大理岩、石英片岩、火成岩等热储层(带)、导热导水的深大断裂及上覆隔水隔热的三叠系红层等盖层,构成了较为典型的带状热储。热储层赋存承压地热水,主要由地下水在重力和热力作用下,沿区域深大断裂带的主干和次级导热导水断裂作深循环逐渐增温和对流运动所形成,实测地热增温率为3.0℃·(100 m)^(-1)。

天然气水合物的热流特征及影响因素

热流特征是研究天然气水合物的重要指标之一，不同地质环境下的天然气水合物的热流特征不尽相同。天然气水合物的热流分布主要受地壳年龄和沉积作用、地形及断裂构造和流体迁移等因素影响。

基于格子玻尔兹曼方法的双液滴撞击壁面液膜的热特性演化过程

为了研究并排双液滴撞击覆有液膜的高温壁面过程中壁面热流密度分布特征,基于水热耦合双分布函数格子玻尔兹曼伪势模型,探究了液滴间距、撞击速度和液相黏滞系数在不同时刻对壁面瞬时热流密度分布的影响。结果表明:低温液滴的扩散与下潜导致撞击区和中心射流区的壁面与液膜之间的温度梯度上升,引起撞击区和中心射流区壁面热流密度骤增。撞击区传热形式以对流传热为主,静态区受液冠处速度不连续性影响,其传热形式以扩散传热为主。双液滴撞击速度增大导致液滴下潜和扩展程度加深,液膜内部对流传热增强。双液滴间距增加引起双液滴内侧液冠在液膜内扩展空间增大,造成瞬时壁面高热流密度区域面积增加,利于散热。此外,更大的液相黏滞系数增大了液滴撞击液膜过程中的黏滞耗散,降低低温液滴的下潜程度和撞击区的液膜流场对流强度,导致壁面热流密度峰值减小。

雄安容东片区雾迷山组基岩热储开发条件的研究

地热资源作为清洁能源近年来在世界各国的发展中发挥着重要作用,地热作为一种可再生的洁净能源,与常规能源相比,对环境污染小,利于环境保护,且具有投资少、见效快的特点,它可减少传统燃料的消耗,且因其开采条件简单、用途广泛而日益受到人们的青睐。符合可持续发展、建设资源节约型、环境友好型社会的要求,对发展循环经济、实现节能减排目标、促进经济可持续发展具有重要意义。本文从地质背景、地热数据分析、热流特征地址与地热条件、水文地质条件等方面介绍了热储的开发条件。

Numerical Study on Heat Transfer and Flow Characteristics for Laminar Flow in a Circular Tube with Swirl Generators

This study investigated the heat transfer and flow characteristics of one kind of swirlgenerator in a circular heat exchanger tube through a numericalsimulation. The swirlflow induced by this type of swirlgenerator can obtain a high heat transfer rate with minimalpressure drop penalty. The simulations were carried out to understand the physicalbehavior of this kind of mesoscale heat enhancement component. By visualizing the heat transfer and flow characteristics, it is found that the swirlflow is induced by swirlgenerator in the circular tube couples with the impinging jet effect. After passing through the swirlgenerator, the localfriction factor of liquid can quickly return to lower levelmore quickly, while the localNusselt number maintains higher values for a distance; thus, the evaluation criterion of localperformance is improved. Single-factor optimization is used for three geometric parameters, i.e., the angle of swirlgenerator(25o, 45o, and 60o), the length of swirlgenerator(0.005, 0.01, and 0.02 m), and the center rod radius(1, 2, and 3 mm). The optimum parameters of the swirlgenerator for laminar flow of air in a circular tube are obtained, which should be 60o, 0.005 m, and 3 mm, respectively.

Investigations on pool boiling critical heat flux, transient characteristics and bonding strength of heater wire with aqua based reduced graphene oxide nanofluids

In the present work, the pool boiling critical heat flux, transient heat transfer characteristics, and bonding strength of thin Ni-Cr wire with aqua based reduced graphene oxide(r GO) nanofluids are experimentally studied. Results indicate:(i) the critical heat flux(CHF) of 0.01, 0.05, 0.1, 0.2, and 0.3 g·L^(-1) concentrations of r GO-water nanofluids varies from 1.42 to 2.40 MW·m^(-2);(ii) the CHF remains same for the tested samples during transient heat transfer studies and(iii) a constant value of CHF upto 10 tests when the nanocoated Ni-Cr wire is tested with DI water and deterioration occurs beyond this which implies a chance of peel off of r GO layer below the critical coating thickness.

Effect of heat flux and inlet temperature on the fouling characteristics of nanoparticles

In order to study the effect of heat flux and inlet temperature on the fouling characteristics of nanoparticles, and to further reveal the fouling mechanism for insights into proper operating conditions, γ-Al_2O_3/water suspensions were chosen as the subject of this research. The particulate fouling characteristics of γ-Al_2O_3/water suspensions on the surface of stainless steel have been experimentally studied by varying the heat flux and the inlet temperature under single-phase flow and subcooled-flow boiling conditions. The results show that in the condition of single-phase flow, the asymptotic value of fouling resistance decreases with increasing of heat flux and inlet temperature. The asymptotic value of fouling resistance under single-phase flow is much higher than for the subcooled-flow boiling condition. The effect of heat flux on the fouling resistance under the two flow states has an inverse relationship, and there exists a minimum value of fouling resistance between these two states. For subcooled-flow boiling, the asymptotic value of fouling resistance increases with increasing heat flux, whereas the effect on fouling resistance by the inlet temperature is negligible.

Characteristics of oil shale pyrolysis in a two-stage fluidized bed

Rapid pyrolysis of oil shale coupled with in-situ upgrading of pyrolysis volatiles over oil shale char was studied in a laboratory two-stage fluidized bed(TSFB) to clarify the shale oil yield and quality and their variations with operating conditions. Rapid pyrolysis of oil shale in fluidized bed(FB) obtained shale oil yield higher than the Fischer Assay oil yield at temperatures of 500-600 ℃. The highest yield was 12.7 wt% at 500 ℃ and was about1.3 times of the Fischer Assay oil yield. The heavy fraction(boiling point > 350 ℃) in shale oil at all temperatures from rapid pyrolysis was above 50%. Adding an upper FB of secondary cracking over oil shale char caused the loss of shale oil but improved its quality. Heavy fraction yield decreased significantly and almost disappeared at temperatures above 550 ℃, while the corresponding light fraction(boiling point < 350 ℃) yield dramatically increased. In terms of achieving high light fraction yield, the optimal pyrolysis and also secondary cracking temperatures in TSFB were 600 ℃, at which the shale oil yield decreased by 17.74% but its light fraction yield of 7.07 wt% increased by 86.11% in comparison with FB pyrolysis. The light fraction yield was higher than that of Fischer Assay at all cases in TSFB. Thus, a rapid pyrolysis of oil shale combined with volatile upgrading was important for producing high-quality shale oil with high yield as well.

Variation characteristics of aquifer parameters induced by groundwater source heat pump operation under variable flow

The variation characteristics of aquifer parameters,induced by groundwater source heat pump(GWSHP) operation under variable flow,were theoretically analyzed through a case study,in which the characteristics of building air conditioning load were considered.The results,compared with the constant flow operation,indicate that the influence on the variations of porosity,hydraulic conductivity and confined water head is decreased by 48%,51% and 71%,respectively,under variable flow operation.The security of variable flow operation is superior to that of constant flow.It is also concluded that the climate region and function of the buildings are primary factors which affect the suitability of variable flow operation in GWSHP.

Numerical investigation on flow and heat transfer characteristics of corrugated tubes with non-uniform corrugation in turbulent flow

Based on finite volume method, the pressure drop and heat transfer characteristics of one smooth tube and ten different axisymmetric corrugated tubes, including two with uniform corrugation and eight with non-uniform corrugation, have been studied. A physical model of the corrugated tube was built, then the numerical simulation of the model was carried out and the numerical simulation results were compared with the empirical formula.The results show that: the friction factor decreases with the increase of Reynolds number ranging from 6000 to 57000, the value of which in the corrugated tubes with non-uniform corrugation(tube 03–10) are smaller than those with uniform corrugation(tube 01–02). The geometry parameters of tube(01) have advantages on the heat transfer enhancement in low Reynolds number flow region(from 6000 to 13000) and tube(07–08)have advantages on the heat transfer enhancement in high Reynolds number flow region(from 13000 to 57000). The vortex, existed in each area between two adjacent corrugations called second flow region, is the root of the enhancement on heat transfer in the corrugated tubes. The effectiveness factor decreases with the increasing of Reynolds number and the performances of the corrugated tubes with pitch of 12.5 mm have advantages than these of 10 mm under the same corrugation geometric parameter.

NUMERICAL SIMULATION OF SSTA IMPACTS OVER THE GLOBAL OCEAN ON THE ANOMALOUS CIRCULATION OVER EURASIA IN JANUARY 2008

In this paper, we discussed the features of atmospheric circulations over Eurasia as a response to sea surface temperature anomalies （SSTAs） over the tropical Indian Ocean, the equatorial Pacific, Kuroshio and the North Atlantic. Our results are shown as follows： （1） CAM3.0, driven by the combined SSTAs over the four oceanic regions, can simulate well the features of anomalous atmospheric circulations over Eurasia in January 2008, indicating that the effects of the SSTAs over these four regions were one of the key causes of the anomalous systems over Eurasia. （2） The SSTAs over each key region contributed to the intensification of blocking over the Urals Mountains and a main East Asian trough. However, the influence of the SSTAs over individual oceanic regions differed from one another in other aspects. The SSTAs over the North Atlantic had an impact on the 500-hPa anomalous height （Z500A） over the middle-high latitudes and had a somewhat smaller effect over the low latitudes. For the warm SSTAs over Kuroshio, the subtropical high was much stronger, spread farther north than usual, and had an anomalous easterly that dominated the northwest Pacific Ocean. The warm SSTAs over the tropical Indian Ocean could have caused a negative Z500A from West Asia to Middle Asia, a remarkably anomalous southwesterly from the Indian Ocean to the south of China and an anomalous anticyclone circulation over the South China Sea-Philippine Sea region. Because of the La Nifia event, the winter monsoon was stronger than normal, with an anomalously cooler northerly over the southeastern coastal areas of China. （3） The combined effects of the SSTAs over the four key regions were likely more important to the atmospheric circulation anomalies of January 2008 over Eurasia than the effects of individual or partly combined SSTAS. This unique SSTA distribution possibly led to the circulation anomalies over Eurasia in January 2008, especially the atmospheric circulation anomalies over the subtropics, which were more similar to those of the winter E1 Nifio events than to the circulation anomalies following La Nifia.

Characteristics of Fluid Flow and Heat Transfer in the Shell Side of the Trapezoidal-like Tilted Baffles Heat Exchanger

Periodic whole cross-section computation models are established for segmental baffle heat exchanger, shutter baffle heat exchanger, and trapezoid-like tilted baffle heat exchanger. The reliability of models is verified by comparing the simulated results to the results obtained from the Bell-Delaware method. Due to the orthogonal assembly of the baffles, the shell side fluid shows the twisty flow of trapezoid-like tilted baffle heat exchanger. The essential mechanism on disturbing flow and heat transfer enhancement is revealed by defining the non-dimensional factor η of the shell side fluid flow direction of heat exchanger and the field synergy principle. The results show that at the same Reynolds number, the shell side fluid convection heat transfer coefficient of trapezoid-like tilted baffle heat exchanger is 12.43%-24.33% and 6.71%-11.51% higher than those of segmental baffle heat exchanger and shutter baffle heat exchanger, respectively. The shell side fluid flow velocity field and the pressure gradient field of trapezoid-like tilted baffle heat exchanger and shutter baffle heat exchanger decreases compared with that of segmental baffle heat exchanger, so the shell side fluid flow resistance and pressure drop is increased; the shell side comprehensive performance of trapezoid-like tilted baffle heat exchanger is 5.85%-9.06% higher than that of segmental baffle heat exchanger, and 15.27%-23.28% higher than that of shutter baffle heat exchanger. In this study, a baffle structure with higher efficiency of the energy utilization for the heat exchanger is provided.

On Identical Problems of Natural Convection in Enclosures and Applications of the Identity Character

In this paper, a concept of 'identical problems' of natural convection in enclosures is presented. A pair of problems of natural convection in enclosures is said to be identical if they look different in appearance but with appropriate selection of coordinates and appropriate definition of dimensionless variables for each problem, they will have identical geometric configurations and identical dimensionless governing equations and related boundary conditions. The identical characteristics of a pair of problems of natural convection in enclosures with an internal isolated island are demonstrated via dimensionless mathematical formulation and flow visualization results. Numerical computations are performed and the predicted streamlines agree with the flow visualization results. A number of other possible pairs of identical problems are also presented. Applications of the identical character are provided and assumptions under which the identical problems may exist are discussed.

Hydrodynamic and Heat Transfer Characteristics of Magnetofluidized Beds

To investigate the flow and heat-transfer behaviors of magnetofluidized beds, an experimental facilitywas designed. A constant uniform magnetic field is produced by a Helmholtz electromagnet. The nature of fiuidization and heat-transfer characteristics of a horizontal electrically heated tube immersed in the bed were measured. The bed material is iron shots. Depending upon the intensity of magnetic field (weak, moderate and strong), the bed pressure drop and heat transfer coefficient are classified into three ranges of magnetic fields. The range of variation of maximum magnetic-field intensity is from 0 to about 20690 A/m.

Numerical Prediction of Fluid Flow and Heat Transfer in a Wavy Pipe

Hydrodynamic and thermal characteristics in a pipe with sinusoidal wavy surface for steady laminar flow are invdtigted numerically in the present study. The integral forms of governing equations are discretized using control volume based Finite Volume method with collocated variable arrangement, SIMPLE algorithm is used and TDMA solver is applied for solution of system of equations. A pipe of length equal to 4λ is considered. Effect of surface waviness, determined by wavelength-amplitude ratio λ/a (=L), on flow and thermal field is presented. The simulation work has been carried out for L’=11.0 -30.0 for a Reynolds number range50 to 2000. Results are presented in the form of Streamfunction, isothermal lines, velocity and vorticity profiles, change of mean friction factor, variation in skin fiction. local and average Nusselt number with Reynolds number, wave number (n) and L’. For a particular geometry. length of circulation zone increases with Reynolds number and approaches a limiting value for higher Reynolds number. Wall shear stress in the bulge part of the chancel shows smaller values that affect largely the be of heat transfer and Nusselt number shows minimum values in this region. This circulation zone drastically increases with the increase of surface waviness showing high mean friction factor per wavelength. Mean friction factor inversely varies with Reynolds number. A correlation is proposed for calculating friction factor in the form f=C/(Re)m, where ’C and ’m’ represents two polynomials of degree 4 and 2 respectively and are function of L. Higher waviness of the surface shows the higher heat transfer rate than lower waviness. Heat transfer rate falls almost exponentially along the axial direction with the increase of wave number.

Condensation heat transfer characteristics of vapor flow in vertical small-diameter tube with variable wall temperature

To explore the condensation characteristics of vapor flow inside vertical small-diameter tubes, the classical Nusselt theory is revised and an analytical model with variable tube wall temperature is established by considering the effect of surface tension exerted by condensate film bending as well as the effect of shear stress on vapor-liquid interface. The effects of various factors including tube wall temperature and gravityon flow condensation in small-diameter tubes are analyzed theoretically to show the heat transfer characteristics. Comparison with the experimental data indicates that the proposed analytical model is fit to reveal the fundamental characteristics of flow condensation heat transfer in vertical small-diameter tube.