Flashing point compressibility of geothermal fluids with low CO2 content and its use in estimating reservoir volume

In this study, the bubble point pressure effect or, as it is more commonly known, the flashing point effect of CO₂ on geothermal fluids is shown, and the compressibility of the geothermal fluids containing low concentrations of dissolved CO₂ at the flashing point is formulated for isoenthalpic phase change. The compressibility, termed the isoenthalpic flashing point compressibility, can be calculated with well-known parameters. New, easy-to-use graphs are presented to estimate the compressibility for such systems. Correction for ionic strength of the geothermal brine is also considered. The practical use of the compressibility is illustrated to estimate the fluid content of a geothermal reservoir. A material balance method incorporating the isoenthalpic flashing point compressibility in geothermal modeling is investigated. The material balance method presented in the paper is of primary importance in the evaluation of geothermal reservoirs since both the areal extent and the vertical thickness can not be accurately determined, particularly in the initial development stages of the reservoirs. Applications of the method to geothermal fields are discussed.     

Investigation on the compressive properties of the three dimensional four-directional braided composites

The compressive mechanical properties of three dimensional (3D) braided composites are of key concern for design in actual engineering application. A representative volume cell (RVC) is chosen to study the uniaxial compressive mechanical properties of the braided composites with different braid angles by combing damage theory and finite element method. The fiber misalignment and longitudinal shear nonlinearity of braid yarn are considered in the computation model. And their influences on the compressive behavior of the braided composites are also evaluated. The damage development of constituents within the braided composites are obtained and analyzed. The main damage and failure modes and their interaction of braid yarn are provided as well. The numerical results are found that the compressive mechanical behavior of the braided composites with lower braid angle is sensitive to the fiber initial imperfection of braid yarn. The strength of the braided composites with different braid angle is controlled by the different microscopic failure modes.     

空调室外机内置安装角度对效果的影响

分析了在高层建筑空调室外机在内装情况下,其摆放角度对空调运行效果的影响。     

华北地区各类煤储层孔隙、吸附特征及试井成果分析

为系统总结华北地区各煤类的主要物性特征,指导煤层气的勘探开发,对该区各种煤类共205件煤样进行了压汞实验,分析了各煤类孔径结构的比孔容、比表面积特征。基于180件煤样的高压等温吸附实验,探讨了朗格缪尔体积（V_L,daf）、朗格缪尔压力与煤级的关系,发现朗格缪尔体积与煤级的关系呈现出两段式变化模式,即煤化程度在R_o,max＜4%之前,V_L,daf随R_o,max的增加而增大,当R_o,max＞4%后,V_L,daf随R_o,max的增加而减少,而朗格缪尔压力与煤级的关系复杂,数据十分离散。基于该区煤层气试井成果（170层次试井储层压力、204层次试井渗透率）,划分了煤储层试井储层压力、试井渗透率类型：该区以欠压储层为主,占69.4%左右,正常压力储层占27.1%,超压储层仅占3.5%,储层压力梯度总体随埋深的增加呈现出增大的趋势;超低渗透储层占26.0%,低渗透储层占36.8%,中渗透储层占18.1%,高渗透储层占19.1%,试井渗透率总体随埋深的增加而减少。     

欠平衡钻井溢流风险分析方法

川渝地区采用欠平衡钻井技术提速效果明显,但在钻进过程中,易发生发现气层后关井不及时,压井循环排气套压过高的问题。对欠平衡钻井溢流风险进行评估,可以为每口欠平衡井制订安全预案提供理论依据。为此,利用实钻资料,对欠平衡钻井潜在的溢流风险进行了分析,提出了欠平衡钻井前开展溢流风险分析的方法。其核心是：根据欠平衡井钻遇的地层特性,预测不同欠压值下的地层出气量,再通过压井计算确定循环排气时的最大套压值,最后判定允许的溢流量及关井时间。以四川盆地合川构造的合川X井为实例进行了计算,计算结果与实钻结果相符,证明上述欠平衡钻井溢流风险分析方法是切实可行的,并提出了控制欠平衡钻井溢流风险的对策与措施。通过分析欠平衡钻井溢流风险、规范欠平衡操作、明确施工细节,可以确保及时发现溢流、及时关井、严格控制溢流量,进而实现快速安全钻井。     

工程结构极限承载力上限分析的弹性模量缩减法

基于弹性模量缩减法和基准体法,建立了工程结构极限承载力上限分析的方法。该法结合弹性有限元法进行迭代分析,以广义屈服函数表达的单元承载比作为弹性模量调整的控制参数,根据单元承载比均匀度确定模量调整的阀值——基准承载比,利用单元应变能转化中的能量守恒原理建立单元弹性模量调整策略,通过缩减高应力单元的弹性模量模拟结构弹塑性损...     

PP/碳纳米管复合材料的制备及电性能

采用原子转移自由基(ATRP)活性聚合方法在多壁碳纳米管(MWNT)表面接枝丙烯酸丁酯聚合物(PBA),并以此对聚丙烯(PP)进行改性。红外光谱(FT-IR)及透射电子显微镜(TEM)测试结果表明,采用ATRP法成功地将PBA接枝到多壁碳纳米管(MWNT)表面。对PP/MWNT复合材料电性能研究表明,MWNT-PBA的添加比MWNT-COOH更能降低复合材料的电阻率。MWNT-PBA的加入可使PP从绝缘材料转变为抗静电材料。MWNT-PBA和MWNT-COOH加入PP都能提高材料的电性能,而MWNT-PBA比MWNT-COOH的作用更加明显。     

驾驶员对北京市道路交通标志的感知和理解

通过模拟在交通标志引导下到达指定地点的过程,研究了北京市道路交通标志信息量以及驾驶员脑力负荷对感知和理解道路交通标志的影响.在已有研究的基础上,改进了交通标志信息量的计算方法.相关分析结果表明,该方法很好地拟合了驾驶员对交通标志信息量的主观评价.方差分析结果表明:1)信息最的大小对驾驶员感知和理解交通标志没有显著影响;2)脑力负荷对交通标志识别率、决策时间、决策正确率以及决策确信程度有显著影响;3)脑力负荷对主观任务负荷和识别交通标志的时间没有显著影响.     

卧式行星磨粉磨水泥熟料的最佳参数研究

采用自行设计的卧式行星球磨机,在公转转速为300 r/min、自转与公转转速比为2.5的条件下,研究装球率、料球体积比、填充率对水泥熟料粉磨的影响。结果表明:成品粉体产率随装球率的增大呈增加趋势,在装球率为6.00%～10.51%时尤为明显,装球率大于10.51%时,增加趋势开始变缓;在固定填充率下,料球体积比为0.5时,成品粉体产率最大为65.80%;料球体积比为0.5,总填充率为35%时,成品粉体产率最大为68.56%。     

Numerical simulation of coupled radiation‐convection heat transfer of high‐temperature developing flow in tube

By combining the discrete ordinate method with the control volume method, the coupled radiation‐convection heat transfer of high‐temperature developing laminar flow in a tube is investigated numerically. The radiative transfer is solved by the discrete ordinate method and its contribution to thermal balance is dealt with as a source term in the energy equation, which is solved, as well as the momentum equation, by the control volume method. The effects of medium optical thickness and tube wall temperature on the temperature distribution in medium as well as the heat flux and local Nusselt number on wall are analyzed. The results show that the radiation heat transfer of high‐temperature medium influences the temperature distribution and convection heat transfer greatly, and plays an important role in the heat transfer of developing laminar flow in a tube. © 2003 Wiley Periodicals, Inc. Heat Trans Asian Res, 33(1): 53–63, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.10135