南海礼乐盆地礁体水热循环及其对地温场的影响

南海礼乐盆地自渐新世以来持续发育碳酸盐岩礁体,礁体区地温场可能受到礁体与周围低温海水间水热循环的扰动.为了解礁体与周围海水间的热交换过程及其对礁体区地温场的影响,以便从位于礁体区的钻井测温数据中提取深部热信息,本文以过礁体区S-1井的地震剖面为基础,在流热耦合条件下对礁体内的水热活动进行数值模拟.结果表明,礁体与海水间存在水热交换,该水热活动对礁体区温度场有明显的扰动,使得礁体上部温度和地温梯度明显降低,进入礁体下伏地层后,地温梯度逐渐趋于正常;水热循环对礁体区地温场的影响程度与礁体的厚度和渗透率密切相关,礁体厚度越大、渗透率越高,礁体及其下伏地层温度越低;计算剖面中,2100 m厚礁体之下可能存在约400 m厚、渗透率约为3×10^-12 m^2的高渗碎屑岩层,高渗层上覆礁体平均渗透率估计介于1×10^-13~5×10^-12 m^2之间.分析表明,在受水热活动影响的礁体区,礁体下伏地层中的热流可近似代表礁体区的深部热背景,S-1钻井深部热流介于65~75 mW·m^-2之间.

水-热循环花岗岩的物理力学性质试验研究

为了研究水-热循环次数对花岗岩物理、力学性质的影响,将花岗岩进行不同次数的高温-水冷循环处理,并将处理后的花岗岩在刚性试验机上进行单轴压缩力学试验。结果表明:在相同水-热循环次数下,随着温度的增加,花岗岩试样的饱和吸水率分阶段增加,峰值强度与弹性模量持续下降,变形模量下降,峰值应变呈现多阶段变化;在相同的温度作用下,随着水-热循环次数的增加,花岗岩试样的饱和吸水率逐渐增加,峰值强度和弹性模量出现先下降、后小幅上升、最后持续下降的变化现象,变形模量出现多阶段变化,峰值应变小幅度上升后下降;花岗岩单轴压缩破坏的应力-应变曲线分为4个阶段,随着温度的升高,花岗岩延性增加,应力-应变曲线幅度逐渐减小,压密阶段与累进性破裂阶段都增长,峰后曲线从光滑跌落过渡到分段跌落,随着循环次数的增加,呈现出相似变化趋势;温度的升高和循环次数的增加都导致了花岗岩内部缺陷和孔隙的增加,即随着饱和吸水率的增加,峰值强度减小,可见花岗岩的物理力学性质在不同温度、不同循环次数水-热循环后发生了不同程度的劣化。研究结果对分析花岗岩变形破坏机理以及实际工程中评价高温岩石工程的稳定性提供了一定的参考依据。

冻土–复合土工布界面复合幂–指数本构模型研究

土工合成材料广泛应用于各种工程中,由于土体与土工合成材料的物理力学特性差异明显,且土体易受水热条件影响,不同条件下界面的剪切力学特性存在明显的差异,界面的应力应变曲线也存在较大的形态差异。为准确描述冻土–复合土工布界面剪切特性,基于在不同水热循环工况下进行直剪试验得到的试验数据,提出了一种改进的复合幂–指数界面本构模型,并对得到的模型参数进行了分析和讨论。结果表明该模型能准确地反映不同类型的软化型和硬化型曲线,模型中不同参数有其对应的明确物理意义。针对不同复杂工况条件下的应力应变关系进行有效的拟合,并结合具体试验工况给出典型的有代表性的拟合函数关系式,对冻土区基础工程建设具有指导和参考意义。

华北平原大型灌区生态水文综合观测网络设计

清华大学水利水电工程系在华北平原地区建立生态水文综合观测网,进行农田生态水文综合试验研究。该观测网络通过对不同空间和时间尺度的水、热、物质循环的连续观测,形成对不同时间和空间尺度水循环机理的系统认识,为现代水文学与水资源科学的发展提供试验数据。同时,将该网络与卫星遥感观测相结合,可以将田间观测推广到全灌区,对指导该地区农业水资源管理和制定社会经济可持续发展规划具有重要的实践意义。该观测网络测量项目完整,观测手段先进,可为其他类似站网的建设提供参考。

水热循环作用对红砂岩动态力学特性的影响规律研究

红砂岩经过200℃的水热循环热损伤处理后,在SHPB试验装置上进行了2种加载速率下的动态冲击压缩力学试验,得到不同水热循环次数作用后的全应力-应变曲线,分析了水热循环次数对红砂岩的冲击压缩峰值应力的影响规律,探讨了水热循环对红砂岩的热损伤机制。研究发现,经历水热循环作用后,红砂岩表面出现了裂隙和脱落现象,内部结构也受到严重损伤,质量、密度和单轴抗压强度都随循环次数的增加而降低;经历水热循环作用后,全应力-应变中压密阶段较自然状态时相比,持续时间较长且较明显;在加载速率相同时,峰值应力随循环次数的增加而减小,峰值应变受循环次数的影响不明显;水热循环作用后红砂岩仍有应变率效应;最后对红砂岩在水热循环作用下的热损伤机制进行了探讨。研究成果可为水热环境下的岩体工程提供理论参考和技术支持。

冀中坳陷深部碳酸盐岩热储调查评价JZ04井

为紧密结合京津冀一体化经济社会发展需求,以缓解大气污染现状、实现节能减排为目标,面向宏观决策与工程应用需求,为京津冀地区冬季供暖提供清洁能源支撑,在冀中坳陷地区开展深部碳酸盐岩热储调查评价,探测深部碳酸盐岩热储层的结构特征,查明地热流体的水热循环条件,明确深部地热成因机制;开展深部碳酸盐岩热储改造与地热资源开发利用相关技术研究,实现深部碳酸盐岩热储资源量的分层评价,形成沉积盆地区深部碳酸盐热储勘查开发技术支撑体系,为冀中坳陷区深部碳酸盐岩热储地热资源开发利用提供示范,助力实现我国北方地区冬季清洁供暖规划目标。

不同竹龄、部位竹材经软化后的力学性能比较研究

以毛竹为研究对象,对3个竹龄(1.5、3.5和5.5年生)和5个纵向高度段竹材进行水煮软化处理,比较研究水煮软化后不同年份,不同部位竹材顺纹抗拉强度,顺纹抗压强度,静曲强度和抗弯弹性模量的变化情况,以了解其变化规律。结果表明:1在水煮软化循环实验处理下,毛竹的顺纹抗压强度、顺纹抗拉强度,抗弯弹性模量均呈现下降趋势;2从竹龄来看,在水煮软化循环作用下,5.5年生的毛竹材的各项性能变化差异最小,性能较稳定;1.5年生的毛竹材的性能变化差异最大,较不稳定。3从5个纵向高度看,毛竹材自下而上的顺纹抗压强度、顺纹抗拉强度的变化差异逐渐减小,即毛竹的基部的性能的变化最大,较不稳定,梢部的性能变化最小,较稳定。

Experimental study on characteristics of transcritical heat pump water heater using refrigerant HFC125

To evaluate the performance of heat pumps using refrigerant HFC125,an experimental rig of a DC-inverter heat pump water heater is designed and set up,and the research on the transcritical heat pump water heater is carried out experimentally.It is found that there is a top value of the coefficient of performance（COP）when the system runs at 95 Hz of frequency.The relationships between the COP and compressor frequency,condensation pressure,evaporation pressure,condensation water temperature rise,and discharge temperature are discussed and analyzed at 95 Hz.And the COP of the HFC125 transcritical cycle is also compared with that of a R410 subcritical heat pump under the same conditions.The results indicate that there exists an optimum frequency for a better COP,and the system COP shows an increasing tendency with the decrease in condensation pressure and compressor ratio while the evaporation pressure remains invariant,and the COP decreases rapidly when cooling water temperature rises over 47.5 ℃.Compared with the R410A sub-critical cycle,the COP of HFC125 transcritical cycle significantly increases by 12% on average.

湿热环境下ERM路面力学特性

环氧树脂碎石混合料（Epoxy Resin Mixture,简称ERM）是由环氧树脂胶粘剂与单级配或间断级配骨料按一定配合比拌合而成的新型路面材料,其孔隙率范围一般在15%~35%,具有良好的透水性,属新型透水路面,主要用于人行道以及景观道路。针对ERM在高温多雨地区路面工程中的应用环境,采用无侧限抗压强度试验研究3种粒径、两种岩性的环氧树脂碎石混合料材料在水-热循环作用下抗压强度损失规律以及特点,寻求环氧树脂与碎石的最佳粒径以及岩性组合。结果表明：经历5次水-热循环作用后,对4种不同粒径、不同岩性的环氧树脂碎石混合料进行无侧限抗压试验,ERMa、ERMb、ERMc、ERMd的强度损失依次为9.35%、10.41%、13.91%、20.66%。因此,在高温多雨环境下,使用ERM作为铺面材料时,对该种材料的水热循环破坏要给予重视。

基于ANSYS对HRHCM随形绝热结构热响应分析

采用ANSYS软件模拟分析模芯水热性快速热循环热响应过程,提出了一种带有随形绝热层和随形换热通道的组合式模芯换热结构,分析该特殊模具结构和绝热条件对加热冷却效率和模温均匀性的影响。结果表明,使用该结构,加热和冷却阶段所用时间分别缩短125.0%和136.8%;加热速率和冷却速率分别提高124.2%和135.8%;加热和冷却阶段最大温差分别降低9.0%和24.2%。

Subtropical Mode Water in the Northwestern Pacific

Based on the in situ XBT and other data sets, by analyzing the seasonal cycle of the mixed layer depth (MLD) and using the conservative potential vorticity (PV) as a tool, a clear description of the formation process of the North Pacific Subtropical Mode Water (NPSTMW) is presented for explaining the well known 'Stommel Demon'. The forming of NPSTMW reflects well the ventilation process of the isotherms of the permanent thermocline. The formation process can be divided into the 'ventilation' phase and the 'formation' phase. In the first phase (October-March), with large heat losses at the sea surface from October, the mixed layer deepens and correspondingly, the water mass with low PV emerges and sinks. After continual cooling from October to March, the mixed layer reaches its maximum value ( >300 m) in March. Then, in the second phase (April-June), the mixed layer shoals rapidly from April, a large part of the low PV water mass is sheltered from further air-sea interaction by the emerging seasonal thermocline, and thus forms new NPSTMW. Further analysis indicates that the formation region of warm NPSTMW (17-18℃) is limited between 140°-150°E, while the relatively cold NPSTMW (16-17℃) originates in a wider longitude range (140°-170°E).Climate features of NPSTMW are presented with the use of climatological Levitus (1994 a, b) dataset. It is shown that NPSTMW lies in the region of (130°-170°E, 22°-34°N) with core temperature ranging from about 16-19℃ and potential density around 25-25.8σθ NPSTMW has a three-dimensional structure lying below the seasonal thermocline (about 100 m deep) and reaches almost to 350m depths.

Crawlspace heating system in detached house with insulated foundation

Two practical crawlspace heating systems introduced in detached houses have been chosen as a field study. One is the crawlspace warm air heating system and the other is the crawlspace hot water circulation system. Based on the field study result, by using the simulation sol, ware, THERB, the effectiveness of the crawlspace warm air heating system has been examined. The effect of the factors, such as the wind amount circulating between crawlspace and indoor space, foundation insulation condition, and heat amount into the crawlspace, on the indoor thermal environment has been analyzed. Based on these analyses, the measured crawlspace heating system can make the average temperature of the living room above 20℃. These two houses have excellent thermal environment. According to the simulating result, heat amount input into crawlspace, which can make comfortable indoor thermal environment, for every month in heating period has been roughly concluded, and they are 600 W in December and March and 800 W in February and January, respectively.

Performance analysis of a zeotropic mixture(R290/CO_2) for trans-critical power cycle

Low critical temperature limits the application of CO_2 trans-critical power cycle.The binary mixture of R290/CO_2has higher critical temperature.Using mixture fluid may solve the problem that subcritical CO_2 is hardly condensed by conventional cooling water.In this article,theoretical analysis is executed to study the performance of the zeotropic mixture for trans-critical power cycle using low-grade liquid heat source with temperature of200℃.The results indicated that the problem that CO_2 can't be condensed in power cycle by conventional cooling water can be solved by mixing R290 to CO_2.Variation trend of outlet temperature of thermal oil in supercritical heater with heating pressure is determined by the composition of the mixture fluid.Gliding temperature causes the maximum outlet temperature of cooling water with the increase of mass fraction of R290.There are the maximum values for cycle thermal efficiency and net power output with the increase of supercritical heating pressure.

Numerical Study on Viscosity Reduction in Mining Heavy Oil by Circulating Hot Water

Viscosity reduction is an important process in mining heavy oil.To predict the temperature variation and viscosity variation of heavy oil in flow direction,computational fluid dynamics(CFD) was adopted to simulate the process of heat transfer and flow in this paper.Moreover,an objective function,namely viscosity reduction efficiency,was established to analyze the effect of viscosity reduction.The results indicate that circulating hot water can reduce viscosity significantly,and that the effect of viscosity reduction depends on the inlet temperature and inlet volumetric flow rate of hot water.There is a maximum temperature of heavy oil in flow direction.With the inlet volumetric flow rate of 2.0m3/h and the inlet temperatures of 60,℃,70,℃ and 80,℃,viscosity reduction efficiencies are 94.6%,96.7% and 97.3%,respectively.With the inlet temperature of 70,℃ and the volumetric flow rates of 1.5m3 /h,2.0 m3/h and 2.5m3/h,viscosity reduction efficiencies are 94.4%,96.7% and 97.2%,respectively.

Adsorption Refrigeration Performance of Shaped MIL-101-Water Working Pair

A new metal-organic framework of MIL-101 was synthesized by hydrothermal method and the powder prepared was pressed into a desired shape. The effects of molding on specific surface area and pore structure were investigated using a nitrogen adsorption method. The water adsorption isotherms were obtained by high vacuum gravimetric method, the desorption temperature of water on shaped MIL-101 was measured by thermo gravimetric analyzer, and the adsorption refrigeration performance of shaped MIL-101-water working pair was studied on the simulation device of adsorption refrigeration cycle system. The results indicate that an apparent hysteresis loop ap-pears in the nitrogen adsorption/desorption isotherms when the forming pressure is 10 MPa. The equilibrium ad-sorption capacity of water is up to 0.95 kg·kg^-1 at the forming pressure of 3 MPa （MIL-101-3）. The desorption peak temperature of water on MIL-101-3 is 82℃, which is 7 ℃ lower than that of silica gel, and the desorption temperature is no more than 100 ℃. At the evaporation temperature of 10 ℃, the refrigeration capacity of MIL-101-3-water is 1059 kJ·kg^-1, which is 2.24 times higher than that of silica gel-water working pair. Thus MIL-101-water working pair presents an excellent adsorption refrigeration performance.

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.

Energetic and Exergetic Analysis of Organic Rankine Cycle Powered by Hot Geothermal Water

The paper presents an investigation of energy and exergy analysis of an existing ORC （organic rankine cycle） unit powered by hot geothermal water. The validated model of this unit was used to examine 25 refrigerants belonging to different chemical compositions. The study revealed that R141b and R123 produced the best net power, energy efficiency, and exergy efficiency, whereas R125 was the lowest. Hydrofluorocarbons （except R143a）, hydrocarbons, and inorganic reflected attractive energy and exergy efficiencies. All investigated mixtures gained low performance compared with other studied candidates. The R245ca was the best among the hydrofluorocarbons studied refrigerants, and R501 was the best among the mixture refrigerants. Furthermore, within the ORC system, the evaporator was found to have the highest exergy destruction and the refrigerant pump was the lowest.

梯级水库三维环境流体动力学数值预测和水温分层与累积影响规律研究

该文应用美国三维水环境流体动力学模型(简称EFDC模型)对特大型水库进行了水流水温数值耦合预测计算,深入研究了水库的水热循环规律,并对分层型水库的水位、流速和水温分布规律进行剖析。在梯级水电站联合运行环境下,重点分析了高坝大库水温分层规律,探讨了建库前后的水温变化规律和梯级水库建设的累积影响,为调整梯级水电规划方案提供科学决策依据。