深层页岩气水平井井筒瞬态温度场研究与应用

深层页岩气水平井钻井过程井筒瞬态循环温度对旋转导向工具的选择具有重要作用。基于井筒与地层间的对流换热机理及能量守恒原理,建立了井筒瞬态温度场模型;分析了循环时间、排量、水平段长度和入口温度对井筒瞬态温度的影响;优选了页岩气水平井轨迹控制方法,提出了降低井底循环温度的工程措施。结果表明,上部井段环空钻井液循环温度随循环时间和排量的增加而增加,而下部井段环空钻井液循环温度反而降低;随着水平段长度增加,环空钻井液循环温度增加,水平段越长,循环降温效果越低;随着钻井液入口温度增加,钻井液出口温度增加,下部井段环空钻井液循环温度随入口温度的变化较小。当垂深超过4 000 m后,水平段较短时,可采用旋转导向钻井工具;水平段较长,井底循环温度高于135℃后,推荐采用螺杆配LWD测量工具。采用增加循环时间、排量及边循环边下钻的方式可降低井底循环温度,以确保旋转导向工具和LWD工具处于安全工作温度内。     

干湿-温度双循环作用下氯离子在混凝土中的传输性能研究

采用自然扩散法研究了混凝土在海洋环境中的氯离子扩散行为,探讨了水灰比、温度、干湿循环和温度循环对混凝土氯离子扩散性能的影响。试验模拟了干湿循环和昼夜温差循环作用对不同水灰比混凝土中氯离子传输的影响。结果表明,浪溅区混凝土要比水下区混凝土中氯离子扩散得更快,且温度循环对氯离子扩散有一定的影响,在实际工程中不能忽视昼夜温度循环对氯离子扩散系数的影响。     

季节温度循环后CFRP板-混凝土界面承载力模型研究

通过双面剪切试验,研究了-20～60℃的温度循环作用后CFRP板-混凝土界面极限承载力的变化规律。对比分析了未经季节温度循环和经历50、100、150次季节温度循环后材料的宏观力学性能、界面破坏特征和界面极限承载力等变化规律。结果表明：随着季节温度循环次数的增加,环氧树脂胶由于后固化作用,其抗拉强度、抗剪强度及弹性模量升高,伸长率有所降低;季节温度循环次数的增加对混凝土和CFRP板的力学性能影响较小;C30、C50混凝土强度界面破坏形式不同;随着季节温度循环次数的增加,界面极限承载力增加。同时,在Naubauer&Rostasy模型、Chen&Teng模型和陆新征模型的基础上,提出了季节温度循环后界面极限承载力修正模型,结果发现模型计算值与试验值吻合较好。     

蓄能地板供暖用相变材料热特性研究

介绍了用于蓄能地板供暖的相变材料及其封装技术,对水合盐类相变材料(TH29)进行了循环熔冻及热稳定性实验.实验采用恒温水浴箱的热水加热,强制、自然冷却相变材料的方式.相变材料TH29的相变温度为26～29 ℃,在若干次循环熔冻后可以保持热特性的稳定,相变温度变化不明显,可满足人体热舒适的需求.     

带一个回热器的Kalina循环的热力参数分析及优化

为了研究单一回热器对Kalina循环系统性能的影响,建立了带1个回热器的Kalina循环稳态数学模型,研究了循环的4个关键热力参数对Kalina循环净功和热效率的影响。对Kalina循环在不同热源温度下进行了热力参数优化,获得了循环在不同热源温度下的最大循环热效率。研究结果表明:在同一热源温度下,存在不同的最优蒸发器蒸发压力,使得循环净输出功和循环热效率分别达到最大值;循环净输出功和热效率随着蒸发器出口氨水溶液温度和氨水基本溶液浓度的增大而增大,随着透平背压的增大而减小;随着热源温度的增大,循环热效率逐渐增大,所对应的最优蒸发器蒸发压力和蒸发器出口氨水溶液温度逐渐增大,同时,透平背压和氨水基本溶液浓度逐渐降低。     

基于微热管阵列的地板辐射供暖模拟研究

提出了 1种基于微热管阵列的地板辐射供暖系统,建立了供暖单元传热模型,利用实验数据验证了模型的可靠性.并对该辐射供暖传热过程及关键影响因素进行了模拟与分析,得到了供水温度和循环流速对供暖性能的影响.当流速为0.2 m/s,不同供水温度下,地板表面温度的实验数据与模拟数据最大差值为1.6℃.地板表面温度均随着供水温度的增大增幅明显;在相同供水温度下,地板表面温度受循环流速影响较小.在供水温度为40℃,流速为0.2 m/s时,模拟地面温度在23.9～29.9℃之间,热媒输送通道细小通道扁管上方地板表面温度较高.提出地暖结构的优化方法,以减少地板温度不均匀性.     

空调冷源温度与冷水机组的能效

在阐明影响冷水机组能效的基础上,利用压焓图,对制冷循环进行了热力学分析,进而以表格的形式列出了制冷剂分别为R134a和R407c,冷凝温度为40℃,蒸发温度在5℃～16℃之间变化时,制冷理论循环的单位质量制冷量、耗功量及制冷系数的变化规律.结果表明,制冷剂分别为R134a、R407c时,蒸发温度每升高1℃,制冷系数平均...     

喷气增焓机械过冷CO2跨临界循环性能分析

提出了一种喷气增焓机械过冷CO₂跨临界循环,以研究循环喷气增焓与机械过冷耦合特性。建立喷气增焓机械过冷CO₂跨临界循环热力学模型,并采用EES(Engineering Equation Solver)软件对循环性能进行仿真分析。研究了主循环压缩机排气压力、中间压力、辅助循环过冷度以及环境温度对循环COP、排气温度、制热量、压缩机功等参数的影响,并在相同参数条件下与常规机械过冷循环进行对比分析。结果表明：主循环排气压力为9.7 MPa时取得最大COP为3.435,喷气增焓对机械过冷CO₂跨临界循环进一步降低排气温度有较明显效果;存在使循环COP最大的最优中间压力,相同中间压力下,喷气比取0.3、0.4、0.5时COP逐渐降低;提高过冷度使循环COP和排气温度降低,制热量和辅助循环压缩机功升高;环境温度变化时,中间补气焓值变化,进而使压缩机出口温度变化。     

循环荷载作用下煤变形及渗透特性的试验研究

利用自主研发的含瓦斯煤岩热流固耦合三轴伺服渗流装置,以型煤试件为研究对象,进行不同温度条件下循环荷载试验,研究循环荷载作用下煤变形及渗透特性。研究结果表明:(1)随温度的升高,煤循环形成的滞回曲线所围成的面积逐渐减小。在单个循环曲线中,加、卸载阶段的主应力差、渗透率与轴向应变曲线呈现"X"状;在同一循环周期下,轴向应变与渗透率随温度的升高逐渐减小;在同一温度下,轴向变形随循环次数的增加逐渐增大。(2)随温度的升高,加载阶段曲线斜率逐渐增加,累计变形总量降低,即提高了不可逆过程的发展速率。(3)在各温度条件下,加载阶段应变及渗透率在整个循环过程中的变化均不明显。卸载阶段应变及渗透率在第1次循环期间变化较大,但从第2次循环开始,应变随循环次数的增加趋于平缓。在相同循环次数下,体积应变随温度的升高逐渐增大,渗透率逐渐减小。     

连续焊接不锈钢金属屋面系统温度循环作用下工作性能试验研究与理论分析

以青岛胶东国际机场T1航站楼的连续焊接不锈钢金属屋面系统为研究对象,对其子结构模型试件进行了9次高、低温循环试验,并对屋面板、固定支座进行了应力实测,对屋面板的表面位移增量进行了实测.同时基于ABAQUS/Standard模块对该模型试件进行顺序耦合热应力分析,重点研究了屋面板和固定支座在极端加载温度作用下的变形与受力性能.结果 表明:屋面板和固定支座未产生明显变形现象,固定支座与下部构造之间及各层钢板之间均未出现自攻螺钉的松脱现象;随着温度循环次数的递增,不同循环下相同加载温度点的实测值数据波动较小,表现为较为稳定的趋势,模型试件耐候性能良好.通过数值模拟结果与试验结果的对比,验证了模型结构模拟分析的正确性和适应性.     

基于分层室温控制的太阳能热水低温地板辐射供暖系统模拟研究

本文构建了基于分层室温控制的太阳能热水低温地板辐射供暖系统,并以大连地区为对象,采用TRNSYS软件对其进行了模拟计算,预测太阳能供暖系统的运行情况,对室内温度、蓄热水箱温度以及集热器和辅助热源的运行情况进行了较详细的分析。在此基础上,针对软件模拟过程中组件的选择和太阳能供暖系统的设计提出了建议。     

封闭体系中煤体升温解吸的热力学特性研究

气体在煤中吸附解吸取决于其压力和温度,气体解吸量随温度升高和压力降低而有所增加。在封闭体系中,温度升高造成煤体解吸量增加,并引起体系压力变大,但同时抑制解吸。吸附态气体和游离态气体相互转化时,伴有能量交换。为研究煤体升温吸附/解吸的热力学特性,依据实际气体状态方程、玻尔兹曼能量分布理论以及两能态模型,得到了吸附热的数学表达式,并在物理实验基础上加以验证。实验结果表明:封闭体系内温度升高,升温促进解吸和加压促进吸附同时作用直至动态平衡,其中温度对解吸的促进作用要强于压力对解吸的抑制作用,体系整体表现为解吸作用;两能态模型能较准确地反映吸附热与温度和压力的变化关系,且吸附热是温度和压力的函数,其值与初始平衡条件有关,初始压力越大,吸附热越小,解吸时间越短,更易达到平衡。     

Integrating water temperature in chlorine decay modelling: a case study

Temperature is one of the factors that most influences chlorine decay rates in drinking water systems. The current paper assesses and demonstrates the importance of using a temperature dependent chlorine bulk decay model for the accurate prediction of disinfectant residuals in water supply systems. Chlorine concentration in a water transmission system was modelled for two seasons using a temperature-dependent bulk decay model at a constant and variable temperature. Results show that water temperature can vary within the system and that the accurate prediction of residuals may additionally require the incorporation of a water temperature model in the simulators. In this case study such approach was developed innovatively by establishing a water-age-dependent temperature function.     

汽车焊接车间通风空调数值模拟研究

本文针对一汽车焊接车间,采用PHOENICS软件,对模型A、模型B和模型C共3种通风方式下车间的速度场、温度场及污染物浓度场进行了数值模拟研究.模型A为不设空调系统的诱导通风方式,该方式由于无空调系统,车间内温度过高;模型B在模型A的基础上设置了空调系统,车间内的各参数基本达到了设计要求;模型C为局部通风方式,设有空调系统,该方式车间内的各参数也达到了设计要求,如果焊接地点稳定不变时,可采用此种通风方式.     

溶液除湿空调在档案库房中的应用

本文首先对档案库房所需要的环境进行了分析,指出档案库房除了要满足基本的温度和湿度要求外,还必须有一定的洁净度、空气酸度和霉菌量的要求。而后剖析了常规冷凝除湿空气处理机组在档案库房空调应用中的弊端,研究提出了适应于档案库房的基于温、湿度独立控制技术的溶液除湿空气处理技术。最后通过对常规空调与溶液除湿空调的能耗分析,得出溶液除湿空调与常规空调相比可显著节能的结论。     

采用水源热泵的低温地热水两级利用供暖能耗分析

本文介绍了采用水源热泵的低温地热水两级利用采暖方案在改造工程中的应用。根据供热系统的实际运行特点,提出了单位热成本的概念,在此基础上,使用BIN法对水源热泵采暖方案的全年运行能耗进行了计算并与燃气锅炉方案做了对比。分析结果表明,采用水源热泵的低温地热水两级利用采暖系统运行经济节能,具有明显的优越性。     

太阳能热水系统蓄热水箱温度分层作用研究

本文采用蓄热水箱的多节点模型，对典型太阳能热水系统进行了全年逐时模拟计算。计算数据表明，相比于完全混合的蓄热水箱，水箱温度分层可较大幅度提高太阳能集热器平均效率和太阳能保证率。同时还分析了不同气象条件、集热器类型和用水模式等条件下，蓄热水箱温度分层对太阳能热水系统性能提高程度的影响。     

Performance analysis of a ground-assisted direct evaporative cooling air conditioner

In this paper, the results of performance analysis of a ground-assisted hybrid evaporative cooling system in Tehran have been discussed. A Ground Coupled Circuit (GCC) provides the necessary pre-cooling effects, enabling a Direct Evaporative Cooler (DEC) that cools the air even below its wet-bulb temperature. The GCC includes four vertical ground heat exchangers (GHE) which were arrayed in series configuration. In order to have an accurate prediction of the optimum performance of a GCC, a computational fluid dynamic simulation was performed. Simulation results revealed that the combination of GCC and DEC system could provide comfort condition whereas DEC alone did not. Based on the simulation results the cooling effectiveness of a hybrid system is more than 100%. Thus, this novel hybrid system could decrease the air temperature below the ambient wet-bulb temperature. This environmentally clean and energy efficient system can be considered as an alternative to the mechanical vapor compression systems.     

Study on indoor thermal environment of office space controlled by cooling panel system using field measurement and the numerical simulation

The purpose of this study was to analyze the performance of a cooling panel system installed in the vertical plane with condensation (hereinafter a cooling panel system) using field measurement and coupled simulation of convection and radiation (CFD). Unlike an all-air cooling system, the cooling panel system could remove the cooling load by convection and radiation. Since the surface temperature of the cooling panel analyzed in this study can be controlled under the dew point, this system is expected to be energy-saving and dehumidifying. In the first step of this study, the indoor thermal environment of the office space, which is air-conditioned by a cooling panel system, was analyzed by field measurement and CFD. By comparing both results, the expected precision of CFD for an indoor space with a cooling panel was examined and the CFD method verified from a practical point of view. In the next step, the thermal environment of the model office space, which is cooled by three types of HVAC system (cooling panel system, all-air cooling system, and hybrid air cooling system composed of cooling panel and natural ventilation), was analyzed using CFD. Installing a human model in the office, the characteristics of heat transportation from the human model were also analyzed. The analysis deals with only sensible heat in this study. The operative temperature in the cooling panel system was lower than that in the all-air cooling system when each of the sensible cooling loads of all types of HVAC system was the same. In conclusion, the cooling panel system was found to be very energy-efficient.     

Freeze-proof method and test verification of a cold region tunnel employing electric heat tracing

In recent decades, numerous tunnels have been built in the cold region of China. However, frost damage occurs frequently inside the tunnels; this damage threatens the stability of the tunnels. In order to prevent frost damage, a method employing electric heat tracing (EHT) was presented in this study. Moreover, the EHT-based freeze-proof system layout and installation procedures were also introduced. The tunnel liner EHT system is composed of four parts: heating cable, insulation layer, protective layer and fire protection layer. This EHT system was adopted in the Dongnanli highway tunnel (located in northeastern China) to verify its applicability. In-situ test results indicated that the temperature behind the liner begins to heat up after one hour of electrifying the system; next, the temperature becomes positive and remains stable after three hours of electrifying the system. The operation of the heating system is quite stable, and the insulation effect is significant. Through the assessments of the heating efficiency that is required to reach the target temperature and a constant temperature heating effect, it is suggested that the combination of thermal insulation and electric heat tracing is feasible and effective in preventing frost damage in tunnels. The research results provide references for the design and construction of frost prevention systems in tunnels in cold regions.