土壤蓄热与土壤源热泵集成系统的数值模拟

结合土壤源热泵技术推广中存在的问题和地下蓄能技术的优点,提出了土壤蓄热与土壤源热泵集成系统及其地下管群换热器的布置方式。并在能量平衡的基础上建立了地下管群换热器蓄热、释热和停止运行的数学模型。通过数值模拟,分析了埋管间距对蓄热与释热的运行特性的影响。     

隧道塌方事故处理的研究与实践

通过对隧道坍塌的机理进行分析,及时采用了强支护,对隧道不同坍塌部位分别采取管棚法、小导管注浆法及二次衬砌加强及回填法等进行了处理,取得了理想的处理效果。     

大型相交管体类零件数控加工技术研究

分析了两相交管体类零件数控加工的难点,阐述了利用UG软件固定轮廓铣功能的进行相关零件加工的原理与特点,并结合实例说明了利用其进行管体相贯区域加工的一般步骤与方法。     

Design Guidelines for Polyethylene Pipe Interface Shear Resistance

Polyethylene pipes are commonly used in pipeline systems. Current methods used to determine the pipe pullout capacity do not consider the effects of diameter changes and cyclic movements that the pipelines may experience. Laboratory tests were performed to study the interface shearing resistance of polyethylene pipes under varying conditions. The tests were performed in a temperature-controlled room, where properties were investigated for thermal variations expected in the field. Two types of tests were performed: pull/push tests and cyclic tests. Test results indicated that reductions in pipe diameter affect the interface shear resistance that develops between the pipe and soil. As the pipe diameter gets smaller, the normal contact stresses at the interface decreases, causing a reduction in the interface shearing resistance directly proportional to the normal stress changes. Cyclic pipe movements also cause significant reduction in pipe pullout resistance. The test results indicated that the polyethylene pipe interface shear resistance can be significantly lower than the one determined using the current methods. This paper presents the test results, findings, and design recommendations for the pullout resistance of buried polyethylene pipes.     

Whistling behavior of periodic systems: Corrugated pipes and multiple side branch system

Whistling behavior of two geometrically periodic systems are investigated: corrugated pipes and a multiple side branch system. In both systems frequency (Helmholtz number) is a non-decreasing piecewise constant function of the Mach number, whose increase on average is approximately linear. The plateaus, lock-in frequencies, of this piecewise constant function correspond to the longitudinal acoustic pipe modes. In both systems pressure fluctuation amplitude changes non-monotonically with Mach number with local maxima that correspond to the lock-in frequencies. A characteristic length, equal to cavity width plus upstream edge radius, yields the smallest discrepancy in the measured peak whistling Strouhal number for both corrugated pipes and multiple side branch system. For both systems the upstream edge radius of the cavity has a strong effect on pressure fluctuation amplitudes. Whistling amplitudes increase by a factor of 3-5 upon rounding off the upstream cavity edges. The radius of the downstream edge has a less pronounced effect on the sound amplitude and frequency. The geometric parameters of the multiple side branch system can easily be modified. This makes the multiple side branch system a convenient tool for making experiments on the effects of various geometric parameters. A number of aspects are addressed with the multiple side branch system such as the effect of pipe termination geometry, source localization, side branch depth to diameter ratio, a gradient in depth along the pipe and hysteresis upon change in the acceleration or deceleration of the flow.     

Experimental investigation of the transient thermal performance of a bent heat pipe with grooved surface

A bent copper–water heat pipe with grooved inner surface has been investigated experimentally. A comparison between the bent and the straight heat pipes was performed at different inclination angle. Experimental results show that there is a small temperature difference between the condenser of the straight and that of the bent at the vertical orientation. The temperature difference increases as an inclination angle increases. Furthermore, the response time increases as the inclination angle increases. The thermal response of the straight to a sudden heat load is slightly faster than that of the bent. However, as the inclination angle increases to after the horizontal, the heat flux at the condensers decreases nonlinearly and the response time increases nonlinearly. A two-phase flow map has been proposed to explain the nonlinear performance of the thermal response and the heat flux, based on force balance among gravity, capillary, friction and buoyancy force acting on the working fluids. The nonlinear performance of the thermal response and the heat flux results from the capillary blocking due to formation of liquid bridge of two-phase flow. It was also found that the bent heat pipe is more sensitive to the change of the inclination angle than the straight in terms of the thermal response time and the heat flux of the condenser. The heat flux of the bent decreases faster than that of the straight after the horizontal orientation.     

A novel thermoelectric refrigeration system employing heat pipes and a phase change material: an experimental investigation

This paper presents results of tests carried out to investigate the potential application of heat pipes and phase change materials for thermoelectric refrigeration. The work involved the design and construction of a thermoelectric refrigeration prototype. The performance of the thermoelectric refrigeration system was investigated for two different configurations. The first configuration employed a conventional heat sink system (bonded fin heat sink) on the cold side of the thermoelectric cells. The other configuration used an encapsulated phase change material in place of the conventional heat sink unit. Both configurations used heat pipe embedded fins as the heat sink on the hot side. Replacement of the conventional heat sink system with an encapsulated phase change material was found to improve the performance of the thermoelectric refrigeration system. In addition, it provided a storage capability that would be particularly useful for handling peak loads and overcoming losses during door openings and power-off periods. Results showed that the heat sink units employing heat pipe embedded fins were well suited to this application. Results also showed the importance of using a heat pipe system between the cold junction of the thermoelectric cells and the cold heat sink in order to prevent reverse heat flow in the event of power failure.     

三次设计在热管换热器优化设计中的应用

利用可计算性项目的三次设计方法优选系统因素的最优参数组合。找出了热管换热器重要指标净回收热量的最优解,充分发挥了热管换热器在节能领域中的显著作用。同时,为完善热管换热器自身的优化设计提供了新的方法。     

转化炉管完整性分析专家系统(RTIES)的设计

针对RTIES的3个组成部分──炉管剩余寿命综合预测系统、炉管故障诊断系统和炉管性能数据库和知识库系统，介绍了其基本组成及设计思想，重点是寿命综合预测系统及故障诊断系统．对微机在转化管的运行和管理上的应用作了有益的尝试．     

贴边岔管有限元网格剖分与计算机实现

根据工程中对贴边岔管有限元前处理的要求,提出了一种可行的贴边岔管有限元网格曲面剖分与计算机自动生成方法.利用AutoCAD Object ARX开发工具,在Visual C++6.0编程环境下编程,实现了在AutoCAD绘图环境中自动生成三维网格曲面.且可与有限元软件ANSYS直接接口,使贴边岔管有限元处理及应力分析更为便捷,具有重要的应用价值.