Applied Mechanics and Materials Vols. 71-78

Abstract: Natural gas downhole choke process inlet is high temperature and high pressure. Usually it can achieves 10~30MPa, while it will be higher in high pressure drilling well. It is installing thousands of meters underground. It is difficult carrying on field test during working process. These special situations make the choke outlet flow being complex, which includes expansion wave, compression wave, and energy transformation. The physical experiment is difficult. To be more accurately analyzing the compressible viscous turbulent motion of downhole choke internal flow field, this article uses RNG − model for three dimensional numerical simulation. It analyzes the result of flow field streamlines, velocity, Mach number, pressure, and temperature distribution. It analyzes the influence on hydrate formation of choke working process. Numerical calculation can provide useful reference for the prevention of natural gas hydrate formation and optimization design of downhole choke.

Abstract: The current domestic conditions of sintering waste heat generation are introduced. The waste heat utilization methods are given according to waste heat characteristics of 360m2 sintering machine. The particle regenerative heat exchanger model is used to calculate heat transfer area of the first part of the circular-cooler. The logarithmic mean temperature difference method is used to calculate the heat transfer of closed cycle cooling air and the temperature of exhaust gas. The thermodynamic analysis of sintering heat generation process is completed. The power generation efficiency and quantity are calculated by using the heat balance and exergy analysis method.

Abstract: Experiment of a ground source heat pump system in cold area is studied in this paper. The results indicate that when the operation time increases to 100 hours, COPHP (COP of the heat pump) and COPSYS (COP of the system) decrease from 3.54 and 2.63 to 2.53 and 1.92, respectively. The average values of COPHP and COPSYS are 3.1 and 2.3, respectively. COPHP and COPSYS with 2 compressors at work are 11% and 12.2% higher than COPHP and COPSYS with 4 compressors at work, respectively. The average COPSYS with inverters is 6.42% higher than the COPSYS without inverters.

Abstract: The western countries has long established their strategic petroleum reserve system, most typically in the US and Japan. The paper analyzes and compares the strategic petroleum reserve systems in the US and Japan which are representative to the western world, and proposes the basic approach of establishing strategic petroleum reserve system in China.

Abstract: Based on the EES software, a heat transfer coefficient calculation program about double pipe heat exchanges is established. Some experimental data are compared to the simulation data for proving that the program can predict the heat transfer coefficient of the double pipe heat exchangers, and then the change of heat transfer coefficient is calculated and analyzed with relevant parameters. The results show that the heat transfer coefficient of heat exchanger are increasing with the flow of the shell side, the tube side and the logarithmic mean temperature difference, and when the temperature difference equals to 12°C, the total heat transfer coefficient can up to 2400W/m2.K or so.

Abstract: An experimental setup is designed and constructed to study the heat transfer coefficient of the double pipe heat exchangers in this paper. The influence of the mass flow of the shell side and the logarithmic mean temperature difference is studied. The experimental results demonstrate that the heat transfer coefficient of the exchanger increase with increasing of the logarithmic mean temperature difference and the mass flow of the shell side. Over a range of above mentioned parameters conditions, the average heat transfer coefficient of the exchanger can reach to 2300， 1500 W/m2.K respectively. The heat capacity and outer water temperature increase with the inlet water temperature increasing, and the pressure drop decreases with the inlet water temperature increasing.

Abstract: A novel separating flat heat pipe radiator was developed for high power rectification equipment，the physical and mathematic heat transfer model was built; The influences of the charging ratio, coil diameter and interbank combination on heat transfer limitation and temperature uniformity were researched; The characteristics of heat transfer system with four different kinds of interbank combinations between the new type of heat pipe and the common were analyzed . The results indicate that the heat transfer limitation and temperature uniformity of the new type of heat pipe can be improved when the charging ratio and the interbank combination were at the high-points. The charging ratio is in the range of 125%-175%，the interbank combination of the heat pipe heat sink is 4×10mm，the junction temperature of high power rectification equipment can be controlled steadily under 25°C for the heat load of 620W，and shall be very promising heat—transfer devices for controlling junction temperature of high power rectification equipment．

Abstract: It had been a key point and a tough work to verify the warning limit of urban housing market for those who research the housing market. The warning limit of domestic housing market was based on the change rate of its own indicator. It deviated from the changing trend, and diverged from the real feeling of our people. This research adopted systematized method and signal light system, and Taichung City was selected for a case study. The research result showed that it was practicable to apply the systematized method to researching warning limit of urban housing market. Therefore, it was suggested that the systematized method should be used as an auxiliary method on researching the warning limit of urban housing market so that the early warning function of urban housing market could be perfect.

Abstract: Boron and its compounds play an important role in modern energy and material sciences for the bight application prospect. The applications of boron and its compounds in material fields especially advanced materials including permanent magnetic, superconducting, boride cermets, boron-based fuel-rich propellants and borate whisker materials were summarized in this paper, and the new trend for the exploitation and application was also pointed out.

Abstract: Magnesium chloride hexahydrate (MgCl2•6H2O), which has a melting temperature of 389.7 K and latent heat of 168.6 kJ/kg, is one of the cheapest materials used as the thermal energy storage material. Like most hydrated salts, MgCl2•6H2O also has the problems of supercooling and phase segregation to limit its application. In this paper, some new progresses on magnesium chloride hexahydrate as phase change materials are summarized, and the new trend in the future is pointed out.