Applied Mechanics and Materials Vols. 672-674

Abstract: Groundwater heat pump (GWHP) systems in three different hydrogeological fields, Beijing were selected, and their effects on temperature of groundwater in recharged aquifer were researched for three years. Results showed that the degree of thermal breakthrough was controlled by the distance between pumping wells and injection wells, and the temperature of groundwater with high flow rate can recover to normal faster than those with low flow rate. When distance between pumping wells and injection wells were shorter than 30m, thermal breakthrough may happen and the variation range of groundwater temperature during one heating or cooling period was 8~12°C.However, thermal breakthrough can be negligible and the temperature of groundwater may be steady when the distance between those wells was longer than 50m. Furthermore, GWHP in two different hydrogeological fields were selected to observe their effects on groundwater quality for one year. One GWHP was situated on the northwest piedmont alluvial fan of Beijing and the other was located in the southeast plain area of Beijing. Groundwater was sampled from those fields and thirty-two inorganic components were analyzed. Heavy metals were not detected, and calcium, magnesium, chloride, sulfate, fluoride and other ten inorganic components were studied. Groundwater quality in the northwest of Beijing was relatively steady because that aquifer was in relative oxidation environment. However, groundwater quality in the southeast of Beijing was subject to change because that aquifer was in relative reduction environment. Nitration reaction happened in the plain area, and ammonia, nitrite converted into nitrite nitrogen and nitrate nitrogen, respectively. Simultaneously, pH, concentrations of iron and manganese decreased, and total hardness increased.

Abstract: As the Key Components of a Horizontal Axis Tidal Current Energy(HATCE) Turbine, the Blades will be Affected by the Force of the Fluid when the Turbine is Working, which also Results in a Possible Effect on the Safety and Stability of the Tidal Current Energy Turbine. Thus, both the Structural Performance and Energy-Catching Efficiency of HATCE Turbine should be Paid Equal Attention. in this Study, Basing on the Workbench, the Energy-Catching Efficiency and Structure Performance of the Designed HATCE Turbine with Stainless Steel and Structural Steel at the Different Current Speeds are Comparatively Studied Using Unidirectional FSI Analysis Method. it can be Concluded that the Output Power of the Turbine is Lower at a Low Current Speed but its Energy-Catching Efficiency is Higher and Vise Versa. as a Result of Structure Performance Analysis, the Designed Turbine has Adequate Safetyunder all Loaded Conditions. Thus, the Designed Turbine Models are Available.

Abstract: In order to explore the characteristics of fire caused by sodium leakage in sodium-cooled fast reactor loop, an experiment on the sodium fire in form of columnar flow has been conducted. Temperature field characteristics were analyzed by measured results. Near the axis of the combustion container, the high-temperature region of the sodium fire in form of the columnar flow is located in the bottom and the temperatures are all less than 100°C at height from 0.5m to 2.0m under natural ventilation. The temperatures of the space reach the maximum values after forced ventilation and the highest temperature is up to 950°C at height 0.8m above the ground. Once the lateral distance to the sodium flow is more than 0.4m, the temperature field is affected less by the sodium fire in form of columnar flow.

Abstract: Titanium doped hollow glass microspheres (HGMs) with atom ratio of Ti to Si (Ti/Si) from 2% to 20% were fabricated by dried gel method. Effects of titanium concentration on elements distribution and properties of gels and HGMs were investigated. Results show that elements in both gels and HGMs distribute uniformly when Ti/Si is no more than 5%. On the contrary, sodium chloride are separated out and acetic acid volatilizes from gels with a higher titanium concentration and the elements distribution becomes nonuniform. Furthermore, loss of sodium and acetate ion results in insufficient blowing and refining during the process of fabricating HGMs, and further leads to the decrease of quality on morphology, geometry and uniformity of spheres.

Abstract: In recent years, piezoelectric energy harvester which can replace the traditional battery supply has become a hot topic in global research field of microelectronic devices. Characteristics of a trapezoidal-loop piezoelectric energy harvester (TLPEH) were analyzed through finite-element analysis. The output voltage density is 4.251V/cm2 when 0.1N force is applied to the free end of ten-arm energy harvester. Comparisons of the resonant frequencies and output voltages were made. The first order resonant frequency could reach 15Hz by increasing the number of arms. Meanwhile, the output voltage is improved greatly when excited at first-order resonant frequencies. The trapezoidal-loop structure of TLPEH could enhance frequency response, which means scavenging energy more efficiently in vibration environment. The TLPEH mentioned here might be useful for the future structure design of piezoelectric energy harvester with low resonance frequency.

Abstract: This paper presents an optimal design model for the floating platform catenary mooring system and applies it to a floating hybrid ocean renewable power generation system. The mathematic description on the model is established based on catenary theory and static analysis method and a MATLAB toolbox is developed to get the optimized mooring system design. A numerical verification to the mooring system’s performance in AQWA is then carried out and proves the effectiveness of the presented optimization model.

Abstract: More and more attention is paid to geothermal energy because of its cleanability and renewability. Geothermal power generation technology has quantities of advantages and the research is booming. There are three main types of geothermal power generation technologies namely dry stream, flashed stream and binary power generation. It is discussed that working principles, cycle efficiency, advantages and disadvantages, and application. Technology development trend is introduced. The technologies in the future are hot dry rock, magma, combined cycle and low temperature geothermal energy power generations. And they are all of great potential and application prospect.

Abstract: Nuclear energy as an economical, safe and clean energy is being increasingly concerned, and nuclear power stations have also been widely built in the world. However, because of the impact from nuclear events, the safety of nuclear power station has been suspected by the public. First, the development situation of the nuclear power station in the world is described. Then the nuclear power station containment is introduced. Meanwhile, the safety performance of nuclear power station containment under external events are analyzed. Some advices on guaranteeing the security work of nuclear power station containment are given.

Abstract: With advances in technology, Internet of things have been all over every aspect of our lives, renewable energy harvesting technologies will provide a better solution for the power supply of wireless sensors. This article outlines a variety of renewable energy, renewable energy equipment already, the advantages and disadvantages of renewable energy in the environment. Effective use of renewable energy will be the future hot research of energy development.

Abstract: There are various applications for geothermal energy. Geothermal heating is one form of great importance. The working principle is introduced. Then the origin and development are studied. Both the advantages and disadvantages are discussed, mainly compared with traditional radiator heating. Some related issues are studied too. All in all, there is a booming prospect in markets for geothermal heating.