超宽带双模制导共孔径集能器研究

论述了超宽带反辐射导弹 (ARM)采用复合制导的必要性 ,指出了ARM宽带被动寻的与红外成像寻的双模制导的关键技术是共孔径集能器。分析论证了适合于共孔径集能器的超宽带微波被动寻的器的方案 ;根据红外成像的机理选择了红外成像前端焦平面阵。设计了共孔径集能器结构 ,对微波天线阵进行了测试 ,其测试结果说明了这种共孔径集能器实现的可能性。

太阳能集能器自动跟踪装置

太阳能集能器自动跟踪装置是由传感器、方位角跟踪机构、高度角跟踪机构和自动控制装置组成。自动跟踪装置驱动太阳能集能器 ,使集能器的主光轴始终与太阳光线相平行。当太阳光线发生倾斜时 ,传感器输出倾斜信号 ,指示执行器动作调整太阳能集能器的角度 ,直到太阳能集能器对准太阳 ,实现自动跟踪太阳的目的。在阴天或太阳光辐照度低于工作照度时自动关机 ,太阳光辐照度达到工作照度时自动开机。该装置适用于聚光式太阳能集能器。

环境振动特性和压电型集能器的研制

基于变电站变压器的工作环境特征,测试分析变压器的振动特性,获得其振动频率为100 Hz,加速度峰值为0.416 m/s2,据此设计和制备压电型集能器,确定其尺寸参数,并对其输出性能进行系统研究。器件在0.416 m/s2加速度激励下输出电压随振动频率的变化关系显示,在100 Hz时电压峰值达到9.4 V。设计的集能器谐振频率与变电站变压器振动频率一致,非常适于变电站变压器振动能量收集和应用,对于支持变电站故障抢修具有十分重要的意义。

压电式可穿戴集能器的研究现状及发展趋势

给出了压电能量收集的基本工作原理,分析了机电耦合工作模式的应用场合,并列出了部分压电式集能器的现有设计。从人体生物力学角度介绍了足底受力情况以及鞋样对足底受力的影响。详细介绍了压电式足部动能集能器的常用材料及现有收集方法,并分别阐述了不同收集方法的研究现状。最后,指出了今后主要需解决的问题,总结了压电式可穿戴集能器的发展趋势。

双模制导共孔径集能器技术研究

分析论证了超宽频带微波被动寻的与红外成像寻的双模复合制导的关键技术即共孔径集能器技术 .提出了方案 ,进行了结构设计并加工了样件 .经测试得到了满意的效果 。

人体能量收集的研究现状

比较了现有人体能量集能器收集方式的功率密度,分析了各种人体能量集能器供电的可行性。讨论了环境能量集能器的功率密度及优缺点,并列出了人体能量集能器相对环境能量集能器的优势。介绍了人体能量的分类以及人体驱动所能产生的能量。针对人体的能量分布和利用潜力,详细介绍了人体的动能、热能、化学能和呼吸能等人体能量的现有收集方法,并分别阐述了每种能量的不同收集方法的研究现状,进一步探讨了电磁式、压电式、摩擦电式、静电式、复合式、热电式及燃料电池等收集方式的优缺点,指出人体能量收集器的研究前景。

面向能源互联网的新型能源子网系统研究

提出面向未来能源互联网的以新型全可控柔性配电装备:电能交换器和电力集能器为核心的能源局域网与能源子网层次化配用电侧灵活配电系统架构,在此基础上,结合信息物理系统对以电力集能器为核心的能源子网进行了较详细的研究,并详细设计了电力集能器的系统结构,给出了其核心模块的主电路拓扑,同时提出了适用于当前应用场景下的能源子网组网模型,并对各种运行工况和暂态过程下的能源子网进行计算机仿真分析,论证其可行性和有效性。

电力电子化进程下的交直流无缝混合灵活配电系统研究

该文从当前配电网所面临的众多挑战出发,结合当前与未来配电系统中电力电子化进程的发展现状和趋势,提出了以新型全可控柔性化配电装备为核心的网格状层次化架构的交直流无缝混合灵活配电系统及其组网模型,并在原有研究基础上详细设计了新型配电装备的系统结构,并对其核心模块多种主电路拓扑和控制策略进行了研究。最后搭建了多机级联运行的交直流无缝混合灵活配电系统计算机仿真模型,经对各种暂、稳状态的仿真分析,论证其可行性、有效性和优越性。

折射微透镜阵列的非成象光学特性研究

本文针对微透镜阵列与红外焦平面阵列集成的应用，对折射性微透镜阵列的非成象光学特性进行了研究和总结．采用系统性能评价因子来衡量微透镜的聚能效率，分析了系统参数对会聚效率的影响，并用标量衍射方法对几何光学分析结果进行了校验。

智能微电网能量管理系统设计与应用

设计一种基于电力集能器的微电网能力管理系统,由能源局域网、能源子网能量管理系统组成,采用专家控制策略多种策略,正常运行、故障处理和孤岛运行模式。电力集能器自带电网交流、微网直流、负荷交流转换等功能满足系统负荷的不同供电需求,通过微网及光伏起到能量协调平衡功能。主要能源从交流电网获取,光伏与直流微电网做为辅助能源,该系统主要负责系统级控制与协调,在子网系统实现电能管理及电能平衡。通过对微网能量管理、储能技术的高效利用、储能数据的集中管理分析,在削峰填谷、节省电费开支、延缓输配电扩容升级等方面具有良好的经济效益。

Experiment and numerical simulation on flow and heat transfer in all-glass evacuated tube solar collectors

The experimental study of natural convection in allglass evacuated tube solar collectors is performed through the experimental platform of the solar-assisted fuel cell system.The experimental facility includes solar collectors with different length and diameter tubes, different coating materials, and with / without guide plates, respectively. Threedimensional mathematical models on natural and forced convections in the solar collectors are established and the experimental data is validated by field synergy and entransy principles. The results of natural convection show that the water temperature increases and thermal efficiency decreases gradually with the evacuated tube length. The thermal efficiency increases when absorption rates increase from 0. 95 to 1. 0 and emission rates decrease from 0. 16 to 0. 06. The thermal efficiency of solar collectors is increased after being equipped with the guide plate, which is attributed to the disappearance of the mixed flowand the enhancement of the heat transfer at the bottom of the evacuated tube. The results of forced convertion indicate that the Reynolds, Nusselt and entransy increments of the horizontal double collectors are higher than those of the vertical single collector while the entransy dissipation is lower than that of the vertical single collector. It is concluded that the solar collectors with guide plates are suitable for natural convection while the double horizontal collectors are suitable for forced convection in the thermal field of solar-assisted fuel cell systems with lowand medium temperatures.

船舶应充分利用太阳能来节约能源

一、前言科学技术的迅速发展,为人类利用太阳能展现了广阔的前景。既有应用于高科技方面的宇宙航天器太阳能电池板、蓄电池,也有用于日常工作、生活方面的太阳能航标灯、太阳能灶等。但对于船舶来说。

Improving performance of flat plate solar collector using nanofluid water/zinc oxide

In this article,the effect of using water/zinc oxide nanofluid as a working fluid on the performance of solar collector is investigated experimentally.The volumetric concentration of nanoparticles is 0.4%,and the particle size is 40 nm,and the mass flow rate of the fluid varies from 1 to 3 kg/min.For this experiment,a device has been prepared with appropriate measuring instruments whose energy source is solar radiation.The solar energy absorbed by the flat plate collector is absorbed by the nanofluid of water/zinc oxide.The nanofluid is pumped to the consumer,a heat exchanger,where it heats the water.The temperature,radiation level,flow rate,and pressure in different parts of the device were measured.The pressure drop and the heat transferred are the most important results of this experimental work.The ASHRAE standard is used to calculate efficiency.The results showed that the use of water/zinc oxide nanofluid increases the collector performance compared to water.For 1 kg/min of mass flow rate,the nanofluids have a 16% increase in efficiency compared to water.From the results,it can be concluded that the choice of optimum mass flow rate in both water and nanofluid cases increases efficiency.

Performance investigation of solar thermal collector with auxiliary heater for space heating

In this paper,the performance of a solar thermal system with a focus on space heating was investigated.A 70 m^(2) detached house was considered in the weather conditions of the city of Tehran,Iran.A thermosyphon solar water heater with a flat plate collector combined with an auxiliary electrical heater supplies the heating demand of the house.The proposed system was modeled and analyzed using TRNSYS software.In this regard,the TRNBuild module was employed for the building load calculation.The model has been simulated for one year of operation.The effects of the solar collector’s surface area and storage volume were assessed.The results show that for a solar collector with a 15 m^(2) surface area,the solar fraction is 0.29 in January,during which the solar radiation is the lowest.Using solar collectors of10 m^(2) and 5 m^(2) surface areas,the solar fraction falls to 0.23 and 0.14,respectively in January.Besides,two cases of 150 L and 300 L storage tanks are taken into account.Eventually,it is found that using a 15 m^(2) solar collector and a 150 L storage tank can appropriately provide the building’ s heating demand taking the thermal performance and economic aspects into consideration.

Numerical analysis of flow and heat transfer behavior in fin-tube flat-plate solar collector

Temperature distribution over the absorber plate of a parallel flow flat-plate solar collector is numerically analyzed. The governing differential equations with boundary conditions are solved numerically using fluent software. Effects of the inlet mass flux, inlet temperature and tube spacing on velocity and temperature distributions are discussed. Numerical results show that the distributions of velocity and temperature of fluid is unsymmetrical inside pipe.

Influence of Heterojunction Position on SiGe HBTs with Graded BC Junctions

The influence of a heterojunction in the vicinity of a graded BC junction on the performance of npn SiGe HBTs is studied. SiGe HBTs differing only in heterojunction position in the vicinity of a graded BC junction are simulated by means of 2D Medici software for DC current gain and frequency characteristics. In addition, the simulated DC current gains and cut-off frequencies are compared at different collector-emitter bias voltages. Through the simulation results, both DC and HF device performance are found to be strongly impacted by degree of confinement of the neutral base in the SiGe layer, even in the absence of a conduction band barrier. This conclusion is of significance for designing and analyzing SiGe HBTs.

Integrated utilization of low-grade thermal energy in hot coal mine

This paper explores the integrated utilization of low-grade thermal energy in hot coal mines, based on analysis of original heating, refrigerating, mine draining, bath draining and air exhaust systems, and in combination with the actual conditions of Tangkou Coal Mine in Shandong Province. It presents a set of comprehensive and integrated utilization schemes for the various different kinds of low quality heat energy. With heat pumps, the recycling of the low quality heat energy from the drainage, bathing water and the exhaust air can occur in winter, and in summer, there exists condensed heat of the refrigerating system. When in conjunction with solar collectors, the thermal utilization of solar power can be realized for the whole year. The system achieves mine drainage and bathing water purification and recycling, as well as purifying exhaust air by water spraying. It also satisfies the demands of a whole year＇s bathing heat for the coal mine, with refrigeration in summer, and heating for the ground house and shaft house in winter. It is able to integrate different kinds of low quality heat energy and low emission drainage and dust, and can replace the traditional boiler heating system. Finally, the system reduces conventional energy consumption and the amount of mine water drainage.

Solar Desalination with Latent Heat Storage Materials and Solar Collector

Availability of clean water is going to become one of biggest demands of the country. Even though there arc various technologies available for purification of water harnessing solar energy fits the purpose for future problems. Distillation is one of many processes available for water purification, and solar energy is one of several forms of heat energy that can be used to energize this process. In this review a study is made to enhance the productivity of the solar stills by connecting solar still with latent heat storage and solar air heater in series and other factors like improving evaporation rate by maintaining Low depth, more exposure area, heat addition by solar collector and presence of latent heat storage material, which is a paraffin wax as a integral part of still. Latent heat storage is one of the most efficient ways of storing thermal energy. Unlike the sensible heat storage method, the latent heat storage method provides much higher storage density, with a smaller temperature difference between storing and releasing heat. Further augmentation of the yield by scraps, pebble, and sand are added.

Performance enhancement of filled-type solar collector with U-tube

In order to increase the efficiency of solar collector, a methodology is proposed based on the analysis of its influencing factors, such as thermal conductivity of filled layer, structure forms of filled layer and heat loss coefficient. The results of analysis show that the heat transfer between pipes in evacuated tube is one of the most important factors, which can lead to the decrease of the outlet temperature of working fluid. In order to eliminate the negative influence of the heat transfer between pipes, the hollow filled-type evacuated tube with U-tube(HUFET) was developed, and the heat transfer characteristics of HUFET were analyzed by theoretical and experimental studies. The results show that the thermal resistances decrease with the increase of the thermal conductivity of filled layer. When the thermal conductivity is over 10 W/(m·K), the change of thermal resistances is very little.Furthermore, the larger the thermal conductivity of filled layer, the less the rate of the energy transfer between the two pipes to the total energy transfer, which is between the absorber tube and the working fluid. There is a little difference between the efficiencies of HUFET and UFET, with the efficiency of HUFET 2.4% higher than that of UFET. Meanwhile, the validation of the model developed was confirmed by the experiment.

Effect of Distance between Double Glazing on the Performance of a Solar Thermal Collector Control

In this research paper, an attempt has been made to come across the effect of distance between double glazing on the efficiency of a solar thermal collector. Experiments were carded out on an active solar energy demonstration system （ET 200）. Commercial glass pane of 3 mm thick having the same dimensions as that of the apparatus was placed above the collector at a distance of 2 cm, 4 cm and 6 cm. Tests were done with and without the added glass. Experiments were performed for double glazing with two positions of the light meter. In one position, it was placed in the middle of the collector surface. While, in the other one, the light meter was placed in the middle of the added glass. To study the effect of double glazing on the performance of the solar collector ET 200, the correct position of the light meter was to place it exactly in the middle of the additional pane under the lamp. Double glazing does not enhance the performance of the solar collector because of the high resistance of the system glass air glass. The efficiency of double glazing solar collector decreases with the increasing the distance of the two separated glasses.