半导体激光抽运源大通道水冷热沉的接口设计

针对普通大功率半导体激光抽运源用大通道水冷热沉热阻高、工作时热沉表面在大通道水流方向存在明显温升进而导致加载其上的激光bar寿命不一致以及抽运源整体光谱宽度难以控制的问题,利用商用有限元软件ANSYS仿真获得抽运源工作时不同冷却水流量条件下热沉内部温度场分布,分析该结构热沉热阻系统的构成及整体热阻瓶颈所在。实际中通过改变冷却水接口结构,获得“入口效应”,提高了大通道热沉整体换热性能,进一步减小热沉表面温度梯度。利用所设计的新接口大通道水冷热沉获得3 bar线阵120 W连续(CW)输出半导体激光器抽运源,输出中心波长为807.7 nm,光谱宽度(FWHM)为2.8 nm。     

固态组件冷板热扩展体性能分析

固态技术和相控阵雷达是雷达领域研究的重要课题,固态末级功放组件、T／R组件内晶体管等大功耗、高热流密度器件在冷板上会形成局部热障,产生扩展热阻。文中对扩展热阻特性进行研究,探讨了影响扩展热阻的三个参数：厚度、对流换热系数和导热系数,并分析得出提高热扩展体的等效导热系数是减小扩展热阻、强化传热最有效的技术途径之一,最后在此基础上利用数值模拟方法对铜块、热管及蒸发室等三种热扩展体的散热性能进行了分析和比较。     

中央空调制冷机的化学清洗

阐述了中央空调制冷机结垢的类型及其产生的原因和危害，分析了中央空调制冷机的冷媒水系统、冷却水系统的化学清洗技术和操作方法。     

LED筒灯复合结构热管散热器的数值模拟

为解决LED筒灯使用单纯自然对流散热扩散热阻过大、温度分布不均的问题,提出一种基于平板热管和热虹吸管的复合结构热管散热器,并用数值模拟的方法研究了热功率、翅片高度、翅片数目、辐射换热对该散热器性能的影响。模拟结果表明应用于LED筒灯的复合结构热管散热器的热阻随着热功率的增加而减小,翅片高度和翅片数目存在一个最优值,使得散热器温度和热阻最小,自然对流情况下不可忽视辐射换热的作用。     

管道及设备中的垢层

论述冷却水系统垢层的成因及对设备的影响,只有控制结垢方可安全生产,节约能源。     

扰流小通道液冷冷板流动与传热特性的数值研究

为降低常规蛇形小通道液冷冷板的热阻,提高其对流换热能力,在流道内引入了一种强化换热结构,设计了扰流蛇形小通道液冷冷板,并利用数值模拟方法对两者进行了比较分析。相比于常规蛇形小通道液冷冷板,新的流道设计能够显著降低冷板的总热阻和进、出口压降,降幅分别可达9.2%和66.7%。此外,冷板平均努赛尔数(Nusselt, Nu)提高了17.2%。对冷板内部流动和传热情况进行了详尽的数值分析,研究了扰流小通道的强化传热效果及其作用机理。     

固态T/ R组件冷板扩展热阻分析与优化准则

电子设备的功率器件和散热冷板之间由于存在面积差异,产生扩展热阻,在高热流密度条件下(>100 W/ cm2 )温升效应尤为明显。文中通过对固态T/ R组件冷板扩展热阻的简化近似解的分析计算,研究了冷板的导热系数、厚度、半径、对流换热系数等参数扩展热阻的影响规律,发现冷板存在厚度和半径的工程最优值使得扩展热阻或总热阻最小,建立了相应的尺寸优化准则,然后通过计算流体力学(computiatonal fluid dynamics,CFD)数值试验进行了计算验证,结果表明CFD解和简化解结果一致,研究结论可用于指导冷板或热扩展板的工程设计。     

LED简灯热管散热器的试验研究及性能评价

为获得基于自然对流的异型热管散热器用于LED筒灯的工作性能,研制了热管散热器试验件,并进行了试验研究。结果表明：热管散热器启动性能良好,启动时间约为33min;散热器具有较好的均温性能,40W时蒸发面最大温差为4．7℃;在试验条件下,热源表面最高温度不超过70℃;加热功率对接触热阻、扩散热阻和热管热阻基本无影响,而翅片换热热阻随加热功率的增加而减小。基于试验所得结果,并通过热阻网络分析,论证了异型热管散热器可满足LED筒灯散热的需求。     

回路热管换热性能的实验研究

为研究回路热管(LHP)的换热性能,制作了简单的回路热管换热性能测试装置。采用不锈钢为回路热管的材料,500目铜丝网为吸液芯,实验研究了回路热管不同功率下对启动时间和热管热阻的影响。研究结果表明,回路热管的功率增大,启动时间越短,热阻也相应的减小;同时,回路热管冷凝器入口和储液室入口的温度在LHP启动后,会呈现相反的温度波动。研究结果为回路热管散热器的应用提供了理论依据和方便的测试手段。     

空调水处理技术在北京地铁6号线工程的应用与研究

通过对物理法、化学法、物理法和化学法相结合的三种空调水处理方法的比较,空调水系统腐蚀、结垢、微生物繁殖的原因分析,并以空调水处理技术在地铁6号线工程的应用实例,说明空调循环冷却水系统采用化学药剂法辅以旁滤水处理的方法,空调循环冷冻水系统采用全流量处理与全流量过滤的纯物理方法,从根本上解决了循环水的腐蚀、结垢、菌藻,悬浮物及水质保持、浓缩倍数控制及排污量控制等问题。     

Transient Characteristics of a Two-Phase Thermosyphon Loop for Multichip Module

A new thermosyphon cooling module (TSCM) has been designed, fabricated and tested to cool the multi-chip module plugged into a planar packaging system. The cooling module consists of a cold plate and an integrated condenser. With an allowable temperature rise of 56°C on the surface of the heater, the cooling module TSCM can handle a heat flux of about 2.7 W/cm² using R11 as working fluid. The transient characteristics of the cooling module have been proved to be excellent: that is, when a heat load is applied inside of the system, steady state can be achieved within 10 to 15 minutes. It has been found that the length of the vapor channel between the cold plate and the condenser in addition to the ambient and the condenser temperatures affect the system performance.     

Improved fabrication techniques for infrared bolometers

Techniques are described for producing improved infrared bolometers from doped germanium. Ion implantation and sputter metalization have been used to make ohmic electrical contacts to Ge:Ga chips. This method results in a high yield of small monolithic bolometers with very little lowfrequency noise. When one of these chips is used as the thermometric element of a composite bolometer, it must be bonded to a dielectric substrate. The thermal resistance of the conventional epoxy bond has been measured and found to be undesirably large. A procedure for soldering the chip to a metalized portion of the substrate is described which reduced this resistance. The contribution of the metal film absorber to the heat capacity of a composite bolometer has been measured. The heat capacity of a NiCr absorber at 1.3K can dominate the bolometer performance. A Bi absorber has significantly lower heat capacity. A low-temperature blackbody calibrator has been built to measure the optical responsivity of bolometers. A composite bolometer system with a throughput of ～0.1 sr cm² has been constructed using our new techniques. In negligible background, it has an optical NEP of \(3.6 \cdot 10^{ - 15} W/\sqrt {Hz}\) at 1.0K with a time constant of 20 ms. The noise in this bolometer is white above 2.5 Hz and is somewhat below the value predicted by thermodynamic equilibrium theory. It is in agreement with calculations based on a recent nonequilibrium theory.     

充液量对回路热管性能的影响

实验研究了以Cu粉烧结块为吸液芯、Al制太阳花散热器为冷凝器的回路热管(LHP)在不同充液率条件下充入工质为无水乙醇后的启动、温度波动以及热阻等传热性能。Cu粉烧结块吸液芯相对丝网吸收层可以产生更大的毛细力,Al制太阳花散热器可以使整个LHP更轻便,利于不同安装场合的应用。研究结果表明:1)LHP的启动受热负荷大小和充液率共同作用;2)温度波动随功率的增加而变得平缓,而随着充液率的增加,温度波动频率却有所上升;3)充液率影响LHP的热阻变化,最佳充液率为60%。     

Performance Analysis of a Thermoelectric Solar Collector Integrated with a Heat Pump

A novel heat pump system is proposed. A thermoelectric solar collector was coupled to a solar-assisted heat pump (TESC-HP) to work as an evaporator. The cooling effect of the system’s refrigerant allowed the cold side of the system’s thermoelectric modules to work at lower temperature, improving the conversion efficiency. The TESC-HP system mainly consisted of transparent glass, an air gap, an absorber plate that acted as a direct expansion-type collector/evaporator, an R-134a piston-type hermetic compressor, a water-cooled plate-type condenser, thermoelectric modules, and a water storage tank. Test results indicated that the TESC-HP has better coefficient of performance (COP) and conversion efficiency than the separate units. For the meteorological conditions in Mahasarakham, the COP of the TESC-HP system can reach 5.48 when the average temperature of 100 L of water is increased from 28°C to 40°C in 60 min with average ambient temperature of 32.5°C and average solar intensity of 815 W/m², whereas the conversion efficiency of the TE power generator was around 2.03%.     

风冷机组热回收方法及应用

对风冷机组的热回收系统原理进行了分析,提出了一种利用冷凝热回收器提供生活用热水的方法和装置,并对该系统使用的经济性进行了分析,指出利用热回收系统可有效地节约能源。     

Performance Study of a Double-Pass Thermoelectric Solar Air Collector with Flat-Plate Reflectors

In this paper the results of the influence of flat-plate reflectors made of aluminum foil on the performance of a double-pass thermoelectric (TE) solar air collector are presented. The proposed TE solar collector with reflectors was composed of transparent glass, an air gap, an absorber plate, TE modules, a rectangular fin heat sink, and two flat-plate reflectors. The flat-plate reflectors were placed on two sides of the TE solar collector (east and west directions). The TE solar collector was installed on a one-axis sun-tracking system to obtain high solar radiation. Direct and reflected incident solar radiation heats up the absorber plate so that a temperature difference is created across the TE modules to generate a direct current. Only a small part of the absorbed solar radiation is converted to electricity, while the rest increases the temperature of the absorber plate. Ambient air flows through the heat sink located in the lower channel to gain heat. The heated air then flows to the upper channel, where it receives additional heating from the absorber plate. Improvements to the thermal energy and electrical power outputs of the system can be achieved by the use of the double-pass collector system with reflectors and TE technology. It was found that the optimum position of the reflectors is 60°, which gave significantly higher thermal energy and electrical power outputs compared with the TE solar collector without reflectors.     

A Study on Thermal Performance of Heat Pipe for Optimum Placement of Satellite Equipment

A study on the operation of a heat pipe with two heat sources has been performed to optimize the heat distribution of satellite equipment. A numerical modeling is used to predict the temperature profile for the heat pipe assuming cylindrical two-dimensional laminar flow for the vapor, and the conduction heat transfer for the wall and wick. An experimental study using the copper-water heat pipe with the length of 0.45 m has been performed to evaluate the numerical model and to compare the temperature distribution at the outer wall for the non-uniform heat distribution. The results on temperature profiles for the heat input range from 29 W to 47 W on each heater are presented. Also the correlation between the heat input and the temperature increase is presented for the optimum distribution on two heaters. The result shows that the outer wall temperature can be controlled by redistribution of heat sources. It is also concluded that the heat source closer to the condenser can carry more heat while maintaining lower temperatures at the outer wall.     

Resistance of a plane grid condenser moving through a plasma

The resistance of a plane grid condenser, moving in a magnetized plasma, is calculated using the quasi-hydrodynamic approximation for the plasma dielectric tensor. It is shown that, as a consequence of the anomalous Doppler effect, the resistance may become negative. Some implications for antenna measurements in the ionosphere are discussed.     

人字形波纹片空调冷凝器设计

应用换热模型计算空气流过人字形波纹片管束的换热及R134a在光滑管内的冷凝换热特征。通过样机试验,验证设计方法的可行性。通过研究说明,换热模型可以较好地应用于人字形翅片管式冷凝器的设计。