Improving the design of a photoconverter with a heat sink using mathematical simulation

The paper describes a mathematical model of an existing experimental apparatus: a photoconverter with a heat sink (PhCwHS). A comparison of experimental results in laboratory and natural conditions with the simulation results was performed.     

新型极小展弦比叶栅的叶型研究

以数值手段分析研究了具有不同极小展弦比的改型设计的后加载透平叶栅的内部定常三维粘性流动及损失，同时对该透平叶栅在不同出口马赫数和进气角下进行平面叶栅吹风实验。数值分析结果和实验结果表明，后加载叶栅在极小展弦比下能有效控制叶栅内二次流动的形成，具有低的三维叶栅损失。     

The parametric optimum design of a new combined system of semiconductor thermoelectric devices

By introducing an internal structure parameter, the characteristic curve of a new combined system consisting of a semiconductor thermoelectric cooler and a semiconductor thermoelectric generator is obtained. The maximum coefficient of performance and rate of refrigeration of the system and the corresponding values of other important parameters are calculated. Moreover, the optimal operating region of the system and the optimal range of the internal structure parameter of thermoelectric devices are determined. The results obtained here may provide theoretical guidance for the optimal design and operation of such a new combined system.     

新型多功能节能炉

在分析现有多功能炉优缺点的基础上,提出了新型多功能节能炉的设计方案;介绍了这种新型多功能炉的工作原理和使用方法,并对其进行了性能分析.这种多功能炉极具市场潜力与较好的市场前景.     

一种新型多功能节能炉的设计

分析了市场上几种多功能炉的优缺点 ,在继承其优点的基础上 ,对其缺点进行了改进 ,提出了一种新型多功能节能炉的设计方案。这种多功能炉极具市场潜力与较好的市场前景。     

Optical, electrical and photovoltaic characteristics of organic semiconductor based on oxazine/n-Si heterojunction

In this work, the construction and photoelectrical characterization of p-type organic semiconductor oxazine (OXZ) in junction with n-type silicon semiconductor are presented. The Stokes shift between absorption and emission of oxazine was analyzed. The analysis of the spectral behavior of the absorption coefficient (α) of OXZ, in the absorption region revealed a direct transition, and the energy gap was estimated as 1.82 eV. From the current–voltage, I–V, measurements of the Au/OXZ/n-Si/Al heterojunction in the temperature range 300–375 K, characteristic junction parameters and dominant conduction mechanisms were obtained. This heterojunction showed a photovoltaic behavior with a maximum open circuit voltage, V_oc, of 0.42 V, short-circuit current density, J_sc, of 3.25 mA/cm², fill factor, FF, of 0.35 and power conversion efficiency, η, of 3.2% under 15 mW/cm² white light illumination.     

空气制冷循环特性及一种新型涡流制冷装置研究

通过与蒸汽压缩制冷循环的比较,论述了空气制冷循环的特性,特别是空气制冷循环对解决环保问题的优良特性以及适用温度范围宽广的特点。并且提出一种新型涡流管制冷装置系统。     

一种基于太阳能热浮力的新型观瞄平台载体热数值分析

提出了一种基于太阳能热浮力的新型战场信息观瞄平台,根据辐射传热理论建立了太阳能热气球的热力学模型,使用FLUENT对太阳能气球的热特性进行了数值计算,获得了气球的蒙皮、内部空气的温度场,着重分析了在太阳辐射下达到平衡状态时热气球直径对蒙皮表面及其内部空气温度分布的影响。结果表明,当气球在太阳辐射下达到平衡状态时,气球蒙皮最高温度为348 K,内部空气的平衡温度为334 K,蒙皮最大温差为25K左右,气球蒙皮温度分布沿竖直方向梯度较大。     

A new lattice thermal conductivity model of a thin-film semiconductor

In the present study, a new lattice thermal conductivity model for a thin-film semiconductor is proposed. This model is considered, compared to the existing models, to be more mathematically consistent in the sense that the heat flow is contributed solely by the low-dimensional phonons, and the spatial confinement effects not only on the phonon group and phase velocities but also on the Debye temperature are taken into consideration. To count the boundary scattering effect, an analytical or empirical boundary scattering rate is suggested and added to the total scattering rate via the Mattiessen’s rule. It is found this newly proposed model predicts as well as the existing models and reasonably well with the experimental data.     

新型椭圆截面螺旋扭曲组合管换热特性的数值模拟

提出了一种新型换热管型,即椭圆截面螺旋扭曲组合管。以场协同理论为指导,通过改变管型形状参数组合方式,对椭圆截面螺旋扭曲组合管进行数值模拟及分析,并进行不同Re数下圆管换热Nu数与经验公式对比,结果表明:组合比为0.4,长短径比为2.0,扭曲角度为90°时,综合性能最优,确定椭圆截面螺旋扭曲组合管对换热的强化是有效的,模拟结果是可信的。     

An experimental investigation of a different type vapor compression cascade refrigeration system

Experimental investigation and theoretical study of a different type of two-stage vapor compression cascade refrigeration system using R-134 as the refrigerant are presented. Performance evaluations of two single stage vapor compression systems and two-stage vapor compression refrigeration cascade system are performed with respect to theoretical model developed. In the first section of the experiments, one refrigeration system, namely RU2, is operated. During the experiments, rate of the water flow connecting both systems is kept constant at various values and the voltage across evaporator heaters is increased from 100 to 200 V with intervals of 20 V. In the second part of the first category, experiments are repeated by using different mass flow rates of water. In the second section, two separate refrigeration systems, namely RU1 and RU2 are connected to each other by using the water loop. This system is also called cascade refrigeration system. It is observed that the change in water mass flow rate has little effect on the coefficient of performance for single stage and cascade stage refrigeration systems. It is also observed that the coefficient of performance is mainly a function of evaporator temperature and pressure. When RU2 operating in the single stage refrigeration system is compared with RU2 operating in the two-stage cascade refrigeration system at the same refrigeration load interval (360–460 W), the average percentage values of the decrease in the condensing pressure, the decrease in the compressor power and the increase in the COP are 21.9, 31.7 and 32.7, respectively.     

High-efficiency solar cells based on semiconductor nanostructures

Thin film solar cells are promising for large-scale commercial applications due to their low manufacturing costs. However, a major problem with thin film technology is material nonuniformity associated with the fabrication of large area films. We are developing a technology for fabricating high-efficiency solar cells based on semiconductor nanostructures that will eliminate the problem of spatial nonuniformity while retaining the low-cost advantage of thin film manufacturing. The technology is based on electrochemical synthesis of semiconductor nanostructures on a preformed template and is flexible in the choice of semiconductor and substrate materials.     

Injection-voltaic effect based on multilayer semiconductor structures

The analogy between the photovoltaic effect in solar cells and the injection-voltaic effect in the multilayer p-n semiconductor structures is described. The possibility to create a new elemental base of analog and digital electronic devices based on the injection-voltaic effect is demonstrated.     

Effects of compression ratio on the combustion characteristics of a homogeneous charge compression ignition engine

The effects of homogeneous charge compression ignition (HCCI) engine compression ratio on its combustion characteristics were studied experimentally on a modified TY1100 single cylinder engine fueled with dimethyl ether. The results show that dimethyl ether (DME) HCCI engine can work stably and can realize zero nitrogen oxides (NO_x) emission and smokeless combustion under the compression ratio of both 10.7 and 14. The combustion process has obvious two stage combustion characteristics at ɛ = 10.7 (ɛ refers to compression ratio), and the combustion beginning point is decided by the compression temperature, which varies very little with the engine load; the combustion beginning point is closely related to the engine load (concentration of mixture) with the increase in the compression temperature, and it moves forward versus crank angle with the increase in the engine load at ɛ = 14; the combustion durations are shortened with the increase in the engine load under both compression ratios. __________ Translated from Chinese Journal Combustion Engine Engineering, 2006, 27(4): 9–12 [译自: 内燃机工程]     

级联式双反馈风力发电系统建模仿真

提出了一种新型的变速恒频级联式双反馈发电系统.该系统省略了PWM变换器及直流电容.不需要进行频率控制,与常规的双反馈风力发电系统相比,原理简单,控制方便.文章分析了系统变速恒频发电原理.通过对双馈电机的分析建立了该系统稳态运行时的电路模型,并进行了理论分析.在此基础上.利用SIMULINK分别对空载和负载稳态运行进行了仿真.通过对仿真结果分析,给出了该系统发电运行的条件.该系统空载运行时的并网比变速恒频双反馈发电系统空载并网更容易实现.     

一种新型CPC聚光热电联产系统

开发了一种新型热管冷却式CPC聚光热电联产系统(PV/T),建立了系统的数学模型。系统采用了蒸发段截面为半圆形的异形热管冷却,整个系统只有普通平板热水器的大小。CPC聚光器截取后的高度为100mm,入口宽度为62 mm,几何聚光比为4.13。采用了光学模拟软件对聚光器进行了光线追踪模拟与辐照度分析,随着入射角度的减小,光斑向聚光器对称中心偏移,最大能流密度逐渐减小,接收面光线分布趋于均匀,但依然存在光线集中现象。     

Integrated energy systems based on cascade utilization of energy

Focusing on the traditional principle of physical energy utilization, new integration concepts for combined cooling, heating and power (CCHP) system were identified, and corresponding systems were investigated. Furthermore, the principle of cascade utilization of both chemical and physical energy in energy systems with the integration of chemical processes and thermal cycles was introduced, along with a general equation describing the interrelationship among energy levels of substance, Gibbs free energy of chemical reaction and physical energy. On the basis of this principle, a polygeneration system for power and liquid fuel (methanol) production has been presented and investigated. This system innovatively integrates a fresh gas preparation subsystem without composition adjustment process (NA) and a methanol synthesis subsystem with partial-recycle scheme (PR). Meanwhile, a multi-functional energy system (MES) that consumes coal and natural gas as fuels simultaneously, and co-generates methanol and power, has been presented. In the MES, coal and natural gas are utilized synthetically based on the method of dual-fuel reforming, which integrates methane/steam reforming and coal combustion. Compared with conventional energy systems that do not consider cascade utilization of chemical energy, both of these systems provide superior performance, whose energy saving ratio can be as high as 10%–15%. With special attention paid to chemical energy utilization, the integration features of these two systems have been revealed, and the important role that the principle of cascade utilization of both chemical and physical energy plays in system integration has been identified.     

新型半导体制冷空调伞温度场流场的实验研究

针对传统制冷空调伞设备庞大且不节能环保等问题,提出一种小型便携式半导体制冷空调伞,自行搭建用于测试操作参数对新型半导体制冷空调伞温度场和流场影响的实验台,在定环境温度、空气流量和距地高度的实验条件下进行实验研究。实验结果表明,与传统制冷空调伞相比,新型半导体空调伞不仅可营造局域舒适性环境,而且还扩展了制冷系统的应用范围。     

基于能量梯级利用的太阳能冷热联供系统

从能量梯级利用的角度出发，提出了一种新型太阳能冷热联供复合系统。该复合系统可根据太阳辐射强度在不同的季节分别用作单一的太阳能热水器、热泵热水器或太阳能吸附式冷热联供复合系统。建立了相应的数学模型，计算了该系统在不同季节各种典型工况下的性能指标。计算结果表明，该系统不仅可实现冷热联供的双重功能，而且具有较大的节能潜力。