红柱石复相陶瓷太阳能热发电输热管的制备及性能

以红柱石为主要原料,采用无压烧结制备了用于太阳能热发电的红柱石复相陶瓷输热管,研究了组成和烧结温度对材料烧结性能和力学性能的影响。利用X射线衍射仪、扫描电子显微镜以及万能试验机表征了样品的物相组成、微观结构和力学性能。结果表明,在1490℃烧结温度下保温2 h获得了性能优良的红柱石复相陶瓷,样品吸水率为0.41%,气孔率为1.10%,体积密度为2.69 g/cm^3,抗折强度达128.78 MPa;经30次抗热震(室温-1100℃,在空气中气冷)测试后,样品的抗折强度为142.55 MPa。XRD、SEM分析结果表明,复相陶瓷的相组成为莫来石、锆英石和α-方石英等,锆英石和α-方石英均布在莫来石的晶粒间,提高了复相陶瓷的机械性能和断裂性能。

圆筒输热管隔热临界半径r_c确定

对于圆筒输热管，其热绝缘性能与绝热层厚度之间的关系，远非象平壁那样呈线性关系。总热阻与绝热层厚度之间的关系并不是单调递增的关系，存在着一个临界绝热半径。如果，绝热层外半径小于临界绝热半径ｒｃ，随着绝热层厚度的增加，总热阻不但不增加，反而减少，导致热损耗增大．只有当绝热层外半径大于临界绝热半径ｒｃ时，总热阻才会随着绝热层厚度的增加而增大，热损耗减少。绝热层才真正发挥绝热作用．至于，绝热层的内半径已大于临界绝热半径，那么，绝热层的绝热保温作用肯定是有效的，否则，是无效的．本文试通过数学推导，导出临界绝热半径ｒｃ大小，以便于在工程换热、农产品加工的生产中起一定指导作用。

高温输热管道保温新技术——介绍复合层保温方法

对于载热介质在500℃左右的高温输热管道(比如火力发电广主蒸汽管道),设计最佳保温结构是保温工作中一项十分重要的工作。本文通过对在成都热电厂主蒸汽管所做的试验结果进行分析,说明复合层保温方法是高温输热管道较好的保温方法,值得在保温工作中推广和应用。

稠油蒸汽引射加热管输技术的现场试验

目前在工业中广泛应用的稠油输送方法各有局限，采油现场中应用的管中管热水伴热输送方法热效率低，投资大，运行成本高。针对这种现状，研究了稠油蒸汽引射加热管输技术。该技术在曙光油田1－31－0152井试验效果较好，具有热效率高，投资少，运行成本低的优点，能够满足超稠油地面长距离恒温输送的要求。

Complementary Pass-Transistor Adiabatic Logic Circuit Using Three-Phase Power Supply

A new low power quasi adiabatic logic,complementary pass transistor adiabatic logic (CPAL),is presented.The CPAL circuit is driven by a new three phase power clock,and its non adiabatic loss on output loads can be effectively reduced by using complementary pass transistor logic and transmission gates.Furthermore,the minimization of the energy consumption can be obtained by choosing the optimal size of bootstrapped nMOS transistors,thus it has more efficient energy transfer and recovery.A three phase power supply generator with a small control logic circuit and a single inductor is proposed.An 8 bit adder based on CPAL is designed and verified.With MOSIS 0 25μm CMOS technology,the CPAL adder consumes only 35% of the dissipated energy of a 2N 2N2P adder and is about 50% of the dissipated energy of a PFAL adder for clock rates ranging from 50 to 200MHz.

Thermogravimetric characteristics and different kinetic models for medical waste composition containing polyvinyl chloride-transfusion tube

Thermogravimetric study of medical transfusion tube （MTT） waste containing polyvinyl chloride （PVC） was carried out using the thermogravimetric analyser （TGA） with N2, at different heating rates of 5, 10, 20, 30, 50 ℃/min. The purpose is to obtain pyrolysis characteristics and kinetic parameters of medical waste. The experimental results indicate that the pyrolysis behavior of the MTT sample is in agreement with its main ingredient of PVC, appearing two stair stepping stages. The influence of the additives in MTT on pyrolysis behavior was also revealed, which could improve MTT pyrolysis at lower temperature in the first stage, and cause obvious unsmoothness and asymmetry of the second DTG peak. Four n-order kinetic models of Coats-Redfern, Ozawa, Kissinger and Freeman-carroll were used to get the kinetic parameters. Furthermore, a novel ＂two-step four-reaction model＂ was established to simulate the whole continuous process. The different methods and the kinetic parameters thus obtained were discussed and compared with each other in literatures. The reasons of deviation among kinetic values were tried to be elucidated. The new established model could more satisfactorily describe the pyrolysis process of MTT, being more mechanistic and conveniently serving for the engineering.

Function chain neural network prediction on heat transfer performance of oscillating heat pipe based on grey relational analysis

As for the factors affecting the heat transfer performance of complex and nonlinear oscillating heat pipe (OHP),grey relational analysis (GRA) was used to deal with the relationship between heat transfer rate of a looped copper-water OHP and charging ratio,inner diameter,inclination angel,heat input,number of turns,and the main influencing factors were defined.Then,forecasting model was obtained by using main influencing factors (such as charging ratio,interior diameter,and inclination angel) as the inputs of function chain neural network.The results show that the relative average error between the predicted and actual value is 4%,which illustrates that the function chain neural network can be applied to predict the performance of OHP accurately.

Study on Heat Dissipater for High-Power Thyristors in Explosion-Proof Shell

A new type water-cooled heat dissipater for multiple high-power thyristors in explosion-proof shell used in coal mine was designed, and then, the numerical computation of the three-dimensional steady-state temperature distributions under different working conditions for cooling core was conducted in order to understand in detail the heat transfer performance. Based on the computation results, the temperature differences and the maximum heat transfer rates were given. These results of the study on the heat dissipater lay a basis for optimising its structure design and guiding its operation.

Dynamic Force Reduction and Heat Transfer Improvement for Horizontal Tubes in Large-Particle Gas-Fluidized Beds

The effects of tube bank configuration on forces and heat transfer were investigated for both two-dimensional and three-dimensional gas fluidized beds. Effective dynamic forces and heat transfer coefficients were measured for several tube bank configurations, and it was found that the average forces are smaller than for a single tube. The heat transfer coefficient can be increased by providing sufficient space for particles to descend around both sides of the tube bank. The results provide useful guidelines for optimizing the configuration of tube banks to achieve high heat transfer coefficients while reducing tube erosion due to dynamic forces.

An Investigation of the Swirling Flow and Heat Transfer in a Duct

This paper presents the results of experiments and numerical simulation of the turbulent swirling flow and heat transfer in a duct.The calculated results are in good agreement with data obtained by measurements.It is found that the swirling flow promotes heat transfer to the wall of the duct;the swirl numbers are dependent upon the vane exit angles of the swirler,distance from the swirler and the duct Reynolds number.But the decay of swirling flow in streamwise direction is related to local Reynolds numbers and is independent of the swirler exit angle.The swirl flow characteristics presented in this paper may be used for engineering purposes.

Investigation of Boiling Heat Transfer of Binary Mixture from Vertical Tube Embedded in Porous Media

Ethanol-water binary mixtures with 7 different mole fractions of ethanol ranging from 0 to 1 were adopted as testing liquids in the experiment. The vertical heating tube was inserted in porous matrix composed of five well sorted glass beads whose diameters range from 0.5 to 4.3 mm. Due to the effect of composition, the trend of combination of vapor bubbles was reduced, resulting in the increase of peak heat flux of binary mixture. With the increase of ethanol mole fraction, 0.5 mm diameter bead had lower value of peak heat flux, while for pure liquid the critical state is difficult to appear. With given diameter of glass bead, there existed an optimum value of mole fraction of ethanol, which was decreased with the increase of bead diameter. A dimensionless heat transfer coefficient was predicted through the introduction of a dimensionless parameter of porous matrix, which agreed with the experimental results satisfactorily.