冰箱用铜铝管接头的储能焊

本文介绍了冰箱铜铝管接头的性能要求,简述了 PW—1焊机的工艺过程和特点,主要焊接参数的控制方法和效果,列举了由该焊机所焊铜铝管接头的各项性能,并结合对接头的进一步分析及在生产线上的实际应用,提出 PW—1焊机的应用前景.     

催化三旋改用PDC旋风管效果显著

介绍了催化裂化三旋用无泄料盘的ＰＤＣ型旋风管的特点，及用ＰＤＣ型旋风管代替ＶＲＥ型旋风管后收到的显著的经济效益。     

微粒电解二氧化锰电性能及应用

通过化学分析、物理检验及干电池放电等方法研究了微粒电解二氧化锰（ＣＥＭＤ）特性，并讨论了ＣＥＭＤ的电性能及与低活性ＮＭＤ搭配使用效果     

高级氧化技术降解有机选矿药剂的研究进展

残留有难降解有机浮选药剂的选矿厂废水直接排放会污染环境，回用于磨矿或浮选流程会影响分选指标，高级氧化技术是一种有前景的水处理技术。为促进高级氧化技术在此类废水处理中的应用，系统介绍了臭氧及其复合氧化技术、Fenton氧化法、光化学氧化法、光催化氧化法、电催化氧化法及过硫酸盐氧化法降解有机选矿药剂的降解效率、工艺原理等方面的研究结果，并对高级氧化技术处理选矿废水的应用前景进行展望。     

Discharge coefficients of CFVN predicted for high Reynolds numbers based on low-Re-calibration

In 2016, PTB introduced a function for the representation of the discharge coefficient c_D of critical flow venturi nozzles (CFVN) (versus the Reynolds number Re) which covers the operating range for both laminar and turbulent boundary layers. It contains the parameters a for the impact of the core flow, b_lam for the Re-dependency in case of laminar and b_turb in case of turbulent boundary layers. These parameters are not independent from each other but have the fixed relation of b_turb = 0.003654b_lam^1.736.Furthermore, the parameter a and the parameter b_lam are both direct functions of the local curvature radius R_c,throat of the nozzle at the throat. These relationships to R_c,throat are described by theoretical models. Consequently, the overall dependency of the discharge coefficient c_D on Reynolds number Re can be derived from only one parameter.The paper describes how these relationships can be used to extrapolate the calibration values of a CFVN determined with atmospheric air to high pressure gas flow applications covering a Reynolds range of about 1:60. It is shown in detail by examples and the reliability is demonstrated by comparison data for low and high pressure for 33 nozzles. Finally, aspects of preconditions for such extrapolation and uncertainties are discussed.     

A method for correcting discharge of boat-mounted ADCP measurements

GPS data are usually used to measure boat velocity during boat-mounted acoustic Doppler current profiler (ADCP) measurements when bottom tracking is biased by moving bed. GPS cannot provide consistently accurate boat velocity reference because of multipath errors, satellite signal reception problems, and heading errors. In addition, the computation of water velocity from an ADCP mounted onto a moving boat is a vector-algebra problem, thus the discharge calculation is subject to the compass error when GPS is used for boat velocity reference. This paper proposes a method for correcting discharge based on the idea that the discharge calculation is independent of the boat path. The processing of two sets of boat-mounted ADCP measurements integrated with differential GPS and non-differential GPS was simulated to verify the method. The results show that the proposed method performs well in both differential and non-differential GPS conditions. The relative errors range from 0.1% to 1.5% for all measurements with the mean relative errors of 0.7%. Analytical assessment of the GPS errors shows the proposed method is insensitive to the positioning accuracy of GPS, but positioning error of non-differential GPS may induce relative discharge error of more than 1% when the river or stream is narrow. On the contrary, a relatively small compass or heading error can cause a significant error in water velocity and discharge when using GPS as the boat velocity reference. Therefore, integrating a differential GPS and maintaining a slow boat speed are best practices for discharge measurement, especially for narrow streams or short boat paths.     

Effect of polyaniline on hydrogen absorption–desorption properties and discharge capacity of AB3 alloy

A series of AB₃/PANI composites were prepared by adding polyaniline (PANI) into La_0.7Mg_0.25Ti_0.05Ni_2.975Co_0.525 (AB₃) hydrogen storage alloy, which was prepared by magnetic levitation melting, and the composites were investigated by XRD and SEM. The effects of PANI concentration on the hydrogen absorption–desorption properties and discharge capacities of AB₃ alloy were systematically studied by P–C–T isotherms and LAND battery test system, respectively. The results indicated that the addition of PANI did not change the hydrogen absorption capacity of AB₃ alloy distinctly, while the hydrogen desorption plateau pressure of AB₃ alloy decreased firstly, and then increased with the increase in the PANI concentration, the minimum plateau pressures of 0.022, 0.1, 0.321 and 0.55 MPa were obtained with PANI concentration of 2 wt% at 25, 50, 80 and 100 °C, respectively. It was theoretically verified by the changes in enthalpy and entropy of AB₃/PANI hydrides dehydrogenation which were calculated by Van’t Hoff equation. In the present paper, the phenomenon that PANI improved the hydrogen absorption kinetics of AB₃ alloy was found; the influence of PANI concentration on hydrogen absorption kinetics of AB₃ alloy was more apparent at higher temperature. The activation energies of dissolved hydrogen in AB₃/PANI hydrides were calculated from hydrogen absorption kinetics and the Arrhenius equation. LAND experiments demonstrated that, the AB₃/PANI electrodes composites possessed higher cycling discharge capacity retention rates than AB₃ electrode alloy.     

Simple and fast synthesis of LiFePO4-C composite for lithium rechargeable batteries by ball-milling and microwave heating

A very simple and rapid method for synthesizing LiFePO₄-C composite has been developed by vibrant type ball-milling for 30 min and microwave heating for 2–4 min. X-ray diffraction and Mössbauer spectroscopy verify that well-crystallized LiFePO₄ without Fe³⁺ impurities is obtained. From laser particle size analysis and transmission electron microscopy, it is confirmed that a LiFePO₄-C composite with fine and uniform particle size (mean particle size ≤0.640 μm, D75 in volume distribution ≤0.592 μm) and with extremely uniform carbon distribution is prepared by vibrant type ball-milling and microwave heating. The LiFePO₄-C delivers a high initial discharge capacity of 161 mAh g⁻¹ at C/10 and shows very stable cycling behaviour.     

An experimental study on oil discharge ratio at inverter-driven high shell pressure scroll compressor using R410A/PVE

In this study, the oil discharge characteristics of a high shell pressure scroll compressor, which uses R410A as the refrigerant and PVE as the oil, were measured according to the conditions for oil management. The measurement of oil discharge ratio (ODR) in the system is very important to secure the operational reliability. It was made in real time through the refractive index sensor. ODR was greatly influenced by the mass flow rate and the dynamic viscosity of the refrigerant. As the rotation frequency of the compressor became higher, ODR increased rapidly. ODR at 120 Hz was 4.22 times higher than that at 60 Hz. At the same rotation frequency of the compressor, the increase of the suction pressure also played a role in increasing the ODR. In addition, in the zone where the ODR increased rapidly, the compressing efficiency of the compressor decreased significantly.     

Prefabricated and electrical vertical drains for consolidation of soft clay

The use of prefabricated vertical drains to consolidate soft clay is a common ground improvement method. In large projects laboratory testing of PVDs for selection and quality assurance is considered important. This paper presents a review of PVD laboratory testing. The need to provide simulated site conditions in the test is emphasized. In addition instrumented PVDs show that installation stresses in deep soft clay deposits could cause filter rupture under tensile failure. It is also shown that the maximum required discharge capacity of a PVD is obtained by equating the flow rate of the PVD under the installation and consolidation states to the maximum rate of volume reduction of the influential clay cylinder of the PVD. Consolidation can be enhanced much faster in clay soils if vertical drains manufactured with conducting polymer are used. Some laboratory tests, field tests and field applications of such electric vertical drains (EVD) are presented. A minimum current density at appropriate applied voltage is required to benefit from the electric osmosis (EO) application. EVD in dewatering clay soils, extracting heavy metals in clay soils and few other geotechnical applications are also presented.