Superheating of Liquid Alkali Metals

The maximum attainable temperature of superheating and the critical temperature of cesium, rubidium, and potassium are correlated using the generalized van der Waals equation of state. This study shows that the maximum attainable temperatures of superheating for liquid cesium, rubidium, and potassium are 1722, 1802, and 2039 K, respectively. The results of the determination of the maximum attainable temperatures of superheating of liquid cesium, rubidium, and potassium are in agreement with experimental data. The given study establishes that liquid cesium, rubidium, and potassium can be superheated up to temperatures of about 200 K below their critical temperatures of 1924, 2017, and 2280 K, respectively. Moreover, cesium, rubidium, and potassium have been found to obey the single-parameter law of corresponding states, with the maximum attainable reduced temperature of superheating as the thermodynamic similarity parameter.     

非自由表面大块Pb晶体的动力学过热模型

主要对Pb-Al试样经差示扫描量热仪DSC-7以不同的加热速度进行加热后得到的测量结果进行分析,从而为进一步完善熔化及过热理论提供了可靠性。     

燃气机热泵改变制冷剂流量的增益调度控制

燃气机热泵可以通过改变燃气机转速调节系统容量,系统容量的调节和压缩机转速的变化,需要电子膨胀阀调节制冷剂流量与之相匹配。采用实验方法建立蒸发器过热度模型,通过理论分析和实验测试,研究了燃气机热泵系统变转速调节和当过热度设定值改变时蒸发器过热度的控制策略。提出采用增益调度控制策略实现蒸发器过热度的控制,实验结果表明:改变燃气机转速时,过热度控制比较精确,波动范围在±0.5℃以内;过热度设定值改变时,最大超调量小于2℃,过热度响应速度快,具有很好的动态响应特性,达到稳态的时间不超过200 s。     

非自由表面大块晶体过热的初探

初步研究了非自由表面大块单晶A1及大块晶体Pb的过热.主要介绍通过有效的方法制得试样,用DSC-7准确测量出在包覆状态下大块单晶Al及大块晶体Pb的过热度,从而得出大块晶体过热的必要条件.     

大型CFB锅炉受热面过热保护

分析了CFB锅炉炉膛内大量蓄热在停炉或停机时对过热器、再热器以及水冷壁造成的危害,比较了各种保护方案,并且提出了适合国情的应对措施。     

Fe-B-Si共晶合金的微观净化及净化机制

采用熔融玻璃与循环过热相结合的净化方法,系统研究了Fe-B-Si共晶合金的净化规律及其净化机制,提出了该合金大体积液态金属获得深过冷的优化工艺,采用该工艺可快速,稳定地使6－70gFe82B17Si1,Fe80.5B15.5Si4,Fe76B12Si12,Fe76B12Si10C2别获得343K、358K、367K和412K大过冷度,并首次成功地制备了Fe76B12Si12及Fe76B12Si10C2合金的块状纳米软磁材料,研究结果表明,净化玻璃的化学成分、循环过热温度及净化过程中熔融玻璃和合金液的良好排气条件是影响净化效果的主要效果。     

Superheating limits of liquid helium I

It is shown that the maximum superheat temperature ΔT_max in liquid helium I, determined under steady-state peak nucleate boiling conditions, cannot be realistically estimated from the thermodynamic limit of superheat (spinodal), as has been previously claimed. It is suggested that a more meaningful estimate of ΔT_max can be obtained from the kinetic limit of super-heat (homogeneous nucleation temperature). Experimental data on the homogeneous nucleation superheat temperature, ΔT_h, in liquid helium I over an extended temperature range are presented and compared with the ΔT_max measurements of several investigators. It is pointed out that in any quantitative predictions of ΔT_max, a knowledge of ΔT_h alone is not sufficient. In fact, the measured value of ΔT_max can lie either below or even above ΔT_h depending on the bath temperature, conditions of the surface, and the thermophysical properties of both heater and liquid.     

20t/h小型带发电半组装锅炉改进设计

介绍小型带发电锅炉存在问题的原因分析及解决办法     

Chemical desulfurization of Turkish Cayirhan lignite with HI using microwave and thermal energy

The purpose of the present work was to investigate the effect of the concentration of HI and reaction time in the chemical desulfurization of Cayirhan lignite in a microwave energy set up and to compare the results with those obtained in a thermal heating system. As the concentration of the HI was increased, the extent of desulfurization was also increased in all the experiments done for all of the samples of lignite. The main difference between the thermal and microwave heating was the extremely short times for desulfurization in the case of microwave experiments. After desulfurization experiments S_total/C ratio of all of the samples decreased to a lower value than that of the raw lignite which was 0.034. The loss of the sulfur containing bands in the FTIR spectra of the desulfurized lignite showed that the HI treatment was effective in the cleavage of dithioethers and thioetheric groups. Sulfur containing functionalities like thioethers and thiols although usually requiring strong reducing agents could be removed in significant amounts with concentrated hydroiodic acid from the coal matrix. The rapidity of the desulfurization reactions with microwave heating in concentrated HI was probably due to localized superheating which made HI more effective in the reactions such as with thioethers and thiols that normally resisted to cleavage by HI under thermal heating conditions.