干旱区平原水库水面蒸发消减研究综述

蒸发强烈、降水稀少是造成西北干旱、半干旱地区平原水库水量损失的重要因素,它严重限制了水库效益的最大发挥,使当地严重短缺的水资源形势变得更加严峻。针对消减水面蒸发技术问题,根据国内外消减水面蒸发研究最新进展,分别对铺洒化学试剂法、种植水生植物法、物理材料覆盖法、风障技术法4类消减水面蒸发的方法进行了概述,对各技术方法中所存在的问题进行了分析和讨论,并对未来消减蒸发实验研究提出了相应的建议,以期为后续实验研究提供参考。     

适用于干旱区的水分蒸发抑制剂研究

为推动水分蒸发抑制剂在南疆平原水库的应用,以十八醇(C_(18)OH)和短链醇正丁醇(C_4OH)为分子膜基材,采用超声波分散技术,制备了水分蒸发抑制剂体系。探讨了不同材料配比、表面浓度、温度、持续时间对抑制效果的影响。研究结果表明:C_(18)OH/C_4OH乳液体系的抑制率较高,抑制剂在试验小区使用时间可达180 h,且抑制水分蒸发的性能十分稳定,抗温度及杂质的干扰能力强,适用于南疆昼夜温差大、易起沙尘的环境。     

CHARACTERISTICS OF THE INTERANNUAL AND INTERDECADAL TIMESCALES OF EVAPORATION IN NORTHERN CHINA IN THE RECENT 115 YEARS

1. INTRODUCTION To calculate long-term average, total evaporation is considered to be equal to precipitation and has key effects on the global water balance [1]. In recent years, several studies on climatic changes with respect toevaporation were carried …     

灰关联分析与多元线性回归模型联合应用研究

依据50年(1954~2003)和田绿洲的气象资料,应用灰关联分析,发现影响绿洲蒸发能力的主要因子是相对湿度与平均气温;在此基础上建立了回归模型。该模型模拟预测绿洲蒸发能力的变化精度较高,但需进一步改进。这种途径比逐步回归分析减少了分析工作量和上机时间。     

防渗墙作用下堤防保护区地下水动态数值模拟分析工：模型、参数及分析方法

介绍了能够考虑水文气象过程的饱和非饱和非稳定地下水流运动数学模型。以全封闭和半封闭式防渗墙为重点研究埘象，以长江重要堤防为背景概化得到典型二元和多元结构堤基、堤身断面及土层的饱和非饱和渗流参数；以实测资料为基础概化得到较典型的水文气象过程，提出降雨入渗和蒸发排泄边界处理方式以及初始条件确定方法；提出根据二维模型模拟结果用有无对比法分析防渗墙对地下水动态的影响，根据三维模型模拟结果分析防渗墙端部绕渗对地下水流场动态的影响。模型和参数具有典型性，研究方法合理、有效。     

国家科技攻关与我国水利水电事业的发展

20世纪70年代初，国家科委和水利电力部把水电工程建设的关键技术难题列为国家科研计划项目，从此，通过“五五”、“六五”、“七五”、“八五”、“九五”5次科技攻关，我国筑坝技术取得了很大发展。攻关科技成果在碾压混凝土坝、面板堆石坝及高拱坝中的应用，以及MgO混凝土筑坝技术，水轮发电机循环蒸发冷却技术，抽水蓄能电站建设技术等都取得了重大进展。     

Special Features of Phosphatizing in Stage Evaporation

High-duty drum boilers (15.5 MPa in the drum) in Russia often function with double-stage evaporation, the first stage occurring in the drum and the second stage occurring in remote cyclones or end compartments of the drum connected to an individual circulation center. This process is accompanied by enhanced introduction of PO₄ phosphates that contaminate the heating surfaces, i.e., waterwall pipes of the boiler, and cause their corrosion under scale, which requires frequent acid cleanings (3 – 4 times a year). The experience of the Novosibirsk TÉTs-5 cogeneration plant employing single-stage evaporation and periodic introduction of phosphates at the expense of higher hardness of the feed and boiler water (as a result of worsening of the feed water) has shown that it is possible to increase the period between boiler cleanings to over ten years with periodic control of the sediment on the pipes by cutting specimens. The annual amount of introduced phosphates is 0.05 – 0.08 mg/dm³. The growth of sediment has virtually stopped in the last three years. The pipes are not damaged. Under conventional water chemistry and transfer of boilers with double-stage evaporation to a single-stage evaporation mode (by elimination of partitions in intradrum compartments of the second stage at the drum ends) the concentration of phosphates in the bleed water has decreased by more than a factor of 4.     

Coefficients of heat and mass transfer of current-technology sprinklers for process computations of cooling towers

Analysis of formulas for computing coefficients of heat and mass transfer derived on the basis of results of laboratory tests of 22 sprinklers is used to show that the classification of sprinklers into film and drop ones can be based on a physically grounded parameter m, i.e., the exponent in the formula for the evaporation number K _ev = A _pλ^m (or for the Merkel number Me = A _xλ^m). Ageneralized formula describing the dependence of the coefficients of heat and mass transfer on the height of the sprinkler is derived, which makes it possible to determine the optimum sprinkler height in cooling tower design. The accuracy of the formulas for computing the coefficients is confirmed by a comparison of experimental and computed values of the temperature of cooled water in the cooling tower of the Novo-Ryazanskaya cogeneration plant. __________ Translated from élektricheskie Stantsii, No. 2, February 2006, pp. 24–30.     

控制蒸发是解决华北地区缺水的第一要务

华北地区严重缺水,但同时因蒸发浪费了大量水资源,以海河流域为例,地表水加地下水仅占总降水资源量的16％,而蒸散发量占总降水量的84％；通过对蒸发的干预和控制,如降低降雨后土壤水分、修建地下水库和回灌地下水,可以节省大量的水资源,控制蒸发是解决华北地区缺水问题的第一要务.     

西南干热河谷降水蒸发变化趋势分析

应用Mann-Kendall和Spearman非参数趋势检验法对45 a西南干热河谷的雨季、枯季和年值降水、蒸发的变化趋势进行了显著性检验,在此基础上,应用基于分形理论的R/S方法对干热河谷未来降水和蒸发的变化趋势进行了预测分析。结果表明:45 a来,西南干热河谷降水变化主要呈上升趋势,趋势性强度以枯季—全年—雨季尺度递减,其中元谋站枯季和道街坝站年值变化显著,而蒸发总体呈十分显著的下降趋势,其中元谋站变化异常显著;未来一定时期内,干热河谷区内降水和蒸发的变化总体上均表现出较强持续性,即降水继续呈上升趋势,蒸发继续呈下降趋势,表明干热河谷区的降水和蒸发可能正朝向有利于人类生存和资源利用的良性方向发展。