微通道流体物性对流动与传热影响的数值模拟和实验研究

针对微矩形通道内单相层流流动和传热特性进行实验研究和三维数值模拟研究.微矩形通道宽为50μ m,高为200μ m,工质采用去离子水.讨论流体热物性随温度变化对流动传热特性的影响.并把实验数据、模拟结果和文献参考值比较.结果显示,恒热流边界条件下,由于热量加入导致流体温度沿流动方向升高,摩擦系数沿流动方向有递减趋鼢势.进口处的Nu数有最大值,在L*=0.2处降到最小值,之后又攀升到充分状态时的Nu数值.在充分发展段,Nu数保持不变.黏性耗散对热起始段的作用不能忽略.     

微纳米曝气技术在水环境治理方面的应用

微纳米曝气是一种新型的人工水体曝气技术,在治理水体污染中具有投资少、见效快的明显优势.在分析微纳米气泡发生装置原理及特点的基础上,结合其在水环境治理中的试验研究,揭示微纳米曝气与常规曝气治污效果的差异,进而对微纳米曝气技术的推广和应用起到宣传作用.     

致密型纳滤膜用于微污染地表水深度处理的中试研究

对于微污染原水,常规工艺处理难以满足出厂水水质要求。考察了致密型纳滤中试装置对微污染地表原水进行深度处理的效果,探索了膜污染机制,优化了膜污染的化学清洗方法。中试结果表明,致密型纳滤系统能高效去除无机盐离子和溶解性有机物,其TOC去除率可达94%,出水电导率降低87%。膜污染主要由无机结垢和有机污染组成,前者主要成分为碳酸钙,后者为多糖和蛋白质。对化学清洗方法的优化结果表明,盐酸(pH=2)结合EDTA(pH=12,5 mmol/L)清洗可以有效恢复膜通量至初始水平。该中试装置运行成本为0.63元/m³,建议在实际运行中,可将膜过滤出水和常规工艺出水进行混合作为供水,以达到降低运行成本且保证供水水质的目的。     

润湿性微纳米圆管中去离子水的流动特征

在传统的流体力学中,流体在固壁处流速为零,即无滑移边界条件。在微纳米条件下,由于固液界面作用力增大,无滑移边界条件不再适用。该文首先从微米石英圆管中的流动实验现象出发,给出润湿性边界黏滞层厚度随应力变化的边界模型。在此基础上推导出层流条件下,微纳米管中的流量公式,并对流量公式进行渐近分析,同时也分析流动微纳米尺度下的流动特征。最后用微米圆管中去离子水的流动实验,对新建的理论模型进行验证。研究表明:润湿性条件下,边界黏滞层厚度随驱动力的增大而减小;新建立的微纳米尺度下的边界模型和流量公式非常符合实验结果,其中一次方的流量模型应用时更为简单,在压力梯度较小时,指数项起作用产生了非线性流动的效果。     

微纳米气泡曝气对泵站放江污染的治理效果研究

泵站放江会导致水体短时间内接受大量污染物,造成河道溶解氧急剧下降,化学需氧量(COD)、总磷(TP)、氨氮(NH3-N)等指标出现不同程度的超标,导致河道黑臭现象的发生.以实际工程为例,在一段受泵站放江影响的河道中进行微纳米气泡曝气,探究微纳米气泡曝气对泵站放江造成的污染物超标现象的影响.结果表明:①泵站放江使得河道水...     

高锰酸钾复合药剂对微污染水中浊度色度强化去除效能的生产性试验研究

在对高锰酸钾复合药剂预处理工艺强化去除水中色度、浊度效果的生产性试验研究中发现：高锰酸钾复合药剂预处理工艺对水中色度、浊度的去除效果理想，对微污染水中色度和浊度的强化去除效果要优于预氯化工艺和聚合氯化铝、聚合硫酸铁混凝工艺。     

风／光/水互补微型电力系统的交直流潮流的研究

农村户用风、光、水互补供电系统项目旨在采用户用互补发电系统解决偏远地区的用电问题。相比于传统的电网架线的方法,具有投资少、技术简单、易于维护、满足可持续发展等显著的优点。由于风能／太阳能发电的特殊情况,需要采用交直流（AC／DC）混合供电模式。针对微型电网电源和电网的特点建立与其适应的潮流算法,根据8节点算例经过4次迭代收敛,各点电压降落维持在要求的范围之内。图5幅,表2个。     

Enhancement of food waste digestion in the hybrid anaerobic solid-liquid system

The hybrid anaerobic solid-liquid (HASL) system is a modified two-phase anaerobic digester for food waste treatment. To enhance the performance of anaerobic digestion in the HASL system, thermal pre-treatment (heating at 150 degrees C for 1 h) and freezing/thawing (freezing for 24 h at-20 degrees C and then thawing for 12 h at 25 degrees C) were proposed for food waste pre-treatment before the anaerobic digestion. Both processes were able to alter the characteristics and structure of food waste favoring substance solubilization, and hence production of methane. However, there was no net energy gain when the energy required by the pre-treatment processes was taken into account.     

Membrane-flocculation-adsorption hybrid system in wastewater treatment: micro and nano size organic matter removal .

Cross flow microfiltration with in-line flocculation reduces the fouling of membranes thus leading to high quality product water. A detailed experimental study conducted with an artificial suspension (particle size distribution similar to that of surface water) revealed that the filtration rate can be increased by several times by adopting in-line flocculation. In-line flocculation-microfiltration is therefore an attractive technique to reduce internal clogging while improving the permeate flux significantly. A detailed ultrafiltration (UF) study was conducted with biologically treated sewage effluent with pretreatment by flocculation and powdered activated carbon adsorption. The TOC removal by the NTR 7410 UF membrane alone was 43.6%. The TOC removal increased significantly by the use of pretreatment: 69.3% by flocculation and 91% by flocculation followed by adsorption. The organic colloidal portion (between 3,500 dalton and 0.45 microm) in the biologically treated effluent was removed up to more than 65% by the pretreatment of flocculation. The molecular weight of the biologically treated effluent ranged from 250 to about 3,573 dalton with the highest fraction in the range of 250-845 dalton. By the incorporation of pretreatment, the majority of both large and small molecular weight organic matter was removed. This hybrid system led to practically no filtration flux decline in membrane filtration.     

Numerical solution of the Saint-Venant equations by an efficient hybrid finite-volume/finite-difference method

A computationally efficient hybrid finite-volume/finite-difference method is proposed for the numerical solution of SaintVenant equations in one-dimensional open channel flows. The method adopts a mass-conservative finite volume discretization for the continuity equation and a semi-implicit finite difference discretization for the dynamic-wave momentum equation. The spatial discretization of the convective flux term in the momentum equation employs an upwind scheme and the water-surface gradient term is discretized using three different schemes. The performance of the numerical method is investigated in terms of efficiency and accuracy using various examples, including steady flow over a bump, dam-break flow over wet and dry downstream channels, wetting and drying in a parabolic bowl, and dam-break floods in laboratory physical models. Numerical solutions from the hybrid method are compared with solutions from a finite volume method along with analytic solutions or experimental measurements. Comparisons demonstrates that the hybrid method is efficient, accurate, and robust in modeling various flow scenarios, including subcritical, supercritical, and transcritical flows. In this method, the QUICK scheme for the surface slope discretization is more accurate and less diffusive than the center difference and the weighted average schemes.     

Evaluation of hybrid processes for nitrification by comparing MBBR/AS and IFAS configurations.

An integrated fixed-film activated sludge (IFAS) pilot plant and a moving bed biofilm reactor coupled with an activated sludge process (MBBR/AS) were operated under different temperatures, carbon loadings and solids retention times (SRTs). These two types of hybrid systems were compared, focusing on the nitrification capacity and the nitrifiers population of the media and suspended biomass alongside other process performances such as carbonaceous and total nitrogen (TN) removal rates. At high temperatures and loadings rates, both processes were fully nitrifying and achieved similarly high carbonaceous removal rates. However, under these conditions, the IFAS configuration performed better in terms of TN removal. Lower temperatures and carbon loadings led to lower carbonaceous removal rates for the MBBR/AS configuration, whereas the IFAS configuration was not affected. However, the nitrification capacity of the IFAS process decreased significantly under these conditions and the MBBR/AS process was more robust in terms of nitrification. Ammonia oxidising bacteria (AOB) and nitrite oxidising bacteria (NOB) population counts accurately reflected the changes in nitrification capacity. However, significantly less NOBs than AOBs were observed, without noticeable nitrite accumulation, suggesting that the characterisation method used was not as sensitive for NOBs and/or that the NOBs had a higher activity than the AOBs.     

铁炭微电解-Fenton试剂氧化-二级A/O工艺处理化工废水工程实例

采用铁炭微电解结合Fenton试剂的化学氧化做预处理,二级A/O结合PACT工艺做后处理,混凝沉淀做辅助处理工艺处理含硝基苯的化工废水。介绍了工艺流程、主要参数和运行效果,同时讨论了该工艺的影响因素。工程监测结果表明:设计进水水量为600im~3/d,COD为5000mg/L时,预处理出水COD降至约1500mg/L,BOD/COD从0.1上升到0.3以上,后处理出水COD约为150mg/L,辅助处理出水COD小于100mg/L,COD总去除率可达97％。该工艺根据废水呈酸性的特点并合理利用废铁刨花,具有以废治废的特点,处理效果好,成本低,操作维护方便。     

Observation of the induced pressure in a hybrid mlcro/nano-channel

This paper studies the flow characteristics in micro/nano-channels subjected to an applied electric field. The nano-channel flow was observed by means of the fluorescence Calcein. A Fluorescence Concentration Gradient Interface (FCGI) was observed across the nano-channel array. The front of the FCGI was shown to have an analogous parabolic shape. The propagation of this interface reflects indirectly the induced pressure at the micro/nano-channel junction, where the enrichment-depletion processes are known to take place. This induced pressure was predicted by numerical simulations, and this paper gives the first experimental evidence.     

曲靖市暴雨洪水特性分析

根据曲靖市的自然地理状况，对全市主要河流按流域分片，结合水文站、雨量站的分布情况，利用实测资料分析片区内暴雨洪水特性，探索暴雨洪水规律，为曲靖市防洪减灾和水资源配置提供科学依据。