人工神经网络模拟生物膜滴滤塔废气处理过程

在生物滴滤塔处理有机废气过程中，参数非线性度大，其处理过程适合用人工神经网络(ANN)模拟。通过建立神经网络模拟生物滴滤塔处理有机废气的过程，对遗传算法的改进能够提高其收敛速度，并采用改进遗传算法(MGA)与LMBP算法相结合(MGA—LMBP)，利用已有的实验数据样本训练神经网络，取得了较好的效果。     

生物滴滤塔处理恶臭气体工艺优化试验

采用生物滴滤塔进行了恶臭气体恶臭成分脱除试验,探讨了填料层高度、营养液喷淋量和停留时间对恶臭成分的脱除影响。结果表明,优化工艺条件为:填料层高度500mm,喷淋量为20L/h,停留时间40s。并在此条件下进行了连续运行试验,取得了良好效果。     

液体分布装置出口流型转换实验研究

针对一种液体分布装置,采用可视化方法,对三种工质流过不同开孔规格的液体分布装置时的出口流型转换过程进行了实验研究。研究发现液体分布装置出口流型转换与管间流型转换过程相似,也经历了片状流、柱状流、滴状流以及它们之间的过渡流型。发现液体分布装置的开孔孔径、孔中心距对布液器出口流型转换有较大影响:相同孔中心距下,孔径变大使得流型转换的边界流量变小;而相同孔径下,大孔中心距会使流型转换边界流量变大。开孔规格对柱状流、片状流之间的转换影响相对于其他流型的影响要大。同时给出了液体分布装置出口流型转换的准则关联式。     

螺旋型空气分布器射流特性的实验研究

通过实验研究了螺旋型空气分布器的常温射流特性,进行了不同送风角度条件下,空气分布器射流的包络面、主流区速度分布特性的实验。结果表明,送风射程随着送风风量和送风角度的增加而增大,送风风量对送风宽度的影响不是随着风量的增大而增大或者减小,送风宽度随着扇叶角度的增大而整体呈减小的趋势;使得送风均匀性的扇叶角度在0°~10°。     

抛物柱面聚焦器焦平面上辐射通量分布的理论和实验研究

对抛物柱面聚焦器焦平面上的辐射通量分布作了模拟计算和实验研究。计算时采用经某些改进的“半有限积分法”使之更能反映实际运行情况。实验研究采用摄影法，分别以太阳和月亮为光源的折摄焦平面上的像斑。模拟计算与实验结果比较吻合。     

Experimental investigation of liquid metal alloy based mini-channel heat exchanger for high power electronic devices

There is currently a growing demand for developing efficient techniques for cooling integrated electronic devices with ever increasing heat generation power. To better tackle the high-density heat dissipation difficulty within the limited space, this paper is dedicated to clarify the heat transfer behaviors of the liquid metal flowing in mini-channel exchangers with different geometric configurations. A series of comparative experiments using liquid metal alloy Ga68%In20%Sn12% as coolant were conducted under prescribed mass flow rates in three kinds of heat exchangers with varied geometric sizes. Meanwhile, numerical simulations for the heat exchangers under the same working conditions were also performed which well interpreted the experimental measurements. The simulated heat sources were all cooled down by these three heat dissipation apparatuses and the exchanger with the smallest channel width was found to have the largest mean heat transfer coefficient at all conditions due to its much larger heat transfer area. Further, the present work has also developed a correlation equation for characterizing the Nusselt number depending on Peclet number, which is applicable to the low Peclet number case with constant heat flux in the hydrodynamically developed and thermally developing region in the rectangular channel. This study is expected to provide valuable reference for designing future liquid metal based mini-channel heat exchanger.     

Experimental research on the effects of distributor configuration on flow distribution in plate‐fin heat exchangers

The effects of different distributor configurations on the flow distribution in plate‐fin heat exchangers were studied. It was found that an irrational distributor configuration would lead to the flow maldistribution and a different degree of non‐uniformity of the flow distribution in the transverse and longitudinal directions. The distributor configuration and Reynolds number are the main factors affecting the flow distribution. An improved distributor configuration with a fluid complementary cavity has been brought forward. The experimental results showed that the improved distributor configuration can effectively improve the performance of flow distribution in heat exchangers. The best performance of flow distribution was obtained at h/H = 0.2. The correlations between the flow maldistribution characteristic and the flow Reynolds number for different distributor configurations were deduced according to the experimental data. © 2004 Wiley Periodicals, Inc. Heat Trans Asian Res, 33(6): 402–410, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20023     

C/N值对A/O生物滤池性能影响分析

通过分析C/N值对A/O生物滤池性能的影响,为污水回用提供有效的处理工艺及参数。对模拟污水进行动态试验,研究不同的C/N比值对氨氮、总氮及COD去除效果的影响。试验表明,在当A/O生物滤池C/N比值为4.6~5.5、水力负荷为2~3m/h,回流比为1∶2,好氧段气水比为1∶3时,原水中的NH3-N、TN和COD都得到了较好的去除,去除率最高分别能达到92.1%,92%,95%。A/O生物滤池能够有效地去除污水中的氨氮、总氮及COD等,在适当的C/N比值的情况下,可有效提高去除效率,降低运行成本。     

Numerical investigation on the thermal performance of cross-cocurrent and countercurrent three fluid heat exchanger with flow maldistribution at the inlet

Flow maldistribution at the inlet of a heat exchanger (HX) is a significant parameter that needs to be considered to judge the performance of the same. In this paper, four arrangements of three-fluid cross-flow heat exchanger (3FCFHX) with different flow conditions are considered as shown in Figure 1 in which is the performance of cross-countercurrent and cross-cocurrent arrangements for uniform and flow maldistribution at the inlet. In addition, the effect of different inlet fluid flow models on the HX performance are investigated numerically. Among the three fluids in these arrangements, the central fluid is considered to be the hot fluid. From the principles of conservation of energy, the governing equations for three fluids are generated and solved using the finite element method. Four different inlet fluid-flow models are considered for the analysis. Performance is judged using hot fluid effectiveness and the number of transfer units for a different range of governing parameters. The effects of inlet flow maldistribution (IFM) are measured using degradation factors. The results show that the performance of cross-cocurrent arrangement is found to be superior to the cross-countercurrent arrangement. In addition, the IFM enhances thermal performance. Further, it is determined that the flow maldistribution at the inlet will enhance the hot fluid effectiveness by 4%–4.5% and 1.8%–2% in cross-cocurrent and countercurrent arrangements, respectively. The results give a thorough insight into the significant concerns involved in the design of such HXs. Application of the finite element method proves the ease of determining the exit temperatures of the fluids in the HX. This approach is indeed time-saving and gives insights when compared to the CFD approach.     

Experimental investigation on subcooling of liquid hydrogen by helium gas injection through evacuation

Subcooling is the process of bringing down the temperature of liquids lower than that of the boiling point of the corresponding vapor pressure. The performance of subcooling of cryogenic liquids mainly depends on the heat-inleak of the system, the helium injection mass flow rate, helium injection temperature, and helium injection nozzle pattern. This paper presents an alternative method, by making use of the least heat in the leakage of the liquid hydrogen storage container, which is quite possible because containers with excellent thermal insulation are commercially available nowadays. The process involved is rapid evacuation through gas ejectors, thus reducing the effect of temperature. The advantage and the process of evacuation leading to subcooling in a unique manner are the objective of this article. The experimental results are discussed in comparison with the thermophysical process involved in the subcooling operation. A comparative study is also carried out with the theoretical heat exchange process in which helium is used as a medium for the economy of the stated process. It is stated that the current process of subcooling through evacuation is superior to the conventional heat exchange process.     

Numerical investigation of the impact of two-phase flow maldistribution on PEM fuel cell performance

Flow maldistribution usually happens in PEM fuel cells when using common inlet and exit headers to supply reactant gases to multiple channels. As a result, some channels are flooded with more water and have less air flow while other channels are filled with less water but have excessive air flow. To investigate the impact of two-phase flow maldistribution on PEM fuel cell performance, a Volume of Fluid (VOF) model coupled with a 1D MEA model was employed to simulate two parallel channels. The slug flow pattern is mainly observed in the flow channels under different flow maldistribution conditions, and it significantly increases the gas diffusion layer (GDL) surface water coverage over the whole range of simulated current densities, which directly leads to poor fuel cell performance. Therefore, it is recommended that liquid and gas flow maldistribution in parallel channels should be avoided if possible over the whole range of operation. Increasing the gas stoichiometric flow ratio is not an effective method to mitigate the gas flow maldistribution, but adding a gas inlet resistance to the flow channel is effective in mitigating maldistribution. With a carefully selected value of the flow resistance coefficient, both the fuel cell performance and the gas flow distribution can be significantly improved without causing too much extra pressure drop.     

Experimental investigation of pressurized packing saturator for humid air turbine cycle

Humid air turbine (HAT) cycle is an advanced power generation system, and its efficiency and output power are improved by humidifying the compressed air. This humidification process is completed in the saturator. Therefore, the humidifying performance of saturator has great influence on the performance of HAT cycle. In this work, a new type packing saturator was designed and a series of experiments were carried out to study its humidifying performance. In order to improve the uniformity of the saturator inlet, a twin-tangential annular flow gas distributor was designed. Then it was authorized by China invention patents (ZL201010200778.9). Now, the mal-distribution factor of inlet air is mainly between 0.15 and 0.35 in all experimental conditions. Some key parameters of air and water at the inlet and outlet of saturator were measured at different experimental conditions. These results show the outlet humid air temperature is an important parameter for determining the humidifying amount of the saturator. The humidifying performance of the saturator is mainly affected by the inlet water temperature and the liquid/gas (L/G) ratio. At the same operating pressure, the humidity ratio of outlet humid air increases with inlet water temperature and L/G ratio. At higher inlet water temperature, the L/G ratio has a greater effect on the humidity ratio of outlet humid air. The outlet water temperature is mainly affected by the inlet gas temperature. With the increasing of inlet air temperature, the outlet water temperature increases, and it is close to the wet-bulb temperature of inlet air.     

微纳结构铜表面低液位池沸腾实验研究

采用两步电镀法,在改变电流密度的情况下制备出具有不同微纳结构和润湿特性的A、B两个表面,并应用于低液位饱和池沸腾的实验研究中.通过与铜表面对比,发现两个表面在低热流密度情况下,传热系数要高于铜表面,但液位降低时传热系数提升幅度较小,原因在于铜表面沸腾气泡较大,液位降低气泡脱离有很大影响,而表面A、B沸腾气泡较小,液位降...     

格栅型煤粉分配器的分配特性研究

为了研究格栅型煤粉分配器的均匀分配效果,在分配器入口前加设一段弯管以形成分配器入口气固两相流动的非均匀条件,利用Fluent软件对不同格栅数的煤粉分配器的性能进行数值模拟,得到其内部流动情况以及颗粒运动状态.结果表明:在两级格栅出口转角处磨损严重,在流通截面扩大处磨损较小;每根支管的出口速度都不均匀.随着格栅数增加,各...