Pressure Drop and Evaporative Heat Transfer Characteristics of Air-water Bubbling Flow

A new kind of evaporative heat transfer experiment for the cooling process of condensers is conducted. The test coil is immersed in an air-water bubbling layer. The air-water two-phase flow passes through the heating tubes of the coil. Due to the motion of the air bubbles in the water, a thin water film forms on the surface of the heating tubes. As the air bubbles passing by the tubes the water is evaporated into the air. The tubes of coil reject heat to the water film, and the evaporation of the water film then rejects heat to the air bubble stream. This heat transfer mode significantly increases the heat transfer coefficient between tubes and air. The consumption of the power of a water pump can be decreased. Moreover, the airflow rate required is less than that of an air-cooled condenser.The pressure drop of air through air-water bubbling layer and the heat transfer between the tubes and water are experimentally investigated in the paper. The results show that the factors affecting the pressure drop and the heat transfer coefficient involve the pore geometry of sieve plate, the height of the air-water bubbling layer, the air flow rate through the sieve plate and the heat flux of tubes. The heat transfer coefficient between tube and water is two times larger than that of falling film of water on the outer surface of tube.     

Subway Station Plate Evaporative Cooler Heat and Mass Transfer of Falling Film under Gas liquid Cross flow Condition

With the influence of the different gas Reynolds number and liquid Reynolds number on falling film heat and mass transfer of subway station plate evaporative cooler, the experiment was carried out by non contact infrared thermal imaging technology under gas liquid cross flow condition. The results indicated that during the increasing of liquid Reynolds number the thickness of liquid film increased and the temperature difference between liquid film inlet and outlet decreased in determined heating water temperature which weakened the heat transfer of liquid film. However, the increase of liquid Reynolds number strengthened the liquid film turbulence that enhanced heat transfer. Under the synergistic effect of these two factors, there was an optimal liquid Reynolds number which minimize thermal resistance and maximize heat and mass transfer coefficient of liquid film.     

Energy Efficiency of Water Transportation System for Surface Water Source Heat Pump

The forms of water transportation, arrangement and operation of pumps contribute to the water transportation energy consumption, which influences the energy-saving effect of surface water source heat pump. The relation between the pumping height and energy consumption of pumps is found by analyzing the model of pump energy consumption. The concept and calculation of critical pumping height is presented considering the limited rate of system energy efficiency. Based on the principle that the pump power changes with water flow rate, the determination of pumps arrangement of one or two stage pumps is described with a concrete example. The influence of water flow rate on heat pumps and water pumps is analyzed, and the energy efficiency of constant and variable water volume are compared. The operation way of this example is concluded for the optimal system energy efficiency. It is found that there is a critical pumping height for the energy-saving effect of surface water source heat pump compared with the traditional system. Moreover, the operation strategies should be determined by the system optimal model since the energy consumptions proportions of heat pumps and water pumps are variable.     

Spray Characteristics of a Two Phase Air water Nozzle for Indirect Evaporative Cooling

We present a two phase air water nozzle that can be applied to indirect evaporative cooling to improve the heat transfer efficiency of indirect evaporative coolers by improving the uniformity of the water film on the surface of the heat exchanger. The spray characteristics of a nozzle with a fan shaped orifice at various air and water pressure conditions was studied. The spray cone angle, the air water mass flow rate, and the relationship between the mass flow rate and the air water pressure ratio were obtained. The best air water pressure ratio and spray cone angle were also found.     

Numerical Simulation of Natural Ventilation and Thermal Environment in Industrial Plant with Heat Source

Numerical simulation of typical industrial plant was conducted by computational fluid dynamics (CFD) method. The influences of distances between fresh air inlet and ground on thermal environment and distribution of pollutant concentration in working zone were discussed when the heat source intensity and pollutant source were fixed. The main features of industrial plant with heat source were analyzed. The air velocity in working zone and the radiation between the wall surfaces should be considered for comprehensive evaluation of the thermal environment of industrial plant. Heat stress index, HSI, was introduced as thermal index to evaluate the thermal environment. Results showed that lifted fresh air inlet was not only helpful to increase the ventilation rate and the air velocity which improve the thermal environment in working zone, but also to decrease the mean pollutant emission concentration in the plant. When the distances between fresh air inlet and ground increased, the ventilation rate and the air velocity in working zone increased and the HIS and pollutant concentration decreased. When the distances between fresh air inlet and ground exceeded 1.2 m, the ventilation rate and the air velocity in working zone tended to be constant.     

Penetration behavior of bath induced by top-blown gas jets for steelmaking converter

The cavity induced by top-blow gas jets impinging on the bath surface is one of most important parameters, which has overwhelming influence on the rate of slag formation and metallurgical performance. Water model experiments are conducted through a 1/10 scaled-down top-blown convertor. Effects of lance height and gas flow rate on penetration behavior are studied, and also the influence mechanism of liquid surface tension on penetration depth is addressed based on the experiments and theory analysis. An energy utilization index (EUI) is defined to reflect how much the impinging kinetic energy of gas jets are transferred into bath for formation of cavity, and an improved model is proposed to predict penetration depth of jets. The results show that penetration depth increases with lowering lance height and increasing gas flow rate, and impact diameter increases with increasing lance height, but is little affected by gas flow rate. Influence of liquid surface tension on penetration depth is enhanced with increasing surface tension and penetration depth. The EUI increases with increasing lance height, and a function relationship of it with lance height is obtained based on the experiments.     

栽植密度对毛白杨无性系生长性状遗传变异的影响

为了选择最适栽培品种及栽培措施,通过毛白杨无性系区域化密度栽培试验（以4个无性系和7种栽植密度采用完全随机区组设计,以河北威县营造的试验林为研究对象）,揭示密度对无性系生长的作用规律。结果表明：从造林当年开始,树高、胸径在无性系间就具有显著差异,S86和BT17无性系明显优于1316和B331无性系;密度对胸径生长的显著影响在造林后2年出现,且显著程度随林龄增大而增大,密度对树高生长的影响在造林后2~3年差异最大;密度×无性系互作对4年生林分胸径、树高的影响不显著;833株/hm2是4个无性系密植的最小底线,高于该密度无性系对胸径的影响,随林龄和密度增大而减小,低于该密度随林龄增大而增大、随密度减小而降低;高密度下无性系对树高的影响随林龄增大或密度减小呈先降低后增大趋势,低密度下随林龄增大呈先增后降趋势;无性系对胸径遗传变异系数的影响在密度间差异不大,无性系×区组互作变异系数及基因型内株间变异系数2年生前在密度间差异较大;无性系×区组互作对树高遗传变异系数的影响随年龄增大呈先增后减趋势,而树高在株间的变异系数随年龄增大而增大;以无性系均值计算的树高广义遗传力在密度间不显著,以单株值计算的树高广义遗传力在密度间差异显著,而2种方式计算的胸径广义遗传力在密度间差异均极显著,在年龄间差异均不显著。     

玉米秸秆还田对小麦根部病害化感作用的模拟研究

在不同时期提取玉米秸秆腐解液,并通过测定其对小麦种子萌发、幼苗株高、茎叶干重、根干重等生长指标及对小麦纹枯病、全蚀病、根腐病病原菌的影响,室内模拟研究了还田玉米秸秆对小麦根部病害的化感作用。结果表明玉米秸秆腐解液对小麦种子萌发、根干重均具有抑制作用,且随腐解液浓度增加抑制作用增强,高浓度腐解液对小麦幼苗株高、茎叶干重的抑制作用较强。小麦根系活力随玉米秸秆腐解液浓度增高而降低,不同时期提取的腐解液对三种小麦根病病原菌菌丝生长具有不同程度的抑制作用。     

Visual Experiments on Bubble Growth and Departure at the Open Tip of Two Capillary Tubes Connected with a Gas Chamber

The bubble growth and departure at the open tip of two capillary tubes joined with a gas chamber was investigated by using a high-speed video imaging system. The experimental results showed that the capillary tube with larger size and hydrophilic property act as the liquid flow channel while the one with smaller size and hydrophobic property as the gas flow channel when liquid submerged the tip of the two capillary tubes without internal gas flow. In contrast, the larger capillary tube become a gas flow channel and the smaller one a liquid flow channel when liquid submerges the tip of the two capillary tubes with internal gas flow. The bubble departure period significantly decreases and the bubble departure diameter eeps in gentle increase with the increase of the flow rate of gas injected into the gas chamber. The liquid flow rate in test section has a significant effect on the bubble growth and departure. A larger liquid flow rate led to a higher bubble departure frequency and a larger bubble departure diameter. At a larger liquid flow rate, the bubble growth and departure at the tip of the upstream capillary become faster, which result in the liquid return at the tip of the downstream capillary tube.     

贵州杂交水稻组合农艺性状与耐冷性的相关及通径分析

为了揭示杂交水稻农艺性状对耐冷性的影响的相对重要性,同时分析农艺性状间的相互关系,为育种家提供理论依据。利用相关区域试验数据,通过采用相关分析和通径分析的方法,研究了16个水稻新组合的全生育期、株高、有效穗、穗长、每穗总粒数、结实率、千粒重、产量和耐冷性之间的关系。相关分析表明：全生育期、株高与耐冷性之间密切相关,均达极显著水平,其中全生育期影响最大,r=0.436;通径分析表明：全生育期、株高与杂交水稻耐冷性有着直接作用。相关分析与通径分析结果一致,生育期较长、株高较高的组合具有较好的耐冷性。     

The Influence of Width of Flag-type Inserts on the Forced Convection of Oil in a Tube

Experimental study of forced convection heat transfer in a horizontal circulartube with ladder-shaped flag-type insert is performed to investigate the characteristics of fluid flow ,heat transfer and the influence of width of flag insert.The working fluid is 30# turbine oil.Theresult shows that the increase of W/D causes the increase of heat transfer coefficient and resistanceforce of fluid flow. The heat transfer coefficient can be enhanced mainly within the length of ninetimes of inner diameter of tube for oil.In the range of experiment, the value of creteria to evaluatethe combined effect is between 1.13 and 1.59.     

脱落酸与赤霉素对瓜尔豆叶片光合作用及内源激素的影响

通过大田随机区组试验设计,在管理、密度、肥水等条件一致的情况下,在瓜尔豆始花期、盛花期、盛荚期和鼓粒期叶面喷施不同浓度的脱落酸与赤霉素,研究其对瓜尔豆叶片光合作用及内源激素的影响,旨在为利用植物生长调节剂对瓜尔豆的高产栽培提供理论依据。试验结果表明,不同浓度的脱落酸处理均能在各个生育时期降低植株叶片的净光合速率和蒸腾速率,关闭气孔,从而抑制其光合作用;而不同浓度的赤霉素处理能明显地增加植株叶片的净光合速率和蒸腾速率,促进其光合作用;脱落酸与赤霉素处理均能降低叶片叶绿体含量,并且赤霉素处理降低更显著。不同浓度的脱落酸处理降低了植株叶片内源吲哚乙酸、赤霉素和激动素的含量,升高了内源脱落酸的含量;而不同浓度的赤霉素处理增加了植株叶片内源吲哚乙酸、赤霉素和激动素的含量,降低了脱落酸的含量,在调节激素动态平衡的基础上对植株进行调控。     

红小豆根系水浸提液对4种受体作物的化感作用

为选择适合红小豆的接茬作物,采用室内培养皿生物测定方法,对不同浓度的红小豆根系水提液下红小豆、萝卜、白菜、小麦的化感效应进行了研究。结果表明：红小豆水提液对自身种子发芽率、发芽指数具有极强的化感抑制作用;随着红小豆根系水提液浓度的增大,3 种受体作物的种子发芽率和发芽指数均呈现降低趋势;从幼苗的根长、幼叶长、侧根数、株高及鲜质量等形态指标上来看,只有小麦随着红小豆根系水提液浓度的增大呈现出促进作用,其余2 种受体作物均呈现出抑制作用,但这种抑制作用在低浓度下差异不显著;萝卜、小麦的SOD、POD活性随着红小豆根系水提液浓度的增大而增强,但白菜的2 种酶活性呈现出下降趋势;小麦、萝卜幼苗的MDA含量表现出降低,白菜MDA含量却显著增加。说明受体作物小麦可作为红小豆的轮作作物、萝卜在与红小豆轮作方面也有着很大的应用潜力。     

Load dynamic matching of supply and demand side based on the utilization of urban sewage heat energy

Flowing dynamic characteristics and its temperature dynamic characteristics of a three-level sewage pipe network in Chongqing were analyzed. A mall's building whole year load was simulated. In the adverse condition of wastewater flow, the market construction peak discharge heat was compared with the sewage heat load, the balance between the most adverse flow and the building demand was found. Explored supply and demand matching method between urban sewage and city building load in flow adverse condition to take full advantage of the urban sewage cold and hot resources. the composite system was adeptcd to make up the most unfavorable flow time of sewage average heat load and the construction load difference; it also puts forward principle of load sharing and control strategy aimed at compound system.     

硅肥对高粱产量、光合速率以及抗折力影响的研究

通过不同时期喷施硅肥,研究硅肥对高粱产量、光合速率及抗折力的影响,为硅肥在高粱上的推广应用提供科学依据。试验选用"归来"牌液体硅肥,采取随机区组设计,共设3个处理,每个处理3次重复。研究结果表明:喷施硅肥具有提高高粱净光合速率、叶绿素含量的作用,可以降低重心高度提高茎秆抗折力,提高高粱籽粒中淀粉、蛋白质、脂肪含量,其中以高粱10片叶时期喷施硅肥效果最好。     

熟化污泥施用对滨海盐渍土绿化植物光合生理特征的影响

滨海盐渍土的高盐碱特性使得植物定植和生长均受到影响,滨海植被极易退化。在上海浦东盐渍土开展不同比例熟化污泥施用改土试验,并通过定期测定种植的常见绿化植物的光合生理,反映污泥施用效应差异及时间上的变化。结果表明：（1）熟化污泥施用盐渍土可提升绿化植物的光合效率。污泥施用综合效果不仅与施用浓度相关,且与植物生长特性有关,同时污泥施用效果持续时间与施用浓度存在正相关。（2）植物种植早期污泥施用可能造成轻度胁迫效应,而夹竹桃、海桐等适应性较强植物早期施用较低浓度（质量比5%以下）污泥即表现净光合速率提升效应;在植物进入正常生长阶段后,大部分植物中低比例（质量比2.5%和5.0%）污泥施用的提升效应更显著;在施用污泥500天左右中低浓度施用比例效应显著下降,此时高浓度(7.5%)施用组仍存在提升效应。建议污泥施用应以低浓度多次施用方法进行。（3）而施用污泥组的气孔导度、胞间二氧化碳浓度均高于对照组,但其净光合速率仍显著低于对照组植株。5%污泥施用180天后新优植物光合效率无明显变化。（4）在较长时间尺度上植物自身适应性是决定污泥施用后净光合速率变化的主导因素,而不同污泥施用量的影响作用在短时效应上较显著。建议在污泥资源化用于滨海盐渍土改良过程中,以5%及以下熟化污泥的中等施用比例为主。     

Influence numerical analysis of combustion chamber thermal boundary conditions on unsteady combustion characteristics in micro ICE

To research the influence of combustion chamber thermal boundary conditions on micro combustion characteristics in micro ICE, the laminar flow finite rate model is adopted to simulate the micro combustion process. Firstly, the influence of grid scale, the time step length and the maximum iterations per time step on accuracy of simulation results are explored. The results show that simulation results agree well with experimental results. And then, the influences of heat transfer coefficient, wall thickness and material on combustion characteristics are discussed. The results indicate that heat transfer coefficient has obvious influence on combustion characteristics. The pressure rise rate decreases, the ignition delays and the highest pressure value drops 2 atmospheres as heat transfer coefficient increases from 0 to 55 W/(m 2·K). The wall thickness and material have a little effect on combustion characteristics. This is because that the main heat transfer resistance in the heat flow path from cylinder to external environment lies between the outer wall and environment.     

Water Environment Carrying Capacity of New Zhengdong District in Zhengzhou City

Taking sections of the Dongfeng Canal, the Xionger River and the Wei River in New Zhengdong District for example, this paper applied water environment capacity to analyze the carrying capacity of surface water environment in the east development zone of the city. The analysis shows that carrying capacity of surface water environment in the study area is not good, carrying capacity of 3 studied waters for TP, BOD_5 and COD is approaching to the limit. New Zhengdong District, in terms of industrial structure, should promote the projects with less water consumption, less or no discharge of wastewater, and also should enhance the sewage treatment, improve recycling rate of the reclaimed water, and reduce the negative impact of sewage and pollutant discharge on environment.     

土壤无机氮解吸特性和菜稻轮作对田间渗漏水硝态氮浓度的影响

通过四季豆-瓢瓜-早稻轮作制不同氮肥用量的3年定位田间试验,探讨土壤无机氮解吸特性和模拟模型,解吸特征值和菜稻轮作对田间渗漏水硝态氮浓度的影响。结果表明,由于土壤无机氮存在形态较简单,解吸过程满足 (0相似文献   

Surveying the relations among traits affecting seed yield in sesame (<Emphasis Type="Italic">Sesamum indicum</Emphasis> L.)

To determine the most important traits influencing seed yield of sesame, 18 lines were evaluated in a randomized block design with three replicates in two years during the 2013 and 2014 growing seasons. Following a combined analysis of variance, multivariate statistical analyses such as simple correlation coefficients, factor analysis, stepwise analysis, path analysis, and cluster analysis were administered on combined means. The correlation coefficient analysis showed a significant negative correlation between seed yield and number of capsules per plant and number of seeds per capsule. Correlation between germination period and seed yield was positive and significant at 5% probability level. Factor analysis divided the 14 measured variables into five factors. In the stepwise regression analysis for seed yield as the independent variable, four traits including number of capsules per plant, first capsule height, number of seeds per capsule, and stem length to first capsule were entered into the regression model in four steps with r² =0.72. The regression coefficient of number of capsules per plant, number of seeds per capsule, and stem length to first capsule were negative and the regression coefficient of the first capsule height was positive and significant at the 5% probability level. The path coefficient analysis based on seed yield as a dependent variable implicated that the number of seeds per capsule had the highest negative direct effect on seed yield. The highest negative indirect effect on seed yield was related to the number of capsules per plant through the number of seeds per capsule. Cluster analysis using Ward’s method divided 18 investigated lines into five clusters.