首届中国清洁技术投融资峰会在北京举行

随着中国经济的飞速发展,能源短缺,环境污染等问题日益严重.欧美等发达国家早已开始着手解决这些问题,每年都有大量来自于政府、企业和风险投资的资金用于清洁技术的研究与应用.根据道琼斯数据显示,2007年在清洁技术领域,全球共发生了221项投资案例,投资总额达30亿美元,比2006年增长了43%.     

中国科技部长万钢获国际氢能大奖

第十七届世界国际氢能大会于2008年6月15日～19日在澳大利亚布里斯班市举行,来自全世界44个国家的600余位代表聚集一堂,讨论当代氧能技术和发展趋势.     

Experimental Investigation on the Adiabatic Film Effectiveness for Counter-Inclined Simple and Laid-Back Film-Holes of Leading Edge

The adiabatic film effectivenessηof the counter-inclined film-holes fed by varying internal coolant intake on the turbine vane leading edge model was experimentally investigated.A semi-cylinder model was adopted to model the vane leading edge which was arranged with two-row holes,which located at±15°on both sides.The four Leading edge model with the combinations of hole-shape(simple holes and laid-back holes)and intake structure(plenum and impingement)were tested under four blowing ratios M of 0.5,1.0,1.5,and 2.0.Theηcontours were obtained by the transient measurement technique based on double thermochromic liquid-crystals.The results present that theηis sensitive to the M for the four studied leading edge cases.The addition of impingement enhances theηfor the two studied holes.The film jets make the coolant-flow closed to the target surface,resulting in higherηunder lower M.The core with higherηappears in the downstream area of hole-exit.Theηenhancement can be provided to almost the identical level by adding the impingement-holes and improving the hole-exit shaping in most areas.With increasing M,the jets with stronger exit normal momentum penetrate into the main-flow.The impingement addition may be a more effective program to upgrade theηrelatively to the exit shaping under larger M.Besides,the laid-back holes with impingement case produce the highest film cooling performance among the four cases,providing great potential in the leading edge especially under larger M.     

国家发展改革委、财政部、国家电监会要求各地限期全面落实差别电价政策

经国务院批准,国家发展改革委、财政部、国家电监会近日联合下发了《关于进一步贯彻落实差别电价政策有关问题的通知》(以下简称《通知》),要求各地限期全面落实差别电价政策.     

热泵辅助太阳能中央热水系统年运行特性研究

提出采用热泵来取代传统的电加热器,构成热泵辅助太阳能中央热水系统,可有效地降低能源消耗.结合2005年西安地区气象数据,建立了合适的数学模型,并用现有的试验数据对模型进行了校准,通过模型模拟了该年热泵辅助和电辅助太阳能中央热水系统的性能系数,输入功耗,出水温度等运行参数,并对两者进行了对比.     

第二讲认识太阳利用太阳

一、太阳与太阳能 众所周知,在浩翰的宇宙中有一颗离我们最近的恒星--太阳.现代科学表明太阳距离我们相当遥远,达到1.5亿km,虽然太阳光的传播速度为30万km/s,但我们在地球上所见到的光线已经是8min之前从太阳发出的光线了.太阳的直径为139万km,而地球直径仅为1.27万km,太阳的直径约为地球直径的109倍,其体积则比地球大130多万倍.尽管如此,由于距离遥远,太阳张角仅仅为32′.     

Numerical Study of Convective and Radiation Heat Transfer Characteristics in an Upward-Facing Cylindrical Cavity under Back-Side Windy Condition

Under the back-side windy condition,the convection and radiation heat transfer characteristics in an iso-flux upward-facing cylindrical cavity were studied by three-dimensional numerical simulation.The impacts of cavity tilt angle,wind incident angle and wind speed on convection and radiation heat transfer Nusselt number Nuc and Nur were analyzed,and the possible explanations for their impacts were presented.Results show that due to the disturbance of wind,the influence of cavity tilt angle becomes more complicated and is related to wind incident angle and wind speed.The variation of Nuc or Nur with wind incident angle is different for different cavity tilt angles.Despite of the changes of cavity tilt angle or wind incident angle,the Nuc increases with the wind speed while the Nur presents a declination with the increasing of wind speed.Hence,compared with cavity tilt angle and wind incident angle,wind speed may be the dominant factor affecting or controlling the convective and radiation heat transfer of cavity.     

担当

<正>6月30日,当中国政府将《强化应对气候变化行动——中国国家自主贡献》提交给联合国气候变化框架公约秘书处后,全世界都为中国的决定而侧目。中国设定了一个宏大的减排目标,振奋了各国应对气候变暖的神经。潘基文在声明中称赞中国提出的方案为在巴黎气候变化大会上增加动力、增强互信起到了积极推动作用;联合国秘书长副发言人哈克表示,中国提交自主贡献文件,为巴黎气候大会达成新的气候变化协议注入了动力,     

太阳能干燥系列讲座(1)太阳能干燥——太阳能热利用中不可忽视的领域

一物料干燥的能耗与环境污染 干燥作业涉及国民经济的广泛领域,是许多行业不可缺少的工序.在粮食、食品、果品、药材、木材、皮革、橡胶和陶瓷等许多产品的加工处理过程中,干燥作业对产品的质量和成本影响很大.     

户用小型风力发电系统现状与发展(上)

<中华人民共和国可再生能源法>已于2005年2月28日在全国人大第11届第14次会议上通过,并将于2006年1月1日起施行,该法的颁布和实施,给小型风力发电行业的发展带来希望和光明,也必将大大促进农村能源的发展,户用风力发电产业也将会更上一层楼,前景看好.     

两种产自云南的生物质燃烧性质研究

用热天平对产自我国云南省的两种生物质－烟梗和木屑的热解和燃烧性质进行了研究,比较了燃烧特点,利用ＩＣＰ分析了灰成分,并用热台显微镜测定了灰熔点,讨论了它们的灰污特性。结果表明：木屑的着火性能比烟梗的差一些,但木屑的燃烧速度比烟梗的高,燃尽性能比烟梗的好;两者均具有很强的灰污趋向,但烟梗由于有较高的灰含量和钾含量,其实际灰污性比木屑的强;两者形成灰污的机理也不一样。     

In situ photodeposition of metalloid Ni2P co-catalyst on Mn0.5Cd0.5S for enhanced photocatalytic H2 evolution with visible light

Developing a suitable and low-cost co-catalyst is highly desired for promoting photocatalytic water splitting of H₂ production. Herein, we adopted a simple in situ photodeposition strategy by coupling Mn_0.5Cd_0.5S with non-noble co-catalyst Ni₂P to construct Ni₂P/Mn_0.5Cd_0.5S composites and achieved obviously improved H₂ amount (31.83 mmol/h/g) in visible-light region, which is nearly 2.8 times than that of pure Mn_0.5Cd_0.5S. Such photocatalytic performance is in a relatively superior position among Mn_xCd_1?xS-based photocatalysts. The apparent quantum efficiency of Ni₂P/Mn_0.5Cd_0.5S-7 composites reaches 32% at 420 nm. Through optical and photoelectrochemical measurements, a possible mechanism was proposed, it was found that the interface between metalloid Ni₂P and Mn_0.5Cd_0.5S contacts closely, which facilitates transfer and separation of charge carriers, thus promotes the reduction of H⁺ to H₂. This study provides a new design of cut-price, high-efficiency photocatalyst for H₂ evolution.     

LPG与汽油燃料微粒排放的时效特性研究

介绍了应用液化石油气(LPG)和汽油燃料时，微粒排放时效特性的对比研究。试验在一台四冲程、水冷125mL、点燃式单缸电喷发动机上进行。试验结果表明：对于两种燃料，随着沉降时间的增加，微粒排放的粒数不但大幅度下降，其粒度分布规律也发生了明显的变化；LPG和汽油燃料排出的小粒径部分微粒在空气中存在时间短，在排出后15min左右即可大部分挥发或凝聚形成大粒径粒子，而挥发消失的颗粒物比率LPG大于汽油；80％以上的大粒径部分(≥O．237um)粒子是在沉降过程中形成的；在测试条件下，汽油燃料微粒排放的大粒径部分粒子比LPG燃料容易沉降或挥发，随着沉降时间的延长，LPG与汽油微粒排放物的粒度分布特性趋于同一水平。     

Thermal and emission characteristics in a tangentially fired boiler model furnace

Tangentially fired furnaces are vortex‐combustion units and are intended for use as low NO formation furnaces. NO characteristics inside these furnaces depend on many parameters. The present study investigates numerically the problem of pollution in a real furnace of a 1699 MW tangentially fired boiler having 32 burners. NO formation contour maps in a tangentially fired furnace are presented. The study covered different combustion air temperature values, different fuel–air ratios and different cases of tripped burners. Available experimental measurements were used for validating the calculation procedure. The details of the temperature and NO fields were obtained from the solution of the conservation equations of mass, momentum and energy and transport equations for scalar variables in addition to the equations of the turbulence model. The equations governing the NO formation were solved to calculate the NO distribution. The simulation provided more insight on the correlation between the total NO concentration and the maximum furnace temperature and furnace average temperature. The results have shown that the furnace average temperature and NO concentration decrease as the excess air factor increases for a given air mass flow rate. As the combustion air temperature increases, furnace temperature increases and the thermal NO concentration increases sharply. The results show that the temperature distributions are significantly distorted by tripping any of the burners. The results show that tripping one or two burners either adjacent or opposite or tripping four results in regions of high temperature gases close to the walls. Heat absorptions in super‐heater and economizer are greatly influenced by combustion air temperature and excess air factor and are slightly influenced by burner tripping. Copyright © 2009 John Wiley & Sons, Ltd.     

Study on the heat transfer and flow characteristics in a spiral-coil tube

In the present study, numerical and experimental results of the heat transfer and flow characteristics of the horizontal spiral-coil tube are investigated. The spiral-coil tube is fabricated by bending a 8.00 mm diameter straight copper tube into a spiral-coil of five turns. The innermost and outermost diameters of the spiral-coil are 270.00 and 406.00 mm, respectively. Hot and cold water are used as working fluids. The k-ε standard two-equation turbulence model is applied to simulate the turbulent flow and heat transfer characteristics. The main governing equations are solved by a finite volume method with an unstructured nonuniform grid system. Experiments are performed to obtain the heat transfer and flow characteristics for verifying the numerical results. Reasonable agreement is obtained from the comparison between the results from the experiment and those obtained from the model. In addition, the Nusselt number and pressure drop per unit length obtained from the spiral-coil tube are 1.49 and 1.50 times higher than those from the straight tube, respectively.     

EGR对可变压缩比SI发动机动力性和经济性的影响

基于一台可变压缩比SI单缸发动机,在不同EGR率(0~20%)、不同压缩比(8∶1~11∶1)条件下,对发动机动力性和经济性进行对比分析研究。结果表明:发动机的有效热效率、IMEP和功率在EGR率较小时变化均不明显,但随着EGR率继续增大,三者都迅速下降。而增大压缩比会使有效热效率、IMEP和功率在不同程度上都有所升高。同时,在全负荷或定负荷工况下,有效燃油消耗率总体上随EGR率的增大而升高,但在EGR率较小时变化比较平缓。随着压缩比增大发动机有效热效率越高,燃油利用率越高,有效燃油消耗率逐渐降低。     

辽宁省场次暴雨时空分布特征研究

基于辽宁省基础水文数据库,选取资料完整可靠的481处雨量站作为代表站,筛选出1965～2014年间最大点降水量超过200mm的超标准暴雨124场,采用线性倾向估计、M-K检验、小波分析、克里金插值等技术,系统分析了辽宁省场次暴雨时空分布特征。结果表明,辽宁省超标准暴雨年发生次数在0～6次/年之间,年际变化基本持平,并呈现出3～5、13～15年2个主要周期;年内尺度上,超标准暴雨集中发生于7～8月,且主峰降水多集中于24h之内;空间分布上,暴雨中心多位于东南部地区,出现频次由东南部向西北部递减。暴雨中心位于辽西地区的场次暴雨多发生于7月;暴雨中心位于辽东地区的场次暴雨在7、8月均有发生,且位于东南部地区的暴雨多发生于8月。     

锅炉单相受热面动_静态特性通用计算方法

在流体微远追踪计算方法的基础上,提出了锅炉单相受热面热力过程动,静态特性的通用计算方法。利用该算法模型既可以进行锅炉单相受热面的动态过程分析,又能够完成锅炉单相受热面热力特性的静态校核计算,并能十分方便地确定出锅炉单相受热面热力参数的动,静态分布情况。     

An experimental study on performance and emission characteristics of a hydrogen fuelled spark ignition engine

In the present paper, the performance and emission characteristics of a conventional four cylinder spark ignition (SI) engine operated on hydrogen and gasoline are investigated experimentally. The compressed hydrogen at 20  MPa has been introduced to the engine adopted to operate on gaseous hydrogen by external mixing. Two regulators have been used to drop the pressure first to 300 kPa, then to atmospheric pressure. The variations of torque, power, brake thermal efficiency, brake mean effective pressure, exhaust gas temperature, and emissions of _NOx${\mathrm{NO}}_x$, CO, _CO2${\mathrm{CO}}_2$, HC, and _O2${\mathrm{O}}_2$ versus engine speed are compared for a carbureted SI engine operating on gasoline and hydrogen. Energy analysis also has studied for comparison purpose. The test results have been demonstrated that power loss occurs at low speed hydrogen operation whereas high speed characteristics compete well with gasoline operation. Fast burning characteristics of hydrogen have permitted high speed engine operation. Less heat loss has occurred for hydrogen than gasoline. _NOx${\mathrm{NO}}_x$ emission of hydrogen fuelled engine is about 10 times lower than gasoline fuelled engine. Finally, both first and second law efficiencies have improved with hydrogen fuelled engine compared to gasoline engine. It has been proved that hydrogen is a very good candidate as an engine fuel. The obtained data are also very useful for operational changes needed to optimize the hydrogen fueled SI engine design.     

多孔泡沫金属散热模型数值模拟与分析

多孔泡沫金属在紧凑型换热器领域具有广阔的应用前景。本文对具有随机结构的多孔介质中的流动和传热进行了耦合分析。采用有限元法研究了不同孔隙率(30%、50%、70%和90%)泡沫多孔材料的传热特性和阻力特性。利用 作为性能评价指标,即h越大,Δp越小,换热性能越好。通过改变孔隙度和入口流速从而分析整体的换热性能。结果表明,对于换热特性,泡沫金属的对流换热在高度方向上存在明显的温度梯度,边界层沿流动方向可以很好地发展,在高流速下具有更好地换热能力。随着孔隙率的增大,流体扰动变少从而局部速度将会减小,因此换热量也会降低。对于阻力特性,随着孔隙率的减小,内部压力显著增大,压力损失也显著变大。孔隙率为70%时,多孔泡沫金属具有更高的均匀性,同时通过实验验证了模型具有一定的有效性。