汽车发动机尾气余热温差发电装置结构研究

半导体温差发电技术在低品位余热回收技术领域具有重要的应用价值。汽车尾气温度高,带走的热量约占发动机总量的40%,温差发电技术能直接将废热能量转化为电能回收利用。介绍温差发电装置的设计原理,结构参数对性能影响以及装置输出性能参数,并结合试验对温差发电装置的传热性能和电功率输出性能进行分析以及提出有效的改进方案。     

落丸清灰技术协助翅片管在高粘结性烟气余热回收中的应用

介绍了细粒径落丸清灰技术在翅片管余热锅炉清灰上的应用状况和技术特点,建立了冷态和热态清灰试验系统,在矿热炉余热发电系统的试用表明,对于烟尘粘度大的余热回收及发电系统,细粒径落丸可以有效解决该类系统的余热锅炉清灰问题,提高余热回收及发电水平。     

双热源集成发电系统研究

阐述了烧结工序中烧结机烟气和冷却机废气两种余热分布规律及协同回收利用原则,对立式逆流冷却机、热废气-烟气双热源余热锅炉装置、三进口余热锅炉装置及双余热源集成发电系统进行了研究,并以宝钢2号烧结余热回收系统余热源参数为基础,在烧结机烟气和冷却机废气携带热量不变的工况下,对研发的集成发电系统选定两种方案与原余热回收方案进行热经济性计算与对比分析.结果表明：双源集成发电系统两种方案的余热锅炉效率分别达到了73.4%和69.0%,发电净功率分别达到了16.40 MW和15.40 MW,研究结果可为中低品位余热高效回收装置的研发提供科学依据和技术支撑.     

双热源集成发电系统研究

阐述了烧结工序中烧结机烟气和冷却机废气两种余热分布规律及协同回收利用原则,对立式逆流冷却机、热废气-烟气双热源余热锅炉装置、三进口余热锅炉装置及双余热源集成发电系统进行了研究,并以宝钢2号烧结余热回收系统余热源参数为基础,在烧结机烟气和冷却机废气携带热量不变的工况下,对研发的集成发电系统选定两种方案与原余热回收方案进行...     

基于TED原理的燃气灶发电模型及数值模拟

为了提高资源的有效利用率,对燃气灶等设备进行废热回收,提出一种温差发电模型。运用FLUENT软件对该发电装置的温度场、流场进行了三维仿真计算。研究热端设置成格栅结构、热端与水平面的倾斜角大小对余热回收效率的影响。结果表明:将热端设计成格栅结构可以有效提高其辐射温度,改变热端与水平面的倾斜角可以将冷热端温差最高提升57%,进而可以提高温差发电装置的热效率。     

低温蒸汽_太阳能双热源ORC发电系统热力性能分析

为充分回收矿藏热采过程尾端低温蒸汽余热,提出一种通过利用太阳能热量补充预热器中热源显热以缩小换热温差的新型低温蒸汽-太阳能双热源ORC发电系统。根据热力学第一、第二定律,建立其热力学模型,编制计算程序并进行了热力性能分析及比较。计算结果表明:采用热源补助可有效减小换热温差,进而显著提升系统热力性能。当采用R245fa作为循环工质时,与基本的ORC系统相比,选择冷端温差较小的预热器可使双热源系统火用效率显著增加;在预热器冷端温差为30 K、两系统分别采用5种不同循环工质时,双热源ORC系统的热力性能均高于基本ORC系统,且以R236fa为工质的双热源ORC系统热力性能最佳。     

热泵回收电厂循环水余热模型的热经济性分析

在火电机组中,汽轮机乏汽的热量被排放到环境中,致使机组冷源损失较大,机组发电热效率难以提升,并且会造成环境的热污染,为了回收大量循环水余热,以NZK660-24.2/566/566为例,利用热泵技术,拟将回收的循环水余热利用到本机组的给水系统之中,取代7号加热器的抽汽.建立余热回收的物理模型和数学模型,对机组进行热经济性分析与计算,并和原来机组进行对比,结果表明该模型提高了机组的热经济性.作为火电机组冷源优化方式的一种新的尝试,为火电机组余热回收的研究提供了参考.     

夏热冬冷地区居住小区燃气分布式能源系统应用分析

<正>燃气分布式能源系统以天然气为主要燃料,在用户侧安装发电机组,利用燃料高品位的能量发电,产生的电力与市电共同满足用户电力需求,同时通过余热回收利用设备(如余热蒸汽锅炉、溴化锂吸收式冷热水机组、换热器等)回收发电所产生的余热热量,向用户供冷或供热,满足用户的冷负荷或热负荷需求。1燃气分布式能源系统优势(1)供电可靠性高分布式能源系统以燃烧天然气为用户提供电力,为用户增加了一路供应电源,大大减少了对电网的依赖     

大中型沼气工程增温及控制系统运行管理策略

针对北方地区大中型养殖场沼气工程,制定一套发酵罐体增温及控制系统的运行管理策略,它分为供暖期与非供暖期两种模式。阐述两种系统的工作原理,对系统的热负荷、发电余热回收、沼气锅炉采暖及锅炉回水余热回收进行理论计算,并进行设备选型。计算可得:发酵系统平均每日热负荷为3.26 GJ,余热锅炉每日可提供的发电尾气余热回收量为3.64 GJ,发电量为1300 k Wh/d;通过板式换热器与沼气锅炉回水换热,每日集热量为4.41 GJ,可满足维持发酵罐体正常发酵温度的要求,从而保证厌氧发酵系统的稳定运行。     

基于菲涅尔透镜聚光的遮阳伞温差发电系统

为了使太阳能可以得到更加充分的利用,设计了一种应用在大型遮阳伞上的半导体温差发电系统。本设计运用半导体材料的塞贝克效应,利用半导体温差发电片进行发电,通过菲涅尔透镜的聚光作用来为半导体温差发电片的热端加热,采用水冷的方式为其冷端散热,并用蓄电池储存半导体温差发电片所产生的电能。通过实验,得到了菲涅尔透镜与温差发电片的相对布置距离以及冷却水流速对温差发电片输出功率的影响。     

Aerodynamic performance effects of leading-edge geometry in gas-turbine blades

The purpose of this paper is to illustrate the advantages of the direct surface-curvature distribution blade-design method, originally proposed by Korakianitis, for the leading-edge design of turbine blades, and by extension for other types of airfoil shapes. The leading edge shape is critical in the blade design process, and it is quite difficult to completely control with inverse, semi-inverse or other direct-design methods. The blade-design method is briefly reviewed, and then the effort is concentrated on smoothly blending the leading edge shape (circle or ellipse, etc.) with the main part of the blade surface, in a manner that avoids leading-edge flow-disturbance and flow-separation regions. Specifically in the leading edge region we return to the second-order (parabolic) construction line coupled with a revised smoothing equation between the leading-edge shape and the main part of the blade. The Hodson–Dominy blade has been used as an example to show the ability of this blade-design method to remove leading-edge separation bubbles in gas turbine blades and other airfoil shapes that have very sharp changes in curvature near the leading edge. An additional gas turbine blade example has been used to illustrate the ability of this method to design leading edge shapes that avoid leading-edge separation bubbles at off-design conditions. This gas turbine blade example has inlet flow angle 0°, outlet flow angle −64.3°, and tangential lift coefficient 1.045, in a region of parameters where the leading edge shape is critical for the overall blade performance. Computed results at incidences of −10°,   −5°,   +5°,   +10° are used to illustrate the complete removal of leading edge flow-disturbance regions, thus minimizing the possibility of leading-edge separation bubbles, while concurrently minimizing the stagnation pressure drop from inlet to outlet. These results using two difficult example cases of leading edge geometries illustrate the superiority and utility of this blade-design method when compared with other direct or inverse blade-design methods.     

Hydrogen production by steam-gasification of carbonaceous materials using concentrated solar energy – V. Reactor modeling,optimization, and scale-up

A chemical reactor for the steam-gasification of carbonaceous particles (e.g. coal, coke) is considered for using concentrated solar radiation as the energy source of high-temperature process heat. A two-phase reactor model that couples radiative, convective, and conductive heat transfer to the chemical kinetics is applied to optimize the reactor geometrical configuration and operational parameters (feedstock's initial particle size, feeding rates, and solar power input) for maximum reaction extent and solar-to-chemical energy conversion efficiency of a 5 kW prototype reactor and its scale-up to 300 kW. For the 300 kW reactor, complete reaction extent is predicted for an initial feedstock particle size up to 35 μm at residence times of less than 10 s and peak temperatures of 1818 K, yielding high-quality syngas with a calorific content that has been solar-upgraded by 19% over that of the petcoke gasified.     

汽轮机数字电液调节系统挂闸异常的技术完善

分析了200MW汽轮机数字电液调节系统在运行中存在的挂闸异常问题,采取了相应的技术处理措施,且运行实践效果良好。     

新型高压共轨ECU升压模块的数字化开发与优化

为了提高喷油器电磁阀的响应速率,提出了一种基于CPLD(复杂可编程逻辑器件)应用于高压共轨ECU的数字升压模块。鉴于该升压电路结构参数多,其升压电压的恢复响应要求高等特征,基于Pspice建立了升压电路的仿真模型,研究了不同电路参数下升压模块的输出特性,全面优化了该升压模块的性能。结果显示,该升压模块的最大转换效率可以达90%以上。在柴油发动机上对ECU的试验表明,升压电压最大波动不超过10%,其恢复时间仅为1.3ms,功率管最大温升仅为41℃,满足整机运行范围内ECU的需求。     

Trace metal chemistry and silicification of microorganisms in geothermal sinter, Taupo Volcanic Zone, New Zealand

As part of a pilot study investigating the role of microorganisms in the immobilisation of As, Sb, B, Tl and Hg, the inorganic geochemistry of seven different active sinter deposits and their contact fluids were characterised. A comprehensive series of sequential extractions for a suite of trace elements was carried out on siliceous sinter and a mixed silica-carbonate sinter. The extractions showed whether metals were loosely exchangeable or bound to carbonate, oxide, organic or crystalline fractions. Hyperthermophilic microbial communities associated with sinters deposited from high temperature (92–94°C) fluids at a variety of geothermal sources were investigated using SEM. The rapidity and style of silicification of the hyperthermophiles can be correlated with the dissolved silica content of the fluid. Although high concentrations of Hg and Tl were found associated with the organic fraction of the sinters, there was no evidence to suggest that any of the heavy metals were associated preferentially with the hyperthermophiles at the high temperature (92–94°C) ends of the terrestrial thermal spring ecosystems studied.     

Wind power for pumping: The development of the ITP windpump

Water pumping has been one of the main applications for wind power in the past and despite the spread of mains-electric pumps, more than a million windpumps remain in regular use. This paper reviews the general technical and economic requirements for pumping water using wind energy and by way of example gives an overview of the development of the new ITP wind-pump. It then considers the future prospects for this kind of technology.     

Methods of creating solar-reflective nonwhite surfaces and their application to residential roofing materials

We describe methods for creating solar-reflective nonwhite surfaces and their application to a wide variety of residential roofing materials, including metal, clay tile, concrete tile, wood, and asphalt shingle. Reflectance in the near-infrared (NIR) spectrum (0.7–2.5 μm) is maximized by coloring a topcoat with pigments that weakly absorb and (optionally) strongly backscatter NIR radiation, and by adding an NIR-reflective basecoat (e.g., one colored with titanium dioxide rutile white) if both the topcoat and the substrate weakly reflect NIR radiation. Coated steel and glazed clay-tile roofing products achieved NIR reflectances of up to 0.50 and 0.75, respectively, using only cool topcoats. Gray-cement concrete tiles achieved NIR reflectances as high as 0.60 with coatings colored by NIR-scattering pigments. Such tiles could attain NIR reflectances of up to 0.85 by overlaying a white basecoat with a topcoat colored by NIR-transparent organic pigments. Granule-surfaced asphalt shingles achieved NIR reflectances as high as 0.45 when the granules were covered with a white basecoat and a cool color topcoat.     

Thermal decay of an initially hot isothermal water body with application to thermal energy storage

The thermal decay of an initially hot isothermal water body contained in a tank was studied. Analytical solutions (including a group-theoretic solution) were obtained for the one-dimensional heat conduction equation with heat loss from the sides of the tank. The convective heat transfer coefficient was assumed not to be constant over the surface of the tank but to vary with space and time. A very good agreement was obtained between the group-theoretic solution and a numerical solution using the Crank-Nicholson finite difference scheme. The analytical results are discussed in terms of the underlying physical mechanisms.     

Ash-forming elements in four Scandinavian wood species. Part 1: Summer harvest

Woody biomass in Finland and Sweden comprises mainly four wood species: spruce, pine, birch and aspen. To study the ash, which may cause problems for the combustion device, one tree of each species were cut down and prepared for comparisons with fuel samples. Well-defined samples of wood, bark and foliage were analyzed on 11 ash-forming elements: Si, Al, Fe, Ca, Mg, Mn, Na, K, P, S and Cl. The ash content in the wood tissues (0.2–0.7%) was low compared to the ash content in the bark tissues (1.9–6.4%) and the foliage (2.4–7.7%). The woods’ content of ash-forming elements was consequently low; the highest contents were of Ca (410–1340 ppm) and K (200–1310), followed by Mg (70–290), Mn (15–240) and P (0–350). Present in the wood was also Si (50–190), S (50–200) and Cl (30–110). The bark tissues showed much higher element contents; Ca (4800–19,100 ppm) and K (1600–6400) were the dominating elements, followed by Mg (210–2400), P (210–1200), Mn (110–1100) and S (310–750), but the Cl contents (40–330) were only moderately higher in the bark than in the wood. The young foliage (shoots and deciduous leaves) had the highest K (7100–25,000 ppm), P (1600–5300) and S (1100–2600) contents of all tissues, while the shoots of spruce had the highest Cl contents (820–1360) and its needles the highest Si content (5000–11,300). This paper presented a new approach in fuel characterization: the method excludes the presence of impurities, and focus on different categories of plant tissues. This made it possible to discuss the contents of ash element in a wide spectrum of fuel-types, which are of large importance for the energy production in Finland and Sweden.     

秸秆燃烧中温度对钾转化与释放的影响

通过对稻秆原料进行常规特性分析和EDX元素含量分析,发现钾在稻秆无机元素中占有重要地位。参考原料化学分馏法和土壤中钾的分类与测试方法,给出了对生物质原料及其燃烧产物中钾的定性与定量简易方法。通过程序控温型固定床对稻秆先进行缓慢氧化,然后以100℃为间隔从400～900℃进行成灰,并分别测试其成灰率、有效钾和全钾的份额。结合稻秆原料及其灰中钾的份额分析,进行了稻秆灰中有效钾转化与释放的计算,发现有效钾在700～800℃之间有快速的释放和形态转变。稻秆灰的XRD分析结果表明秸秆灰中钾主要以KCl、K_2SO_4形式存在,得到了钾以盐的形式进行转化与释放的机理。该文中燃烧温度对钾转化与释放的影响规律对设计秸秆电厂时的炉型选择和燃烧参数确定有一定参考价值。