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降膜蒸发多效回热吸收式太阳能海水淡化系统的实验研究 总被引:2,自引:0,他引:2
基于降膜蒸发与降膜凝结机理,设计建造了一台具有四效回热性能的吸收式太阳能海水淡化系统,用电加热水箱模拟太阳能集热系统,对该系统进行了模拟实验。实验中,对系统的瞬态和稳态性能进行了测试,给出了系统在不同运行温度、压力下的产水速率和性能系数。实验结果表明,由于在本系统中采用了横管、竖管降膜蒸发及降膜凝结技术,使其中大部分的蒸汽潜热及部分盐水的显热得到了多次重复利用,并由于吸收工质对最末效蒸汽进行了主动吸收,回收了蒸汽的焓,从而强化了最后一效的蒸发过程,因而系统具有较高的性能系数。在供热水温度为80℃、系统内部压力为15kPa时,四效装置的性能系数可达到3.0左右,体现出吸收式系统的良好优势。对影响产水率的其他因素也作了探索与分析,给出了合理的取值范围。 相似文献
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横管降膜蒸发内回热式太阳能海水淡化装置的实验研究 总被引:5,自引:5,他引:5
设计建造了一台利用太阳能或其它余热驱动的横管降膜蒸发内回热式海水淡化装置,并利用模拟热源对该装置进行了实验研究,由于在系统的蒸发及冷凝过程中,大部分水蒸汽的凝结潜热被重复利用于海水的预热及蒸发过程,因而系统具有较高的产水率,同时,由于在气流的闭式环过程中,蒸发腔中处于负压状态,冷凝腔中处于正压状态,强化了系统的产水性能,使系统的产水效率比传统的盘式太阳能蒸馏器提高了3倍左右,介绍了系统的瞬态特性及运行温度,供海水流率与产水量的相互关系,对影响系统产水率的其它因素进行了讨论。 相似文献
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一种竖管降膜蒸发太阳能海水淡化装置的实验研究 总被引:1,自引:1,他引:1
设计了一种竖管降膜—横管冷凝的太阳能海水淡化装置。以电加热作为供热热源,在不同的运行参数下进行了实验研究,分析了影响装置性能的各种因素。分析表明:在供能相同的情况下,闭式循环的单位能耗产水率比开式循环提高了约1.0~1.5倍;提高循环热水进口温度有利于提高产水率和单位能耗产水率;海水流率有一个理想取值范围。 相似文献
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提出一种新型横管式太阳能苦咸水淡化装置,介绍装置的工作原理,通过建立装置内传热传质关系,得到单效及两效横管式太阳能苦咸水淡化装置的淡水产量预测值。用电加热管代替太阳能集热系统,对单效和两效装置在稳态运行时测点温度变化和产水速率进行测试。结果表明:两个装置稳态运行时,蒸汽主要在套管内上部进行凝结,产水速率均随加热温度的升高而增大,两效淡化装置在加热温度为80℃时的淡水产量为0.728 kg/h,是单效装置的2.1倍,实验测试值与理论计算值随温度变化趋势一致,两效淡化装置性能系数可达1.67。 相似文献
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多效鼓泡蒸发太阳能海水淡化系统的稳态实验研究 总被引:1,自引:0,他引:1
基于鼓泡蒸发和空气载湿气液相平衡机理,设计并实现了一台具有五级四效性能的鼓泡蒸发式太阳能海水淡化系统,对该系统的稳态产水性能进行研究,给出系统在特定的运行温度和压力环境中,不同鼓气量下各效的产水率、耗电当量及经济性能系数。实验结果表明,系统采用多效鼓泡蒸发技术并对各级采取鼓气量的优化组合措施,可提高系统的产水率。当各级载气流量分别为570、570、570、450L/h时的,装置的淡水产率为1.668L/h,GOR值为2.77,折算单位产量能耗4.93kWh/t,该点为装置的经济性能系数最高的工况点。 相似文献
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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. 相似文献
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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. 相似文献
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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. 相似文献
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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. 相似文献
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Methods of creating solar-reflective nonwhite surfaces and their application to residential roofing materials 总被引:4,自引:0,他引:4
Ronnen Levinson Paul Berdahl Hashem Akbari William Miller Ingo Joedicke Joseph Reilly Yoshi Suzuki Michelle Vondran 《Solar Energy Materials & Solar Cells》2007,91(4):304-314
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. 相似文献
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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. 相似文献
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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. 相似文献
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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。 相似文献