基于平板热管的太阳能-空气能双源集热蒸发器性能实验研究

设计一种基于平板热管的太阳能-空气能双源集热蒸发器及由其组成的新型直膨式热泵系统,并对其进行实验研究与分析。实验测试平板热管在制冷剂低温取热条件下的均温性与导热性能,热泵运行工况下集热蒸发器表面温度分布、光电光热性能,以及在不同天气条件不同运行模式下热泵系统性能。结果表明,平板热管在低温取热条件下当量导热系数可达6.8×10⁵W/(m·℃),集热蒸发器运行时纵向最大温差为3.9℃;在夏季晴朗天气条件下运行太阳能模式制热水时热泵平均COP为3.62;在低辐照阴天下运行太阳能-空气能双源模式与太阳能模式相比,单位面积集热功率提高18.8%,系统平均COP提高5.7%;在无辐照的夜晚,运行空气源模式系统COP为2.54。     

日间供暖太阳能热泵系统负荷分析及面积优化

以青岛市某公司办公楼太阳能热泵系统为研究对象,通过TRNBuild建立建筑模型,仿真分析同一建筑全天供暖与日间供暖热负荷分布特点,针对建筑日间供暖需求建立太阳能-空气源热泵仿真供热系统,利用TRNSYS软件进行供热季仿真模拟,计算日间供暖集热器最佳设计面积。仿真结果表明：相较于全天供暖,建筑日间供暖热负荷波动更为剧烈,最大峰值约为全天供暖的2倍,针对日间供暖设计的太阳能热泵系统在集热器面积为417 m²时运行经济性最佳,系统COP可达4.1,对应太阳能贡献率为24.7%,供暖季相较于传统空气源热泵可节约电能9 091 kW·h。     

太阳能与空气源热泵联合供暖系统容量匹配及运行优化

针对川西藏区民居使用太阳能与空气源热泵联合供暖问题进行系统容量匹配及运行优化研究。建立太阳能与空气源热泵并联供暖系统的容量匹配及运行优化模型,以系统生命周期成本最小为优化目标,以集热器面积、热泵容量、水箱容积、热泵启停温度、热泵启停温差为优化变量,采用遗传算法进行同步优化计算。以甘孜地区为计算案例进行优化计算,结果表明:单一运行优化节能效果显著,与设计方法相比,运行费可节省19.0%,系统COP提高24.3%,热泵平均COP提高10.7%;在系统20 a寿命周期内,同步优化方法下总投资最低,与设计方法、单一运行优化和单一容量匹配相比,其总投资分别降低19.1%、11.4%和15.6%。甘孜地区并联供暖系统应以热泵为主,推荐太阳能保证率为16%,给出了优化匹配容量及运行控制策略。     

相变储能太阳能热泵系统的试验研究

文章建立了相变储能太阳能热泵系统试验平台,介绍了系统的运行方式以及各个部分的运行原理,选取典型日进行试验,并对试验数据进行分析。分析结果表明:相变储能太阳能热泵系统能够满足北方农村的供暖需求,可以保证白天室内的温度达到22℃,COP的最大值为6.3;太阳能热泵系统停止工作后,相变储能箱可以保证室内温度达到供暖的需求温度7 h,起到了"削峰填谷"的作用,运行费用显著降低;相变储能太阳能热泵系统解决了单纯电加热供暖方式费用高、能耗高的问题,具有显著的节能性。     

R290直膨式太阳能热泵供暖系统实验研究

为分析直膨式太阳能热泵耦合地板辐射供暖系统在北方寒冷地区的实际运行特性,设计并搭建以丙烷(R290)为工质的直膨式太阳能热泵供暖实验平台,分析冬季不同运行工况下环境参数对系统热力性能的影响。实验结果表明：系统可实现室内供暖的稳定性,实验测试期间平均室温保持在16.1～20.8℃之间,热泵系统性能系数(COP)保持在2.57～4.30之间,供暖系统COP保持在2.24～3.98之间。太阳辐照度每增加50 W/m²,热泵系统COP提升4.9%;环境温度每升高1℃,热泵系统COP提升2.4%。太阳辐照度对热泵系统的电子膨胀阀开度和工质质量流量影响较为显著。当终止水温从45℃提升至55℃时,热泵系统COP降低12.2%;而在终止水温为50℃时,供暖系统COP达到最大值3.37。     

PCM空气式太阳能干燥在茶叶加工中的应用

介绍了云南普洱市的某茶业公司PCM空气式太阳能一热泵联合干燥房建设及应用实例。普洱茶传统加工工艺采用燃煤蒸汽锅炉进行茶饼烘干处理,现进行技术改造,采用节能环保的PCM空气式太阳能热泵干燥系统代替现有的燃煤锅炉干燥系统。通过PCM空气式太阳能集热系统,将太阳能转换热能。以空气为换热介质与空气式太阳能集热器进行换热,通过循环风机直接将热风通入到烘房内提供物料干燥热量需求;当太阳能不足时,启动空气源热泵系统。对该工程的设计方案并及干燥系统工作原理进行了详细介绍,从干燥系统运行过程中采集数据进行分析计算,计算结果表明本干燥系统节能效果明显。这些数据对目前高效利用太阳能进行商业干燥设计参数的选取,以及太阳能干燥系统的优化设计具有重要借鉴意义。     

寒冷地区户用大平板太阳能集热器-空气源热泵系统性能研究

针对太阳能难以单独稳定供暖和空气源热泵供暖成本高的问题，提出空气源热泵辅助太阳能稳定供暖构想，在甘肃省兰州市七里河区魏岭乡绿化村研发搭建大平板太阳能集热器-空气源热泵系统，对比研究晴天、多云和阴天3种典型工况下大平板太阳能集热器的集热效率、太阳能热泵和空气源热泵COP、太阳能保证率、系统总供热量和系统能效比等性能参数。结果表明：晴天、多云和阴天系统集热效率分别为44.9%、38.7%和20.6%,3种工况下太阳能热泵COP均为4.0，空气源热泵COP分别为3.5、3.3和3.1，太阳能保证率分别为38.1%、32.3%和12.9%，系统全天供热量分别为142.52、135.22和120.96 kWh，系统能效比分别为3.5、3.4和2.7。研究结果证明大平板太阳能集热器-空气源热泵系统用于寒冷地区单体建筑供暖的可行性，可为寒冷地区农村单体建筑的供暖提供一种新途径。     

太阳能热泵系统配置形式及其研究进展

采用不同用途及配置形式相结合的分类方法对太阳能热泵系统进行分类，指出不同形式太阳能热泵系统的特点、当前研究现状及未来发展趋势，分析环境及运行参数对系统热力性能的影响。通过文献综述发现，在一定运行工况下，直膨式太阳能热泵系统性能系数（COP）值可达9.40以上，非直膨式太阳能热泵系统COP值可达8.80以上。提出太阳能热泵系统的应用与研究应从能耗与效率、经济性、可靠性、运行与操控等方面着手，朝更加高效经济、节能可靠的方向发展。     

基于R1234yf和R134a制冷剂的太阳能-空气源复合热泵性能对比

随着化石能源的过度消耗与环境问题日益加剧,发展清洁可再生能源势在必行。针对太阳能-空气源复合热泵系统性能进行分析,结果表明:模式二时,太阳能热泵系统与空气源热泵系统的COP分别为6.55和4.81;平板式太阳能集热器的热效率高达67.86%;在相同制热功率条件下,与模式一相比,模式二时空气源热泵耗功平均降低87.81%,太阳能热泵耗功平均降低16.17%;采用R1234yf的系统耗功比R134a系统高2%~3.17%,但R1234yf的温室效应值极低。     

复合热源太阳能热泵供热系统及其性能模拟

提出了一种复合热源太阳能热泵供热系统,通过阀门切换,可根据不同的天气状况改变运行模式,以空气和太阳辐射作为热源制取供暖用水。针对所设计的10kW供热系统,建立了系统的数学模型,对热泵串联集热器(SC+HP)及集热器串联热泵(H+SC)两种运行模式下的循环性能进行了计算机模拟分析,并计算了系统的全年运行状况。从模拟结果可以看出,在模拟进水温度区间内,HP+SC模式下热泵COP较高,最高比SC+HP模式高2.58%;而SC+HP模式集热器热性能较好,总热效率更高,最高比HP+SC模式高2.62%。     

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。