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一种新型混合吸收式制冷循环的性能分析 总被引:1,自引:0,他引:1
该文提出一种新型吸收式循环,可以较好利用太阳能实现制冷,解决传统吸收式系统在利用太阳能实现制冷时存在的弊端。这种新型混合式吸收式制冷循环在两级吸收式循环的基础上增设了一个附加高压发生器,发现影响系统COP值的因素主要是LiBr溶液浓度与低压发生器中的压力。在溶液浓度与压力的允许范围内时,新型循环的高压发生器再生出LiBr溶液与低压吸收器的吸收后的溶液混合,提高高压吸收器吸收剂浓度从而减小其压力。本文主要分析了混合吸收式制冷循环的各种性能特性,得出影响系统热力系数(COP)可达0.55,驱动热源的可利用温差最高可达35℃。 相似文献
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低温热源驱动的单效/双级(SE/DL)吸收式制冷循环 总被引:10,自引:0,他引:10
文章提出了一种可以充用利用低温热源(水、汽等)驱动而获得较高制冷量的新型吸收式制冷循环(单效/双级循环)。该循环采用加大源温差的思路,具有单效循环和双级循环的优点。文中给出了循环的流程、各设备的有关计算公式和循环的性能指标,并在模拟计算的基础上,对循环性能进行了研究比较。结果表明,本循环适于以低温热水为驱动热源,循环热力系数在0.42-0.62之间,热源出口温度可降到55℃左右,并可在57.5℃左右获得最大制冷量,其值约等于由相同进口温度、相同流量的热水驱动的单效机的4倍。因此,该循环特别适宜于利用低品位废热、地热、冷热电三联供、太阳能制冷等场合,具有很好的经济性和节能效果。 相似文献
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基于南海地区渔业冷库的实际需求,结合海洋温差能综合利用技术,提出一种利用太阳能辅热的吸收式双级引射增压OTEC动力-制冷混合循环。该混合循环以太阳集热器加热的表层温海水作为循环热源,同时以深层冷海水作为循环冷源,可兼顾渔业冷库制冷与发电。建立该动力-制冷混合循环模型,并对该循环进行热力学分析。结果表明:混合循环冷库温度可达到-30℃以下,混合循环有效效率为7.82%;与OTEC制冷动力复合循环相比,采用压缩制冷的混合循环制冷量可增加70.5%,制冷温度降低12℃;提高太阳集热器出口温度有助于提升混合循环热力性能,而过高的发生器压力则会降低混合循环热力性能。 相似文献
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氨水喷射-吸收式制冷循环的研究 总被引:6,自引:0,他引:6
对喷射增压的氨水吸收式制冷循环进行分析和热力计算,分别与一般的氨水吸收式循环相比,前在相同的热源温度下,获取的最低蒸发温度能够降低10℃左右,单级喷射-吸收系统的COP一直保持在O.3左右,双级喷射-吸收系统的COP在O.2左右。虽然在较高的蒸发温度段该制冷循环的性能系数略有降低,但是它能够利用现实中许多低品位的热源获取更低的蒸发温度。 相似文献
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模拟太阳能驱动吸收式装置的试验研究 总被引:3,自引:2,他引:3
报道了溴化锂吸收式制冷和供热两用装置在由模拟太阳能集热器提供的67-75℃热水驱动下,实施制冷循环及Ⅱ型热泵循环的试验研究结果。给出了驱动热水温度为定值及变值时吸收式装置的性能和经济指标随运转参数的变化关系,并分析了经济运行工况、制冷量与供热量间匹配关系及系统的节能效果。 相似文献
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利用氨水吸收式循环将太阳能与地热两个热源结合,提出了一种新颖的制冷与供热系统。由于热源温差的协调配置,该系统具有更高的能量利用特性。还研究了热源温度以及重要内部操作条件对系统制冷、供热效率的影响规律,探讨了该系统的可行性。 相似文献
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低焓能吸收式制冷系统的分析与改进 总被引:1,自引:0,他引:1
本文对简单吸收式制冷循环及三压吸收式制冷循环进行新的分析,并对三压吸收式制冷循环做了改进,从而较大幅度地提高了循环的热力系数,又不过分增加系统的复杂性,本文学分析了可以用于该循环的工质对问题。 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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《热能动力工程》2014,(5)
正1 ABSTRACT To reduce the effect of global warming on our climate,the levels of CO2emissions should be reduced.One way to do this is to increase the efficiency of electricity production from fossil fuels.This will in turn reduce the amount of CO2emissions for a given power output.Using US practice for efficiency calculations,then a move from a typical US plant running at 37%efficiency to a 760℃/38.5 MPa(1 400/5 580 psi)plant running at 48%efficiency would reduce CO2emissions by 170kg/MW.hr or 25%. 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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The physical aspects of the activation energy, in higher and high temperatures, of the metal creep process were examined. The research results of creep-rupture in a uniaxial stress state and the criterion of creep-rupture in biaxial stress states, at two temperatures, are then presented. For these studies creep-rupture, taking case iron as an example the energy and pseudoenergy activation was determined. For complex stress states the criterion of creep-rupture was taken to be Sdobyrev's, i.e. σred = σ1 β + (1 − β)σi, where: σ1-maximal principal stress, σi-stress intensity, β-material constant (at variable temperature β = β(T)). The methods of assessment of the material ageing grade are given in percentages of ageing of new material in the following mechanical properties: 1) creep strength in uniaxial stress state, 2) activation energy in uniaxial stress state, 3) criterion creep strength in complex stress states, 4) activation pseudoenergy in complex stress states. The methods 1) and 3) are the relatively simplest because they result from experimental investigations only at nominal temperature of the structure work, however, for methods 2) and 4) it is necessary to perform the experimental investigations at least at two temperatures. 相似文献
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Jaime Massanet-Nicolau Alan Guwy Richard Dinsdale Giuliano Premier Sandra Esteves 《International Journal of Hydrogen Energy》2010
Hydrogen was produced from primary sewage biosolids via mesophilic anaerobic fermentation in a continuously fed bioreactor. Prior to fermentation the sewage biosolids were heated to 70 °C for 1 h to inactivate methanogens and during fermentation a cellulose degrading enzyme was added to improve substrate availability. Hydraulic retention times (HRT) of 18, 24, 36 and 48 h were evaluated for the duration of hydrogen production. Without sparging a hydraulic retention time of 24 h resulted in the longest period of hydrogen production (3 days), during which a hydrogen yield of 21.9 L H2 kg−1 VS added to the bioreactor was achieved. Methods of preventing the decline of hydrogen production during continuous fermentation were evaluated. Of the techniques evaluated using nitrogen gas to sparge the bioreactor contents proved to be more effective than flushing just the headspace of the bioreactor. Sparging at 0.06 L L min−1 successfully prevented a decline in hydrogen production and resulted in a yield of 27.0 L H2 kg−1 VS added, over a period of greater than 12 days or 12 HRT. The use of sparging also delayed the build up of acetic acid in the bioreactor, suggesting that it serves to inhibit homoacetogenesis and thus maintain hydrogen production. 相似文献