共查询到19条相似文献,搜索用时 171 毫秒
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《低温与超导》2016,(2)
设计了涡流管实验样机,在不同进口压力和冷流比工况下,实验测量了三种冷端孔径的涡流管性能,并分析了冷端孔径、喷嘴环端面间隙及进口压力对涡流管性能的影响。实验结果表明,冷端孔径为5mm的涡流管降温及制冷性能最佳,最佳冷端孔径与涡流管径之比为0.5。在进口压力为0.4MPa工况下,其冷端最大温降分别比冷端孔径为4mm和6mm的涡流管大6.1℃和2.9℃,最大制冷量分别大30.2%和5.4%;在所有进口压力工况下,对应于最大冷端温降的最佳冷流比约为0.5,而对应于最大制冷量的最佳冷流比约为0.65。在进口压力为0.3~0.5MPa范围内,涡流管冷端温降和制冷量均随着进口压力的升高而增大,且进口压力越高,冷端温降的增长速度越慢;制冷性能系数COP随着进口压力的升高而降低,而等熵温度效率则几乎不随进口压力改变而变化,仅是冷流比的函数。同时,实验发现,喷嘴环端面间隙对涡流管能量分离效应影响很大,设计制造过程中必须消除其影响。 相似文献
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热泵对于缓解我国北方冬季所面临的供暖压力,具有十分积极的作用。本文主要针对一种新型的双效自由活塞斯特林变温热泵技术展开研究。主要采用SAGE程序对整机系统进行了数值计算,探究变温泵热对于系统加热量、泵热量、制热系数、整机(火用)效率以及各关键部件(火用)损失等热力学参数的影响。计算结果表明,采用变温热泵模式时,由于斯特林热泵侧温差减小,其泵热量增加,因此系统总的泵热量以及制热系数增大,但对应的(火用)效率降低。因此,可以在满足热量匹配的情况下,适当降低热泵侧室温换热器温度对热负载流体进行逐级加热,从而提高双效自由活塞斯特林热泵系统的工作效率。 相似文献
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The dynamics of a vortex tube in a compressible medium with the Rayleigh energy release mechanism has been considered theoretically. The analytic theory of this phenomenon is constructed and various approximations have been considered. The range of applicability conditions for the vortex formation theory has been extended substantially. It has been shown based on the model of a plasma as a Rayleigh medium that, for a certain relative orientation of the vortex axis and the electric field vector at an air pressure of tens of Torr, a vortex tube in the glow discharge plasma is destroyed over time intervals on the order of hundredths of a second. It has been found that allowance for the compressibility leads to an increase in the rate of vortex destruction. For this medium, the time dependences of the tangential velocity in a vortex tube have been calculated for various initial parameters. The similarity rules for the given phenomena and the universal dependence of the vortex tube dynamics have been obtained. 相似文献
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Energy, exergy, and exergoeconomic evaluations of various geothermal configurations are reported. The main operational and economic parameters of the cycles are evaluated and compared. Multi-objective optimization of the cycles is conducted using the artificial bee colony algorithm. A sensitivity assessment is carried out on the effect of production well temperature variation on system performance from energy and economic perspectives. The results show that the flash-binary cycle has the highest thermal and exergy efficiencies, at 15.6% and 64.3%, respectively. The highest generated power cost and pay-back period are attributable to the simple organic Rankine cycle (ORC). Raising the well-temperature can increase the exergy destruction rate in all configurations. However, the electricity cost and pay-back period decrease. Based on the results, in all cases, the exergoenvironmental impact improvement factor decreases, and the temperature rises. The exergy destruction ratio and efficiency of all components for each configuration are calculated and compared. It is found that, at the optimum state, the exergy efficiencies of the simple organic Rankine cycle, single flash, double flash, and flash-binary cycles respectively are 14.7%, 14.4%, 12.6%, and 14.1% higher than their relevant base cases, while the pay-back periods are 10.6%, 1.5% 1.4%, and 0.6% lower than the base cases. 相似文献
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低温太阳热能与化学链燃烧相结合控制CO2分离动力系统 总被引:3,自引:1,他引:2
本文探索并提出控制CO2分离的低温太阳热能与清洁合成燃料甲醇-三氧化二铁化学链燃烧相结合的新颖能源动力系统。基于图象(?)分析方法,明确地指出甲醇化学链燃烧能量释放过程燃烧堋损失减小和低温太阳热能品位提升的机理。从能源有效利用和环境相容出发,研究和揭示化学链燃烧与太阳能有机整合共同减小CO2分离能耗的特性规律。相比不分离常规联合循环,新系统(?)效率提高约6.2个百分点;与分离CO2的联合循环相比,新系统媚效率提高约14.2个百分点。同时,低温太阳热能热转功效率可达到22.5%。 相似文献
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Shuxing Zhang Xiaoshu Ding Helen Shang Yucong Song Yanji Wang 《Entropy (Basel, Switzerland)》2022,24(10)
Dimethyl carbonate is an important green chemical that has been widely used in the chemical industry. In the production of dimethyl carbonate, methanol oxidative carbonylation has been studied, but the conversion ratio of dimethyl carbonate using this method is too low, and the subsequent separation requires a large amount of energy due to methanol and dimethyl carbonate being azeotrope. In this paper, the strategy of “reaction instead of separation” is proposed. Based on this strategy, a novel process is developed to combine the production of DMC with that of dimethoxymethane (DMM) and dimethyl ether (DME). The co-production process was simulated using Aspen Plus software, and the product purity was up to 99.9%. The exergy analysis of the co-production process and the existing process was carried out. The exergy destruction and exergy efficiency were compared with those of the existing production processes. The results show that the exergy destruction of the co-production process is about 276% less than that of the single-production processes, and the exergy efficiencies in the developed co-production process are significantly improved. The utility loads of the co-production process are significantly lower than that of the single-production process. The developed co-production process increases the methanol conversion ratio to 95%, with a reduced energy requirement. It is proved that the developed co-production process can provide an advantageous option over the existing processes with improved energy efficiency and material savings. The strategy of “reaction instead of separation” is feasible. A new strategy is proposed for azeotrope separation. 相似文献
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本文针对传统焦炭生产工艺的不足、并应用联产系统整合思路,研究提出新型焦炭动力联产系统.新系统取消了传统炼焦工艺中直接燃用焦炉煤气为炭化室提供炼焦热量的方式,采用外置煤炭燃烧室提供热量,从而实现用低品质煤炭替代高品质焦炉煤气;节省下来的富氢、高热值的焦炉煤气作为燃料提供给联合循环,实现高效洁净发电;改进炼焦过程烟气废热回收方式,使得排烟损失大大降低.分析结果表明,新系统具有优良的热力性能,相对节能率高达15%左右.对系统关键过程的图像(火用)分析分析表明,燃烧过程和换热过程等变革与改进是系统性能提升的关键所在.本文研究将为冶金生产的可持续发展提供新思路与新系统方案. 相似文献