共查询到20条相似文献,搜索用时 109 毫秒
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吸附式制冷系统中吸附床材料热容对系统运行COP的影响分析 总被引:2,自引:0,他引:2
1前言在吸附式制冷系统的理论运行研究中,很少考虑吸附床材料的影响。实际上由于吸附式制冷系统的非连续性,吸附床材料的热容对实际系统运行性能的影响是非常大的。这个影响体现在系统不断地加热和冷却过程中所损失的吸附床材料的显热热量,这个热量的大小直接受吸附床本身设计的影响,另外还受到系统运行过程的影响,如:系统运行的解吸温度、回热所进行的程度等。由于该系统中通常所用的吸附剂均属多孔性材料,其特点是热导率小,密度低,要满足一定的制冷功率,所设计的吸附床往往很大,另外为增强吸附床内的热传递,加快吸附床的冷却… 相似文献
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A model for predicting the effective thermal conductivity of nanofluids is proposed. It has been documented that the interfacial layer at the solid (particle)/liquid interface and particle size is one of the major mechanisms for enhancing the thermal conductivity of nanofluids. Comparing with other classical models, the proposed model takes into account some additional effects including volume fraction, thickness, thermal conductivity of the interfacial layer and particle size. The proposed model is found to be better than the existing models since the predicted effective thermal conductivity of different types of nanofluids are closer to the experimental results. 相似文献
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Sulfonated poly(1,4-phenylene sulfide; SPPS) was prepared from poly(1,4- phenylene sulfide) and fuming sulfuric acid by sulfonation
process. Novel hybrid organic/inorganic composite polymer electrolyte membranes based on sulfonated poly(1,4-phenylene sulfide)
membrane with varying concentrations of zeolite were synthesized. Fourier transform infrared spectroscopy implied the presence
of a specific interaction between SPPS and zeolite particles. Upon increasing the zeolite concentration to 10 wt.%, the proton
conductivity of composite membrane reduced from 0.075 to 0.02 S cm−1 at room temperature which may be due to strong interaction between sulfonic group of SPPS and the zeolite particles. The
water uptake of the composite membrane reduced from 255% to 150% with the increase of the zeolite concentration to 10 wt.%.
The thermal stability analysis showed the enhancement of thermal stability of the composite membranes with increasing concentration
of zeolite. 相似文献
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自激振荡流热管脉冲加热强化传热实验研究 总被引:9,自引:2,他引:7
自激振荡流热管也称为脉动热管,是一种新型高效的传热元件。本文提出了采用脉冲加热代替常规连续热源加热强化自激振荡流热管传热的方法,并对其进行了实验研究。实验结果显示,脉冲加热时热管冷、热端壁面温度的振荡频率明显大于连续加热热管的壁面温度振荡频率。在相同的加热功率下,当脉冲宽度在200-1000 ms时,脉冲加热热管的传输热流量与当量导热系数均大于连续加热热管的传输功率和当量导热系数.这表明脉冲加热强化自激振荡流热管传热的方法是可行的. 相似文献
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K. Karuppasamy R. Antony S. Thanikaikarasan S. Balakumar X. Sahaya Shajan 《Ionics》2013,19(5):747-755
A sequence of novel plasticized polymer nanocomposite electrolyte systems based on polyethylene oxide (PEO) as polymer host, LiCF3SO3 as salt, and a variety of concentrations of nanochitosan as inert filler, succinonitrile as a solid non-ionic plasticizer has been prepared. The prepared membranes were subjected to X-ray diffraction, FT-IR, tensile strength, morphological studies, thermal analysis, AC ionic conductivity measurement, and interfacial analyses. The combined effect of succinonitrile and nanochitosan on the electrochemical properties of polymer electrolytes has been studied, and it was confirmed that the ionic conductivity is significantly increased. The maximum ionic conductivity of the plasticized nanocomposite polymer electrolytes are found to be in the range of 10?2.8?S/cm. Besides, the interfacial stability also shows a significant improvement. The tensile measurement and thermal analysis results illustrate that the electrolytes based on that polymer host possess good mechanical and thermal stabilities. 相似文献
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Wet acid oxidation treatment methods have been widely reported as an effective method to purify and oxidize the surface of industrial multi-walled carbon nanotubes. This work examines the use of a concentrated HNO3/H2SO4 mixture in an attempt to optimize the purification procedure of industrial multi-walled carbon nanotubes with diameter distribution statistics. It is shown that acid treatments of several hours are enough to purify the nanotubes. The electrical and thermal conductivities of epoxy composites containing 0.05–0.25 wt% of an acid-treated multi-walled carbon nanotube have been studied. The electrical conductivity of the composites decreases by more than three orders, whereas the thermal conductivity of the same specimen increases very modestly as a function of the filler content. 相似文献
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The lattice thermal conductivity of a non-crystalline polymer has been studied at low temperatures in the frame of the density fluctuation model by calculating the total lattice thermal conductivity of polyvinyl acetate in the temperature range 0.1–4K as an example and a very good agreement has been reported between the calculated and the experimental values of the lattice thermal conductivity in the entire temperature range of study. It is also found that at low temperatures, the lattice thermal resistivity of a non-crystalline polymer is mainly due to scattering of phonons by empty spaces. 相似文献
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The Role of Interfacial Layers in the Enhanced Thermal Conductivity of Nanofluids: A Renovated Maxwell Model 总被引:11,自引:6,他引:5
Nanofluids, a new class of solid/liquid suspensions, offer scientific challenges because their measured thermal conductivity is one order of magnitude greater than predictions. It has long been known that liquid molecules close to a solid surface form layered solid-like structures, but little is known about the connection between this nanolayer and the thermal properties of the suspensions. Here, we have modified the Maxwell equation for the effective thermal conductivity of solid/liquid suspensions to include the effect of this ordered nanolayer. Because this ordered nanolayer has a major impact on nanofluid thermal conductivity when the particle diameter is less than 10 nm, a new direction is indicated for development of next-generation coolants. 相似文献