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1.
改良六水氯化钙相变材料的制备及性能   总被引:1,自引:0,他引:1  
选取CaCl_2·6H_2O相变材料为研究对象,通过实验对相变材料的制备过程进行了优化改进,得到CaCl_2·6H_2O相变材料质量配比为43.39%H_2O+45.76%Ca Cl2+8.15%Sr Cl2·6H_2O+2.7%CMC,材料蓄放热稳定,无过冷度,无明显相分离现象,测得相变温度为28.6℃,相变潜热为169.5k J/kg。最优例材料经过100次循环稳定性测试后,相变温度降低了0.8℃,出现1.4℃的过冷度,但仍表现出良好的热稳定性。实验发现纳米粒子的添加对材料的导热性能有显著的提高,且当4种纳米粒子的质量百分数均为0.2%时,复合材料的导热系数大小依次为MWCNTCuAl_2O_3TiO_2,其中添加MWCNT的导热系数达到0.7480W/(m·K),比原材料导热系数提高了31.5%。  相似文献   

2.
制备了一种空调用相变蓄冷材料,该蓄冷材料由两种相变材料(辛酸和软脂酸)组成,通过加热搅拌的方法将其制备成均匀的共晶相变蓄冷材料,实验分析了所研制的蓄冷材料的相变点、相变潜热等性能。测试结果表明该相变蓄冷材料具有适宜的相变温度和较高的相变潜热,可用作空调蓄冷材料。  相似文献   

3.
蓄冷球堆积床动态充冷性能模拟   总被引:1,自引:0,他引:1  
根据蓄冷球和载冷剂之间的能量平衡,建立了蓄冷球堆积床充冷过程的数理模型。该模型考虑了载冷剂与蓄冷球之间的换热系数变化、载冷剂的导热、相变蓄冷材料的过冷度以及蓄冷球堆积床热损失的影响。采用数值计算方法模拟了蓄冷球堆积床的充冷过程,讨论了载冷剂入口温度、初始温度和流速对充冷过程蓄冷材料温度、载冷剂温度和蓄冰率的影响。  相似文献   

4.
空调蓄冷材料研究现状及其新进展   总被引:4,自引:0,他引:4  
分析了空调蓄冷材料研究现状及存在的一些问题 ,提出研制一种新型空调复合蓄冷材料 ,通过实验 ,分析该蓄冷材料的融点、融解热等热学性能。并通过实验研究寻找到了一种新型空调蓄冷材料 ,测试结果表明该蓄冷材料具有较高的相变潜热、适宜的相变温度和较好的热稳定性 ,因此可被应用于蓄冷空调系统中。  相似文献   

5.
蔡迪  李静  焦乃勋 《物理学报》2019,68(10):100502-100502
本文分别制备了纳米石墨烯片质量分数为0%, 0.5%, 1%, 1.5%, 2%的纳米石墨烯片-正十八烷复合相变材料,并通过扫描电镜测试、红外光谱分析、差示扫描量热实验及导热分析等实验对其形貌结构及热物性进行表征和研究.实验表明本文制备的纳米石墨烯-正十八烷复合相变材料具有很好的相变稳定性;当纳米石墨烯片的质量分数达到2%时,复合相变材料的导热系数相对于纯十八烷高出了89.4%.  相似文献   

6.
复合低温相变蓄冷材料的实验研究   总被引:3,自引:0,他引:3  
提出自行研制的一种复合低温相变蓄冷材料,通过实验分析了该蓄冷材料的融点、相变潜热和凝固融化过程曲线.该材料由有机物和无机物混合而成,用示差扫描量热仪(DSC)来测定该蓄冷材料的融点、相变潜热;用低温冰箱测试凝固融化过程材料的均匀稳定性.实验结果表明,该材料具有良好的性能,适用于医药、食品、冰箱及冷库等蓄冷装置中.  相似文献   

7.
移动供热技术的关键在于蓄热材料。针对当前移动供热技术中,相变材料导热系数低、相变温度低、放热不稳定等不足,本文设计开发了一种新型纳米复合蓄热相变材料。研究了纳米铜、纳米锌、纳米铁、纳米镍和纳米铝对赤藻糖醇的蓄热性能影响,运用时间曲线法确定纳米铜作为基材的添加物。采用超声振荡预处理和添加分散剂等方法,发现按1:1添加的油酸与十二烷基硫酸钠二元混合物8 h无沉降。对纳米铜质量分数不同的六个纳米铜赤藻糖醇样本材料性能进行测定,结果表明添加0.4%的纳米铜赤藻糖醇过冷度下降89.5%,潜热值下降0.3%,固态、液态导热系数分别增大2.8倍和3.3倍。  相似文献   

8.
本实验通过添加四种不同表面活性剂,分析对Al_2O_3-H_2O纳米流体热物性特性的影响,加入SDBS、SDS和PVP的Al_2O_3-H_2O过冷度分别下降20.17%、6.19%和3.18%,导热系数分别下降2.94%、4.63%和3.71%,相变时间分别延长4.40%、8.60%和6.18%。但添加TEA表面活性剂,反使得Al_2O_3-H_2O纳米流体的过冷度提高12.57%,导热系数下降6.33%,相变时间延长了15.05%。由于四种表面活性剂的影响,使得Al_2O_3-H_2O纳米流体的热导率均下降,相变时间延长。在一定浓度范围内,表面活性剂对相变潜热值的影响基本保持在6%的波动范围内,可认为少量表面活性剂对相变潜热值没有影响,但其相变曲线有较大的差异性。  相似文献   

9.
本文通过将纳米氧化锌(ZnO)颗粒加入熔融的石蜡(PW)并进行搅拌和超声制备了一种纳米ZnO/PW复合相变储能材料。为使纳米氧化锌在基体物质中分散均匀,在制备过程中使用了搅拌和超声以制备均匀的复合材料。使用扫描电镜观察其微观结构表明氧化锌在石蜡中分散良好。对所得ZnO/PW复合相变材料的相变温度、相变焓及导热系数等热物...  相似文献   

10.
《低温与超导》2021,49(5):84-90
针对传统的飞机地面空调车存在不能以小功率用电保障大功率需求及冷量损失严重等问题,提出一种相变蓄冷式飞机地面空调车,简要分析了系统组成及其原理,对蓄、释冷系统进行了实验研究。结果表明:蓄冷工况下相变蓄冷材料在-2℃开始相变,蓄冷量达到200 kW时耗时38 min,蓄冷3 h蓄冷量为950 kW;释冷工况下蓄冷箱的释冷时间大于2 h,当进风温度为27℃、湿度为32%左右时出风温度为4℃、湿度为94%左右,出风压力及风量均在设计范围之内,设计合理。  相似文献   

11.
Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.  相似文献   

12.
A simple technique of pulse compression, based on the linear chirp compensation of self-phase modulation (SPM) spectra in dispersion shifted fibers, is demonstrated. The optimization procedure is carried out, for a short span of a single-mode fiber, using a parabolic law, which describes the behavior of the squared output pulse width versus the pump peak power in the case of Gaussian pulses. The experimental results give a minimum pulse duration of 233 fs, which is in good agreement with the model. Shorter and coherent pulses, down to 90 fs, have been obtained by inserting an interference filter at the optical output.  相似文献   

13.
The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper.  相似文献   

14.
Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·104 Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.  相似文献   

15.
16.
A review of schemes for multiple access in fiber optic networks shows that a hybrid of wavelength and code division multiple access (WCDMA) combines the best features of both. In particular, the hybrid scheme retains the large information carrying capacity of wavelength division multiple access (WDMA) and flexibility of code division multiple access (CDMA). In this paper WDMA, optical CDMA (OCDMA), and WCDMA networks are discussed. In OCDMA networks, concept of incoherent and coherent coding including inverse decoding and matched filter is introduced. The delay performance of both WDMA and WCDMA networks, under the simple suboptimum access protocols based on cyclic search, is computed. It has been shown quantitatively that tuning delay significantly affects the delay performance of both WDMA and WCDMA networks. Futhermore, delay performance of WCDMA networks is always better than the WDMA networks for the same tuning delay, load, and number of users.  相似文献   

17.
A transient suppression method for piezoelectric ceramic transducer is presented. By adding some special pedestal pulses to the original transmitted signal, the transient effects in the output of the transducer can be just precisely transmission by use of a narrowband transducer. canceled, thereby achieving the broadband The experimental results show that the transient responses of the sinusoid pulses and coded signals are suppressed successfully and the acoustic waveforms radiated into the surrounding water are improved significantly.  相似文献   

18.
We experimentally demonstrate amplitude squeezed soliton utilizing intensity-dependent self-phase modulation in an asymmetric Sagnac interferometer.The system.whose components are connected via ferrule connector/physical connection(FC/PC)fiber connectors,constitutes all-fiber configuration to generate squeezed soliton.Soliton amplitude reduction measured by homodyne detection is near 4.0 dB below the shot-noise level.Optimal squeezing fields in both simple and compact all-fiber configuration are obtained.  相似文献   

19.
The(2 1)-dimensional nonlinear Schr(o)dinger(NLS)equation with spatially inhomogeneous nonlinearities is investigated,which describes propagation of light in(2 1)-dimensional nonlinear optical media with inhomogeneous nonlinearities.New types of optical modes and nonlinear effects in optical media are presented numerically.The results reveal that the regular split of beam can be obtained in (2 1)-dimensional nonlinear optical media with inhomogeneous nonlinearities,by adjusting the guiding parameter.Furthermore,the stability of beam regular split is discussed numerically,and the results reveal that the beam regular split is stable to the finite initial perturbations.  相似文献   

20.
In the real-world application of face recognition system, owing to the difficulties of collecting samples or storage space of systems, only one sample image per person is stored in the system, which is so-called one sample per person problem. Moreover, pose and illumination have impact on recognition performance. We propose a novel pose and illumination robust algorithm for face recognition with a single training image per person to solve the above limitations. Experimental results show that the proposed algorithm is an efficient and practical approach for face recognition.  相似文献   

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