共查询到17条相似文献,搜索用时 102 毫秒
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提出了一种制取片冰的新方法并建立了实验装置;对装置的融冰过程进行了实验研究,考察了蓄冰槽出口水温随时间的变化关系,并计算了蓄冰槽的放冷速率。研究结果表明,该蓄冷装置在融冰取冷时,具有出水温度低、放冷速率大的特点,尤其适合于如影剧院、大会堂、体育馆等短时间需要大量冷量的冰蓄冷空调系统。 相似文献
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《制冷》2017,(2)
随着人们生活水平的提高,对食品品质的要求也不断的提高,尤其是果蔬的新鲜度。蓄冷运输是解决冷链断链的有效措施。Al_2O_3-H_2O纳米流体蓄冷材料制备时采用低密度海绵来吸附纳米流体中的纳米颗粒,抵御重力作用造成纳米颗粒的沉淀,以达到较长时间的稳定。采用堆码实验,以胡萝卜为实验对象,分析Al_2O_3-H_2O纳米流体蓄冷材料堆码方式(五种),蔬菜预冷温度(-1℃、4℃、13℃),蓄冷材料的质量(5.1kg、4.6kg、3.0kg、2.4kg、1.5kg),三种因素对Al_2O_3-H_2O纳米蓄冷包装箱蓄冷效果的影响。研究结果表明:果蔬不同预冷温度使蓄冷箱中恒温区域明显不同,其中恒温区域ⅠⅡⅢ;对于同一预冷温度下五种堆码方式下的果蔬温度趋势基本一致,且保鲜时间堆码方式12345;对于存放相同质量胡萝卜的蓄冷箱中蓄冷材料质量越大保温效果越好,在实际中可根据保温时间选择合适的预冷温度。该实验方法及结果具有指导借鉴作用,可以为后期的实验及分析提供理论基础。 相似文献
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DSC法测量低温相变蓄冷纳米流体的比热容 总被引:1,自引:0,他引:1
介绍差示扫描量热仪(DSC)测量液体比热容的原理和方法,并测量4种不同体积分数的TiO2-Ba-Cl2-H2O纳米流体比热容。结果表明,加入纳米粒子后其比热容都有所降低,并随TiO2体积分数的增大而逐渐减小。 相似文献
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Huaqing XIE Jifen WAN Lifei CHEN 《材料科学技术学报》2008,24(5):742-744
Nanofluids have been demonstrated to have intriguing thermodynamic properties. In this work, we described the investigation of the phase transformation behaviors of nanofluids containing alumina (Al2O3) or titania (TiO2) nanoparticles with different weight fractions. The experimental results indicate that the melting temperatures of nanofluids (in freezing states) are reduced with the increase of the weight fraction of nanoparticles. The reduction is related to nanoparticle species as well as nanoparticle size. 相似文献
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Heat and mass transfer enhancement of binary nanofluids for H2O/LiBr falling film absorption process
The objectives of this study are to measure the vapor absorption rate and heat transfer rate for falling film flow of binary nanofluids, and to compare the enhancement of heat transfer and mass transfer under the same conditions of nanofluids. The key parameters are the base fluid concentration of LiBr, the concentration of nanoparticles in weight %, and nanoparticle constituents. The binary nanofluids are H2O/LiBr solution with nanoparticles of Fe and Carbon nanotubes (CNT) with the concentrations of 0.0, 0.01 and 0.1 wt %. The vapor absorption rate increases with increasing the solution mass flow rate and the concentration of Fe and CNT nanoparticles. It is found that the mass transfer enhancement is much more significant than the heat transfer enhancement in the binary nanofluids with Fe and CNT. It is also found that the mass transfer enhancement from the CNT nanoparticles becomes higher than that from the Fe nanoparticles. Therefore, the CNT is a better candidate than Fe nanoparticles for absorption performance enhancement in H2O/LiBr absorption system. 相似文献
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以钛酸四丁酯为原料,在水/丁醇界面区进行水解,制备了锐钛矿型TiO2。分别将不同量的TiO2分散在水相或油相中,以界面聚合方法制备了TiO2/聚酰胺反渗透复合膜,研究了TiO2含量对所制备复合膜结构和分离性能的影响。SEM图谱结果表明,当TiO2添加到水相中时,其同时存在于聚酰胺复合膜皮层的底层以及聚砜基膜的指状孔道中;当TiO2添加到油相中时,复合膜表面结构致密,峰谷结构明显,可看到在膜皮层的表面有TiO2存在。膜分离性能的研究结果表明,与TiO2添加在水相中相比,TiO2添加在油相中能更好地提高膜分离性能。膜抑菌性能研究表明TiO2/聚酰胺反渗透膜在紫外光照下对大肠杆菌表现出良好的杀灭性能。 相似文献
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This paper presents measurements of the thermal conductivity and the dynamic viscosity of $\mathrm{Al}_{2}\mathrm{O}_{3}$ Al 2 O 3 –ethylene glycol and $\mathrm{TiO}_{2}$ TiO 2 –ethylene glycol (1 % to 3 % particle volume fraction) nanofluids carried out in the temperature range from $0\,^{\circ }$ 0 ° C to $50\,^{\circ }$ 50 ° C. The thermal-conductivity measurements were performed by using a transient hot-disk TPS 2500S apparatus instrumented with a 7577 probe (2.001 mm in radius) having a maximum uncertainty $(k=2)$ ( k = 2 ) lower than 5.0 % of the reading. The dynamic-viscosity measurements and the rheological analysis were carried out by a rotating disk type rheometer Haake Mars II instrumented with a single-cone probe (60 mm in diameter and $1^{\circ }$ 1 ° ) having a maximum uncertainty $(k=2)$ ( k = 2 ) lower than 5.0 % of the reading. The thermal-conductivity measurements of the tested nanofluids show a great sensitivity to particle volume fraction and a lower sensitivity to temperature: $\mathrm{TiO}_{2}$ TiO 2 –ethylene glycol and $\mathrm{Al}_{2}\mathrm{O}_{3}$ Al 2 O 3 –ethylene glycol nanofluids show a thermal-conductivity enhancement (with respect to pure ethylene glycol) from 1 % to 19.5 % and from 9 % to 29 %, respectively. $\mathrm{TiO}_{2}$ TiO 2 –ethylene glycol and $\mathrm{Al}_{2}\mathrm{O}_{3}$ Al 2 O 3 –ethylene glycol nanofluids exhibit Newtonian behavior in all the investigated temperature and particle volume fraction ranges. The relative viscosity shows a great sensitivity to the particle volume fraction and weak or no sensitivity to temperature: $\mathrm{TiO}_{2}$ TiO 2 –ethylene glycol and $\mathrm{Al}_{2}\mathrm{O}_{3}$ Al 2 O 3 –ethylene glycol nanofluids show a dynamic viscosity increase with respect to ethylene glycol from (4 to 5) % to 30 % and from 14 % to 50 %, respectively. Present experimental measurements were compared both with available measurements carried out by different researchers and computational models for thermophysical properties of nanofluids. 相似文献