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综述了中草药提取分离工艺中高新技术的应用进展,包括超临界流体萃取、大孔树脂吸附分离、膜提取分离、超声波提取、高速逆流色谱提取、微波萃取等,并展望其对牙膏工业的促进和发展。 相似文献
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Experimental and numerical investigations have been conducted to study turbulent flow of water and heat transfer characteristics in a rectangular channel with discontinuous crossed ribs and grooves.The tests investigated the overall heat transfer performance and friction factor in ribbed and ribbed-grooved channels with rib angle of 30°.The experimental results show that the overall thermo-hydraulic performance for ribbed-grooved channel is increased by 10%-13.6% when compared to ribbed channel.The investigation on the effects of different rib angles and rib pitches on heat transfer characteristics and friction factor in ribbed-grooved channel was carried out using Fluent with SST(shear-stress transport) k-ω turbulence model.The numerical results indicate that the case for rib angle of 45° shows the best overall thermo-hydraulic performance,about 18%-36% higher than the case for rib angle of 0°.In addition,the flow patterns and local heat transfer characteristics for ribbed and ribbed-grooved channels based on the numerical simulation were also analyzed to reveal the mechanism of heat transfer enhancement. 相似文献
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板式蒸发式冷凝器是在蒸发式冷凝器和板式换热器的基础上发展起来的,兼有两者的优势.文中提出了一种用于计算蒸发式冷凝器气-液界面的温度和蒸发量的简化算法,进而对影响蒸发式冷凝器性能的参数进行了分析.结果显示,高的空气流速导致低的界面温度和高的蒸发量,强化了换热效果,并得到了空气通道内温度和含湿量的分布曲面;当相对湿度保持不变而增大空气温度时,蒸发量随之下降,与此同时界面温度线性上升. 相似文献
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利用Realizable k-ε湍流模型对带缺口的梯形扰流片进行流动和传热特性的数值模拟,研究了梯形扰流片的缺口位置及流动方式对矩形通道内流场以及传热的影响,同时通过对涡量、流线、流速分布、压力变化、湍流强度等的分析,揭示了扰流片强化传热的机理。结果表明,逆流时Nusselt数比顺流时提高了21.7%,同时摩擦因子也提高了25%。顺流时内侧缺口绕流片提高了传热系数的同时也增加了摩擦阻力,而外侧缺口的绕流片降低了传热系数同时也降低了形状阻力。研究发现较低Reynolds数下(10000相似文献
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为了解扩散燃烧中燃烧器的结构与火焰长度之间的关系,在前人工作的基础上,以双燃料喷口为研究对象,研究火焰长度随喷口间距变化的规律.研究表明:当喷口间距在0.5~2.0倍喷口直径范围内变化时,如果燃气速度一定,火焰长度将随喷口间距发生周期性的改变,变化的周期约为0.5个喷口直径;同流空气速度的大小对火焰长度变化周期的影响不明显. 相似文献
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