共查询到18条相似文献,搜索用时 156 毫秒
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对一种(内)衬钛钢管进行传热性能试验研究,主要通过对衬钛钢管和相同外径的光滑钢管进行对比传热试验,得出衬钛钢管的接触热阻,为其传热设计计算提供依据。采用套管式换热器的试件形式、通过管内外流体的对流换热进行试验。结果表明,衬钛管的平均传热系数约为光滑钢管的83.5%;衬钛管的平均接触热阻值为0.000 22(m2·℃)/W,接触热阻大小与管内外流体的换热温差有关。 相似文献
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涂层吸附床能够降低吸附剂间的热阻提高吸附床传热性能,是一种高效吸附床。文中采用COMSOL Multiphysics软件建立了局部非热平衡的二维板翅式吸附床模型,开展板翅式吸附床性能数值模拟;采用制冷性能(COP)和单位质量吸附剂制冷能力(SCP)分别对不同翅片形状吸附床(三角形翅片吸附床、梯形翅片吸附床与六边形翅片吸附床)的性能进行分析和评价。研究发现:驱动热源为333—363 K时,随着热源温度的升高,3种不同结构的板翅式涂层吸附床的COP和SCP都随之增大;在相同的条件下,3种不同翅片结构的板翅式吸附床中,六边形翅片吸附床的COP最大,其值为0.514;而梯形翅片吸附床的SCP最高,其值为848.61 W/kg。 相似文献
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Adsorbents are important components in adsorption refrigeration. The diameter of an adsorbent can af-fect the heat and mass transfer of an adsorber. The effect of particle diameter on effective thermal conductivity was investigated. The heat transfer coefficient of the refrigerant and the void rate of the adsorbent layer can also affect the effective thermal conductivity of adsorbents. The performance of mass transfer in the adsorber is better when pressure drop decreases. Pressure drop decreases with increasing permeability. The permeability of the adsorbent layer can be improved with increasing adsorbent diameter. The effect of adsorbent diameter on refrigeration output power was experimentally studied. Output power initially increases and then decreases with increasing diameter under different cycle time conditions. Output power increases with decreasing cycle time under similar diameters. 相似文献
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采用化学聚合法强化吸附剂——沸石颗粒的热传导性能,利用苯胺单体在沸石颗粒表面氧化聚合,使少量的聚苯胺形成均匀连续的导热性能好的高分子材料网,在实验条件下可使该种吸附剂的有效导热系数提高到原来的4倍多。同时,将强化后的吸附剂挤压成型,进行强化吸附床层的传热研究,结果表明堆积密度为原来的1.5倍的成型块,其有效导热系数比原来提高30%,对比混合法的实验和数据分析表明,化学聚合法较物理混合法效果更明显,是一种适宜吸附剂热传导强化的新途径。 相似文献
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M. Kwapinska 《Powder Technology》2008,181(3):331-342
Heating of free-flowing particles by contact with the wall of a rotary drum without inserts has been simulated in two dimensions by means of the thermal version of the Discrete Element Method (DEM). The results are in qualitative agreement with existing experimental data and with the classical penetration model (PM) for the following limiting cases: heat transfer controlled by a contact resistance at the wall of the drum; heat transfer to agitated beds with significant bed-side resistance; heat transfer to the stagnant bed. The latter can be used to establish an equivalence (calibration) between the discrete (DEM) and the continuous (PM) modelling approach. Thermal mixing times can be derived from asymptotic overall heat transfer coefficients obtained via thermal DEM for agitated beds. They are found to be significantly smaller than purely mechanical mixing times. For the investigated conditions, they are also much smaller than previous recommendations based on the PM. The ability of thermal DEM to provide information not accessible to the penetration model, like temperature distributions, is discussed. It is pointed out that a decrease of the high computational cost of the method is necessary in order to enhance its applicability. 相似文献
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热泵吸附器中传热传质过程的研究 总被引:11,自引:0,他引:11
对吸附式热泵循环系统中的传热传质进行了理论分析和实验研究,建立了吸附器中热传导方程.计算求解值与实验结果相一致,说明了吸附器中的传热速率控制了热泵循环速度.据此,对吸附器中强化传热肋片进行了模拟分析,作为吸附器优化设计的理论依据. 相似文献
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热管型船用吸附制冰机的设计 总被引:1,自引:1,他引:0
A heat pipe type adsorption ice maker with two adsorbers for fishing boats is designed by using ammonia as refrigerant and compound of activated carbon-CaCl2 as adsorbent. This type of heat pipe adsorber can solve the problem of incompatibility between ammonia, copper, seawater and steel. The working process of the ice maker with 8.7kg adsorbent per bed is simulated. The results show that the optimal semi-cycle time is about 9 min at the evaporating temperature of -15℃, where the corresponding cooling power, specific cooling power per kilogram adsorbent SCP and coefficient of refrigerant performance COP are respectively 3.6kW, 217W·kg-1 and 0.404. 相似文献
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研制了一种可以采用渔船柴油发动机余热加热的以复合吸附剂(CaCl2和活性炭)-氨为工质对的吸附式渔船制冰机.由于采用了复合交变分离热管原理,吸附制冰机解决了用海水直接冷却吸附床带来的腐蚀等问题.建立了小型渔船吸附制冰机试验装置,每个吸附床的复合吸附剂的质量为2.35 kg.试验研究表明,在两床循环中采用回热回质过程系统的制冷功率提高约103.8%,制冷系数(COP)提高了约为100%.在采用回热回质的条件下,制冰工况所得到的单位质量的氯化钙的制冷功率(SCP)约为281.9~712.8 W8226;kg-1,相对于目前国内外的研究成果,提高了1.4~3.5倍. 相似文献