共查询到19条相似文献,搜索用时 93 毫秒
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详细总结了微通道换热器的研究进展以及发展前景;概括阐述了微通道换热器具有的常规尺寸设备所无可比拟的优越性;从节约能源和占地面积的角度分析了微通道换热器的应用领域及前景. 相似文献
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为满足电子电路、燃料电池、激光器等精密仪器及器件的持续高效散热需求,本文设计了一种基于冲击流动的分流式正弦型微通道换热器,传热效率更高,压降损失更小,加工工艺更简单。本研究主要通过热–流–固耦合的数值模拟方法,对比了微通道宽度、深度、形状及分流结构对换热器传热和流动特性的影响。模拟结果表明:带有8个分流通道的分流式正弦型微通道换热器的综合性能最好,微通道长、宽、深尺寸为30 mm×0.4 mm×2.5 mm,在冷却液流量为0.6 mL·s-1时,总热阻为0.247?C·W-1。在实际工作中,换热器总热阻为0.395?C·W-1,压降损失也较小,所得实验结果与模拟结果基本吻合,相比于预设计的换热器和大通道换热器,优化后的正弦型微通道换热器在传热和流动性能方面均获得了显著提升。 相似文献
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Heat transfer characteristics of a gas-to-gas counterflow microchannel heat exchanger have been experimentally investigated. Temperatures and pressures at inlets and outlets of the heat exchanger have been measured to obtain heat transfer rates and pressure drops. The heat transfer and the pressure drop characteristics are discussed. Since the partition wall of the heat exchanger is thick compared with the microchannel dimensions, a simple heat exchange model with constant wall temperature is proposed to predict the heat transfer rate. The predicted heat transfer rate using the constant wall temperature model agrees well with the experimental results. 相似文献
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Presented are results of an experimental study of local heat transfer characteristics in boiling of the dielectric liquid perfluorohexane under forced convection in a horizontal microchannel heat exchanger. The experiments with a copper microchannel heat exchanger comprising 21 channels with sections of 335 × 930 μm were conducted with a mass velocity of 250 to 1000 kg/m2s and a heat flux through the outer wall of the heat exchanger of 3 to 60 W/cm2. The dependence of the local heat transfer coefficient on the heat flux density on the inner wall of the microchannels was established, as well as the critical heat flux. The experimental data are compared with calculations based on known models of heat transfer. 相似文献
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A. G. Agwu Nnanna 《实验传热》2013,26(2):157-173
This article presents an experimental study of thermo-hydrodynamic phenomena in a microchannel heat exchanger system. The aim of this investigation is to develop correlations between flow/thermal characteristics in the manifolds and the heat transfer performance of the microchannel. A rectangular microchannel fabricated by a laser-machining technique with channel width and hydraulic diameter of 87 μm and 0.17 mm, respectively, and a trapezoidal-shaped manifold are used in this study. The heat sink is subjected to iso-flux heating condition with liquid convective cooling through the channels. The temporal and spatial evolutions of temperature as well as total pressure drop across the system are monitored using appropriate sensors. Data obtained from this study were used to establish relationships between parameters such as longitudinal wall conduction factor, residence and switching time, and thermal spreading resistance with Reynolds number. Result shows that there exist an optimum Reynolds number and conditions for the microchannel heat exchanger system to result in maximum heat transfer performance. The condition in which the inlet manifold temperature surpasses the exit fluid temperature results in lower junction temperature. It further shows that for a high Reynolds number, the longitudinal wall conduction parameter is greater than unity and that the fluid has sufficient dwelling time to absorb heat from the wall of the manifold, leading to high thermal performance. 相似文献
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In this work, a double-layered microchannel heat exchanger is designed for investigation on gas-to-gas heat transfer. The micro-device contains 133 parallel microchannels machined into a polished polyether ether ketone plate for both the hot side and cold side. The microchannels are 200 μm high, 200 μm wide, and 39.8 mm long. The design of the micro-device allows tests with partition foils in different materials and of flexible thickness. A test rig is developed with the integration of customized pressure and temperature sensors for in situ measurements. Experimental tests on the counter-flow micro heat exchanger have been carried out for five different partition foils and various mass flow rates. The experimental results, in terms of pressure drop, heat transfer coefficients, and heat exchanger effectiveness are discussed and compared with the predictions of the classic theory for conventionally sized heat exchangers. 相似文献
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随着高效预冷器在航天航空领域发挥越来越重要的作用,紧凑高效换热器的研究成为了人们关注的热点。本文基于紧凑微通道换热器的几何特征,针对矩形截面平行流道换热器内超临界压力低温流体(氢和氦)在大温差条件下的流动换热现象进行数值模拟研究。通道截面边长小于1 mm,热流体氦和冷流体氢的进出口温差均大于600 K。通道内流体换热系数在顺流和逆流条件下有不同的变化趋势,并出现峰值。换热量随着通道宽度的增大而增大,流动压降随着通道宽度的增大而减小。冷热流体逆流时换热量大,压降较小,但对换热器材料要求较高。 相似文献
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随着高效预冷器在航天航空领域发挥越来越重要的作用,紧凑高效换热器的研究成为了人们关注的热点。本文基于紧凑微通道换热器的几何特征,针对矩形截面平行流道换热器内超临界压力低温流体(氢和氦)在大温差条件下的流动换热现象进行数值模拟研究。通道截面边长小于1 mm,热流体氦和冷流体氢的进出口温差均大于600 K。通道内流体换热系数在顺流和逆流条件下有不同的变化趋势,并出现峰值。换热量随着通道宽度的增大而增大,流动压降随着通道宽度的增大而减小。冷热流体逆流时换热量大,压降较小,但对换热器材料要求较高。 相似文献
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高密度、 小体积和高集成的电子元器件散热困难, 易造成过早失效, 采用微通道换热器可以实现小体积内高热流的散热, 但流动阻力很大. 为了保证传热效果, 降低流动阻力, 本文提出了一种新型的微通道结构并对其流动与传热特性进行了数值模拟. 首先研究了微通道形状和结构, 模拟结果表明: 进出口截面宽高比为0.8 的矩形微通道的换热效果最好; 并在此基础上提出一种康托尔分型凹槽结构, 研究了有无康托尔分形以及不同分形级数对流动与传热性能的影响, 综合对比发现: 第二级康托尔分形模型 N2 既能保证热阻显著降低, 又能相比阵列结构降低压降, 具有明显的换热优势; 最后对这种康托尔分形结构的凹槽形状, 尺寸及不同方向上的分形进行研究, 结果表明梯形凹槽的下上表面长度比b/a 为0.6 、 流动方向分形比fx 为1 .25 和通道高度方向分形比fy 为1 .5 时换热流动性能最佳. 相似文献
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In this paper, an analytical method of microchannel heat exchanger characteristics optimization is described. An objective function that combines thermal-hydraulic and constructive parameters of a heat-exchanger such as number, diameter, and length of channels, was developed. Limitations on its application were determined. Influence of these parameters on the function’s value was analyzed. It is demonstrated that for each fixed amount of microchannels and its length, an optimal channel diameter exists. Formulas for optimal ratio of length, diameter, and number of microchannels evaluation were derived. It was shown that the maximum value of the objective function corresponds to a thin heat exchange matrix that consists of a large number of short channels with small diameter. 相似文献
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作为一种新型微通道换热器,印刷电路板式换热器(Printed Circuit Heat Exchanger, PCHE)因比表面积大、耐高压和低温、海上适应性强以及便于模块化等特点,近年来逐渐成为浮式LNG接收站和浮式储存及再气化装置的主低温换热器首选。针对改进后的错列S型翅片,对超临界LNG在翅片通道内的流动传热特性展开数值模拟,并重点探析拟临界工况附近的对流换热特征。结果表明,错列S形翅片能在保证良好的传热性能下获得较低的阻力压降;在LNG-丙烷中间介质气化器内,随着超临界LNG压力的升高,能带来更高的出口温度,沿流通长度方向上定压比热的变化也趋于平缓,而变化过渡区也会逐渐趋于温度更高的流场区,同时定压比热变化的极大值也会大幅缩小;入口段的温度场变化梯度明显,且变化梯度会随着压力提高而进一步增大;在靠近拟临界压力处,超临界LNG在翅片流道中会由于物性剧烈变化而出现传热异常行为。 相似文献