Critical heat flux in non-uniformly heated tube under low-pressure and low-mass-flux condition
Critical heat flux in non-uniformly heated tube under low-pressure and low-mass-flux condition
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低压低质量通量条件下非均匀加热管的临界热通量
DOI：
10.1002/htj.20095
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发表时间：
2006
期刊：
影响因子：
--
通讯作者：
Yasushi Saito
中科院分区：
文献类型：
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作者：
H. Umekawa;Tetsuo Kitajima;M. Hirayama;M. Ozawa;K. Mishima;Yasushi Saito
在实际的沸腾通道中，例如锅炉水管，周向热流是不均匀的。因此，非均热管的临界热流密度(CHF)成为常规锅炉的一个重要设计因素，特别是对于具有管式燃烧器的紧凑型水管锅炉。与大型锅炉相比，小型紧凑型锅炉在低压力、低质量流量条件下运行，液膜再分布对CHF特性有很大影响。采用焦耳加热的方法，对壁厚分布的SUS304管材进行了热流密度沿周向的非均匀分布。试验段加热长度900 mm，内径20 mm，外径24 mm。内管表面中心偏离外管表面中心e=0、0.5、1.0、1.5 mm。这些管子的最大热流密度与最小热流密度之比分别为1.0、1.7、3.0和7.0。实验条件为：系统压力为0.3和0.4 MPa，质量流量为10-100 kg/(M2s)，进口温度为30°和80°。实验结果表明，流动重分布的存在使临界热流密度增加。用一个类似于巴特沃斯扩散模型的概念解释了这些特征。《威利期刊》杂志，35(1)：47-60,2006；在线发表在《威利国际科学》(www.intercience.wiley.com)上。DOI 10.1002/htj.20095
In an actual boiling channel, e.g., a boiler water-tube, the circumferential heat flux is not uniform. Thus, the critical heat flux (CHF) of a non-uniformly heated tube becomes an important design factor for conventional boilers, especially for a compact water-tube boiler with a tube-nested combustor. A small compact boiler is operated under low-pressure and low-mass-flux conditions compared with a large-scale boiler, thus the redistribution of liquid film strongly affects the characteristics of CHF. In this investigation, non-uniform heat flux distribution along the circumferential direction was generated by using the Joule heating of SUS304 tubes with the wall thickness distribution. The heated length of test-section was 900 mm with an inner diameter of 20 mm and an outer diameter of 24 mm. The center of the inner tube surface was shifted by e=0, 0.5, 1.0, 1.5 mm from the center of the outer tube surface. The heat flux ratio between maximum and minimum heat flux of these tubes corresponded to 1.0, 1.7, 3.0, and 7.0, respectively. The experimental conditions were as follows: system pressure at 0.3 and 0.4 MPa, mass flux of 10–100kg/(m2s), inlet temperatures at 30° and 80°. The experimental results showed an increase in the critical heat flux substantiated by the existence of the redistribution of the flow. These characteristics are explained by using a concept similar to that of Butterworth's spreading model. © 2005 Wiley Periodicals, Inc. Heat Trans Asian Res, 35(1): 47–60, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20095