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Multiphase Science and Technology

Publicou 4 edições por ano

ISSN Imprimir: 0276-1459

ISSN On-line: 1943-6181

SJR: 0.144 SNIP: 0.256 CiteScore™:: 1.1 H-Index: 24

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HEAT TRANSFER AND FLOW CHARACTERISTICS OF A NON-UNIFORMLY HEATED TUBE UNDER LOW PRESSURE AND LOW MASS FLUX CONDITION

Volume 18, Edição 4, 2006, pp. 387-412
DOI: 10.1615/MultScienTechn.v18.i4.40
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RESUMO

In an actual boiling channel, the circumferential heat flux is not uniform. Thus, the understanding of the heat transfer characteristics of non-uniformly heated tube becomes an important design factor for conventional boilers, especially for the compact water-tube boiler with tube-nested combustor. The small compact boiler is operated at low-pressure and low-mass flux condition compared with the large scale boiler, so that the non-uniformity in heat flux may strongly affect the heat transfer characteristics. In this investigation, non-uniform heat flux distribution along the circumferential direction was generated by using Joule heating of SUS304 eccentric tubes. The heated length of test-section was 900mm, inner diameter was 20mm, and outer diameter was 24mm. The eccentricity of the tube was s = 0, 0.5, 1.0 and 1.5mm. Corresponding maximum/minimum heat fluxes rations were 1.0, 1.7, 3.0 and 7.0, respectively. Experiments were conducted for upward and downward flows, with system pressures 0.3 and 0.4MPa, mass flux range 10-100kg/m2s and inlet temperatures 30 and 80deg.C. The eccentricity resulted in an increase in the CHF of the upward flow, while the effect was hardly observed in the downward flow. The effect of eccentricity on the CHF was well interpreted by the liquid film redistribution. In this paper, the local heat transfer coefficient along the circumferential direction was also presented.

CITADO POR
  1. Ami Takeyuki, Umekawa Hisashi, Ozawa Mamoru, Mishima Kaichiro, Saito Yasushi, CHF in a circumferentially non-uniformly heated tube under low-pressure and low-mass-flux condition (inclined upward flow), Heat Transfer-Asian Research, 40, 2, 2011. Crossref

  2. AMI Takeyuki, UMEKAWA Hisashi, OZAWA Mamoru, MISHIMA Kaichiro, SAITO Yasushi, CHF in a Non-Uniformly Heated Tube under Low-Pressure and Low-Mass-Flux Condition : Influence of Angle of Inclined Upward Flow(Thermal Power Plant and Thermal-Hydraulics,<Special Issue>Power and Energy System Symposium), Transactions of the Japan Society of Mechanical Engineers Series B, 75, 751, 2009. Crossref

  3. AMI Takeyuki, UMEKAWA Hisashi, OZAWA Mamoru, MISHIMA Kaichiro, SAITO Yasushi, CHF in a Circumferentially Non-Uniformly Heated Tube under Low-Pressure and Low-Mass-Flux Condition : Inclined Upward Flow(<Special Issue>Challenge to Ultimate Cooling Technique Using Phase Change Process), Transactions of the Japan Society of Mechanical Engineers Series B, 75, 758, 2009. Crossref

  4. AMI Takeyuki, UMEKAWA Hisashi, OZAWA Mamoru, MISHIMA Kaichiro, SAITO Yasushi, , JAPANESE JOURNAL OF MULTIPHASE FLOW, 22, 4, 2008. Crossref

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