Pressure-drop reduction and heat-transfer deterioration of slush nitrogen in horizontal pipe flow

Katsuhide Ohira, Kei Nakagomi, Norifumi Takahashi

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)

Abstract

Cryogenic slush fluids such as slush hydrogen and slush nitrogen are two-phase, single-component fluids containing solid particles in a liquid. Since their density and refrigerant capacity are greater than those of liquid-state fluid alone, there are high expectations for the use of slush fluids in various applications such as clean-energy fuels, spacecraft fuels for improved efficiency in transportation and storage, and as refrigerants for high-temperature superconducting equipment. Experimental tests were performed using slush nitrogen to obtain the flow and heat-transfer characteristics in two different types of horizontal circular pipes with inner diameters of 10 and 15 mm. One of the primary objectives for the study was to investigate the effect of pipe diameter on the pressure-drop reduction and heat-transfer deterioration of slush nitrogen according to changes in the pipe flow velocity, solid fraction and heat flux. In the case of an inner diameter of 15 mm, pressure drop was reduced and heat-transfer characteristics deteriorated when the pipe flow velocity was higher than 3.6 m/s. On the other hand, in the case of an inner diameter of 10 mm, pressure drop was reduced and heat-transfer characteristics deteriorated when the pipe flow velocity was higher than 2.0 m/s. From these results, it can be seen that a larger pipe diameter produces a higher onset velocity for reducing pressure drop and deteriorating heat-transfer characteristics. Furthermore, based on observations using a high-speed video camera, it was confirmed that pressure drop was reduced and heat-transfer characteristics deteriorated when the solid particles migrated to the center of the pipe and the flow pattern of the solid particles inside the pipe was pseudo-homogeneous.

Original languageEnglish
Pages (from-to)563-574
Number of pages12
JournalCryogenics
Volume51
Issue number10
DOIs
Publication statusPublished - 2011 Oct

Keywords

  • Heat-transfer deterioration
  • Hydrogen energy
  • Pressure-drop reduction
  • Slush nitrogen
  • Two-phase flow

ASJC Scopus subject areas

  • Materials Science(all)
  • Physics and Astronomy(all)

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