IIR document

Heat transfer characteristics in compact scraped surface ice slurry generators.

Author(s) : STAMATIOU E., KAWAJI M.

Summary

Current ice slurry generator systems demand a custom evaporator design and the use of mechanical devices such as scraper blades, orbital rods or impacting solid particles to maintain a freeze-free surface permitting the continuous ice slurry production. Such ice slurry generators are reported to have high capital costs and low thermodynamic efficiencies relative to conventional HVAC equipment restricting the use of ice slurries on markets outside North America. For existing ice slurry generators to be competitive with HVAC technologies, new ice slurry generators must be developed that can offer energy, space and capital cost savings. The development of compact and energy efficient ice slurry generator systems requires good knowledge of the scraped-surface heat transfer coefficient for ice slurries, accompanied by phase change, which is currently lacking. Until now, there have been very few investigations that have measured the scraped-surface heat transfer coefficients for the ice slurry production and no meaningful heat transfer correlations exist that account for both forced-convective crystallization and agitation because of the complex nature of the fluid mechanical and heat transfer processes involved. In the paper, local ice slurry heat transfer coefficients data were obtained in a vertically scraped, flat surface ice slurry generator that was chilled on its backside by an evaporating R404A refrigerant. The ice slurry mass flow rate ranged from 0.2 to 1.2 kg/s, axial Reynolds number from 500 to 4000, scraper Reynolds numbers 0 to 5000, and weight ice fractions 0 to 10%. The average heat transfer results suggest that the combined effects of agitation and phase change must be considered during the ice slurry production.

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Details

  • Original title: Heat transfer characteristics in compact scraped surface ice slurry generators.
  • Record ID : 2005-0180
  • Languages: English
  • Source: 21st IIR International Congress of Refrigeration: Serving the Needs of Mankind.
  • Publication date: 2003/08/17

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