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Heat transfer and pressure drop characteristics of flow boiling in a horizontal deep spirally fluted tube.

Author(s) : MCBAIN S. M., BERGLES A. E., RAINA S.

Type of article: Article

Summary

Few studies exist that have investigated flow boiling in deep spirally fluted enhanced heat transfer tubing. The experiment seeks to determine the local heat transfer coefficient and pressure gradient for flow boiling of R12 and R134a in a horizontal, deep spirally fluted copper tube. Effects of local quality, mass flux, and heat flux were investigated. The reduced data clearly show nucleate boiling and bulk convective regimes at low and high qualities, respectively. For a performance evaluation, the data were compared to a smooth tube with a diameter equivalent to the envelope diameter of the fluted tube. Smooth tube heat transfer was represented by the Kandlikar (1989) correlation, and smooth tube pressure drop was determined from a homogeneous model. The results showed that the fluted tube has a heat transfer enhancement in the nucleate regime ranging from 1.5 to 2.7 with R12, and from 1.4 to 2.5 from R134a. In the convective regime there was a more substantial increase, with enhancements ranging from 3.5 to 7.6 with R12, and from 3.3 to 7.1 with R134a. R134a had up to a 50% higher heat transfer coefficient than R12. The pressure drop was found to be 6 to 20 times greater than a smooth tube with R12, and 11 to 19 times greater with R134a.

Details

  • Original title: Heat transfer and pressure drop characteristics of flow boiling in a horizontal deep spirally fluted tube.
  • Record ID : 1998-0129
  • Languages: English
  • Source: HVAC&R Research - vol. 3 - n. 1
  • Publication date: 1997/01
  • Document available for consultation in the library of the IIR headquarters only.

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