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Heat Transfer and Pressure Drop Characteristics of Flow Boiling in a Horizontal Deep Spirally Fluted Tube
Few studies exist that have investigated flow boiling in deep spirally fluted enhanced heat transfer tubing. This experiment seeks to determine the local heat transfer coefficient and pressure gradient for flow boiling of R-12 and R-134a 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 R-12, and from 1.4 to 2.5 with R-134a. In the convective regime there was a more substantial increase, with enhancements ranging from 3.5 to 7.6 with R-12, and from 3.3 to 7.1 with R-134a. R-134a had up to a 50% higher heat transfer coefficient than R-12. The pressure drop was found to be 6 to 20 times greater than a smooth tube with R-12, and 11 to 19 times greater with R-134a.
Heat Transfer and Pressure Drop Characteristics of Flow Boiling in a Horizontal Deep Spirally Fluted Tube
Few studies exist that have investigated flow boiling in deep spirally fluted enhanced heat transfer tubing. This experiment seeks to determine the local heat transfer coefficient and pressure gradient for flow boiling of R-12 and R-134a 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 R-12, and from 1.4 to 2.5 with R-134a. In the convective regime there was a more substantial increase, with enhancements ranging from 3.5 to 7.6 with R-12, and from 3.3 to 7.1 with R-134a. R-134a had up to a 50% higher heat transfer coefficient than R-12. The pressure drop was found to be 6 to 20 times greater than a smooth tube with R-12, and 11 to 19 times greater with R-134a.
Heat Transfer and Pressure Drop Characteristics of Flow Boiling in a Horizontal Deep Spirally Fluted Tube
MacBain, Scott M. (author) / Bergles, Arthur E. (author) / Raina, Sunil (author)
HVAC&R Research ; 3 ; 65-80
1997-01-01
16 pages
Article (Journal)
Electronic Resource
Unknown
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