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Optimization of correlations for tube bundles during boiling heat transfer with hydrocarbons.

Number: pap. ID32

Author(s) : WANG Y., LUKE A., ESTIOT E.

Summary

The boiling heat transfer across horizontal tube bundles is calculated usually with empirical correlations, which are extrapolated from the results of heat transfer measurements on single tubes. Our results on single tubes for various hydrocarbons, e.g. n-pentane, are used to predict the boiling heat transfer for tube bundles and compared with the new results measured in a large-scale tube bundle typically used for industrial application. The comparison reveals that flooded shell and tube evaporators have been designed with pool boiling data for single tubes, which is inherently inaccurate due to the convective effects from rising vapour bubbles in tube bundles. It also reveals that the application of convection boiling models is still tentative and requires further investigation based on the phenomenal mechanisms. An improved correlation due to the in-depth analysis of the bubble movement during sliding up along the overheated heating surface should be developed. The bubble formation and movement is recorded using the high speed video technique and evaluated with a template-based method. By references to the results of the video evaluation, the convective effects particularly important in the low and moderate heat fluxes. Furthermore, this study presents a short overview on different calculation methods for the integral heat transfer coefficient in horizontal tube bundles and convective effects during boiling. It shows that the current correlations may be classified into four basic types. There are noticeable discrepancies among them and no one before now can be recommended as a general design tool.

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Pages: 8 p.

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Details

  • Original title: Optimization of correlations for tube bundles during boiling heat transfer with hydrocarbons.
  • Record ID : 30012283
  • Languages: English
  • Source: 11th IIR Gustav Lorentzen Conference on Natural Refrigerants (GL2014). Proceedings. Hangzhou, China, August 31-September 2, 2014.
  • Publication date: 2014/08/02

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