Performance of a tube-in-tube CO 2 gas cooler

Pei Yu Yu, Kai Hsiang Lin, Wei Keng Lin, Chi-Chuan Wang*

*Corresponding author for this work

Research output: Contribution to journalArticle

16 Scopus citations

Abstract

In this study, a tube-in-tube heat exchanger model applicable to supercritical CO 2 and water was developed. The developed model is first validated with some existing measurements. Normally, the variation of the heat transfer rate for a constant-property working fluid shows a monotonic decrease from the inlet of minimum heat capacity flow rate (C min). By contrast, the CO 2 may present a local minimum and a local maximum along the length of the heat exchanger, provided CO 2 passes through the pseudo-critical temperature, and this phenomenon becomes more and more pronounced when the pressure is close to the critical pressure. In contrast, it is possible for a local maximum heat transfer rate to occur near the inlet of C min even when the CO 2 does not pass through the pseudo-critical point. This happens when C min is on the water side and the property variation of CO 2 is taken into account. The calculation also shows that the effect of the inlet pressure on the variation of the CO 2 temperature is not as apparent as the effect of the inlet pressure on the heat transfer rate, even when there is a significant change in the overall heat transfer coefficient, implying that the heat transfer characteristics of CO 2 near the pseudo-critical region is similar to normal refrigerants, which show an invariant temperature at the condensation point. Hence, it would be beneficial to extend the influence of the pseudo-critical region when taking the heat transfer augmentation into consideration.

Original languageEnglish
Pages (from-to)2033-2038
Number of pages6
JournalInternational Journal of Refrigeration
Volume35
Issue number7
DOIs
StatePublished - 1 Nov 2012

Keywords

  • Carbon dioxide
  • Gas cooler
  • Heat exchanger
  • Pseudo-critical
  • Supercritical

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