Simultaneous heat and mass transfer to air from a compact heat exchanger with water spray precooling and surface deluge cooling

Feini Zhang, Jessica Bock, Anthony M. Jacobi, Hailing Wu

Research output: Contribution to journalArticlepeer-review

Abstract

Various methods are available to enhance heat exchanger performance with evaporative cooling. In this study, evaporative mist precooling, deluge cooling, and combined cooling schemes are examined experimentally and compared to model predictions. A flexible model of a compact, finned-tube heat exchanger with a wetted surface is developed by applying the governing conservation and rate equations and invoking the heat and mass transfer analogy. The model is applicable for dry, partially wet, or fully wet surface conditions and capable of predicting local heat/mass transfer, wetness condition, and pressure drop of the heat exchanger. Experimental data are obtained from wind tunnel experiments using a louver-fin flat-tube heat exchanger with single-phase tube-side flow. Total capacity, pressure drop, and water drainage behavior under various water usage rates and air face velocities are analyzed and compared to data for dry-surface conditions. A heat exchanger partitioning method for evaporative cooling is introduced to study partially wet surface conditions, as part of a consistent and general method for interpreting wet-surface performance data. The heat exchanger is partitioned into dry and wet portions by introducing a wet surface factor. For the wet part, the enthalpy potential method is used to determine the air-side sensible heat transfer coefficient. Thermal and hydraulic performance is compared to empirical correlations. Total capacity predictions from the model agree with the experimental results with an average deviation of 12.6%. The model is also exercised for four water augmentation schemes; results support operating under a combined mist precooling and deluge cooling scheme.

Original languageEnglish (US)
Pages (from-to)528-540
Number of pages13
JournalApplied Thermal Engineering
Volume63
Issue number2
DOIs
StatePublished - Feb 22 2014

Keywords

  • Deluge cooling
  • Heat and mass transfer
  • Louver-fin heat exchanger
  • Modeling
  • Precooling
  • Spray cooling

ASJC Scopus subject areas

  • Energy Engineering and Power Technology
  • Industrial and Manufacturing Engineering

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