TY - JOUR
T1 - Simultaneous heat and mass transfer to air from a compact heat exchanger with water spray precooling and surface deluge cooling
AU - Zhang, Feini
AU - Bock, Jessica
AU - Jacobi, Anthony M.
AU - Wu, Hailing
N1 - Funding Information:
This material is based upon work supported by the Department of Energy [Geothermal Technologies Program] under award DE-EE0002738 [Optimization of Hybrid-water/air-cooled Condenser in an Enhanced Turbine Geothermal ORC System] to the United Technologies Research Center (PI: Dr. Hailing Wu).
PY - 2014/2/22
Y1 - 2014/2/22
N2 - 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.
AB - 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.
KW - Deluge cooling
KW - Heat and mass transfer
KW - Louver-fin heat exchanger
KW - Modeling
KW - Precooling
KW - Spray cooling
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U2 - 10.1016/j.applthermaleng.2013.11.046
DO - 10.1016/j.applthermaleng.2013.11.046
M3 - Article
AN - SCOPUS:84892437523
SN - 1359-4311
VL - 63
SP - 528
EP - 540
JO - Applied Thermal Engineering
JF - Applied Thermal Engineering
IS - 2
ER -