Study of Hybrid Wet/Dry Cooling With Different Surface Morphology: Analyses on Pressure Drop and Thermal Performances

Abstract

This work conducts a multiphase multi-physics numerical study on this mixed mode cooling system, where evaporation of a liquid water film augments the convective cooling by evaporative heat and mass transfer. The mathematical framework consists of coupled mass, momentum, energy equation with species transport of air and evaporated water in the gas phase. Author’s prior works on perfectly flat surface predicted a minimum 500% increase of heat transfer coefficient in presence of a dual mode heat transfer. Current effort conducts a parametric study based on the different surface roughness structures over a broad range of Reynolds number condition. Array of circular, squared and triangular shaped grooves have been introduced along the surface exposed to the evaporating liquid. The cooling performances have been analyzed for different surface roughness structures and then compared against the flat film configuration. Furthermore, pressure drop across the liquid-gas interface has also been analyzed to predict the pumping power of the system. Model predicts that triangular shaped grooves exhibits a maximum ∼22% decrease in thermal resistance with a minimum pressure drop (∼5.5 times) across the interface. The square shaped surface morphology achieves 18% reduction in thermal resistance, with a penalty of pressure drop increase by a factor of ∼8. In comparison, circular grooves exhibit similar thermal performance but with a slightly a lower pressure drop (∼7 times). The numerical predictions have been compared with similar experimental findings and qualitative agreement was observed.

Experimental study of heat transfer in tube-type radiator of hybrid cooling tower

“…A hybrid cooling tower (HCT) refers to a combined system including features of heat and mass transfer of evaporative and dry cooling towers [7][8][9][10]. The key advantages of HCT:  Less number of expensive heat exchange equipment used in the dry part.…”

A Molecular Dynamics Study of Heat Transfer Enhancement during Phase Change from a Nanoengineered Solid Surface

“…Researchers have also found that a nanoengineered surface shows a significant enhancement in heat transfer as well as reduced thermal interface resistance [7][8][9]. While surface modification promotes mixing and boosts up thermal performance, it also introduces an Processes 2021, 9, 715 2 of 18 increased pressure drop across the modified surface [10,11]. Researchers are keen to understand the nanoscale behavior of thin layer boiling as it can help meet the high demand for electronic cooling in the manufacturing industry.…”