National Science Foundation
Cooling Technologies Research Center
Purdue University - School of Mechanical Engineering logo

CTRC Breakthroughs

Surface and Interface Engineering

Surface Treatment for Boiling Heat Transfer Enhancement

Surface Treatment breakthroughs figure The present study proposes a free particle technique to provide the same active nucleation sites as for sintered particles, but with a deformable particle layer to reduce the vapor pressure drop during boiling (increases performance). A pool boiling test facility was constructed to allow high-speed visualization of boiling from a bed of free particles. Three free particle sizes were tested to investigate boiling characteristics and heat transfer enhancement over polished surface. The image shows the passive deformation of the free particle layer to release vapor bubble during pool boiling. A 32% reduction in surface superheat up to the same critical heat flux as measured for the polished surface is measured.

Acoustically Enhanced Heat Transfer

Acoustic Heat Transfer breakthroughs figure The aim of the project is the enhancement of heat transfer with an acoustic sound field with, ideally, a smaller pressure drop in comparison to other surface enhancements. This project involved experimental investigation of acoustically enhancing the heat transfer from a fluid flow to the solid wall of a plain tube and determining the influence of an acoustic field on the rate of heat transfer. A prototype test stand had been constructed in which air was the working fluid. The figure plots dimensionless heat transfer enhancement (Q/Q0) against the frequency at various sound levels (top) showing that heat transfer can be enhanced with an acoustic field by up to 30%. Differential pressure inside of the test section plotted against the frequency (below) shows that with a particular frequency, the differential pressure is negative.