Session: 02-05 Hardware Cooling I

Paper Number: 97421

97421 - Determination of the Thermal Performance Limits for Single Phase Liquid Cooling Using an Improved Effectiveness-NTU Cold Plate Model 

Liquid-cooled cold plates mounted on the package are at the heart of pumped liquid cooling systems.  In this paper, we report on combined experimental, analytical, and computational efforts (i.) to characterize and model the thermal performance of advanced cold plates using water and water-glycol mixtures as coolants, and (ii.) to establish the performance limits of families of such cold plates by understanding, modeling, and generalizing their behavior.  A novel effectiveness-NTU formulation  is introduced that models the fin array as a secondary “pseudo-fluid” such that accurate cross-flow effectiveness models can be utilized to model cold plates with various flow configurations including side-in/side-out and impinging split-flow top-in/side-out flow paths.  Experimental measurements and conjugate CFD simulations were made on a variety of copper cold plates with fin and channel features of order 100 um with both distilled water and water-propylene glycol (PG) mixtures as coolants.  We show that for a fixed fin geometry, the best thermal performance, regardless of the pressure drop, is achieved when the flow rate is high enough to approach the convective limit which unfortunately also occurs at low effectiveness. For the cold plates evaluated in this study, this limited heat dissipation to 1.5 kW for the allowable TDP.  However, for a fixed pressure drop, the optimal cold plate should be designed to meet its TDP at the highest possible effectiveness, normally achieved for NTU > 5.  This requires that the surface area and heat transfer coefficient be increased by optimizing the geometry to maximize NTU for a targeted TDP.

Presenting Author: Alfonso Ortega Villanova University