Aluminum Micro-Channel Coils for Door HX Solutions

Author: Philip Waverik, VP Enterprise, Boyd; Shankar, Danos Collection: 2023 Global Summit - Cooling Environments

Summary

This presentation evaluates aluminum microchannel (ALMC) heat exchangers as a challenger to the incumbent copper tube-and-fin (T&F) construction for rear door heat exchangers (RDHx) in data centers. The work is a multi-party OCP collaboration within the ACS Door HX track. The core engineering question: can microchannel technology handle more cooling power with less weight and less fan power than tube-and-fin, given the known scaling limitations of T&F at higher rack densities?

The analysis compared a 30 kW ORv3-spec RDHx in both technologies at 3500 CFM airflow (the ORv3 baseline). Key result: at equivalent cooling capacity, aluminum microchannel delivers 59% lower air-side pressure drop, 78% lower unfilled weight (21.7 kg vs ~98 kg), 73% lower filled weight with 25% propylene glycol (~30 kg vs ~113 kg), and 45% lower internal volume (8.2 L vs ~15 L). The performance (thermal capacity, Q/ITD) stays within ±7% of tube-and-fin across all tested airflow rates and fluid flow rates. The one penalty: water-side pressure drop increases 59% (33 kPa vs 22 kPa).

The primary remaining challenge is materials compatibility in the technical water loop (i.e., combined cold plate + RDHx loops), where microchannel's small channel dimensions create corrosion and blockage concerns when mixed with copper cold plates. The facility water side (glycol loop without cold plates) has been demonstrated without issues in HVAC applications for decades.