Liquid-to-Air Coolant Distribution Units Performance and Considerations for Server Rooms Upgrade With Conventional Air Conditioning

Abstract

As web-based AI applications are growing rapidly, server rooms face escalating computational demands, prompting enterprises to either upgrade their facilities or outsource to co-located sites. This growth strains conventional heating ventilation and air-conditioning (HVAC) systems, which struggle to handle the substantial thermal load, often resulting in hotspots. Liquid-to-air (L2A) coolant distribution units (CDUs) emerge as a solution, efficiently cooling servers by circulating liquid coolant through cooling loops (CLs) mounted on each server board. In this study, the performance of a 24-kW L2A CDU is evaluated across various scenarios, emphasizing cooling effect and stability. Experimental tests involve a rack with three thermal test vehicles (TTVs), monitoring both liquid coolant and air sides for analysis. Tests are conducted in a limited air-conditioned environment, resembling upgraded server rooms with conventional AC systems. The study also assesses the impact of high-power density cooling units on the server room environment, measuring noise, air velocity, and ambient temperature against ASHRAE standards for human comfort. Recommendations for optimal practices and potential system improvements are included in the research, addressing the growing need for efficient cooling solutions amidst escalating computational demands.