1. Overview of Liquid Cooling Systems Peter Rumsey, Rumsey Engineers

2. Outline What is liquid cooling? Energy Benefits What is water side economizer Combined benefits

3. Why Liquid Cooling? Heat Capacity of this much air = Heat Capacity of this much water

4. Fans move energy less efficiently

5. Liquid Cooling Closer coupling between cooling source and server

6. Liquid Cooled Racks Racks with integral coils

9. Yesterday

10. Today

12. Comparison of Conventional Cooling to Liquid Cooling – 1,000 kW data center load Cooling Towers and Pumps ChillerChilled Water Pumps FansOtherTotal Power (kW) % SAVINGS Traditional System - 45 Deg F Chilled Water 7050050150n/a770N/A Liquid Cooled with Fans in the Rack - 55 Deg F Chilled Water 7042550100n/a64516% Liquid Cooled without fans in the rack - 55 Deg F Chilled Water 70425500n/a54529% Liquid Cooled directly couple with CPU - 70 to 80 deg F Chilled Water 700500Room A/C - 245 36553%

13. Free Cooling Use cooling towers and heat exchanger to produce chilled water Turn off chiller

15. Three – Well Suited For 24 hr Load

16. Put in series with chiller free cooling can improve reliability

17. Free Cooling

19. Comparison of Conventional Cooling to Liquid Cooling – 1,000 kW data center load With Free Cooling Cooling Towers and Pumps ChillerChilled Water Pumps FansOtherTotal Power % SAVINGS Traditional System - 45 Deg F Chilled Water 7050050150n/a770N/A Liquid Cooled with Fans in the Rack - 55 Deg F Chilled Water 7025550100n/a47538% Liquid Cooled without fans in the rack - 55 Deg F Chilled Water 70255500n/a37551% Liquid Cooled directly couple with CPU - 70 to 80 deg F Chilled Water 700500Room A/C - 150 27065%

20. Take Aways Liquid has greater heat removal capacity Pumps are more efficient than fans Coupling heat removal to the source eliminates mixing Commercially available liquid solutions are available Water side free cooling provides cooling with reduced chiller operation for much of the year in California

21. Thank You prumsey@rumseyengineers.com