1. OCP Cold Plate Work Session
Jessica Gullbrand
Cold Plate Work Stream Lead
Advanced Cooling Solutions

2. ACS Cold Plate Focus
Focus group working on ACS Cold Plate Requirements
Technology Cooling System (TCS) fluid loop
- Cooling loop from CDU through rack manifold and IT equipment and back
Provide information/education, classification, and minimal requirement for OCP
Authors:
- Jessica Gullbrand, Intel
- Nigel Gore, Iceotope
- Elizabeth Langer, CPC

3. ACS Cold Plate Requirements Focus
Technology Cooling System (TCS) Examples
In-Rack CDU
Row Level CDU
Virtual CDU
Use the Facility Cooling
Liquid in TCS loop
Figure by Intel, C. Winkel

4. ACS Cold Plate Definition
Hybrid Cooling – both liquid and air cooling
IT Equipment/Rack (with or without rear-door heat exchanger, RDHX)
Full Liquid Cooling – all heat is rejected to liquid
Rack/IT Equipment (with or without RDHX)

5. ACS Cold Plate Definition
Cold Plates – Heat exchangers or heat sinks with internal tubing or channels to allow cooling liquid to flow through
Coolant Distribution Unit (CDU) – Circulates the cooling liquid to the IT equipment and transfer the heat to the facility cooling liquid
Rack Manifold – Distributes cooling liquid within the rack
Quick Disconnect Couplings – Disconnects the IT equipment or its components from the TCS loop for serviceability

6. Cooling Liquid Considerations
Cooling Liquids Included (Single- and Two-Phase Liquids):
Water with additives
Glycol based liquids
Dielectric liquids
Refrigerants
Material compatibility required between wetted materials and cooling liquid
What cooling liquids are covered/considered in DCF?

7. Liquid Cooling Requirements
Pressure Safety Requirements
The liquid cooling loop, its ingredients, and connections must be tested to the highest pressure of the safety standards:
The IEC For EU and US, this standard is outgoing and is expected to be withdrawn on December 20, 2020 in favor of the IEC standard.
The IEC is the new safety standard requiring leak tests at 3x under normal operating pressure and 2x under abnormal and single fault conditions
ASME B31.3 “Process Piping” (2018) requires leak test at the 1.5x design pressure for interconnecting piping
What pressure requirements are being considered by DCF?
Standards valid on facility level? On TCS level?

8. Liquid Cooling Classifications
IT Equipment Classifications
Hybrid Basic: CPU/GPU cold plates
Hybrid Intermediate: CPU/GPU & DIMMs cold plates
Hybrid Advanced: CPU/GPU & DIMMs & Additional (specify) cold plates
Full Liquid: cold plates on nearly all components

9. Liquid Cooling Classifications
Liquid Rack Classifications
Hybrid Liquid Cooled Ready Rack without RDHX*
Hybrid Liquid Cooled Ready Rack with RDHX*
Full Liquid Rack Cooling without RDHX*
Full Liquid Rack Cooling with RDHX*
*RDHX = Read-Door Heat Exchanger

10. Performance Metric

11. Performance Metric PUE versus TUE for liquid cooling
PUE = Power usage effectiveness
TUE = Total PUE, “PUE” type metric
ITUE = PUE for the IT equipment

12. Performance Metric

13. Performance Metric

14. Performance Metric

15. Performance Metric

16. Performance Metric g i

17. Performance Metric

18. Performance Metric

19. Future Topics of Importance
Manifold Design
Connector Specification
Leakage Detection & Mitigation
Performance Metrics
Testing/Metrology/Requirements

20. Backup

21. ACS Cold Plate Purpose
Purpose: Generate an open specification and supporting documents focusing on standardization and definitions of liquid cooled solutions without preventing innovation
Note: Cold Plate work stream is focusing on liquid cooled solutions using cold plates

22. Liquid Cooling Requirements
Certification Markings
Each liquid cooled technology needs to comply with all certification regulations, which are valid for the geographic location where the liquid cooled system is used. Different regions have different requirements.
Examples:
UL and FCC markings in the US
CE certification in Europe

23. Cooling Liquid Considerations
Water with Additives
Water with Additives
Pros
Cons
Good heat transfer properties (high conductivity and specific heat)
Additives needed for reducing corrosion risk and bacterial growth
Ongoing regular maintenance

24. Cooling Liquid Considerations
Glycol Based Liquids
Glycol Based Liquids
Pros
Cons
>25% glycol no bacterial growth
Changes to viscosity => changes pump power conditions including power needed
Improved maintenance schedule
Lower conductivity and specific heat with increasing glycol level

25. Cooling Liquid Considerations
Dielectric Liquids
Dielectric Liquids
Pros
Cons
No short circuit of electronics during potential leaks
Adds liquid weight
Higher Global Warming Potential (GWP)
Higher cost
Limited supplier availability
Potential for flow instabilities and maldistribution in micro-channel cold plate using 2-phase

26. Cooling Liquid Considerations
Refrigerants
Refrigerants
Pros
Cons
Increase in thermal performance compared to single-phase
Environmental - Ozone Depletion Potential (ODP) and Global Warming Potential (GWP)
Potential for no and lower pumping power compared to single-phase
Potential loss of liquid under maintenance conditions
Specifically newer refrigerants can have lower GWP than dielectric 2-phase liquid
Higher operating pressure than single-phase
Can be inert: nontoxic, nonflammable, nonelectrically conductive
Potential for flow instabilities and maldistribution in micro-channel cold plate using 2-phase
Specialist knowledge required for commissioning, handling, and maintenance