Data Center Heat Recovery [EXT]

Don Mitchell

Steve – some great points.  Wish I had the data to help understand them better.


Finding reliable, current data on CPU temperature vs performance is a challenge. 

  • Air cooled IT vs liquid cooled IT – extremely different in heat transfer methodologies and temperature stability.   60C with air cooled chips will be a different study than 60C liquid cooled chips
  • Age of study – many studies date back to 2014 – few industries have changed more in 7 years than IT chips
  • Applications
    • many studies target gamers, miners….need for speed with minimal interest in efficiency. 
    • Edge vs Hyperscale – Look at Cloud & Heat, CoolDC.  While San Diego may not benefit from large sources of waste heat, smaller liquid cooled “Edge” applications may be practical, especially at higher temperatures.
  • Heat reuse form factor – most applications for heat reuse (besides hot house and agriculture) require liquid transportation of heat.  So 35C air becomes 30C liquid in Stockholm before it goes into heatpumps.  45F-60F liquid is a resource in most of the world – what is the true cost of that resource


Request – Would greatly appreciate any links to studies that are less than 2 years old, looking at liquid cooled chip performance. 

Laws of physics and heat transfer don’t change.  “Moores Law” and chip design do change.


Finally, Edge vs Hyperscale


Kind Regards & Keep Safe


Don Mitchell
Data Center Division Manager



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From: <> On Behalf Of Steve Harrington
Sent: Tuesday, May 19, 2020 2:46 PM
Subject: Re: [OCP-All] Data Center Heat Recovery [EXT]


The NREL data center is very efficient. However, when looking at heat recovery, you have to balance the extra power required at higher CPU temperature with the cost of efficient heat pumps. (a one to one comparison of watts of heat to watts of computer power is not appropriate) A hotter running processor may require 5% more power and a typical heat pump has a COP of 4.

This means that if you run your 100 watt processor hotter so it uses 105 watts to get usable heat, and the heat your are replacing requires 25 watts of power to produce 100 watts of heat, the 20 watt power savings for a 100 watts of heat may not justify the expense of hooking the computer to the heating system.

Also, once you hook up a heat source that you can't control to a heating system, you need to have a backup source of heat.

I don't think it makes sense for San Diego, but it might for a place where heat is expensive and the computers are running at full load all of the time.


Steve Harrington, Ph.D

Chilldyne, Inc | Founder & CTO | 760.476.3419 x510 | 760.994.5544 Cell

5900 Sea Lion Place, suite 150 Carlsbad CA 92010



On 5/19/2020 12:10 PM, Kevin McCoin via wrote:


NREL has done some really awesome stuff in this space and are currently operating at a 1.025 PUE.  Contact for this facility is Otto VanGeet:


Here’s a live dashboard that includes a depiction of their recovery approach:




Kevin L. McCoin

Distinguished Architect, Systems Engineering

Walmart Technology

Enterprise Critical Infrastructure Services
Phone: 479-277-2135  fax: 479-277-4244




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From: <> On Behalf Of Andrew Witteck
Sent: Tuesday, May 19, 2020 1:31 PM
Subject: EXT: Re: [OCP-All] Data Center Heat Recovery


Thank you Rolf,

This is very much appreciated.


Andrew Witteck | Specialty Markets Manager

Armstrong International

o (772) 213-9541 ext 4025

c  (772) 473-3055 


From: <> On Behalf Of rolf.brink@...
Sent: Tuesday, May 19, 2020 2:29 PM
Subject: Re: [OCP-All] Data Center Heat Recovery


Hi Andrew,


Yes, this is currently a topic in the ACS Harmonization project. Best bet is to get in touch with the DCF group. ACS and DCF are working together on topics like this. I will put you in touch directly as well.



Rolf Brink

ACS Immersion


From: <> On Behalf Of Andrew Witteck
Sent: Tuesday, 19 May 2020 20:14
Subject: [OCP-All] Data Center Heat Recovery



Hesham, I am not aware of cellular in data centers. I am sorry.

I am interested to find out if there is any work in OCP projects that is related to using Air-cooled data center or liquid cooled data center hall expelled heat for thermal utilities in surrounding buildings? Also if there is any direct/indirect evaporative media work being done as well.





From: <> On Behalf Of Hesham
Sent: Saturday, May 16, 2020 1:41 AM
Subject: [OCP-All] Cellular Data Center



I am interested to find out if there is any work in OCP projects that is related to using Celluar in the Data Center.




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