Re: Data Center Heat Recovery
Leakage current on package only appears if the CPU runs at more than 65°C. This happens very frequently in air cooled environment, when we see CPU at up to 90°C (package temperature). DLC and Immersion allow an inlet temperature between 35 and 45 (depending on technology and “side cooling” for hybrid cooling systems), and will allow heat recovery, without facing leakage current on package.
I think your message was to say that, to get water at 65°C (for reuse), it is better to get the water out of the IT at around 50°C, and use a heat pump. The heat pump with inlet at 45°C will have a COP of 4 (up to 6, in some cases) while the CPU has a COP of 1 (or even below 1 if you calculate it the same way you do for a heat pump).
BTW, looking at real cases, a heat pump is usually required to regulate the temperature entering the reuse system, if you want to inter-operate with standard building heating or hot water systems that are already in place. Cases that go direct from IT water to facility hot water (NREL, LRZ, etc.) look like ‘home-made’ with a lot of adaptations just not to use a heat pump. I agree that connecting the outlet to a heat pump will be the most efficient long-term investment.
De : main@OCP-All.groups.io <main@OCP-All.groups.io>
De la part de Steve Harrington via groups.io
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
5900 Sea Lion Place, suite 150 Carlsbad CA 92010
On 5/19/2020 12:10 PM, Kevin McCoin via groups.io wrote: