Servers don’t sweat: Raise your chilled-water temp
In this podcast, Uptime Institute and ComputerSite Engineering Inc. guru Pitt Turner explains the difference between sensible and latent cooling in the data center. Latent cooling in the data center results in wasted energy. Turner outlines how to avoid spending more energy and money to cool servers than is necessary in this podcast from the Uptime Institute Data Center Design Charrette.
Posted: November 2nd, 2007 under Data center power efficiency, Data center cooling, Green data center.
Turn up the chilled water temp. Yes, “in theory” this is a great way to save latent heat energy from being removed from the data center. Unfortunately this should be done during data center design. Decreasing the latent heat removed in most cases reduces the capacity of the AHU /CRAC units by as much as 30%.
For example you have a 1000 ton active data center, it has n+3 on AHU / CRAC units (3-50 ton units). By rasing your Chiller Water Temp from 40 to 50 degrees you would need 30% more coil surface area or CRACs. You would need an additional 6-10 CRAC units to make up the tonnage difference. (CRAC tonnage is variable based on the difference between the returning air temp and the coil temp.)
I hope you now see the conundrum. To save the removal of the latent heat you need alot more space for CRAC’s and you also now have to add an additional 90HP in active motors for the AHU units.
Remember nothing is free in cooling you can only minimise the losses. Core 4 provides a 68% total energy reduction for maintaining the data center environment by reducing the energy draw from compressors, motors, latent heat, fans, well everything…
Comment by Rick Cockrell — December 1, 2007 @ 7:46 pm