By tackling the liquid cooling issue from a vendor-neutral perspective, ASHRAE will likely boost the adoption of liquid cooling in the data center. SearchDataCenter.com caught up with Don Beaty of ASHRAE's Technical Committee TC 9.9 to talk about the upcoming publication. Beaty was traveling in Europe when we contacted him -- this is an excerpt of an email interview.
Give me the basics on the new book.
Don Beaty: The book will run 100-125 pages. It is currently being processed by ASHRAE for publishing and is scheduled to be available in November, but that could slip to December. The book will be available for online purchasing in hardcopy or electronic copy format. There are a number of us listed in the acknowledgements, but we are basically presenting the book as we have the previous books -- as the work of ASHRAE Technical Committee TC 9.9.
How is liquid cooling being used currently?
Beaty: There are various areas that liquid cooling can be applied. For example, all notebook computers are liquid cooled -- they use a heat pipe. This does not require a liquid connection to the computer, but rather the liquid is internal to the notebook. The cooling system is using the effectiveness of the change of state. The liquid in the sealed heat pipe changes phase or state from liquid to vapor and then back to liquid. The heat pipe is an example of liquid cooling within the electronic equipment and self-contained.
There is also liquid cooled electronic equipment that requires external liquid connections -- for example, in reduction or elimination of air cooling within the data center. In this case, liquid is delivered either near or directly to the rack or equipment (typically air is what is delivered to the rack or equipment). Once the liquid is within the vicinity of the rack or equipment, it is then used to cool air locally, which in turn cools the equipment.
Is liquid cooling a viable option for today's data center?
Beaty: There are definitely facilities and situations where liquid cooling is a viable option or the optimum choice. There are definitely facilities and situations where liquid cooling is not a good choice. Each application should be reviewed separately to understand the tradeoffs and make the right TCO [total cost of ownership] decision.
What are the benefits over air-based cooling?
Beaty: The heat carrying capacity of water is about 3,500 times more than for air. Water thermal conductivity is much greater than air.
These characteristics of water are helpful in meeting the challenge of cooling high-density loads. The advantages of liquid cooling increase as the load densities increase.
Earlier this year, you made a really interesting comment at a conference that stuck with me. You said vendors can't afford to fund liquid cooling and air-based cooling research, and production at the same time. For development of liquid cooling technologies IT pros are going to have to convince companies that they're willing to buy it. Has that happened?
Beaty: The equipment loads are continuing to increase and the liquid cooling interest is rising with the increased equipment loads. The amount of products and the amount of inquiries regarding liquid to the rack or near the rack has definitely risen.
Any emerging liquid cooling standards on the horizon?
Beaty: The book is a good start on standardizing nomenclature and architectures. The internal cooling strategies and design parameters of each IT manufacturer is specific to that manufacturer. The book discusses the equipment interface to the cooling source, which essentially is the basis of standardization.
ASHRAE has published other data center books, including Design Considerations for Datacom Equipment Centers.
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