Thursday, 30 July 2015

IBM Working on Absorption Cooling for Data Centres

IBM recently announced a new project aimed at using absorption cooling to keep data centres cool.  The project, known as 'THRIVE', aims to combine silica gel with some of the heat produced by data centre servers to cool those same servers through a process that could reduce the amount of power used for cooling purposes.  Although using heat to cool data centres seems counter-intuitive, the principal has proven effective on a small scale.

Absorption cooling uses heat to remove heat.  How does that work?  To understand the principle, it helps to first understand how vapour compression refrigeration works.

A traditional air-conditioning unit utilises a compressor, heat exchanger and gas or liquid refrigerant to remove heat from a given space.  The refrigerant is sent to a compressor as it enters the space that needs to be kept cool, causing that refrigerant to absorb heat from ambient air.  The refrigerant continues through tubing until it exits the refrigerated space, enters a heat exchanger and is forced to rapidly expand, thereby releasing all of the absorbed heat.  It then cycles through to the compressor and starts the process over again.

Vapour compression refrigeration requires electricity to power compressors and pumps.  You can imagine the power and cooling needs of the average data centre make this form of cooling an expensive proposition.  This is the very reason data centre designers are constantly looking for new ways to keep spaces cool.  Enter IBM and its absorption cooling process.

Absorption cooling involves no mechanical parts and, thereby, no electricity.  The process begins with a solid material, like silica gel, that absorbs the desired refrigerant in its natural state.  Heating the solid material releases the refrigerant, which is then free to absorb heat from ambient air.  Removing the heat source from the solid material causes it to reabsorb the refrigerant, thereby completing the cycle.

Some of the heat generated by the data centre server can be used to drive the system so that no external electricity is necessary.  The best part is that once you get the process started, the physics keep it going without much additional energy needed.

Long-Range Potential

IBM is most likely a long way from perfecting an absorption cooling method that would be viable for large-scale commercial purposes.  Unfortunately, they have to overcome some fundamental laws of physics in order to create a system that is self-sustaining over time.  However, they believe they are on the right track with the goals set for the THRIVE project.

IBM researchers claim that if their theories prove correct, these could lead to a reduction in data centre power consumption by as much as 65% by 2040.  At the same time, they believe they can reduce fossil fuel consumption for data centre cooling purposes by as much as 18%.  These are ambitious goals, to say the least.  Accomplishing them would put IBM at the forefront of new power and cooling systems that could make the data centres of tomorrow more eco-friendly.

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