Featured in the LIT (Ladies in Tech) Newsletter
Several new liquid cooling technologies are on the market, and even more manufacturers. This technology term deals with these cooling methods: D2C or direct-to-chip is one, and immersion is the other. We are going to discuss both. Both are considered closely coupled cooling methods that use liquid piped and moved via a CDU or coolant distribution unit (liquid mover). Now, let’s explain the jargon.
Think of it this way: suppose you heat a pot of water on the stove. The water absorbs the heat from the burner. In a data center, the burner is the computer chips, and the liquid is whatever we use to cool. When you move the pan from the stove to another location, you have rejected heat from the stove. Or at least as much as you can fit in the water in the pan.
Next, something will remove the heat from the water in the pan. It will either evaporate naturally (heat rises). Or we need to transfer it to something else that will absorb the heat from the water (chiller or some other means). If you move it to the sink, dump it, and change it out with cool water, you can return to the stove and absorb more heat from the burner.
In the above example, you are the CDU. But you get the idea. Basically, you are providing liquid pathways for heat. If you leave the burner on without a pot of water, your kitchen becomes hot. Data centers do the same. The difference is that your home won’t shut off due to high heat, but computing equipment will.
Why liquid, you ask? We can answer this with a short precursor to data center cooling. The biggest thing to note is that we aren’t actually cooling. We are, in fact, removing heat -aka- heat rejection. The result is more excellent fluid. Computers generate heat. We remove that heat to cool the facility. We can reject the heat with water or air. Water is 3500% more efficient at absorbing heat for rejection. Other refrigerant liquids have greater or similar absorption properties and can absorb more heat without boiling.
To further increase efficiencies, the closer the liquid is to the heat source (the chip,) the more efficiently it absorbs heat. Cooling attached to or near the heat source is referred to as closely coupled cooling. In the above example with the stove, if you place the pot 3” above the burner, it will take longer to absorb the heat, and there will be heat loss between the burner and the bottom of the pan. Sitting directly on the burner (closely coupled) increases the heat absorption rate and removes accidental heat loss.
Direct 2 Chip pipes the coolant through the server via hardware and tubes that attach directly to the processing chip. Clever name, huh!?! Immersion cooling is similar, but the entire server is submerged/immersed in a non-dielectric (won’t conduct electricity) liquid (another descriptive name). The fluid moves through the tank to a CDU and then to a chiller or other external heat rejection apparatus. The result is a cooler computer and computer room.
In both examples, we have rejected the heat away from the servers. The frequency in which this happens is called flux. As computers continue to generate heat, we must continue to reject it.
Want to know about other technology terms? Email CarrieG@strategitcom.com
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