Liquid immersion cooling is the reduction of heat in hardware through submersion in a dielectric liquid that is thermally conductive.
One of the simplest examples of liquid immersion cooling is taking a standard air-cooled computer's hardware and submerging it in mineral oil. Mineral, oil being nonconductive and noncapacitive, poses no threat to the electronics. Computer enthusiasts sometimes use this method employing standard aquariums to hold the hardware. The fans continue to spin, circulating the oil over the heat sinks at a lower speed but with a more efficient fluid medium for cooling than air. This cools the components, as the oil first absorbs the heat, then benefits from evaporative cooling. However, that method cannot deal with high heat loads and needs occasional replenishment of the oil.
More sophisticated methods of immersion cooling are used in showpiece computers, mainframes and datacenters. These systems still often harness evaporative cooling and submerge the parts but they are often a closed system, more like a hybrid between traditional liquid cooling, complete with pumps and external radiators, and immersion cooling. Their liquid is most commonly an engineered dielectric fluid with a lower boiling point than water. The liquid evaporates, condenses and drips back to the purpose-designed tank. This cycle reduces the cost in fluid, which is often proprietary and expensive.
Liquid immersion uses up to 99 percent less electricity than traditional data center cooling with chillers, heat pump and HVAC. The greater cooling at less cost also makes greater system density feasible. Many immersion cooling set ups are complex. However, simpler -- yet very effective -- open bath systems often yield the lowest operational cost. Other benefits include nearly silent operation and less dust because of the reduction in required airflow.
Water cooling can limit the flexibility of data center design because systems connected to plumbing cannot be easily rearranged. The combination of electronic systems and water also complicates disaster recovery planning (DRP). Administrators need to know in advance how they will deal with potential problems, such as rust or leakage. Immersion cooling with dielectric liquid eases many of these concerns and the common fear of combining electrical systems and water.
The coolant can be creatively used to transport the heat where it is useful, leading to effective savings on heat as well. Most data center immersion cooling solutions are expensive to implement. However, because electricity used in cooling is one of the largest operational costs, the initial outlay for immersion cooling is typically offset quickly by power savings.
See a demonstration of liquid immersion cooling: