Consulting-Specifying Engineer, Sept. 21, 2016, by Saahil Tumber.
http://www.csemag.com/single-article/designing-with-liquid-immersion-cooling-systems/50ef4dcd4e7dee72b8d45e1fa4608abb.html

"Liquid cooling refers to a scenario where liquid (or coolant) must be supplied to the ITE. An IT cabinet is considered to be liquid-cooled if liquid, such as water, dielectric fluid, mineral oil, or refrigerant, is circulated to and from the cabinet or cabinet-mounted equipment for cooling. Several configurations are possible, depending on the boundary being considered (i.e., external or internal to the cabinet). For the same heat-transfer rate, the flow rate requirement for a liquid and the energy consumed by the pump are typically much lower than the flow rate requirement for air and the energy consumed by the fan system. This is primarily because the specific volume of a liquid is significantly lower than that of air."