Facebook is rolling out a new indirect cooling system, developed in collaboration with Nortek Air Solutions, which it claims is a first of its kind - and more efficient than existing indirect cooling systems.

According to Facebook, StatePoint Liquid Cooling (SPLC) can reduce data center water usage by more than 20 percent in hot and humid climates, and by almost 90 percent in cooler climates, when compared to alternative indirect cooling solutions. In development since 2015, the technology - which has been patented by Nortek - uses a liquid-to-air heat exchanger, which cools the water as it evaporates through a membrane separation layer.

This cold water is then used to cool the air inside the facility, with the membrane layer preventing cross-contamination between the water and air streams.

Fun with membranes

Inside a StatePoint Technology Unit
Inside a StatePoint Technology Unit – Nortek Air Solutions

“The system operates in one of three modes to optimize water and power consumption, depending on outside temperature and humidity levels,” Facebook thermal engineer Veerendra Mulay said in a blog post.

“When outside air temperatures are low, the SPLC’s most energy- and water-efficient mode uses that air to produce cold water. When outside air temperatures rise, the SPLC system operates in an adiabatic mode, in which the system engages the heat exchanger to cool the warm outside air before it goes into the recovery coil to produce cold water.

“In hot and humid weather, the SPLC operates in super-evaporative mode, where a pre-cooling coil cools outside air which is then used to produce cold water. In cooler climates, the SPLC system operates mostly in its most efficient mode; in hot and humid climates, it typically operates in super-evaporative mode.”

Facebook expects to operate SPLC mostly in economizer mode.

The SPLC unit features integrated control of supply water temperature and distribution pumping, which Facebook says simplifies the piping requirements for the data center. It can be connected to a number of cooling delivery systems, such as fan-coil walls, air handlers, in-row coolers, rear-door heat exchangers and direct-to-chip cooling.

Facebook uses direct evaporative cooling systems in most of its data centers, and says they require 50 percent less water than a typical data center, as long as the climate conditions permit this. “But the SPLC system will allow us to consider building data centers in locations we could not have considered before,” Mulay said.

Buddy Doll, president of Nortek, added: “It’s time for data centers to highly consider alternative technologies that will protect our environment. This is why we are thrilled to work with Facebook who has been a leader in developing innovative data centers around the world.”