Liquid Cooling for Data Centers

CF-CDU15 Rack-Scale Overview

The Chilldyne Cool-Flo® System is a direct-to-chip liquid cooling system that delivers coolant under negative pressure in both directions. Chilldyne’s technologies were designed specifically to eliminate the risks associated with liquid cooling while keeping deployment and operating costs low. The Chilldyne system mitigates risk with its patented leak-proof design.


About The Rack-Scale System

Chilldyne’s Rack-Scale liquid cooling system offers all the well-known benefits of liquid cooling without the cost, complexity and risk. Coolant delivered to the servers and manifolds is under negative pressure on both the supply and return so coolant cannot leak out; only air can leak into the system. The Chilldyne Cooling Distribution Unit (CDU) can use cooling tower water at 15-30oC (59-86oF) to remove up to 15 kW of server heat. The CF-CDU15 is a packaged system with pre-installed software and web page based monitoring and controls . This provides flexibility in integration with your data center for a trial or a user laptop for demo. The software and user interface for the RSS is harmonized with Chilldyne’s Full-Scale System (FSS) for production data-center use. This allows users to familiarize themselves with the operation and control of the Full-Scale System before deploying it in a production environment.

Key Features
  • 8 lpm cooling flow at 5-40oC (41-104oF)
  • Monitors water temperature flow rate and heat transfer, fills, drains and test for leaks
  • Failure tolerant, negative pressure system
  • Data logging of key performance parameters
  • Web based software: control and monitor from anywhere.
  • Automatic drain and fill under remote control.
  • Enables liquid cooled product development.
Low Risk

The Cool-Flo System uses a proprietary,
negative pressure main pump
combined with standard heat sinks
modified for liquid cooling to provide a
leak-free system.

High Reliability

The Cool-Flo System pistonless
pump works with pneumatic
ejector technology. This type of
pump has very low maintenance
and is failure tolerant.

Cost Effective

The Cool-Flo system takes advantage
of the negative pressure to utilize
inexpensive hardware components,
leading to cost-effective


Software and Accessories

Allows for remote operation (fill, run, drain, purge, test…) via web page. Displays system state and error
messages, such as loss of facility cooling. Calculates heat removed, dew point, facility water flow rate.

Run Mode

Reports data on flow rate, pressure temperature, heat pumped, water quality etc.

Service Mode

Allows user to evacuate coolant from all the servers, Fill, Drain and conduct a vacuum test to test for any leaks in the system.


Dual Xeon Kit

Liquid and air cold plate/heat sink and no drip hot swap connector. Standard 90mm heat sink design

GPU Cold Plate

Custom Cold plate for 300 watt Fury X GPU, uses OEM VRM cooler

Dual Xeon Kit

Liquid and air cold plate/heat sink and no drip hot swap connector. Standard 90mm heat sink design


Innovative Technologies

  • Retains Air Cooling
    Utilizing standard finned heat sinks modified for liquid cooling, the Chilldyne system can retain the ability to air cool servers and can operate as a standard air-cooled system to minimize down-time.
  • Leak-Proof System
    Cool-Flo® uses negative pressure on both supply and return so if a leak occurs anywhere air will flow into the system instead of coolant leaking out.
  • Failure Tolerant
    The system will maintain cooling even with one server open to air. Leaks are a mainte-nance issue, they do not reduce uptime.
  • Increased Density
    With liquid cooling, the power density is only limited by the electricity that can be delivered to the chip. This means shorter connections between servers and higher speed data transfer.
  • Low Cost and Easy Installation
    The Chilldyne system has no hidden installation costs or delays. Plumbing is only required for the CDU while the racks and servers can be installed by data center technicians.
  • Reduced Setup Time
    The CDU automatically fills and drains the system, monitors the coolant and adds or drains coolant as needed. Air purging is automatic to reduce setup time and maintenance effort.
  • Automatic Coolant Evacuation
    The Cool-Flo No-Drip/Hot Swap Connector automatically evacuates coolant from a server when it is disconnected from a system The racks can also be drained automatically.
  • Low Cost, High Volume
    The system utilizes low cost plastic tubing and simple connections, minimizing cost and allowing data center technicians, not plumbers, to reconfigure racks.

Liquid Cooling Power Savings

Chilldyne’s Cool-Flo System is an efficient and low
cost liquid cooling system that reduces data center
power consumption 3 ways:

• 75-100% reduction in HVAC power
• 75% reduction in server fan power
• 5-10% reduction in CPU power

This example shows a legacy data center power
reduction of 45% with the Cool-Flo System. Any data
center can bring their Power Usage Efficiency (PUE)
down to 1.2 or less plus additional power savings at
the server.


Chilldyne CDU Specifications CF-CDU15


Dimensions: 8.75x21x32in (CDU) mounted near servers. 8.75x21x26in (Vacuum Pump) in rack or under floor.
Weight: 52 lbs (CDU) 45 lbs (Vacuum Pump)
Frame Details: Constructed out of PVC for maximum corrosion resistance. These units fit into a standard computer rack.
Panel Details: Removable top for full service access.
Power : 120-240 V 50/60 Hz
Cooling water: 3 gpm (12 lpm) for full power, 5 psi (35 KPa) DeltaP
Vacuum: 2 CFM @ 20 in Hg ( 30 lpm @ -70 KPA) can be provided by Chilldyne vacuum pump unit.


CDU Cooling Control:

  • The water temperature to the servers is maintained at a temperature above the dew point in the data center based on a temperature and humidity sensor included in the CDU
  • Tap water once through the CDU can be used for temporary testing in most locations, depending on local regulations. Facility Chilled water, standalone chillers , radiators can also be used.

Heat Exchanger:

  • The unit is equipped with a single, stainless steel brazed plate liquid/liquid heat exchanger. Facility cooling water flows in a second loop within the CDU through these heat exchangers.
  • The facility side of the HXs are connected using 3/4” diameter garden hose fittings.


  • The unit includes a microprocessor controller which provides a web page interface which can be operated with any computer equipped with an Ethernet connection.
  • The unit automatically controls the flow through the servers, tests the system for leaks, fills, drains and maintains coolant levels
  • The unit monitors and records the vacuum, pressure, temperature (pump and facility side), dew point, water levels, and coolant levels


  • Ambient conditions 41-104oF (5-40oC), 0-95%RH (non-condensing), 0-6000ft (0-2000m) elevation. Higher and lower temperature ranges are available via special order.


  • The CDU can be connected to a coolant reservoir, which contains coolant with anti corrosion and anti bacterial additives. The coolant reservoir level should be checked every 3 months.
  • The coolant should be drained and replaced annually.