Liquid Cooling for Data Centers


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 Cooling Distribution Unit

The Chilldyne Cooling Distribution Unit (CDU) is a negative pressure system that uses liquid to cool up to 300kW of server heat. The Cooling Distribution Unit (CDU) can use cooling tower water at 1-55oC (34-131oF) to remove up to 300 kW of server heat (10oC rise). Its innovative design and energy efficiency allow for effective cooling of servers in high density applications.

Key Features
  • Pumps liquid with up to 10 lpm air leak with no reduction in performance.
  • Touchscreen Controls
  • Data logging of key performance parameters
  • Remote monitoring via webpage or SNMP
  • 4-6 cooling loops for easy hose routing
  • 300 lpm cooling flow at .5 bar
  • Monitors water temperature and quality, fills, drains, and tests for leaks
  • Measures heat removed and facility water flow
  • Automatic control of anti-corrosion fluid
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


CDU Components

1. Pump Chamber
The Chamber is where coolant is stored, supplied to the servers and received from the servers. The system cycles through the main and auxiliary chambers allowing for a steady flow.

2. Heat Exchanger (2x)
Transfers the heat created by the servers to the cooling tower or chiller. The HX are connected in series to minimize the processor temperature on hot humid days with warm cooling tower or dry cooler water.

3. Liquid Ring Pump (LRP)
LRP uses water as a seal to provide the required vacuum necessary to propel the coolant. The water seal does not wear out. Redundant pumps optional.

4. Microprocessor Control
The temperature in the fluid reservoir is controlled to maintain the coolant temperature above the dew point in the data center.

5. Water Quality Control
The water quality is monitored and controlled to maintain corrosion and bacterial protection. Automatic fill, drain, air purge and leak test are included and coolant
additive is stored onboard.

6. Coolant Handling Manifold
Standard 4-6 cooling loops exiting bottom of CDU. Optional single feed coolant supply for rear door HX applications at either bottom or top.


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-CDU300



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.