ku:l SISTEM - Frequently asked questions

How does Iceotope liquid cooling work?

  • Iceotope liquid cooling uses two pumped circuits,(A & B) de-coupled by a plate heat exchanger.
  • The first circuit ‘A’ consists of a dielectric fluid that immerses and harvests the heat from every component on the heat-generating electronics and circulates, continuously, within a sealed chassis.
  • The dielectric fluid is pumped through a plate heat exchanger inside the chassis, where it transfers its heat to a secondary cooling circuit ‘B’.
  • The dielectric fluid and the cooling water do not come into contact with each other inside the heat exchanger, but heat transfers easily from one to the other.
  • Cooled fluid is then delivered to patented Iceotope coolant-retaining heatsinks on the hottest parts of the electronics via a manifold and the cycle repeats.

What are the main benefits of an Iceotope system?

  • Up to 40% reduction in Total Cost of Ownership
  • 38% reduction in Opex
  • 25% reduction in Capex
  • 1.03 Power Usage Effectiveness
  • 50% to 70% reduction in Floor space
  • 70% - 80% reduction in Energy Consumption
  • 30% Improvement in Memory Bandwidth
  • No requirement for air handling
  • Improvements in reliability
  • Improvements in performance
  • Compatible with Standard IT Hardware
  • Resilient and Silent: Deployable in any environment

Do you have to treat the servers with a special coating?

No. Coating of the electronics is not required.

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How big are your chassis?

Each chassis is 1U high and will fit into a standard 19” cabinet.

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How big is your cabinet?

All Iceotope equipment, including cabling at the front and cooling pipework at the rear, can be comfortably housed within a standard 19” cabinet (600mm wide x 1200mm deep).

How do you achieve the 50% - 70% reduction in floor space?

As the Iceotope system does not use fans for cooling, the data hall does not need the air-handling equipment and hot-aisle/cold-aisle containment. Aisles can be narrower and Iceotope cabinets can be located back-to-back. Servers can be loaded more densely into each cabinet.

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Are your chassis hot-swappable?

Yes, each chassis is hot-swappable, sliding into a rack-mounted rail kit that provides power and secondary-coolant connections at the rear of the chassis.

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How do you feed secondary-coolant into the chassis heat exchangers?

Each chassis connects to a vertical manifold mounted in the rear of the cabinet using blind-mate, double-shutoff connectors.

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Is there a risk of water drips from the connectors?

No, the connectors are flat-faced and each half has a valve so there is no space for a drip to form. Additionally, the water connectors and manifolds are to the side of the power connectors, so there is no risk

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How many chassis are fed by a manifold?

Each manifold will feed up to 12 1U chassis.

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How many chassis can I fit in a 42U cabinet?

Up to 36 chassis can fit in a 42U cabinet.

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How are the manifolds connected?

A distribution manifold, at the top of the cabinet, takes the secondary-cooling circuit(s) and feeds the coolant to up-to three chassis-level manifolds. An aggregating-manifold at the bottom of the cabinet then feeds the heated coolant back into the secondary-cooling circuit.

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Can I have redundant cooling circuits?

Yes, the cabinet level manifolds can accommodate ‘A’ and ‘B’ cooling circuits.

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Can I feed into the manifolds from above or below the cabinet?

Yes, the cabinet can be configured to accommodate secondary-cooling feeds from either above or below the cabinet.

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What pressure can the cabinet accept for the secondary-cooling circuit?

Heat exchangers in the chassis are rated up to 10bar.

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Is your system patented?

Yes, Iceotope has an ever-expanding portfolio of patents.

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Do you use phase-change?

No, we do not need to use phase change. Our dielectric fluid does not boil, as its boiling point is above the temperatures generated by the electronics. 

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Does the dielectric fluid have to be filtered in the system?

No, as this is a closed system, filtering is not required.

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Does the dielectric liquid dissolve flux residues from the PCB?

No, the coolant is not a solvent and will not dissolve flux residues. 

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Does the dielectric fluid decompose over time?

Our dielectric fluids are stable in thermal conditions above 300ºC. In the presence of oxygen the continuous use temperature of these fluids is somewhat lowered to 290ºC. Up to these temperatures, the decomposition of the fluids is negligible.

Our dielectric fluids have boiling points ranging from 55ºC to 270ºC and a typical operating range from – 70ºC to 270ºC.

They are high performance, inert fluids characterized by:

  • High thermal stability (up to + 290ºC)
  • The highest boiling point among fluorinated fluids (up to + 270ºC)
  • Very good dielectric strength and volume resistivity properties
  • Excellent chemical inertness
  • Good compatibility with metals, plastics, and elastomers
  • No flash or fire point, no auto-ignition point
  • NSF approved

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How does the fluid get into the chassis?

A measured volume of fluid is dispensed into the chassis on-site using a proprietary, sealed, pump.

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How do I service a server?

As the fluid creates a protective environment, the requirement for servicing is greatly reduced but should you be required to upgrade a component the process is very similar to that in an air-cooled chassis. The fluid is first removed from the chassis using the proprietary pump and then the lid is removed. 

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Can the fluid be removed from the chassis while it is still in the cabinet?

Yes, the fluid can be removed from the chassis while it is still supported in the cabinet, if required.

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How long does the fluid last?

The fluid has a useful life of 20 – 25 years. It can be filtered and reused if required.

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How much fluid is there in each chassis?

The volume of coolant in the chassis is dependent on the IT configuration of the device. The Iceotope system uses as little fluid as possible by carefully distributing within the chassis, proportionate to the cooling duty of individual components.

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How heavy is a 1U chassis?

The weight of a 1U chassis is dependent on its configuration but a typical device will weigh around 19kg.

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How heavy is a full cabinet?

A fully loaded, 42U cabinet will weigh around 955kg.

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What is the floor loading of a 42U cabinet?

With a footprint of 0.6m x 1.2m, a fully-loaded 42U cabinet mounted on a distribution plate would exert a force of 13kN/m2 (within the footprint of the cabinet)

If the service area for a cabinet is considered as part of the floor loading, the loading is 7.8kN/m2

Why is liquid so much better than air at cooling?

This is because water has a much higher specific heat capacity, density and thermal conductivity than air. This allows water to absorb more heat than air and transmit it over greater distances with much less volumetric flow and reduced temperature difference.

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So do you put your servers in water or oil?

Neither – we use a specially engineered dielectric fluid to harvest the heat from the hot electronics.

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What does dielectric mean?

A dielectric fluid is one which does not conduct electricity.

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Do you pump your dielectric fluid around the building?

No, the dielectric fluid stays within the sealed server chassis.

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Doesn’t the fluid affect the performance of the servers?

Yes, in a good way.  The fluid creates a protective environment for the servers, allowing them to perform better and last longer.

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Do you still need to use any fans for cooling?

No, the Iceotope system is completely fanless.

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Is there a risk of water coming into contact with the electronics?

No, the water-based secondary cooling circuit only flows through the plate heat exchanger to pick up the heat from the dielectric fluid.

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What are the typical temperatures inside the chassis?

Temp of secondary circuit into the heat exchanger = up to 45ºC (conforms to ASHRAE W4)

Dielectric fluid = up to 70ºC

Max operating temp of the processors = typically up to 85ºC (dependent on processor and vendor guidelines)

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How do you monitor temperatures inside the chassis?

We read IPMI data from the motherboard and from temperature sensors on the heat exchanger.

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What is the flow rate of the dielectric fluid?

Typically 1Ltr/min/processor + 1Ltr/min for the PSU, so 5Ltr/min overall.

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Can the pumps be controlled so that they pump in relation to the heat load?

We have, under development, pumps that can be PWM controlled from the fan header.

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What temperature does the secondary-cooling circuit need to be?

Secondary-coolant can be up to 45ºC into the cabinet. This means that the secondary coolant does not need to be chilled.

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What is the temperature delta (approach temperature) in the secondary-cooling circuit?

5ºC.

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Why do you design for a 5ºC delta?

Having a low temperature rise across the heat exchanger means we get a bigger temperature difference between the dielectric fluid and secondary cooling circuit, which promotes heat exchange. 

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What would you need to do to allow for a 10ºC delta? 

Reduce flow rate of the facility coolant, and compensate by retuning the server thermal and hydraulic operating point.

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We currently design for air cooling, working to deliver air temp of 18 - 27ºC into thechassis. How does this compare with 45ºC water into the chassis?

ASHRAE (American Society of Heating, Refrigeration and Air-Conditioning Engineers) have published guidelines for both air-cooling and liquid-cooling of IT equipment in Data Centres. Setting a maximum allowable air input to the chassis is to ensure that the processors run as efficiently as possible and do not overheat. As air cooling is a lot less efficient than liquid cooling, the air-input temperatures need to be considerably lower than liquid-input temperatures for liquid cooling. We can achieve the same or better levels of cooling using 45ºC liquid than with 27ºC air. 

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How do you reject the heat?

Due to the high output temperature of the Iceotope system, the heat generated can either be used for heating or can be rejected to ambient with a dry cooler.

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What is a dry cooler?

A dry cooler is a simple cooling unit that comprises a pump, radiator fan and thermostat.

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How much water does a dry cooler consume?

A dry cooler does not consume water; it recirculates water in a closed loop.

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What is the flowrate of the secondary-cooling circuit?

Flowrate is typically between 1 – 1.5Ltrs/min/server chassis (dependent on cooling duty and temperature of the secondary-cooling circuit).

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Is the secondary-cooling circuit just water?

The secondary-cooling circuit is a mix of water and up to 30% glycol antifreeze (with anti-fungal and anti-corrosion additives).

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What is the maximum cooling duty of a 1U chassis?

Each chassis can cool around 1.2kW of IT, dependent on flow rate and input temperature of the secondary-cooling circuit.

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Can we configure an Iceotope server with different IT?

Yes, the cooling system is flexible to accommodate different IT configurations.

Our patented IO PCBs allow the chassis to be configured to provide IO ports that are appropriate to the IT.

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Can we have redundant power?

Yes, the chassis could be configured to have two power feeds.

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What voltage is fed into the chassis?

A standard chassis takes 240V AC power from rack-mounted PDU(s).

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So do you also cool the power supply?

Yes, the power supply is liquid-cooled within the chassis.

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Do you have to modify the servers?

No, we can take standard, off-the-shelf servers and cool them in our system.