Two-Phase Flow Heat Transfer

Higher cooling performances

Working principle

When undergoing phase change (from liquid to vapour or vice versa), fluids have the ability to exchange significant amounts of energy. This is mostly due to the fluid's latent heat and the flow’s high heat transfer coefficient, here illustrated for various types of flow. This makes two-phase cooling the best alternative for cooling of high heat flux applications.

Two-phase heat transfer coefficients increase with local heat flux, again providing a passive optimal hotspot cooling solution.

Refrigerants typically used in such cooling systems have great dielectric properties, increasing operational safety, and their Global Warming Potential has systematically decreased in the last few decades.

A graph showing the GWP for different refrigerants

Our mission is to work with clients and partners in the development and integration of disruptive, green and financially competitive cooling systems into the market.

Our solution? Passive two-phase cooling!

Passive two-phase cooling refers to the cooling of components using a working fluid that undergoes phase change and has self-sustained motion driven by the application/extraction of heat. We specialize in innovative technologies, including Pulsating Heat Pipes (PHP) and Loop Thermosyphon Systems (LTS).

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Why passive two-phase cooling ?

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No rotating parts to sustain working fluid motion
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No or reduced power consumption up to 90% for some applications
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High density heat dissipation (high efficiency of two-phase heat transfer)
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Increased temperature uniformity
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Reduced noise and vibrations (no rotation parts to sustain working fluid flow)
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Reduced maintenance and leakage
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Increased components lifetime (two-phase heat transfer happens isothermally, yielding excellent hot spot cooling and reduced thermal gradients)
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Reduced operating costs (lower or no electrical consumption, reduced maintenance compared to conventional technologies)

Suitable applications for passive two-phase cooling ?

From a few watts to megawatts, it can scale efficiently while maintaining low temperature levels (<90°C for most applications). Two-phase cooling is especially relevant for high heat-flux applications (>10W/cm2), where standard heat spreaders or air-cooled solutions reach their limits. Examples include CPUs in 1U and 2U servers, telecom, aerospace, automotive and power electronics.

A schematic representation of the heat flux
Heat fluxes higher than 10 W/cm².
Two-phase cooling offers the best trade-off between performance, integration and reliability !
Ease of design
Ease of integration
Maximum heat flux
Maintenance
Noise
Power consumption
Temperature uniformity
Thermal efficiency
Weight
Air cooling
Immersion liquid cooling
Pumped liquid cooling
Passive two-phase cooling
Pumped two-phase cooling
Two-phase cooling offers the best trade-off between performance, integration and reliability !
Ease of design
Ease of integration
Maximum heat flux
Maintenance
Noise
Power consumption
Temperature uniformity
Thermal efficiency
Weight
A
B
C
D
E
A
Air cooling
B
Immersion liquid cooling
C
Pumped liquid cooling
D
Passive two-phase cooling
E
Pumped two-phase cooling