Helium — perfect gas at high temperatures, pressures

Sep 2

Enerin uses the closed loop reverse Stirling system for its machines. Its unique design and advanced sealing technology makes it particularly well-suited for adaptation to reversible operation as a heat engine and for heat pumping in the forward mode.

Our heat pumps use Helium (R704)—He in the periodic table of elements—as the working fluid for their best overall performance. Nitrogen and Hydrogen can also be used as future-proof alternatives because the availability of Helium may decline with natural gas extraction.

He is an inert natural, safe refrigerant, which means that it is non-flammable, non-explosive and non-toxic, with zero Ozone Depletion Potential and Global Warming Potential.

Low molecular weight — High speed of sound

Stirling machines operate with a closed gas volume oscillating between hot and cold regions.
The faster the gas can transfer pressure waves and heat, the more efficient the process.
Helium has a very low molecular weight (4 g/mol), which gives it a high speed of sound, enabling faster pressure dynamics and better responsiveness.

High thermal conductivity

Helium has excellent thermal conductivity, making it ideal for efficient heat exchange between the gas and the hot/cold surfaces.
This minimises thermal losses and ensures better coupling between the gas and heat exchangers.

Nearly ideal gas behaviour

Helium behaves very much like an ideal gas, even at high temperatures and pressures.
This makes it predictable and stable in thermodynamic cycles where temperature and volume vary continuously.

Low viscosity — Lower friction losses

Its low dynamic viscosity reduces internal friction and minimises pumping losses through regenerators and heat exchangers.
This contributes to a higher mechanical efficiency.

Inert and safe

Like gold, known for its conductivity properties and resistance to tarnish, Helium is called a noble gas because it does not react chemically with machine materials that cause oxidation, corrosion and wear, resulting in longer life properties and stable operation.

Typical applications

Helium is commonly used in:

Stirling engines for power generation and for heat pumping.
Aerospace and high-performance HVAC systems.

Helium’s high efficiency in Stirling machines delivers because it:

Has a high speed of sound — responsive pressure oscillation.
Conducts heat efficiently.
Behaves like an ideal gas.
Has low viscosity — low losses.
Is inert and safe for long-term use.