Our Heat Pump

What is a heat pump?

A heat pump (HP) is a device that transfers thermal energy (”heat”) from a heat source, relatively cold, to a heat sink, relatively hot. The work required for the transfer is usually provided by an electrical energy input, resulting in a higher thermal energy output.
While electrical resistors can also convert electricity into heat with 100% efficiency, heat pumps are more efficient, typically delivering 2 to 5 kWh of heat for 1 kWh of electricity consumed. The ratio of the heat output to the electricity input is called the Coefficient Of Performance (COP) of the heat pump.
Of course, heat pumps do not create energy from nothing: they merely redirect the flow of energy from cold matter to hot matter. A fridge is a heat pump: the engine inside the fridge forces the heat to flow from the cold part of the fridge (the inside) to the hot part of the fridge (the serpentine tube usually at the back of the fridge). In this regard, heat pumps do for heat what hydraulic pumps do for water: they can “force the heat to flow backwards”, just like a hydraulic pump can force the water to flow uphill by expending mechanical energy.
Therefore, when a heat pump delivers 3 kWh of heat, it typically takes 2 kWh from a cold source, adds in 1 kWh from the electrical energy consumed by the engine, and delivers 3 kWh of heat to the hot sink. A COP of 3 was obtained is this example, and the higher the COP of the heat pump, the more energy can be saved compared to less efficient alternatives.

Airthium's heat pump

Airthium’s technology disrupts the century-old Stirling engine concept to turn it into a highly reliable, low-cost, very-high-temperature heat pump.
Our core innovation relies on a breakthrough in high-temperature, fast, near iso-thermal gas compression to achieve a near-ideal Ericsson cycle in our heat pump (which is close to the well-known Stirling cycle).
  • 01.

    Stirling engine (fluid = helium)

    • T = 100-550°C, Load following, batch processes
  • 02.

    Fast near-isothermal compression

    • COP up to 3.5
    • Up to 86% of Carnot efficiency
  • 03.

    No sliding/rotating seals

    • 5x less maintenance

High temperature

High-Temperature Heat Pumps (HTHP) operate as conventional HP but at higher heat sink temperatures. Commercially available HTHP can supply heat between 100°C and 160°C today. Airthium’s HTHP high boundary is 550°C, a range that positions our HTHP as a disruptive technology. Our heat pump uses Helium (R704) as the working gas, and various heat transfer fluids depending on the source and sink temperatures.

High lift

The lift is the difference between the heat sink and the heat source temperatures.
Our heat pump harvests available waste heat at any temperature up to 930°F/500°C, or atmospheric heat down to -60°F/-50°C, depending on the available heat source, and upgrades it up to 550°C heat. While in existing HTHP the maximal lift is around 80 °C, Airthium’s lift is up to 500 °C and it impacts directly the HP efficiency.

High efficiency

Depending on the source and sink temperatures, it can achieve up to 86% of Carnot’s efficiency, compared to about 60% for best-in-class high temperature heat pumps today. This results in achievable COPs as high as 3.5.

High glide & flexibility

It even works with intermittent processes requiring heat in bursts/duty cycles, or heat at temperatures that strongly vary in time (high glide).

Low maintenance

Its extremely simple mechanical design allows very low maintenance and downtime, notably thanks to the absence of high-temperature sliding or rotating seals.
Source (in) temperatureSupply (out) temperatureHeat transfer fluid combination (cold side - hot side)
20°C – 80°C
68°F – 176°F
200°C – 550°C
392°F – 1022°F
Water –Molten salt (HITEC or Nitrate)
200°C – 520°C
392°F – 968°F
230°C – 550°C
446°F – 1022°F
Molten salt – Molten salt (HITEC or Nitrate)
-50°C – 220°C
-58°F – 428°F
-20°C – 250°C
-4°F – 482°F
Thermal oil – Thermal oil
-50°C – 250°C
-58°F – 482°F
200°C – 550°C
392°F – 1022°F
Thermal oil – Molten salt (HITEC or Nitrate)