Heat 2 Power-Engine []

Useful work: Steady-state temperature profile with high temperature differences

The entire Heat2Power‑Engine operates with stable, steady-state temperature conditions – without cyclical heating or cooling of components. The consistent separation of the high-pressure/hot gas section and the low-pressure/cold gas section generates consistently large temperature differences within the process.

• Separate High-Pressure and Low-Pressure Lines Unlike conventional Stirling engines, the working gas does not flow through alternating hot and cold lines. All flow paths are thermally unambiguous – mixed temperatures do not occur in the entire circuit.
• Separate High-Pressure and Low-Pressure Lines Unlike conventional Stirling engines, the working gas does not flow through alternating hot and cold lines. All flow paths are thermally distinct – mixed temperatures do not occur in the entire circuit.
• Low Temperatures in the Compression Cylinder Before entering the compression cylinders, the working gas is cooled in a controlled manner using an absorption chiller (AC). This creates temperature differences that are not achievable in conventional Stirling engines. The temperature after the AC forms a stable thermodynamic fixed point; changes elsewhere do not affect this value.
• No Thermal Shocks Since no components oscillate between hot and cold temperatures, no thermal shock loads occur. This increases the service life of the components and prevents temperature-induced material fatigue.
• Stable Process Control The clear thermal separation between the hot and cold sides ensures reproducible operating conditions and enables precise control of the entire system – regardless of load changes or external temperature fluctuations.

Optimized equipment requirements

• The Heat2Power-Engine is an impressively simple design, relying on a clear, modular structure with just a few key components.
• The amount of equipment required is minimal – without complex auxiliary components such as turbochargers, valve trains, or elaborate cooling circuits.
• Components are geometrically simple, modular in design, and therefore easy to manufacture, maintain, and scale.
• The Hypocycloid Gear replaces the classic crankshaft and ensures precise, low-loss movement of the pistons.
• A simple internal mechanism handles the basic control functions – robust, low-maintenance and free from complicated devices.

Versatility and variability

• The Heat2Power-Engine can utilize any suitable central heat source – from industrial waste heat and landfill gas to surplus power from renewable energy generation.
• The system is flexibly convertible to various fuel types (e.g., Diesel, bio-LNG, H₂) and is therefore ideal for maritime and industrial applications.
• This high degree of variability makes the system a key component of the energy transition: Direct reconversion of waste heat into electricity, decentralized backup power plants during periods of low wind and solar power generation, and smoothing and reconversion of surplus power using high-temperature thermal storage systems.

Efficient heat transfer

• Generously dimensioned heat exchangers The heater and cooler are located directly in the gas circuit lines. Their size is not limited by the cylinder head, which enables high heat transfer rates.
• Counterflow principle instead of heat conduction through thick walls External counterflow heat exchangers enable short heat paths and clear temperature profiles. The gas does not need to be heated or cooled through thick metal walls, as is common in classic Stirling engines.
• Stable temperatures through steady-state operation Stable operation prevents thermal fluctuations. The cold side can even be cooled below ambient temperature through recompression and targeted cooling, further increasing the usable temperature difference.
• Suitable for large quantities of heat Counterflow heat exchangers can absorb and release significantly larger quantities of heat than the heat-conducting structures of classic Stirling engines.
• Constant heat transfer conditions The quasi-continuous mass flow in the gas circuit avoids the cyclical flow fluctuations of classic Stirling engines. As a result, the heat exchangers always operate within their optimal operating range without dead times.

Thermodynamic efficiency:

• Modified Stirling Process with Realistic State Changes The Heat2Power-Engine does not use idealized isothermal processes, but rather realistic adiabatic and polytropic state changes with high pressure gradients. This significantly increases the useful work output per cycle.
• Full Utilization of the pV Diagram The process states are almost fully utilized. The four operating phases barely overlap; each state change is clearly delineated and thermodynamically well-defined.
• Clear Temperature Profile without Mixing The amount of gas heated or cooled corresponds exactly to the amount expanded or compressed. Unlike conventional Stirling engines, no mixed temperatures occur.
• High compression ratio for more useful work The compression ratio is not limited by fuel properties. The higher compression results in significantly more useful work and a considerably increased power density.
• Significantly higher power density The power density is up to three times higher than conventional Stirling engines and 10–50% higher than diesel or gasoline engines – while maintaining stable temperatures.

Low internal losses:

• Generous Flow Cross-Sections All lines in the gas circuit have sufficiently large diameters. The classic trade-off between "low flow resistance vs. low dead space" is completely eliminated.
• Low Purge and Charge Change Losses The clear separation of the gas flows and the short filling and emptying paths result in only minimal pressure and flow losses.
• No Auxiliary Units with High Energy Consumption The Heat2Power‑Engine does not require energy-intensive auxiliary units such as blowers, pumps, or internal regenerators. This keeps the energy consumption very low.

Reduction of heat loss:

• Adiabatic process steps Adiabatic expansion and compression generate large temperature changes within the working gas. Because no heat is exchanged with the surroundings during these steps, there is no need to dissipate compression heat or supply expansion heat through the cylinder walls, which significantly reduces internal heat losses compared to systems that rely on quasi‑isothermal behavior.
• Same wall temperatures in both cylinder chambers Since the hot and cold gas flows are strictly separated, both chambers of a cylinder have the same wall temperatures. This largely prevents unwanted internal heat flows.
• Thermally separated gas paths No mutual heating or cooling through shared pipes; the working gas does not carry heat away from the working cylinder through heated pipes during the exhaust stroke, as is the case with a standard machine. The clear separation of the high-pressure/hot gas area and the low-pressure/cold gas area prevents mixing temperatures and minimizes heat transfer between the process areas.
• Isolatable Components All components can be selectively thermally insulated. Enclosing the system also allows for the controlled use or minimization of radiant heat.
• Efficient Use of External Heat Sources Waste heat is not released uncontrollably, but can be selectively fed back into the process via external heat exchangers or storage systems.

Wear

• Pistons do not serve as an external seal – they operate with a small gap to the cylinder wall.
• The piston rod is guided outside the cylinder chambers – i.e., outside the hottest areas.
• Little or no lubrication is necessary – e.g., through the use of plastic plain bearings.
• Oil-free operation of the compression cylinders is possible.
• Very few sealing points – and only outside the hottest areas.
• Short pistons, hollow piston rods and low rotational speeds → low inertial forces.
• Gas buffer at the end of the cycle and low rotational speed → reduced inertial forces.
• Linear arrangement of the cylinders (boxer engine) ensures pressure peak compensation – dead centers cancel each other out.

Show more technical details on thermodynamics

– Adiabatic Expansion (n = κ): steep pressure curve with a high pressure difference.
– Isothermal Expansion (n = 1): flatter pressure curve.

Low friction losses

• No lateral forces act on the pistons – resulting in low friction and no need for guide seals.
• Flat piston geometry in the double-acting cylinders → only two piston rings per double-acting cylinder pair (= four chambers) are required.
• Piston rings do not serve as an external seal – a minimal gap and low contact pressure are sufficient.
• Gas sealing is concentrated in the piston rod areas – only there do significant friction losses occur.
• Leakage flows occur exclusively on the crankshaft side – a maximum of two small potential points for four chambers.

Comparison of a 2-cylinder machine with other machines

High efficiency and energy yield:

• High thermodynamic efficiency due to large temperature difference and high compression.
• No cyclic heating/cooling of components – stable temperature control reduces losses.
• Compression ratio is not limited by fuel properties – compression occurs independently of the fuel type.
• No waste heat via the exhaust gas – heat remains in the system and can be recovered.
• Frictional heat, recovery heat, and radiant heat are utilized effectively – e.g., for combustion air preheating.
• Heat recovery systems can be easily integrated – e.g., through enclosure or recuperators.
• The theoretical Carnot efficiency is almost achieved – thanks to stable process control and a large ΔT.
• Overall efficiency significantly exceeds that of all known heat engines.

Environmental friendliness:

• The machine's high efficiency means low energy consumption – less fuel used per kWh.
• Central burner with continuous heating – no explosion, no unstable flame front.
• Use of low-emission burner concepts such as Flameless Oxidation (FLOX)  , Poreburner , oder COSTAIR-burner  -technology ispossible.
• Fuel-free operation during the power cycle: Energy transfer via heat, not combustion in the cylinder.
• The system can also be operated with industrial waste heat, biogas, or surplus renewable electricity – a wide range of fuel options.
• Ideal for decentralized power generation or storage solutions – for example, with High-Temperature Thermal Storage.

Economic efficiency and costs

• Investment in High Efficiency The Heat2Power‑Engine is designed as a high-quality industrial plant. Its exceptional thermodynamic efficiency unlocks energy that is wasted in other systems – creating economic benefits that far exceed the initial investment.
• Low Operating Costs Stationary operation, low internal losses, and the elimination of wear-intensive auxiliary components significantly reduce operating costs.
• Long Service Life Constant wall temperatures, no thermal shock, and low mechanical stress result in an exceptionally long service life for the plant.
• High Energy Yield from External Heat Sources The Heat2Power Engine achieves its highest efficiency when operating with external burners – for example, as a replacement for turbines or conventional gas-fired power plants. The highly efficient use of the supplied heat significantly reduces specific energy costs.