EN3 - Tech-info

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This investment carries considerable risks and may lead to a loss of the entire assets invested. Projected returns cannot be guaranteed and may be lower than expected.

EN3 | Videos

1.       Basics

Our energy conversion system is based on the Rankine cycle, which was named after the Scottish physicist and engineer William John Macquorn Rankine and is successfully used in all modern large-scale power plants today. The Rankine cycle is a thermodynamic cycle for the conversion of thermal energy into mechanical work.

So far, steam expansion machines (expanders) suitable for the use within small power ranges have not existed. Consequently, the processes used in large power plants could not be transferred to smaller energy systems such as the engines of biogas plants, trucks, or cars. Large power plants mostly use turbines. However, using turbines in small systems is unattractive because of the high production costs. Another major disadvantage of small turbines is their low rate of expansion efficiency. Turbines must have a certain gap (clearance) between the rotating element and the housing. Steam passes through these gaps and thus reduces the efficiency of the turbine. Power losses in turbines below 100 kW are disproportionately high, making such turbines inefficient.

As our waste heat usage system is independent of the type of heat source, it provides numerous potential applications in the area of electricity generation from residual heat and waste heat. Initially, EN3 focuses on generating electricity from the exhaust gas energy of internal combustion engines.

The internal combustion engine is the most important technology for generating electricity or mechanical power around the globe. It is used in cars, ships, or decentralized power plants (CHP, biogas plants) to generate electricity. Even though this technology has been optimized continuously over time, as much as approx. 60 % of energy stored in the fuel are still emitted to the environment unused through the coolant and through exhaust gas heat. This is precisely what our solution tries to change.

The EN3 energy conversion system consists of a vaporizer, an expansion machine (expander), a condenser, and a feed pump.

In the EN3 system, the thermal energy stored in exhaust gases (approx. 450 °C hot) from an external source of heat (e.g., from an internal combustion engine) passes through the steam generator (1). In this generator, a working fluid (water or an organic working fluid) is vaporized. The pressurized vapor is passed on to an expander (2), where it is depressurized and performs technical work. By means of an attached generator, the pressure energy stored within the vapor is converted into electricity. Having passed through the expander, the depressurized vapor enters a condenser (3), where it is liquefied and fed back into the cycle via the feed pump (4).


The Thermodynamic Cycle of an Energy Conversion System


2. Operation of the Steam Expander in Detail

The sequence of motions is similar to that in a conventional Wankel engine. Unlike such Wankel engines, however, the EN3 machine possesses a digon piston that enables greater changes in the volume.

Inside the expander, a piston rotates on an eccentrically mounted shaft. The pressurized vapor enters the working chamber of the expander through the inlet valve. In so doing, the pressurized vapor exerts a force on the piston. This force leads to an increase of the expansion chamber, during which work is performed. Via the output shaft, the mechanical work is finally transferred to the outside and converted to electricity in a generator. While an expansion takes place above the piston, the depressurized water vapor is emitted below. Because of this principle of operation, the machine reaches a very high power density.

Since the working chamber is actively sealed, leakage losses remain low, and the steady rotation also causes friction to be at a minimum. As a result, efficiency is high, whereas wear and tear are extremely low.


Working Principle of the EN3 Expander (O = Outlet Valve; I = Inlet Valve)


The expansion machine may be scaled to any size, which is why it is also suitable for mobile applications. Such applications include the areas of ships and rail vehicles and the area of commercial vehicles.

Another advantage of the machine is its steady sequence of motions (there is no reversal of motion as in piston machines). Consequently, by combining the right materials, we can achieve long lifespans.

Since it can balance gas and inertia forces completely, our machine runs very smoothly and free of vibration.

The machine's modular design makes it possible to link multiple wheels. Similar to the cylinders in a multi-cylinder engine (e.g., an internal combustion engine in a car), each wheel represents a separate working chamber (cylinder). Thus, we can react very flexibly to various customer requirements in regard to different power ranges. 


Single-Wheel and Multi-Wheel Versions of the Steam Expander


3. Products and Customer Benefits

We produce ecologically and economically sustainable energy conversion systems for our customers. The EN3 technology focuses mainly on systems for using the exhaust gas heat of internal combustion engines. Our system converts this exhaust heat to electricity. Internal combustion engines are used around the globe, e.g., in combined heat and power plants (CHP), biogas plants, trucks, cars, and ships. Our technology increases the efficiency of such engines significantly, and it reduces fuel consumption and the related emissions.

While developing our technology, we had the important goal of achieving low production costs through suitable system concepts and product design. We use water as the working fluid in the entire energy conversion system. Water is insensitive to high inlet temperatures and thus makes system production less expensive.   Some of our competitors, on the other hand, rely on organic fluids instead. We see some limitations there because organic fluids may have a negative impact on the environment or because they may harm people in the case of accidents.

Even at very early stages, we have made sure that our expansion machine has a high degree of standardization so that it may be produced very inexpensively. Our expansion machine consists of only 85 components. By comparison, an engine consists of several hundred components. Consequently, high-quality production "made in Germany" is possible at low costs. In the case of the components for the energy efficiency system, we have also been able to realize an inexpensive design by using common components available on the market. As a result, our customers may purchase a system that is highly attractive in economic terms and whose purchase will pay off in no time.


The EN3 Expansion Machine as a Two-Wheel Version and within the Powerblock


Our customers, the environment, and the development of EN3 equally benefit from this fact. Our systems make engines more efficient and significantly reduce their power consumption. Consequently, they also reduce harmful emissions such as carbon dioxide, sulfurous oxides, or nitrogen oxides considerably. At the same time, customers may reduce their energy costs significantly and achieve attractive returns over short payback periods.

Therefore, investments in heat recovery systems become ecologically valuable and economically sensible. We have installed the first system at a Danish subsidiary of one of our major technology partners from Sweden. There, we conducted on-site performance tests and optimized the system. The first system in Germany will be set up in a biogas plant near Rostock toward the end of 2014 or the beginning of 2015. 


4.  Unique Selling Points

The table below provides an overview of rival technologies with a qualitative classification of the key criteria: internal efficiency, expansion ratio, lifespan, and production costs. It has to be considered that the thermal efficiency of the system in which the expander is installed depends on the internal efficiency and on the expansion ratio. The larger both values are, the better the thermal system efficiency is. 

Qualitative Comparison of Expander Concepts in Regard to Key Characteristics


Apart from our rotary piston machine, reciprocating piston machines may also achieve efficiency rates of much more than 60 % within small power ranges. However, they have the significant disadvantage that their design is more complex, which also increases their production costs. Moreover, the oscillatory motion of the piston leads to increased wear and tear and reduces the lifespan.

Rival technologies often use organic working fluids (ORC systems). Our system may be used with both organic working fluids and water. Water has a number of advantages over organic fluids because it is insensitive to high inlet temperatures and enables direct vaporization in the exhaust gas flow.   We are thus able to construct systems that are simpler and less expensive than systems using organic fluids and that consume less power. Furthermore, water is neither inflammable nor carcinogenic or harmful to the environment in any way (e.g., ozone-polluting).


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€ 727,945


€ 475

Average Investment

10.82 %

Share Offered

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