The ENEFCOGEN cleantech technology is based on volumetric spiral turbines "Scroll Turbines" in a mini ORC system "Organic Rankine Cycle", which works with thermal sources at low temperature (between 120°C and 200 °C).
Very popular on the market for many years, the Scroll compressors are known for their efficiency and robustness, and this for various applications such as ventilation or refrigeration. Eneftech developed the expertise to use these scrolls compressors as turbines in order to generate electricity. Within this scope, we specialize in new solutions adapted to the turbine scroll Cogeneration.
Thus our ENEFCOGEN modules are built with standard scroll turbines (market compressors converted into turbines) or with Eneftech new generations turbines (High Tech Scroll Turbine). Thereby Eneftech offers a wide range of products aiming at stationary or mobile applications:
- Combined production of electricity and heat by promoting renewable energy or recycling of waste heat in industry processes.
- Production of electricity from the emissions of a hybrid motor vehicle by valuing the exhaust gas of the engine.
The generation of electricity from thermal sources at low temperature is possible through the use of organic fluids (refrigerants) moving turbines on the same principle as the famous steam cycle, hence the name ORC cycle stands for "Organic Rankine Cycle". These refrigerants are much more efficient when used with heat at low temperature (below 300°C) for low power applications (from a few kW to several MW).
The figure above shows an example of this cycle, including an evaporator, a turbine, a condenser and a pump. Steamed high pressure fluid (refrigerant) is generated in the evaporator when heated by a heat source (eg boiler, solar heat or waste exhaust gas from a cogeneration engine). This refrigerant vapor is expanded in the turbine, generating electricity through an electrical alternator. Then, the steam leaving the turbine is condensed in the condenser using water or air, as coolant. The organic liquid obtained from the condenser is finally pumped to the evaporator to complete the cycle.
The benefits of the Eneftech ORC :
A good efficiency thermodynamic cycle
A good turbine performance with operating pressures suitable for organic fluids
Very attractive Thermodynamic properties of fluids, namely: a high molecular
weight and low mass volume
An expansion without condensing with a non overheated working fluid
The adjusted speed of rotation, allowing a direct coupling of the generator to the grid
Silent operation with a low vibration level, requiring virtually no maintenance
The standards Eneftech Scroll turbines are converted from compressors spiral units (or scroll type), well known in the market for their efficiency and robustness. The scroll compressor units are widespread and are produced and sold by many companies. It's a simple device with few elements, which ensures low cost and high quality. In addition, the machine produces very low Scroll mechanical vibrations (low noise) and has a process of expansion quasi-continuous with an excellent volumetric efficiency.
The right figure shows the elements constituting the hermetic turbine scroll unit. A volumetric expansion chamber bounded by two volutes, a fixed one at the top and a mobile scroll below, the assembly is positioned with a phase shift of 180 º to form a successive series of sub-expansion separated chambers. The mobile scroll is mounted on a shaft having eccentric bearings system and a particular mating (Oldham ring) for performing an orbital motion relative to the fixed scroll, and by a simple rotation of the shaft.
The orbital motion of the mobile scroll increases the volume of these chambers, moving from center to periphery. Thus, during the expansion, a high pressure refrigerant gas is introduced at the center of the unit by forming a central pocket of gas (figure to left, position 1). This gas, gradually is moving towards the periphery (positions 1-8), reaches its discharge pressure and escapes at the sides of the devices (figure to right, position 8-1).
An asynchronous electric generator is coupled to the drive shaft and the assembly is isolated from the atmosphere by forming an envelope, thus constituting the sealed unit.
The next generation scroll turbine is a spiral turbine with a high volume ratio, working with temperatures of about 200°C, and currently under development.
Its characteristics are chosen to meet the needs of many applications at low power (1-5 kW) where a reduced costs of auxiliary components (electronics, pumps, ...) is required, along with an improved power density.
Maximum inlet temperature: 200 ° C
Rotational Speed: 1500 - 6000 rpm
Maximum Power: 5 kW
Different configurations of the machine it will be operational in single-stage or two-stage, and with different refrigerants.