Ener-G-Rotors Technology

The heart of the ORCA™ system is our patented, efficient, and economical TGE ™ expander

The Ener-G-Rotors device is unique as an expansion device in ORC, as it is a positive displacement pressure device. The enabling technology is a thermodynamic heat engine called the Trochoidal Gear Engine (TGE™). Designed from a simple gerotor expander, the TGE™ is nearly frictionless and has been proven to be more efficient and cost effective than existing technologies, when used in an organic Ranking system. The TGE™ is basically composed of two rotors spinning on slightly different axes. The slight offset of the axes creates gaps between the rotors that move from an inlet port to an outlet port.
Fluid vapor enters the TGE™ in small volume at high pressure and high temperature. This pressure forces the engine to rotate; as the engine rotates the vapor expands in volume. As the vapor expands it loses pressure and temperature and the energy from that conversion is translated into the rotary motion of the engine. The vapor leaves the engine when it reaches the exit port.
The TGE™ is a unique heat-to-electricity technology, as no other technologies can work economically at the same sizes and temperatures. The increased efficiency and reduced costs of the expander and system creates a new opportunity for small scale, low temperature, heat-
to-electricity conversion.


► High isentropic efficency
► Inexpensive
► Simple
► Durable
► Robust performance



Organic Rankine Cycle (ORC)



The Organic Rankine Cycle (ORC) is a thermodynamic process that enables low temperature waste-heat to vaporize a fluid and drive an expander to create electricity. The fluid is vaporized by the waste-heat and then expanded in a vapor expander, which drives a generator producing electricity. The spent vapor is then condensed to liquid and recycled back into the cycle.
The working principle of the Organic Rankine Cycle (ORC) is the same as the steam cycle (Rankine Cycle), except that instead of using water as the working fluid, a high molecular mass organic fluid is used. The high molecular mass fluid usually boils at a much lower temperature than water. This fluid enables recovery of heat from lower temperature sources such as industrial waste heat, stationary engine water jacket, combined heat and power systems (CHP), and geothermal heat.


The Cycle
1. Hot liquid, steam, or oil flows through the EVAPORATOR, transforming the liquid organic working fluid into a hot vapor.
2. The hot organic vapor enters the EXPANSION DEVICE, and expands as it goes through the expander, creating mechanical energy which drives a generator, creating electrical energy.
3. The organic vapor leaves the expander with a lower pressure and temperature, still a vapor.
4. The organic vapor inters the CONDENSER where it is cooled and condensed back to a liquid.
5. The organic vapor is then pumped back into the evaporator by the PUMP, where the cycle repeats.


ORC Expansion Devices

Most ORC systems run turbines or a compressor technology backwards as an expansion device. Typical technologies are screws (both single and twin), scrolls, and turbines. These technologies are flow devices and require very high flow rates, which in turn require large amounts of refrigerant (The TGE™ is a pressure device and requires far less refrigerant). At small sizes, other expander technologies have low isentropic efficiencies.

Isentropic Efficiencies

In the ideal cycle described by the expander’s theoretical model, the expansion is perfect and all possible expansion can occur. In any real cycle, only a part of the energy recoverable from the process is transformed into useful work. The other part is converted into heat and is lost, reducing the efficiency of the expander. The isentropic efficiency of the expander is defined by comparison with a perfect (isentropic) expansion. The higher the isentropic efficiency, the more efficient and cost effective the cycle.