COGETHERM EMA-50 POWER GENERATION MODULE

Its performances make it ideal for primary power production as well as for waste heat recovery and other low-temperature applications (e.g. geothermal power). Said thermodynamic cycle in fact, thanks to a special fl uid medium, can off er optimal performances in a plant this size, as well as having several advantages over the operational cycles of traditional steam engines and turbines:

• Low Operational Temperature allowing the use of “weak” thermal sources.

• High Condensing Temperature

• No Turbine Blade Erosion which gives higher reliability and lower maintenance costs.

• Low Operational Pressure (max 6 bar) meaning higher safety levels, less legal implications, and lower plant costs;

• No Atmospheric Exhaust as the Rankine cycle is a closed cycle.

• No Water or Steam Consumption leading to lower management costs, less bureaucracy, lower plant complexity.

• Low Noise Levels allowing operators to work without hearing protection and leading to less controversies in residential installations.

EMA 50 modules have been custom designed from scratch with the purpose of becoming the power generati on stage of small power CHP (Combined Heat and Power) plants and heat recovery systems, so to increase efficiency as much as possible we implemented several performance- boosting engineering solutions such as:

• Low Operational Temperature allowing the use of “weak” thermal sources.

• High Condensing Temperature

• No Turbine Blade Erosion which gives

• Direct Turbine-to-Generator Coupling which eliminates the performance losses inherent in gearboxes.

• Custom-Designed Inverters for each model of module, to obtain optimal output performance.

All of this contributes to give our systems a high thermal efficiency, which in optimal conditions allows them as total system efficiency (thermal power input vs electric power output) up to 9.6%, a very high value for a system this size

THE WORKING FLUID

The special working medium we use is the key component which made studying and creating these high-tech solutions possible. The organic medium used in the system WE proposes has the following excellent specifications:

• Wide working range (60-165°C) which allows exploiting low-temperature heat sources once thought useless, such as geothermal sources and engine cooling.

• High condensing temperature

• Completely dry in all of its states thus avoiding cavitation and turbine blade erosion.

• Non-toxic, non-flammable, 100% biodegradable and ozone-friendly so even accidental spills are not hazardous.

• Requires little or no reintegration as it works in a closed cycle.

• Requires no filtering/reconditioning thus reducing plant complexity and size.

THE LOW-TEMPERATURE ORGANIC RANKINE CYCLE

The Rankine Cycle concept, invented in the 1800s by the scottish physicist William Rankine, is quite simple and easily explained with a diagram like this one

A heat source warms up a heat exchanger which transfers the heat to a liquid organic medium, which – exposed to that heat – becomes a gas, greatly increasing its volume. This expanding gas drives a turbine generating mechanical energy (Wout) which can be converted into electric power by a generator connected to the turbine shaft . On leaving the turbine, the medium - in gas form - is conveyed to a condenser, where it cools down returning to its liquid state. Collected in a special tank it is then pumped back to the heat exchanger, thus closing the cycle, the low-temperature excess heat the medium releases in the condenser (Qout) can be eefficiently used for other uses such as ambiental heating, fuel desiccation preheating and so on (combined generation of heat and power).