COMPACT ORC UNIT FOR GEOTHERMAL APPLICATION A SHORT DESCRIPTION OF FUNCTIONAL SPECIFICATION Author: Date: André Charles Mintsa May 2021 Compact ORC unit for geothermal application

PAPER GENERAL OVERVIEW 1. PURPOSE OF THE PAPER This paper is related to a process of electricity and thermal power generation using geothermal heat throughout an Organic Rankine Cycle module. Low temperature and low flow issued from geothermal applications is the main challenge when designing such a module. This paper details the technical specifications of the ENOGIA’s standard ORC and the modifications that are carried out to adapt for geothermal application. The paper covers most important aspects of the module, hydraulic, electrical, integration matters, monitoring and the most critical part...

In the cycle, the working fluid is pressurized and pumped to a heat exchanger where it is evaporated. At this the stage the working fluid has reached a gas phase at high pressure. It then passes through the turbine where it is expanded and cooled through a heat exchanger (the condenser) where it condenses back into liquid phase. Main components of ORC are: • • • • • • Enogia micro-turbine: to convert the mechanical energy from gas expansion into electricity Centrifugal pump: to pressurize the working fluid Evaporator (Plate Heat Exchangers): to transfer the heat from the geothermal fluids to...

For geothermal application, standard ORC has been modified to meet geothermal constrains, particularly geothermal fluid characteristics. The critical component for a geothermal application is the evaporator, mainly because of corrosion issues. The ORC module has integrated different kind of heat exchanger, as Gasketed Plate Heat Exchangers which allows a better adaptability, easy cleaning and maintenance. 2.1.1. Condenser Enogia’s standard machine integrates both BPHE evaporator and condenser. Nevertheless, the role of this later heat exchanger is to extract heat from the working fluid to the...

Container packing As unit may be moved from one site to another, the ORC is integrated in a dry maritime container. If no cold source is available at site, Enogia can provide a turnkey assembly which includes the cold source, composed of a circulating pump, a dry cooler and cold hydraulic connections. The following gives an idea of the turnkey system. Figure 4: Hydraulic connections dimensions for container packing Compact ORC unit for geothermal application

Figure 5: Dimension of dry 20 ft container. Figure 6: ISO view of the ENO-40 LT turnkey machine Compact ORC unit for geothermal application

8.1.1. Heat Source • Temperature range: 70 – 120 °C • Thermal power input range: 450 – 640 kW • Hot source medium: Water, steam, oil. • Max mass flow: 83 m3/h • Hydraulic connection: Flange ISO DN80 PN16 9.1.1. Cold source • Temperature range: 0 – 60 °C • Max mass flow: 83 m3/h • Working fluid: Water, Water + glycol. • Hydraulic connections 10.1.1. Grid Connection • Maximum gross electric power [kWe] 40 kW • Grid connection 400V, 3ph neutral + earth, 50-60 Hz. The ENO 40 LT is totally autonomous. The PLC controls the system operations in order to use all available heat. On-site data logging and...