Evaluation of Plant Configurations for Geothermal Trigeneration Systems with Organic Rankine Cycles

Due to the expected increasing importance of cooling applications within the next decades, geothermal trigeneration systems might be of high interest in the future. This work aims at evaluating different plant layouts against the background of more advanced plant configurations and part load behavior. Four different plant configurations are analyzed for a geothermal heat source with a temperature of 130 °C and a mass flow rate of 140 kg/s. The highest net power output is achieved by an advanced serialparallel configuration. With an annual net power production of 25.91 GWh, the power output is between 2 and 42 % higher compared with the other three configurations (parallel, serial and serial-parallel). The application of a recuperator within the ORC system has a significant impact on the serial concepts, but only marginally increases the power output of the parallel layouts. Depending on the plant configuration, there is an optimal desorber temperature of the absorption chiller. In case of serial concepts, the desorber temperature affects only the brine reinjection temperature, but not the ORC net power. For serial concepts, an optimal desorber temperature between 65 and 70 °C is revealed. Finally, the results highlight the importance of considering part load effects when evaluating the annual performance of geothermal trigeneration systems.