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In this paper, the design of an Organic Rankine Cycle (ORC) is optimized by means of numerical simulations. The systems of interest are the subcritical and transcritical thermodynamic cycles.Optimizations are performed with the objective of determining the design that maximizes the specific power output. The design variables include the operating parameters (pressures, mass flow rates), and the best working fluid is determined by comparing the performance of 36 refrigerants. Optimization runs are performed for a wide range of geofluid temperatures (from 80 to 180°C), and for a wide range of condenser temperature (from 0.1 to 50°C). The results are summarized in charts that may be used as efficient tools for designing optimal geothermal power plants. Finally, an approximate analysis allowed to develop new correlations for predicting the maximal specific power output of an ORC.

The effect of Nafion ionomer content on performance of a PEM fuel cell operated with homemade anodic and cathodic electrodes fabricated from a novel MOF derived Pt-based electrocatalyst was investigated via numerical simulation and experimental measurement. First, the parameter sensitivity analysis was performed to identify the most influential parameters of the model. Then, these parameters were calibrated for different fuel cell designs investigated in the current study by employing the corresponding experimental data. Afterward, the calibrated model was used to examine the impact of Nafion content in the catalyst layer of home-made electrodes. Finally, the qualitative trend predicted by this model was experimentally surveyed by varying the Nafion content between 10-50 wt.% in the catalyst layer of home-made electrodes. At the anode side, the performance of home-made electrode in a PEM fuel cell demonstrated small dependency on Nafion content. For the cathodic home-made electrode, Nafion content was found to affect the PEM fuel cell performance more strongly. Although the model could correctly capture the impact of Nafion content on calculated polarization curves, the model predicted optimum values significantly deviate from the experimental results. This was related to the several simplifications made during model development.