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van Heule, Xander
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van Heule
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Xander
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Xander van Heule
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Optimizing the performance of a hybrid Solar-Biomass micro-CHP system with a TFC engine as the prime mover for domestic applicationsSkiadopoulos, Anastasios; van Heule, Xander; Lecompte, Steven; De Paepe, Michel; Manolakos, Dimitriossolar energy and biomass with a Trilateral Flash Cycle (TFC) engine as the prime mover is simulated and optimized in this work. The system is sized to meet the Space Heating (SH) demand of a typical multi-family building in Athens, Greece. Particular attention is paid to the challenging two-phase expansion phenomenon, the factor mainly affecting the efficiency of the TFC, under off-design and partial load conditions. Under optimized operating conditions, the average annual CHP efficiency, TFC thermal efficiency, and solar energy conversion efficiency were estimated to be 89.2%, 8.4%, and 4.3%, respectively. The TFC can cover 18% of the building’s SH demand and 40% of its electricity demand, with the Levelized Cost of Electricity (LCOE) and Levelized Cost of Heat (LCOH) in the range of 0.21~0.28 €/kWhel, and 0.065~0.087 €/kWhth, respectively. Furthermore, PayBack Periods (PBP), between 15 and 25 years, can be anticipated, when current market energy prices are considered.- Optimization of a Partially Evaporating Organic Rankine Cycle with thermal non-equilibrium expansion.van Heule, Xander; Skiadopoulos, Tasos; Manolakos, Dimitris; De Paepe, Michel; Lecompte, StevenThe Trilateral Flash Cycle (TFC) is an alternative to the Organic Rankine Cycle (ORC). The TFC have been shown to have greater exergy efficiencies compared to the ORC in low-grade heat-to-power conversion. This is a result of the more efficient heat transfer from the heat carrier to the working fluid, even though the TFC has inherently a lower thermal efficiency. However, these results are based on cycle modeling assuming equilibrium conditions, but the actual two-phase expansion process is a nonequilibrium process. Thermal non-equilibrium between vapour and liquid occurs during the evaporation (or flashing) of the working fluid during the two-phase expansion process. The liquid phase has a temperature greater than the corresponding pressure’s saturation temperature and the equilibrium assumption overestimates the actual vapour quality. In a previous work, this non-equilibrium expansion was modeled and predicted based on the homogeneous relaxation model (HRM). In this work, the impact of the non-equilibrium process on the efficiency of the TFC is investigated and compared to the equilibrium model. The overall power recuperation is around 86% lower when including the thermal non-equilibrium nature of the expansion process. Therefore, the thermodynamic non-equilibrium losses should thus be incorporated when predicting the performance of a TFC.
