In this work, a newly developed dynamic model is used to evaluate the performance of fuel handling lines between a liquid hydrogen storage tank and a micro gas turbine (mGT). Such a system has been calibrated around a real facility, which will provide data for validation in the near future, towards the objective of assessing the real potential of zero emission power generation solutions, also suitable for marine propulsion. The H2 fuel lines are modelled using a two-phase liquid hydrogen tank, a simplified pressurizing pump, a 1D superheater/vaporizer for the pressurized hydrogen, a buffer tank, and the fuel preparation and transport lines leading to the mGT. The resulting system dynamic model is used to predict the behaviour for various hydrogen demand profiles, corresponding to changes in the power output of the associated mGT, or changes in the set concentration of hydrogen in the NG-H2 fuel blend. The ability of the system to follow variable loads or concentration curves is evaluated and discussed, as well as analysis of crucial components, which may become limiting factors for certain operating conditions and transients. The model has been developed in TRANSEO, a modelling library tool by the Thermochemical Power Group (TPG) of the University of Genoa for the dynamic analysis of gas turbine cycles, whose library of components has been upgraded to cope with the specific application, and linked to REFPROP tool by NIST for thermos-physical properties. Results show that the design for the heating system, which is sized to avoid freezing of the heat exchange fluid, may be considerably oversized. While the temperature of the water-glycol heating solution is reliably observed within a 3°C margin between inlet and outlet, for particularly low mass flow rates of hydrogen, temperature disturbances of up to 20°C could be observed at the exchanger outlet when re-starting the flow of hydrogen through the evaporative lines. However, the outlet temperature is otherwise well-controlled with a simple proportional-integral-derivative control structure, with disturbances remaining within 3°C when the mass flow of hydrogen is not brought too low. With further precautions in place, the outcome could be encouraging for the prospective integration of this system into a naval context, targeting emissions reduction and safety compliance.
Liquid Hydrogen Storage System for Micro Gas Turbines: Dynamic Modelling and Performance With Variable Demand Profile
Tucker, Swatara;Passalacqua, Matteo;Dotto, Alessandro;Traverso, Alberto;
2025-01-01
Abstract
In this work, a newly developed dynamic model is used to evaluate the performance of fuel handling lines between a liquid hydrogen storage tank and a micro gas turbine (mGT). Such a system has been calibrated around a real facility, which will provide data for validation in the near future, towards the objective of assessing the real potential of zero emission power generation solutions, also suitable for marine propulsion. The H2 fuel lines are modelled using a two-phase liquid hydrogen tank, a simplified pressurizing pump, a 1D superheater/vaporizer for the pressurized hydrogen, a buffer tank, and the fuel preparation and transport lines leading to the mGT. The resulting system dynamic model is used to predict the behaviour for various hydrogen demand profiles, corresponding to changes in the power output of the associated mGT, or changes in the set concentration of hydrogen in the NG-H2 fuel blend. The ability of the system to follow variable loads or concentration curves is evaluated and discussed, as well as analysis of crucial components, which may become limiting factors for certain operating conditions and transients. The model has been developed in TRANSEO, a modelling library tool by the Thermochemical Power Group (TPG) of the University of Genoa for the dynamic analysis of gas turbine cycles, whose library of components has been upgraded to cope with the specific application, and linked to REFPROP tool by NIST for thermos-physical properties. Results show that the design for the heating system, which is sized to avoid freezing of the heat exchange fluid, may be considerably oversized. While the temperature of the water-glycol heating solution is reliably observed within a 3°C margin between inlet and outlet, for particularly low mass flow rates of hydrogen, temperature disturbances of up to 20°C could be observed at the exchanger outlet when re-starting the flow of hydrogen through the evaporative lines. However, the outlet temperature is otherwise well-controlled with a simple proportional-integral-derivative control structure, with disturbances remaining within 3°C when the mass flow of hydrogen is not brought too low. With further precautions in place, the outcome could be encouraging for the prospective integration of this system into a naval context, targeting emissions reduction and safety compliance.
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