The present work focused on the upcoming technology of using water electrolysis to produce hydrogen and oxygen gas, which then are combusted in a bipropellant thruster to produce thrust. A comprehensive literature review was undertaken and the need for numerically modelling the Water Electrolysis Propulsion (WEP) system was identified. The process of conceptually designing the system was split mainly into 2 parts – the first was to develop a MATLAB®-Simulink® model of the entire system and the second was to use the Simulink® model for model-based optimization to achieve a 1 N thrust and highest possible specific impulse. The WEP system was mathematically modelled in Simulink® as a pressure-fed system which was tested with a few design choices taken from literature. The model was found to successfully simulate the working of the system. Chamber pressure, mass flow rate of propellant and cone half angle(s) of convergent and divergent section of nozzle were chosen as the design variables to minimize the cost function (a function of thrust and specific impulse). Genetic Algorithm was selected for the optimization and an average thrust of 1 N and a very good specific impulse of 338.9 seconds, with just 0.38 g of propellant per fire, were achieved. Also, the WEP system reported a Total-impulse-to-power ratio (TI/P) of 1.19 N-s/W. The design variables were then used to size the entire system, which fit in a 2U volume, ideal for a 6U or a bigger CubeSat. In the future, this numerical model of the entire system can be used as it is, to conceptually design a WEP system. Modelling of the system could be made more realistic by considering real gas instead of ideal gas and also considering zero-g effects of the outer space.
Il presente lavoro si è concentrato sull'imminente tecnologia di utilizzo dell'elettrolisi dell'acqua per produrre idrogeno e ossigeno gassoso, che vengono poi bruciati in un propulsore bipropellente per produrre spinta. È stata intrapresa una revisione completa della letteratura ed è stata identificata la necessità di modellare numericamente il sistema WEP (Water Electrolysis Propulsion). Il processo di progettazione concettuale del sistema è stato suddiviso principalmente in 2 parti: la prima consisteva nello sviluppare un modello MATLAB®-Simulink® dell'intero sistema e la seconda consisteva nell'utilizzare il modello Simulink® per l'ottimizzazione basata su modello per ottenere un 1 N spinta e impulso specifico più alto possibile. Il sistema WEP è stato modellato matematicamente in Simulink® come un sistema alimentato a pressione che è stato testato con alcune scelte progettuali tratte dalla letteratura. Il modello è stato trovato per simulare con successo il funzionamento del sistema. La pressione della camera, la portata massica del propellente e i semiangoli del cono della sezione convergente e divergente dell'ugello sono stati scelti come variabili di progetto per minimizzare la funzione di costo (una funzione della spinta e dell'impulso specifico). L'algoritmo genetico è stato selezionato per l'ottimizzazione e sono stati raggiunti una spinta media di 1 N e un ottimo impulso specifico di 338,9 secondi, con solo 0,38 g di propellente per sparo. Inoltre, il sistema WEP ha riportato un rapporto impulso totale/potenza (TI/P) di 1,19 N-s/W. Le variabili di progettazione sono state quindi utilizzate per dimensionare l'intero sistema, che si adatta a un volume di 2U, ideale per un CubeSat da 6U o più grande. In futuro, questo modello numerico dell'intero sistema potrà essere utilizzato così com'è, per progettare concettualmente un sistema WEP. La modellazione del sistema potrebbe essere resa più realistica considerando il gas reale invece del gas ideale e considerando anche gli effetti a gravità zero dello spazio esterno.
Design, optimization and sizing of a Water Electrolysis Propulsion (WEP) system for CubeSats
Chivukula, Varun
2021/2022
Abstract
The present work focused on the upcoming technology of using water electrolysis to produce hydrogen and oxygen gas, which then are combusted in a bipropellant thruster to produce thrust. A comprehensive literature review was undertaken and the need for numerically modelling the Water Electrolysis Propulsion (WEP) system was identified. The process of conceptually designing the system was split mainly into 2 parts – the first was to develop a MATLAB®-Simulink® model of the entire system and the second was to use the Simulink® model for model-based optimization to achieve a 1 N thrust and highest possible specific impulse. The WEP system was mathematically modelled in Simulink® as a pressure-fed system which was tested with a few design choices taken from literature. The model was found to successfully simulate the working of the system. Chamber pressure, mass flow rate of propellant and cone half angle(s) of convergent and divergent section of nozzle were chosen as the design variables to minimize the cost function (a function of thrust and specific impulse). Genetic Algorithm was selected for the optimization and an average thrust of 1 N and a very good specific impulse of 338.9 seconds, with just 0.38 g of propellant per fire, were achieved. Also, the WEP system reported a Total-impulse-to-power ratio (TI/P) of 1.19 N-s/W. The design variables were then used to size the entire system, which fit in a 2U volume, ideal for a 6U or a bigger CubeSat. In the future, this numerical model of the entire system can be used as it is, to conceptually design a WEP system. Modelling of the system could be made more realistic by considering real gas instead of ideal gas and also considering zero-g effects of the outer space.| File | Dimensione | Formato | |
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2022_12_Chivukula.pdf
Open Access dal 01/12/2023
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https://hdl.handle.net/10589/196824