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Title: Characterization & analysis on electrolytic decomposition of hydroxylammonium nitrate (HAN) ternary mixtures in microreactors
Author: Chai, Wai Siong
ISNI:       0000 0004 6425 7948
Awarding Body: University of Nottingham
Current Institution: University of Nottingham
Date of Award: 2017
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Rapid development of micropropulsion systems arose from growing interest on micro- and nanosatellites. Utilization of liquid energetic materials such as hydrazine and hydrogen peroxide as propellant in propulsion yielded promising results. However, safety issue remains a great concern as hydrazine is highly toxic. This drives the development of propellants towards lower toxicity and more environmental friendly, namely green propellants. Hydroxylammonium nitrate (HAN) was selected among three green propellants due to its high energy density in addition to ease in storage and handling properties. In order to understand the effect of addition of fuel into HAN binary solution, electrolytic decomposition of zero oxygen balance HAN ternary mixture in thermal isolated beaker was performed at macroscale. Addition of a fuel to binary HAN solution generally has more stages of decomposition, as opposed to single stage in binary HAN solution. Rate of temperature increase in the first stage of decomposition (Ṫ1) was found to be directly proportional to electrical resistivity of the HAN ternary mixture, while maximum electrolytic decomposition temperature (Tmax) of HAN ternary mixture obtained was dependent on fuel added. Visualization of HAN decomposition was demonstrated using transparent PDMS microreactors. A novel DPST integration in triggering the power supply and high speed camera was proposed. Such integration greatly reduced the cost of using a DAQ system, and was shown to capture the decomposition successfully at 5000 fps. Parametric optimization was also carried out in PDMS microreactors. Usage of 3 pairs of electrodes has increased overall reaction rate as high as 225 %, as compared to 1 pair counterpart. The overall reaction rate is proportional to flowrate and applied voltage. 3 pairs of electrodes can initiate decomposition in low voltage region. Applied voltage is the most significant parameter affecting the overall reaction rate. HAN-dextrose has lower decomposition performance compared to binary HAN solution in PDMS microreactor, using the optimized parameters carried out on binary HAN solution. This work has demonstrated both effect of fuel addition in binary HAN solution and parametric optimization in binary HAN solution towards their decomposition phenomena at macroscale and microscale,respectively. Several recommendations were made in future work section, including using screen-printing technology on the microreactor and adding a catalytic reactor after HAN was electrolyzed, to further improve decomposition efficiency.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: TP Chemical technology