With the boom of space activities in recent years and the increasing concern for clean technologies, green space propulsion is becoming a topic of interest within the space sector. Unfortunately, most of the propellants used for space activities tend to be highly toxic, corrosives, and even carcinogenic. Toxicity is especially critical for the hypergolics, which in most cases are the preferred propellant due to their simple application as they ignite upon contact. Throughout the history of space propulsion, some chemicals have been left aside due to their low performance when benchmarked against these more powerful hypergolic propellants. However, the trend of "green'' technologies is pushing research towards green lower performance propellants. This is the case of hydrogen peroxide, H2O2, which was left aside due to its reduced effectiveness and the complexity to exploit its energy. Nonetheless, the work with hydrogen peroxide has recently acquired a new focus. Its green perspective has instigated large projects by the European Commission, such as GRASP, and approaches to exploit its energetic content are a topic of research. Currently, the use of catalysts to decompose the chemical is the usual procedure. However, their complexity and effect on performance raise some problems. In this thesis, a new approach through thermal energy supply aims at avoiding the catalyst approach to decompose hydrogen peroxide and overcome their related problems. The feasibility of this approach is tested and characterized for different combinations of temperatures and concentrations of hydrogen peroxide. In order to characterize this, a first look into the procurement of the chemical is done. The different approaches presented lead to a successful refining technique, which is now patented. This innovative approach allows acquiring hydrogen peroxide in concentrations in excess of 99% in the span of 1-2 days for a reduced price. The simplicity of this technique is unrivaled to the stringent regulations surrounding its commercial availability. The resulting solution is investigated in terms of stability over time and concentration. The final selected concentrations for this study are 75, 80, 85, 90, and 95% H2O2. The thermal activation of hydrogen peroxide is first investigated. Through an open-air drop-test study, the droplets of H2O2 are generated and precipitated over a heating plate at various temperatures. The combinations of temperature and concentration, which lead to decomposition, are recorded and analyzed through a set of thermocouples and a high-speed camera at 6400 fps. For the valid combinations, the analysis returns their maximum temperatures and decomposition delay times. Values of up to 800 celsius for 90 and 95% H2O2 are achieved, and low decomposition delay times below 100 ms were measured for heating plate temperatures of 250 and 270 celsius. This information is put against the decomposition with catalyst MnO2 for comparison, showing a more significant temperature released for the thermal approach, but a slower decomposition. With the valid decomposition combinations, an ignition study is conducted with ethanol as the fuel and hydrogen peroxide as the oxidizer. Through a drop test on a heating plate, the mechanisms leading to the ignition are researched. The tests showed that ignition is pseudo-hypergolic and can achieve increases in temperature of up to 700 celsius for 95% H2O2 and ethanol, reaching maximum temperatures over 1000 celsius at points. The tests showed that combinations with 90 and 95% H2O2 result on average ignition delay times below 100 ms. The conducted test cases showed that the ignition temperature profiles can be correlated with the recorded filming and that the lessons learned can be applied for a future combustion chamber. In order to test performance-boosting techniques, the gelling of the fuel was done and tested. The results are promising, the ignition of ethanol with 1.8% wt. of hydroxypropyl cellulose reached such temperatures that melted a thermocouple, proving the ability to raise the performance.
Lastly, the gel sample was characterized in terms of a rheology study by performing a strain sweep to find its yield point. Moreover, a shear rate analysis was performed, and its thixotropic nature was tested through a hysteresis loop. The effect of temperature was also analyzed and fitted to an exponential Arrhenius-like form.