Study of The Heterogeneous Catalysis Enhancement of The Hypergolic Effect in W2/H2O2 Cyclonic Injector Design

Abstract

SUMMARY The combination of hydrogen peroxide and W2 which uses kerosene as a substrate to add manganese acetate as a homogeneous phase catalyst is a promising bipropellant because of its high propulsive performance low cost low toxicity and hypergolic characteristics The liquid cyclonic injector has the characteristics of simple structure and can more restrict the gas phase reaction space thereby reducing heat dissipation collecting heat energy and then igniting itself In order to improve the ignition delay and stability of the liquid cyclonic injector the hydrogen peroxide can be decomposed more rapidly by plating the surface catalyst on the reaction wall Besides to stably adhere the heterogeneous catalysts (silver silver oxide platinum manganese dioxide dimanganese trioxide and trimanganese tetraoxide) to the reaction wall the study develops its own sintering procedure This study designs two experiments including drop test and decomposition rate measurement to test the activity of hydrogen peroxide and different heterogeneous catalysts From the results of two experiments it is known that the activity of silver oxide is the best and manganese dioxide is the second In this study silver oxide and manganese dioxide catalysts are actually applied to the reaction wall and conduct a heat-fire experiment to analyze the ignition delay of the heterogeneous catalyst injector and compare the ignition delay with the non-phase-contact catalyst injector It is known from the results that the ignition delay of the heterogeneous catalyst injector gradually reduces to 0 3 seconds to 0 4 seconds and tends to be stable After comparison with the non-phase-contact catalyst injector it was found that the heterogeneous catalyst injector can gradually reduce the ignition delay time and can be more stable INTRODUCTION In 2015 I-Hsuan She used a kerosene as subtrate and used manganese acetate as a hydrogen peroxide catalyst to formulate fuel namely W2 which had a density of 0 81 g/cm^3 and a calorific value of about 32 3 KJ/g The ignition time of W2 and high concentration hydrogen peroxide was about 20 ms (24 degrees Celsius O/F = 0 8) For reducing the ignition delay time of W2 and hydrogen peroxide propellant combination an injection mechanism had been developed which was named liquid cyclonic injector The concept of the liquid cyclonic injector is that the fuel and the oxidant are injected into the small cylindrical chamber at a high flow rate for spiral movement so that the propellants can be rapidly mixed and the contact time is increased to promote the reaction heat release Ignition occurs when the gas-phase temperature reaches its auto-ignition point Jyun-Ci Guo used W2/hydrogen peroxide as propellants and used a liquid cyclonic injector for ignition experiments and further studied its geometry and operating conditions It was found that if the liquid cyclonic injector was designed to have a cavity diameter of 10 mm and injection orifice of 0 3mm a shorter and stable ignition delay time could be obtained under the operating conditions of O/F=4 and total mass flow rate of 6 g/s to 7 g/s Also Jyun-Ci Guo observed the combustion products attached on wall of injector could promote the decomposition of hydrogen peroxide and the heat release rate so that the shorter ignition delay and wider ignition range were observed EXPERIMENTAL METHODS This research is divided into three parts the first one is to sinter manganese oxide on the surface named manganese oxide preparation And the second is drop test and decomposition rate measurement to understand the activity of hydrogen peroxide for different heterogeneous catalysts Finally the best activity of heterogeneous catalysts would be applied to the liquid cyclonic injector and used in the hot-fire experiment which ignition delay and ignition stability are discussed RESULTS AND DISCCUSION In the results of manganese oxide preparation it is found that after detection of manganese dioxide (Fig 21) 35 5% are Pyrolusite-MnO2 and 17 6% of Ramsdellite-MnO2 The difference between the two is in the crystal structure Also the test results show that the manganese trioxide (Fig 22) and trimanganese tetraoxide (Fig 23) is 100% pure substance The heterogeneous catalyst manganese dioxide dimanganese trioxide trimanganese tetraoxide silver silver oxide and platinum are done the activity tests with hydrogen peroxide And tests can be divided into two types The first one is a drop test in which 95% of hydrogen peroxide droplets (average 0 027 g/drop) are dropped on heterogeneous catalysts The reaction time for decomposition of hydrogen peroxide and the reaction process defined by decomposition are tested The second type is the decomposition rate measurement by placing a stainless-steel plate with a heterogeneous catalyst into an Erlenmeyer flask containing 20% and 20 ml by volume of hydrogen peroxide The pressure generated by the releasing in oxygen is measured From this different heterogeneous catalysts react with hydrogen peroxide under long-term changes can be observed From the results of the drop test (Fig 30) the activity of hydrogen peroxide on different heterogeneous catalysts is AgO>MnO2>Mn2O3>Mn3O4>Ag>Pt From the decomposition rate measurement results (Fig 35) the activity of hydrogen peroxide on different heterogeneous catalysts is AgO>MnO2>Mn2O3>Mn3O4 Above two results are compatible In this experiment the active silver oxide and manganese dioxide in the heterogeneous catalyst are best so they are selected for the liquid cyclonic injector to carry out the hot-fire experiment and the ignition delay time was analyzed In the hot-fire experiment when comparing the average values of the first ignition delay times of two heterogeneous catalysts (Table 22 and Table 23) it is observed that the manganese dioxide catalyst injector is slightly faster than the silver oxide catalyst In the subsequent ignition experiment it is presumed that a large amount of manganese oxide transformed from manganese acetate in the high temperature is attached to the surface catalyst so that the ignition delay tends to be reduced continuously This trend tends to be stable from about 0 3 seconds to 0 4 seconds Compare the ignition delay of the heterogeneous catalyst injector and the injector without the heterogeneous catalyst (Table 24) regardless of whether the non-phase catalyst injector is clean or not there is a significant jitter at the ignition delay and there are half the number of ignition failures It can be seen that the liquid cyclonic injector with the heterogeneous catalyst can gradually reduce the ignition delay and can be more stable CONCLUSION After multiple ignitions of the heterogeneous catalyst injector the surface of the heterogeneous catalyst is heavily attached by manganese oxide which contributes to the reduction of the ignition delay and tends to stabilize from 0 3 seconds to 0 4 seconds but the experimental results show that the ignition delay cannot be effectively reduced only 5%-9% can be shortened but the stability of the ignition delay time would be increase ?

Date of Award	2019
Original language	English
Supervisor	Hsiao-Feng Yuan (Supervisor)