Linear burn rate of green ionic liquid multimode monopropellant

Abstract

Multimode space propulsion systems are being proposed that integrate high specific impulse electric propulsion and high thrust chemical propulsion. The most important attribute of this concept is a shared propellant capable of both modes of propulsion, which enables mission flexibility. One promising approach is a catalytic monopropellant thruster paired with an electrospray electric thruster. Previous research has identified a green double-salt ionic liquid consisting of 41% wt. 1-ethyl-3-methylimidazolium ethyl sulfate and 59% wt. hydroxylammonium nitrate as a promising propellant candidate. In this work, the burn rate of this monopropellant is measured through pressure-based and high-speed imaging methods in a fixedvolume chamber pressurized across a pressure range from 0.5 to 10 MPa. Its performance is benchmarked by 80% wt. hydroxylammonium nitrate-water and nitromethane propellants. The burn rate of the multimode monopropellant is found to follow an exponential law given by = 5.35 1.11 between 0.5 and 3 MPa and is approximately constant at 142 ± 29 mm/s between 3 and 10 MPa. This work was published during the AIAA Propulsion and Energy 2019 Forum:

Catalytic Decomposition and Burning of a Dual-Mode Ionic Liquid Propellant

“…These trends of variation have good agreement with previous reports, where the ionic liquid propellant reacted on the catalytic metallic surfaces. 16 When the mass ratio of the catalyst and propellant is above 4.2, TG curves almost remain the same when the amount of catalyst further increases, indicating the saturation of the catalytic effects with limited contact areas. This condition corresponds to a practical catalytic bed where the catalyst particles are packed densely, and the catalyst has a relatively large specific surface area.…”

“…Thus, it can be supposed that the catalyst mainly affects the decomposition of HAN, and the reaction of [Emim]­[EtSO 4 ] begins at the end of HAN decomposition. These trends of variation have good agreement with previous reports, where the ionic liquid propellant reacted on the catalytic metallic surfaces . When the mass ratio of the catalyst and propellant is above 4.2, TG curves almost remain the same when the amount of catalyst further increases, indicating the saturation of the catalytic effects with limited contact areas.…”

“…The electric-mode performance of the propellant was tested in a 100 μm capillary emitter . The thermal and catalytic reaction characteristics were tested in a microreactor and on heated metallic surfaces. , The burning rate at high pressure was measured through high-speed imaging in a fixed-volume pressurized reactor . Different from hypergolic ionic liquids, − the monopropellant is generally ignited through a preheated catalytic bed installed in a thruster. , However, the ignition and combustion characteristics of the propellant in a catalytic bed are seldom reported.…”

“…14,15 The burning rate at high pressure was measured through high-speed imaging in a fixed-volume pressurized reactor. 16 Different from hypergolic ionic liquids, 17−20 the monopropellant is generally ignited through a preheated catalytic bed installed in a thruster. 21,22 However, the ignition and combustion characteristics of the propellant in a catalytic bed are seldom reported.…”

Experimental Study on Thermal and Catalytic Decomposition of a Dual-Mode Ionic Liquid Propellant

“…Mundahl and Rasmont measured the linear burning rate of HAN/[Emim][EtSO4] ionic liquid propellant, and found that the linear burning rate was strongly related to environmental pressure. At lower pressure range(0.5~3MPa), the linear burning rate increased almost linearly with the increase of pressure.And at higher pressure range(3~10MPa), the increase rate slowed down significantly [14,15]. In China, Dalian Institute of Chemical Physics studied the formulation of HAN/[Emim][EtSO4] ionic liquid propellant.…”