Ignition device, method for producing the same, ignition method and rocket combustion system
The present disclosure is directed to an ignition device including a housing, a bulk fuel, and at least two lead wires as electrodes. The bulk fuel is made of a plastic material, such as polylactic acid (PLA) or epoxy resin. The bulk fuel contains an internally dispersed powdery conductive material, thereby obtaining a conductive solid fuel. One end of the lead wire is partially embedded in the bulk fuel. The other end of the lead wire is connected to a power source. A portion of the bulk fuel is gasified by energizing the lead wire, and the gasified fuel is combusted by reaction with an oxidant.
1 . An ignition device comprising:
a conductive solid fuel as a bulk fuel including:
a plastic material, and
a powdery conductive substance dispersed in the plastic material, the conductive solid fuel being gasified by heating due to energization and ignited by a reaction with an externally supplied oxidant;
at least two electrodes partially embedded in the bulk fuel;
wherein the bulk fuel is gasified by Joule heat that is generated by an electric current passing from one of the at least two electrodes through the bulk fuel including the powdery conductive substance toward another of the at least two electrodes, and
said Joule heat is a heat generation phenomenon caused by formation of a conductive path inside the bulk fuel including the powdery conductive substance due to said energization with a voltage of 100 [V] or less and an electric power of 18 [W] or higher applied between the at least two electrodes.
2 . The ignition device according to claim 1 , wherein the bulk fuel is made of a material selected from the group consisting of polylactic acid, epoxy resin, polyethylene, polyester, polyurethane, polyacrylonitrile, polymethyl methacrylate, acrylonitrile-butadiene-styrene resin, and polyethylene terephthalate.
3 . The ignition device according to claim 1 , wherein the conductive substance is made of a material selected from the group consisting of graphite, carbon black, metal, semiconductor, graphene, carbon fiber, and carbon nanotube.
4 . The ignition device according to claim 1 , wherein the bulk fuel has a prismatic shape or a cylindrical shape, each extending along a longitudinal direction thereof.
5 . The ignition device according to claim 1 , wherein the bulk fuel has a volume resistivity of 0.763 [Ω·cm] to 10,000,000 [Ω·cm].
6 . The ignition device according to claim 1 , wherein an electrode terminal having a shape of fork, mesh, rod or hollow cylinder is attached to an leading end of each of the electrodes.
7 . An ignition method using the ignition device according to claim 1 including steps of:
gasifying a part of the bulk fuel by using heat generated by energization between the electrodes; and
supplying an oxidant to combust the gasified bulk fuel.
8 . A rocket combustion system comprising:
an oxidant line for feeding an oxidant;
a flow rate valve for controlling a flow rate of the oxidant flowing through the oxidant line;
a casing having an internal space to which the oxidant line is connected;
a main fuel stored in the internal space;
a nozzle for discharging a combustion gas generated by a reaction between the main fuel and the oxidant; and
the ignition device according to claim 1 , provided between the oxidant line and the internal space to ignite the main fuel.
9 . A method for producing an ignition device according to claim 1 , including steps of:
softening a conductive solid fuel including a bulk fuel made of a plastic material and a powdery conductive substance dispersed in the bulk fuel, by heating;
press-fitting and partially embedding at least two electrodes into the softened conductive solid fuel; and
fixing the electrodes by curing the conductive solid fuel.
10 . A method for producing an ignition device, comprising:
softening a conductive solid fuel including a bulk fuel made of a plastic material and a powdery conductive substance dispersed in the bulk fuel, by heating;
press-fitting and partially embedding at least two electrodes into the softened conductive solid fuel; and
fixing the at least two electrodes by curing the conductive solid fuel.
11 . The method according to claim 10 , wherein the bulk fuel comprises a material selected from the group consisting of polylactic acid, epoxy resin, polyethylene, polyester, polyurethane, polyacrylonitrile, polymethyl methacrylate, acrylonitrile-butadiene-styrene resin, and polyethylene terephthalate.
12 . The method according to claim 10 , wherein the conductive substance comprises a material selected from the group consisting of graphite, carbon black, metal, semiconductor, graphene, carbon fiber, and carbon nanotube.
13 . The method according to claim 10 , wherein the bulk fuel has a prismatic shape or a cylindrical shape, each extending along a longitudinal direction thereof.
14 . The method according to claim 10 , wherein the bulk fuel has a volume resistivity of 0.763 [Ω·cm] to 10,000,000 [Ω·cm].
15 . The method according to claim 10 , wherein the bulk fuel is gasified by Joule heat that is generated by an electric current passing from one of the at least two electrodes through the bulk fuel including the powdery conductive substance toward another of the at least two electrodes, and the Joule heat is a heat generation phenomenon caused by formation of a conductive path inside the bulk fuel including the powdery conductive substance due to energization with a voltage of 100 [V] or less and an electric power of 18 [W] or higher applied between the at least two electrodes.