Liquid propellants have a high specific impulse value and play an important role in the aerospace field.

Liquid propellant is a liquid chemical propellant and the power source of liquid rocket engines. It plays an important role in the aerospace industry. Liquid propellant can be a single liquid substance or a combination of several liquid substances. According to the number of components, liquid propellants can be divided into single-component propellants, bi-component propellants, and three-component propellants. Among them, one component of the bi-component propellant is the oxidizer, and the other component is the oxidizer. Yuan is a combustion agent. Due to its high specific impulse value and high safety, it is the current mainstream liquid propellant product type.

According to the “2021-2025 Liquid Propellant Industry In-depth Market Research and Investment Strategy Suggestions Report” released by the Industrial Research Center, both Among component propellants, common liquid oxidants mainly include liquid oxygen, liquid fluorine, nitric acid, dinitrogen tetroxide, hydrogen peroxide, chlorine trifluoride, etc.; common liquid combustion agents mainly include liquid hydrogen, ethanol, kerosene, and hydrazine. Class etc. Bicomponent propellants, as mainstream liquid propellants, need to be stored separately in liquid rocket engines and then mixed and burned when needed.

In the 1920s, the first liquid fuel rocket successfully launched by the United States used a liquid oxygen + kerosene bi-component liquid propellant; in the 1940s, the V-2 missile developed by Germany used a liquid oxygen + ethanol bi-component propellant. Liquid propellant. Generally speaking, the main factors that need to be considered when selecting liquid propellant materials are specific impulse value, combustion performance, thermal stability, thermal conductivity, property stability, unit density, storability, cost, availability, toxicity, and corrosion. Sex etc.

In the early days, liquid propellants mainly used hydrazine as the combustion agent and dinitrogen tetroxide as the oxidant. The former was highly toxic and the latter was highly corrosive, and this type of liquid propellant had a low specific impulse value. After that, liquid propellants began to use liquid oxygen as the oxidant and kerosene as the combustion agent. The specific charge value of kerosene is slightly higher than that of hydrazine, and it is non-toxic and cheap. Liquid propellants using liquid hydrogen as the combustion agent and liquid oxygen as the oxidant have the highest specific impulse value, but are large in size, high in cost, and require low-temperature storage.

Among the common materials of liquid propellant, liquid oxygen, liquid hydrogen, liquid fluorine, etc. require low-temperature storage and short storage time, while other materials can be stored for a long time. Compared with solid propellants, liquid propellants have the advantages of higher specific impulse and stronger carrying capacity. Space rockets basically use liquid propellants, and large missiles also need to use liquid propellants. However, the stability of liquid propellants is relatively poor, and some materials need to be filled before the aircraft is launched, which prolongs the launch time. Therefore, solid propellants are the mainstream product in terms of missiles.

Industry analysts said that under low temperature conditions, the actual specific charge value of liquid propellant is higher, which is especially suitable for heavy-duty launch vehicles. , against the background of the increasing number of satellite launches and the rapid development of the manned space industry, the liquid propellant market has broad prospects. Liquid rocket engines can produce reusable engines. In order to reduce launch costs, reusable liquid rocket engines have become an important research direction, which will further increase the demand for liquid propellants in the aerospace industry.