Method for Determining Reaction Equation and Combustion Heat of Aluminum-Containing Hydrogen Peroxide Gel Propellant

Abstract

The present invention belongs to the field of aerospace technology and discloses a method for determining the reaction equation and combustion heat of aluminum-containing hydroperoxide gel propellant. The method utilizes a closed combustion experiment to determine the primary chemical reaction equations, the proportions of the various reaction components, and the combustion heat of the aluminum-containing hydroperoxide gel propellant. This method quantitatively determines the reaction process, features a simple experimental method, and is highly operational. It addresses the issue of unclear combustion reaction equations and reaction heats for aluminum-containing hydroperoxide gel propellants, provides a reference for the research of new propellants and the development and design of engines, and facilitates engineering applications.

Description

Technical Field

[0001] The invention belongs to the field of aerospace technology and relates to a method for determining a combustion reaction equation and combustion heat of a metallized gel propellant, in particular to a method for determining a reaction equation and combustion heat of an aluminum-containing hydrogen peroxide gel propellant. Background Art

[0002] In rocket engines, the use of gel propellants can simplify propellant supply piping systems, while the addition of metal powders to gel oxidizers can create high-energy monopropellants, which have great development potential. Currently, the addition of aluminum powder to gel hydrogen peroxide is a new form of high-energy monopropellant. Because pure hydrogen peroxide is a liquid oxidizer containing hydrogen and oxygen, its decomposition products are water vapor and oxygen. It can be used as both an oxidizer and a monopropellant. However, due to its low effective oxygen content, its application in rocket engines is not widespread. Aluminum powder, on the other hand, is often used to increase propellant energy due to its high density, high combustion enthalpy, and the fact that the solid metal oxide particles produced by combustion can suppress combustion oscillations. In addition, the patent document published by He Zhicheng and others from the National University of Defense Technology (He Zhicheng, Zhou Xing. A hydrogen peroxide gel propellant containing metal fuel and its preparation method: ZL202111592362.0[P].2022-03-18) pointed out that aluminum powder and gel hydrogen peroxide have good compatibility and the gel system is relatively stable; from theoretical calculations, aluminum powder will also react with water; therefore, the hydrogen peroxide gel propellant containing aluminum powder has high energy and is a new type of single-component propellant with potential application prospects.

[0003] As a new type of propellant, the combustion reaction equation and reaction heat of aluminum-containing hydroperoxide gel propellant are still unclear. Theoretically, its combustion process may include the following reactions: (1) Hydrogen peroxide decomposes under heat to produce water vapor and oxygen; (2) Aluminum powder reacts with oxygen to produce aluminum oxide; (3) Aluminum powder and water react at a low reaction temperature to produce aluminum hydroxide and hydrogen; (4) Aluminum powder and water react at a high temperature to produce aluminum oxide and hydrogen; (5) Hydrogen and oxygen react to produce water vapor. However, there is currently no solution to how to determine the amount of substances in the above reaction processes, and the combustion heat of aluminum-containing hydroperoxide gel is also unclear. Summary of the Invention

[0004] Aiming at the combustion reaction process of aluminum-containing hydroperoxide gel propellant, the present invention proposes a method for determining the main chemical reaction equations and the proportions of each reaction component in this type of propellant by using a closed combustion experiment, and clarifies the combustion heat of the aluminum-containing hydroperoxide gel propellant.

[0005] The technical solution of the present invention:

[0006] A method for determining the reaction equation and combustion heat of aluminum-containing hydrogen peroxide gel propellant comprises the following steps:

[0007] (1) A sample of aluminum-containing hydrogen peroxide gel propellant (containing aluminum powder a1 g, hydrogen peroxide a2 g, wherein the hydrogen peroxide is in excess and no residue remains after a full reaction) is placed in a closed burner (volume YL) equipped with a pressure sensor and a temperature sensor, the propellant is ignited, and the pressure-time curve and temperature-time curve in the burner are recorded; after the experiment, the mass of the solid remaining in the burner is weighed, and the material composition and mass of the residual solid after the reaction are determined. It is determined by detection that the residual solid contains aluminum oxide and aluminum hydroxide. The mass of aluminum oxide is irrelevant to the establishment and solution of the equation, so it does not need to be measured. The mass of aluminum hydroxide is a3 g;

[0008] (2) According to the pressure-time curve and temperature-time curve, the maximum pressure during the reaction is a4 Pa and the maximum temperature is a5 K. After the closed burner is cooled, the water vapor condenses into liquid water, and at this time the pressure-time curve will drop sharply. The pressure after the steep drop is recorded as a6 Pa and the temperature is a7 K.

[0009] (3) The combustion process may include the following reactions: hydrogen peroxide decomposes under heat in the burner: ①H2O2=H2O+0.5O2; aluminum powder and water react at a lower temperature to form aluminum hydroxide: ②Al+3H2O=Al(OH)3+1.5H2; aluminum powder and water react at a high temperature to form aluminum oxide: ③Al+1.5H2O=0.5Al2O3+1.5H2; aluminum powder and oxygen react to form aluminum oxide: ④Al+0.75O2=0.5Al2O3; hydrogen and oxygen react to form water vapor: ⑤H2+0.5O2=H2O;

[0010] (4) According to the chemical equation ①, the amount of oxygen and water vapor generated by the decomposition of hydrogen peroxide (a2 g) can be determined; according to the mass of aluminum hydroxide in the combustion reaction product being a3 g, the amount of the substance in the reaction equation of aluminum powder and water at a lower temperature in equation ② can be determined; assuming that the mass of aluminum powder involved in equation ③ is X1 g, the mass of aluminum powder involved in equation ④ is X2 g, and the mass of hydrogen involved in equation ⑤ is X3 g, then there are three unknown parameters X1, X2, and X3 in the combustion reaction, and three equations need to be listed to solve;

[0011] (5) According to the ideal gas state equation (n = pV / RT), the amount of gas contained in the closed burner in two states (after full reaction and cooling) can be calculated respectively;

[0012] (6) The first equation is obtained based on the conservation of mass of aluminum powder before and after the combustion reaction. That is, the mass of aluminum powder participating in the reaction is the sum of the mass of aluminum powder reacting with oxygen, the mass of aluminum powder reacting with water to form aluminum hydroxide, and the mass of aluminum powder reacting with water to form aluminum oxide.

[0013] (7) The second equation can be established based on the difference in the amount of gas contained in the closed burner under the two conditions determined by the maximum pressure and temperature during the combustion reaction and the pressure and temperature after cooling, that is, the amount of water vapor in the closed burner (the amount of water generated by the decomposition of hydrogen peroxide minus the amount of water consumed by aluminum powder, plus the amount of water generated by the reaction of hydrogen and oxygen);

[0014] (8) The third equation can be established based on the relationship between the temperature rise in the closed burner before and after the combustion reaction and the reaction heat: ΔT = Q / c p , where c p Indicates the constant pressure specific heat capacity of each substance. Here, it is necessary to calculate the constant pressure specific heat of all substances participating in the chemical reaction. This value varies greatly with temperature, so the constant pressure specific heat value at the average temperature is taken here;

[0015] (9) Solve the three unknowns in step (4) according to the three equations listed in steps (6)(7)(8) to determine the amount of each substance in the chemical reaction equations ①, ②, ③, ④, and ⑤;

[0016] (10) Based on the reaction heat of each reaction equation and the amount of reactants in each reaction equation determined in step (9), the total combustion heat of the combustion reaction of the aluminum-containing hydrogen peroxide gel propellant is calculated.

[0017] The present invention provides the following benefits: a simple determination method, easy to operate and process; a clear calculation process, and the ability to clearly determine the chemical reaction equations likely involved in the burner; and a method for quantitatively determining the specific equation for the combustion reaction of aluminum powder and hydrogen peroxide, thereby determining the combustion heat of aluminum-containing hydrogen peroxide gel propellant. This invention addresses the issue of unclear combustion reaction equations and reaction heats for aluminum-containing hydrogen peroxide gel propellants, provides a reference for the research of new propellants and the development and design of engines, and facilitates engineering applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 1 is a pressure-time curve in a closed combustor recorded by a pressure sensor in an embodiment.

[0019] Figure 2 : is the temperature-time curve in the closed burner recorded by the temperature sensor in the embodiment. DETAILED DESCRIPTION

[0020] The specific implementation of the present invention is described in detail below in conjunction with the technical solution.

[0021] Example: Determine the combustion reaction equation and reaction heat of 0.47g of aluminum-containing hydrogen peroxide gel propellant.

[0022] (1) A sample of aluminum-containing hydrogen peroxide gel propellant (containing 0.13 g of aluminum powder and 0.34 g of hydrogen peroxide) was placed in a closed burner (volume of 2 L) equipped with a pressure sensor and a temperature sensor. The propellant was ignited, and the pressure-time curve and temperature-time curve in the burner were recorded. After the experiment, the mass of the solid remaining in the burner was weighed, and the material composition and mass of the residual solid after the reaction were determined. The mass of aluminum oxide and aluminum hydroxide in the residual solid was determined by detection (0 g). The mass of aluminum powder participating in the combustion reaction was 0.13 g. Among them, the pressure-time curve in the closed burner recorded by the pressure sensor is as follows: Figure 1 As shown in the figure: the maximum pressure value is 660689.6625Pa (corresponding to 1s); the pressure after shaking is 101325Pa (corresponding to 100s); the temperature-time curve in the closed burner recorded by the temperature sensor is as follows Figure 2 As shown in the figure: the maximum temperature value is 1737K (corresponding to the time of 2.2s); the temperature after cooling is 300K (corresponding to the time of 100s).

[0023] (2) According to the pressure-time curve and temperature-time curve, the maximum pressure of the reaction process is 660689.6625 Pa and the maximum temperature is 1737 K. After the closed burner is cooled, the water vapor condenses into liquid water. At this time, the pressure-time curve will drop sharply. The pressure after the steep drop is recorded as 101325 Pa and the temperature is 300 K.

[0024] (3) The combustion process may include the following reactions: hydrogen peroxide decomposes under heat in the burner: ①H2O2=H2O+0.5O2; aluminum powder and water react at a lower temperature to form aluminum hydroxide: ②Al+3H2O=Al(OH)3+1.5H2; aluminum powder and water react at a high temperature to form aluminum oxide: ③Al+1.5H2O=0.5Al2O3+1.5H2; aluminum powder and oxygen react to form aluminum oxide: ④Al+0.75O2=0.5Al2O3; hydrogen and oxygen react to form water vapor: ⑤H2+0.5O2=H2O;

[0025] (4) According to the chemical equation ①, it can be determined that hydrogen peroxide (0.34g) decomposes to generate 0.16g of oxygen and 0.18g of water vapor, wherein the amount of water vapor is 0.01mol; according to the mass of aluminum hydroxide in the combustion reaction product being 0g, it can be determined that the mass of aluminum powder participating in the reaction in the equation ② is 0g; assuming that the mass of aluminum powder participating in the equation ③ is X1g, the amount of water consumed in the reaction is X1 / 18g; assuming that the mass of aluminum powder participating in the equation ④ is X2g; assuming that the mass of hydrogen participating in the equation ⑤ is X3g, the amount of water generated in the reaction is X3 / 2g; there are three unknown parameters X1, X2, and X3 in the combustion reaction, which requires three equations to be solved;

[0026] (5) According to the ideal gas state equation (n = pV / RT), the amount of gas contained in the burner in the two states can be calculated as 0.0915 mol (fully reacted) and 0.0812 mol (after cooling), respectively, where the gas constant R = 8.314 J / (mol·K);

[0027] (6) The first equation is obtained based on the conservation of mass of aluminum powder before and after the combustion reaction. That is, the mass of aluminum powder participating in the reaction is the sum of the mass of aluminum powder reacting with oxygen (X2), the mass of aluminum powder reacting with water to form aluminum hydroxide (0g), and the mass of aluminum powder reacting with water to form aluminum oxide (X1), which can be expressed as: X1+0+X2=0.13;

[0028] (7) The second equation can be established based on the difference in the amount of substance of the gas contained in the burner under two conditions determined by the maximum pressure and temperature during the combustion reaction and the pressure and temperature after cooling, that is, the amount of substance of water vapor in the burner (the amount of substance of water generated by the decomposition of hydrogen peroxide minus the amount of substance of water consumed by aluminum powder, plus the amount of substance of water generated by the reaction of hydrogen and oxygen), and is expressed as: 0.01-X1 / 18+X3 / 2=0.0915-0.0812, where the left side of the equation is the amount of substance of water vapor obtained according to chemical equilibrium;

[0029] (8) The third equation can be established based on the relationship between the temperature rise in the closed burner before and after the combustion reaction (1438.85K) and the reaction heat (Q = 540.46 + 475261X1 / 27 + 833750X2 / 27 + 241826X3 / 2J): ΔT = Q / c p , where c p Indicates the constant pressure specific heat capacity of each substance. Here we need to calculate the constant pressure specific heat capacity (c p =0.71772X1+0.21878X2-4.49050X3+3.19525J / mol·K). This value varies greatly with temperature, so the constant pressure specific heat value at the average temperature is used here.

[0030] (9) Solve the three unknowns in step (4) according to the three equations listed in steps (6), (7), and (8), and obtain X1 = 0.0484g, X2 = 0.0816g, and X3 = 0.0059g. The amount of substances in the chemical reaction equations ①, ②, ③, ④, and ⑤ can be determined, namely: ①1 / 100H2O2 = 1 / 100H2O + 1 / 200O2; ②0Al + 0H2O =0Al(OH)3+0H2; ③121 / 67500Al+121 / 45000H2O=121 / 135000Al2O3+121 / 45000H2; ④ 17 / 5625Al+17 / 7500O2=17 / 11250Al2O3; ⑤59 / 20000H2+59 / 40000O2=59 / 20000H2O;

[0031] (10) Based on the reaction heat of each reaction equation and the amount of reactants in each reaction equation determined in step (9), the total combustion heat of the combustion reaction of the aluminum-containing hydrogen peroxide gel propellant is calculated to be 4625.57 J.

[0032] This example proposes a method for determining the chemical reaction equations and the proportions of the various reaction components in an aluminum-containing hydrogen peroxide gel propellant using a closed combustion experiment. The reaction equations are determined based on experimental parameter changes and quantitative chemical reaction analysis, and the combustion heat of the aluminum powder and hydrogen peroxide combustion reaction is clarified, providing a reference for the research of new propellants and the development and design of engines.

Claims

1. A method for determining the reaction equation and combustion heat of aluminum-containing hydrogen peroxide gel propellant, characterized in that: Here are the steps: (1) A sample of aluminum-containing hydrogen peroxide gel propellant is placed in a sealed burner equipped with a pressure sensor and a temperature sensor, wherein the propellant contains aluminum powder a1 g and hydrogen peroxide a2 g, and the hydrogen peroxide is in excess and no residue remains after a full reaction; the propellant is ignited, and the pressure-time curve and temperature-time curve in the burner are recorded; after the experiment, the mass of the solid remaining in the burner is weighed, and the material composition and mass of the residual solid after the reaction are determined. It is determined by detection that the residual solid contains aluminum oxide and aluminum hydroxide. The mass of aluminum oxide is irrelevant to the establishment and solution of the equation, so it does not need to be measured. The mass of aluminum hydroxide is a3 g; (2) According to the pressure-time curve and temperature-time curve, the maximum pressure during the reaction is a4 Pa and the maximum temperature is a5 K. After the closed burner is cooled, the water vapor condenses into liquid water, and at this time the pressure-time curve will drop sharply. The pressure after the steep drop is recorded as a6 Pa and the temperature is a7 K. (3) The combustion process includes the following reactions: hydrogen peroxide decomposes under heat in the burner: ①H2O2=H2O+0.5O2; aluminum powder and water react at a lower temperature to form aluminum hydroxide: ②Al+3H2O=Al(OH)3+1.5H2; aluminum powder and water react at a high temperature to form aluminum oxide: ③Al+1.5H2O=0.5Al2O3+1.5H2; aluminum powder and oxygen react to form aluminum oxide: ④Al+0.75O2=0.5Al2O3; hydrogen and oxygen react to form water vapor: ⑤H2+0.5O2=H2O; (4) Determine the amount of oxygen and water vapor generated by the decomposition of hydrogen peroxide a2 g according to the chemical equation ①; determine the amount of the reaction equation of aluminum powder and water at a lower temperature in equation ② according to the mass of aluminum hydroxide in the combustion reaction product being a3 g; assuming that the mass of aluminum powder involved in equation ③ is X1 g, the mass of aluminum powder involved in equation ④ is X2 g, and the mass of hydrogen involved in equation ⑤ is X3 g, then there are three unknown parameters X1, X2, and X3 in the combustion reaction, and three equations need to be listed and solved; (5) Calculate the amount of gas contained in the closed burner in the two states of full reaction and cooling according to the ideal gas state equation; (6) The first equation is obtained based on the conservation of mass of aluminum powder before and after the combustion reaction. That is, the mass of aluminum powder participating in the reaction is the sum of the mass of aluminum powder reacting with oxygen, the mass of aluminum powder reacting with water to form aluminum hydroxide, and the mass of aluminum powder reacting with water to form aluminum oxide. (7) The second equation is established based on the difference in the amount of gas contained in the closed burner under the two conditions determined by the maximum pressure and temperature during the combustion reaction and the pressure and temperature after cooling, that is, the amount of water vapor in the closed burner; wherein the amount of water vapor in the closed burner is the amount of water generated by the decomposition of hydrogen peroxide minus the amount of water consumed by aluminum powder, plus the amount of water generated by the reaction of hydrogen and oxygen; (8) The third equation is established based on the relationship between the temperature rise in the closed burner before and after the combustion reaction and the reaction heat: ΔT = Q / c p , where c p Indicates the constant pressure specific heat capacity of each substance. It is necessary to calculate the constant pressure specific heat of all substances participating in the chemical reaction. This value varies greatly with temperature, so the constant pressure specific heat value at the average temperature is taken. (9) Solve the three unknowns in step (4) according to the three equations listed in steps (6), (7), and (8) to determine the amount of each substance in the chemical reaction equations ①, ②, ③, ④, and ⑤; (10) Based on the reaction heat of each reaction equation and the amount of reactants in each reaction equation determined in step (9), the total combustion heat of the combustion reaction of the aluminum-containing hydrogen peroxide gel propellant is calculated.

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