Hot Helium Infusion for Methane Rocket Specific Impulse

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Solution Overview

Problem

Liquid methane/liquid oxygen rocket engines have lower specific impulse performance compared to liquid hydrogen/liquid oxygen engines, and existing methods for enhancing specific impulse are limited by undesirable properties of hydrogen, such as low temperatures and dissociation in the combustion chamber, which also make it unsuitable for propellant pumping.

Innovation Solution

Incorporating hot helium gas as a diluent into the combustion chamber with liquid methane and liquid oxygen propellants, where the helium is heated in a regenerative cooling system before injection, enhancing specific impulse by reducing molecular mass and avoiding dissociation issues, and using helium as a sole pressurizing agent for propellant pumping.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If liquid hydrogen is used to enhance specific impulse, then specific impulse increases, but tanking properties deteriorate due to extremely low temperatures and densities

Engineering Contradiction:

Improvespecific impulseVSAvoidtanking properties

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent changes the physical state parameter of the propellant from liquid hydrogen to gaseous helium, and changes the temperature parameter from cryogenic to ambient, thereby improving tanking properties while maintaining specific impulse enhancement through molecular mass reduction

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses inert helium gas instead of reactive hydrogen, eliminating chemical reaction risks in the combustion chamber and improving system reliability through the inert properties of helium

Inventive Principle:

Principle #39Inert atmosphere (Inert environment)

2Quantity of substance

If liquid hydrogen is injected into the combustion chamber, then specific impulse increases, but chemical reactions and dissociation occur

Engineering Contradiction:

Improvespecific impulseVSAvoiddissociation and chemical reactions

Core Design Contradiction:

Quantity of substanceVSObject-generated harmful factors

Solution Approach 1:

The patent introduces inert helium gas into the combustion chamber to reduce the molecular mass of exhaust gases without causing dissociation or harmful chemical reactions, as helium is chemically inert and does not undergo combustion or dissociation like hydrogen

Inventive Principle:

Principle #39Inert atmosphere (Inert environment)

3Quantity of substance

If hydrogen gas is used as propellant, then specific impulse increases, but it is unsuitable for propellant pumping

Engineering Contradiction:

Improvespecific impulseVSAvoidpropellant pumping

Core Design Contradiction:

Quantity of substanceVSEase of operation

Solution Approach 1:

The patent uses compressed helium gas pressure to pump liquid methane and liquid oxygen propellants through the engine system, replacing complex turbopump mechanisms with a simpler pneumatic pressure-driven flow system

Inventive Principle:

Principle #29Pneumatics and hydraulics

4Reliability

If methane/oxygen propellants are used, then tanking properties improve, but specific impulse performance decreases compared to hydrogen/oxygen

Engineering Contradiction:

Improvetanking propertiesVSAvoidspecific impulse performance

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent creates a composite propellant system by combining methane/oxygen chemical combustion with helium gas injection, where helium acts as a molecular mass-reducing additive that enhances specific impulse while maintaining the favorable tanking properties of methane/oxygen propellants

Inventive Principle:

Principle #40Composite materials

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach increases specific impulse and payload capability of rocket engines, simplifies hardware, and enhances reliability by eliminating the need for turbopumps, while being cost-effective due to the robust storage and inert properties of helium.

Implementation Method 1

a pressurized helium gas connected to a heat exchanger system surrounding the combustion chamber and a nozzle of the rocket engine; the heat exchanger system connected to a helium infusion control valve, the heat exchanger system configured to heat the helium gas

Methodology Applied

Scientific EffectHeat exchanger: Heat Exchanger

Implementation Method 2

the helium gas is heated in the heat exchanger system surrounding the combustion chamber and a nozzle

Methodology Applied

Scientific EffectRegenerative cooling: Heat Exchanger

Data Source

PatentUS10605204B2Methane/oxygen rocket engine with specific impulse enhancement by hot helium infusion

Publication Date: 2020.03.31 THE GOVERNMENT OF THE UNITED STATES OF AMERICA AS REPRESENTED BY THE SECRETARY DEPARTMENT OF HEALTH & HUMAN SERVICES

AI summary

An apparatus and method to enhance the performance of rockets engines which utilize liquid methane/oxygen propellants by injecting optimized amounts of pressurized hot helium gas into the combustion chamber with the propellants. In one embodiment, the pressurized helium gas is stored at low temperatures near those of the cryogenic propellants and is used for regenerative cooling of the combustion chamber and nozzle during rocket operation in order to raise the temperature of the helium gas before being injected into the combustion chamber.