Electric Rocket Engine Cooling System with Phase Change Loop

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Solution Overview

Problem

Current electric rocket engine cooling systems are ineffective in space due to the absence of convection and heat conduction, leading to temperature regulation challenges and inefficiencies, particularly in low-pressure and low-temperature environments, and require continuous propellant replenishment and preheating for operation.

Innovation Solution

A forced cooling system with a pump, cooling jacket, working substance storage reservoir, expansion tank, thermostatic valve, radiator, and safety valve, which maintains a controlled temperature range by regulating the working substance flow and pressure, and includes preheating mechanisms to manage vaporization and condensation, ensuring continuous operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If propellant is used for cooling in electric rocket engines, then heat removal capability is improved, but the system requires continuous propellant replenishment and preheating

Engineering Contradiction:
Improveheat removal capabilityVSAvoidpropellant replenishment requirement
Core Design Contradiction:
Loss of energyVSLoss of substance

Solution Approach 1:

The cooling system uses a closed-loop design where the coolant circulates continuously through the engine components and radiator without requiring external replenishment. The system serves itself by maintaining its own cooling capacity through the phase change and circulation mechanisms, eliminating the need for continuous propellant addition

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The system utilizes phase transitions of the coolant (liquid to vapor and back) to absorb and release heat. The coolant evaporates in the engine cooling channels to absorb heat, then condenses in the radiator to release heat, creating a self-sustaining thermal management cycle that doesn't require continuous replenishment

Inventive Principle:
Principle #36Phase transitions

2Measurement precision

If forced cooling system is implemented, then temperature regulation precision is improved, but device complexity increases

Engineering Contradiction:
Improvetemperature regulation precisionVSAvoidcooling system structure
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The cooling system merges multiple functions into integrated components: the cooling channels are built into the engine structure itself, the pump is integrated with the circulation system, and the radiator is combined with the coolant storage and phase change mechanisms. This reduces overall system complexity while maintaining precise temperature control

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The system incorporates feedback mechanisms through thermostatic valves and temperature sensors that automatically adjust coolant flow and radiator operation based on real-time temperature conditions, enabling precise temperature regulation without complex control systems

Inventive Principle:
Principle #23Feedback

3Loss of energy

If propellant evaporates to cool the engine, then cooling effectiveness is improved, but internal pressure increases sharply

Engineering Contradiction:
Improvecooling effectivenessVSAvoidinternal pressure
Core Design Contradiction:
Loss of energyVSStress or pressure

Solution Approach 1:

The system extracts the vapor phase from the closed cooling loop and directs it to the radiator where it condenses back to liquid. This prevents pressure buildup by continuously removing vapor and converting it back to liquid form, maintaining safe operating pressures while preserving cooling effectiveness

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The system dynamically adjusts the balance between evaporation and condensation based on thermal load conditions. The thermostatic valves and pump control the rate of phase change and coolant circulation, allowing the system to adapt to varying heat generation while maintaining pressure within safe limits

Inventive Principle:
Principle #15Dynamics

4Reliability

If cooling system operates in space vacuum, then thermal insulation is improved, but heat dissipation capability worsens

Engineering Contradiction:
Improvethermal insulationVSAvoidheat dissipation capability
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The system replaces convection-based heat dissipation (which requires atmospheric gases) with phase change-based heat transfer. The coolant evaporates and condenses in a controlled manner, transferring heat efficiently without relying on convective heat transfer to the surrounding vacuum environment

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system utilizes phase transitions of the coolant (liquid to vapor and back) to absorb and release heat. The coolant evaporates in the engine cooling channels to absorb heat, then condenses in the radiator to release heat, creating a self-sustaining thermal management cycle that doesn't require continuous replenishment

Inventive Principle:
Principle #36Phase transitions

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

The system effectively regulates the temperature of electric rocket engine components, preventing overheating and overcooling, maintaining operational efficiency, and allowing for continuous operation without the need for continuous propellant replenishment or preheating, by using a controlled working substance flow and pressure management.

Implementation Method 1

a power unit - a pump 1 providing continuous working substance flow in the cooling system without cavitation developing

Methodology Applied
Scientific EffectPump: Pump

Implementation Method 2

a cooling jacket 2 on the engine parts that surrounds and/or is built in to the ERE parts that require cooling

Methodology Applied
Scientific EffectHeat conduction: Conduction (thermal)

Implementation Method 3

a radiator 6 containing one or more segments, including segments equipped with individual temperature regulators, and/or engine parts, including parts equipped with individual temperature regulators, that dissipate heat energy received from the heated working substance

Methodology Applied
Scientific EffectThermal radiation: Thermal Radiation

Implementation Method 4

a small circle thermostatic valve 5 that regulates working substance flow through the radiator, thereby keeping the temperature of the engine parts being cooled within a given range

Methodology Applied
Scientific EffectThermostatic regulation:

Implementation Method 5

an expansion tank 4 in the form of a hydraulic accumulator that ensures that the required pressure is maintained in the cooling system to prevent vapor formation and to prevent damage to ERE parts when there is overheating/overcooling by working substance during ERE operation

Methodology Applied
Scientific EffectPressure maintenance:

Implementation Method 6

a working substance storage reservoir 3 that provides the cooling system with working substance in the required quantity, including in the event of working substance loss during electric rocket engine operation, and that serves as a vapor condenser due to working substance mass and temperature when that heated portion of the working substance that had passed through the heated areas of the ERE passes through the reservoir

Methodology Applied
Scientific EffectCondensation: Condensation

Data Source

PatentEP3988784B1Electric rocket engine cooling system
Publication Date: 2024.11.27 CRYOGENIC & VACUUM SYST SIA
  • EP3988784B1 patent drawingFigure 1~2
  • EP3988784B1 patent drawingFigure 3~4

AI summary

The invention relates to rocket engine cooling systems. A proposed electric rocket engine forced cooling system comprises a pump designed to be capable of providing a continuous flow of propellant in the cooling system; a cooling jacket on the engine parts that surrounds the electric rocket engine parts; a reservoir for storing propellant; a hydraulic accumulator; a small circle thermostatic valve; a radiator; and tubes connecting the abovementioned system elements and capable of providing propellant circulation through the cooling system circles; moreover the outlet of the pump is connected with the inlet of the cooling jacket, the outlet of which is connected with the inlet of the hydraulic accumulator, the outlet of which is connected with the inlet of the pump, and moreover the outlet of the cooling jacket is also connected with the inlet of the reservoir, the outlet of which is connected with the inlet of the hydraulic accumulator and with the inlet of small circle thermostatic valve, the outlet of which is connected with the inlet of the pump and with the inlet of the radiator, the outlet of which is connected with the inlet of the pump.