Thermal Recirculation Control for Aircraft Fuel Cooling

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Solution Overview

Problem

Traditional fuel systems in aircraft require high mechanical loads to drive fuel pumps, leading to increased parasitic energy losses due to the placement of engine-mounted coolers upstream of airframe-mounted coolers.

Innovation Solution

A system that includes a main supply line, a thermal recirculation pump, and a thermal recirculation control, which allows for the recirculation of fluid at elevated pressure to coolers, reducing the mechanical load on fuel pumps and optimizing cooler control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If engine-mounted coolers are placed upstream of airframe-mounted coolers, then cooling function is provided, but total pressure requirements of the pump become very high

Engineering Contradiction:

Improvecooling functionVSAvoidtotal pressure requirements

Core Design Contradiction:

TemperatureVSStress or pressure

Solution Approach 1:

The cooling system is divided into separate engine-mounted coolers and airframe-mounted coolers, with thermal recirculation control allowing independent flow management. This segmentation enables the fuel pump to serve multiple cooling functions without requiring excessively high pressure, as the system can recirculate thermal energy efficiently through controlled flow paths.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A thermal recirculation control mechanism acts as an intermediary between the engine-mounted coolers and airframe-mounted coolers. This control system manages the thermal recirculation flow, allowing heat exchange optimization without requiring the fuel pump to generate extremely high pressures, thereby resolving the pressure-temperature trade-off.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Temperature

If high pressure is provided to drive fuel pumps, then cooling function is improved, but mechanical loads increase

Engineering Contradiction:

Improvecooling efficiencyVSAvoidmechanical loads

Core Design Contradiction:

TemperatureVSForce

Solution Approach 1:

The thermal recirculation control system incorporates feedback mechanisms that monitor thermal conditions and adjust flow rates accordingly. This feedback control allows the system to achieve effective cooling without continuously operating at high mechanical loads, as the pump pressure can be modulated based on actual thermal demands detected by the control system.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system transitions from static high-pressure operation to dynamic pressure control through the thermal recirculation mechanism. The fuel pump pressure and flow rate can vary dynamically based on thermal conditions, allowing the system to maintain cooling effectiveness while minimizing mechanical loads when full pressure is not required.

Inventive Principle:

Principle #15Dynamics

3Quantity of substance

If high mechanical loads are used to drive pumps, then fluid flow is increased, but parasitic energy loss increases

Engineering Contradiction:

Improvefluid flowVSAvoidparasitic energy loss

Core Design Contradiction:

Quantity of substanceVSLoss of energy

Solution Approach 1:

The system converts what would be waste heat into useful thermal energy by implementing thermal recirculation. The thermal recirculation control captures thermal energy that would otherwise be lost and redirects it through the cooler system, maintaining effective fluid flow for cooling while reducing the parasitic energy loss associated with high-pressure pump operation.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The thermal recirculation control system changes the operational parameters of the fuel pump by allowing variable flow rates and pressures based on thermal demands. This parameter modulation enables the system to achieve necessary fluid flow for cooling while operating the pump at lower average pressures, thereby reducing parasitic energy losses.

Inventive Principle:

Principle #35Parameter changes

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 solution reduces the weight of fuel systems, decreases the pump rise required for thermal management, and minimizes parasitic power consumption compared to traditional systems.

Implementation Method 1

providing fluid at an elevated pressure to the thermal recirculation line relative to the main supply line

Methodology Applied

Scientific EffectPressure gradient: Pressure Gradient

Implementation Method 2

A cooler system of one or more coolers is connected in fluid communication with a cooler supply line of the thermal recirculation control

Methodology Applied

Scientific EffectHeat exchange: Heat Exchanger

Data Source

PatentUS12241418B2Dedicated thermal recirculation control

Publication Date: 2025.03.04 HAMILTON SUNDSTRAND CORP

AI summary

A system includes a main supply line and a thermal recirculation pump in fluid communication with the main supply line for supplying the thermal recirculation pump. The thermal recirculation pump is connected in fluid communication with a thermal recirculation line for providing fluid at an elevated pressure to the thermal recirculation line relative to the main supply line. A thermal recirculation control is connected in fluid communication to be supplied from the thermal recirculation line. A cooler system of one or more coolers is connected in fluid communication with a cooler supply line of the thermal recirculation control.