Fuel Thermal Capacitance for Pulsed Aircraft Loads
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Solution Overview
Problem
High-energy systems like directed energy weapons pose challenges in thermal management due to transient energy demands, requiring efficient and lightweight cooling solutions that minimize size and weight without carrying excess capacity, especially in mobile platforms where size and weight are critical.
Innovation Solution
A thermal management system utilizing a thermal capacitance reservoir with fuel storage to absorb transient heat and maintain a constant temperature, employing two fuel loops and a variable mixing valve to regulate heat dissipation, allowing the cooling system to operate below peak load requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cooling system is sized to handle peak thermal loads, then thermal management capability is improved, but system size and weight increase
Solution Approach 1:
The system dynamically switches between two fuel loops based on thermal load conditions. The first fuel loop handles continuous thermal loads while the second fuel loop is activated during peak transient loads, allowing the cooling system to adapt its capacity dynamically rather than operating at fixed peak capacity continuously.
Solution Approach 2:
The fuel storage system serves dual functions: it acts as both the thermal management system (through the two fuel loops and heat exchangers) and as the fuel supply for the directed energy weapon. This multi-functionality eliminates the need for separate dedicated cooling system components, reducing overall system weight.
2Reliability
If a cooling system is designed for peak load capacity, then thermal management effectiveness is improved, but system complexity increases
Solution Approach 1:
The system merges the thermal management function with the existing fuel storage system by implementing two fuel loops that share the same fuel supply infrastructure. The first fuel loop connects to the continuous cooling system and the second fuel loop connects to the intermittent heat generating device, combining multiple functions into a unified system architecture.
Solution Approach 2:
The patent introduces a thermal capacitance reservoir as an intermediary component that buffers between the two fuel loops. This reservoir absorbs transient thermal loads and smooths temperature fluctuations, simplifying the control logic by providing thermal inertia rather than requiring complex real-time control during transient events.
3Weight of stationary object
If existing fuel storage systems are utilized for thermal management, then additional system weight is reduced, but thermal capacitance capacity is limited
Solution Approach 1:
The system pre-cools the fuel in the first fuel loop during periods of low or no thermal demand, storing thermal energy in the fuel before peak loads occur. This preliminary thermal preparation allows the system to handle peak loads more effectively using the pre-conditioned fuel, maximizing the thermal capacitance available within the existing fuel storage capacity.
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 manages peak thermal loads with minimal size and weight, maintaining a constant temperature and reducing energy consumption by using existing fuel storage systems, thus optimizing thermal management in high-energy applications.
Implementation Method 1
a first heat exchanger in thermal communication with the cooling system
Implementation Method 2
a second heat exchanger in thermal communication with the intermittent heat generating device
Implementation Method 3
The variable mixing valve may have a first input, a second input and an output to the second fuel loop. The first input may be from the first fuel loop and the second input may be from the second fuel loop. A ratio of the second input over the first input may be variable.
Implementation Method 4
The system utilizes the thermal capacitance (heat storage capacity) to absorb the transient heat output from the high energy systems and dissipates the extracted heat over time, and maintains the high energy system at a constant temperature.
Data Source
AI summary
A thermal management system for a pulse load on an aircraft. The thermal management system utilizing the reserve fuel from the aircraft to create thermal capacitance such that the instantaneous capacity of the cooling system to remove heat from the aircraft may be sized less than the rate of heat generated by the pulsed load (e.g. laser, radar, rail gun etc.) The reserve fuel is maintained at a temperature in a reservoir and cooled via a cooling system. Fuel from the reservoir is selectively mixed with fuel exiting the pulsed load heat exchanger to provide fuel to the inlet of the heat exchanger at a predetermined temperature, the temperature based at least upon the heat generated by the laser, flow rate of fuel and efficiency of the heat exchanger.