Jumping Drop Vapour Chamber Thermal Diode for Missile Electronics
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Solution Overview
Problem
Current missile systems face challenges in managing the heat generated by complex electronics components, which require precise temperature control to operate effectively over extended periods, especially when the missile skin becomes a source of heat due to air friction during high-speed flight.
Innovation Solution
A thermal link using a jumping drop vapour chamber, which acts as a thermal diode, is implemented between the electronics unit and the missile outer skin, allowing heat transfer from the electronics to the skin when necessary and insulating when the skin is hotter, along with a thermal capacitor to absorb heat and maintain optimal temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the missile skin is used as a heat dump for electronics, then heat dissipation from electronics is improved, but when the missile moves at high speeds the skin becomes a heat source and electronics overheat
Solution Approach 1:
The patent employs a dynamic thermal management system using a shape memory alloy that automatically changes its thermal conductivity based on the temperature difference between the skin and electronics. When skin temperature exceeds electronics temperature by a threshold, the alloy transitions to a thermally insulating state, preventing heat flow from skin to electronics. This dynamic adaptation resolves the contradiction by making the thermal link responsive to operating conditions rather than fixed.
Solution Approach 2:
The shape memory alloy changes its physical state (phase transition) in response to temperature parameters, transforming from a thermally conductive state to a thermally insulating state. This parameter change allows the system to adapt its thermal properties based on the temperature gradient between skin and electronics, enabling the same structure to serve both as heat sink and heat isolator under different conditions.
2Temperature
If a shape memory alloy and spring mechanism is used to control thermal connection, then thermal management is improved, but mechanical complexity increases
Solution Approach 1:
The shape memory alloy acts as a self-regulating thermal valve that automatically responds to temperature differences without external control. The alloy's phase transition is triggered by the temperature gradient itself, creating a self-service system that eliminates the need for sensors, actuators, or control electronics. This self-service mechanism reduces system complexity while maintaining effective thermal management.
Solution Approach 2:
The shape memory alloy serves as an intermediary element between the skin and electronics, mediating heat flow based on thermal conditions. This intermediary component simplifies the overall system by replacing complex mechanical switching mechanisms with a material that inherently responds to thermal gradients, reducing the number of moving parts and control elements required.
3Temperature
If mechanical systems are used for thermal control, then thermal management is achieved, but reliability decreases due to jamming or sticking from dirt accumulation
Solution Approach 1:
The patent replaces mechanical switching systems with a thermally-actuated shape memory alloy mechanism. Instead of using motors, solenoids, or manual switches that can jam or stick, the system uses a material that passively responds to temperature differences through phase transition. This substitution of active mechanical systems with a passive thermal-responsive material significantly improves reliability by eliminating components susceptible to dirt accumulation and mechanical failure.
Solution Approach 2:
The invention extracts and eliminates the vulnerable mechanical components (springs, moving parts, connectors) from the thermal control system. By using a shape memory alloy that deforms and changes thermal conductivity through phase transition alone, the system removes the elements that would otherwise be prone to jamming and sticking, leaving a more reliable thermal management solution.
Data Source
AI summary
There is disclosed a missile comprising an outer skin, an electronics unit, and a thermal link between the electronics unit and the outer skin. The thermal link comprises a jumping drop vapour chamber arranged such that, when the outer skin is at an elevated temperature relative to the electronics unit, the electronics unit is thermally insulated from the outer skin; and such that, when the outer skin is at a lower temperature relative to the electronics unit, the electronics unit is thermally linked to the outer skin.