3D Phase Change Cooling for High Power LED Thermal Management
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Solution Overview
Problem
High power LEDs face significant thermal management challenges due to inefficient heat dissipation, leading to increased junction temperatures, reduced efficiency, and potential thermal failure, which is exacerbated by the high cost of conventional cooling systems like heat pipes and vapor chambers.
Innovation Solution
A 3-D phase change heat exchange structure using a liquid to vapor phase change material (L-V PCM) within a sealed enclosure with hollow fins, effectively spreading heat from a small chip area to a larger surface area, reducing thermal resistance and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional cooling systems like heat pipes and vapor chambers are used, then heat dissipation performance is improved, but system cost increases significantly
Solution Approach 1:
The patent employs phase change material (PCM) that transitions from solid to liquid state to absorb and store thermal energy from LED chips. The PCM is contained in cavities within the heat sink structure, creating a passive cooling system that eliminates the need for expensive active components like heat pipes and vapor chambers while maintaining effective heat dissipation performance.
2Productivity
If injection current density is increased to reduce cost per lumen, then light power output is improved, but heat generation increases leading to thermal runaway
Solution Approach 1:
The patent changes the thermal management approach by introducing phase change material with specific melting points (e.g., 25°C, 50°C, 75°C, 100°C) to actively absorb heat at critical temperature thresholds. This allows the system to handle higher injection current densities and generate more light power while maintaining junction temperature control through the PCM's phase transition heat absorption mechanism.
3Device complexity
If passive heat sink is used, then system complexity is reduced, but thermal resistance is too high for high injection current applications
Solution Approach 1:
The patent creates a composite heat sink structure that combines conventional solid heat sink material with phase change material. The PCM is integrated into cavities within the heat sink, forming a composite system that maintains the structural simplicity of passive heat sinks while dramatically reducing thermal resistance through the high heat absorption capacity of the phase change material during its solid-to-liquid transition.
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 significantly reduces the system-level thermal resistance of LED luminaires, enhancing light power output and lifespan while lowering the cost of the cooling system, making it more practical for high power LED applications.
Implementation Method 1
a liquid to vapor phase change material (L-V PCM) disposed inside the chamber
Implementation Method 2
Q=hAΔT where Q is the heat transfer power (W), h is the heat transfer coefficient (W/(m2·K)), A is the area of thermal pass, and ΔT is the temperature gradient or difference
Implementation Method 3
The hollow spaces and the chamber forming a sealed space
Implementation Method 4
Rexter relates to the thermal resistance from the TIM to the atmosphere
Data Source
AI summary
Novel 3-D super-thermal conducting heat management design and delayed cooling using phase change materials are adopted to lower the temperature inside LEDs and other devices. The cooling mechanism uses a fin structure with hollow fins to dissipate heat to the environment. The hollow space inside the fins is connected to an interior chamber, where a liquid to vapor phase change material (L-V PCM) is provided to transfer heat from the LED chips to the surface of the hollow fins. The LED chips are mounted on an evaporator located at the bottom of the chamber. A liquid reservoir is provided, and the evaporator surface is hydrophilic with an additional wick structure to transport the L-V PCM liquid to the evaporator surface. The fins are parallel to each other and are either parallel or perpendicular to the evaporator surface. This structure has superior performance and is inexpensive to manufacture.