Heater Plate Embedded Pyrolytic Graphite Thermal Diffusion
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Solution Overview
Problem
Existing heater plates face challenges in achieving uniform temperature due to the thermal conductivity of materials used and geometric factors, resulting in significant thermal non-uniformity, even with advanced designs and constructions.
Innovation Solution
Incorporating a thermally annealed pyrolytic graphite (TPG) layer between the heater and the critical surface of the plate, which significantly enhances thermal conductivity and uniformity by distributing heat evenly across the surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional heater materials and construction are used, then the heater can be manufactured with standard materials, but the temperature uniformity across the surface deteriorates with a maximum-minimum range of 15-20°C
Solution Approach 1:
The patent applies composite materials by combining pyrolytic graphite with metal plates to create a hybrid structure. The pyrolytic graphite layer is sandwiched between metal plates containing heater elements, leveraging the superior in-plane thermal conductivity of graphite (4 times that of copper) while maintaining the structural benefits of metal construction. This composite approach resolves the contradiction by achieving exceptional temperature uniformity without requiring overly complex manufacturing processes.
Solution Approach 2:
The patent applies local quality by positioning the high-conductivity pyrolytic graphite layer specifically at the interface where heat distribution is most critical. The graphite layer is placed between the heater element and the critical surface, concentrating the thermal management function where it is needed most rather than uniformly throughout the entire heater structure.
2Temperature
If material options are expanded to improve thermal conductivity, then temperature uniformity improves, but the selection is limited by temperature rating, chemical compatibility, or thermal expansion
Solution Approach 1:
The patent applies parameter changes by utilizing the anisotropic thermal conductivity properties of pyrolytic graphite. The material exhibits extremely high in-plane thermal conductivity (k values 4 times that of copper) while maintaining compatibility with standard metal plates. By changing the orientation and layering parameters of the graphite material, the system achieves superior heat distribution without sacrificing temperature rating or chemical compatibility.
3Use of energy by moving object
If heat is concentrated at the heater element location, then efficient heating is achieved, but thermal non-uniformity increases due to asymmetric losses and geometry
Solution Approach 1:
The patent applies the intermediary principle by introducing the pyrolytic graphite layer as a thermal mediator between the heater element and the critical surface. The graphite layer receives concentrated heat from the heater element and redistributes it laterally across the surface, acting as an intermediate heat transfer medium that decouples the heat source location from the temperature distribution pattern.
Solution Approach 2:
The patent applies dimensionality change by utilizing the in-plane thermal conductivity of the pyrolytic graphite layer to transport heat laterally across the surface. This creates a two-dimensional heat distribution network that spreads heat from the one-dimensional heater element location, effectively adding a lateral heat transport dimension to the thermal management system.
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 integration of a TPG layer reduces temperature gradients, achieving a more uniform temperature distribution with a standard deviation of ±7°C compared to ±17°C in standard designs, representing a 59% improvement in thermal uniformity.
Implementation Method 1
TPG is sometimes referred to as 'hyper conductive' due to its having a thermal conductivity about four times that of copper. The high, in-plane thermal conductivity coefficient k allows for only shallow gradients.
Data Source
AI summary
A heater plate is constructed with an embedded thermal diffusion layer of pyrolytic graphite to provide increased temperature uniformity in a critical heating surface. The heater has first and second metal plates with a heater element contained within the first plate and a core of the pyrolytic graphite diffusion layer sandwiched between the heater element and the second metal plate. The diffusion layer may be sputter metal coated to improve bonding of the layer to the plates.