Cooking release sheet and method of making same
Solution Overview
Problem
Existing cooking release sheets for clamshell grills face challenges in providing uniform and efficient heat transfer, maintaining structural integrity at high temperatures, and ensuring food safety by preventing thermal or chemical degradation, while avoiding the use of composite reinforcements that may contaminate food.
Innovation Solution
A laminate of two layers of fibrillated polytetrafluoroethylene (PTFE) films is used, with fibrils extending in different directions, forming a laminate with a nominal thickness of less than 4.5 mils, to minimize expansion and maximize heat transfer, and a heat transfer coefficient of at least 0.150 W/mK.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the release sheet is made thinner to improve heat transfer speed, then heat transfer efficiency is improved, but structural integrity and resistance to high temperature deformation deteriorate
Solution Approach 1:
The patent uses a composite structure consisting of multiple layers of PTFE film laminated together. This composite approach allows the release sheet to maintain thinness for heat transfer efficiency while the multiple layers collectively provide the structural integrity needed to withstand high temperatures without deforming. The lamination creates a stronger material that balances both thermal conductivity and mechanical strength requirements.
Solution Approach 2:
The patent transitions from a single-layer thin film to a multi-layer laminated structure. By adding the dimension of layer multiplication, the solution achieves both rapid heat transfer (through maintaining overall thinness) and structural stability (through the combined strength of multiple layers working together).
2Strength
If composite reinforcement materials are added to provide structural strength, then structural integrity is improved, but food safety is compromised due to potential contamination
Solution Approach 1:
The patent changes the material parameter from composite materials (which may contain food-contact concerns) to pure PTFE. By maintaining the base material as food-safe PTFE and using lamination rather than adding foreign reinforcement materials, the solution achieves structural integrity without introducing potential contamination risks. The material composition remains purely food-contact safe throughout.
Solution Approach 2:
The patent employs disposable PTFE release sheets that are replaced rather than reused. This approach eliminates the need for long-term durability through composite reinforcement, as each new sheet provides fresh structural integrity without the wear and degradation issues that could lead to material breakdown and food contamination in reusable composite systems.
3Productivity
If the release sheet is made thinner for rapid heat transfer, then cooking speed is improved, but resistance to high heat deformation worsens
Solution Approach 1:
The patent creates a composite structure through lamination of multiple PTFE layers. This composite construction allows the release sheet to remain thin for rapid heat transfer and high cooking speed, while the multiple laminated layers collectively provide the thermal stability and resistance to deformation needed when exposed to high cooking temperatures.
Solution Approach 2:
The patent divides the release sheet into multiple separate PTFE layers that are laminated together. This segmentation allows each layer to contribute to both the thinness required for fast heat transfer and the collective structural stability needed to resist high-temperature deformation, with the layers working together as a unified structure.
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 laminate provides uniform heat transfer, maintains structural integrity, and ensures food safety by reducing thermal expansion and chemical degradation, while allowing easy cleaning and repeated use without contaminating food.
Implementation Method 1
The first layer is a fibrillated polytetrafluoroethylene film with first fibrils generally extending in a first layer direction. The second layer is a fibrillated polytetrafluoroethylene film with second fibrils generally extending in a second layer direction.
Implementation Method 2
the release sheet must be capable of withstanding the high heat from the upper heating element without deforming, particularly given that it is suspended from the upper heating element
Data Source
AI summary
A cooking release sheet of the type typically used in a clam shell cooker is fabricated as a laminate of at least two thin laminated layers of fibrillated polytetrafluoroethylene film and not prestressing the laminate exhibits less expansion when exposed to elevated temperatures. The material provides a uniform and efficient heat transfer that can withstand the high heat necessary for rapid cooking without deforming, and that is readily cleanable and does not negatively impact food safety issues resulting from wear, damage, or thermal or chemical degradation.