Cold-Worked Stainless Steel Induction Food Warming Without Fan Noise
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Solution Overview
Problem
Traditional food warming and holding systems using steam tables are inefficient due to thermal inertia, unpredictable temperature control, and require a water supply, while induction heating is not compatible with non-magnetic materials like 300-series stainless steel, leading to noise from cooling fans.
Innovation Solution
A system using induction heating with a pan or tray made of cold-worked 303 stainless steel, operated at a frequency of 40-60 kHz, with an induction coil having 40-80 turns and low coil current to minimize heat generation, allowing for quiet and efficient heating without fans, and a temperature sensor for closed-loop control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If steam tables are used for food warming, then food can be heated, but the heating is slow due to thermal inertia of water and temperature control is difficult
Solution Approach 1:
The patent replaces the mechanical steam heating system with an electromagnetic induction heating system. The induction heating unit generates an electromagnetic field that directly induces eddy currents in the magnetic pan, converting electromagnetic energy to thermal energy without requiring water or steam, thereby eliminating thermal inertia and enabling fast, predictable temperature control.
Solution Approach 2:
The patent changes the heating mechanism from thermal conduction through water/steam to electromagnetic induction. By adjusting parameters such as operating frequency (20-100 kHz) and power level, the system achieves rapid and predictable temperature control that overcomes the slow response and instability of steam table heating.
2Use of energy by moving object
If induction heating is used with non-magnetic 300-series stainless steel pans, then heating can be achieved, but cooling fans are required which create noise
Solution Approach 1:
The patent modifies the magnetic properties of the pan material through cold working processes, increasing its relative magnetic permeability from less than 1.05 to greater than 1.05. This enables effective induction heating of 300-series stainless steel pans without requiring high-power cooling systems, thereby eliminating or reducing cooling fan noise while maintaining heating efficiency.
3Adaptability or versatility
If cold-worked 303 stainless steel is used for pans, then induction heating compatibility is improved, but the material processing complexity increases
Solution Approach 1:
The patent utilizes cold working processes (such as rolling, drawing, or pressing) that are already standard in the cookware manufacturing industry to increase the magnetic permeability of 300-series stainless steel. These processes inadvertently create the desired magnetic properties for induction heating compatibility without requiring additional specialized manufacturing steps, thus maintaining ease of manufacture while achieving induction heating compatibility.
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
Enables efficient, fast, and predictable heating of food using induction heating on non-magnetic stainless steel pans, reducing energy consumption and eliminating the need for cooling fans, resulting in a quieter and more efficient food warming system.
Implementation Method 1
the pan or tray is heated using an induction heating unit... an induction inverter is used which operates in a preferred frequency range of about 40-60 kHz
Implementation Method 2
an induction coil having 40-80 turns and low coil current to minimize heat generation
Data Source
AI summary
A method for holding and warming food. The method includes the steps of: using a container formed of 300-series stainless steel, wherein the container is formed by a cold working process; and applying to the container a magnetic field from an induction coil, wherein the magnetic field is sufficient to induce a current in the container to heat the container.