Variable Resistance Screw for Plastic Waste Heat Treatment
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Solution Overview
Problem
Existing heat treatment devices are not adapted to treat a wide range of materials, particularly plastics waste, which melt slowly due to their slow increase in temperature, leading to inefficient heat transfer and prolonged processing times.
Innovation Solution
The heat treatment device features a screw with varying electrical resistance along its axis, allowing for a customizable temperature profile that matches the specific treatment requirements of the substance, ensuring consistent temperature difference between the screw and the substance for enhanced heat transfer, either by maintaining higher outlet temperatures when empty or higher inlet temperatures when processing plastics to accelerate melting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a screw with constant resistance is used for heating, then the device structure is simple, but the temperature profile cannot be optimized for different substances leading to slow melting of plastics waste
Solution Approach 1:
The screw is designed with non-uniform electrical resistance distribution along its length, creating different heating zones. The resistance increases from inlet to outlet, generating higher temperatures at the outlet where plastics waste needs accelerated melting. This local differentiation of heating intensity solves the contradiction by optimizing melting speed without requiring a completely complex device structure.
Solution Approach 2:
The electrical resistance parameter of the screw is deliberately varied along its axis to create a specific temperature profile. By changing the resistance parameter from constant to variable, the system achieves optimized heat transfer and faster melting of plastics waste, while the variation follows a predictable gradient that maintains manufacturing feasibility.
2Productivity
If the screw temperature is increased to accelerate melting, then the heat treatment effectiveness improves, but the energy consumption increases
Solution Approach 1:
Instead of uniformly heating the entire screw, the system applies heating locally where most needed - at the outlet zone where resistance is highest and plastics waste requires accelerated melting. This localized high-temperature zone reduces overall energy consumption while maintaining effective heat treatment where it matters most.
Solution Approach 2:
The variable resistance distribution ensures continuous and optimized heat transfer along the screw length. The gradual increase in resistance creates a continuous temperature gradient that maintains optimal temperature difference between screw and material throughout the heating zone, maximizing energy utilization efficiency and reducing wasted energy.
3Reliability
If the screw temperature varies along its length, then the heat transfer efficiency improves, but the manufacturing complexity of the screw increases
Solution Approach 1:
The screw manufacturing is simplified by implementing resistance variation through local modifications rather than complete redesign. Methods such as selective winding of heating elements or localized material composition changes allow the outlet zone to have higher resistance while keeping the inlet zone simpler, balancing manufacturing ease with heat transfer efficiency.
Solution Approach 2:
The screw is conceptually divided into zones with different resistance characteristics - a lower resistance inlet zone and a higher resistance outlet zone. This segmentation allows independent optimization of each zone and simplifies manufacturing by treating them as distinct sections that can be produced separately or with different processes.
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 adaptation enables the device to effectively treat a broader range of substances by optimizing heat transfer, reducing processing time for plastics and improving overall recycling efficiency.
Implementation Method 1
heater means for heating the screw by the Joule effect
Implementation Method 2
transfers of heat by conduction take place between each unit length of the screw and the substance being conveyed
Implementation Method 3
the granules soften progressively inside the enclosure until they melt
Data Source
AI summary
A device for the heat treatment of a product includes an enclosure, a conveyor for transporting the product between an inlet of the enclosure and an outlet of the enclosure, which comprise a screw mounted in such a way as to rotate in the enclosure according to a geometric rotational axis, and a heater for heating the screw by Joule effect. The screw has an electrical resistance that varies along the geometric rotational axis.