Heating Box Parallel Channels Preform Thermal Conditioning
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Solution Overview
Problem
Conventional heating devices for thermoplastic preforms in blow molding machines face inefficiencies in energy usage and temperature profiling due to excessive heat loss and blurring of temperature boundaries, particularly when using closed radiation chambers.
Innovation Solution
A heating box design with parallel heating channels and a single heating unit that radiates on both sides, utilizing bar-shaped radiation shields to prevent overheating and enhance energy efficiency by shielding unwanted radiation, while allowing for more powerful heating elements and improved temperature profiling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If closed radiation chambers are used to improve energy efficiency through reflected radiation, then energy savings are achieved, but temperature profile sharpness deteriorates due to blurring of temperature boundaries
Solution Approach 1:
The heating box is divided into multiple heating zones with independent temperature control along the transport direction. Each zone can be controlled separately to maintain sharp temperature boundaries while utilizing reflected radiation within each zone for energy efficiency.
Solution Approach 2:
Different wall sections of the heating box are assigned different thermal properties - some areas have high reflectivity to conserve energy, while other areas are designed with selective radiation characteristics to maintain precise temperature profiling in specific zones.
2Manufacturing precision
If open radiation spaces are used to achieve sharp temperature profiles, then temperature boundary definition is improved, but energy loss increases due to unreflected thermal radiation
Solution Approach 1:
Reflector elements are strategically positioned as intermediaries between the heating elements and the preforms. These reflectors redirect thermal radiation to specific target areas, maintaining temperature profile sharpness while reducing overall energy loss by capturing and redirecting otherwise lost radiation.
3Loss of energy
If reflector structures are added to improve radiation distribution, then energy efficiency improves, but heat loss to reflector material increases requiring active cooling
Solution Approach 1:
A fluid cooling system is integrated into the reflector structure, with cooling channels positioned to efficiently remove heat from the reflector material. This allows the reflector to maintain its high reflectivity and energy efficiency function while preventing excessive heat accumulation through active thermal management.
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 design significantly improves energy efficiency and temperature profiling by reducing heat loss, allowing for sharper temperature profiles and increased energy deposition on the preforms, while also enabling a higher loading density and more efficient use of radiant energy.
Implementation Method 1
Near-infrared emitters (NIR) are usually provided inside the heating boxes to generate heating radiation
Implementation Method 2
Reflectors reflecting thermal radiation can be arranged behind the radiators
Implementation Method 3
utilizing bar-shaped radiation shields to prevent overheating and enhance energy efficiency by shielding unwanted radiation
Data Source
Figure 1~1A
Figure 2~3
Figure 4~8
AI summary
The invention relates to a heat box for thermally conditioning preforms (10) that consist of a thermoplastic material and are provided for blow moulding, in which two lateral walls (32) and one base wall (34) delimit a heat tunnel through which the preforms (10) are conveyed, said heat tunnel comprising at least two parallel heat channels, and a heating unit (14) being arranged between two adjacent, particularly parallel heat channels and comprising a plurality of rod-shaped heating elements (16) that extend longitudinally in the conveyor direction of the preforms (10).