Radiant Screen Slots Reduce Heat Loss
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Solution Overview
Problem
Gas fired radiant emitters used for heating continuously moving substrates face inefficiencies due to heat loss through conduction and the need for insulation in fixing the radiant screen, which affects the emitter's performance and longevity.
Innovation Solution
A metal plate with elongated slots acting as a radiant screen is used, where the slots create interruptions in heat conduction, allowing for simpler fixation with reduced insulation needs, and optimizing the perforated area for enhanced radiation efficiency and thermal expansion management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a metal plate radiant screen is used without interruptions, then heat conduction across the plate is efficient, but heat is lost through the fixation system and insulation materials are required
Solution Approach 1:
The metal plate radiant screen is segmented by introducing elongated slots that divide the continuous plate into sections. This segmentation interrupts heat conduction pathways across the plate, localizing heat to specific regions and reducing heat loss through the fixation system at the borders.
Solution Approach 2:
The slots are strategically positioned and sized to create local variations in thermal properties. By controlling the distribution and geometry of slots, the invention creates zones with different thermal characteristics, allowing optimization of heat retention in critical areas while maintaining overall radiation efficiency.
2Loss of energy
If the perforated area of the metal plate is increased, then heat conduction is reduced, but radiation efficiency decreases
Solution Approach 1:
The invention optimizes parameters including slot width, slot length, slot spacing, and overall perforated area percentage. By carefully selecting these parameters, the design achieves the right balance between interrupting heat conduction and maintaining sufficient solid metal area for effective thermal radiation to the substrate.
3Productivity
If the metal plate borders are hotter, then radiation efficiency is improved, but fixation complexity increases and insulation material is required
Solution Approach 1:
The slots create thermal zones that allow the central regions of the metal plate to maintain higher temperatures for effective radiation, while the bordered regions near slots remain cooler. This thermal segmentation enables simpler fixation methods at the cooler borders without compromising the temperature and radiation efficiency of the active heating zones.
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 results in higher efficiency and longer emitter lifetime by minimizing heat loss and accommodating thermal expansion, while maintaining a low perforated area for improved radiation efficiency.
Implementation Method 1
The slots on the metal plate create interruptions to the conduction of heat over the surface of the metal plate
Implementation Method 2
a metal plate provided at the combustion side of the burner deck... to act as radiant screen
Implementation Method 3
The metal plate comprises a plurality of elongated slots for passage through the metal plate of flue gas generated on the burner deck
Data Source
Figure 1~2
Figure 3~4
AI summary
A gas fired radiant emitter comprises a burner deck onto which premix gas is combusted when the emitter is in use; and a metal plate provided at the combustion side of the burner deck. The metal plate is provided to act as radiant screen when the emitter is in use. The metal plate is at least over part of its surface spaced from the burner deck. The metal plate comprises a plurality of elongated slots for passage through the metal plate of flue gas generated on the burner deck. The plurality of elongated slots comprise a first elongated slot. The first elongated slot has a first tangent along a position along the length of the first elongated slot. The plurality of elongated slots comprise a second elongated slot. The second elongated slot has a second tangent along a position along the length of the second elongated slot. The angle between the first tangent and the second tangent is between 45° and 135°.