Radiant tube
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Solution Overview
Problem
Existing radiant tubes face challenges in achieving high heat transfer efficiency while maintaining a simple structure and low manufacturing cost, as well as managing pressure loss and thermal deformation due to the insertion of heat transfer promoters.
Innovation Solution
A radiant tube design featuring a conduit with heat transfer promoters having a body part and protruding parts arranged circumferentially, with a specific gap between the protruding parts and the conduit inner wall, allowing for improved heat transfer efficiency and reduced pressure loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a heat transfer promoter with a complicated spiral structure is used to increase heat transfer efficiency, then the heat transfer coefficient is improved, but the manufacturing cost increases
Solution Approach 1:
The heat transfer promoter is divided into multiple protruding parts (5 to 10 protrusions) extending from the inner wall of the conduit into the flow passage. Each protruding part has a simple shape that can be easily manufactured, yet collectively they create the desired heat transfer enhancement through increased surface area and flow disturbance without requiring complex spiral geometries
Solution Approach 2:
The protruding parts are strategically positioned at specific locations along the conduit where heat transfer enhancement is most needed. The local geometry of each protrusion is optimized to create effective flow separation and reattachment patterns that enhance convective heat transfer, while maintaining overall structural simplicity for cost-effective manufacturing
2Use of energy by moving object
If the flow passage area is reduced to improve gas flow velocity and heat transfer coefficient, then heat transfer efficiency is improved, but the pressure loss increases
Solution Approach 1:
The protruding parts occupy only a portion of the flow passage cross-section rather than completely blocking it. The height and spacing of the protrusions are carefully controlled to achieve sufficient flow velocity increase and heat transfer enhancement while leaving enough open area for gas flow, thereby limiting pressure loss to acceptable levels
Solution Approach 2:
Instead of reducing flow passage area in the cross-sectional plane, the invention extends heat transfer surface area in the longitudinal dimension by adding protruding elements that extend into the flow. This creates additional heat transfer surfaces without significantly blocking the main flow path, thus improving heat transfer while maintaining relatively low pressure drop
3Use of energy by moving object
If heat transfer promoters are inserted into the conduit to enhance heat transfer on the downstream side, then heat utilization rate is improved, but the device complexity increases
Solution Approach 1:
The heat transfer promoter serves multiple functions simultaneously: it enhances convective heat transfer through flow disturbance, increases the effective heat transfer surface area, and can be designed to withstand thermal expansion and contraction. The simple protruding geometry allows for easy installation and removal, and the structure can accommodate thermal deformation without compromising functionality
Solution Approach 2:
The protruding parts are designed to work passively with the flowing gas, utilizing the gas flow itself to create the desired heat transfer enhancement. The geometry of the protrusions naturally creates flow separation and reattachment patterns that enhance mixing and heat transfer without requiring active control mechanisms or complex moving parts
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 design enhances heat transfer efficiency while maintaining a simple structure and low manufacturing cost, facilitating stable operation and efficient heat transfer to objects outside the conduit.
Implementation Method 1
the combustion gas generated by the gas generating part flows along a gas flow passage formed by the conduit. Consequently, the conduit is in a high temperature state due to the heat transfer from the combustion gas
Implementation Method 2
The radiant tube indirectly heats an object to be heated that is present outside the conduit, by the radiant heat from the conduit heated by the combustion gas generated by the gas generating part
Implementation Method 3
the combustion gas is made to flow to the outlet of the conduit while spirally swirling in the latter half of the conduit of the radiant tube, thereby increasing the relative velocity between the conduit and the combustion gas to increase the convective heat transfer coefficient
Data Source
AI summary
A radiant tube includes a conduit; and one or more heat transfer promoters disposed in the conduit, wherein the heat transfer promoter includes a body part on a center side of the conduit, and protruding parts protruding from the body part toward an inner wall surface of the conduit, the protruding parts are on an outer periphery of the body part to be arranged in a circumferential direction of the conduit, the protruding parts includes first protruding parts having a distal end portion facing the inner wall surface across a gap ΔL, and a second protruding part, the number of first protruding parts is greater than the number of second protruding parts, and a ratio (ΔL/Dt) of the gap ΔL to an equivalent diameter Dt of a conduit portion is x %, where the heat transfer promoter is disposed, and formula (1) is satisfied: 0.3%<x<7%.