Pre-fabricated grease duct system
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Solution Overview
Problem
Current grease duct systems face issues with thermal expansion differences between inner and outer shells, leading to potential system failure, and on-site fabrication increases installation costs and risks due to lack of quality control.
Innovation Solution
A factory-built, pre-fabricated double-walled grease duct system with a tubular outer shell and inner liner, featuring a spacer with perforations and metal strips to manage thermal expansion and reduce heat transfer, along with high-temperature insulation for zero-clearance capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a double-walled grease duct system is used to achieve zero-clearance capability, then safety and insulation performance are improved, but thermal expansion difference between inner liner and outer shell causes stress build-up and potential failure
Solution Approach 1:
The spacer is divided into multiple vertical metal strips instead of a continuous structure. This segmentation allows each strip to independently manage thermal expansion forces, reducing stress concentration and preventing catastrophic failure of the inner liner while maintaining the zero-clearance capability of the double-walled system
Solution Approach 2:
The metal strips are positioned at specific locations within the annular space to provide localized support where thermal expansion stress is most critical. This targeted approach strengthens the inner liner at key stress points while allowing other areas to accommodate thermal movement, resolving the contradiction between system reliability and inner liner strength
2Adaptability or versatility
If on-site fabrication is performed to accommodate different installation dimensions, then adaptability is improved, but installation cost and time increase due to lack of quality control
Solution Approach 1:
The duct system is designed with standardized modular components that can be configured for different installation scenarios. The universal design allows factory fabrication with full quality control while maintaining adaptability to various dimensions and requirements, eliminating the need for time-consuming on-site custom fabrication
Solution Approach 2:
All duct components are pre-fabricated and pre-assembled in the factory before delivery to the installation site. This preliminary action ensures high-quality manufacturing under controlled conditions and reduces on-site work to simple assembly, significantly improving installation efficiency while maintaining adaptability through modular design
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 solution effectively mitigates thermal expansion-induced stress, simplifies installation, reduces costs, and enhances safety by allowing independent expansion and contraction of components while maintaining system dimensions, thereby preventing failures like fatigue and rupture.
Implementation Method 1
The extreme temperature in the system creates a thermal expansion difference between the inner liner and outer shell, meaning that the metal comprising the inner liner and outer shell expand and contract at difference rates
Implementation Method 2
The annular space can be filled with a high-temperature insulation material
Data Source
AI summary
The present double walled grease duct includes a tubular outer shell surrounding a tubular inner liner, wherein a spacer is positioned perpendicular to the walls of the outer shell and the inner liner. The spacer can include a plurality of vertical metal strips extend from a top edge of the spacer to the bottom edge of the spacer, wherein the top edge of the spacer contacts the walls of the outer shell and wherein the bottom edge of the spacer contacts the walls of the inner liner. The metal strips resist the different rates of thermal expansion between the outer shell and inner liner ultimately preventing the collapse of the inner liner under pressure from thermal expansion.