Polymeric Coil Assembly Tube Alignment and Heat Transfer
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Solution Overview
Problem
Existing polymeric coil assemblies for heat exchange systems face challenges in maintaining optimal tube spacing and positional relationship, leading to reduced heat transfer efficiency, especially at return bends, due to bundling and support issues, which affects both air and water flow.
Innovation Solution
A polymeric coil assembly design featuring an array of tubes with appropriate spacing and alignment through tube spacers, maintaining relative positional relationships in both passes and return bends, and integrating a water distribution subassembly within the coil assembly to enhance heat transfer and water distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If polymeric tubes are used instead of metal tubes, then weight is reduced, but heat transfer efficiency deteriorates due to bundling and spacing issues
Solution Approach 1:
The coil assembly is segmented into multiple passes with spacers dividing the tubes into separate bundles. This segmentation prevents excessive bundling in any single location, maintaining proper spacing between tubes and ensuring consistent heat transfer efficiency across the entire coil assembly while preserving the weight advantages of polymeric tubes.
Solution Approach 2:
Different regions of the coil assembly are designed with different spacer configurations tailored to local heat transfer requirements. Return bends and pass transitions receive enhanced spacing and support structures, while straight sections use standard spacer configurations. This localized optimization ensures uniform heat transfer performance throughout the assembly.
2Productivity
If tube spacing is reduced to increase heat transfer area, then heat transfer capacity improves, but air and water flow deteriorate due to restricted passages
Solution Approach 1:
The coil assembly utilizes multiple spatial dimensions by arranging tubes in parallel passes separated by spacers. This three-dimensional configuration allows dense tube packing for high heat transfer capacity while maintaining adequate flow passages in the gaps between tube passes, enabling both high productivity and good flow characteristics simultaneously.
Solution Approach 2:
Multiple tube passes are nested within the same external footprint by folding the coil back on itself. This nesting arrangement maximizes heat transfer surface area within a compact volume while maintaining proper spacing between tubes in each pass, achieving high heat transfer capacity without restricting flow passages.
3Reliability
If spacers are added to maintain tube alignment, then heat transfer efficiency improves, but device complexity increases
Solution Approach 1:
Thin polymeric spacers with flexible yet structurally sufficient walls are used to maintain tube alignment. These thin-film spacers provide the necessary mechanical support to prevent tube contact and maintain spacing while adding minimal structural complexity to the overall coil assembly design.
Solution Approach 2:
The spacers are designed to perform multiple functions simultaneously: maintaining tube spacing, supporting tube weight, guiding assembly during manufacturing, and preventing tube contact at return bends. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity.
4Volume of stationary object
If return bends are tightly bundled to save space, then volume efficiency improves, but heat transfer deteriorates due to restricted flow and poor alignment
Solution Approach 1:
The spacers are pre-positioned at return bend locations before the tubes are bent into place. This preliminary placement of spacers ensures that proper alignment and spacing are established before the bending operation, preventing tube contact and maintaining flow passages even in the tightly bundled return bend regions, thus preserving heat transfer efficiency.
Solution Approach 2:
The return bends are designed with optimized curvature radii that balance space efficiency with flow requirements. The curved geometry is carefully engineered to maintain adequate spacing between adjacent return bends while achieving compact packaging, ensuring that heat transfer performance is not compromised by the curvature-induced bundling.
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 enhances heat transfer capacity and efficacy by maintaining tube alignment, reducing weight, and improving water distribution, resulting in increased efficiency and reduced operational costs compared to metal coil assemblies.
Implementation Method 1
the evaporation of the water on the external surface of the tubes of the coil cools the coil assembly by conduction and the internal heat transfer fluid inside the tubes by convection
Implementation Method 2
the evaporation of the water on the external surface of the tubes of the coil cools the coil assembly by conduction and the internal heat transfer fluid inside the tubes by convection
Implementation Method 3
the evaporation of the water on the external surface of the tubes of the coil cools the coil assembly by conduction
Data Source
AI summary
Coil assemblies for use in heat exchange applications are made using polymeric tubes, some with heat exchange and water redistribution media integral with the coil assembly and others with a water distribution subassembly integral with the coil assembly. One coil assembly includes at least two generally linear passes that are connected by return bends formed by folding an array of polymeric tubes. The passes have an array of at least two layers of polymeric tubes that pass through alignment holes in tube spacers only along the passes to maintain the tubes in substantially the same relative positional relationship to each other in the passes and in the return bends. Methods are explained for forming the coil assemblies and components, including the tube spacers and tube sheets to connect the coil assembly to inlet and outlet manifolds for the processing fluid flowing internally through the tubes.