Turbulators in enhanced tubes
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Solution Overview
Problem
Heat exchangers in HVAC systems face inefficiencies in heat transfer, particularly at low Reynolds numbers, where existing surface features alone do not significantly enhance heat exchange efficiency.
Innovation Solution
Combining external surface features like crushed fins with internal surface features such as rifled helices and turbulators to create turbulence and enhance heat transfer coefficients across a wider range of fluid flow regimes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If only one type of surface feature (external or internal) is used on heat transfer tubes, then the device complexity is lower, but the heat transfer coefficient enhancement is limited
Solution Approach 1:
The patent combines both external surface features (such as fins, corrugations, or dimples on the outer surface) and internal surface features (such as ribs, helical grooves, or turbulators on the inner surface) on the same heat transfer tube. This merging of multiple surface feature types creates synergistic effects that enhance heat transfer coefficients by 15-30% compared to using single-type features, while managing the increased manufacturing complexity through integrated tube design
2Productivity
If surface features are added to enhance heat transfer, then the heat transfer coefficient improves, but the pressure drop increases
Solution Approach 1:
The patent applies different surface feature configurations to different locations and surfaces of the heat transfer tube. External features like fins or corrugations are applied on the outer surface to enhance convection, while internal features like ribs or helical grooves are strategically placed to enhance turbulence without excessive pressure drop. This localized application of different surface qualities allows optimization of heat transfer while managing pressure losses in different flow regions
Solution Approach 2:
The patent optimizes geometric parameters of surface features including fin height, corrugation amplitude, rib spacing, and groove depth to achieve the desired balance between heat transfer enhancement and pressure drop. By carefully selecting and adjusting these parameters, the system achieves 15-30% heat transfer coefficient improvement while keeping pressure drop increases within acceptable limits for the HVAC application
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 combination achieves a 15% to 30% improvement in overall heat transfer coefficient compared to heat transfer tubes with only one type of surface feature, expanding the operational range and efficiency of HVAC systems, especially in low temperature applications.
Implementation Method 1
cavities can be defined between fins. A top of the fin can have one or more of the notches, and the fin can be crushed or otherwise bent to create from the notches one or more side cavities on the fin
Implementation Method 2
external surface feature(s) can include a fin structure that has been crushed. The fin structure has fins with notches
Implementation Method 3
internal surface feature(s) can include a rib structure where, in certain circumstances, the rib structure may be rifled into a helical configuration
Implementation Method 4
the rifles may be arranged in a cross hatched configuration from two or more helixes (or helices) that cross over each other
Implementation Method 5
A turbulator is installed on the inside (i.e. tube side) of the enhanced tube... The combination of the turbulator and the enhanced tube can improve heat exchange efficiency when the fluid flow has a relatively low Reynolds number
Data Source
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AI summary
A heat exchange tube combines an external surface feature, for example having crushed fins and cavities, which can have very high boiling enhancement characteristics, with an internal surface feature, for example having high performing intersecting helices, e.g. "cross hatched" with an intersecting helix angle. The new tube can provide a high performing tube in a shell and tube evaporator that can be relatively smaller, more efficient, and that can use relatively lower refrigerant charge.