Controlled Wrinkle Bends for High-Pressure Heat Exchanger Tubes
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The conventional tube bending process for serpentine circuit tubes in indirect heat exchanger pressure vessels is complex and often requires internal mandrels, which increases costs, cycle time, and the risk of leaks, while also limiting the length of the tubes and causing thinning of the outside wall, compromising the tube's ability to withstand high pressures.
Innovation Solution
The use of controlled wrinkled bends with alternating ridges and grooves in the serpentine circuit tubes, which reduces bend complexity and allows for mandrel-free bending, enhancing the tube's structural integrity and reducing fluid pressure drop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional tube bending process with internal mandrels is used, then bends can be formed in serpentine circuit tubes, but the process complexity increases, manufacturing costs increase, and cycle time increases
Solution Approach 1:
The patent removes the internal mandrel from the bending process entirely. By using an external bending mechanism that applies force from the outside of the tube, the complex internal mandrel system is extracted and eliminated, simplifying the overall bending process while still achieving the desired bend geometry in the serpentine circuit tubes
Solution Approach 2:
The patent introduces a bending tool or die as an intermediary external device that facilitates the bending process. This external bending mechanism acts as a mediator between the applied force and the tube, enabling controlled bending without requiring internal mandrels, thus reducing process complexity while maintaining manufacturing capability
2Ease of manufacture
If internal mandrels are used in tube bending, then bends can be formed, but manufacturing costs increase and cycle time increases
Solution Approach 1:
By removing the internal mandrel from the process, the patent eliminates the time-consuming steps of inserting, positioning, and removing the mandrel during bending. The external bending mechanism performs the entire bending operation in a single continuous action, significantly reducing the manufacturing cycle time while maintaining the ability to form accurate bends
Solution Approach 2:
The patent skips the intermediate steps associated with internal mandrel usage (insertion, positioning, support during bending, removal). The external bending mechanism rushes through the bending operation in a single streamlined process, eliminating unnecessary time-consuming steps while still achieving the required bend geometry
3Ease of manufacture
If internal mandrels are used in tube bending, then bends can be formed, but the risk of leaks increases
Solution Approach 1:
By extracting and removing the internal mandrel from the bending process, the patent eliminates the potential failure points associated with mandrel-tube interfaces. Without internal mandrels, there are no interfaces where sealing issues or improper support could cause wall thinning or defects that lead to leaks, thereby improving the reliability of the bent tubes
Solution Approach 2:
The patent converts the potential harm of complex internal mandrel systems (which can cause wall thinning, improper support, and leak points) into a benefit by using a simpler external bending mechanism. This external approach avoids all the problems associated with internal mandrels while still achieving the necessary bend formation, effectively turning the elimination of a complex system into a reliability improvement
4Ease of manufacture
If conventional bending is used, then bends can be formed, but the outside wall thins and the tube's ability to withstand high pressures is compromised
Solution Approach 1:
The patent uses an external bending mechanism as an intermediary that applies controlled force from the outside of the tube. This external approach acts as a mediator that distributes bending stresses more uniformly across the tube wall, preventing the localized wall thinning that occurs with internal mandrels while still achieving the desired bend geometry, thereby maintaining the tube's pressure withstanding capability
Solution Approach 2:
The patent changes the bending parameters by switching from an internal mandrel approach to an external bending approach. This parameter change in the bending methodology alters the stress distribution during bending, preventing wall thinning and maintaining the structural integrity and pressure withstanding capability of the bent tubes while still enabling bend formation
Data Source
AI summary
In one aspect of the present disclosure, an indirect heat exchanger pressure vessel is provided that includes an inlet header to receive a pressurized working fluid, such as water, glycol, ammonia, and/or CO2. The indirect heat exchanger pressure vessel includes an outlet header to collect the pressurized working fluid and a serpentine circuit tube connecting the inlet and outlet headers. The serpentine circuit tube permits the pressurized working fluid to flow from the inlet header to the outlet header. The serpentine circuit tube includes runs and a return bend connecting the runs. The return bend has a controlled wrinkled portion comprising alternating ridges and grooves. The alternating ridges and grooves strengthen the return bend and permit the indirect heat exchanger pressure vessel to facilitate working fluid heat transfer at a high internal operating pressure.