Sealed Gimbal for OTEC Cold Water Pipe
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Solution Overview
Problem
Existing Cold Water Pipes (CWP) for Ocean Thermal Energy Conversion (OTEC) facilities face challenges in maintaining a seal and supporting structural forces at large diameters and high differential pressures, especially during gimballing at angles of up to 20 degrees, which is not effectively addressed by current technologies.
Innovation Solution
A sealed gimbal system with a centrally-located passive rotating latch and spherical elastomeric flexible joint, combined with overlapping spherical shells and rolling diaphragm seals, allows for passive vertical latching and unlatching, accommodating high axial and radial loads, and angular excursions while maintaining a seal at high pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional gimbal seal is used for small diameter pipes, then sealing is effective, but it cannot accommodate large radial excursions and high pressures for large diameter CWP
Solution Approach 1:
The seal is divided into multiple segments arranged circumferentially around the pipe. Each segment can independently deflect radially to accommodate large excursions while maintaining contact with the pipe surface. The segments are connected by hinges that allow radial movement while preserving the sealing function across the entire circumference.
Solution Approach 2:
The seal transitions from a static rigid structure to a dynamic flexible structure. The segmented design with hinges enables the seal to dynamically adapt its shape in response to radial excursions, maintaining sealing contact throughout the range of motion. The seal actively follows the pipe's radial movements rather than resisting them.
2Stability of the object's composition
If the gimbal connection is kept near the center of the CWP, then structural stability is improved, but the seal must withstand high pressure at the outer diameter while accommodating large radial excursions
Solution Approach 1:
The seal employs flexible membrane elements that can deform under pressure while maintaining their sealing function. These flexible shells conform to the pipe surface and can accommodate radial excursions without failing under the high differential pressures present at the outer diameter of the large diameter pipe.
Solution Approach 2:
The seal design incorporates features that distribute and counterbalance the high differential pressures acting on the outer diameter. The segmented structure with hinges creates a mechanism where pressure forces are balanced across multiple elements, preventing any single point from experiencing overwhelming stress.
3Stress or pressure
If a rigid seal structure is used, then it can withstand high pressure, but it adds friction and stress to the CWP during gimballing
Solution Approach 1:
The flexible seal structure eliminates rigid contact surfaces that would generate high friction during gimballing. The flexible membranes conform to the pipe surface and move with it, creating minimal resistance to radial excursions and reducing stress concentrations that would occur with rigid structures.
Solution Approach 2:
The seal transitions from a static rigid structure to a dynamic flexible structure that moves with the pipe during gimballing. This dynamic adaptation minimizes relative motion and friction between seal and pipe surfaces, reducing the harmful forces generated during angular excursions.
4Reliability
If conventional gimballing connections are used for SCR, then they can seal fluids under pressure, but they are not suitable for the order-of-magnitude larger diameter of OTEC CWP
Solution Approach 1:
The seal is divided into multiple segments arranged circumferentially around the pipe. Each segment can independently deflect radially to accommodate large excursions while maintaining contact with the pipe surface. The segments are connected by hinges that allow radial movement while preserving the sealing function across the entire circumference.
Solution Approach 2:
The segmented flexible seal design creates a universal solution that can be scaled to large diameters while maintaining the sealing principles proven effective in smaller applications. The modular nature of the segmented design allows the same basic principle to be applied across different diameter scales.
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 ensures effective sealing and support of the CWP at high differential pressures, minimizes flow restrictions, and is installable without surface divers, with components that are inexpensive, simple, and durable, capable of lasting over 20 years with minimal friction and stress addition.
Implementation Method 1
rolling diaphragm seals that move along the CWP surface to seal differential pressure
Implementation Method 2
spherical elastomeric flexible joint
Implementation Method 3
The gimbal seal must withstand differential pressures of approximately 1.7 bar
Implementation Method 4
The CWP is subjected to... hydraulic pressure differentials
Implementation Method 5
passive vertical latching and unlatching of the CWP
Implementation Method 6
centrally-located passive rotating latch
Implementation Method 7
spherical elastomeric flexible joint
Implementation Method 8
spherical elastomeric flexible joint
Data Source
AI summary
A gimbal that provides for passive vertical latching and unlatching of a Cold Water Pipe (CWP) in a floating vessel such as an Ocean Thermal Energy Conversion (OTEC) facility is sealingly connected to a cold water sump on the floating vessel. The CWP gimbal is capable of reacting all static and dynamic forces of the suspended CWP at angles on the order of +/â20 degrees while remaining sealed at high differential pressures.