Flexible Multi-Sided CNG Container for Space Optimization
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Solution Overview
Problem
Current gas containment solutions, such as rigid cylindrical containers, are heavy and inefficient in utilizing cargo space, leading to high transportation costs and limited capacity due to their circular cross-sections and high self-weight, which restricts the use of large diameter high-pressure CNG tanks in land and marine transport.
Innovation Solution
A multi-sided container with a non-circular cross-section, featuring flexible sides and rounded corners, is used in conjunction with an external support system to allow center-span deflection without plastic deformation, optimizing the use of cargo space and reducing the weight of the containment system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If rigid cylindrical containers with circular cross-section are used to store pressurized gas, then the containers can resist pressure-induced hoop stresses, but the containers become heavy and inefficient in utilizing cargo space
Solution Approach 1:
The patent employs thin-walled flexible containers with non-circular cross-sections that can deflect under pressure rather than relying on thick rigid walls. The flexibility of the container walls allows them to accommodate pressure-induced deformations without requiring heavy structural reinforcement, thereby reducing container weight while maintaining pressure containment capability.
Solution Approach 2:
The patent transitions from static rigid cylindrical containers to dynamic flexible containers that can change shape under pressure. The non-circular cross-section allows the container to deflect and adapt its shape in response to internal pressure, converting the static strength requirement into a dynamic response that reduces material requirements and overall weight.
2Strength
If rigid cylindrical containers with circular cross-section are used, then the containers can maintain structural integrity under pressure, but they do not efficiently fill available storage and transport space
Solution Approach 1:
The patent employs non-circular cross-sections (such as rectangular, triangular, or other polygonal shapes) instead of traditional circular sections. These asymmetric shapes can be optimized to fit specific cargo space geometries more efficiently, allowing better utilization of available storage and transport volume while maintaining adequate structural integrity through the flexible wall design.
Solution Approach 2:
The flexible nature of the container walls enables them to conform to the available cargo space geometry and to deform under pressure without compromising integrity. This flexibility allows the container to maximize its volume utilization within constrained transport spaces while accommodating pressure-induced shape changes.
3Stress or pressure
If high-strength steel cylinders are used to contain pressurized gas, then the containers can withstand high pressures, but the ratio of cargo mass to container mass is reduced
Solution Approach 1:
The patent uses thin-walled flexible containers that can withstand high pressures through elastic deformation rather than relying on thick high-strength steel walls. This approach dramatically reduces the container mass while maintaining the ability to contain high-pressure gases, thereby significantly improving the cargo mass to container mass ratio.
Solution Approach 2:
The patent changes the fundamental parameter of container wall rigidity, transitioning from rigid high-strength steel to flexible thin-walled materials. This parameter change allows the container to respond to high pressures through controlled deformation rather than requiring massive structural support, thus reducing container weight and improving the cargo-to-container mass ratio.
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 enables efficient storage and transport of pressurized fluids by maximizing the utilization of available space and reducing the weight of the containment system, achieving higher mass ratios of cargo to container while maintaining structural integrity under high pressures and low temperatures.
Implementation Method 1
The container is adapted to allow the sides to expand outwardly by at least the amount of the wall thickness while the container contains the fluid cargo at the specified normal operating pressure
Implementation Method 2
The container is used in conjunction with an external support system that limits the outward deflection of the side walls of the container while the container contains the pressurized fluid cargo at the specified normal operating pressure, with no support being provided to the rounded corner of the container, thereby enabling centre-span deflection of the side walls without plastic deformation thereof
Data Source
Figure 1A~2
Figure 3A~4B
Figure 5A~5B
AI summary
A container and a method for storage and/or transport of a compressed fluid such as compressed natural gas are provided. The container has a pair of opposing heads and a wall section between the heads, the wall section defining a square cross-section comprising substantially planar sides joined together by rounded corners. The container is designed for the side walls to deflect outwardly while under pressure, but to be supported externally by a support system that restricts outward expansion of the side walls. The support system can be provided as the walls of a cargo hold in a marine or land transport vessel, an ISO shipping container or an underground shaft. Multiple containers can be located side by side in the external support system so that the sides of adjacent containers rest against each other for support while under pressure. In one embodiment, a container comprises an outside tank and a flexible membrane tank inside the outside tank, an annular space being defined in between, where a first fluid is charged into the membrane tank and a second fluid is charged into the annular space in order to discharge the first fluid. In another embodiment, a long tube having a square cross-section is coiled in a support structure and made gas-tight for holding a compressed fluid. The walls of the tube would tend to expand while under pressure, but adjacent coils and the support structure limit the expansion.