OTEC Buoyancy Plug Control for Autonomous UUV Diving
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Solution Overview
Problem
Unmanned underwater vehicles (UUVs) face challenges in prolonged operation due to power supply limitations, as traditional methods like tethers restrict range and autonomy, and fuel cells require large space and packages.
Innovation Solution
A tactical maneuvering ocean thermal energy conversion buoy system that uses fluid pressure differences generated by temperature variations between surface and deep ocean water to power an actuator and hydraulic system, allowing for frequent dives and autonomous operation without electrical power storage, leveraging CO2 and hydraulic fluid to control buoyancy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a tether is used to supply power to the UUV, then power supply is ensured, but the UUV's range and autonomy are limited
Solution Approach 1:
The UUV generates its own power through an onboard Ocean Thermal Energy Conversion (OTEC) system that utilizes temperature differences between surface and deep ocean water to drive a power generation cycle, eliminating the need for external power sources or tethers and enabling autonomous operation
Solution Approach 2:
The system changes the physical state of a working fluid through temperature variations, using warm surface water to evaporate the fluid and cold deep water to condense it, creating pressure differentials that drive the power generation mechanism
2Use of energy by moving object
If fuel cells are used to generate power in the UUV, then power supply is improved, but the vehicle requires large packages and substantial space
Solution Approach 1:
The UUV harnesses ambient thermal energy from the ocean environment itself to generate power, eliminating the need for carrying fuel cells or other power generation equipment that would occupy significant vehicle volume
Solution Approach 2:
The system extracts useful energy directly from the ocean's thermal gradient, removing the need for onboard fuel storage and power generation equipment by utilizing the environment as the energy source
3Duration of action of moving object
If traditional power supply methods are used, then the UUV can operate, but prolonged operation is limited
Solution Approach 1:
The OTEC system enables continuous power generation by maintaining a constant thermal exchange between surface and deep ocean water, allowing the UUV to operate indefinitely as long as the temperature gradient exists, eliminating the need for periodic recharging or refueling
Solution Approach 2:
The system continuously cycles the working fluid through phase changes driven by temperature variations, converting thermal energy to mechanical work and then to electrical energy in an ongoing process that sustains prolonged operation
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
Enables frequent and efficient crossing of ocean sound channels, enhancing mobility and endurance by utilizing thermal energy for buoyancy control, reducing energy loss mechanisms and allowing for continuous surveillance operations.
Implementation Method 1
flows of the refrigerant between the tanks and the spaces can be created based on a pressure differential, such as a pressure differential created by a temperature difference between the tanks
Implementation Method 2
a buoyancy plug configured to change a position inward or outward with respect to a body of a vehicle in connection with the amount of the hydraulic fluid in the hydraulic cylinder, wherein movements of the buoyancy plug are fluidly coupled to movements of the actuator and hydraulic pistons, and wherein the position of the buoyancy plug affects a buoyancy of the vehicle
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
A system includes a first jacket (202) that contains water and a first tank (206) storing a first fluid under pressure. A second jacket (204) contains water and a second tank (208) storing a second fluid under pressure. An actuator cylinder (214) defines a space that receives the fluids from the first and second tanks. The actuator cylinder includes an actuator piston (234) that divides the space into a first volume for the first fluid and a second volume for the second fluid. A hydraulic cylinder (216) includes a hydraulic piston (236) configured to move and change an amount of hydraulic fluid (218) in the hydraulic cylinder, where the hydraulic piston is fixedly coupled to the actuator piston. A buoyancy plug (108) changes a position in connection with the amount of the hydraulic fluid in the hydraulic cylinder, where the position of the buoyancy plug affects a buoyancy of a vehicle (100).