Thermal-Difference Piston Generator for Compact UUV Power
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Solution Overview
Problem
Existing power generation systems for unmanned underwater vehicles (UUVs) face limitations in providing adequate power for prolonged operation, with tethered systems restricting range and autonomy, while alternative methods like expanding wax and fuel cells offer insufficient power capacity or require large space.
Innovation Solution
A power generation system based on thermal differences using slow-motion high-force energy conversion, utilizing refrigerant tanks with temperature-induced pressure differentials to drive a piston, which is converted into electrical power through a chain drive or ball screw mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If tethered power supply is used, then power can be supplied to UUV, but range and deployment freedom are limited
Solution Approach 1:
The UUV generates its own power through onboard power generation systems (fuel cells, thermal energy conversion systems, or expanding wax mechanisms) rather than relying on external tethered power supply, enabling autonomous operation and extended range while maintaining power capability
2Power
If expanding wax based on absorbed heat is used, then power is generated, but power amount is very small (less than 200 W)
Solution Approach 1:
The system utilizes phase transitions of refrigerant (liquid-gas transitions) in thermal energy conversion systems and expanding wax mechanisms to generate power, where the phase change process absorbs and releases thermal energy to drive mechanical motion and electricity generation
Solution Approach 2:
The system changes physical parameters such as temperature differentials, pressure differentials, and thermal conductivity properties to optimize power generation output from thermal energy conversion systems and expanding wax mechanisms
3Power
If fuel cells are used, then power is generated, but large packages and substantial space are required
Solution Approach 1:
The power generation system is divided into modular components including separate tanks for hot and cold refrigerant, individual heat exchange units, and distributed expanding wax mechanisms, allowing flexible arrangement and reduced overall volume
Solution Approach 2:
The system uses phase transitions of refrigerant and expanding wax materials to generate power through compact thermal energy conversion mechanisms, eliminating the need for large fuel cell packages while maintaining power generation capability
4Power
If thermal energy conversion systems are used, then power can be generated, but system complexity increases
Solution Approach 1:
The system merges thermal energy conversion mechanisms with expanding wax power generation and refrigerant cycle systems into an integrated power generation platform, reducing overall system complexity while maintaining or enhancing power output capability
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
Generates a significant amount of electrical power efficiently with fewer components and reduced size/weight, capable of producing 1 kW of continuous power with 25 to 400 WHr capacity using carbon dioxide as refrigerant, even with small temperature differentials.
Implementation Method 1
a first tank configured to hold a refrigerant under a first pressure and having a first temperature and a second tank configured to hold the refrigerant under a second pressure and having a second temperature
Implementation Method 2
pressure differential, such as a pressure differential created by a temperature difference between the tanks
Implementation Method 3
power generation systems based on thermal differences using slow-motion high-force energy conversion
Implementation Method 4
at least one generator configured to generate electrical power based on movement of the piston
Data Source
Figure 1A~1D
Figure 2A~2C
Figure 3
AI summary
An apparatus includes first and second tanks (402-404, 1002-1004) each configured to receive and store a refrigerant under pressure. The apparatus also includes a cylinder (406, 1006) defining a space configured to receive the refrigerant from the first and second tanks. The apparatus further includes a piston (420, 1020) passing into the cylinder and having a head (422), where the head divides the space within the cylinder into a first volume for the refrigerant from the first tank and a second volume for the refrigerant from the second tank. In addition, the apparatus includes a converter (408, 1008) configured to translate linear movement of the piston into rotational motion and a generator (604, 1062) configured to produce electrical power based on the rotational motion.