Buoyancy-Based Heat Engine Eliminates Compressors for Low-Temperature Power
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Solution Overview
Problem
Current heat engines are inefficient and costly for low-temperature, low-power applications, and existing renewable energy systems are not scalable or cost-effective for generating electricity from low-temperature heat sources, such as solar thermal and waste heat.
Innovation Solution
A thermodynamic vapor cycle heat engine that uses buoyancy force generated by a closed-loop vapor cycle with pressure changes induced by a thermal sink fluid, eliminating the need for compressors and turbines, allowing for efficient energy conversion and cost-effective power generation from low-temperature heat sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional heat engines are used for low temperature applications, then power generation is achieved, but energy conversion efficiency is low and capital cost per unit of power is high
Solution Approach 1:
The patent extracts and eliminates the compressor and turbine components from conventional heat engine systems. By removing these complex and expensive components, the system achieves low-temperature operation with reduced capital costs while maintaining energy conversion efficiency through alternative pressure control mechanisms using buoyancy forces.
Solution Approach 2:
The patent changes the operating parameters by operating at low temperature differentials (small ΔT) that are characteristic of waste heat sources. This parameter change enables the use of low-cost heat sources while maintaining efficient power generation through the eliminated compressor-turbine architecture.
2Power
If compressors and turbines are used to induce pressure changes, then power generation is achieved, but device complexity and capital cost increase
Solution Approach 1:
The patent removes compressors and turbines from the system, replacing them with a buoyancy-based pressure control mechanism. The mobile device's position in the thermal sink (submerged depth) controls cycle pressure through buoyant forces, eliminating complex mechanical compression and expansion components while maintaining power generation capability.
Solution Approach 2:
The patent replaces the mechanical compressor-turbine system with a buoyancy-based mechanical system. Pressure changes are achieved through the mobile device's vertical movement in the thermal sink fluid, using buoyant forces instead of mechanical compression and expansion, thereby reducing device complexity.
3Power
If continuous flow phase changes are used in turbines, then power is generated, but efficiency is reduced at low pressure ratios and temperatures due to flow losses
Solution Approach 1:
The patent employs periodic, discrete phase changes in the working fluid rather than continuous flow phase changes. The working fluid undergoes cyclic phase transitions (liquid-vapor-liquid) in the mobile device, synchronized with the device's periodic movement between high and low pressure regions, eliminating flow losses associated with continuous turbine operation at low pressures.
Solution Approach 2:
The patent maintains continuous useful action through the cyclic operation of the mobile device. The continuous movement of the mobile device between thermal sink regions ensures continuous buoyant force generation and continuous phase change cycles, maintaining efficient power generation without the flow losses that plague continuous turbine operation at low pressure ratios.
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
This solution provides improved energy conversion efficiency and reduced capital costs, enabling scalable and cost-effective electricity generation from low-temperature heat sources, including solar thermal energy, with minimal environmental impact and silent operation.
Implementation Method 1
The entire heat engine device transitions between regions of low and high pressure thermal sink fluid, in which thermal sink fluid applies pressure force against the refrigerant working fluid via a piston or bladder within the heat engine to create pressure changes in the cycle
Implementation Method 2
an external heat source provides thermal energy to the working fluid to induce a constant pressure phase change which generates boundary work in a discrete manner
Implementation Method 3
The device combines well-known thermodynamic and fluid dynamic principles with commercially available technologies in a unique and non-obvious manner, leveraging density changes occurring within a thermodynamic cycle to alter buoyancy of the heat engine device within a thermal sink fluid
Implementation Method 4
The shaft work used to generate power is generated through the conversion of this buoyant potential energy to mechanical energy through applied buoyant force which moves the entire heat engine device from high pressure region of the thermal sink fluid to the low pressure region of the thermal sink fluid
Implementation Method 5
an external heat source provides thermal energy to the working fluid to induce a constant pressure phase change
Data Source
AI summary
Systems and methods to convert low temperature solar thermal or waste heat sources for electric power generation, by integrating available technologies with a unique, efficient combined cycle. The device consists of mobile pods immersed within a thermal sink fluid reservoir. A vapor cycle converts thermal energy to buoyant potential energy by inducing density and volume changes of the mobile pods through discrete phase changes of a refrigerant working fluid. Buoyant potential energy is then converted to electrical power through motion of the entire pod within a thermal sink pressure gradient.