Stirling Heat Machine Impeller Design for Low-Temperature Efficiency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing Stirling engines face inefficiencies due to small heat exchange areas, substantial mechanical resistance, and adverse heat transfer via the casing, leading to low efficiency, especially when using low-temperature energy sources.
Innovation Solution
A Stirling cycle heat machine design where working agent compression and decompression occur exclusively in working chambers, with a one-direction flow between chambers at constant volume, utilizing identical vaned impellers in hot and cold chambers connected by conduits to minimize volume changes and maximize heat exchange efficiency, allowing for low-temperature energy sources like solar or geothermal energy to be effectively utilized.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the volume of flow elements (heater and cooler) is minimized to achieve intensive pressure buildup, then pressure buildup intensity improves, but heat exchange area becomes insufficient leading to low efficiency
Solution Approach 1:
The engine is divided into multiple working spaces (at least two) arranged radially around the impeller, with each working space having dedicated flow elements (heaters and coolers). This segmentation allows each flow element to be compact while the collective arrangement provides sufficient total heat exchange area, resolving the contradiction between minimized volume and sufficient heat exchange area.
2Area of stationary object
If external heat exchangers are used to increase heat exchange area for low-temperature sources, then heat exchange area increases, but device complexity increases
Solution Approach 1:
The flow elements (heaters and coolers) are integrated directly into the working spaces within the engine structure, eliminating the need for separate external heat exchangers. The heaters and coolers are positioned to directly contact the working agent in each working space, combining the heat exchange function with the working space structure itself, thus increasing heat exchange area without adding external components.
3Device complexity
If heat transfer via casing is used for simplicity, then device complexity decreases, but heat transfer efficiency becomes adverse leading to low efficiency
Solution Approach 1:
The heat exchange function is extracted from the casing and relocated to dedicated flow elements (heaters and coolers) positioned within each working space. This allows direct thermal contact between the heat exchange elements and the working agent, eliminating adverse heat transfer through the casing while maintaining structural simplicity through integrated design.
4Loss of energy
If mechanical resistance is reduced to improve efficiency, then efficiency improves, but ability to utilize low-temperature energy sources decreases
Solution Approach 1:
The impeller rotates dynamically to sequentially position the working spaces relative to the heaters and coolers, enabling continuous cyclic operation. This dynamic operation allows the engine to maintain low mechanical resistance through efficient gas flow management while utilizing low-temperature heat sources, as the continuous motion prevents pressure losses and maintains smooth operation at lower temperature differentials.
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 design enhances mechanical energy production and efficiency by minimizing mechanical resistance and optimizing heat transfer, enabling high-efficiency operation with low-temperature energy sources while maintaining constant volume transport between chambers.
Implementation Method 1
A method of flow of a working agent in a heat machine based on the Stirling cycle
Implementation Method 2
In order to achieve the heat flow the working gas needs to be alternately heated and cooled
Implementation Method 3
optimizing heat transfer
Implementation Method 4
an impeller fitted with vanes which are guided along the inner surface of the cold chamber
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A method of flow of the working agent in a heat machine based on the Stirling cycle is characterized in that the working agent compression and decompression processes take place exclusively in the working chambers, and once the compression and decompression processes are complete, the entire working agent leaves the working chambers, where the transport between the said working chambers takes place at constant volume. A heat machine based on the Stirling cycle comprising a cold chamber (2) and a hot chamber (1), placed inside of which are impellers (12, 21) fitted with vanes (13, 20) guided along the inner surfaces of the chambers. The impellers (12, 21) are fitted on a common shaft (4) positioned in the chamber axis. The volumes of the working spaces (14, 19) formed between the said vanes (13, 20) change as the impeller rotates, and the total combined volume of the working spaces of the hot and cold chambers does not change when the spaces are combined, where the compression and decompression of the working agent takes place exclusively in the respective chamber.