Multi-Temperature Double-Acting Piston for High-Temperature Sealing
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Solution Overview
Problem
Existing Brayton cycle regenerative engines face inefficiencies due to the limitations of centrifugal compressors and turbines, and volumetric piston expanders, which either operate at low efficiency or require materials that cannot withstand high temperatures for effective sealing, leading to thermodynamic inefficiencies and material degradation.
Innovation Solution
A multi-temperature double-acting piston design that uses silicon carbide for high-temperature components and eliminates the need for fluid cushion sealing devices, allowing for efficient gas expansion and reduced heat losses, while maintaining the piston and cylinder at different temperatures for optimal operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If high-temperature materials are used to maintain cylinder walls close to gas temperature for high efficiency, then thermodynamic efficiency is improved, but material availability and cost are worsened
Solution Approach 1:
The piston is divided into multiple temperature zones: hot caps (upper and lower) made of silicon carbide that contact hot gases, and a cold body made of aluminum alloy that contacts cooling channels. This segmentation allows each part to be optimized for its specific temperature environment, achieving high thermodynamic efficiency while using readily available materials.
Solution Approach 2:
The piston combines silicon carbide (high-temperature resistant ceramic) for the hot caps with aluminum alloy (lightweight, thermally conductive metal) for the cold body. This composite structure enables the piston to withstand high temperatures where needed while maintaining overall thermal management efficiency and using materials that are both high-performance and practically available.
2Reliability
If conventional piston sealing with oil film is used, then lubrication is achieved, but the oil film cannot withstand high temperatures above 160°C
Solution Approach 1:
The piston separates sealing functions from high-temperature zones. The cold body with its lower temperature (maintained by cooling channels) houses the sealing rings and oil film, while the hot caps are thermally isolated from these sealing components. This allows conventional oil-film sealing to function reliably without exposure to extreme temperatures.
Solution Approach 2:
The cold body acts as a thermal intermediary, protecting the oil-film sealing system from high temperatures by providing a cooler environment through integrated cooling channels. The thermal barrier created by this intermediary structure allows conventional lubrication to operate effectively despite the hot gas environment.
3Reliability
If regenerative cooling systems are implemented to maintain low cylinder temperatures, then sealing is improved, but system complexity and weight increase
Solution Approach 1:
The cooling function is merged directly into the piston body structure itself. The cold body contains integrated cooling channels that circulate coolant, eliminating the need for separate regenerative cooling systems. This integration maintains effective sealing temperatures while reducing overall system complexity and removing redundant components.
Solution Approach 2:
The piston is self-cooling through its own integrated cooling channels in the cold body. The structure provides its own thermal management capability without requiring external regenerative cooling systems, thereby simplifying the overall engine architecture while maintaining reliable sealing conditions.
4Temperature
If silicon carbide is used for hot caps, then high-temperature resistance is improved, but material cost is increased
Solution Approach 1:
Silicon carbide is used only locally in the hot caps where high-temperature resistance is critically needed for contact with hot gases. The rest of the piston (the cold body) uses more cost-effective aluminum alloy. This localized application of expensive high-performance material achieves the necessary temperature resistance while controlling overall material costs.
Solution Approach 2:
The design changes the material selection based on local temperature parameters: silicon carbide for high-temperature zones (hot caps) and aluminum alloy for lower-temperature zones (cold body). This parameter-based material selection optimizes both performance and cost by matching material properties to thermal environment requirements.
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 design achieves thermodynamic efficiencies exceeding those of diesel engines, with reduced material costs, weight, and energy consumption, suitable for applications in transport and stationary power generation.
Implementation Method 1
lesdits dits buts et dits fonds étant faits en un matériau résistant aux hautes températures, préférentiellement en carbure de silicium
Implementation Method 2
le corps de piston étant fait en alliage d'aluminium
Implementation Method 3
disposant de moyens de jointicité en friction avec le cylindre
Data Source
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AI summary
The invention relates to a multi-temperature double-acting piston (201), which comprises a peripheral sealing ring (220), a lower hot crown (226) and/or an upper hot crown (232), and translates in a cold cylinder (204) of a heat engine (202) which has a lower yoke (213) and an upper yoke (214), said piston (201) comprising a central piston pin (210), the lower piston rod (211) of which passes through the lower yoke (213) to be connected to power transmission means (205) housed in a transmission housing (206), and the upper piston rod (212) of which passes through the upper yoke (214) in order to open into a cooling and piston lubrication chamber (217), wherein a lubrication-cooling gallery (227) arranged in said pin (210) places said chamber (217) in communication with said housing (206) via an internal piston volume (228).