Reciprocating Heat Engine Hot Cylinder Head Cold Cylinder Design
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Solution Overview
Problem
Regenerative Brayton cycle engines with centrifugal compressors and turbines have limited thermodynamic efficiency, and replacing them with piston machines is challenging due to high-temperature requirements and lubrication issues, leading to inefficiencies and material limitations.
Innovation Solution
A reciprocating heat engine with a hot cylinder head and cold cylinder design that uses conventional piston sealing means and silicon carbide materials to maintain high temperatures while minimizing heat losses and ensuring durable sealing, eliminating the need for fluid cushion sealing devices and regenerative cooling systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the internal walls of the expansion valve are maintained at high temperature to maximize thermodynamic efficiency, then the thermodynamic efficiency is improved, but the lubrication of sealing segments becomes impossible
Solution Approach 1:
The invention divides the expansion valve into two distinct temperature zones: the cylinder head and crown are maintained at high temperature (900-1000°C) to maximize thermodynamic efficiency, while the cylinder is cooled to low temperature (50-100°C) to enable lubrication. This segmentation allows each component to operate at its optimal temperature without compromising the other.
Solution Approach 2:
Different parts of the expansion valve are assigned different thermal properties: the cylinder head and crown have high heat resistance for efficiency, while the cylinder has high heat dissipation capability for lubrication. This local differentiation of thermal characteristics resolves the contradiction between high-temperature efficiency requirements and low-temperature lubrication requirements.
2Device complexity
If conventional piston sealing means are used in high-temperature expansion valves, then the sealing is simplified, but the sealing segments would burn due to high temperature
Solution Approach 1:
The sealing system is segmented into two functional zones: the piston and sealing segments operate in the cooled cylinder at low temperature where conventional lubrication is effective, while the cylinder head and crown operate at high temperature for efficiency. This spatial segmentation allows conventional sealing means to function reliably without burning.
Solution Approach 2:
The cooled cylinder acts as an intermediary thermal barrier between the high-temperature working gases and the conventional sealing segments. By maintaining the cylinder at low temperature, it protects the sealing segments from direct exposure to high-temperature gases, enabling them to operate reliably with conventional lubrication.
3Duration of action of moving object
If centrifugal compressors and turbines are used in regenerative Brayton cycle engines, then the continuous operation is improved, but the thermodynamic efficiency remains limited
Solution Approach 1:
The invention replaces the centrifugal compressor and turbine system with a reciprocating piston-based expansion valve system. This substitution enables the regenerative Brayton cycle to achieve higher thermodynamic efficiency by utilizing the high-temperature/low-pressure and low-temperature/high-pressure states more effectively, while maintaining continuous operation through the cyclic reciprocating motion.
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 achieves higher thermodynamic efficiency, exceeding that of diesel engines, with reduced energy consumption and weight, while using abundant and inexpensive materials, and minimizing heat losses and energy required to reach operating temperatures.
Implementation Method 1
the inner walls of said cylinder head and of said crown are maintained at a high temperature so as to limit the cooling of the hot gases in contact therewith
Implementation Method 2
the inner surface of said cold cylinder is cooled so as to maintain it at a sufficiently low temperature such that the lubricant film does not age prematurely, coke or burn
Implementation Method 3
lubricating means which form a lubricant film which is interposed between the cold cylinder and the piston
Implementation Method 4
a piston... moving in translation... directly or indirectly connected by power transmission means... to at least one rotary or reciprocating power output shaft
Data Source
AI summary
Reciprocating heat engine with hot cylinder head and cold cylinder includes a cooled cylinder casing which receives a cold cylinder covered with a lubricant film and in which a piston connected to power transmission moves in translation to form a variable-volume hot chamber with a hot cylinder head which is held applied but free to expand on the cylinder casing by cylinder head applying unit, while a hot crown is interposed between the chamber and the piston and is held applied but free to expand on the piston by crown applying unit, the piston including a cooled piston sealing ring which has a piston sealing unit.