Regenerative Cooling System for Heat Engine Efficiency
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Solution Overview
Problem
The existing Brayton regeneration cycle engines with centrifugal compressors and turbines have limited efficiency and adaptability, particularly in land transportation due to modest overall efficiency, narrow power and rotation speed range, and slow power modulation, making them unsuitable for cars and trucks, and the transfer-expansion and regeneration heat engine faces a dilemma between high efficiency with costly ceramics and lower efficiency with less expensive materials.
Innovation Solution
A regenerative cooling system that reduces the temperature of the internal walls of the expander cylinder and cylinder heads, allowing the use of less expensive materials while maintaining efficiency by incorporating a cooling chamber and flow control valves to manage gas circulation and heat transfer, enabling higher gas intake temperatures and improved energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If ceramic materials are used for the expander cylinder and cylinder heads to withstand high temperatures, then the engine can operate at higher gas intake temperatures and maintain higher efficiency, but the manufacturing cost increases significantly
Solution Approach 1:
The system divides the thermal management function into two separate systems: a regenerative heat exchanger system that recovers heat from exhaust gases to preheat intake gases, and a conventional cooling system that removes excess heat from the engine components. This segmentation allows the engine to operate with lower peak temperatures in the cylinder walls while maintaining high gas intake temperatures, enabling the use of less expensive materials.
Solution Approach 2:
The regenerative heat exchanger performs preliminary heating of the intake gases using waste heat from the exhaust gases before the gases enter the expander cylinder. This preliminary action reduces the temperature differential between the intake gases and the cylinder walls, allowing for lower operating temperatures and the use of less expensive materials while maintaining engine efficiency.
2Loss of energy
If the expander cylinder walls are maintained at high temperatures to prevent heat loss, then energy efficiency is improved, but material costs and manufacturing complexity increase
Solution Approach 1:
The system converts the waste heat that would otherwise be lost from the exhaust gases into a useful resource by using it to preheat the intake gases through the regenerative heat exchanger. This transforms the harmful heat loss into a beneficial preheating function, reducing the overall heat loss from the system and enabling the use of less expensive materials.
Solution Approach 2:
The regenerative heat exchanger recovers waste heat from the exhaust gases that would otherwise be discarded to the environment. By capturing and utilizing this waste heat for preheating intake gases, the system reduces overall energy loss and enables operation at lower cylinder wall temperatures with less expensive materials.
3Ease of manufacture
If conventional cooling systems are added to the regenerative heat engine, then the ability to use less expensive materials is improved, but the device complexity increases
Solution Approach 1:
The regenerative heat exchanger serves multiple functions: it preheats the intake gases using waste heat from exhaust gases, and it also acts as a heat source for the conventional cooling system. This multi-functionality allows the conventional cooling system to use the regenerative heat exchanger as its heat source, reducing the need for additional complex components and integrating the cooling function into the existing regenerative system.
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 regenerative cooling system enables the use of lower-cost materials for the transfer-expansion and regeneration heat engine without significantly reducing efficiency, allowing higher gas intake temperatures and improved final energy efficiency, decoupling material temperature resistance from gas temperature, and reducing manufacturing costs.
Implementation Method 1
a cooling chamber (79) which surrounds entirely or partly the gas expander (78) and/or the heat source (12) and/or a hot gas intake duct (19)
Implementation Method 2
leaving open a gas circulation space (80) between said chamber (79) on the one hand, and/or said expander (78) and/or said source (12) and/or said duct (19), on the other hand
Implementation Method 3
at least one regenerative heat exchanger (5) having a high-pressure regeneration duct (6) in which a working gas (81) circulates to be preheated there
Implementation Method 4
a chamber inlet port (82) which is directly or indirectly connected to the outlet of the gas expander (78) by a chamber inlet duct (84) whose effective cross section is regulated by a flow control valve (85)
Data Source
AI summary
The regenerative cooling system (100) is provided for a regenerative heat engine (1) and comprises a cooling chamber (79) which surrounds a gas expander (78), leaving open a gas circulation space (80) between said chamber (79) and said expander (78), a working gas (81) expelled from the gas expander (78) circulating in said space (80) before returning to a regenerative heat exchanger (5) where it is cooled, a large portion of the heat of said gas (81) being reintroduced into the thermodynamic cycle of the regenerative heat engine (1).