Closed Loop Scroll Expander for External Heat Engines
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Solution Overview
Problem
Current internal combustion engines face inefficiencies, limited power density, and environmental constraints due to friction, heat loss, and combustion timing issues, particularly at varying altitudes and air densities, and existing external combustion engines are bulky and heavy due to isothermal compression requirements.
Innovation Solution
A closed loop regenerative heat engine using a scroll expander with an external heat source, capable of operating in Rankine, Brayton, or supercritical cycles, utilizing carbon dioxide as a working fluid to achieve high efficiency and power density, independent of atmospheric conditions, with a compact and lightweight design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If internal combustion engines are used, then power conversion efficiency is achieved, but friction, heat loss, and combustion timing limitations reduce efficiency to 20-30%
Solution Approach 1:
The patent extracts the combustion process from the power conversion system by using an external heat source (combustion chamber separate from the engine block) to heat the working fluid. This separates the heat generation function from the power conversion function, eliminating the efficiency losses associated with internal combustion timing and friction while maintaining high energy efficiency.
2Power
If internal combustion engines operate at high altitude, then power generation is maintained, but atmospheric density reduction decreases power availability
Solution Approach 1:
The patent changes the working fluid parameters by using carbon dioxide in a closed-loop system where pressure and temperature are independently controlled. This allows the engine to maintain optimal operating parameters regardless of atmospheric density, enabling consistent power output from sea level to 50,000 feet altitude.
3Loss of energy
If external combustion engines are designed for high efficiency, then thermodynamic efficiency is improved, but isothermal compression requirements make them bulky and heavy
Solution Approach 1:
The patent employs a scroll expander with dynamic sealing that allows the working fluid to expand dynamically without requiring complex isothermal compression mechanisms. The orbital scroll design provides continuous sealing and dynamic volume change, eliminating the need for bulky isothermal compression equipment while maintaining high thermodynamic efficiency.
4Loss of energy
If conventional engines are designed for specific fuel types, then combustion efficiency is optimized, but fuel flexibility is limited
Solution Approach 1:
The patent designs the external heat source and working fluid system to be universally applicable to multiple fuel types. The separate combustion chamber can burn various fuels (gasoline, diesel, propane, kerosene) without modifying the core engine structure, while the closed-loop CO2 system provides consistent thermal efficiency across different fuel sources.
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 engine achieves high efficiency and power density by using an external heat source to drive a scroll expander, allowing operation in various thermodynamic modes, reducing weight and size while minimizing environmental impact, and enabling flexible fuel use.
Implementation Method 1
Heat supplied to the working fluid is provided external to the engine and is transferred to the working fluid through means of a heat exchanger
Implementation Method 2
means to expand said fluid by use of at least one scroll expander to do useful work
Implementation Method 3
Additional efficiency is captured using means to regeneratively transfer a portion of the working fluid's heat to the pressurized fluid as one means to cool said fluid
Implementation Method 4
means to raise the pressure of said working fluid from a low cycle pressure to a high cycle pressure
Data Source
AI summary
Apparatuses and methods related to an engine for converting heat into mechanical output using a working fluid in a closed circulating system are disclosed. In some embodiments, the engine includes a pump to pressurize the working fluid, a regenerative heat exchanger to transfer heat from a first portion of the working fluid to a second portion, a heating device to heat the working fluid, and a scroll expander to expand the working fluid and generate the mechanical output. Other embodiments may be described and claimed.