Internal Combustion Engine Cycle With Optimized Expansion Ratio
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Solution Overview
Problem
Existing internal combustion engines operate at low efficiency, with over 80% of energy production from fossil fuels being wasted, necessitating improved energy efficiency to reduce dependence on fossil fuels and enhance the use of renewable energy sources.
Innovation Solution
Application of the General Cycle thermodynamic cycle, which encompasses common engine cycles, allows for the optimization of compression and expansion ratios to achieve high efficiency by controlling maximum gas pressure and temperature, using a two-stroke direct-injected piston engine design that adheres to the General Cycle principles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional internal combustion engine cycles (Otto, Diesel, Atkinson) are used, then the engine design is simple and well-understood, but the energy efficiency remains low (below 40%)
Solution Approach 1:
The patent applies parameter changes by modifying the thermodynamic cycle parameters, specifically using a six-step cycle that extends the traditional four or five-step cycles. The key parameter changes include: (1) adding a constant pressure heat removal step (step VI) after constant volume heat removal (step V), (2) optimizing the expansion ratio to exceed the compression ratio, and (3) controlling the timing and distribution of heat addition steps. These parameter changes enable the engine to achieve 60% or greater efficiency by better matching the expansion process to the combustion energy release, thereby extracting more useful work from the same fuel input.
2Loss of energy
If fossil fuels are burned for energy production, then energy needs are met, but energy waste exceeds 80% and fossil fuel dependence increases
Solution Approach 1:
The patent converts the traditionally wasted energy into beneficial output by implementing a thermodynamic cycle that captures and utilizes energy that would otherwise be lost. Specifically: (1) The extended six-step cycle captures residual thermal energy during the exhaust stroke by maintaining controlled pressure and temperature conditions, (2) The optimized expansion ratio ensures that the exhaust gases expand more fully, extracting additional work from the combustion products, and (3) The constant pressure heat removal step efficiently captures thermal energy from the combustion gases. These transformations convert what was previously waste heat and pressure into useful mechanical work, achieving 60% or greater efficiency and reducing energy waste.
3Reliability
If renewable energy sources are used to replace fossil fuels, then fossil fuel dependence decreases, but the transition is slow and cannot meet near-term energy needs
Solution Approach 1:
The patent applies universality by designing an internal combustion engine that can efficiently utilize multiple fuel types, including both traditional fossil fuels and renewable fuels such as biomass, biogas, and synthetic fuels. The engine's universal fuel compatibility is achieved through: (1) a flexible fuel injection system that can adapt to different fuel properties, (2) a thermodynamic cycle design that optimizes combustion for various fuel compositions, and (3) control systems that adjust operating parameters based on fuel type. This multi-functionality allows the engine to maintain 60% or greater efficiency regardless of whether it runs on fossil fuels or renewable fuels, providing a reliable bridge technology that can immediately replace fossil fuels with renewable alternatives without sacrificing efficiency.
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 50-60% brake efficiency or higher, with fuel flexibility and reduced energy loss, making it suitable for combined heat and power applications and renewable fuel use.
Implementation Method 1
I. Starting at point 1, a gas is compressed adiabatically (without heat transfer) from V1 to V2. The compression ratio is RC=V1/V2. The pressure increases from P1 to P2.
Implementation Method 2
II. A first heat (fuel) input Q1 raises pressure from P2 to P3 at constant volume. This P3 is the maximum pressure. No work is done and V3=V2.
Implementation Method 3
III. A second heat input Q2 is added at constant pressure as the piston begins to move outward from V3 to V4. (Fuel began to burn at point 2 and burning is complete at point 4.) The total heat input is QIN=Q1+Q2. The work from point 3 to point 4 is W34.
Implementation Method 4
IV. The gas expands adiabatically from point 4 to point 5. The power stroke ends at point 5. The expansion ratio RE=V5/V2 exceeds the compression ratio by the factor A=V5/V1. A is the Atkinson ratio. The work in this step, from point 4 to point 5, is W45.
Implementation Method 5
V. Heat is removed at constant volume. (V6=V5) Pressure decreases from P5 to P1, the initial pressure. (P6=P1)
Implementation Method 6
VI. The gas is compressed and heat is removed at constant pressure. The volume decreases from V5 to V1, the initial volume, and the temperature returns to the initial temperature, T1. (V6=V5) The work from point 6 to point 1, W61, is negative.
Data Source
AI summary
An internal combustion engine operating generally in accordance with a thermodynamic cycle called the General Cycle, achieving maximum efficiency with limited pressure and temperature, and having an expansion ratio RE, a compression ratio RC and an Atkinson ratio A. The Atkinson ratio is in the range from 1.1 to 1.8, the expansion ratio is in the range from 22 to 50, and the compression ratio is in the range from 20 to 36. Given engine parameters, an optimum efficiency RE-RC pair can be determined. The engine may include a high ratio of stroke length to bore, or may be of an opposed piston construction.