Multifuel Closed-Loop Piston Engine Water Injection Control
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Solution Overview
Problem
Conventional motor vehicle engines suffer from low thermal efficiency and low fuel economy, leading to significant energy wastage and reliance on non-renewable fuels.
Innovation Solution
A multifuel closed-loop thermal cycle piston engine system that employs an externally-fired continuous combustion engine with water injection post-combustion to maintain exhaust gas temperature at a set point, forming a closed-loop thermal cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional internal combustion engines are used, then the vehicle can operate with simple fuel storage and delivery systems, but thermal efficiency is low and fuel economy is poor
Solution Approach 1:
The engine is divided into separate functional stages: compression stage, combustion stage, and expansion stage. This segmentation allows each stage to be optimized independently, with the combustion stage operating continuously at high temperature for maximum efficiency while the expansion stage extracts work, thereby resolving the contradiction between thermal efficiency and system complexity.
Solution Approach 2:
The engine employs continuous combustion rather than intermittent batch firing. Fuel is continuously supplied and burned in the combustion stage, maintaining steady high-temperature conditions that maximize thermal efficiency. This continuous operation eliminates the inefficiencies of repeated ignition and extinction cycles in conventional engines.
2Use of energy by moving object
If hybrid electric vehicles are used, then fuel economy is improved, but greenhouse gas emissions are displaced to power plants and production/maintenance costs increase
Solution Approach 1:
The engine system is designed to accept multiple fuel types (natural gas, hydrogen, biogas, propane, gasoline, diesel) through a universal fuel delivery system. This multi-functionality allows the same engine architecture to achieve high fuel economy across different fuel sources without requiring hybrid electric components, thereby improving fuel economy while avoiding the complexity and cost of hybrid systems.
3Adaptability or versatility
If bi-fuel vehicles with ethanol-gasoline blends are used, then fuel flexibility is improved, but engine performance is substantially reduced
Solution Approach 1:
The engine controls the equivalence ratio and combustion parameters dynamically to optimize performance for each fuel type. By adjusting combustion chamber pressure, temperature, and residence time, the engine maintains high power output across different fuels including natural gas, hydrogen, and biogas, thereby achieving fuel flexibility without sacrificing engine performance.
4Device complexity
If conventional piston engines with intermittent combustion are used, then the engine structure is simple, but approximately 250,000 BTU of heat energy is wasted to the environment
Solution Approach 1:
The engine converts the previously wasted high-temperature exhaust heat into useful work. The continuous combustion process generates sustained high-temperature gases that expand through the expansion stage, converting thermal energy into mechanical work. This transforms the harmful waste heat into a beneficial energy source, dramatically reducing energy loss while maintaining relatively simple engine structure.
Solution Approach 2:
The engine utilizes phase transitions of water injected into the combustion chamber. Water evaporates and converts to steam, absorbing heat and then expanding to drive the pistons. This phase change process efficiently converts thermal energy into mechanical work, reducing heat waste to the environment while maintaining simple engine architecture.
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 solution achieves a significant increase in fuel efficiency, potentially up to 250%, and allows the engine to run interchangeably on various combustible fuels, reducing oil dependence, costs, and carbon emissions.
Implementation Method 1
injecting water into the externally-fired continuous combustion chamber post-combustion... maintain an engine exhaust exiting to the engine exhaust manifold at or below a temperature set point
Implementation Method 2
a compression stage distinct from the drive stage, the compression stage including at least one compression cylinder
Implementation Method 3
an externally-fired continuous combustion chamber configured to conduct continuous combustion of a fuel
Implementation Method 4
a drive stage coupled to an engine exhaust manifold and including at least one drive cylinder... gas pressure drives the at least one drive cylinder
Data Source
AI summary
A multifuel closed-loop thermal cycle piston engine, system and method. A motor vehicle system includes an externally-fired continuous combustion piston-driven engine including a drive stage, a compression stage including a pressure-operated exhaust valve, a combustion stage, a water-injection stage between an outlet of the combustion stage and an inlet of the drive stage, and a programmable electronic control unit programmed to control an exhaust gas temperature including instructions that obtain a temperature of the exhaust gas, and turn on the post-combustion water injectors when the temperature exceeds a pre-programmed set point. A method of operating a closed-loop thermal cycle piston engine includes burning fuel in a combustion stage, measuring a temperature of exhaust gas; and controlling the temperature of the exhaust gas by injecting water into a water-injection stage between an outlet of the combustion stage and an inlet of the drive stage.