Dual-Phase LPG Fuel Supply System for SIDI Engines
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Solution Overview
Problem
LPG-fueled internal combustion engines face challenges such as temperature drops causing propane to freeze in vaporizers, boil-off leading to wasted product and reduced efficiency, and the complexity of dual-fuel systems with separate tanks and control demands.
Innovation Solution
A dual-phase fuel supply system with sensors and valves that manage liquid-vapor balance, temperature, and pressure, using a gravity-fed LPG tank to an intermediate pressure vessel, activating a liquid pump and bypass valve to optimize fuel delivery and minimize boil-off.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a vaporizer or vaporizer-regulator is used to convert liquid propane to gaseous propane, then fuel delivery to the engine is enabled, but the latent heat of vaporization causes significant temperature drop that freezes the liquid propane and stops fuel flow
Solution Approach 1:
The system divides the fuel supply into two separate phases: a liquid phase supply line that delivers liquid propane to the engine, and a vapor phase supply line that handles gaseous propane. This segmentation prevents the temperature drop in the vaporizer from affecting the liquid fuel reservoir, maintaining fuel flow reliability while enabling vaporization when needed.
Solution Approach 2:
An intermediary heating element or heat exchanger is introduced between the liquid propane supply and the vaporizer. This intermediary component transfers heat to the liquid propane, compensating for the cooling effect of vaporization and preventing the fuel from freezing and stopping flow.
2Quantity of substance
If LPG is stored in pressurized canisters at 50-250 psi, then liquid phase fuel can be stored and transported, but heat transfer from the environment causes boil-off that wastes fuel and reduces efficiency
Solution Approach 1:
The system extracts and removes vapor phase fuel from the pressurized canister through a vapor recovery line, preventing it from accumulating and causing boil-off. The removed vapor is either routed to the engine for combustion or vented safely, eliminating the waste associated with uncontrolled boil-off while maintaining liquid fuel storage capacity.
Solution Approach 2:
The system recovers vapor phase fuel that would otherwise be lost through boil-off by capturing it through a vapor recovery line and routing it to the engine for combustion. This converts the wasted energy into useful fuel, improving overall system efficiency while maintaining the ability to store liquid fuel in pressurized canisters.
3Adaptability or versatility
If separate tanks and control systems are used for dual-fuel operation, then flexibility and environmental benefits are achieved, but system complexity and control demands increase
Solution Approach 1:
The system uses a single pressurized canister that can supply both liquid and vapor phase fuel to the engine through controlled routing. This multi-functional approach allows the same hardware to operate in different modes (liquid-only, vapor-only, or mixed) without requiring separate tanks, thereby reducing system complexity while maintaining dual-fuel versatility and environmental benefits.
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 system improves fuel efficiency, reduces environmental impact, and minimizes boil-off, ensuring consistent fuel supply and reducing operational costs by effectively managing the liquid-vapor balance and temperature in LPG fuel systems.
Implementation Method 1
receive the LPG from the canister through gravity feed (aka liquid draw)
Implementation Method 2
pump at least the liquid phase of the LPG fuel through higher pressure rails for controlled delivery
Implementation Method 3
managing the liquid-vapor balance as well as the temperature and pressure of the fuel
Implementation Method 4
managing the liquid-vapor balance as well as the temperature and pressure of the fuel
Data Source
AI summary
A fuel supply system for propane and other LPG fuels is disclosed for internal combustion engines such as spark-ignited direct-injection (SIDI) engines, with features that help manage both liquid and gaseous phases of the LPG fuel. Preferably adapted for use with replaceable fuel canisters, the ECM-managed system has a hot-soak vapor purge system as well as various sensors and valves to prevent excessive boil-off and to otherwise manage the heat and the related liquid-vapor balance of the fuel supply. Although various control strategies are contemplated in different respects, the system preferably uses an intermediate pressure vessel in which the amount of gravity-fed liquid LPG is monitored using a float sensor or the equivalent, and the system is programmed to intervene through valve controls to vent excessively hot LPG vapors from the pressure vessel directly to the engine's intake manifold as a way of managing the heat and liquid-vapor balance in the pressure vessel, accommodating the vented flow by blending the vented fuel vapors with fuel from liquid rail injectors to still produce the desired overall mass flow rate of the fuel to produce the appropriate power levels from the engine.