Dual CNG Supply Pressure Control for Lower Compressor Losses
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Solution Overview
Problem
Existing systems for pressurizing and supplying compressed natural gas (CNG) to internal combustion engines suffer from parasitic losses and reduced fuel economy due to the use of a compressor that increases power consumption, especially during transient engine conditions, leading to inefficiencies and unused fuel in the vessel.
Innovation Solution
A dual-supply system with a bulk and booster vessel, combined with a controller and pressure regulators, dynamically switches between supplies and compressor usage based on pressure thresholds to maintain optimal fuel pressure for the engine, minimizing compressor operation and optimizing fuel utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If a compressor is used to maintain fuel pressure above threshold by raising storage pressure to desired rail pressure, then the pressure of gaseous fuel is maintained, but parasitic losses increase and fuel economy decreases
Solution Approach 1:
The system divides the fuel supply into two separate vessels: a bulk supply vessel for long-term storage and a booster supply vessel for immediate pressurization. This segmentation allows the compressor to operate only on the booster vessel when needed, rather than continuously pressurizing the entire fuel supply, thereby reducing parasitic losses while maintaining adequate fuel pressure.
Solution Approach 2:
The booster vessel is pre-filled with pressurized gas that can be quickly supplied to the engine without compressor intervention. This preliminary action ensures that during transient conditions requiring rapid pressure response, the system can meet demand from the pre-pressurized booster supply without activating the compressor, thus avoiding energy losses.
2Productivity
If compressor capacity is increased to meet transient engine fuel demand, then fuel demand during transient conditions is satisfied, but parasitic losses become too great for engine operation
Solution Approach 1:
By segmenting the fuel supply into bulk and booster vessels, the system enables a smaller compressor to suffice for the booster vessel only. This segmentation allows the system to meet transient fuel demand through the pre-charged booster supply without requiring a large-capacity compressor that would generate excessive parasitic losses during continuous operation.
Solution Approach 2:
The compressor operates periodically rather than continuously, activating only when the booster vessel pressure drops below a threshold. This periodic operation maintains adequate fuel supply capacity while minimizing parasitic losses by keeping the compressor idle during periods when the pre-pressurized booster supply can meet engine demand.
3Loss of energy
If compressor operation is reduced to decrease parasitic losses, then fuel economy improves, but fuel pressure may drop below threshold
Solution Approach 1:
The booster vessel is pre-charged to a high pressure level before compressor operation is reduced or stopped. This preliminary pressurization creates a pressure buffer that maintains adequate fuel pressure in the system even when the compressor is inactive, preventing pressure drops below the threshold while minimizing parasitic losses during compressor idle periods.
Solution Approach 2:
The booster vessel acts as an intermediary pressure buffer between the bulk supply and the engine fuel rail. It stores pressurized gas that can be quickly delivered to maintain rail pressure without requiring continuous compressor operation, thus mediating between the need for pressure maintenance and the desire to reduce parasitic losses.
4Loss of energy
If dual supply system with bulk and booster vessels is used, then compressor operation is minimized and fuel economy is optimized, but system complexity increases
Solution Approach 1:
The bulk supply vessel serves multiple functions: long-term fuel storage, pressure stabilization, and as a source for repressurizing the booster vessel when needed. This multi-functionality reduces the need for additional dedicated components, thereby limiting the increase in system complexity while achieving the fuel economy benefits of minimized compressor operation.
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 approach reduces parasitic losses and improves fuel economy by efficiently managing fuel pressure without excessive compressor usage, ensuring consistent supply to the engine, even during varying demand conditions.
Implementation Method 1
a compressor that pressurizes the gaseous fuel fluidly received from the first supply or the second supply
Implementation Method 2
a pressure regulator that regulates a pressure of the gaseous fuel fluidly received from the first supply or the second supply
Implementation Method 3
An accumulator can be configured to fluidly receive gaseous fuel from the compressor and the pressure regulator
Data Source
AI summary
An apparatus and method for pressurizing and supplying a gaseous fuel to an engine includes a first supply and a second supply of the gaseous fuel stored as a compressed gas. A pressure regulator regulates a pressure of the gaseous fuel fluidly received from the first supply or the second supply, a compressor pressurizes the gaseous fuel fluidly received from the first supply or the second supply, and an accumulator fluidly receives gaseous fuel from the compressor and the pressure regulator. A supply-select valve apparatus is in fluid communication with the first supply and the second supply and is actuatable to fluidly connect the first supply with the compressor or the pressure regulator, and to fluidly connect the second supply with the compressor or the pressure regulator.