Compressed Gas Filling Valve Modulation
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Solution Overview
Problem
Existing CNG dispensing systems often fail to completely fill storage vessels due to temperature and pressure variations, leading to underfilling, especially during fast-fill processes, as they terminate dispensing at a cutoff pressure before the vessel is fully charged.
Innovation Solution
A method and system that utilize a controlled valve to modulate the temperature and pressure of the fuel gas, compensating for the heat of compression by dispensing a predetermined amount of cooled gas and then increasing the flow rate to ensure complete filling without exceeding safety pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the dispensing system uses a cutoff pressure to terminate filling, then safety is improved, but the vessel may not be completely filled
Solution Approach 1:
The system continuously monitors the temperature and pressure of gas in the storage vessel during dispensing, using this feedback to dynamically adjust the dispensing process. Temperature and pressure sensors provide real-time data to the control system, which calculates the actual fill level and determines when to terminate dispensing, ensuring both safety and complete filling.
Solution Approach 2:
The system changes the termination criterion from a fixed pressure cutoff to a dynamic assessment based on temperature and pressure parameters. By monitoring how temperature and pressure evolve during dispensing, the system can determine when the vessel is truly full, allowing it to achieve complete filling while maintaining safety margins.
2Productivity
If the dispensing system increases mass flow rate to speed up filling, then productivity is improved, but temperature control becomes difficult
Solution Approach 1:
The system uses temperature sensors to monitor gas temperature during dispensing and feeds this information back to the control system. Based on the temperature feedback, the controller dynamically adjusts the mass flow rate through the valve, allowing high-speed filling while preventing excessive temperature rise that would compromise filling accuracy or safety.
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
Enables the complete filling of CNG storage vessels regardless of ambient temperature or initial pressure, preventing underfilling and ensuring the vessel is filled to its rated capacity without exceeding safety limits.
Implementation Method 1
When the controlled valve is in the first position, the fuel gas has a first temperature upstream of the controlled valve, a second, lower temperature downstream of the controlled valve
Data Source
AI summary
Systems and methods for completely filling a storage vessel with a fuel gas. One method includes flowing the fuel gas along a fluid conduit in fluid communication with the storage vessel and actuating a valve disposed along the fluid conduit to provide a predetermined difference between the pressure of the fuel gas upstream of the valve and the pressure of the fuel gas downstream of the control valve. The predetermined difference is selected such that the temperature of the fuel gas is reduced to a predetermined temperature after passing through the valve. The method further includes dispensing the fuel gas into the storage vessel at a first mass flow rate.