CNG Dispenser Control Valve Cooling for Complete Vessel Fill
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Solution Overview
Problem
Existing CNG dispensing systems often fail to completely fill storage vessels due to factors like ambient temperature, initial pressure, and hydraulic losses, leading to underfilling, especially during fast-fill processes.
Innovation Solution
A method and system that utilize a control valve to modulate the temperature of the dispensed gas and compensate for compression heating by creating a pressure differential across the valve, ensuring the gas is cooled before being introduced into the storage vessel, allowing for complete filling regardless of ambient temperature or initial pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the dispensing system uses a fast-fill process to increase filling speed, then the productivity is improved, but the storage vessel cannot be completely filled because the pressure exceeds the cutoff pressure before the vessel reaches its rated capacity
Solution Approach 1:
The system pre-cools the compressed natural gas before it enters the storage vessel using a heat exchanger. This preliminary cooling action reduces the gas temperature and pressure, allowing the vessel to be filled to its rated capacity without exceeding the cutoff pressure, even during fast-fill operations.
Solution Approach 2:
The system changes the temperature parameter of the gas by cooling it before dispensing. By reducing the gas temperature through the heat exchanger, the system lowers the pressure at which the gas enters the storage vessel, enabling complete filling while maintaining fast-fill speeds and staying within the cutoff pressure limit.
2Manufacturing precision
If the system compensates for ambient temperature differences to maintain filling accuracy, then the manufacturing precision is improved, but the system complexity increases due to additional temperature compensation mechanisms
Solution Approach 1:
The system introduces a heat exchanger as an intermediary device between the compressed natural gas source and the storage vessel. This intermediary component actively manages temperature differences, providing reliable temperature compensation without requiring complex control algorithms or multiple sensors, thus maintaining filling accuracy while limiting complexity increase.
3Reliability
If the dispenser terminates filling when the gas reaches the cutoff pressure as a safety measure, then the safety is improved, but the storage vessel remains underfilled and cannot reach its rated capacity
Solution Approach 1:
The system changes the temperature parameter of the gas by cooling it before dispensing. By reducing the gas temperature through the heat exchanger, the system lowers the pressure at which the gas enters the storage vessel, enabling complete filling while maintaining fast-fill speeds and staying within the cutoff pressure limit.
Solution Approach 2:
The system pre-cools the compressed natural gas before it enters the storage vessel using a heat exchanger. This preliminary cooling action reduces the gas temperature and pressure, allowing the vessel to be filled to its rated capacity without exceeding the cutoff pressure, even during fast-fill operations.
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 without exceeding the dispenser's cutoff pressure, ensuring the vessel is filled to its rated capacity without overfilling, even at higher ambient temperatures.
Implementation Method 1
actuating the control valve to provide a predetermined difference between the pressure of the fuel gas upstream of the control valve and the pressure of the fuel gas downstream of the control valve, wherein the predetermined difference is selected such that the temperature of the fuel gas is reduced to a predetermined temperature after passing through the control valve
Data Source
AI summary
A method of filling a storage vessel with a fuel gas at a fuel dispenser. In various embodiments, the method includes providing a fuel dispenser comprising a housing defining a fluid flow path therein, the fluid flow path operatively connected with a source of the fuel gas. The fuel dispenser includes a control valve disposed along the fluid flow path and a controller in operative electronic communication therewith. The method also includes actuating the control valve to provide a predetermined difference between the pressure of the fuel gas upstream of the control 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 control valve. The method also includes dispensing the fuel gas into the storage vessel, the fuel gas having first mass flow rate.