Advanced Fueling Method to Achieve Full Fill for Natural Gas Vehicles
Advanced fueling method to achieve safe and consistent full fills for CNG vehicles
The advanced fueling algorithm combined with wireless communication of data between the vehicle and dispenser demonstrated termination of all fills at nearly 100 percent full in every thermodynamically possible case. Further development should be focused around packaging the algorithm with wireless data transmitting hardware in dispensers and vehicles. Pre-cooling is necessary to achieve full fills in cases with high ambient temperature. GTI investigated a variety of potential hardware options, but additional research is needed to develop low cost pre-cooling for CNG stations. The final project report was accepted in February 2019. GTI is using results from this project to work with CSA Group, a leading codes and standards organization for NGVs, to write a guidance document on developing new standards for safe full fills and fueling algorithms.[br /]
Gas Technology Institute (GTI) developed a gas characterization technique and fueling algorithm that uses communication between NGVs and CNG dispensers to identify tank volume, pressure, and temperature prior to filling. The algorithm improves consistency and safety of natural gas vehicle fueling by validating when the vehicle is near the full fill target. GTI also performed fueling simulations to evaluate current state-of-the-art fueling methods and improved fueling algorithms developed using the characterization technique. Using an environmental test chamber and a commercial heavy-duty CNG storage system, GTI tested the improved fueling algorithm and validated its benefits under a variety of real world conditions. GTI also investigated pre-cooling strategies that would be needed to achieve full fills at higher ambient temperatures. Addressing these issues and developing a solution that can be deployed across the NGV industry can improve the competitiveness of low emission, heavy-duty NGVs.
Heavy-duty natural gas vehicles with a 20 percent under fill can result in a 30 gasoline gallon equivalent of underutilized fuel capacity, which directly translates to reduced maximum range. Consistent full fills will effectively increase the maximum range of natural gas vehicles and improve their competitiveness to diesel vehicles.
Achieving consistent full fills improves the economics of natural gas vehicle fleet operations by maximizing vehicle range and reducing frequency of refueling. CNG on-board storage systems are typically oversized to compensate for under filling. The capital costs for on-board storage systems can be reduced by 10 percent ($5,000 per vehicle for some heavy-duty vehicles) if oversizing can be avoided without losing range.
Real world testing of the fueling algorithm demonstrated termination of all fills at nearly 100 percent full, with only one case of slight overfill within the error of the pressure transmitter. Standardizing this fueling algorithm for the CNG industry can result in safer fills and a foundation for future pre-cooling technologies to assist in achieving full fills at high ambient temperatures.
Key Project Members
Agility Fuel Solutions