The minimum refuelling time of compressed gas cylinders and the metering of the dispensed fuel are important factors for the commercialization of hydrogen-powered vehicles.

The temperature field within a compressed gas cylinder is investigated using modeling and experimental techniques.

A simplified 2-dimensional axisymmetric model is developed for predicting the gas temperature and pressure rise in a hydrogen cylinder during the fill process. The model is then validated by comparison with in-situ measurements of the average temperature rise and temperature distribution inside a working compressed hydrogen cylinder during the process of filling. The model is able to predict the average temperature rise within the cylinder to within 4K. Both experimental and model results show a large conical temperature gradient extending out from the cylinder inlet.

The effects of the initial mass and the total fill time on the temperature rise and the temperature distribution within a compressed hydrogen cylinder during refuelling have been measured.

A type 3, 74 L hydrogen cylinder was instrumented internally with 63 thermocouples distributed along the vertical plane. The experimental fills were performed from initial pressures of 50, 75, 100, 150, and 200 bar at fill rates corresponding to nominal fill times of 1, 3, and 6 minutes. The experimental conditions with larger ratios of final to initial mass produced larger temperature changes. However, the lower ratios generated the largest rates of temperature rise. Longer fill times produced lower final average gas temperatures (compared to shorter fills), and a temperature field with significant vertical stratification due to buoyancy forces at lower gas inlet velocities.

The modeling and experimental results show that a sensor located along the centreline at the non fill end of the cylinder would best represent the average gas temperature within the cylinder.