A comparison of magnetic resonance, X-ray and positron emission particle tracking measurements of a single jet of gas entering a bed of particles

Measurements of the lengths of a single jet of gas entering a packed bed were made using magnetic resonance imaging (MRI), positron emission particle tracking (PEPT) and X-ray radiography and the results compared. The experiments were performed using a Perspex bed (50 mm i.d.) of poppy seeds: air at 298 K was admitted to the base of the bed through a single, central orifice, 2 mm in diameter. Poppy seeds (Geldart Group B, measured minimum fluidisation velocity with air at 298 K and 1 atm of 0.13 m/s and particle density ~1060 kg/m3) were used because of their high content of oil, which contains mobile protons and hence is suitable for MRI examination. The lengths of jet measured using the three techniques were in agreement between 50 m/s