Experimental measurements of gas pressure drop of packed pebble beds

• Published in: Fusion engineering and design 2020-11, Vol.160, p.111836, Article 111836
• Main Authors: Panchal, Maulik, Saraswat, Abhishek, Chaudhuri, Paritosh
• Format: Article
• Language: English
• Subjects: Aluminum oxide; Breeder blanket; Breeder reactors; Diameters; Differential pressure; Gas flow; Gas pressure; Lithium; Lithium meta-titanate; Low pressure gases; Mass flow; Nuclear fuels; Packed beds; Pebble bed; Pressure drop; Stainless steel; Stainless steels; Tritium
• ISSN: 0920-3796; 1873-7196
• DOI: 10.1016/j.fusengdes.2020.111836

•An experimental facility has been developed for gas pressure drop measurements across the pebble beds.•Experiments have been performed using the nitrogen gas on the stainless steel spheres, alumina pebbles and lithium meta-titanate pebbles.•The gas pressure drop increases with a decrease in the diameter of the pebble and inlet gas velocity.•The predicted values of pressure drop by Ergun’s equation agree well with the experimental data.•The obtained values of gas pressure drop will support to benchmark the simulation results in the future. The nearly spherical shaped ceramic pebble beds in the breeder blanket of the future fusion reactor are purged by low-pressure gas to channelize the produced tritium fuel into the tritium extraction system. The required pumping power for the flowing gas in pebble beds can be estimated using the pressure drop across the pebble beds. The aim of this work is to measure the gas pressure drop experimentally across packed pebble beds as a function of pebble sizes, pebble shapes, pebble materials, and gas velocity. The pebble beds are packed in a cylindrical-shaped stainless steel container with an inner diameter of 24 mm and a length of 130 mm. The various experiments have been performed on stainless steel spheres (Diameter: 1 mm, 2 mm, 3 mm, and 4 mm), alumina pebbles (Mean diameter: 1 mm and 1.5 mm), and lithium meta-titanate pebbles (Mean diameter: 1 mm and 1.3 mm). The gas flow has been controlled and measured using a digital mass flow controller. The static differential pressure across the pebble beds has been monitored by a differential pressure transducer. The pressure drop significantly increases with a decrease in the diameter of pebbles/spheres and an increase in the packing fraction of the bed. The material type does not affect the results which are too obvious for the fixed pebble bed which is considered in these experiments. The obtained experimental results of gas pressure drop have been compared and agreed well with the prediction of the Ergun’s correlation.