Phase-Change Heat Storage Backfill: Experimental Study On Rheological Properties Of Backfill Slurry With Paraffin Added

In phase-change heat storage backfill, pipeline transportation of slurry is one of the critical stages, using paraffin microcapsules as phase change material, the influence of paraffin percentage, slurry concentration and shear rate on rheological parameters was discussed and analyzed based on experimental test. Yield stress increases significantly especially paraffin percentage exceeding 5%, for slurry concentration of 68%, 70% and 72%, the increment of yield stress is 171.2 Pa, 353.3 Pa and 353.4 Pa respectively when paraffin percentage increases from 5% to 10%. Viscosity increases significantly with slurry concentration, the average increment is 0.054 Pa.s when slurry concentration increases from 68% to 72%. Shear stress increases with the increase of shear rate, paraffin percentage and slurry concentration. The average increment of shear stress is 32 Pa when shear rate increases from 50 s(-1) to 70 s(-1), shear stress increases significantly when paraffin percentage increases from 5% to 10%, especially reaching 10%, shear stress is larger, and the increment of shear stress caused by increasing concentration is also larger. So it is very important to control the dosage of heat storage material, adjust slurry proportion and determine pipeline parameters, which directly affect flow characteristics and flow resistance, in order to improving the transportation efficiency of backfill slurry. (C) 2020 Published by Elsevier Ltd.