Document Type : Research Paper
Abstract
The problem of frictional pressure drop in crude oil pipelines leads to significant energy losses and increased pumping cost during transportation. Drag reducing agents (DRAs) offer a proven solution to mitigate these losses. This study experimentally investigates the drag reduction performance of bio-derived cashew nut shell liquid (CNSL) and commercial polyacrylamide (PAM) as DRAs in crude oil flow through horizontal pipes of three diameter (0.0127, 0.0254, and 0.0381 m). Pressure drop measurements were conducted in a closed loop system under controlled flow conditions, with CNSL concentrations of10-60ppm. Drag reduction percentage (DR%) was calculated under constant flow rate, using additive-free crude oil as baseline. Results showed non-uniform performance across Reynolds number regimes: CNSL achieved a maximum DR% of 92.3% at 10 ppm in the transitional-turbulent regime (Re ≈ 2622), approaching or exceeding Virk's asymptote (~84%), while PAM reached 89.9% at the same concentration. At higher Re (≈7312), low-concentration CNSL caused drag augmentation (~91.3%), recovering to 62.6–67.8% at 35–60 ppm; PAM maintained stable positive DR% (51.3%). Peak efficiency occurred at the intermediate diameter (0.0254 m), attributed to optimal turbulence intensity for additive turbulence interaction and eddy suppression via phenolic structure. These findings indicate that CNSL a biodegradable phenolic-rich bio-additive (CNSL) can deliver drag reduction levels approaching near-theoretical maximum in crude oil pipelines at concentrations far below those required for conventional synthetic polymers.
