Performance improvement of heat transfer and drag reduction through pristine polymer gum arabic and gum karaya and their hybrid in circular pipe flow
摘要
This investigation was conducted to observe the drag reduction and heat transfer induced through pristine polymer additives gum arabic and gum karaya (GA & GK) and the new copolymer additives (GA + GK) with distilled water as a base fluid in a closed cylindrical pipe loop under a constant heat flux boundary condition. The experimental results of the thermophysical characteristics exhibit that the pristine polymer additives (GA & GK) and new copolymer additives (GA + GK) solutions enhanced the variations of thermal conductivity, density and viscosity values, hence making them a suitable choice for enhanced energy transportation liquid. Under uniform heat flux conditions, the new copolymer additives (GA + GK) with base fluid at all four concentrations exhibit positive performance, which appear better than the pristine polymers in heat transfer coefficient at the flow velocity range from 0.8 to 3.6 ms−1. The overall average and local heat transfer coefficient of the new copolymer additives (GA + GK) at all the ratios improved heat transfer, and it showed greater than that of the pristine polymer additives (GA & GK). The highest heat transfer coefficient was noticed around 21.24 kWm−2 K−1 for GA25:GK75 copolymer additives at the 250 ppm concentration, 30 °C and a flow velocity of 3.6 ms−1, which increased by 62.21% in comparison with the base fluid. However, both the pristine polymer additives (GA & GK) and the new copolymer additives (GA + GK) with base fluid at all four concentrations exhibit drag reduction enhancement at low consistency and slight increase with flow velocity from 0.8 to 3.6 ms−1.