Experimental research on drag-reducing effect of drag-reducing coating in heating pipeline

After adding drag-reducing coating to the inner wall of the steel pipe with DN150 pipe diameter, conducts the pressure drop test under five working conditions with flow rate of 65 t/h and water temperature of 20, 25, 30, 35, 40 ℃, obtains that the mean pressure drop on the 87 m pipe with inner drag-reducing coating is 4.63 kPa, and the mean pressure drop on the 87 m pipe without inner drag-reducing coating is 9.63 kPa. Based on the actual pressure drop calculation, the equivalent absolute roughness of the coated pipe section is about 0.01 mm, which is 1/50 of the equivalent absolute roughness of 0.5 mm specified in CJJ 34-2010 Code for design of urban heating pipe networks. Compared with the theoretical calculation value when the equivalent absolute roughness is 0.5 mm, the drag-reducing rate of the drag-reducing coating under the experimental conditions reaches 42.22%. Taking the long-distance heat supply pipeline with a large diameter of DN1200 as an example, when the flow rate is 10 000 to 16 000 m3/h and the water temperature is 20, 40 ℃, the drag-reducing rate of the coated pipe section is calculated to be 32% to 37%.