Experimental Study On Equivalent Absolute Roughness Of Composite Steel Pipe Stainless Steel Lined

The operation cost of the pump accounts for a large proportion of the operation and maintenance costs of district heating system.Reducing the frictional resistance can reduce the energy consumption of the pump so that the operation cost of the district heating system can be saved.Composite steel pipe stainless steel lined compared with the welded steel pipe,it has lower frictional resistance,which can reduce the resistance well.In order to promote the application of composite steel pipe stainless steel lined in district heating system,this paper will measure the equivalent absolute roughness of lining stainless steel pipe and analyze the experimental results.The measurement requirements of equivalent absolute roughness were summarized by the turbulence theory of circular pipeline and the empirical formula of frictional resistance.According the pipeline steady flow method,a set of experimental device was designed and built to measure the equivalent roughness of DN100 and DN150 pipelines.The maximum flow rate of the pipeline can be controlled at 242.7 m~3/h.The equivalent absolute roughness of DN150 pipelines of Q235B straight welded steel pipe and composite steel pipe stainless steel lined,DN100 pipelines of Q235B straight welded steel pipe and composite steel pipe stainless steel lined was measured by this experimental device.The results,relative error and measurement uncertainty were calculated by using the Alitsouri formula,the Colebrook formula and the Lobayev formula on the base of experiment data.The equivalent absolute roughness of welded steel pipes calculated by the Alitsouri formula,the Colebrook formula and the Lobayev formula is 0.11±0.036mm,0.108±0.03mm and 0.139 mm respectively.While,the equivalent absolute roughness of composite steel pipe stainless steel lined calculated by these three formulas is 0.013±0.005mm,0.005±0.003mm and 0.004 mm respectively.The calculation results of Alitsouri formula are stable and the relative error is the smallest so the calculation results are more reliable.The drag reduction rate is used to evaluate the transmission performance of the composite steel pipe stainless steel lined.The drag reduction rate of composite steel pipe stainless steel lined is between29.2%and 56.2%when the water temperature is 50??110? in comparison of the design value of which of the welded pipe.The drag reduction rate of stainless steel pipe lining is between 5.3%and 36%in comparison of the experimental values of the welded pipe,0.110mm.