Experimental investigation of turbulent heat transfer and fluid flow in internally finned tubes with surface roughness

摘要

An experimental investigation of simultaneously developing, steady, turbulent fow under heating conditions in both straight and helically finned tubes with surface roughness (sand grain type) has been performed. Length-averaged heat transfer and pressure drop were obtained using air as the test fluid in twelve rough fin tubes and one rough tube without fins. Adiabatic friction factors and Nusselt numbers were measured for fin geometries of 18<=N<=60, 0.056<=H<=0.269, 7.562#mu#m<=Ra_(t,i)<=14.941#mu#m and 0 deg<=#gamma#<=26 deg> Turbulent flow operating conditions ranged from 7,500