New Improved Method for Heat Transfer Calculation Inside Rough Pipes

An improved method for heat transfer calculations inside rough tubes is provided. The model has been obtained from a second assessment developed early by the authors on fluid flow in single-phase inside rough tubes. The proposed correlation has been verified by comparison with a total of 1666 experimental available data of 34 different Newtonian fluids, including air, gases, water and organic liquids. The proposed model covers a validity range for Prandtl number ranging from 0.65 to $4.52×104,$ values of Reynolds number from $2.4×103$ to $8.32×106$⁠, a range of relative roughness ranging from $5×10−2$ to $2×10−6$⁠, and viscosity ratio from 0.0048 to 181.5. The proposed model provides a good correlation for $2.4×103≤Re<104$ and $104≤Re≤8.32×106$⁠, with an average error of 18.3% for 70.4% of the data and 16.6% for 74.8% of the data, respectively. The method presents a satisfactory agreement with the experimental data in each interval evaluated; therefore, the model can be considered accurate enough for practical applications. At the present time, a method with similar characteristics is unknown in the available technical literature.