Numerical analysis of the convective coefficient on cooling water pipe embedded in concrete

A finite element method was developed to simulate the convective coefficient of cooling water pipe in concrete, and the mean Nusselt numbers on each section in the cooling water pipe were obtained. Numerical results show that the flow field distribution was very complex with a secondary flow appeared in the bend position. The cooling water flow velocity decreased along the pipeline accompanying the secondary flow, it was not advantageous for promoting heat transfer. Nusselt number changed greatly at the joint of straight part with bend section, which decreased gradually along the pipeline with the maximum value change rate of 20%, leading to the decrease of heat transfer between the cooling water and the concrete. It suggested that the Nusselt convective coefficient should be piecewise loaded to ensure the accuracy of results, when employ an approximate method to calculate the temperature field.