Studying the effective longitudinal turbulent transfer at transverse streamlining of in-line tube bundles

Resumo

The experimental values of the effective thermal conductivity of water at transverse streamlining of the in-line rod bundles with square packing have been obtained. The effective thermal conductivity of water was measured in the direction parallel to the axes of the rods. The measurement method implied mixing of two flat parallel water flows in the working area; the latter moved at the same velocities, but had different temperatures. By measuring the flow temperatures before and after the mixing area, the amount of heat transferred from the hot to the cold flow was determined and the effective thermal conductivity of the liquid was calculated. In the investigated range of Reynolds numbers (from 7·10³ to 8·10⁴), calculated by the velocity in a narrow section, the experimental effective thermal conductivity of water showed a linear increase with increasing velocity and good agreement with the results of calculations by the integral turbulence model. The obtained experimental data have confirmed the possibility of using an integral turbulence model to calculate the parameters of the anisotropic porous solid model, used in CFD codes simulating thermal-hydraulic processes in the active zones of nuclear reactors and heat exchangers.