Rod bundle thermal-hydraulics experiment with water and water-Al₂O₃ nanofluid for small modular reactor

This study offers state-of-the-art rod bundle facility development and testing with modified coolant, with the prospects and challenges for the small modular reactor (SMR). The thermal-hydraulics characteristics of a 3×3 square array rod bundle tested under a fully-developed single-phase turbulent upflow condition using pure water and water-mixed alumina nano-size particles. This rod bundle with specially-designed grid spacers and flow distributors developed to simulate a unit block of SMR core. Test data collected for a wide range of inlet flow conditions (Reynolds numbers from 21,000 to 100,000) with and without heating and nanoparticle mixing in water. Then, the heat transfer performance in the form of Nusselt number, Nu, and pressure drop was calculated and compared with the estimation of well-established models and correlations. The pressure drop test data of water appropriately matched with estimation data. In the heat transfer study, the value of Nu increased with the percentile inclusion of nanofluid. But the addition of nanoparticle is recommended to a limit as it increased the pressure drop value, which is reasonably high for some of the SMRs.