An experiment study of pressure drop and flow distribution in subchannels of a 37-pin wire-wrapped rod bundle

The experiments of pressure drop and flow distribution in subchannels of a 37-pin wire-wrapped rod bundle have been performed to evaluate the reliability of existing friction factor correlations and provide available experimental data to validate the accuracy of the thermal hydraulic codes for the design of the lead-based reactor. The isokinetic sampling technique was applied to measure the flow rate of each subchannel at the rod bundle outlet. The experiments were carried out within the flow rate range of 0.6–5.0 kg/s and the inlet temperature range of 20–80 °C. The Reynolds number of these experiments covers the range of 1100–22,000. The CFD pre-analysis revealed that the number of rods has little effect on the subchannel friction factor. The pressure drop measuring section belongs to the fully developed region. The friction factors and flow split factors measured were compared with the existing friction factor correlations. The prediction results of the Chiu-Rohsenow-Todreas (CRT) model agree well with the experimental results of subchannels. The upgraded detailed Cheng and Todreas (UCTD) model is the best fit wire-wrapped rod bundle friction factor correlation and the maximum error is 15% between Reynolds numbers 1100 and 22,000. When it comes to the interior subchannel, the experimental data falls within 50% of the UCRD model between interior subchannel Reynolds numbers 900 and 13,000. The updated correlations for predicting bundle transition Reynolds numbers are presented in this paper. The subchannel friction factor and the flow split factor are coupled with each other. The derivation of the subchannel transition points proves that the pressure drop experiment and the flow distribution experiment are self-consistent.