Experimental study of heat transfer and flow resistance of supercritical pressure water in a SCWR sub-channel

• Wall temperature difference in the sub-channel is obtained.
• Effects of system parameters on heat transfer are investigated.
• Supercritical heat transfer correlations are assessed against the test data.
• Heat transfer differences in modeled and real sub-channels are studied.

Heat transfer experiments of supercritical pressure water in a sub-channel of SCWR fuel bundle have been performed at Xi’an Jiaotong University. Experimental parameters covered the pressures of 23–28 MPa, mass fluxes of 700–1300 kg/(m2 s) and heat fluxes on the inner wall surface of 200–1000 kW/m2. Experimental results showed that the system parameters of heat flux, pressure and mass flux have great effects on heat transfer, most of these effects are associated with the strong variations of thermophysical properties of supercritical water. Five heat transfer correlations have been assessed with the current set of database, it was found that the correlations of Mokry gives the best predictions of Nusselt number for the flow channel. Based on the form of Mokry correlation, a new empirical heat transfer correlation was developed to improve the predicted accuracy. In the present paper, the wall temperature and heat transfer coefficient of the test section were compared with those of a 2 × 2 central sub-channel. It was found that the heat transfer performance of the present flow channel is worse than that of the real central sub-channel. The flow resistance of supercritical water is reflected in the form of pressure drop, which was discussed with the bulk-flow enthalpy and mass flux.

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