Boiling heat transfer on a simulated nuclear fuel rod with annular fins

This work describes an improved design for a nuclear fuel rod, which was developed using an experimental circuit that simulates the nuclear rod environment in a pressurized water reactor (PWR). The heat exchanger circuit runs atmospheric to high-pressure boiling water through an annular finned tube (153 fins), which is used to enhance confined heat transfer rates and guide the nucleate boiling process. Volumetric electrical generation (Joule effect) is used to simulate nuclear heating. As much as 48 kW of electrical power is dissipated at different pressure levels up to 40 bar. Under these experimental conditions, heat transfer coefficients of the order of 73,000 W m−2 K−1 are achieved. Our experimental results show that critical safety levels can be easily reached using this design approach. Several nucleate boiling correlations were compared with the controlled experimental data sets, and a modified functional form for the boiling heat transfer coefficient is proposed.