Pretest in forced circulation molten salt heat transfer loop: Studies with thermia‐B

Abstract

Molten salts have potential application as an efficient heat transfer medium in a primary and secondary heat exchanger in high temperature next-generation nuclear power plant. Thermal hydraulic studies are vital for reliable and cost-effective design of the nuclear power plant. Therefore heat transfer study of molten salts will play a vital role in this area. In this work, an experimental system was designed to study thermal hydraulics of the molten salt system up to 700°C. This work describes the pretest results of the experimental facility for extremely corrosive molten fluoride salts with a simulant thermia-B as the working fluid. In the present work, the details of the system are discussed and thermal-hydraulic data for heat transfer fluid thermia-B has been presented. Experiments were carried out at Reynolds number in the range of 4500 to 40 500 and Prandtl number in the range of 34 to 144.Effect of Reynolds number, melting tank temperature, and heat input to test section on forced convective heat transfer was studied under turbulent conditions. Comparison of the experimental data with different empirical correlations has been presented.Abbreviations: CFD, computational fluid dynamic; ICP-AES, inductively coupled plasma-atomic emission spectroscopy; LES, large eddy simulations; MFR, mass flow rates; NGNP, next-generation nuclear plant; PLC, programmable logic controller; RTD, resistance temperature detectors; SCADA, supervisory control and data acquisition; VFD, variable frequency drive; WTMM, wavelet transform modulus maxima. K E Y W O R D S molten salt heat transfer loop, Nusselt number, Reynolds number, thermic fluid, turbulent flow, wall heat flux 1 | INTRODUCTION Per capita, energy consumption relates directly to the overall development of any nation. As per the recent data (2016) per capita, the energy consumption of the United States is 1377 W, Russia is 854 W, France is 736 W, Australia is 1112 W, China is 510 W, and India is 128 W. Therefore, energy is an essential input for the sustained growth in development. The answer to this high and cost-effective energy requirement in future is nuclear power energy. Nuclear power is the cleanest form of mass-energy generation, producing no greenhouse gases like CO 2 , SO 2 , and ash. Nuclear reactors can produce tremendous heat which can be utilized for the production of electricity with high conversion efficiency. Also, due to depletion in fossil fuels, there will be a great demand for alternative cleaner energy resource such as hydrogen. Hydrogen production processes such as thermochemical water splitting and electrolysis require temperatures above 750°C. This high-temperature heat can be obtained from nuclear reactors. But present operational nuclear reactors have maximum outlet temperatures between 300°C and 650°C. 1 Hence, the hydrogen production plant is considered as a major unit coupled with nextgeneration nuclear reactors which are proposed for cogeneration of electricity and hydrogen. The possible heat transfer medium for next-generation nuclear rea...