Heat transfer of a bubbly flow in a vertical rod bundle 3X3

This work aims at creating a reserve for increasing the efficiency of nuclear power plants. One of the main ways to intensify heat transfer in fuel assemblies is to increase the permissible mass concentration of the vapour phase. It is known that the introduction of a gas phase into a fluid flow leads to a modification of the flow structure and can significantly change the key thermal and hydraulic flow parameters, for example, the heat transfer coefficient. In this paper, we present the results of an experimental study of an ascending bubble flow in a vertical rods bundle 3X3. The working liquid was distilled water. The experiment was carried out at Reynolds numbers from 4000 to 11000 and gas flow rate ratios from 3 to 10%. As a result of the experiment, the heat transfer coefficients from the central rod heated by the electric current to the flow have been determined. It is shown that gas bubbles have the greatest effect on heat exchange at low Reynolds numbers and at a maximum distance from the spacer grid.