The dynamic of boiling flows can be considered as a
complex problem where generally more than one instability
mechanism is present. This problem of two-phase flow
instabilities is found in a big variety of energy and chemical
engineering systems such as the channels of Boiling Water
Reactors (BWR), conventional steam boilers, and phase change
heat exchangers used in the chemical industry. Among the
different instability types, one of the most important for the
nuclear engineering field is the in-phase instability that appears
in boiling water reactors (BWR). In this instability type a
synchronized oscillation of the power and the thermal-hydraulic
variables is produced in all the channels of the reactor. This
paper study the influence of the spacer location and the direct
heating i.e. the heating of the boiling channels by neutron and
gamma rays on the in-phase instabilities BWRs.
Papers presented to the 12th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Costa de Sol, Spain on 11-13 July 2016.