Film boiling heat transfer from a horizontal non-isothermal surface is formulated with due consideration
to thermocapillary and thermal expansion where thermocapillary convection has been largely ignored in
film boiling. The study is particularity important in nuclear reactor technology where non-isothermal
heater is practically the general situation due to unavoidable non-axisymmetric neutronic flux in the fuel
geometries (cylindrical geometries). Utilizing a simplified geometrical model, an analytical expression
was derived. The above equation applied in a sigmoidal temperature profile results in a central stratification
for film boiling along the heater’s length.