Experimental investigation on steam-water two-phase flow boiling heat transfer in a staggered horizontal rod bundle under cross-flow condition

Single-phase convection and steam-water two-phase flow boiling heat transfer experiments in an electrically heated 4 × 16 staggered horizontal rod bundle under cross-flow condition have been carried out for the following range: 45 kg m⁻² s⁻¹ ≤ G ≤ 383 kg m⁻² s⁻¹, 20.0 kW m⁻² ≤ q ≤ 55.0 kW m⁻², 0.02 ≤ x_out ≤ 0.57 and 112 kPa ≤ P_in ≤ 190 kPa. The major effects on local flow boiling heat transfer coefficients in horizontal rod bundles were analyzed. Firstly, the row number has a significant effect on local flow boiling heat transfer coefficients since the vapor bubbles generated from the lower rods impinge on the surface of the upper rods and enhance the turbulence there. Secondly, an increasing heat flux contributes to an increase of the average bundle flow boiling heat transfer coefficient at all mass velocities. Thirdly, the local quality can also slightly enhance the flow boiling heat transfer. Fourthly, the flow boiling heat transfer can be enhanced with an increasing mass velocity under lower heat fluxes. In a general, a Chen-type correlation was developed to predict local flow boiling heat transfer coefficients in horizontal rod bundles with a maximum deviation of ±20%.