Heat transfer in subcooled water boiling in transverse flow around tube bundles

The heat transfer in forced convection flow and subcooled water boiling is studied for a single-row bundle of tubes located in a slit gap between plane walls. The experiments have been performed for the ranges of: pressures 0.1-5 MPa. heat fluxes - 50-500 kW/m2, subcoolings - 4-40 deg C and Reynolds numbers - 5-140x103. The existence of three zones with a developed character of the heat exchange has been established: forced convection, undeveloped and developed boiling. The boundaries between separate zones have been established from changes in the character of the heat transfer coefficient dependence. The wall local temperature changes have shown that there exists a temperature difference over the perimeter of the tube which decreased with the initiation of boiling. The temperature of the upper generator tube is considerably higher owning to, lower heat transfer coefficient and higher liquid temperature. On this part of the tube the boiling began sooner. With a subsequent increase in the heat flux the growth rate of the wall local temperature slowed down and for other constituents conserved at the previous high level. As a result, the temperature values at other generators came closer. With the developed boiling the maldistribution was insignificant, maximum temperature difference not exceeding 16 deg C