HEAT TRANSFER IN A SODIUM-POTASSIUM HEAT EXCHANGER (POTASSIUM BOILER) MADE OF HELICALLY-COILED TUBES.

Results of an experimental study of heat transfer and its crisis in boiling of potassium in (stainless-steel or niobium-alloy) tubes heated by electricity or by hot sodium are described. The relationships governing the process are analyzed and expressions are derived for the potassium boiling heat transfer rate, critical heat fluxes, transcritical heat transfer rates and convective heat transfer over the hot sodium temperature range of 880 to 1350 degree K. The tube wall temperature along the coil is calculated from the above relationships and is then compared with experimental data.