THE RELATIONSHIP OF FORCED CONVECTION QUENCH DATA TO STEADY-STATE NUCLEATE BOILING DATA
An experimental facility has been built to perform fundamental quenching experiments under simple conditions with the aim of providing sufficient transient boiling data for comparison with steady-state data. A thin-walled heater tube (0.365 in ID, 0.5 in OD, 30 in long) of 316 stainless steel material was employed as the test section. It was completely dried out and heated to temperatures beyond the Leidenfrost point before being flooded from the bottom with subcooled water. The following ranges of parameters were investigated: 700−1000°F initial wall temperature, 90−215 psia pressure, 20−172°F inlet fluid subcooling, and 0.7 × 106 − 1.9 × 106 lbm/hr-ft2 mass velocity.
In addition to the transient boiling data, nucleate boiling data at steady-state conditions were also collected on the test section. These data agreed reasonably well with the Jens-Lottes correlation for nucleate flow boiling. However, the nucleate boiling heat flux data generated from the transient tests were considerably shifted to the right of the Jens-Lottes nucleate boiling curve. Consequently, a modified correlation which employs a correlation parameter that is proportional to the rate of change of the wall superheat with respect to time is proposed for transient nucleate boiling. This correlation effects a reduction in the heat transfer coefficient for the transient and is valid only for forced convection quenching in water for the range of parameters tested.