Studies of Transition Boiling Heat Transfer With Saturated Water at 1-4 Bar

摘要

Steady-State and transient transition boiling heat transfer tests with water at low pressures have been conducted using a loop in which the test sections were heated by hot mercury. These tests were coupled with phenomenological studies. By using the new and more reproducible steady-state heat transfer data, together with previous data from this program and the literature, a revised heat transfer correlation was developed. The new correlation, which includes a flow effect not previously considered, provides an appreciably better fit of all the data.nTransient heat transfer data in the transition boiling region were obtained in two separate test sections. In both experiments the transient was initiated by a sudden increase of the water flow rate. Comparison of these heat transfer data with the prediction of the new steady-state correlation indicates that the new heat transfer correlation also applies to transient data. The rewetting rates observed were highly dependent on the local void fraction and geometry of the test section. At high void fractions in the annular test section, the rewetting rate was determined by the availability of cooling water to the heated surface.