A universal approach to understanding cryogenic quenching in pool boiling

Abstract

This study experimentally and theoretically investigated the effects of material properties and geometric dimensions on quenching process of a flat plate in a liquid nitrogen pool. Quenching experiments were performed using stainless steel, aluminum, and copper plates with thicknesses ranging from 0.3 to 5.0 mm. Experimental results showed that the minimum heat flux (MHF) temperature increased as the plate heat capacity per unit area decreased. A theoretical model was developed to predict the MHF temperature and regime transition time, defined as the time required to reach the MHF point, and agreed well with experimental data, with MAPEs of 7.1% and 14.9%, respectively. The theoretical model identified three parameters governing quenching: (1) lumped capacitance time scale associated with transient heat conduction, (2) excess MHF temperature, and (3) local temperature drop resulting from liquid-solid contact. According to the first parameter, the regime transition time is linearly proportional to the heat capacity. The second one describes the dependence of MHF temperature on heat capacity, with smaller heat capacity leading to higher MHF temperature and shorter regime transition time. The third one accounts for thermal effusivity and diffusivity effects on regime transition, which are negligible when these properties are sufficiently high. Finally, a universal approach to understanding quenching is proposed: the contribution of transient conduction can first be isolated, as evidenced by the collapse of quenching curves onto a single curve independent of material and geometric parameters. This, in turn, enables a systematic analysis of the effects of individual parameters on regime transition.