EXPERIMENTAL-STUDY AND MODELING OF THE INTERMEDIATE SECTION OF THE NONISOTHERMAL CONSTRAINED VAPOR BUBBLE

The generic nonisothermal constrained vapor bubble (CVB) is a miniatur e, closed heat transfer device capable of high thermal conductance tha t uses interfacial forces to recirculate the condensate on the solid s urface constraining the vapor bubble. Herein, for the specific case of a large length-to-width ratio it is equivalent to a wickless hear pip e. Experiments were conducted at various hear loads on a pentane/quart z CVB to measure the fundamental governing parameter fields: temperatu re, pressure, and liquid film curvature. An ''intermediate'' section w ith a large effective axial thermal conductivity was identified wherei n the temperature remains nearly constant. A one-dimensional steady-st ate model of this intermediate section was developed and solved numeri cally to yield pressure, velocity, and liquid film curvature profiles. The experimentally obtained curvature profiles agree very well with t hose predicted by the Young-Laplace model. The operating temperature o f the CVB was found to be a function of the operating pressure and not a function of the heat load. Due to experimental design limitations, the fundamental operating limits of the CVB were not reached.