5. Low-pressure boiling

The study of boiling under very low pressure was initially motivated in the 1970s by the development of compact evaporators for sorption refrigeration systems or heat pumps, whether absorption (water-LiBr) or adsorption (zeolite-water). In these systems, water evaporates at saturation conditions close to its triple point (T _pt = 0.01°C; p _pt = 611 Pa). This motivation has been renewed over the last decade under the effect of environmental constraints on synthetic refrigerants. Beyond these applications, low-pressure boiling has become a scientific topic in its own right, to validate the generality of knowledge gained about boiling for more conventional pressure and temperature conditions. Indeed, some of the usual assumptions for boiling at higher pressures are no longer justified near the triple...