Systems that store heat in a liquid that can generate vapor for various applications by flash evaporation, sometimes known as steam accumulators, are a relatively simple way for integrated heat storage and vapor/steam generation. Applications include buffering of the transient heat supply and demand in conventionally-fuelled boilers, locomotives and steam power generation systems and more recently in solar thermal power. The information available about this type of heat storage was mostly about steady state operation with little attention to the flash evaporation aspects. In this paper we describe the state of the art and a well-instrumented facility for the experimental study of a variant of such systems, the Heat Storage Flash Boiler that includes a 19.28 m3 storage/flash tank, which was developed by us for experimental examination of its storage and discharge performance for temperatures between 65 °C and 120 °C and pressures from 0.5 to 2 bars (50–200 kPa).. The applicability of such a facility as a generator of steam for feeding a turbine or other purposes has been demonstrated. Flashing has been induced at water temperatures between 80 °C and 100 °C. At 97 °C, the average flow rates obtained ranged between 14 kg/hr for a driving pressure drop of Δpf = 3.2 cm Hg (4.266 kPa), and 390 kg/hr for Δpf = 5.1 cm Hg (6.799 kPa). Specific attention was paid to key issues including the flash evaporation phenomenon, conditions for choked flow of the steam and for mist entrainment, and need and ways for the storage water deaeration. Detailed results for the experimental runs, and the mass flow generation rate of water evaporated was well-correlated to the driving pressure drop for flashing, Δpf. The experiments have provided useful information about the associated heat storage issues and flash steam generation phenomena. Basic considerations and methods for the design of integrated thermal storage/steam generation systems, the Heat Storage Flash Boilers are presented.

This content is only available via PDF.
You do not currently have access to this content.