DOI: 10.1615/ICHMT.1997.IntSymLiqTwoPhaseFlowTranspPhen
ISBN Print: 1-56700-162-9
ON THE WAVE CHARACTER OF DEVELOPMENT OF BUBBLE BOILING IN CHANNEL FLOW
ABSTRACT
The paper describes results of experimental investigations into the development of bubble boiling in a tubular channel. The investigations extend on the early stage of boiling in a single-phase medium where first bubbles of vapour appear, as well as on the stage of two-phase flow where boiling in the flow core is replaced by surface boiling. For some favourable conditions, the so-called boiling front forms near the exit from the channel, that is at a location of the maximum liquid superheat. The boiling front propagates then upstream with a velocity vp that depends on a number of parameters, including void fraction ε, pressure drop Δр, and heat flux density q at the channel wall. The presented results of measurements exhibit the wave character of development of bubble boiling in channel flow. The experimental investigations are carried out with the help of a computer-aided measuring apparatus operating with a system detectors and electronic transducers of physical quantities describing the process of boiling. A new environment-friendly refrigerants R134a and R123 are used in the course of investigations.