variavel0=<b>Edgard Poiate Junior</b> - poiate@petrobras.com.br PETROBRÁS
<b>José Luiz Gasche</b> - gasche@dem.feis.unesp.br UNESP
<b>Abstract.</b> This work refers to the experimental study of the two-phase flow of a liquid mixture composed by mineral oil (SUNISO 1GS) and refrigerant R12 along two horizontal straight tubes of constant diameter. One tube is used for flow visualization and the other is instrumented for pressure and temperature measurements. The results show a predominant liquid mixture flow at the inlet tube region with small bubbles arising eventually. It is noted a mixture temperature practically constant and a linear reduction in the pressure at this single-phase region. As the mixture flows down through the tube a small number of bubbles arise due to the reduction of the solubility of refrigerant in the oil, which is caused by the pressure drop of the flow. The number of bubbles increases with the continuos pressure drop until that a foam flow region is observed close to the exit of the tube. A great reduction in the pressure and temperature is observed at this two-phase region. Besides, it is also observed a great instability in the flow, which is confirmed by several flow patterns at the same position at different instant and by a large pressure oscillation.
<b>Keywords.</b> Oil-refrigerant mixture, Two-phase flow, Foam, Flow visualization.