Abstract:

This paper describes an experimental investigation on flow boiling heat transfer and visualization of water in a steel micro-groove horizontally laid with rectangular cross section of 0.4×0.4mm².The mass flux G is ranged from 62.5 to 187.5kg/m²s and the inlet temperature T_in is set as 30,45 and 60°C. The results show that, under the condition of low vapor quality, heat transfer coefficient increases with the increase of vapor quality; and hold a certain value until the boiling crisis happes under high vapor quality. The augment of the mass flux could increase the heat transfer coefficient markedly, while the change of the inlet temperature has a weak influence on it. During the visual study, the emergence of great deal of bubbles is observed when the wall superheat is low. The main flow patterns found in the experiment are plug flow and annular flow.

Key words: rectangular micro-groove, flow boiling heat transfer, visualization, flow pattern