Experimental study on the effect of step-changing heating on water flow boing in a horizontal long mini-channel

In this study, experiments were performed to investigate the flow boiling of deionized water in a rectangle (1 mm × 2 mm) horizontal long mini channel, and visualization experiments were carried out to study the transformations of flow patterns. Uniform heating (UH for short) and step-changing heating (SCH for short) were studied. The local heat transfer coefficients during both heating methods were compared and analyzed. Heat transfer coefficient curves showed same trends, but the slope of local heat transfer coefficient under of SCH was steeper and the occurrence of the dry-out flow would make the local heat transfer coefficient decrease. Besides, six kinds of flow patterns were observed, and an amendment correlation was proposed for a better prediction of heat transfer coefficient.