Analysis of boiling phenomena associated with liquid jet impingement heat transfer

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Many engineering systems and manufacturing processes require accurate temperature control during operation, examples of which are nuclear safety systems, i.e., emergency core cooling systems in nuclear reactors, electronic packaging cooling systems, and various applications in material processing such as: hot rolling of steel strips, continuous casting, hardening of steel bars, and extrusions and forgings. In many of these applications cooling using liquid jet impingement (LJI) is employed. As liquid jets impinge on the hot surface, heat transfers to the cooling liquid. Thereby, liquid temperature increases up to the boiling point at which time liquid starts to boil. Findings of recent research by the applicant and others demonstrated that the boiling phenomena associated with LJI cooling are very complicated, depend on the interaction of many variables, and have not been completely understood yet. This research has also indicated that the use of LJI cooling has many advantages over other cooling techniques. Those advantages are: (1) its significant flexibility in achieving desired cooling rates, (2) The possibility of using plain water, replacing other cooling liquids, such as, oils and polymer solutions, which are (i) more expensive, (ii) not widely available as water, and (iii) have significantly higher impact on the environment. Because of our lack of full understanding of the complicated boiling phenomena associated with LJI cooling and the significant advantages it can offer, the proposed research has two main streams. The first stream focuses on discovering and understanding the effect of many parameters that have not been fully investigated yet, such as, surface curvature, surface roughness, and interaction of multiple jets on the physics of the complicated boiling phenomena associated with LJI cooling. The goal of this stream is to advance our state of knowledge of LJI cooling. The second stream is concerned with the development of mechanistic models. The main objective of this stream is to present knowledge produced by the first stream in the most useful form for our Canadian industry to develop design guidelines and to achieve optimum operating conditions.