Transient contact behavior of aqueous polymer solution droplets with hot solid and formation process of polymer enriched-layer

2017 Fiscal Year Final Research Report

• Project/Area Number: 15K05825
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Thermal engineering
• Research Institution: Kyoto University
• Principal Investigator: FUJIMOTO HITOSHI 京都大学, エネルギー科学研究科, 准教授 (40229050)
• Co-Investigator(Kenkyū-buntansha): 宅田 裕彦 京都大学, エネルギー科学研究科, 教授 (20135528)
• Project Period (FY): 2015-04-01 – 2018-03-31
• Keywords: aqueous polymer / boiling heat transfer / flow visualization / spray cooling / droplet dynamics

Outline of Final Research Achievements

In the metal forming industry, quench hardening is commonly used to strengthen steel products by rapidly cooling hot materials with spray jets. One of the typical coolants is an aqueous polymer solution. During the hardening process, several phenomena occur simultaneously, namely, coolant boiling, separation of the polymer from the aqueous solution, and formation of a polymer-enriched layer on the solid surface. We developed experimental methods to observe these phenomena and explored that polymer-enriched layer formed temporarily at substrate temperatures higher than the temperature range for thermal decomposition measured by the thermogravimetric curve. The lifetime of this temporary polymer-enriched layer decreased as the substrate temperature increased. The lifetime was also influenced by the type of solid substrate. In addition, we found that aqueous polymer solution reduced heat transfer between droplets and substrate in some temperature range of solid.

Free Research Field

熱流体工学