Heat transfer enhancement mechanism of pool boiling with self-rewetting fluid

Abstract

Self-rewetting fluid (SRWF) is believed to be a promising and useful working liquid for the application of boiling to the development of high efficient cooling devices with micro structure. To clarify the fundamental heat transfer characteristic and heat transfer enhancement mechanism of pool boiling with SRWF, by employing dilute heptanol aqueous solution as SRWF, a series of boiling experiments have been carried out. In pool boiling tests, a boiling system using a horizontal heated wire was employed. The experimental results show that, the critical heat flux (CHF) of the SRWF increased up to 2.52 times the CHF of water, and the heat transfer enhancement mechanism was discussed. With a high speed video camera, the nucleation boiling process on the heated wire has been recorded. It is found out that, the bubble size of the SRWF is much smaller than that of pure water, and the bubbles of SRWF were hard to coalesce, which is beneficial for the application in small thermal devices. Furthermore, when the heat flux was up to a certain value, the micro-bubble emission boiling (MEB) appeared in the SRWF. It can be concluded that the Marangoni convection induced by surface tension gradient of SRWF is probably one of the key factors causing the formation of MEB.