Boiling Heat Transfer in Microtubes at High Flow Rates

Boiling heat transfer is an important heat removal mechanism for cooling applications in micro scale and finds many applications. Many studies were conducted to shed light on boiling heat transfer in microchannels. They were concentrated on saturation boiling at low mass fluxes (G<1000 kg/m²s). In the current study, the emphasis is on high mass fluxes unlike in the literature. Thus, the current study addresses to the lack of information about boiling heat transfer at high flow rates and aims at presenting necessary experimental data. For this, an experimental study was conducted at high flow rates in microtubes. The microtube sizes were used as 250 micrometers. Deionized water was used as working fluid, and the test section was heated by Joule heating. Mass flux was changed from 1000 kg/m²s to 7500 kg/m²s, and heat transfer coefficients and qualities were deduced from local temperature measurements. The effects of mass velocity and quality on boiling heat transfer coefficient were investigated.