Surface Amendment Study of Porous Channeled Surfaces: An Application of Pool Boiling Amelioration

By submerging the heating surface in a huge deal of stagnant liquid, pool boiling process occurs. Surface coating is a common method to obtain an improved boiling heat transfer. In the present experiment, using spin-coating technique and wire electrical discharge machining (WEDM) simultaneously, the amelioration of heat transfer in nucleate pool boiling was obtained considering distilled water as working fluid at atmospheric pressure. In this regard, on channeled surfaces, titanium oxide (TiO۲) nanoparticles were coated with different concentrations (۱% wt. to ۳% wt.). Moreover, the surface morphology and phase structure were achieved in the prepared materials using the images of Field Emission Scanning Electron Microscopy (FE-SEM). According to the experiment results, heat flux enhances by increasing wall superheat temperature. Furthermore, considerable improvements were achieved in surface porosity through surface coating. Besides, coating the surface and creating channels intensified higher nucleation sites densities consequently improving the boiling performance. Additionally, maximum heat flux (MHF) of ۱۵۱.۹۸ W/cm۲ was obtained by the coated channeled sample at concentration of ۳% wt. with channel's pitch of ۲.۵ mm, ۱.۵ mm width, and ۱.۸ mm depth reached along with the maximum heat transfer coefficient (HTC) of ۹.۴۸ W/cm۲ K. Thereby, the enhancement of ۱۰۵.۳۷ % and ۱۱۰.۶۶ % was obtained compared to the plain surface, respectively.

Keywords:

Pool Boiling , WEDM , Coating , HTC