10.3.1 Experimental Setup and Procedure

A schematic view of the experimental apparatus for pool boiling experiments with small heat transfer area is shown in Fig. 10.5. The apparatus consists of a copper block, a furnace, a rectangular container, and a heat exchanger. The copper block has a cylindrical part (10 mm in diameter, 15 mm in height). Several cartridge

c

Fig. 10.4 Change of contact angle from ultraviolet, y-ray, and proton beam irradiation to TiO2 sample. (a) Ultraviolet irradiation. (b) y-Ray irradiation. (c) Proton beam irradiation heaters are installed in the copper block (3 kW in total). Two different copper blocks were fabricated to investigate the wettability effect on the heat transfer: one is a test section for ultraviolet irradiation and the other is for y-ray irradiation. Both test sections are illustrated in Fig. 10.5: three thermocouples are inserted into the cylindrical part of each copper block to estimate heat flux and surface temperature.

Copper

Distance from the surface [mm]

Thermocouple TC1*»■ TC2:6’29’ TC3* 31 <Cu> Fig. 10.5 Schematic of experimental apparatus

The heat transfer surface for ultraviolet experiments is coated by a TiO2 thin film by a sputtering process in Kyushu University. The surface for y-ray experiments is polished with #400 emery paper and then heated in air at 200 ° C for 1 h. After the thermal oxidation of the copper surface, it is irradiated in the 60Co facility where the integrated dose is 220 kGy. The irradiation conditions for heat-transfer experiments are summarized in Table 10.1.