10.1 Introduction
10.2 Surface Wettability Change by Irradiation
10.2.1 Sample and Irradiation Facility
10.2.1.1 Ultraviolet
10.2.1.2 Gamma Rays (γ-Rays)
10.2.1.3 Proton Beam
10.2.2 Contact Angle Measurement
10.2.3 Effect of Irradiations on Surface Wettability
10.3 Effect of Boiling Heat Transfer on Surface Wettability
10.3.1 Experimental Setup and Procedure
Irradiation source | Ultraviolet | γ-ray |
Surface material | TiO2
| Copper oxide |
Irradiation condition | 3 mW/cm2, 30 min | 220 kGy |
10.3.2 Results and Discussion
Subcooling (K) | Before irradiation (°) | After irradiation (°) |
---|---|---|
20 | 62.6 | 31.0 |
40 | 61.5 | 35.7 |
60 | 72.3 | 12.6 |
10.4 Conclusions
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Wettability enhancement was observed by proton-beam irradiation as well as the ultraviolet and γ-ray irradiation.
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In comparing the irradiation between that in air and and that in water, no influence of the radiation environment is observed for ultraviolet irradiation. However, the wettability was well enhanced by γ-ray and proton-beam irradiation in water rather than in air.
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The boiling curve with ultraviolet irradiation moves to the higher wall superheated side in the nucleate boiling region. In contrast, the boiling curve with irradiation moves to the lower wall superheated side in the MEB region.
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A similar tendency of the boiling curve was observed with γ-ray irradiation in comparison to the ultraviolet irradiation.
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The effect of irradiation on the CHF was not obvious at present experimental conditions.