抄録
This study aims to examine the boiling heat transfer and CHF caused by exponentially increasing heat inputs, Q = Q_0 exp(t/τ), to a horizontal vertically-oriented platinum ribbon in a pool of water at atmospheric and saturated condition on the effect of pre- pressurization. Q_0, t and τ are initial heat generation rate, time and period, respectively. The two conditions of pre-pressure such as without and with pre-pressure up to 4.4 MPa are carried out before each experimental run. The exponential period was varied from 10 ms to 20 s. The boiling initiation and CHF occur due to heterogeneous spontaneous nucleation (HSN) by pre-pressurization. The HSN depends on surface condition. In this study, the platinum ribbon has the conditions of the surface roughness, Ra of 0.22 ± 0.02 μm and contact angle, θ, of 51.5 ± 0.7°, respectively. The measured results such as heat transfer process, boiling initiation and CHF were analyzed and compared with previous correlation on the relationship of surface condition.
