Heat transfer and critical heat flux of subcooled water flow boiling in a HORIZONTAL circular tube

Experimental investigation on bubble sliding during subcooled flow boiling in microchannel

“…Flow boiling is widely used for cooling of high heat flux devices due to the outstanding heat dissipation performance of phase change phenomenon [1,2] and receives extensive and sustained attention [3,4]. In recent years, with the minimization of electronic element and the development of packaging technology, the ultra-high heat flux generated in mini-/micro-scale devices needs to be removed timely for safe operation.…”

Transient critical heat fluxes of subcooled water flow boiling in a SUS304-circular tube caused by a rapid decrease in velocity from non-boiling regime

“…Figure 3 shows the SEM photograph for the SUS304 test tube of d=6 mm with the rough finished inner surface (RF). The inner surface roughness is measured 3.89 m for Ra, 21.42 m for Rmax and 15.03 m for Rz.…”

Transient Critical Heat Fluxes of Subcooled Water Flow Boiling in a SUS304-Circular Tube Caused by a Rapid Decrease in Velocity From Non-Boiling Regime

“…1) As soon as the inlet flow velocity decreases, the Pin and Pout oscillate violently and the Ts and Tout have started to increase. At the flow transient CHF point, the heater inner surface temperature, Ts, rapidly increases, although the heat flux, qcr,sub, oppositely decreases at the flow transient CHF.2) Most of the flow transient CHF data are within -34.1 to 15.4 % and -39.7 to 0.55 % differences of the values calculated from the steady-state CHF correlations against outlet and inlet subcoolings for the circular test tube, Eqs (21). and(22), respectively.…”

“…In this study, it is firmly confirmed that the steady-state CHF correlations against outlet and inlet subcoolings, Eqs. (21) and 22, can delineate not only the authors' published CHF data (3206 points) for the HORIZONTAL and VERTICAL SUS304 test tubes with the wide ranges of inlet pressures (Pin=159 kPa to 1.1 MPa), inner diameters (d=2 to 12 mm), heated lengths (L=22 to 150 mm) and flow velocities (u=4.0 to 13.3 m/s) [24][25][26][27][28][29][30][31][32] within 15 % difference for 30 KTsub,out140 K and 40 KTsub,in151 K but also the flow transient CHF for the circular tube of 6 mm inner diameter obtained in this work within -34.1 to 15.4 % and -39.7 to 0.55 % differences, respectively. We have supposed that the expressions of flow velocity map (ucr/ucr,st versus ) and critical heat flux one (qcr,sub/q0 versus ) at flow transient CHF against steady-state critical heat flux would be very useful to discuss the mechanism of the transient critical heat flux of subcooled water flow boiling caused by a rapid decrease in velocity, which would occur due to the hydrodynamic instability suggested by Kutateladze [33] and Zuber [34] or due to the heterogeneous spontaneous nucleation at the lower limit of the heterogeneous spontaneous nucleation temperature [35] (29) It is assumed that the transition to film boiling at the deceleration caused by a rapid decrease in velocity, , lower than -5 m/s 2 would occur due to the heterogeneous spontaneous nucleation but not due to the hydro-dynamic instability.…”