# Subcooled Flow Boiling Heat Flux Enhancement Using High Porosity Sintered Fiber
## 4 Conclusions  
The present research reports the flow subcooling heat flux enhancement using high porosity sintered fiber as a passive method in comparison with the bare surface under atmospheric pressure. Mass flux and inlet subcooling parameters were taken as parameters. Experiments were stopped if the heat flux was around 2.5 MW/m\({}^{2}\) to avoid damage to the experimental setup or if the critical heat flux was reached. The influence of the high sintered fiber thickness porosity presents a direct influence in the amount of heat flux, and the wall superheat temperature as well the onset nucleate boiling was shifted to lower wall superheat temperature using low porosity thickness. In general terms, the amount of heat flux was improved using the high sintered fiber at low porosity thickness. However,  
Figure 8: Flow and bubble formation pattern at the maximum heat flux for all the porous thickness: \(\Delta T_{sub}=50\) K; \(G=400\) kg\(\cdot\)m\({}^{-2}\cdot\)s\({}^{-1}\).  
Figure 9: Flow and bubble formation pattern at the maximum heat flux for all the porous thickness: \(\Delta T_{sub}=70\) K; \(G=400\) kg\(\cdot\)m\({}^{-2}\cdot\)s\({}^{-1}\).  
in the case of the porosity of 2 mm the heat transfer performance was reduced, and the wall superheat increased at low subcooling inlet temperature. The porous thickness of 0.5 mm presented the best performance for all the cases followed by the 0.2 mm porous thickness. For the specific case of the 1 mm porous thickness, the wall superheat was reduced in comparison with the bare surface, however, the critical heat flux was reached at high inlet subcooling temperature. In addition, the bubble formation and departure rate was higher at high inlet subcooling temperature, and only for the case of the mass flux of 600 kg\(\cdot\)m\({}^{-2}\)\(\cdot\)s\({}^{-1}\)and 2 mm porous thickness the critical heat flux was reached. The following conclusions were obtained:  
* Low porous thickness increases the heat flux at the same wall superheat temperature around two times, promoting bubble formation and increasing the bubble departure rate. Besides, the abrupt increment on the wall superheat can also be prevented, thus, the critical heat flux and film boiling are avoided.
* The inlet subcooling temperature plays an important role to consider in the flow pattern and bubble formation. Higher inlet temperature condenses the small bubbles rapidly outside the porous body. However, inside the high thickness porous body, the vapor trap ability increases, thus a vapor blanket is formed.
* The thickness of the porous body is an important parameter to consider 0.2, 0.5, and 1 mm porous body presented an enhancement in comparison with the 0 mm (bare surface). However, the 2 mm porous body presented a reduction in the heat flux at the same wall superheat temperature.  
Data curation, E.S.G., Y.O. and K.E.; Funding acquisition, K.E.; Investigation, E.S.G., Y.O. and K.E.; Project administration, K.E.; Visualization, E.S.G. and Y.O.; Writing--original draft, E.S.G.; Writing--review & editing, E.S.G., Y.O., K.E., T.S., K.T., K.O. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
Data Availability StatementData openly available in a public repository that issues datasets with DOIs.  
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The authors declare no conflict of interest.