An experimental study on Microbubble Emission Boiling in a subcooled pool: Heat transfer characteristics and visualized presentation

Tang, Jiguo; Mo, Zhengyu; Sun, Licheng; Yan, Changqi

doi:10.1016/j.expthermflusci.2016.08.011

Cited by 20 publications

(24 citation statements)

References 24 publications

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“…Higher wall temperatures were also observed for the 10 K of subcooling, whereas in the case of ∆T sub = 20 K the temperatures were around 1 K lower compared to saturated boiling. Partial overlaying of boiling curves in nucleate boiling regime for different degrees of subcooling was also previously observed by other authors (Ando et al, 2016;Tang et al, 2017). It is claimed that average wall temperature and heat transfer mechanism at a given heat flux do not depend on the liquid subcooling (Ando et al, 2016).…”

Section: Resultssupporting

confidence: 59%

“…However, for certain degree of subcooling (∆T sub -the temperature difference between saturation temperature and bulk temperature) the so-called microbubble emission boiling (MEB) can take place. In the MEB regime heat fluxes much higher than CHF are observed even though the ∆T sat usually does not exceed 100 K. Several authors (Ando et al, 2016;Tang et al, 2017) found that MEB occurs only when the level of subcooling is exceeding 20 K. Authors Ando et al (2016) further argue that in the regime of nucleate boiling the boiling curves are overlaid on each other without depending on the liquid subcooling. It is thought that heat transfer mechanisms of nucleate boiling are not dependent on the degree of subcooling.…”

Section: Introductionmentioning

confidence: 99%

“…However, in real applications the boiling surface is most often surrounded with subcooled liquid. The degree of subcooling influences fluid properties, heat transfer mechanisms (Ando et al, 2016;Tang et al, 2017), and also the critical heat flux (Zuber, 1959;Golobič and Bergles, 1992). Therefore, the results and findings in saturated conditions cannot be directly transferred to subcooled boiling.…”

Section: Introductionmentioning

confidence: 99%

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High-Speed Infrared Thermographic Investigation of Water Subcooled Pool Boiling on Thin Metal Foils

Zupančič

Voglar

Cimerman

et al. 2016

Interfac Phenom Heat Transfer

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In this study we investigate pool boiling of water at 0, 5, 10, and 20 K of subcooling and heat fluxes up to 250 kW/m 2 . The experiments are performed on smooth 6-µm titanium foil whereas a high-speed infrared and video camera are used to measure spatio-temporal surface temperature variations and visualize growing/collapsing vapor bubbles. Results show partial overlaying of boiling curves, which means that a higher degree of subcooling does not necessarily result in a lower average wall temperature. In all cases the bubble activation temperatures in subcooled boiling are higher compared to activation temperatures in saturated boiling. Existing nucleation criteria confirm that phenomenon. This indicates that overlaying of boiling curves cannot be attributed only to some random events on the boiling surface or measurement uncertainties. Experimental data are also presented in the form of recent wall-temperature distributions. All the distributions in subcooled conditions exhibit lower skewness compared to the temperature data obtained in saturated boiling. Subcooled liquid requires larger bubble activation temperature and at the same time limits the local temperature increase. Therefore, the mass of each individual distribution is concentrated on the right side and exhibits negative skewness. This additionally confirms the usefulness of wall-temperature distributions for evaluation and comparison of pool boiling experimental data.

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Section: Resultssupporting

confidence: 59%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

High-Speed Infrared Thermographic Investigation of Water Subcooled Pool Boiling on Thin Metal Foils

Zupančič

Voglar

Cimerman

et al. 2016

Interfac Phenom Heat Transfer

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“…The experimental apparatus to study MEB is shown in Figure , which has been introduced in our previous work in detail . It is mainly composed of a water tank and a copper block.…”

Section: Experimental Systemmentioning

confidence: 99%

Experimental investigation of transition process from nucleate boiling to microbubble emission boiling under transient heating modes

Tang

Sun

et al. 2019

AIChE Journal

Self Cite

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This study investigated the transition from nucleate boiling to microbubble emission boiling (MEB) on a small heating surface under transient heating modes. During the short unstable boiling process after critical heat flux with a rapid increase in wall temperature, capillary waves were observed over the vapor film at subcooling of 30–40 K. The visualization results in this process demonstrated that the partial collapse of vapor film induced strong jet toward the heating surface and therefore avoided complete dryout thereon. This mechanism certainly plays an important role in the transition to stable MEB. Further comparison between the wall temperature and boiling states indicates that the wall temperature at onset point of stable MEB is determined by the predominance of MEB mode over film boiling in the transition process. Effects of liquid subcooling and surface oxidation on the transition process were also investigated at the same time.

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“…It is previously reported that MEB is observed when the degree of liquid subcooling is above 20 K with water. [14,17] Without stirrer, as a result, it appears that lower water level makes the liquid subcooling lower in this system and it interrupted MEB.…”

Section: E18-010-4mentioning

confidence: 88%

Advanced Boiling Cooling Technology Using a Compact Vessel with a Low Water Level

Unno

Yuki

Kibushi

et al. 2018

Transactions of The Japan Institute of Electronics Packaging

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There is a strong demand for compact cooling devices that is used for power electronics such as inverters of electric vehicles. Aiming for improving the performance of cooling devices with downsizing it, boiling heat transfer attracts a lot of attention because of its high heat transfer coefficient. However, there is few reports related to subcooled pool boiling using a compact vessel. In this study, to achieve a higher heat flux removing using a compact vessel, subcooled pool boiling was investigated by varying a water level, as well as microbubble emission boiling characteristics. As a result, the experimental result found that the onset of microbubble emission boiling is affected by the water level. Fig. 1 Boiling curves with or without microbubble emission boiling (MEB).130Next, boiling curve was investigated by varying the water level, as shown in fig. 6. Ivey and Morris correlation [18] at the 131 liquid subcooling of 35 K, which can predict CHF value in subcooled pool boiling, is also plotted with a solid line. The chained 132 lines show the same correlations at the liquid subcooling of 25 K and 45 K. As noted above, the degree of liquid subcooling 133 was temporary decreased to less than 20 K at 400 W/cm 2 with 8 mm because of a large fluctuation in liquid subcooling 134 (13 K at a maximum). Therefore, Ivey and Morris correlations were calculated at the degree of liquid subcooling of 135 35 K ± 10K. As a result, the CHF values were approximately corresponded to Ivey-Morris correlations. In this study, 136 when water level is higher than 10 mm, it was possible to keep the average degree of liquid subcooling at 35 K at 400 137 W/cm 2 . In contrast, the average degree of liquid subcooling was decreased to 33 K when water level is lower than 8 mm at 138 400 W/cm 2 . Moreover, MEB was not maintained and film boiling was observed at water level of 6 mm. Consequently, the 139 experimental result found that it is required to optimize the design of heat exchanger for keeping the degree of liquid subcooling 140

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An experimental study on Microbubble Emission Boiling in a subcooled pool: Heat transfer characteristics and visualized presentation

Cited by 20 publications

References 24 publications

High-Speed Infrared Thermographic Investigation of Water Subcooled Pool Boiling on Thin Metal Foils

High-Speed Infrared Thermographic Investigation of Water Subcooled Pool Boiling on Thin Metal Foils

Experimental investigation of transition process from nucleate boiling to microbubble emission boiling under transient heating modes

Advanced Boiling Cooling Technology Using a Compact Vessel with a Low Water Level

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