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Spray cooling characteristics of nanofluids for electronic power devices.

Hsieh SS, Leu HY, Liu HH - Nanoscale Res Lett (2015)

Bottom Line: The performance of a single spray for electronic power devices using deionized (DI) water and pure silver (Ag) particles as well as multi-walled carbon nanotube (MCNT) particles, respectively, is studied herein.The tests are performed with a flat horizontal heated surface using a nozzle diameter of 0.5 mm with a definite nozzle-to-target surface distance of 25 mm.The heat transfer removal rate can reach up to 274 W/cm(2) with the corresponding CHF enhancement ratio of 2.4 for the Ag/water nanofluids present at a volume fraction of 0.0075% with a low mass flux of 11.9 × 10(-4) kg/cm(2)s.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical and Electromechanical Engineering, National Sun Yat-Sen University, Kaohsiung, 80424 Taiwan.

ABSTRACT
The performance of a single spray for electronic power devices using deionized (DI) water and pure silver (Ag) particles as well as multi-walled carbon nanotube (MCNT) particles, respectively, is studied herein. The tests are performed with a flat horizontal heated surface using a nozzle diameter of 0.5 mm with a definite nozzle-to-target surface distance of 25 mm. The effects of nanoparticle volume fraction and mass flow rate of the liquid on the surface heat flux, including critical heat flux (CHF), are explored. Both steady state and transient data are collected for the two-phase heat transfer coefficient, boiling curve/ cooling history, and the corresponding CHF. The heat transfer removal rate can reach up to 274 W/cm(2) with the corresponding CHF enhancement ratio of 2.4 for the Ag/water nanofluids present at a volume fraction of 0.0075% with a low mass flux of 11.9 × 10(-4) kg/cm(2)s.

No MeSH data available.


Related in: MedlinePlus

Base fluid (DI water) cooling curve (boiling curves included).
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Fig4: Base fluid (DI water) cooling curve (boiling curves included).

Mentions: For DI water, low mass flux varying from 6.57 and 11.90 × 10−4 kg/cm2s and temperature differences for 60°C to 280°C, the cooling curves were measured. These data were used as reference data to assess the heat transfer/cooling performance of nanofluids. Typical results, shown in Figure 4, represent the cooling history of the surface temperature with DI water (numerals indicate the cooling regime). Also included in Figure 4 are the corresponding boiling curves. For Figure 4, the cooling rate in the stable film boiling regime increases with the increase in working fluid mass flux. The onset of the transition boiling was identified by the change in the cooling rate (slope change) at 180°C (G = 8.92 × 10−4 kg/cm2s); at this temperature, it takes about 120 s for DI water from the start. As the surface temperature decreases from Leidenfrost in the transition boiling regime, the cooling rate increases as more efficient surface wetting and boiling occur. At the lower temperature boundary of the transition boiling regime, where the entire surface becomes occupied by wetting, the cooling rate reaches a maximum (so called CHF). This maximum heat flux can be seen from the steepest portion of the cooling curves in Figure 4. Below CHF (e.g. G = 8.92 × 10−4 kg/cm2s), the cooling rate in nucleate boiling decreases with the decreasing surface temperature. The lower temperature boundary of the nucleate boiling is determined by the minimum wall superheat (ΔT = 18°C) required to maintain vapor bubble nucleation and growth within the impinging droplets. Finally (after about 290 s), the film evaporation or single-phase forced convection will exist below the boundary where the heat flux is about 45 W/cm2 at G = 8.92 × 10−4 kg/cm2s.Figure 4


Spray cooling characteristics of nanofluids for electronic power devices.

Hsieh SS, Leu HY, Liu HH - Nanoscale Res Lett (2015)

Base fluid (DI water) cooling curve (boiling curves included).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4385298&req=5

Fig4: Base fluid (DI water) cooling curve (boiling curves included).
Mentions: For DI water, low mass flux varying from 6.57 and 11.90 × 10−4 kg/cm2s and temperature differences for 60°C to 280°C, the cooling curves were measured. These data were used as reference data to assess the heat transfer/cooling performance of nanofluids. Typical results, shown in Figure 4, represent the cooling history of the surface temperature with DI water (numerals indicate the cooling regime). Also included in Figure 4 are the corresponding boiling curves. For Figure 4, the cooling rate in the stable film boiling regime increases with the increase in working fluid mass flux. The onset of the transition boiling was identified by the change in the cooling rate (slope change) at 180°C (G = 8.92 × 10−4 kg/cm2s); at this temperature, it takes about 120 s for DI water from the start. As the surface temperature decreases from Leidenfrost in the transition boiling regime, the cooling rate increases as more efficient surface wetting and boiling occur. At the lower temperature boundary of the transition boiling regime, where the entire surface becomes occupied by wetting, the cooling rate reaches a maximum (so called CHF). This maximum heat flux can be seen from the steepest portion of the cooling curves in Figure 4. Below CHF (e.g. G = 8.92 × 10−4 kg/cm2s), the cooling rate in nucleate boiling decreases with the decreasing surface temperature. The lower temperature boundary of the nucleate boiling is determined by the minimum wall superheat (ΔT = 18°C) required to maintain vapor bubble nucleation and growth within the impinging droplets. Finally (after about 290 s), the film evaporation or single-phase forced convection will exist below the boundary where the heat flux is about 45 W/cm2 at G = 8.92 × 10−4 kg/cm2s.Figure 4

Bottom Line: The performance of a single spray for electronic power devices using deionized (DI) water and pure silver (Ag) particles as well as multi-walled carbon nanotube (MCNT) particles, respectively, is studied herein.The tests are performed with a flat horizontal heated surface using a nozzle diameter of 0.5 mm with a definite nozzle-to-target surface distance of 25 mm.The heat transfer removal rate can reach up to 274 W/cm(2) with the corresponding CHF enhancement ratio of 2.4 for the Ag/water nanofluids present at a volume fraction of 0.0075% with a low mass flux of 11.9 × 10(-4) kg/cm(2)s.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical and Electromechanical Engineering, National Sun Yat-Sen University, Kaohsiung, 80424 Taiwan.

ABSTRACT
The performance of a single spray for electronic power devices using deionized (DI) water and pure silver (Ag) particles as well as multi-walled carbon nanotube (MCNT) particles, respectively, is studied herein. The tests are performed with a flat horizontal heated surface using a nozzle diameter of 0.5 mm with a definite nozzle-to-target surface distance of 25 mm. The effects of nanoparticle volume fraction and mass flow rate of the liquid on the surface heat flux, including critical heat flux (CHF), are explored. Both steady state and transient data are collected for the two-phase heat transfer coefficient, boiling curve/ cooling history, and the corresponding CHF. The heat transfer removal rate can reach up to 274 W/cm(2) with the corresponding CHF enhancement ratio of 2.4 for the Ag/water nanofluids present at a volume fraction of 0.0075% with a low mass flux of 11.9 × 10(-4) kg/cm(2)s.

No MeSH data available.


Related in: MedlinePlus