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A novel role of three dimensional graphene foam to prevent heater failure during boiling.

Ahn HS, Kim JM, Park C, Jang JW, Lee JS, Kim H, Kaviany M, Kim MH - Sci Rep (2013)

Bottom Line: The gained time by NBHT would provide the safer margin of the heat transfer and the amazing impact on the thermal system as the first report of graphene application.In addition, the CHF and boiling heat transfer performance also increase.This novel boiling phenomenon can effectively prevent heater failure because of the role played by the self-assembled three-dimensional foam-like graphene network (SFG).

View Article: PubMed Central - PubMed

Affiliation: Division of Mechanical System Engineering, Incheon National University, Incheon, Republic of Korea.

ABSTRACT
We report a novel boiling heat transfer (NBHT) in reduced graphene oxide (RGO) suspended in water (RGO colloid) near critical heat flux (CHF), which is traditionally the dangerous limitation of nucleate boiling heat transfer because of heater failure. When the heat flux reaches the maximum value (CHF) in RGO colloid pool boiling, the wall temperature increases gradually and slowly with an almost constant heat flux, contrary to the rapid wall temperature increase found during water pool boiling. The gained time by NBHT would provide the safer margin of the heat transfer and the amazing impact on the thermal system as the first report of graphene application. In addition, the CHF and boiling heat transfer performance also increase. This novel boiling phenomenon can effectively prevent heater failure because of the role played by the self-assembled three-dimensional foam-like graphene network (SFG).

No MeSH data available.


Related in: MedlinePlus

Boiling characteristics of RGO colloid and time history of the heat flux and wall temperature on the SiO2 heater.(a) Boiling curve, which is characterized by the heat flux and wall temperature, shows the water and RGO colloid boiling. At the maximum heat flux (CHF), the wall temperature in water boiling increases rapidly, however, it in RGO colloid boiling increases very slowly. (b) Wall temperature of RGO colloid boiling increases very slowly with time after heat flux reaches the CHF. The margin of time can provide the assurance of more effective and safer heat transfer condition near CHF.
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f1: Boiling characteristics of RGO colloid and time history of the heat flux and wall temperature on the SiO2 heater.(a) Boiling curve, which is characterized by the heat flux and wall temperature, shows the water and RGO colloid boiling. At the maximum heat flux (CHF), the wall temperature in water boiling increases rapidly, however, it in RGO colloid boiling increases very slowly. (b) Wall temperature of RGO colloid boiling increases very slowly with time after heat flux reaches the CHF. The margin of time can provide the assurance of more effective and safer heat transfer condition near CHF.

Mentions: The 0.0005-wt% RGO colloid is prepared (Supplementary Fig. S1a). The RGO flakes are characterized by transmission electron microscopy (TEM) and atomic force microscopy (AFM) observations (Supplementary Fig. S1b, c, d). Over 90% of the RGO flakes are observed as a monolayer. The size of the suspended RGO flakes in water measured by AFM is 0.5–1.0 μm. A steady-state heat flux is applied on the heater surface (SiO2 with a Pt-film heater) at 50- and 100-kW·m−2 increments at the saturated condition of atmospheric pressure (Supplementary Fig. S2, S3). During water boiling, CHF occurs at a heat flux of 800 kW·m−2 and a wall temperature of 150°C (Figure 1a). The wall temperature increases suddenly to 300°C within just 2 seconds. When the heat flux and wall temperature reach maximum heat flux (CHF) during boiling heat transfer, the heat transfer regime changes rapidly from nucleate boiling to film boiling, followed by CHF and the transition boiling regime (Supplementary Fig. S4). However, during RGO colloid boiling, the wall temperature starts to increase slowly at a heat flux of 1420 kW·m−2 and a wall temperature of 150°C. It takes nearly 170 minutes to reach a wall temperature of 320°C, eliminating the sudden temperature increase, which is found during water boiling. The time scale of the wall temperature increase at and after CHF differs significantly for water boiling and RGO colloid boiling (Figure 1b). The more interesting result is the 80% increase in both the CHF and BHT during the NBHT.


A novel role of three dimensional graphene foam to prevent heater failure during boiling.

Ahn HS, Kim JM, Park C, Jang JW, Lee JS, Kim H, Kaviany M, Kim MH - Sci Rep (2013)

Boiling characteristics of RGO colloid and time history of the heat flux and wall temperature on the SiO2 heater.(a) Boiling curve, which is characterized by the heat flux and wall temperature, shows the water and RGO colloid boiling. At the maximum heat flux (CHF), the wall temperature in water boiling increases rapidly, however, it in RGO colloid boiling increases very slowly. (b) Wall temperature of RGO colloid boiling increases very slowly with time after heat flux reaches the CHF. The margin of time can provide the assurance of more effective and safer heat transfer condition near CHF.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3675455&req=5

f1: Boiling characteristics of RGO colloid and time history of the heat flux and wall temperature on the SiO2 heater.(a) Boiling curve, which is characterized by the heat flux and wall temperature, shows the water and RGO colloid boiling. At the maximum heat flux (CHF), the wall temperature in water boiling increases rapidly, however, it in RGO colloid boiling increases very slowly. (b) Wall temperature of RGO colloid boiling increases very slowly with time after heat flux reaches the CHF. The margin of time can provide the assurance of more effective and safer heat transfer condition near CHF.
Mentions: The 0.0005-wt% RGO colloid is prepared (Supplementary Fig. S1a). The RGO flakes are characterized by transmission electron microscopy (TEM) and atomic force microscopy (AFM) observations (Supplementary Fig. S1b, c, d). Over 90% of the RGO flakes are observed as a monolayer. The size of the suspended RGO flakes in water measured by AFM is 0.5–1.0 μm. A steady-state heat flux is applied on the heater surface (SiO2 with a Pt-film heater) at 50- and 100-kW·m−2 increments at the saturated condition of atmospheric pressure (Supplementary Fig. S2, S3). During water boiling, CHF occurs at a heat flux of 800 kW·m−2 and a wall temperature of 150°C (Figure 1a). The wall temperature increases suddenly to 300°C within just 2 seconds. When the heat flux and wall temperature reach maximum heat flux (CHF) during boiling heat transfer, the heat transfer regime changes rapidly from nucleate boiling to film boiling, followed by CHF and the transition boiling regime (Supplementary Fig. S4). However, during RGO colloid boiling, the wall temperature starts to increase slowly at a heat flux of 1420 kW·m−2 and a wall temperature of 150°C. It takes nearly 170 minutes to reach a wall temperature of 320°C, eliminating the sudden temperature increase, which is found during water boiling. The time scale of the wall temperature increase at and after CHF differs significantly for water boiling and RGO colloid boiling (Figure 1b). The more interesting result is the 80% increase in both the CHF and BHT during the NBHT.

Bottom Line: The gained time by NBHT would provide the safer margin of the heat transfer and the amazing impact on the thermal system as the first report of graphene application.In addition, the CHF and boiling heat transfer performance also increase.This novel boiling phenomenon can effectively prevent heater failure because of the role played by the self-assembled three-dimensional foam-like graphene network (SFG).

View Article: PubMed Central - PubMed

Affiliation: Division of Mechanical System Engineering, Incheon National University, Incheon, Republic of Korea.

ABSTRACT
We report a novel boiling heat transfer (NBHT) in reduced graphene oxide (RGO) suspended in water (RGO colloid) near critical heat flux (CHF), which is traditionally the dangerous limitation of nucleate boiling heat transfer because of heater failure. When the heat flux reaches the maximum value (CHF) in RGO colloid pool boiling, the wall temperature increases gradually and slowly with an almost constant heat flux, contrary to the rapid wall temperature increase found during water pool boiling. The gained time by NBHT would provide the safer margin of the heat transfer and the amazing impact on the thermal system as the first report of graphene application. In addition, the CHF and boiling heat transfer performance also increase. This novel boiling phenomenon can effectively prevent heater failure because of the role played by the self-assembled three-dimensional foam-like graphene network (SFG).

No MeSH data available.


Related in: MedlinePlus