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Hyun Sun Park - One of the best experts on this subject based on the ideXlab platform.

  • effective and uniform cooling on a porous Micro Structured Surface with visualization of liquid vapor interface
    International Journal of Heat and Mass Transfer, 2019
    Co-Authors: Hyunwoo Noh, Hyun Sun Park, Junseon Yoo, Jinoh Kim, Don Koan Hwang, Dongpyo Kim, Moo Hwan Kim
    Abstract:

    Abstract This study examines cooling efficiency, uniformity, and bubble dynamics on a porous Surface. We use infrared (IR) thermometry to visualize results of temperature fields and liquid/vapor interfacial dynamics. Porous and non-porous Micro-Structured Surfaces are prepared using soft-lithography and a ceramic precursor, allylhydropolycarbosilane (AHPCS). The Surface cavities promote nucleation, and the heat transfer coefficient on the porous Surface is approximately 30% higher than that on the non-porous Surface. Additionally, the porous Surface exhibits a more uniform temperature field with lower spatial and temporal variations than the non-porous Surface. Bubble dynamics is visualized via an IR camera through the bottom side of the test specimens using the IR transparent characteristics of the substrate and Micro-structures. The porous Surface reveals higher nucleation site density and contact line density and lower equivalent bubble diameter when compared with those of the non-porous Surface, and this is consistent with more effective and uniform cooling on the porous Surface.

  • wetting characteristic of bubble on Micro pillar Structured Surface under a water pool
    Experimental Thermal and Fluid Science, 2019
    Co-Authors: Seol Ha Kim, Hyun Sun Park, Moo Hwan Kim
    Abstract:

    Abstract In this study, the contact angle of air bubbles on a Micro-Structured Surface under a water pool is experimentally investigated. A previous study “Kang and Jacobi, Equilibrium Contact Angles of Liquids on Ideal Rough Surfaces, Langmuir (2011)” adopted the work of adhesion as the additional work of the process of droplet contact on a textured Surface, and it explained the reason for failure of the classical theoretical model (Wenzel equation) in real wetting tests. We extended the above concept to bubble interaction with the textured Surface. First, the bubble contact angles on the textured Surface were modeled based on the concept of the work of adhesion in the free energy calculation. Second, the contact angle of air bubbles was measured on the bottom of test Surfaces under a water pool. The test-section Surfaces have Micro-pillars with a size of 5–40 μm prepared by the Microelectromechanical systems (MEMS) technique. The bubble contact angles were compared with both the modeled bubble shape and classical prediction (Wenzel & Cassie–Baxter equations). In addition, detail wetting features which shows wetting transition and critical wetting behavior of bubble were discussed.

  • Boiling heat transfer and critical heat flux evaluation of the pool boiling on Micro Structured Surface
    'Elsevier BV', 2018
    Co-Authors: Sh Kim, Kiyofumi Moriyama, Kim Moo Hwan, Gc Lee, Jy Kang, Hyun Sun Park
    Abstract:

    We study the effectiveness of MicroStructured Surfaces in enhancing the boiling heat transfer (BHT) and critical heat flux (CHF). A set of experiments is designed with thirteen prepared samples: twelve with a MicroStructured Surface, and one with a bare Surface. The samples are fabricated using Microelectrome-chanical systems (MEMS) techniques. The samples are tested using pool boiling experiments in saturated and atmospheric pressure conditions. The experimental results show that BHT increases with the Surface roughness, defined as the ratio of the rough Surface area to the projected area, but this enhancement gradually slows. The heat transfer coefficient of the Structured Surface is more than 300% that of the bare Surface. The increase in the heating Surface area due to the roughness ratio improves nucleate BHT due to the enhancement of convective heat transfer. The Structured Surface shows a 350% improvement in CHF over the bare Surface. However, through analysis of the capillary flow rate on the Structured Surface, a critical gap size that limits the CHF is found. The critical gap size is discussed analytically and compared with experimental data. Designs for optimal boiling performance are proposed by studying the role of MicroStructured Surfaces in both BHT and CHF. (C) 2015 Elsevier Ltd. All rights reserved.1352

  • heat flux partitioning analysis of pool boiling on Micro Structured Surface using infrared visualization
    International Journal of Heat and Mass Transfer, 2016
    Co-Authors: Seol Ha Kim, Jun Young Kang, Kiyofumi Moriyama, Hyun Sun Park, Gi Cheol Lee, Moo Hwan Kim
    Abstract:

    Abstract We study a heat flux partitioning analysis of nucleate pool boiling on MicroStructured Surface through infrared visualization technique. A heat flux partitioning analysis of the nucleate pool boiling consists of three kinds of heat flux mechanisms; convective, quenching and evaporative heat flux. It is importance of understanding the dominance among those heat flux mechanisms to fundamental study of the nucleate boiling heat transfer, but it is not clearly figured out. In this study, directly measuring the boiling parameters; bubble departure size, bubble releasing frequency, nucleation site density and bubble growth time through the infrared visualization technique, a nucleate boiling heat flux portioning analysis on pool boiling has been carried out. The experimental results indicate that sum of the three heat flux partitions from the measured boiling parameters shows good agreement with the experimentally given total heat flux. In addition, the quenching heat flux and evaporative heat flux becomes dominant at high heat flux regime by numerous bubble generation and fast bubble growth. On the MicroStructured Surface, the increased heating Surface area by the roughness ratio intactly contributes the heat transfer performance enhancement, and the area increase effect have to be reflected on the heat flux partitioning calculation. Although there are still many arguments of the heat flux portioning model analysis on pool boiling heat transfer from literatures and the methodological limitation due to the chaotic boiling phenomena, this study gives good inspiration and understanding of the boiling heat transfer mechanism and the importance of each heat transfer mechanism.

  • boiling heat transfer and critical heat flux evaluation of the pool boiling on Micro Structured Surface
    International Journal of Heat and Mass Transfer, 2015
    Co-Authors: Jun Young Kang, Kiyofumi Moriyama, Hyun Sun Park
    Abstract:

    Abstract We study the effectiveness of MicroStructured Surfaces in enhancing the boiling heat transfer (BHT) and critical heat flux (CHF). A set of experiments is designed with thirteen prepared samples: twelve with a MicroStructured Surface, and one with a bare Surface. The samples are fabricated using Microelectromechanical systems (MEMS) techniques. The samples are tested using pool boiling experiments in saturated and atmospheric pressure conditions. The experimental results show that BHT increases with the Surface roughness, defined as the ratio of the rough Surface area to the projected area, but this enhancement gradually slows. The heat transfer coefficient of the Structured Surface is more than 300% that of the bare Surface. The increase in the heating Surface area due to the roughness ratio improves nucleate BHT due to the enhancement of convective heat transfer. The Structured Surface shows a 350% improvement in CHF over the bare Surface. However, through analysis of the capillary flow rate on the Structured Surface, a critical gap size that limits the CHF is found. The critical gap size is discussed analytically and compared with experimental data. Designs for optimal boiling performance are proposed by studying the role of MicroStructured Surfaces in both BHT and CHF.

Qingliang Zhao - One of the best experts on this subject based on the ideXlab platform.

  • water assisted pulsed laser machining of Micro Structured Surface on cvd diamond coating tools
    Journal of Manufacturing Processes, 2020
    Co-Authors: Bing Guo, Qingliang Zhao, Jun Zhang, Han Liu, Amr Monier, Jinhu Wang
    Abstract:

    Abstract In this paper, a water assisted pulsed laser machining with mist spray was investigated for machining the Micro-structures on chemical vapor deposition (CVD) diamond coating tools. Firstly, the effect of water assisted condition on the machining quality and the transformation of Gauusian laser beam was analyzed. The theoretical calculation method of the shifted value of laser beam spot radius and defocusing quantity in the water assisted laser machining was presented. And then the effects of laser machining parameters included the laser power, the scanning speed, the scanning times and the scanning pitch were discussed in view of the ablation width, ablation depth, material removal rate and machined Surface topography. Finally, three kind of Micro-structures included Micro groove array and cross-scale composite Micro-structures were machined successfully on the CVD diamond coating tools by the developed water assisted pulsed laser machining method.

  • mechanical truing of v shape diamond wheels for Micro Structured Surface grinding
    The International Journal of Advanced Manufacturing Technology, 2015
    Co-Authors: Bing Guo, Qingliang Zhao
    Abstract:

    An on-machine mechanical truing method with rotary green silicon carbide (GC) roller to precision shape and prepare V-shape diamond wheels for MicroStructured Surface grinding was proposed. The effects of truing parameters on trued wheel profile accuracy were investigated. The experimental results showed that the feed direction of GC roller had a remarkable effect on truing accuracy. The V-tip radius of trued wheel was reduced with the increase of the GC roller speed or the decrease of the grinding wheel speed, truing depth per pass, feed rate, and the grain size of GC roller. The V-shape diamond wheel with less than 18-μm V-tip radius and 0.6-μm run-out (center zone of wheel) was produced by parameter optimization. Finally, the V-groove array was ground on silicon nitride mold material by the trued diamond wheels. Although the V-tip of diamond wheel can be trued to less than 18 μm, the smallest corner radius, which was obtained in the first ground groove, was still bigger than 46 μm due to the unavoidable wear of diamond wheel in the grinding process of hard mold material.

  • on machine dry electric discharge truing of diamond wheels for Micro Structured Surfaces grinding
    International Journal of Machine Tools & Manufacture, 2015
    Co-Authors: Bing Guo, Qingliang Zhao
    Abstract:

    Abstract Precision grinding with diamond wheels gives a promising alternative to achieve high quality Micro-Structured Surfaces on optical molds. However, it is difficult to true these diamond wheels efficiently, because of the remarkable resistance property and the geometrical limitation of small wheel profile. In this paper, an on-machine dry-EDT method to precision shape and prepare diamond wheels with various profiles was proposed for Micro-Structured Surface grinding. Firstly, the fundamental truing errors were analyzed based on the dry-EDT kinematics. And then the capabilities of dry-EDT truing for high abrasive concentration metal bonded diamond wheels were presented. Next, the effects of kinematic parameters variables on trued wheel profile accuracy were investigated. Finally, the Micro-Structured Surfaces on SiC ceramic and tungsten carbide WC were ground by these trued diamond wheels. The experiments results showed that the arc-shaped diamond wheel (diameter of 200 mm) with 4 μm profile error ( PV ) and 1.0023 mm profile radius, and the V-shaped diamond wheel with 22.5 μm V-tip radius and 120.03° profile angle could be obtained by on-machine dry EDT. The kinematic parameters of dry-EDT have an important influence on truing profile accuracy of diamond wheels, especially for the tip of V-shaped wheel. The subsequent grinding show that the edge radius of V groove array on SiC is less than 2 μm, while the radius of included corner is around 55 μm. The PV error of ground arc groove array on WC is less than 5 μm. The Surface roughness of ground Micro-Structured Surface R a is 142 nm and 97 nm for SiC and WC, respectively.

  • Surface Micro structuring of coarse grained diamond wheels by nanosecond pulsed laser for improving grinding performance
    International Journal of Precision Engineering and Manufacturing, 2014
    Co-Authors: Qingliang Zhao, Xin Yu
    Abstract:

    The conditioned coarse-grained diamond wheels are able to achieve the identical Surface roughness, higher form accuracy and larger grinding rate when compared to the traditional fine-grained diamond wheels. However, deeper subSurface damage could be inevitably introduced due to the flat tops of the coarse diamond grains. This work presents a Micro-structuring method for coarse-grained diamond wheels by means of nanosecond pulsed laser, which allows the generation of Micro grooves arrays on the coarse diamond grains distributed on the whole grinding wheel cylindrical Surface. The influence of laser parameters such as focal point shift, laser power, scanning speed and scanning passes on Micro-Structured Surface was investigated, and then the laser machining process was optimized in fabricating uniform and continuous Micro-structures. The grinding experiments indicate that, when compared to the non-Micro-Structured grinding wheels, the subSurface cracks depth of ground optical glass was reduced effectually by using the Micro-Structured coarse-grained diamond wheels.

Kiyofumi Moriyama - One of the best experts on this subject based on the ideXlab platform.

  • control of minimum film boiling quench temperature of small spheres with Micro Structured Surface
    International Journal of Multiphase Flow, 2018
    Co-Authors: Kang Junyoung, Kiyofumi Moriyama, Lee Gi Cheol, Massoud Kaviany, Kim Moo Hwan
    Abstract:

    Abstract The control of minimum film-boiling quench temperature, TMFB is investigated in water quenching experiments with several Micro-Structured Surfaces on small spheres (diameters 10 and 15 mm) under saturation temperature Tsat and 1 atm. The results show increase in TMFB and is related to the temperature drop across the Micro-structures, and affected by its effective thermal conductivity 〈k〉, height L, and base diameter D, based on the fin theory. The local temperature drop of Surface Microstructure depends on the hybrid Biot number, B i h = h L 2 / ( 〈 k 〉 D ) , where h is the heat transfer coefficient. The liquid–solid contact depends on this Microstructure-tip temperature, and a model for TMFB with synthetic Surface Micro-structure is proposed and compared with the experimental results. The theoretical limit of maximum TMFB (under saturated water at 1 atm) for Surface Micro-Structured small sphere is reached when Bih is beyond 102.

  • Boiling heat transfer and critical heat flux evaluation of the pool boiling on Micro Structured Surface
    'Elsevier BV', 2018
    Co-Authors: Sh Kim, Kiyofumi Moriyama, Kim Moo Hwan, Gc Lee, Jy Kang, Hyun Sun Park
    Abstract:

    We study the effectiveness of MicroStructured Surfaces in enhancing the boiling heat transfer (BHT) and critical heat flux (CHF). A set of experiments is designed with thirteen prepared samples: twelve with a MicroStructured Surface, and one with a bare Surface. The samples are fabricated using Microelectrome-chanical systems (MEMS) techniques. The samples are tested using pool boiling experiments in saturated and atmospheric pressure conditions. The experimental results show that BHT increases with the Surface roughness, defined as the ratio of the rough Surface area to the projected area, but this enhancement gradually slows. The heat transfer coefficient of the Structured Surface is more than 300% that of the bare Surface. The increase in the heating Surface area due to the roughness ratio improves nucleate BHT due to the enhancement of convective heat transfer. The Structured Surface shows a 350% improvement in CHF over the bare Surface. However, through analysis of the capillary flow rate on the Structured Surface, a critical gap size that limits the CHF is found. The critical gap size is discussed analytically and compared with experimental data. Designs for optimal boiling performance are proposed by studying the role of MicroStructured Surfaces in both BHT and CHF. (C) 2015 Elsevier Ltd. All rights reserved.1352

  • heat flux partitioning analysis of pool boiling on Micro Structured Surface using infrared visualization
    International Journal of Heat and Mass Transfer, 2016
    Co-Authors: Seol Ha Kim, Jun Young Kang, Kiyofumi Moriyama, Hyun Sun Park, Gi Cheol Lee, Moo Hwan Kim
    Abstract:

    Abstract We study a heat flux partitioning analysis of nucleate pool boiling on MicroStructured Surface through infrared visualization technique. A heat flux partitioning analysis of the nucleate pool boiling consists of three kinds of heat flux mechanisms; convective, quenching and evaporative heat flux. It is importance of understanding the dominance among those heat flux mechanisms to fundamental study of the nucleate boiling heat transfer, but it is not clearly figured out. In this study, directly measuring the boiling parameters; bubble departure size, bubble releasing frequency, nucleation site density and bubble growth time through the infrared visualization technique, a nucleate boiling heat flux portioning analysis on pool boiling has been carried out. The experimental results indicate that sum of the three heat flux partitions from the measured boiling parameters shows good agreement with the experimentally given total heat flux. In addition, the quenching heat flux and evaporative heat flux becomes dominant at high heat flux regime by numerous bubble generation and fast bubble growth. On the MicroStructured Surface, the increased heating Surface area by the roughness ratio intactly contributes the heat transfer performance enhancement, and the area increase effect have to be reflected on the heat flux partitioning calculation. Although there are still many arguments of the heat flux portioning model analysis on pool boiling heat transfer from literatures and the methodological limitation due to the chaotic boiling phenomena, this study gives good inspiration and understanding of the boiling heat transfer mechanism and the importance of each heat transfer mechanism.

  • boiling heat transfer and critical heat flux evaluation of the pool boiling on Micro Structured Surface
    International Journal of Heat and Mass Transfer, 2015
    Co-Authors: Jun Young Kang, Kiyofumi Moriyama, Hyun Sun Park
    Abstract:

    Abstract We study the effectiveness of MicroStructured Surfaces in enhancing the boiling heat transfer (BHT) and critical heat flux (CHF). A set of experiments is designed with thirteen prepared samples: twelve with a MicroStructured Surface, and one with a bare Surface. The samples are fabricated using Microelectromechanical systems (MEMS) techniques. The samples are tested using pool boiling experiments in saturated and atmospheric pressure conditions. The experimental results show that BHT increases with the Surface roughness, defined as the ratio of the rough Surface area to the projected area, but this enhancement gradually slows. The heat transfer coefficient of the Structured Surface is more than 300% that of the bare Surface. The increase in the heating Surface area due to the roughness ratio improves nucleate BHT due to the enhancement of convective heat transfer. The Structured Surface shows a 350% improvement in CHF over the bare Surface. However, through analysis of the capillary flow rate on the Structured Surface, a critical gap size that limits the CHF is found. The critical gap size is discussed analytically and compared with experimental data. Designs for optimal boiling performance are proposed by studying the role of MicroStructured Surfaces in both BHT and CHF.

Geok Soon Hong - One of the best experts on this subject based on the ideXlab platform.

  • ductile regime machining for fast tool servo diamond turning of Micro Structured Surfaces on brittle materials
    Advanced Materials Research, 2012
    Co-Authors: Y S Wong, Geok Soon Hong
    Abstract:

    Micro-Structured Surfaces on brittle materials, e.g. ceramic and glass, are gaining increasing application in a range of areas. In this paper, fast tool servo (FTS) diamond turning has been applied to machine Micro-Structured Surfaces on brittle materials and the machined Surfaces has been observed to study its machining mechanism. A machining model is presented to enable ductile-regime machining of the brittle material. Based on the model, machining characteristics can be predicted for given cutting conditions. Experimental investigation on machining of a Micro-Structured Surface verified that ductile-regime machining can be ensured on the entire Surface through path planning simulation based on the machining model.

  • a novel method for determination of the subSurface damage depth in diamond turning of brittle materials
    International Journal of Machine Tools & Manufacture, 2011
    Co-Authors: Y S Wong, Geok Soon Hong
    Abstract:

    Abstract Micro-Structured Surfaces on brittle materials, e.g. ceramic and glass, are gaining increasing industrial applications such as optics, semiconductor and biomedical. However, these materials tend to be damaged with brittle fracture in machining. To generate crack-free Surfaces, ductile-regime machining should be maintained for the entire Micro-Structured Surface. In ductile-regime machining the material is removed by both plastic deformation and brittle fracture, but the cracks produced are prevented from extending into the finished Surface. In this paper, a machining model has been developed for fast tool servo (FTS) diamond turning of Micro-Structured Surfaces on brittle materials. Based on the model, a damaged region analysis method (DRAM) is proposed to determine the subSurface damage depth ( C m ) by analyzing the Surface damaged region of a machined Micro-Structured Surface with sinusoidal wave along radial direction. Only one Micro-Structured Surface is required to be machined to obtain C m , which greatly reduces the effort for determination of C m . With C m , the maximum feedrate for machining a crack-free Micro-Structured Surface can be determined. Machining experiments have verified the validity of DRAM.

Moo Hwan Kim - One of the best experts on this subject based on the ideXlab platform.

  • enhanced condensation on a biphilic zigzag Surface due to self arrangement of crystals on a Micro Structured Surface
    International Journal of Heat and Mass Transfer, 2021
    Co-Authors: Taeyang Han, Younghyun Choi, Moo Hwan Kim
    Abstract:

    Abstract Applying Micro-nano hierarchical structures or hydrophilic patterns on superhydrophobic Surfaces has showed the potential to increase the condensation efficiency by promoting the coalescence-induced jumping. In this study, the crystal self-arrangement is demonstrated using a capillary flow to combine the advantages of the hierarchical structures and the biphilic wettability for the further enhancement of the condensation efficiency. Such flow transports the crystals to the inner tips of the V-shapes during the evaporation of an ethanol-water film on the zigzag Structured Surface. These crystals induce the condensations inside the V-shapes that guide the condensed droplets to the gap between the zigzag structures, which promotes the coalescence between the condensed droplets. Consequently, the developed Surface increases the jumping frequency by up to 1385%, and the cumulative volume of the jumping droplets and the heat transfer coefficient on the developed Surface are approximately 2.2 and 2.7 times higher than that of the state-of-the-art superhydrophobic Surface. Our findings pave the way for enhancing the efficiency of the jumping-mode condensation for diverse applications by providing a scalable method, which maximizes the profits that the hierarchical structures and the biphilic wettability give.

  • effective and uniform cooling on a porous Micro Structured Surface with visualization of liquid vapor interface
    International Journal of Heat and Mass Transfer, 2019
    Co-Authors: Hyunwoo Noh, Hyun Sun Park, Junseon Yoo, Jinoh Kim, Don Koan Hwang, Dongpyo Kim, Moo Hwan Kim
    Abstract:

    Abstract This study examines cooling efficiency, uniformity, and bubble dynamics on a porous Surface. We use infrared (IR) thermometry to visualize results of temperature fields and liquid/vapor interfacial dynamics. Porous and non-porous Micro-Structured Surfaces are prepared using soft-lithography and a ceramic precursor, allylhydropolycarbosilane (AHPCS). The Surface cavities promote nucleation, and the heat transfer coefficient on the porous Surface is approximately 30% higher than that on the non-porous Surface. Additionally, the porous Surface exhibits a more uniform temperature field with lower spatial and temporal variations than the non-porous Surface. Bubble dynamics is visualized via an IR camera through the bottom side of the test specimens using the IR transparent characteristics of the substrate and Micro-structures. The porous Surface reveals higher nucleation site density and contact line density and lower equivalent bubble diameter when compared with those of the non-porous Surface, and this is consistent with more effective and uniform cooling on the porous Surface.

  • wetting characteristic of bubble on Micro pillar Structured Surface under a water pool
    Experimental Thermal and Fluid Science, 2019
    Co-Authors: Seol Ha Kim, Hyun Sun Park, Moo Hwan Kim
    Abstract:

    Abstract In this study, the contact angle of air bubbles on a Micro-Structured Surface under a water pool is experimentally investigated. A previous study “Kang and Jacobi, Equilibrium Contact Angles of Liquids on Ideal Rough Surfaces, Langmuir (2011)” adopted the work of adhesion as the additional work of the process of droplet contact on a textured Surface, and it explained the reason for failure of the classical theoretical model (Wenzel equation) in real wetting tests. We extended the above concept to bubble interaction with the textured Surface. First, the bubble contact angles on the textured Surface were modeled based on the concept of the work of adhesion in the free energy calculation. Second, the contact angle of air bubbles was measured on the bottom of test Surfaces under a water pool. The test-section Surfaces have Micro-pillars with a size of 5–40 μm prepared by the Microelectromechanical systems (MEMS) technique. The bubble contact angles were compared with both the modeled bubble shape and classical prediction (Wenzel & Cassie–Baxter equations). In addition, detail wetting features which shows wetting transition and critical wetting behavior of bubble were discussed.

  • heat flux partitioning analysis of pool boiling on Micro Structured Surface using infrared visualization
    International Journal of Heat and Mass Transfer, 2016
    Co-Authors: Seol Ha Kim, Jun Young Kang, Kiyofumi Moriyama, Hyun Sun Park, Gi Cheol Lee, Moo Hwan Kim
    Abstract:

    Abstract We study a heat flux partitioning analysis of nucleate pool boiling on MicroStructured Surface through infrared visualization technique. A heat flux partitioning analysis of the nucleate pool boiling consists of three kinds of heat flux mechanisms; convective, quenching and evaporative heat flux. It is importance of understanding the dominance among those heat flux mechanisms to fundamental study of the nucleate boiling heat transfer, but it is not clearly figured out. In this study, directly measuring the boiling parameters; bubble departure size, bubble releasing frequency, nucleation site density and bubble growth time through the infrared visualization technique, a nucleate boiling heat flux portioning analysis on pool boiling has been carried out. The experimental results indicate that sum of the three heat flux partitions from the measured boiling parameters shows good agreement with the experimentally given total heat flux. In addition, the quenching heat flux and evaporative heat flux becomes dominant at high heat flux regime by numerous bubble generation and fast bubble growth. On the MicroStructured Surface, the increased heating Surface area by the roughness ratio intactly contributes the heat transfer performance enhancement, and the area increase effect have to be reflected on the heat flux partitioning calculation. Although there are still many arguments of the heat flux portioning model analysis on pool boiling heat transfer from literatures and the methodological limitation due to the chaotic boiling phenomena, this study gives good inspiration and understanding of the boiling heat transfer mechanism and the importance of each heat transfer mechanism.