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Yong Tang - One of the best experts on this subject based on the ideXlab platform.

  • Thermal performance enhancement of an ultra-thin flattened Heat pipe with multiple wick structure
    Applied Thermal Engineering, 2021
    Co-Authors: Heng Tang, Changxing Weng, Yong Tang
    Abstract:

    Abstract Low Heat-Transport Capability has been the biggest problem that has retarded the development of ultra-thin Heat pipes (UFHPs). In this study, a high-performance multiple mesh wick structure, fabricated by oxidation treatment and sintering, was proposed for enhancing the thermal performance of UFHPs. The effects of various Heat inputs and flattened thicknesses on the thermal performance of the UFHPs with copper mesh wicks were investigated and analysed, and the experimental results compared with those of UFHPs with conventional sintered powder wicks. The experimental results demonstrated that the Heat-Transport Capability of the UFHP with the mesh wick could be effectively enhanced by oxidation, and the oxidized mesh wicks had the same capillary performance as sintered powder wicks. The temperature difference of the UFHP with the oxidized mesh wick was significantly lower than that of the UFHP with the un-oxidized mesh wick and sintered powder wick under identical Heat input. Moreover, the performance improvement of the UFHP with the mesh wick was more significant after treatment with chemical oxidation when the flattened thickness was larger, the ultimate Heat-Transport capabilities of the UFHPs with a flattened thickness of 1.2 mm increased by 6 W and 9 W, respectively, compared with those with a flattened thickness of 1.0 mm.

Zhixin Zeng - One of the best experts on this subject based on the ideXlab platform.

  • Investigation of ultra-thin flattened Heat pipes with sintered wick structure
    Applied Thermal Engineering, 2015
    Co-Authors: Yuying Yan, Zhixin Zeng
    Abstract:

    Abstract This study proposes a novel sintered wick structure called bilateral arch-shaped sintered wick (BASSW) for the improvement of the ultra-thin Heat pipes (UTHPs). The bilateral arch-shaped wick was sintered at the middle of its copper container and the vapor flow channels are located on both sides. The sintered wick was manufactured with several paramount parameters including maximum wick thickness, flattened thickness, and copper powder particle size fully controlled. An experimental apparatus was set up to investigate the thermal performance of the UTHP samples under the impacts of incremental Heat loads. The effects of each processing parameter on the thermal performance of the UTHP samples were analyzed and compared with a mathematical model incorporating effects of the evaporation and condensation Heat transfer in a copper-water wick. Results indicate that the most critical factor for thermal performance of UTHP is flattened thickness, as it decreases, the Heat Transport Capability drastically decreases and the thermal resistance increases. The maximum wick thickness affects the evaporation thermal resistances by the variation of evaporation area of the liquid–vapor interface, and particle size affects the Heat Transport Capability by the variation of the porosity of the wick structure. The thermal resistances of the evaporator and condenser sections are consistent with the mathematical model before dry out occurs. The total thermal resistances of the UTHP samples range from 0.02 K/W to 0.60 K/W, and the maximum Heat Transport Capability can reach as high as 25 W.

Heng Tang - One of the best experts on this subject based on the ideXlab platform.

  • Thermal performance enhancement of an ultra-thin flattened Heat pipe with multiple wick structure
    Applied Thermal Engineering, 2021
    Co-Authors: Heng Tang, Changxing Weng, Yong Tang
    Abstract:

    Abstract Low Heat-Transport Capability has been the biggest problem that has retarded the development of ultra-thin Heat pipes (UFHPs). In this study, a high-performance multiple mesh wick structure, fabricated by oxidation treatment and sintering, was proposed for enhancing the thermal performance of UFHPs. The effects of various Heat inputs and flattened thicknesses on the thermal performance of the UFHPs with copper mesh wicks were investigated and analysed, and the experimental results compared with those of UFHPs with conventional sintered powder wicks. The experimental results demonstrated that the Heat-Transport Capability of the UFHP with the mesh wick could be effectively enhanced by oxidation, and the oxidized mesh wicks had the same capillary performance as sintered powder wicks. The temperature difference of the UFHP with the oxidized mesh wick was significantly lower than that of the UFHP with the un-oxidized mesh wick and sintered powder wick under identical Heat input. Moreover, the performance improvement of the UFHP with the mesh wick was more significant after treatment with chemical oxidation when the flattened thickness was larger, the ultimate Heat-Transport capabilities of the UFHPs with a flattened thickness of 1.2 mm increased by 6 W and 9 W, respectively, compared with those with a flattened thickness of 1.0 mm.

Yuying Yan - One of the best experts on this subject based on the ideXlab platform.

  • Investigation of ultra-thin flattened Heat pipes with sintered wick structure
    Applied Thermal Engineering, 2015
    Co-Authors: Yuying Yan, Zhixin Zeng
    Abstract:

    Abstract This study proposes a novel sintered wick structure called bilateral arch-shaped sintered wick (BASSW) for the improvement of the ultra-thin Heat pipes (UTHPs). The bilateral arch-shaped wick was sintered at the middle of its copper container and the vapor flow channels are located on both sides. The sintered wick was manufactured with several paramount parameters including maximum wick thickness, flattened thickness, and copper powder particle size fully controlled. An experimental apparatus was set up to investigate the thermal performance of the UTHP samples under the impacts of incremental Heat loads. The effects of each processing parameter on the thermal performance of the UTHP samples were analyzed and compared with a mathematical model incorporating effects of the evaporation and condensation Heat transfer in a copper-water wick. Results indicate that the most critical factor for thermal performance of UTHP is flattened thickness, as it decreases, the Heat Transport Capability drastically decreases and the thermal resistance increases. The maximum wick thickness affects the evaporation thermal resistances by the variation of evaporation area of the liquid–vapor interface, and particle size affects the Heat Transport Capability by the variation of the porosity of the wick structure. The thermal resistances of the evaporator and condenser sections are consistent with the mathematical model before dry out occurs. The total thermal resistances of the UTHP samples range from 0.02 K/W to 0.60 K/W, and the maximum Heat Transport Capability can reach as high as 25 W.

C Wilson - One of the best experts on this subject based on the ideXlab platform.

  • Heat Transport Capability and fluid flow neutron radiography of three dimensional oscillating Heat pipes
    Journal of Heat Transfer-transactions of The Asme, 2010
    Co-Authors: B Borgmeyer, C Wilson, R A Winholtz, David L Jacobson, Daniel S Hussey
    Abstract:

    An experimental investigation into the parameters affecting Heat Transport in two three-dimensional oscillating Heat pipes (OHPs) was implemented. A three-dimensional OHP is one in which the center axis of the circular channels containing the internal working fluid do not lie in the same plane. This novel design allows for more turns in a more compact size. The OHPs in the current investigation is made of copper tubings (3.175 mm outside diameter, 1.65 mm inside diameter) wrapped in a three-dimensional fashion around two copper spreaders that act as the evaporator and condenser. The two OHPs have 10 and 20 turns in both the evaporator and condenser. The 20-turn OHP was filled to 50% of the total volume with a high performance liquid chromatography grade water. Transient and steady state temperature data were recorded at different locations for various parameters. Parameters such as Heat input, operating temperature, and filling ratio were varied to determine its effect on the overall Heat Transport. Neutron radiography was simultaneously implemented to create images of the internal working fluid flow at a rate of 30 frames per second. Results show the average temperature drop from the evaporator to condenser decreases at higher Heat inputs due to an increase in temperature throughout the condenser region due to greater oscillations. These large oscillations were visually observed using neutron radiography. As the operating temperature is increased, the thermal resistance is reduced. A decrease in filling ratio tends to create more steady fluid motion; however, the Heat transfer performance is reduced.

  • Heat Transport Capability and fluid flow neutron radiography of three dimensional oscillating Heat pipes
    ASME 2008 Heat Transfer Summer Conference collocated with the Fluids Engineering Energy Sustainability and 3rd Energy Nanotechnology Conferences, 2008
    Co-Authors: B Borgmeyer, C Wilson, R A Winholtz, David L Jacobson, Daniel S Hussey
    Abstract:

    An experimental investigation into the parameters affecting Heat Transport in two three-dimensional oscillating Heat pipes (OHP) was implemented. A three-dimensional OHP is one in which the center axis of the circular channels containing the internal working fluid do not lie in the same plane. This novel design allows for more turns in a more compact size. The OHPs in the current investigation is made of copper tubing (3.175 mm OD, 1.65 mm ID) wrapped in a three-dimensional fashion around two copper spreaders that act as the evaporator and condenser. The two OHPs have 10 and 20 turns in both the evaporator and condenser. The 20 Turn OHP was filled to 50% of the total volume with high performance liquid chromatography (HPLC) grade water. Transient and steady state temperature data was recorded at different locations for various parameters. Parameters such as Heat input, operating temperature, and filling ratio were varied to determine its effect on overall Heat Transport. Neutron radiography was simultaneously implemented to create images of the internal working fluid flow at a rate of 30 frames per second (fps). Results show the average temperature drop from the evaporator to condenser decreases at higher Heat inputs due to an increase in temperature in the condenser region caused by greater oscillations. These large oscillations were visually observed using neutron radiography. As the operating temperature is increased, the thermal resistance is reduced due to increased fluid flow caused by changes in fluid properties. A decrease in filling ratio tends to create more steady fluid motion; however, the Heat transfer performance is reduced.Copyright © 2008 by ASME

  • an experimental investigation of Heat Transport Capability in a nanofluid oscillating Heat pipe
    Journal of Heat Transfer-transactions of The Asme, 2006
    Co-Authors: C Wilson, Qingsong Yu, K Park, U S Choi, Murli Tirumala
    Abstract:

    An experimental investigation of a nanofluid oscillating Heat pipe (OHP) was conducted to determine the nanofluid effect on the Heat Transport Capability in an OHP. The nanofluid consisted of HPLC grade water and 1.0 vol % diamond nanoparticles of 5-50 nm. These diamond nanoparticles settle down in the motionless base fluid. However, the oscillating motion of the OHP suspends the diamond nanoparticles in the working fluid. Experimental results show that the Heat Transport Capability of the OHP significantly increased when it was charged with the nanofluid at a filling ratio of 50%. It was found that the Heat Transport Capability of the OHP depends on the operating temperature. The investigated OHP could reach a thermal resistance of 0.03° C/W at a Heat input of 336 W. The nanofluid OHP investigated here provides a new approach in designing a highly efficient next generation of Heat pipe cooling devices.

  • effect of nanofluid on the Heat Transport Capability in an oscillating Heat pipe
    Applied Physics Letters, 2006
    Co-Authors: C Wilson, Qingsong Yu, K Park, B Borgmeyer, S U S Choi, Murli Tirumala
    Abstract:

    By combining nanofluids with thermally excited oscillating motion in an oscillating Heat pipe (OHP), we developed an ultrahigh-performance cooling device, called the nanofluid oscillating Heat pipe. Experimental results show that when the OHP is charged with nanofluid, Heat Transport Capability significantly increases. For example, at the input power of 80.0W, diamond nanofluid can reduce the temperature difference between the evaporator and the condenser from 40.9to24.3°C. This study will accelerate the development of a highly efficient cooling device for ultrahigh-Heat-flux electronic systems.

  • High Thermal Conductivity of Diamond Nanofluids and its Effect on the Heat Transport Capability in an Oscillating Heat Pipe
    Heat Transfer Volume 2, 2006
    Co-Authors: C Wilson, K Park
    Abstract:

    In Heat exchangers and liquid cooling devices the thermal conductivity of the liquid is an important factor in their design. Recently it has been shown that adding small amounts of nanoparticles to the liquid can significantly increase the thermal conductivity of the fluid [1]. This study investigates the thermal conductivity of diamond nanofluid. The nanofluid is HPLC grade water with 1% by volume diamond nanoparticles that are 5-50 nm in diameter. The thermal conductivity was measured by the transient hot-wire method. In order to verify the experimental measurement, the thermal conductivity of pure water (HPLC grade) was conducted and the measurement error is 3.6%. The experimental results show that the diamond nanoparticles can enhance the thermal conductivity of nanofluid. At an ambient temperature of 21 °C, the thermal conductivity for nanofluid was determined to be 1.00 W/m-K comparing with the thermal conductivity of 0.60 W/m-K for pure water (HPLC grade). Therefore, the nanofluid provides a significant increase in thermal conductivity. Utilizing this nanofluid, an oscillating Heat pipe was developed and tested. Experimental results showed that when the oscillating Heat pipe is charged with diamond nanofluids, the increase in Heat Transport Capability can be significant and highly dependent on the operating temperatures.Copyright © 2006 by ASME