Heat Transfer Enhancement of Horizontal Oscillating Heat Pipes With Micro-/Nanostructured Surface

2020 ◽  
Vol 142 (7) ◽  
Author(s):  
Tingting Hao ◽  
Huiwen Yu ◽  
Xuehu Ma ◽  
Zhong Lan
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Performance ◽  
Capillary Flow ◽  
Pure Water ◽  
Heat Pipes ◽  
Contact Angles ◽  
Horizontal Direction ◽  
Working Fluid ◽  
Transfer Performance ◽  
Nanostructured Surface

Abstract For oscillating heat pipes (OHPs) with low turn number (<9) positioned in the horizontal direction, the working fluid could not easily flow back to the evaporator due to the absence of gravity. Based on this, copper OHP with superhydrophilic micro-/nanostructured surface was investigated to enhance the heat transfer performance by introducing additional capillary force. OHPs with six turns were fabricated with bare copper and micro-/nanostructured inner surfaces for comparison. Pure water was used as the working fluid. Contact angles of water on the copper and superhydrophilic surfaces were 36.7 and 0 deg, respectively. The filling ratios of water were 50%, 65%, and 80%, respectively. Thermal resistance and liquid slug oscillations of OHPs were investigated at the heat input ranging from 100 to 380 W. Experimental results showed that OHPs with the superhydrophilic micro-/nanostructured surface showed an enhanced heat transfer performance due to the micro-/nanostructure-induced capillary flow in the horizontal direction. The optimum filling ratio was 65% in this work. The superhydrophilic micro-/nanostructured surface could significantly facilitate the backflow of the working fluid to the evaporator section and accelerate oscillating motions of liquid slugs. With the increasing of 0–70% in slug oscillating amplitude and 0–100% in slug oscillating velocity, micro-/nanostructured OHPs improved the heat transfer performance by up to 10% compared with the copper OHPs due to the wicking effect.

An Investigation of Flat-Plate Oscillating Heat Pipes

2010 ◽  
Author(s):  
Peng Cheng ◽  
Scott Thompson ◽  
Joe Boswell ◽  
Hongbin Ma
Keyword(s):  
Heat Transfer ◽  
Thermal Resistance ◽  
Flat Plate ◽  
Heat Transfer Performance ◽  
Operating Temperature ◽  
Pure Water ◽  
Heat Pipes ◽  
Copper Plate ◽  
Working Fluid ◽  
Transfer Performance

The heat transfer performance of flat-plate oscillating heat pipes (FP-OHPs) was investigated experimentally and theoretically. Two layers of channels were created by machining grooves on both sides of copper plate, in order to increase the channel number per unit volume. The channels had rectangular cross-sections with hydraulic diameters ranging from 0.762 mm to 1.389 mm. Acetone, water and diamond/acetone, gold/water and diamond/water nanofluids were tested as working fluids. It was found that the FP-OHP’s thermal resistance depended on the power input and operating temperature. The FP-OHP charged with pure water achieved a thermal resistance of 0.078°C/W while removing 560 W with a heat flux of 86.8 W/cm2. The thermal resistance was further decreased when nanofluid was used as the working fluid. A mathematical model predicting the heat transfer performance was developed to predict the effects of channel dimension, heating mode, working fluid and operating temperature on the thermal performance of the FP-OHP. Results presented here will assist in optimization of the FP-OHP and provide a better understanding of heat transfer mechanisms occurring in an OHPs.

EXPERIMENTAL STUDY ON THERMAL TRANSPORT PHENOMENON OF NANOFLUIDS AS WORKING FLUID IN HEAT EXCHANGER

2014 ◽  
Vol 22 (01) ◽  
pp. 1450005 ◽  
Author(s):  
SHUICHI TORII
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Transfer Performance ◽  
Pure Water ◽  
Horizontal Tube ◽  
Constant Heat Flux ◽  
Working Fluid ◽  
Transfer Performance ◽  
Nanoparticles Concentration ◽  
Transfer Behavior

This paper aims to study the convective heat transfer behavior of aqueous suspensions of nanoparticles flowing through a horizontal tube heated under constant heat flux condition. Consideration is given to the effects of particle concentration and Reynolds number on heat transfer enhancement and the possibility of nanofluids as the working fluid in various heat exchangers. It is found that (i) significant enhancement of heat transfer performance due to suspension of nanoparticles in the circular tube flow is observed in comparison with pure water as the working fluid, (ii) enhancement is intensified with an increase in the Reynolds number and the nanoparticles concentration, and (iii) substantial amplification of heat transfer performance is not attributed purely to the enhancement of thermal conductivity due to suspension of nanoparticles.

scholarly journals Augmentation of the Heat Transfer Performance of a Sinusoidal Corrugated Enclosure by Employing Hybrid Nanofluid

2014 ◽  
Vol 6 ◽  
pp. 147059 ◽  
Author(s):  
Behrouz Takabi ◽  
Saeed Salehi
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Performance ◽  
Heated Surface ◽  
Pure Water ◽  
Maximum Error ◽  
Temperature Fields ◽  
Working Fluid ◽  
Hybrid Nanofluid ◽  
Transfer Performance ◽  
Lower Temperature

This paper numerically examines laminar natural convection in a sinusoidal corrugated enclosure with a discrete heat source on the bottom wall, filled by pure water, Al2O3/water nanofluid, and Al2O3-Cu/water hybrid nanofluid which is a new advanced nanofluid with two kinds of nanoparticle materials. The effects of Rayleigh number (103≤Ra≤106) and water, nanofluid, and hybrid nanofluid (in volume concentration of 0% ≤ ϕ ≤ 2%) as the working fluid on temperature fields and heat transfer performance of the enclosure are investigated. The finite volume discretization method is employed to solve the set of governing equations. The results indicate that for all Rayleigh numbers been studied, employing hybrid nanofluid improves the heat transfer rate compared to nanofluid and water, which results in a better cooling performance of the enclosure and lower temperature of the heated surface. The rate of this enhancement is considerably more at higher values of Ra and volume concentrations. Furthermore, by applying the modeling results, two correlations are developed to estimate the average Nusselt number. The results reveal that the modeling data are in very good agreement with the predicted data. The maximum error for nanofluid and hybrid nanofluid was around 11% and 12%, respectively.

Heat Transfer Performance of Microgroove Back Plate Heat Pipes with Working Fluid and Heating Power

2020 ◽  
Vol 29 (4) ◽  
pp. 982-991
Author(s):  
Yanpeng Wu ◽  
Jie Jia ◽  
Dongmin Tian ◽  
Yew Khoy Chuah
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Performance ◽  
Heat Pipes ◽  
Heating Power ◽  
Working Fluid ◽  
Transfer Performance ◽  
Plate Heat ◽  
Back Plate

Experimental Investigation of Oscillating Heat Pipe With Hybrid Fluids of Liquid Metal and Water

2019 ◽  
Vol 141 (7) ◽  
Author(s):  
Tingting Hao ◽  
Hongbin Ma ◽  
Xuehu Ma
Keyword(s):  
Heat Transfer ◽  
Liquid Metal ◽  
Heat Pipe ◽  
Heat Input ◽  
Heat Transfer Performance ◽  
Pure Water ◽  
Experimental Results ◽  
Working Fluid ◽  
Transfer Performance ◽  
Oscillating Heat Pipe

A new oscillating heat pipe (OHP) charged with hybrid fluids can improve thermal performance. The key difference in this OHP is that it uses room temperature liquid metal (Galinstan consisting of gallium, indium, and tin) and water as the working fluid. The OHP was fabricated on a copper plate with six turns and a 3 × 3 mm2 cross section. The OHP with hybrid fluids as the working fluid was investigated through visual observation and thermal measurement. Liquid metal was successfully driven to flow through the OHP by the pressure difference between the evaporator and the condenser without external force. Experimental results show that while added liquid metal can increase the heat transport capability, liquid metal oscillation amplitude decreases as the filling ratio of liquid metal increases. Visualization of experimental results show that liquid metal oscillation position and velocity increase as the heat input increases. Oscillating motion of liquid metal in the OHP significantly increases the heat transfer performance at high heat input. The lowest thermal resistance of 0.076 °C/W was achieved in the hybrid fluids-filled OHP with a heat input of 420 W. We experimentally demonstrated a 13% higher heat transfer performance using liquid metal as the working fluid compared to an OHP charged with pure water.

Heat Transfer Characteristic of Flat Trapezoid Grooved Micro Heat Pipes

2014 ◽  
Vol 609-610 ◽  
pp. 1526-1531 ◽  
Author(s):  
Yan Xia Yang ◽  
Xiao Dong Wang ◽  
Yi Luo ◽  
Liang Liang Zou
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Heat Transfer Performance ◽  
Capillary Flow ◽  
Transfer Characteristic ◽  
Fluid Distribution ◽  
Working Fluid ◽  
Transfer Performance ◽  
Maximum Heat ◽  
Micro Heat Pipe

To study the heat transfer performance of micro heat pipe, theoretical analysis of flat plate micro heat pipe with trapezoid cross section are presented in this paper. A one-dimensional stationary mathematical model for micro heat pipe grooved capillary flow using finite volume method (FVM) was established. The micro heat pipe had vapor space connect with each other and the influences of shear stress between vapor and fluid in the working process were described in the model which made the model more precisely. The axial variation of working fluid distribution in the heat pipe, pressure difference between vapor and liquid, and velocity of vapor and liquid were analyzed. In addition, the maximum heat transport capacity of micro heat pipe was calculated. The simulation results showed good agreement with the experiment results, and it could predict the heat transfer performance accurately, which was useful to micro heat pipe structural design.

An Investigation of Flat-Plate Oscillating Heat Pipes

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Peng Cheng ◽  
Scott Thompson ◽  
Joe Boswell ◽  
H. B. Ma
Keyword(s):  
Heat Transfer ◽  
Thermal Resistance ◽  
Flat Plate ◽  
Cross Sections ◽  
Heat Transfer Performance ◽  
Heat Pipes ◽  
Power Input ◽  
Copper Plate ◽  
Working Fluid ◽  
Transfer Performance

The heat transfer performance of flat-plate oscillating heat pipes (FP-OHPs) was investigated experimentally and theoretically. Two layers of channels were created by machining grooves on both sides of a copper plate in order to increase the channel number per unit volume. The channels had rectangular cross-sections with hydraulic diameters ranging from 0.762 mm to 1.389 mm. Acetone, water, diamond/acetone, gold/water, and diamond/water nanofluids were tested as working fluids. It was found that the FP-OHP’s thermal resistance depended on the power input and operating temperature. The FP-OHP charged with 0.0003 vol % gold/water nanofluids achieved a thermal resistance of 0.078 K/W while removing 560 W with a heat flux of 86.8 W/cm2. The thermal resistance was further decreased when the nanofluid was used as the working fluid. A mathematical model predicting the heat transfer performance was developed to predict the thermal performance of the FP-OHP. Results presented here will assist in the optimization of the FP-OHP and provide a better understanding of heat transfer mechanisms occurring in OHPs.

Heat Transfer Augmentation of Aqueous Suspensions of Nanodiamonds in Turbulent Pipe Flow

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
Shuichi Torii ◽  
Wen-Jei Yang
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Transfer Performance ◽  
Pure Water ◽  
Horizontal Tube ◽  
Constant Heat Flux ◽  
Turbulent Pipe Flow ◽  
Working Fluid ◽  
Transfer Performance ◽  
Aqueous Suspensions

This paper aims to study the convective heat transfer behavior of aqueous suspensions of nanodiamond particles flowing through a horizontal tube heated under a constant heat flux condition. Consideration is given to the effects of particle concentration and Reynolds number on heat transfer enhancement. It is found that (i) significant enhancement of heat transfer performance due to suspension of nanodiamond particles in the circular tube flow is observed in comparison with pure water as the working fluid, (ii) the enhancement is intensified with an increase in the Reynolds number and the nanodiamond concentration, and (iii) substantial amplification of heat transfer performance is not attributed purely to the enhancement of thermal conductivity due to suspension of nanodiamond particles.

scholarly journals CPU COOLING OF DESKTOP COMPUTER BY PARALLEL MINIATURE HEAT PIPES

1970 ◽  
Vol 40 (2) ◽  
pp. 104-109 ◽  
Author(s):  
Chowdhury Md. Feroz ◽  
Ahmed Imtiaz Uddin
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Performance ◽  
Heat Pipes ◽  
Working Fluid ◽  
Transfer Performance ◽  
Copper Block ◽  
Desktop Computer ◽  
Condenser Section ◽  
Working Fluids ◽  
Conventional Cooling

Heat transfer performance of parallel miniature heat pipes (MHPs) of 2.8 mm ID used for cooling desktop computer with different working fluids is presented in this paper. In cooling desktop processors, MHPs consists of six single tube heat pipes connected by a copper block at the evaporator section and fifteen parallel copper sheets used as external fins at the condenser section. Acetone and ethanol are used as working fluid. The copper block is placed above the heat source (on the top of the processor) and the condenser section is provided with external fins perpendicular to the MHPs. Heat transfer characteristics of MHPs using different working fluids are determined experimentally, based on the principle of phase. The experimental results show that, the maximum and steady state temperature of the processor has been reduced significantly by using MHPs with acetone as working fluid instead of conventional cooling fan. Additional use of a fan at the condenser section results much lower processor surface temperature for both working fluids. Key words: CPU cooling; Desktop processor; Heat transfer performance; Miniature Heat Pipe; Working fluid.DOI: 10.3329/jme.v40i2.5351Journal of Mechanical Engineering, Vol. ME 40, No. 2, December 2009 104-109

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