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.

Experimental Study on Oscillating Heat Pipe With Hydraulic Diameter Far Exceeding the Maximum Hydraulic Diameter

2019 ◽  
Author(s):  
Lilin Chu ◽  
Yulong Ji ◽  
Chunrong Yu ◽  
Yantao Li ◽  
Hongbin Ma ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Heat Transfer Performance ◽  
Hydraulic Diameter ◽  
Working Fluid ◽  
Transfer Performance ◽  
Vertical Orientation ◽  
Oscillating Heat Pipe ◽  
Horizontal Orientation ◽  
Small Bubbles

Abstract In order to understand the heat transfer performance, startup and fluid flow condition of oscillating heat pipe (OHP) with hydraulic diameter far exceeding the maximum hydraulic diameter (MHD), an experimental investigation on heat transfer performance and visualization was conducted. From the experimental performance, it is found that the OHP can still work well with ethanol as the working fluid when the tube diameter has exceeded the MHD of 91.6%. In addition, the detailed flow patterns of the OHP were recorded by a highspeed camera for vertical and horizontal orientation to understand its physical mechanism. In the vertical orientation, initially working fluid generates small bubbles, and then the small bubbles coalesce and grow to vapor plugs, the vapor plugs finally pushes the liquid slugs to oscillate in the tube. In the horizontal orientation, the working fluid surface fluctuates due to the vapors flow from the evaporator to the condenser and bubbles burst in the evaporator. When the peak of liquid wave reaches the upper surface of tube, a liquid slug has been formed, and then the steam flow pushes the liquid slugs to oscillate in the tube.

Experimental Study on Oscillating Heat Pipe With a Hydraulic Diameter Far Exceeding the Maximum Hydraulic Diameter

2020 ◽  
Vol 12 (6) ◽  
Author(s):  
Lilin Chu ◽  
Yulong Ji ◽  
Hongbin Ma ◽  
Yantao Li ◽  
Chao Chang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Input ◽  
High Speed ◽  
Heat Transfer Performance ◽  
Power Input ◽  
Hydraulic Diameter ◽  
Working Fluid ◽  
Transfer Performance ◽  
Vertical Orientation ◽  
Oscillating Heat Pipe

Abstract In order to understand the heat transfer performance, startup, and fluid flow conditions of oscillating heat pipes (OHPs) with a hydraulic diameter far exceeding the maximum hydraulic diameter (MHD) defined by dh,max≤2σBo/(ρl−ρv)g, an experimental investigation on the OHP heat transfer performance and visualization was conducted. The effects of heat input, working fluid, and orientation on the oscillating motion and heat transfer performance of the investigated OHPs have been conducted. In addition, the detailed flow patterns of the tested OHPs were recorded by a high-speed camera from both vertical and horizontal orientations. Results show that the maximum hydraulic diameter, which can form a train of liquid plugs and vapor bubbles, which is essential for an OHP to function, depends on the heat input, working fluid, and orientation. At a power input of 1000 W, the OHP can still function well even when the tube diameter exceeds the MHD of 91.6%. This maximum hydraulic dimeter depends on the orientation. While the OHP with a dimeter far exceeding the MHD can still function, the heat transfer performance of the OHP in a vertical orientation is better than in a horizontal orientation.

An Experimental Investigation of the Heat Transfer Performance of an Oscillating Heat Pipe With Copper Oxide (CuO) Microstructure Layer on the Inner Surface

2013 ◽  
Vol 135 (7) ◽  
Author(s):  
Yulong Ji ◽  
Chen Xu ◽  
Hongbin Ma ◽  
Pan Xinxiang
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Copper Oxide ◽  
Heat Pipe ◽  
Heat Transfer Performance ◽  
Working Fluid ◽  
Transfer Performance ◽  
Oscillating Heat Pipe ◽  
Inner Surface ◽  
Copper Tubing

This paper presents an experimental investigation of whether heat transfer performance in an oscillating heat pipe (OHP) would improve if the inner surface of the heat pipe was coated with a layer of copper oxide (CuO). The OHP had six turns and three sections, i.e., evaporator, condenser, and adiabatic section with lengths of 40 mm, 64 mm, and 51 mm, respectively. The cleaned copper tubing was chemically treated with a chemical solution and heated in a furnace. A microstructure layer of CuO was formed in the inner surface of the OHP with K2S2O8 and KOH. The working fluid in this study was water with filling ratios ranging from 40% to 70%. The experimental results show that the CuO microstructure layer is superhydrophilic and can enhance the OHP heat transfer performance. The investigation results in a new way to enhance the heat transfer performance of an OHP.

Heat Transfer Characteristics of Oscillating Heat Pipe With Water and Ethanol as Working Fluids

2010 ◽  
Vol 132 (12) ◽  
Author(s):  
Haizhen Xian ◽  
Yongping Yang ◽  
Dengying Liu ◽  
Xiaoze Du
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Inclination Angle ◽  
Heat Transfer Performance ◽  
Filling Ratio ◽  
Working Fluid ◽  
Transfer Performance ◽  
Heat Transfer Characteristics ◽  
Oscillating Heat Pipe ◽  
Transfer Characteristics

In this paper, experiments were conducted to achieve a better understanding of the oscillating heat pipe (OHP) operating behavior with water and ethanol as working fluid. The experimental results showed that there existed a necessary temperature difference between the evaporator and the condenser section to keep the heat pipe working. The maximum effective conductivity of the water OHP reached up to 259 kW/m K, while that of the ethanol OHP is of 111 kW/m K. Not all the OHPs are operated in the horizontal operation mode. The heat transfer performance of the ethanol OHP was obviously affected by the filling ratio and the inclination angle but the influence law is irregular. The effect of the filling ratio and the inclination angle of the water OHP were smaller than that of the ethanol one. The heat transfer performance of the OHP was improved with increase of operating temperature. The startup characteristics of the OHP depended on the establishment of the integral oscillating process, which was determined by the operating factors. The startup temperature of the ethanol OHP varied from 40°C to 50°C and that of the water, OHP varied from 40°C to 60°C without considering the horizontal operating mode. The water OHP showed a better performance and more stable heat transfer characteristics than the ethanol OHP, which had no obvious advantages of the startup capability as well.

Copper Oxide (CuO) Effect on Heat Transfer Performance in an Oscillating Heat Pipe

2012 ◽  
Author(s):  
Yulong Ji ◽  
Chen Xu ◽  
Hongbin Ma
Keyword(s):  
Heat Transfer ◽  
Copper Oxide ◽  
Heat Pipe ◽  
Heat Transfer Performance ◽  
Working Fluid ◽  
Transfer Performance ◽  
Oscillating Heat Pipe ◽  
Inner Surface ◽  
Copper Tubing ◽  
Adiabatic Section

An experimental investigation of an oscillating heat pipe (OHP) with an inner surface coated with a copper oxide (CuO) layer was conducted. The OHP has six turns and three sections: evaporator, condenser and adiabatic section with the lengths of 40 mm, 64 mm and 51 mm, respectively. The cleaned copper tubing was chemically treated with a chemical solution and heated in a furnace. A layer of CuO was formed in the inner surface of the OHP. A working fluid (water in this study) at filling ratios ranging from 40% to 70% was studied. The experimental results show that the CuO layer can enhance the heat transfer performance of the OHP. The investigation results in a new way to enhance the heat transfer performance of an OHP.

Experimental Investigation of a Three-Phase Oscillating Heat Pipe

2019 ◽  
Vol 11 (6) ◽  
Author(s):  
Tingting Hao ◽  
Hongbin Ma ◽  
Xuehu Ma
Keyword(s):  
Heat Transfer ◽  
Liquid Phase ◽  
Heat Pipe ◽  
Thermal Performance ◽  
Heat Transfer Performance ◽  
Solid Phase ◽  
Working Fluid ◽  
Transfer Performance ◽  
Oscillating Heat Pipe ◽  
Three Phase

This paper presents an investigation of a three-phase oscillating heat pipe (3P OHP). The working fluid in the OHP consists of phase change material (PCM) and water. During the operation, the PCM changes the phase between solid and liquid, and water changes phase between liquid and vapor. The OHP investigated herein contains three phases: solid, liquid, and vapor. Erythritol was selected as the PCM with an instant cooling effect when dissolved in water due to the high fusion heat of 340 J/g. When the working fluid flows into the evaporator section, the PCM solid phase of the working fluid can become liquid phase in the evaporator, and the PCM liquid phase of the working fluid become solid phase in the condenser. The effects of heat input ranging from 100 to 420 W, and the erythritol concentration ranging from 1 to 50 wt % on the slug oscillations, and the OHP thermal performance was investigated. Experimental results show that while the erythritol can help to increase the heat transfer performance of an OHP, the heat transfer performance depends on the erythritol concentration. With a range of 1–5 wt % concentration of erythritol/water mixtures, a maximum 10% increase in the thermal performance was observed. When the erythritol concentration of erythritol/water mixtures was increased to a range of 10–50 wt %, the thermal performance of OHPs was lower than pure water-filled OHP, and the thermal performance decreased as the erythritol concentration was further increased. In addition, visualization results showed that slug oscillation amplitudes and velocities were reduced in the OHPs with erythritol solution compared with water-filled OHP.

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.

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