scholarly journals Sodium-Potassium Alloy Heat Pipe under Geyser Boiling Experimental Study: Heat Transfer Analysis

Energies ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7582
Author(s):  
Hongzhe Zhang ◽  
Fang Ye ◽  
Hang Guo ◽  
Xiaoke Yan
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Heating Power ◽  
Heat Transfer Analysis ◽  
Working Fluid ◽  
Condenser Section ◽  
Sodium Potassium ◽  
Alloy Heat ◽  
Convection Cooling ◽  
Boiling Mode

In the geyser boiling mode, the working fluid state is divided into a boiling process and a quiet process, and the sodium-potassium (Na-K) alloy heat pipe can discontinuously transfer heat at each boiling. The overheating of the liquid working fluid at the bottom causes short-term boiling and forms slug bubble, the strong condensing ability quickly conducts heat from the evaporator section. And geyser boiling can occur before the working fluid forms continuous flow, so it transfers more heat at lower temperatures than natural convection cooling. In this study, the heat transfer process of a Na-K alloy heat pipe with forced convection cooling under different heating power was experimental studied. The geyser boiling mode can make the Na-K alloy heat pipe work below 650 °C and reduce the start-up time. In the process of geyser boiling, the heat transfer quantity was increased by the boiling frequency and the amount of vapor produced in a single boiling. The boiling temperature had no obvious change with the increased of heating power, and the condenser section temperature increased with the heating power.

Effect of Tube Bending on Heat Transfer Characteristics of Miniature Heat Pipe with Sintered Porous Media

2011 ◽  
Vol 312-315 ◽  
pp. 1015-1020 ◽  
Author(s):  
P. Sakulchangsatjatai ◽  
N. Thuchayapong ◽  
P. Terdtoon ◽  
N. Sangsirakoup
Keyword(s):  
Heat Transfer ◽  
Porous Media ◽  
Heat Pipe ◽  
Working Fluid ◽  
Tube Bending ◽  
Heat Transfer Characteristics ◽  
Small Space ◽  
Condenser Section ◽  
Transfer Characteristics ◽  
Evaporator Section

Miniature heat pipe is a compact heat transfer device with very high heat transfer capability. The miniature heat pipes have been widely accepted for thermal management in laptop computer. Generating heat from chip-set is rapidly transferred to a heat sink via the miniature heat pipe which occupies small space, resulting in smaller and more attractive size of the laptop. Heat pipe bending is unavoidable in such small space. However, tube bending decreases thermal performance of heat pipe and it stops working in some cases. In this study, a computer program to simulate heat transfer characteristics of a bending water-copper-sintered-wick heat pipe has been established. Domains of heat pipe consist of three parts; vapor of working fluid in vapor core which transfer heat and mass from evaporator section to condenser section, liquid of working fluid in wick which transfer heat and mass from condenser section to evaporator section in porous media by capillary force, and container wall. In simulation, fluid flow and heat transfer were assumed to be steady, laminar and incompressible. The porous media is saturated with liquid and working fluid is assumed to be Newtonian fluid. The governing equations, i.e. continuity, Navier-Stokes, and energy equations, and boundary conditions were solved by using the Finite Element Method (FEM). Several bending angles (0 and 90; angle measured from straight pipe) with 6 mm outer diameter and 200 mm length were simulated and tested. It was found that the predicted and experimental thermal resistances of heat pipe, when bending angle increases from 0 to 90, increased from 0.47°C/W to 0.65°C/W and 0.67°C/W to 0.88°C/W respectively, due to rising of the vapor pressure drop in vapor channel. The simulation results are in agreement with experimental data with 26-29% error.

scholarly journals Heat transfer analysis of looped micro heat pipes with graphene oxide Nanofluid for Li-ion battery

2020 ◽  
pp. 218-218
Author(s):  
Prabu Manikanda ◽  
G. Sureshkannan ◽  
S. Suresh ◽  
Kumar Senthil
Keyword(s):  
Heat Transfer ◽  
Graphene Oxide ◽  
Heat Pipe ◽  
Heat Transfer Analysis ◽  
New Combination ◽  
Working Fluid ◽  
Li Ion Batteries ◽  
Li Ion Battery ◽  
Micro Heat Pipe ◽  
Li Ion

Li-ion batteries play a vital role in electromechanical devices. The heat load on such batteries varies with time and application which falls as high-temperature rise and it causes severe damages on a device and reduces the life cycle. It will be a big challenge in future decades of electronic devices and the electric car revolution. To overcome such difficulties, this work is considered for thermal management of small Li-ion batteries to check the possibilities through the micro heat pipe. Due to the high impact of Nanotechnology in heat transfer science, Acetone, De-ionized water, and Tetrahydrofuran fluids are blended with Graphene Oxide Nanoparticles to prepare the Nanofluids by ultrasonic method. Here, Tetrahydrofuran is a new combination of Nano-working fluid and not addressed by pre-researchers. Tetrahydrofuran-graphene Nanofluid provides 61% of improved thermal conductivity than the other two fluids which accelerates the heat transfer rate with reduced thermal resistance in the range of 0.09- 0.640C/W. To validate the experimental results, a real-time study has been done on Li-ion batteries for a day and ensured the reduction of overheat issues. Hence, the present work will support the Li-ion battery to work in an optimal temperature range in a new way of micro heat pipe with Nanofluid.

Developing the Coaxial Dual-Pipe Heat Pipe for Applications on Heat Pipe Cooler

2011 ◽  
Vol 133 (9) ◽  
Author(s):  
Chen-Ching Ting ◽  
Chien-Chih Chen
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Cooling Water ◽  
Working Fluid ◽  
Observation Window ◽  
Condenser Section ◽  
Transfer Property ◽  
Heat Transfer Property ◽  
Adiabatic Section ◽  
Pipe Heat

This article presents significant experimental data about the coaxial dual-pipe heat pipe which is invented by our CCT laboratory. The coaxial dual-pipe heat pipe is built-in an inner pipe in the adiabatic section of a common heat pipe. A common heat pipe is composed of three sections: the evaporator section at the one end; the condenser section at the other end; and the adiabatic section in between. The vapor and the liquid phases of the working fluid flow in opposite directions through the core and the wick, respectively. This special heat transfer behavior causes a common heat pipe to yield the discrete heat transfer property. In process, the vapor directly brings large amounts of heat from heat source and rapidly flows through the adiabatic section to the condenser section. This intelligent heat transfer technique lets the heat pipe yield extremely large thermal conductivity. Unfortunately, a heat pipe integrated with cooling fin in the adiabatic section has changed its original heat transfer property. The integrated cooling fin in the adiabatic section has in advance taken heat of the vapor away and caused the vapor to be condensed in the adiabatic section. Therefore, the vapor cannot reach the condenser section and the condenser section hence loses its cooling capability. In other words, the effective cooling length of a common heat pipe which is integrated with cooling fin in the adiabatic section is shortened. The coaxial dual-pipe heat pipe is built-in an inner pipe in the adiabatic section of a common heat pipe to avoid heat of the vapor to be earlier taken away and even condensed in the adiabatic section. Experimental study in this work first built a home-made square coaxial dual-pipe heat pipe integrated with outside isothermal cycling cooling water as the coaxial dual-pipe heat pipe cooler. The home-made square coaxial dual-pipe heat pipe has an observation window. It is convenient to observe change of the two-phase flow inside the heat pipe influenced by the outside cooling water. The results show that the new developed coaxial dual-pipe heat pipe cooler has kept the original heat transfer property of the bare heat pipe. The vapor has reached the condenser section.

Heat Transport Limitation of a Triangular Micro Heat Pipe

2003 ◽  
Author(s):  
D. Sugumar ◽  
Kek Kiong Tio
Keyword(s):  
Heat Pipe ◽  
Heat Transport ◽  
Operating Temperature ◽  
Working Fluid ◽  
Transport Capacity ◽  
Condenser Section ◽  
Micro Heat Pipe ◽  
Evaporator Section ◽  
Higher Temperature ◽  
Specific Temperature

A micro heat pipe will operate effectively by achieving its maximum possible heat transport capacity only if it is to operate at a specific temperature, i.e., design temperature. In reality, micro heat pipe’s may be required to operate at temperatures different from the design temperature. In this study, the heat transport capacity of an equilateral triangle micro heat pipe is investigated. The micro heat pipe is filled optimally with working fluid for a specific design temperature and operated at different operating temperatures. For this purpose, water, pentane and acetone was selected as the working fluids. From the numerical results obtained, it shows that the optimal charge level of the micro heat pipe is dependent on the operating temperature. Furthermore, the results also shows that if the micro heat pipe is to be operated at temperatures other than its design temperature, its heat transport capacity is limited by the occurrence of flooding at the condenser section or dryout at the evaporator section, depending on the operating temperature and type of working fluid. It is observed that when the micro heat pipe is operated at a higher temperature than its design temperature, the heat transport capacity increases but limited by the onset of dryout at the evaporator section. However, the heat transport capacity decreases if it is to be operated at lower temperatures than its design temperature due to the occurrence of flooding at condenser end. From the results obtained, we can conclude that the performance of a micro heat pipe is decreased if it is to be operated at temperatures other than its design temperature.

scholarly journals Thermal Characteristics Analysis on Multi- Heat Pipe Induced Heat Exchanger

2019 ◽  
Vol 9 (2S2) ◽  
pp. 143-147 ◽  
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Pipe ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Cold Water ◽  
Hot Water ◽  
Working Fluid ◽  
Physical Parameters

In this investigation of multi heat pipe induced in heat exchanger shows the developments in heat transfer is to improve the efficiency of heat exchangers. Water is used as a heat transfer fluid and acetone is used as a working fluid. Rotameter is set to measure the flow rate of cold water and hot water. To maintain the parameter as experimental setup. Then set the mass flow rate of hot water as 40 LPH, 60LPH, 80 LPH, 100LPH, 120 LPH and mass flow rate of cold water as 20 LPH, 30 LPH, 40 LPH, 50 LPH, and 60 LPH. Then 40 C, 45 ºC, 50 ºC, 55 C, 60 ºC are the temperatures of hot water at inlet are maintained. To find some various physical parameters of Qc , hc , Re ,, Pr , Rth. The maximum effectiveness of the investigation obtained from condition of Thi 60 C, Tci 32 C and 100 LPH mhi, 60 LPH mci the maximum effectiveness attained as 57.25. Then the mhi as 100 LPH, mci as 60 LPH and Thi at 40 C as 37.6%. It shows the effectiveness get increased about 34.3 to the maximum conditions.

scholarly journals The effect of operating parameters on the heat transfer in the heat pipe

2021 ◽  
Vol 2119 (1) ◽  
pp. 012088
Author(s):  
A. A. Litvintceva ◽  
N. I. Volkov ◽  
N. I. Vorogushina ◽  
V. A. Moskovskikh ◽  
V. V. Cheverda
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Pipe ◽  
Temperature Difference ◽  
Heat Pipes ◽  
Working Fluid ◽  
Operating Parameters ◽  
Temperature Stabilization ◽  
Ir Camera ◽  
Fluid Properties

Abstract Heat pipes are a good solution for temperature stabilization, for example, of microelectronics, because these kinds of systems are without any moving parts. Experimental research of the effect of operating parameters on the heat transfer in a cylindrical heat pipe has been conducted. The effect of the working fluid properties and the porous layer thickness on the heat flux and temperature difference in the heat pipe has been investigated. The temperature field of the heat pipe has been investigated using the IR-camera and K-type thermocouples. The data obtained by IR-camera and K-type thermocouples have been compared. It is demonstrated the power transferred from the evaporator to the condenser is a linear function of the temperature difference between them.

scholarly journals An investigation on effect of EDL on heat transfer of micro heat pipe with square and triangular cross section

2020 ◽  
Vol 21 (3) ◽  
pp. 309
Author(s):  
Maryam Fallah Abbasi ◽  
Hossein Shokouhmand ◽  
Morteza Khayat
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Double Layer ◽  
Electric Double Layer ◽  
Heat Pipes ◽  
The Body ◽  
Working Fluid ◽  
Two Phase ◽  
Micro Heat Pipe ◽  
Micro Heat Pipes

Electronic industries have always been trying to improve the efficiency of electronic devices with small dimensions through thermal management of this equipment, thus increasing the use of small thermal sinks. In this study micro heat pipes with triangular and square cross sections have been manufactured and tested. One of the main objectives is to obtain an understanding of micro heat pipes and their role in energy transmission with electrical double layer (EDL). Micro heat pipes are highly efficient heat transfer devices, which use the continuous evaporation/condensation of a suitable working fluid for two-phase heat transport in a closed system. Since the latent heat of vaporization is very large, heat pipes transport heat at small temperature difference, with high rates. Because of variety of advantage features these devices have found a number of applications both in space and terrestrial technologies. The theory of operation micro heat pipes with EDL is described and the micro heat pipe has been studied. The temperature distribution have achieved through five thermocouples installed on the body. Water and different solution mixture of water and ethanol have used to investigate effect of the electric double layer heat transfer. It was noticed that the electric double layer of ionized fluid has caused reduction of heat transfer.

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