scholarly journals Experimental investigation and CFD analysis of a air cooled condenser heat pipe

2011 ◽  
Vol 15 (3) ◽  
pp. 759-772 ◽  
Author(s):  
Selvan Annamalai ◽  
Velraj Ramalingam
Keyword(s):  
Experimental Investigation ◽  
Steady State ◽  
Heat Pipe ◽  
Input Power ◽  
Outer Diameter ◽  
Cfd Analysis ◽  
Condenser Section ◽  
Transient Conditions ◽  
Evaporator Section

In the present work a heat pipe of one meter length and 0.031m outer diameter was constructed and the experiments are conducted to determine the surface and vapour temperature at steady and transient conditions for two different input power in the evaporator section and cooling the condenser section by air. A CFD analysis was also carried and the results under steady state conditions are compared with the results obtained from the experiments and reported in this paper.

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 Experimental Investigation of the Thermal Performance of a Wickless Heat Pipe Operating with Different Fluids: Water, Ethanol, and SES36. Analysis of Influences of Instability Processes at Working Operation Parameters

Energies ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 80 ◽  
Author(s):  
Rafal Andrzejczyk
Keyword(s):  
Heat Pipe ◽  
Input Power ◽  
Liquid Pool ◽  
Filling Ratio ◽  
Working Fluid ◽  
Operating Pressure ◽  
Two Phase ◽  
Condenser Section ◽  
Transfer Resistance ◽  
Working Fluids

In this study, the influences of different parameters on performance of a wickless heat pipe have been presented. Experiments have been carried out for an input power range from 50 W to 300 W, constant cooling water mass flow rate of 0.01 kg/s, and constant temperature at the inlet to condenser of 10 °C. Three working fluids have been tested: water, ethanol, and SES36 (1,1,1,3,3-Pentafluorobutane) with different filling ratios (0.32, 0.51, 1.0). The wall temperature in different locations (evaporation section, adiabatic section, and condenser section), as well as operating pressure inside two phase closed thermosyphon have been monitored. The wickless heat pipe was made of 0.01 m diameter copper tube, which consists of an evaporator, adiabatic, and condensation sections with the same length (0.4 m). For all working fluids, a dynamic start-up effect caused by heat conduction towards the liquid pool was observed. Only the thermosyphon filled with SES36 was observed to have operation limitation caused by achieving the boiling limit in TPCTs (two-phase closed thermosyphons). The geyser boiling effect has been observed only for thermosyphon filled with ethanol and for a high filling ratio. The performance of the thermosyphon determined the form of the heat transfer resistance of the TPCT and it was found to be dependent of input power and filling ratio, as well as the type of working fluid and AR (aspect ratio). Comparison with other authors would seem to indicate that lower AR results in higher resistance; however, the ratio of condenser section length to inside diameter of pipe is also a very important parameter. Generally, performance of the presented thermosyphon is comparable to other constructions.

scholarly journals THERMAL PERFORMANCE ENHANCEMENT OF A VERTICAL THERMOSYPHON HEAT PIPE BY FLOW CONTROL OF THE TWO PHASES

2021 ◽  
Vol 25 (01) ◽  
pp. 109-122
Author(s):  
Alaa A. B. Temimy ◽  
◽  
Adnan A. Abdulrasool ◽  
Keyword(s):  
Heat Pipe ◽  
Thermal Performance ◽  
Performance Enhancement ◽  
Flow Patterns ◽  
Working Fluid ◽  
Three Dimensional Model ◽  
Complex Flow ◽  
Condenser Section ◽  
Evaporator Section ◽  
Two Phases

Heat Pipe (THP) has a continues evaporation/ condensation cycles of the working fluid. The flow patterns of the two phases is founds by previous published articles, as a non-steady complex spatial flow pattern. This type of the flow blocks the easy moving of the two-phases and limits the thermal performance of the THP. In this study, a copper tubes packing (TP) is simulated numerically to control/manage the flow streams of the two phases inside the THP. The simulated THP is 600mm length made of copper partially filled with water. The TP is consist of a two copper tubes attached contrary to each other with a neighboring openings. The upper tube (Riser tube) facilitate the moving of steam streams from evaporator section to the top of the condenser section. The lower tube (Down-comer tube) facilitate the moving of the condensate streams from the condenser section to the bottom of the evaporator section. The tested filling ratios are (40,50,55,60 and 70) % of evaporator section volume. The supplied heats are (50,75,100,150 and 200) W. The Computational Fluid Dynamics solution are done for a three dimensional model (3DCFD) using ANSYS/ Fluent R19.0 software. The simulation result of the steam volume fractions contours shows that the insertion of TP control the flow streams of both phases. Also prevent the formation of complex flow patterns then enhance the axial velocity vectors and reduce cross velocity vectors. The inserted TP provide a regular circulation paths for the working fluid phases and enhance evaporation /condensation processes. Hence it’s reduce the thermal resistance of the THP about 55% and enhance the thermal performance with the same percentage. In addition, the thermal performance of the enhanced TPTHP is not/a little influence due to the variation of the filling ratio.

Experimental Study of a Curved Rotating Heat Pipe

2008 ◽  
Vol 130 (10) ◽  
Author(s):  
T. A. Jankowski ◽  
F. C. Prenger ◽  
A. Razani
Keyword(s):  
Heat Pipe ◽  
Thermal Management ◽  
Working Fluid ◽  
Heat Sources ◽  
Refrigeration System ◽  
Condenser Section ◽  
Rotating Machine ◽  
Thermal Management System ◽  
Axis Of Rotation ◽  
Evaporator Section

A curved rotating heat pipe for use in motor and generator applications is studied experimentally. The heat pipe is built so that both the condenser and evaporator sections are parallel to the axis of rotation. The condenser section is close to the axis of rotation while the evaporator section can be placed in contact with off-axis heat sources in the rotating machine. The geometry is achieved by incorporating an S-shaped curve between the on-axis rotating condenser section and the off-axis revolving evaporator section. The curved rotating heat pipe allows for a direct coupling of the rotating condenser section to an on-axis stationary refrigeration system, while allowing the revolving evaporator section to intercept off-axis heat sources in the rotating machine. An experimental rotating heat pipe test apparatus was built and operated. The test data indicate that the working fluid continued to circulate, resulting in heat transfer with a high effective thermal conductivity, with the curved rotating heat pipe operating under the influence of centrifugal accelerations approaching 400g. Furthermore, the experimental results were used to validate a heat pipe thermal model that can be used in the design of rotating machines that rely on the curved rotating heat pipe as part of the thermal management system.

Effect of Filling Ratio on an Uneven Turn Oscillating Heat Pipe

2011 ◽  
Author(s):  
Aaron A. Hathaway ◽  
Hongbin Ma
Keyword(s):  
Experimental Investigation ◽  
Thermal Resistance ◽  
Flat Plate ◽  
Heat Pipe ◽  
Thermal Performance ◽  
Input Power ◽  
Filling Ratio ◽  
Inverted Position ◽  
Oscillating Heat Pipe ◽  
Test Conditions

An experimental investigation of the effect of filling ratio on the thermal performance for a flat plate oscillating heat pipe with uneven turns was conducted. The OHP was designed to have 14 long turns running from the evaporator to the condenser and 6 short turn occurring only in the evaporator. The factors varied for this experimental investigation were the input power, condensing temperature, and charging ratio. Experimental results show that for all test conditions, the OHP functioned very well and could operate with an input power of up to 1200 W and could reach a thermal resistance of 0.028 °C/W in the inverted position with a filling ratio of 70%.

Analysis of Heat Pipe Filled with Several Oxide Nanofluids on the Start-Up Process

2014 ◽  
Vol 490-491 ◽  
pp. 251-255 ◽  
Author(s):  
Yu Ying Gong ◽  
Zong Ming Liu ◽  
Wei Lin Zhao
Keyword(s):  
Temperature Distribution ◽  
Heat Pipe ◽  
Temperature Drop ◽  
Heat Pipes ◽  
Condenser Section ◽  
Evaporator Section ◽  
Heating Section ◽  
Start Up

Three heat pipes with nanofluids of Al2O3-water, CuO-water and SiO2-water were tested experimentally. The temperature distribution of their start-up process was analysed, and compared the heat pipe with water. The results showed that the start-up way of heat pipe filled with nanofluids was coincident, the heat pipe filled with nanofluids showed a lower start-up temperature and a shorter start-up time in evaporator section compared with heat pipe filled with water, the temperature drop between evaporator section and condenser section for the heat pipe filled with nanofluids were reduced by 2-5°C than that of the heat pipe filled with water. The effect of the length of the heating section of heat pipe filled with nanofluids on the start-up process was little.

Thermal Resistance of a Rotating Closed-Loop Pulsating Heat Pipe: Effect of Centrifugal Accelerations

2016 ◽  
Vol 851 ◽  
pp. 292-298
Author(s):  
Niti Kammuang-Lue ◽  
Deuansavanh Phommavongsa ◽  
Kritsada On-Ai ◽  
Phrut Sakulchangsatjatai ◽  
Pradit Terdtoon
Keyword(s):  
Thermal Resistance ◽  
Heat Pipe ◽  
Closed Loop ◽  
Working Fluid ◽  
Outer Side ◽  
Gravitational Acceleration ◽  
Pulsating Heat Pipe ◽  
Centrifugal Acceleration ◽  
Condenser Section ◽  
Evaporator Section

Objective of this study is to experimentally investigate the effect of centrifugal accelerations on thermal resistance of the rotating closed-loop pulsating heat pipe (RCLPHP). The RCLPHPs were made of a copper tube with internal diameter of 1.50 and 1.78 mm and bent into flower’s petal-shape and arranged into a circle with 11 turns. The evaporator section located at the outer end of the bundle while the condenser section placed around the center of the RCLPHP with no adiabatic section. Both sections had an identical length of 50 mm. R123, and ethanol was filled as working fluid respectively. The RCLPHP was installed on the test rig and it was rotated by the DC motor at the centrifugal acceleration of 0.5, 1, 3, 5, 10, and 20 times of the gravitational acceleration considering at the connection between the evaporator and condenser section. Heat input was generated by electrical annular-plate heaters and varied from 30 to 50, 100, 150, and 200 W. Ceramic papers, wooden plate, and insulation sheet were consecutively attached on the outer side of the heaters in order to prevent the heat loss from the heater. It can be concluded that when the centrifugal acceleration increases, the thermal resistance continuously decreases since the condensate flows back to the evaporator section more rapidly.

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 A CFD analysis of blockage length on a partially blocked fuel rod

2019 ◽  
Vol 7 (2B) ◽  
Author(s):  
Nikolas Lymberis Scuro ◽  
Pedro Ernesto Umbehaun ◽  
Edvaldo Angelo ◽  
Gabriel Angelo ◽  
Delvonei Alves de Andrade
Keyword(s):  
Steady State ◽  
Hydraulic Properties ◽  
Temperature Drop ◽  
Cfd Analysis ◽  
Fuel Rods ◽  
Transient Conditions ◽  
Fuel Rod ◽  
Loss Of Coolant Accident ◽  
Ansys Cfx ◽  
Loss Of Coolant

After a loss of coolant accident (LOCA), fuel rods may balloon. The swelling can partially block the flow channel, affecting the coolability during reflood phase. In order to analyze the influence of blockage length, using a radial blockage of 90%, varying just the blockage length, many steady state numerical simulations has been done using Ansys-CFX code to verify thermal-hydraulic properties according to different forced cooled conditions. Temperature peaks are observed on cladding, followed by a temperature drop. A 5x5 fuel assembly, with 9 centered ballooned fuel rod, flow redistribution inside channels can also be captured, indicating an overheating zone. Therefore, this study conclude, for the same boundary conditions, the longer the blockage length originated after LOCA events, the higher are the clad temperatures, indicating the possibility of overheat during transient conditions on reflood.

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