A SIMPLE MATHEMATICAL MODEL TO PREDICT HEAT PIPE MAXIMUM HEAT TRANSFER, EQUIVALENT THERMAL CONDUCTIVITY, AND THERMAL RESISTANCE

2016 ◽  
Vol 7 (1-2) ◽  
pp. 45-55
Author(s):  
Masataka Mochizuki ◽  
Thang Nguyen ◽  
Yuji Saito ◽  
Tien Nguyen ◽  
Vijit Wuttijumnong
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Mathematical Model ◽  
Thermal Resistance ◽  
Heat Pipe ◽  
Simple Mathematical Model ◽  
Equivalent Thermal Conductivity ◽  
Maximum Heat ◽  
Maximum Heat Transfer

scholarly journals Thermal performance prediction of heat pipe with TiO2 nanofluids using RSM

2021 ◽  
pp. 199-199
Author(s):  
Lakshmi Reddy ◽  
Srinivasa Bayyapureddy Reddy ◽  
Kakumani Govindarajulu
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Thermal Resistance ◽  
Transfer Coefficient ◽  
Heat Pipe ◽  
Thermal Performance ◽  
Tilt Angle ◽  
Heat Load ◽  
Maximum Heat ◽  
Maximum Heat Transfer

Heat pipe is a two phase heat transfer device with high effective thermal conductivity and transfer huge amount of heat with minimum temperature gradient in between evaporator and condenser section. This paper objective is to predict the thermal performance in terms of thermal resistance (R) and heat transfer coefficient (h) of screen mesh wick heat pipe with DI water-TiO2 as working fluid. The input process parameters of heat pipe such as heat load (Q), tilt angle (?) and concentration of nanofluid (?) were modeled and optimized by utilizing Response Surface Methodology (RSM) with MiniTab-17 software to attain minimum thermal resistance and maximum heat transfer coefficient. The minimum thermal resistance of 0.1764 0C/W and maximum heat transfer coefficient of 1411.52 W/m2 0C was obtained under the optimized conditions of 200 W heat load, 57.20 tilt angle and 0.159 vol. % concentration of nano-fluid.

A Review on Nanofluid Heat Pipe

2014 ◽  
Author(s):  
Maryam Shafahi ◽  
Kevin Anderson ◽  
Ali Borna ◽  
Michael Lee ◽  
Alex Kim ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Pipe ◽  
Thermal Performance ◽  
Heat Exchangers ◽  
Working Fluid ◽  
Maximum Heat ◽  
Maximum Heat Transfer ◽  
Medical Instruments ◽  
Thermo Physical Properties

This paper reviews the improvement in the heat pipe’s performance using nanofluid as the working fluid. The use of nanofluid enhances heat transfer in the heat pipe due to its improved thermo-physical properties, such as a higher thermal conductivity. Nanofluids proved to be the innovative approach to a variety of applications, such as electronics, medical instruments, and heat exchangers. The influence of different nanoparticles on heat pipe’s performance has been studied. Utilizing nanofluid as the working fluid leads to a significant reduction in heat pipe thermal resistance, an increase in maximum heat transfer, and an improvement of heat pipe thermal performance.

scholarly journals Investigation of the novelty of latent functionally thermal fluids as alternative to nanofluids in natural convective flows

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Zoubida Haddad ◽  
Farida Iachachene ◽  
Eiyad Abu-Nada ◽  
Ioan Pop
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Transfer Enhancement ◽  
Volume Fraction ◽  
Heat Of Fusion ◽  
Transfer Enhancement ◽  
Maximum Heat ◽  
Thermal Fluids ◽  
Maximum Heat Transfer ◽  
Wide Range

AbstractThis paper presents a detailed comparison between the latent functionally thermal fluids (LFTFs) and nanofluids in terms of heat transfer enhancement. The problem used to carry the comparison is natural convection in a differentially heated cavity where LFTFs and nanofluids are considered the working fluids. The nanofluid mixture consists of Al2O3 nanoparticles and water, whereas the LFTF mixture consists of a suspension of nanoencapsulated phase change material (NEPCMs) in water. The thermophysical properties of the LFTFs are derived from available experimental data in literature. The NEPCMs consist of n-nonadecane as PCM and poly(styrene-co-methacrylic acid) as shell material for the encapsulation. Finite volume method is used to solve the governing equations of the LFTFs and the nanofluid. The computations covered a wide range of Rayleigh number, 104 ≤ Ra ≤ 107, and nanoparticle volume fraction ranging between 0 and 1.69%. It was found that the LFTFs give substantial heat transfer enhancement compared to nanofluids, where the maximum heat transfer enhancement of 13% was observed over nanofluids. Though the thermal conductivity of LFTFs was 15 times smaller than that of the base fluid, a significant enhancement in thermal conductivity was observed. This enhancement was attributed to the high latent heat of fusion of the LFTFs which increased the energy transport within the cavity and accordingly the thermal conductivity of the LFTFs.

Convective Heat Transfer Analysis of Open Cell Metal Foam for Solar Air Heaters

Solar Energy ◽  
2003 ◽  
Author(s):  
Nihad Dukhan ◽  
Pablo D. Quinones
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Metal Foam ◽  
Heat Transfer Analysis ◽  
Transfer Model ◽  
Aluminum Foams ◽  
Maximum Heat ◽  
Open Cell ◽  
Maximum Heat Transfer

A one-dimensional heat transfer model for open-cell metal foam is presented. Three aluminum foams having different areas, relative densities, ligament diameters, and number of pores per inch were analyzed. The effective thermal conductivity and the heat transfer increased with the number of pores per inch. The effective thermal conductivity of the foams can be up to four times higher than that of solid aluminum. The resulting improvement in heat transfer can be as high as 50 percent. The maximum heat transfer for the aluminum foams occurs at a pore Reynolds number of 52. The heat transfer, in addition, becomes insensitive to the flow regime for pore Reynolds numbers beyond 200.

Investigation on Heat Transfer Performance of Heat Pipe Grinding Wheel in Dry Grinding

2016 ◽  
Vol 138 (11) ◽  
Author(s):  
Qingshan He ◽  
Yucan Fu ◽  
Jiajia Chen ◽  
Wei Zhang
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Pipe ◽  
Heat Transfer Performance ◽  
Grinding Wheel ◽  
Grinding Temperature ◽  
Transfer Performance ◽  
Equivalent Thermal Conductivity ◽  
Dry Grinding ◽  
Pipe Heat

The use of fluid in grinding enhances heat exchange at the contact zone and reduces grinding temperature. However, the massive use of fluid can cause negative influences on environment and machining cost. In this paper, a novel method of reducing grinding temperature based on heat pipe technology is proposed. One new heat pipe grinding wheel and its heat transfer principle are briefly introduced. A heat transfer mathematical model is established to calculate equivalent thermal conductivity of heat pipe grinding wheel. Compared with the wheel without heat pipe, heat transfer effect of heat pipe grinding wheel is presented, and the influences of heat flux input, cooling condition, wheel speed, and liquid film thickness on heat transfer performance are investigated. Furthermore, dry grinding experiments with two different wheels are conducted to verify the cooling effectiveness on grinding temperature. The results show that thermal conductivity of the wheel with heat pipe can be greatly improved compared to the one without heat pipe; heat transfer performance of heat pipe grinding wheel can change with different grinding conditions; meanwhile, grinding temperatures can be significantly decreased by 50% in dry grinding compared with the wheel without heat pipe.

Two Different Types of Axially-Grooved Heat Pipes and Thermal Performance Comparison

2007 ◽  
Author(s):  
Yong Chi ◽  
Yong Tang ◽  
Le-Lun Jiang ◽  
Zhen-Ping Wan ◽  
Min-Qiang Pan
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Thermal Performance ◽  
Heat Pipes ◽  
Performance Comparison ◽  
Maximum Heat ◽  
Horizontal Orientation ◽  
Maximum Heat Transfer ◽  
Inclination Angles ◽  
The One

Heat pipes have been widely applied to the cooling of microelectronics chips at present. In this paper, to conduct a comparative study on heat pipe performance with different groove structures, two types of axially-grooved heat pipe were manufactured by spinning and secondary broaching respectively. The heat pipe A formed by spinning has homogeneous 55 U-shaped grooves on the inner wall. The grooves with depth of 220μm, width of 200μm and groove angle of 15° are smooth. While the inner wall of the heat pipe B fabricated by secondary broaching is scored and the grooves are heterogeneous. The comparison of heat transfer performance and start-up of two heat pipes are analyzed and investigated under different orientations and heat loads. Experimental results show that the heat pipe formed by spinning has a stronger level of heat transfer capabilities than heat pipe formed by secondary broaching. The maximum heat transfer rate for the heat pipe formed by spinning is almost 70Watts, while the one for the heat pipe fabricated by secondary broaching is only 20Watts. The minimum thermal resistance of the heat pipe A and B was 0.020°C/W and 0.068°C/W respectively. At positive inclination angles in gravity-assisted condition, the thermal performance of both two heat pipe have not obvious difference with at horizontal orientation. But at negative inclination angles in anti-gravity condition, the gravity will play an important role on grooved heat pipes.

A Novel Quick Qmax Test Method and Experimental Investigation of Heat Pipes

2005 ◽  
Author(s):  
Yao-Chen Chan ◽  
Wei-Keng Lin
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Wall Temperature ◽  
Transfer Rate ◽  
Heat Pipes ◽  
Adiabatic Temperature ◽  
Test Method ◽  
Maximum Heat ◽  
Maximum Heat Transfer ◽  
Dry Out

In traditional heat pipe performance test, to keep an adiabatic temperature at a constant value, the evaporator wall temperature would be slowly increased when the thermal power was step input to the evaporator of the heat pipe. The maximum heat transfer rate (Qmax) was then defined that when the evaporator wall temperature rapidly increased at a certain amount of power input to the heat pipe. However, it is not easy to distinguish this sharp increased curve and sometimes result in the wrong Qmax data. In addition, it took too long for waiting the evaporator temperature approach to a steady state, thus this process could not use be for the fully check Qmax of the heat pipe. In this paper, we propose a novel quick test method to predict the maximum heat dissipation of the heat pipes namely Dynamic-Temperature-Tracing (D.T.T). The concept of the D.T.T was when we tracing the evaporator and the adiabatic wall temperature, these two temperature curves should be the same trend before the dry-out phenomena was occurred. Theoretically, when the dry-out start to occur in the heat pipe, the adiabatic temperature profile was no longer kept the same temperature profile as that of the evaporator. Hence, the maximum heat dissipate ability of the heat pipe was then easy to obtained at this measuring adiabatic temperature. The data were also compared with those obtained from the traditional standard method at the same equivalent evaporator length, condenser length and adiabatic temperature. In this experiments, sinter powder and groove heat pipes with diameter 6mm 8mm and 200mm length were selected as the capillary wick structure. Comparing with traditional method results, the errors of maximum heat transfer rate are less than 15%. The results also shown D.T.T. method is much fast and reliable compare with the traditional test method.   This paper was also originally published as part of the Proceedings of the ASME 2005 Pacific Rim Technical Conference and Exhibition on Integration and Packaging of MEMS, NEMS, and Electronic Systems.

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