Influence of Inserting the Heat Pipe Into the MH Particle Bed on Refrigeration Performance

2011 ◽  
Author(s):  
Sangchul Bae ◽  
Eiji Morita ◽  
Keisuke Ishikawa ◽  
Yusuke Haruna ◽  
Masafumi Katsuta
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Carbon Fiber ◽  
Heat Pipe ◽  
Effective Thermal Conductivity ◽  
Refrigeration System ◽  
Transfer Enhancement ◽  
Heat Transfer Characteristics ◽  
Particle Bed ◽  
Cooling Part

In the refrigeration and air conditioning fields, the needs of energy conservation and renewable energy spread have become stronger recently. In this study, we aim at the development of the heat driven type metal hydride (abbr, MH) that can be driven by the low temperature exhausted heat or solar heat under 100°C. In order to commercialize this system, the heat transfer characteristics and the activation characteristics of MH particle bed must be more improved, and production cost must be more reduced. In this study, we use the two heat transfer enhancement methods for improving the low effective thermal conductivity of MH particle bed. One is by heat pipe (abbr., HP) and another is by brush type carbon fiber. HP is inserted into heat source part MH (abbr., MH1). By this method, we aim not only to enhance the heat transfer of MH1 particle bed but also to achieve the temperature uniformity of MH1 particle one. The effective thermal conductivity of cooling part MH (abbr., MH2) particle bed is enhanced by inserting the brush type carbon fiber. The influence of these heat transfer methods on our MH refrigeration system is estimated by measurement and calculation.

scholarly journals Study of Thermal Performance of Closed Loop Pulsating Heat Pipe using Computational Fluid Dynamics

2021 ◽  
Vol 9 (9) ◽  
pp. 1384-1388
Author(s):  
K. C. Giri
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Thermal Conductivity ◽  
Heat Flux ◽  
Heat Pipe ◽  
Closed Loop ◽  
Filling Ratio ◽  
Pulsating Heat Pipe ◽  
Heat Transfer Characteristics ◽  
Different Temperatures

Abstract: Pulsating heat pipe is a heat transfer device which works on two principles that is phase transition and thermal conductivity which transfer heat effectively at different temperatures. Different factors affect the thermal performance of pulsating heat pipe. So, various researchers tried to enhance thermal conductivity by changing parameters such as working fluids, filling ratio, etc. Analysis of heat transfer characteristics of closed loop pulsating heat pipe (CLPHP) is to be carried out by using Computational Fluid Dynamics. The CLPHP is to be modelled on ANSYS Workbench, the flow of CLPHP is to be observed under specific boundary conditions by using ANSYS Fluent software. Acetone and Water are taken as the working fluid with 70% filling ratio at ambient temperature 30° C and the heat flux of 200 W is supplied at evaporator. Also, the analysis has been done to know the behaviour of PHPs under varying supply of heat flux at evaporator (inlet), the output heat flux is obtained at condenser (outlet) and find out how the heat flux is varying at different temperatures. CFD results shows the heat transfer characteristics observing the performance of CLPHP is a numerical manner. The obtained CFD results are compared with the experimental. The outputs of the simulations are plotted in graphs and outlines. Keywords: Closed Loop Pulsating Heat Pipe, CFD, Heat Transfer, ANSYS.

Thermal Characterization of Aluminum and Steel Foams

2012 ◽  
Author(s):  
James D. Playford ◽  
S. Midturi ◽  
S. B. Pidugu
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Accurate Determination ◽  
Thermal Characterization ◽  
Metal Foams ◽  
Published Data ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Energy Absorbers

Metallic foams are a new class of ultra-lightweight materials with potential applications in such industries as automobile, aerospace, and energy industries. These materials when realized in product form can serve as efficient heat exchanges, energy absorbers, and thermal protective and hydrogen storage devices. Accurate determination of thermal conductivity and understanding of heat transfer characteristics is important in designing such products incorporating metal foams. The present research characterizes the effective thermal conductivity and heat transfer characteristics of DUOCEL AL 6106-T6 and Stainless Steel 314 open cell foams by experiments at near room temperature conditions. The effective thermal conductivity of these materials has been determined experimentally. Thermal conductivity of metal foams increased with increasing mechanical stress. The effect of porosity on the thermal conductivity of ERG supplied aluminum and NASA-GRC supplied SS 314 are also studied and compared with the published data in literature, however, in our studies systematic dependency of porosity is not observed. Experiments also conducted to quantify forced convective heat transfer characteristics under laminar flow conditions. Heat transfer coefficient increases with increased Reynolds number but results are not conclusive in case of natural convection.

Nanofluids Suspensions: Possible Explanations for the Apparent Enhanced Effective Thermal Conductivity

2005 ◽  
Author(s):  
Peter Vadasz
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Conduction ◽  
Effective Thermal Conductivity ◽  
Heterogeneous Medium ◽  
Alternative Possibilities ◽  
Dual Phase ◽  
Transfer Enhancement ◽  
Scale Level ◽  
Macro Scale

The spectacular heat transfer enhancement revealed experimentally in naofluids suspensions is being investigated theoretically at the macro-scale level aiming at explaining the possible mechanisms that lead to such impressive experimental results. In particular, the possibility that Dual-Phase-Lagging heat conduction in the heterogeneous medium (nanofluid suspension) could have been the source of the excessively improved effective thermal conductivity of the suspension is shown to provide a viable explanation. The investigation of alternative possibilities is needed however prior to reaching an ultimate conclusion.

Heat Transfer Enhancement by Using Nanofluids in Heat Pipe - A Review

2014 ◽  
Vol 592-594 ◽  
pp. 932-938
Author(s):  
Balasao D. Kusure ◽  
R.M. Warkhedkar ◽  
Pravin R. Harde ◽  
P.K. Shirke
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Heat Transfer Enhancement ◽  
Recent Work ◽  
Base Fluid ◽  
Heat Transfer Characteristic ◽  
Transfer Characteristic ◽  
Hybrid Nanofluid ◽  
Transfer Enhancement ◽  
Heat Transfer Characteristics

Nanofluid is nanomaterial suspended in base fluid. Nanoparticle enhances various properties of base fluid mainly heat transfer characteristics. Also sometime nanoblends means hybrid nanofluid is used. This article mainly states how nanofluids are formed from nanoparticle and there types. This paper reviews and summaries the recent work in experimental and theoretical heat transfer characteristic of nanofluid as well as nanoblends and it is helpful in identifying the nanofluid that can be used in heat pipe for further research.

Enhancement of Thermal Conductivity by Using Polymer-Zeolite in Solid Adsorption Heat Pumps

1997 ◽  
Vol 119 (3) ◽  
pp. 627-629 ◽  
Author(s):  
E. J. Hu ◽  
D.-S. Zhu ◽  
X.-Y. Sang ◽  
L. Wang ◽  
Y.-K. Tan
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Transfer Enhancement ◽  
Effective Thermal Conductivity ◽  
Heat Pumps ◽  
Synthesis Process ◽  
Transfer Enhancement ◽  
New Synthesis ◽  
Zeolite Particle ◽  
Enhancement Method

A thermal conductivity augmentation technology for zeolite beds has been studied in this paper. To enhance the effective thermal conductivity of zeolite, the zeolite particle was coated with a thermal polymer material in a new synthesis process. It was found that the effective thermal conductivity of the polymerzeolite was increased two to three times, while its adsorptive ability remains the same. The results of the experiment show that the polymer synthesis technique could be used as a heat transfer enhancement method to improve thermal conductivity among zeolite particles.

Thermophysical Performances of Al2O3-Water Nanofluids and Its Heat Transfer Enhancement in Heat Pipe

2011 ◽  
Vol 688 ◽  
pp. 339-343 ◽  
Author(s):  
Dong Dong Li ◽  
Wei Lin Zhao ◽  
Jin Kai Li ◽  
Yan Xiang Guan ◽  
Zong Ming Liu
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Surface Tension ◽  
Heat Pipe ◽  
Heat Transfer Performance ◽  
Volume Concentration ◽  
Transfer Enhancement ◽  
Step Method ◽  
Increasing Temperature ◽  
The Heat Transfer Coefficient

Al2O3-water nanofluids with volume concentration of 0.1%~0.5% were prepared by a two-step method, the thermophysical parameters such as thermal conductivity, viscosity and surface tension were measured, The results showed that the thermal conductivity of Al2O3-water nanofluids increased with increasing temperature and volume concentration, while the viscosity decreased with increasing temperature but increased with increasing volume concentration, in contrast to the thermal conductivity, the surface tension significantly decreased with increasing temperature and volume concentration. Furthermore, Al2O3-water nanofluids with 0.5% volume concentration were added into heat pipe. The experimental measurements showed that the Al2O3-water nanofluids have improved the heat transfer performance of heat pipe and the heat transfer coefficient of the heat pipe with Al2O3-water nanofluids enhanced by 85.7% when compared with the heat pipe with deionized water.

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