A Novel Magnetic Cooling Device for Long Distance Heat Transfer

2021 ◽  
pp. 117777
Author(s):  
M.S. Pattanaik ◽  
S.K. Cheekati ◽  
V.B. Varma ◽  
R.V. Ramanujan
Keyword(s):  
Heat Transfer ◽  
Cooling Device ◽  
Long Distance ◽  
Magnetic Cooling

scholarly journals Highly Resolved Distribution of Heat Transfer for Turbine Leading Edge Film Cooling Including Reynolds Number and Blowing Rate Effects

1998 ◽  
Author(s):  
K. Jung ◽  
D. K. Hennecke
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Reynolds Number ◽  
Film Cooling ◽  
Heat Mass Transfer ◽  
Leading Edge ◽  
Transfer Coefficients ◽  
Complex Flow ◽  
Long Distance ◽  
Naphthalene Sublimation Technique

The effect of leading edge film cooling on heat transfer was experimentally investigated using the naphthalene sublimation technique. The experiments were performed on a symmetrical model of the leading edge suction side region of a high pressure turbine blade with one row of film cooling holes on each side. Two different lateral inclinations of the injection holes were studied: 0° and 45°. In order to build a data base for the validation and improvement of numerical computations, highly resolved distributions of the heat/mass transfer coefficients were measured. Reynolds numbers (based on hole diameter) were varied from 4000 to 8000 and blowing rate from 0.0 to 1.5. For better interpretation, the results were compared with injection-flow visualizations. Increasing the blowing rate causes more interaction between the jets and the mainstream, which creates higher jet turbulence at the exit of the holes resulting in a higher relative heat transfer. This increase remains constant over quite a long distance dependent on the Reynolds number. Increasing the Reynolds number keeps the jets closer to the wall resulting in higher relative heat transfer. The highly resolved heat/mass transfer distribution shows the influence of the complex flow field in the near hole region on the heat transfer values along the surface.

Experimental Investigation of Boiling Heat Transfer in a Liquid Chamber With Partially Soluble Nanofluids

2021 ◽  
Author(s):  
Noriyuki Unno ◽  
Kazuhisa Yuki ◽  
Risako Kibushi ◽  
Rika Nogita ◽  
Atsuyuki Mitani
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Boiling Heat Transfer ◽  
Electronic Devices ◽  
High Heat ◽  
Experimental Result ◽  
High Heat Flux ◽  
Promising Technique ◽  
Cooling Device ◽  
Cooling Devices

Abstract Boiling heat transfer (BHT) is a promising technique to remove a high heat flux emitted from next-generation electronic devices. However, critical heat flux (CHF) is a big problem in BHT because it restricts the maximum performance of the cooling devices using BHT. Nanofluid has been widely used to improve the CHF. In this study, the authors investigated the BHT of a compact cooling device at low pressure using a special nanofluid: that is made with partially soluble particles in water. The experimental result found that the CHF with the special nanofluid is 170 W/cm2 and is higher than that with nanofluid made with an insoluble nanoparticle.

Heat Transfer Model and Analysis of Oil-Immersed Electrical Transformers with Heat Pipe Radiator

2012 ◽  
Vol 516-517 ◽  
pp. 312-315
Author(s):  
Guang Hua Li ◽  
Hong Lei Liu ◽  
De Jian Wang
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Temperature Field ◽  
Heat Pipe ◽  
Heat Transfer Model ◽  
Transfer Model ◽  
Cooling Device ◽  
Transformer Design ◽  
Electrical Transformers ◽  
Good Agreement

This paper has formulated a heat transfer model for analyzing the cooling properties of a heat pipe cooling device of oil-immersed electrical transformer. Based on the model, the oil temperature field of a 30 KVA oil-immersed transformer has been numerical simulated, and experiments also had been conducted. Results showed that the numerical simulation has good agreement with experiment results. Results also showed that heat pipe radiator is feasible for oil-immersed electrical transformer cooling. The model can be used to analyze the oil temperature distribution properties in an oil-immersed electrical transformer with heat pipe cooling device, and provide theoretical guide for transformer design and improvement.

Evaporative Heat Transfer From Ten-Micron Micro-Channels

2005 ◽  
Author(s):  
T. A. Quy ◽  
D. A. Carpenter ◽  
C. D. Richards ◽  
D. F. Bahr ◽  
R. F. Richards
Keyword(s):  
Heat Transfer ◽  
Electrical Power ◽  
Ccd Camera ◽  
Working Fluid ◽  
Sensible Heat ◽  
Silicon Membrane ◽  
Long Distance ◽  
Liquid Front ◽  
Micro Channels ◽  
Evaporative Heat Transfer

Evaporative heat transfer from ten-micron square open-top micro-channels is investigated experimentally. The channels are fabricated by spinning ten microns of SU-8 on a two micron thick silicon membrane and using a photolithography process to create micro channels in radial and annular patterns. The working fluid, FC77, is pumped by capillary forces into the channels from a reservoir at the edge of the silicon membrane. Electrical power is dissipated in a thin-film heater in the center of the membrane. The liquid front of working fluid in the channels is visualized with a long-distance microscope and CCD camera. Sensible heat conducted radially out of the membrane is measured with two concentric annular PRT’s. The mass of working fluid evaporated from the micro-channels is determined gravimetrically. A global energy balance including latent and sensible heat transfer out of the system is then tabulated. The study shows that only five to ten percent of the power going into the membrane is carried away by evaporation while the remaining ninety to ninety-five percent of the power is conducted out along the membrane.

Long Distance Heat Transfer of Pump-Less Heat Transport Device Using Temperature-Sensitive Magnetic Fluids

2018 ◽  
Vol 2018 (0) ◽  
pp. GS3-1
Author(s):  
Yuhiro IWAMOTO ◽  
Hayaki NAKASUMI ◽  
Keita ODAI ◽  
Yasushi IDO ◽  
Hiroshi YAMAGUCHI
Keyword(s):  
Heat Transfer ◽  
Heat Transport ◽  
Magnetic Fluids ◽  
Temperature Sensitive ◽  
Long Distance ◽  
Transport Device

scholarly journals Optimum Composition of Vacuum Content in a Spiral-Like Flexible Chimney-Based LED Bulb1

2020 ◽  
pp. 1-9
Keyword(s):  
Heat Transfer ◽  
Analytical Model ◽  
Gas Flow ◽  
Junction Temperature ◽  
Experimental Result ◽  
The Finite Element Method ◽  
Cooling Device ◽  
Resistance Model ◽  
Huge Impact ◽  
Chimney Effect

This paper introduced the gas flow and optimization of a spiral-like flexible chimneybased LED bulb by a combined mathematical and experimental study. A mathematical model of spiral flexible LED bulb considering nature convection, radiation and heat transfer was established by the FLOEFD software based on the finite element method (FEM), and was also compared with the experimental result. The effect of chimney-self based and vacuum content on the thermal performance of a bulb was studied. A thermal resistance model was proposed for analytical model. Compared with the filament with a stretch height of 3cm, the chimney effect can reduce the average junction temperature of filament by 6.38 ℃ (through the experiment) and 6.48 ℃ (through the simulation) respectively. The results revealed that the chimney effect has a huge impact on the gas flow in the bulb. The cause of the phenomenon is that flexible LED filament can improve the gas flow by changing self-shape instead of other cooling device. A vacuum content was introduced in the bulb and composition was optimized by using analytical model. The filament temperature in optimized bulb could decrease 6 0C than full filled with helium.

scholarly journals Influence of fins designs, geometries and conditions on the performance of a plate-fin heat exchanger-experimental perspective

2019 ◽  
Vol 13 (1) ◽  
pp. 4368-4379
Author(s):  
M. I. N. Ma’arof ◽  
Girma T. Chala ◽  
Hazran Husain ◽  
Muhammad S. S. Mohamed
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Exchange ◽  
Simple Form ◽  
Surface Characteristics ◽  
Total Surface Area ◽  
Cooling Device ◽  
Quality Aspect ◽  
Efficient Heat Transfer

A fin heat exchanger is a simple form of cooling device that is built for efficient heat transfer from one medium to another. Generally, it involves medium such as fluid to perform heat exchange via convective heat transfer. This study is aimed at investigating the effects of diverse designs (arrangements of the fins), qualities (the total surface area of the fin for heat exchange) and conditions (the surface characteristics) of fin heat exchanger on the degree of heat transfer from the experimental perspective. The fin heat exchanger was fabricated and tested. It was observed that by varying the arrangement and condition of the fins, the rate of heat transfer could be affected. However, varying the quality of the fin didn’t have much impact. Nevertheless, the quality aspect of the fin heat exchanger could play a significant role for heat exchanger of larger in scale and dimension. The coating, that is the condition of the fins, aided in decreasing the temperature at a much higher margin at all fan speeds.  

scholarly journals Optimal ferrofluids for magnetic cooling devices

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
M. S. Pattanaik ◽  
V. B. Varma ◽  
S. K. Cheekati ◽  
V. Chaudhary ◽  
R. V. Ramanujan
Keyword(s):  
Heat Transfer ◽  
Magnetic Nanoparticle ◽  
Performance Metrics ◽  
Passive Cooling ◽  
Enhance Heat Transfer ◽  
Cooling Performance ◽  
Magnetic Cooling ◽  
Cooling Devices ◽  
Dimensional Parameters ◽  
Feco Nanoparticles

AbstractSuperior passive cooling technologies are urgently required to tackle device overheating, consequent performance degradation, and service life reduction. Magnetic cooling, governed by the thermomagnetic convection of a ferrofluid, is a promising emerging passive heat transfer technology to meet these challenges. Hence, we studied the performance metrics, non-dimensional parameters, and thermomagnetic cooling performance of various ferrite and metal-based ferrofluids. The magnetic pressure, friction factor, power transfer, and exergy loss were determined to predict the performance of such cooling devices. We also investigated the significance of the magnetic properties of the nanoparticles used in the ferrofluid on cooling performance. γ-Fe2O3, Fe3O4, and CoFe2O4 nanoparticles exhibited superior cooling performance among ferrite-based ferrofluids. FeCo nanoparticles had the best cooling performance for the case of metallic ferrofluids. The saturation magnetization of the magnetic nanoparticles is found to be a significant parameter to enhance heat transfer and heat load cooling. These results can be used to select the optimum magnetic nanoparticle-based ferrofluid for a specific magnetic cooling device application.

Film Thickness and Heat Transfer Measurements in a Spray Cooling System With R134a

2011 ◽  
Vol 133 (1) ◽  
Author(s):  
Eduardo Martínez-Galván ◽  
Juan Carlos Ramos ◽  
Raúl Antón ◽  
Rahmatollah Khodabandeh
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Film Thickness ◽  
High Speed ◽  
Average Nusselt Number ◽  
Cooling System ◽  
Spray Cooling ◽  
Heat Fluxes ◽  
Long Distance ◽  
Thickness Measurements

Experimental measurements in a spray cooling test rig have been carried out for several heat fluxes in the heater and different spray volumetric fluxes with the dielectric refrigerant R134a. Results of the heat transfer and the sprayed refrigerant film thickness measurements are presented. The film thickness measurements have been made with a high speed camera equipped with a long distance microscope. It has been found that there is a relation between the variation in the average Nusselt number and the film thickness along the spray cooling boiling curve. The heat transfer regimes along that curve are related not only with a variation in the average Nusselt number but also with changes in the film thickness. The qualitative analysis of those variations has served to understand better the heat transfer mechanisms occurring during the spray cooling.

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