The Effect of Porous Material on the Improvement of the Micro-Chip Heat Dissipation

2008 ◽  
Author(s):  
Chyouhwu B. Huang ◽  
Hung-Shyong Chen ◽  
Szu-Ming Wu
Keyword(s):  
Heat Transfer ◽  
Porous Material ◽  
Porous Materials ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Heat Dissipation ◽  
Porous Ceramic ◽  
High Heat ◽  
Force Convection ◽  
Uninterruptible Power

Heat dissipation is a very important subject when dealing with industrial application especially in modern semiconductor related applications. Several techniques have been developed to solve the heat generated problem, such as heat dissipation device in IC packaging, high heat conductivity materials, heat tube, force convection, etc. Porous material is used in this study. Porous material is known to have large interior surface, therefore, with proper force convection; it can easily carry heat away. Micro porous ceramic (porous size: 490 μm) is attached to uninterruptible power supply (UPS) power chips. The increase of the heat dissipation rate improves UPS performance. Heat transfer properties comparisons for power chip with and without micro porous materials attached are studies. Also, heat transfer rate under different fan speeds (force convection) is studied. The results show that, heat transfer increases with the use of micro porous materials, the effectiveness ranges between 2–22%. Also, the heat transfer rate varies with air flow rate, the increase of heat transfer is about 4–6%. The dust effect was also performed; experimental results show that heat transfer rate will not be affected by the accumulated dust if a micro porous material is applied.

An Investigation of Thermal and Velocity Fields for a Confined Jet Over the RE Range of 1,000-24,000

2008 ◽  
Author(s):  
N. Jeffers ◽  
J. Punch ◽  
E. Walsh
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Local Heat Transfer ◽  
Local Heat ◽  
High Heat ◽  
Heat Fluxes ◽  
Hydrodynamic Characteristics ◽  
Plate Spacing ◽  
High Heat Transfer

Contemporary electronic systems currently generate high heat fluxes at component level. Impingement cooling is an effective way to generate high heat transfer coefficients in order to meet thermal constraints. This paper investigates the heat transfer and hydrodynamic characteristics of a confined impinging liquid jet with a nozzle-to-plate spacing (H/D) ratio of 0.5. A custom measurement facility was created to infer local heat transfer rates from infra-red images of a jet impinging on a 12.5μm thick stainless steel foil configured to generate uniform heat flux. Particle-Image Velocimetry (PIV) was performed in order to obtain quantitative velocity data within the jet. A series of experiments were run for Reynolds numbers (Re) in the range of 1,000–24,000 for a jet of 8 mm diameter (D). For Re > 4,000, the local heat transfer rate — in terms of Nusselt number (Nu) as a function of dimensionless radius (r/D) — had a plateau section between 0 < r/D < 0.6 followed by a peak at r/D ∼ 1.35. For higher Re the Nu peak exceeds that of the plateau section. For Re < 4,000, a plateau section exists between 0 < r/D < 0.4 followed by a shoulder located between 1 < r/D < 1.4. The PIV data for Re > 4,000 showed a strong vortex in the area of the secondary peak in Nu which was not present in the lower Re range. This phenomenon — the local peaks of heat transfer rate — has been previously reported in the literature with a degree of uncertainty as to the related fluid mechanics. This paper contributes to an understanding of the fluidic phenomenon responsible for the distribution of heat transfer rate in confined jets.

“A REVIEW OF HEAT DISSIPATION ANALYSIS BY VARYING GEOMETRICAL CONDITION OF CYLINDRICAL FIN”

IJOSTHE ◽  
2018 ◽  
Vol 5 (4) ◽  
pp. 7
Author(s):  
Swarnik Mehar ◽  
Pankaj Mishra
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Heat Transfer Rate ◽  
Dissipation Rate ◽  
Transfer Rate ◽  
Heat Dissipation ◽  
Heat Engine ◽  
Total Heat Flow ◽  
Geometrical Condition ◽  
Interesting Task

If the heat in the heat engine is not removed properly, it causes the development of the detonation and eventually reduces the efficiency of the engine, so that the heat dissipation rate of the cylinder an important and interesting task is the option. The cylinder of the engine is one of the most important automotive components, variations of high temperature and thermal loads. To cool the cylinder, the ribs are provided on the surface of the cylinder, to increase the rate of heat transfer. By a thermal analysis of the motor cylinder and the ribs that surround it, it is useful to know the heat transfer rate and the temperature distribution inside the cylinder. We know that we can increase the heat dissipation rate by increasing the surface so it is very difficult to design such a complex motor. The main objective of this project is to analyze thermal properties such as thermal directed flow, total heat flow and temperature distribution. The cooling mechanism of the air cooled engine depends mainly on the design of the cylinder head and the block ribs. The cooling fins are used to increase the heat transfer rate of the specified surface. The life and efficiency of the engine can be improved by efficient cooling. The finite element method was used using the ANSYS software as a simulation tool for analysis.

Study on Condensation Behavior in Two-Phase Flow Through a Microchannel

2008 ◽  
Author(s):  
Genki Takeuchi ◽  
Akiko Fujiwara ◽  
Yutaka Abe ◽  
Yutaka Suzuki
Keyword(s):  
Heat Transfer ◽  
High Pressure ◽  
Heat Exchanger ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Capillary Tube ◽  
High Heat ◽  
Flow Patterns ◽  
Rate Condition ◽  
High Heat Transfer

It is requested to develop a small and high performance heat exchanger for small size energy equipments such as fuel cells and CO2 heat pumps, et.al... In author’s previous studies, a high pressure resistant microchannel layers stacked heat exchanger has been developed. The heat exchanger is manufactured by diffusion bond technique. It can be used under high pressure condition larger than 15 MPa. Due to the high pressure resistance, the device can be applied for high flow rate condition with boiling and condensation. The objectives of the present study are to estimate the heat transfer performance of the heat exchanger and to investigate the thermal hydraulic behavior in the microchannel. The flow pattern in a glass capillary tube is observed by fabricating visualization system. As the results, it is measured that the present device attained high heat transfer quantity of approximately 7000 W on steam condensation despite the weight is only 230 g. The measurement results clarified that the device achieves very high heat transfer rate of hundreds times larger than that of the existing heat exchanger. Furthermore, visualization experiment with single glass pipe is conducted to clarify the flow condensation behavior in the microchannel. In the experiment, the microchannel of Pyrex glass is surrounded by the subcooling water. The flow patterns can visualized from the side of the microchannel. Flow patterns observations are conducted for various inlet pressure and temperatures of the subcooling water. It is observed that the continuous flow transition from annular and injection flow to slug-bubble flow in the microchannel. The reason of large heat transfer rate per unit volume is discussed as relating to narrow interval of each microchannels and small thermal resistance.

Convective heat transfer in a porous enclosure saturated by nanofluid with different heat sources

2018 ◽  
Vol 7 (1) ◽  
pp. 1-16 ◽  
Author(s):  
M. Muthtamilselvan ◽  
S. Sureshkumar
Keyword(s):  
Heat Transfer ◽  
Heat Source ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
High Heat ◽  
Heated Wall ◽  
Left Wall ◽  
High Heat Transfer

Abstract The present study is proposed to investigate the effects of various lengths and different locations of the heater on the left sidewall in a square lid-driven porous cavity filled with nanofluid. A higher temperature is maintained on the left wall where three different lengths and three different locations of the heat source are considered for the analysis. The right wall is kept at a lower temperature while the top and bottom walls, and the remaining portions of the heated wall are adiabatic. The governing equations are solved by finite volume method. The results show that among the different lengths of the heat source, an enhancement in the heat transfer rate is observed only for the length LH = 1/3 of the heat source. In the case of location of the heat source, the overall heat transfer rate is increased when the heat source is located at the top of the hot wall. For Ri = 1 and 0.01, a better heat transfer rate is obtained when the heat source is placed at the top of the hot wall whereas for Ri = 100, it occurs when the heating portion is at the middle of the hot wall. As the solid volume fraction increases, the viscosity of the fluid is increased, which causes a reduction in the flow intensity. An addition of nanoparticles in the base fluid enhances the overall heat transfer rate significantly for all Da considered. The permeability of the porous medium plays a major role in convection of nanofluid than porosity. A high heat transfer rate (57.26%) is attained for Da = 10−1 and χ = 0.06.

scholarly journals STATIC THERMAL ANALYSIS OF FINS MODELS USING ANSYS

2020 ◽  
Author(s):  
Rajat Kumar ◽  
Devendra Singh ◽  
Ajay Kumar Sharma
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Heat Dissipation ◽  
Thermal Stresses ◽  
Temperature Variations ◽  
Finite Element Software ◽  
Pin Fins ◽  
Over The Top

The Engine chamber is one of the essential engine components, that is subjected to over the top temperature differences and thermal stresses. Fins are set on the surface of the cylinder to improve the quantity of heat exchange by convection. When fuel is burned in an engine, heat is produced. Additional heat is also generated by friction between the moving parts. In air-cooled I.C engine, extended surfaces called fins are provided at the periphery of engine cylinder to increase heat transfer rate. That is why the analysis of fin is important to increase the heat transfer rate. The main of aim of this work is to study various researches done in past to improve heat transfer rate of cooling fins by changing cylinder fin geometry and material. In the present work, Experiments have been performed to discover the temperature variations inside the fins made in four kind geometries (plate Fins, Circular Pin fins, plate fins with holes, and draft Pin fins) and consistent state heat exchange examination has been studied utilizing a finite element software ANSYS to test and approve results. The temperature variations at various areas of fins models are evaluated by FEM and compared models of fins performance by heat flux and temperature variations obtained by experimentally in Analysis. The principle implemented in this project is to expand the heat dissipation rate by utilizing the wind flow. The main aim of the study is to enhance the thermal properties by shifting geometry, material, and design of fins

scholarly journals NUMERICAL INVESTIGATION OF THERMOHYDRAULIC PERFORMANCE OF TRIPLE CONCENTRIC-TUBE HEAT EXCHANGER WITH LONGITUDINAL FINS

2021 ◽  
Vol 16 (8) ◽  
Author(s):  
Shafquat Hussain
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Crude Oil ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
High Heat ◽  
Diesel Oil ◽  
Engine Oil ◽  
Tube Heat Exchanger ◽  
High Heat Transfer

In this work, a triple concentric-tube heat exchanger (TCTH) with or without the application of longitudinal fins is numerically studied concerning its thermohydraulic performance. The computational fluid dynamics (CFD) program, Ansys FLUENT was used to perform the simulations to study the heat transfer enhancement using three different types of hot fluids, i.e. Crude oil, engine oil, and light diesel oil. The validated numerical model was first employed to investigate the heat transfer performance of unfinned TCTHE. Then, longitudinal fins were modeled and investigated for comparative analyses of the thermohydraulic performances of both constructions. To predict the heat exchanger performance, key parameters such as heat flux and temperature field distribution were evaluated. Results revealed that modifying the heat exchanger with longitudinal fins on the tube surface dramatically improves its heat transfer rate. Therefore, this research is designed to keep in view further exploring the potential of longitudinal fins in obtaining an improved performance from these types of heat exchanger devices. The results showed that the crude oil fluid has high heat transfer rate than the other two fluids light diesel oil and engine oil. With the application of fins on the tubes’ surfaces, a significant heat transfer exchange among the fluids streams is observed.

scholarly journals Enhancement of heat transfer in a synthetic jet actuated by piston cylinder

2021 ◽  
Vol 13 (9) ◽  
pp. 168781402110491
Author(s):  
Arun Jacob ◽  
KA Shafi ◽  
KE Reby Roy
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Heat Dissipation ◽  
Flow Direction ◽  
Experimental Studies ◽  
Jet Impingement ◽  
Stokes Number ◽  
Synthetic Jet ◽  
Stroke Length

Modern electronics demand more powerful cooling systems due to an increase in heat dissipation. The traditional cooling techniques reached their limit and the synthetic jet impingement arises as a promising method for cooling of modern electronic systems. This paper presents the experimental studies on the heat transfer characteristics of a synthetic jet. The synthetic jet is driven by a piston actuator. The effects of dimensionless parameters like the distance between the orifice and heater plate (Z/D), the ratio of stroke length to diameter of orifice ( L/D), Stokes number, and Reynolds number are discussed. The effect of orifice geometry, number of orifices are also presented. The results indicate that the Z/D and Stokes number have a significant influence on the heat transfer rate. As the Stokes number increases the heat transfer increases due to an increase in axial momentum and turbulence in the flow direction. For circular orifice and at high Z/D, the L/D ratio should be higher for better heat transfer. Rectangular orifice performs better than square and circular geometries. When compared to single jet multiple jets have a higher heat transfer rate. Maximum and minimum values of normalized pressure ( Pnr) are achieved for high Stokes number and smaller areas of the orifice.

Heat Transfer Rate Enhancement of an Air Cooled Four Stroke SI Engine by Geometrically Modified Fins-A Review

2018 ◽  
Vol 4 (5) ◽  
pp. 4 ◽  
Author(s):  
Roshan Kumar Nirala ,Pushpendra Kumar Jain2
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Rate ◽  
Dissipation Rate ◽  
Transfer Rate ◽  
Heat Dissipation ◽  
Thermal Stresses ◽  
Working Fluid ◽  
Si Engine ◽  
Engine Cylinder ◽  
Engine Components

The engine cylinder is one of the major I C engine components, which is subjected to high temperature variations and thermal stresses. To cool the cylinder, fins are provided on the surface of the cylinder to increase the rate of heat transfer. By doing thermal analysis on the engine cylinder fins, it is helpful to know the heat dissipation inside the cylinder. The main aim of the paper is to increase the heat dissipation rate by using the invisible working fluid of air. It is observed that, by increasing the surface area the heat dissipation rate increases, further the main purpose of using these cooling fins is to cool the engine cylinder by air. This paper  presents a review to increase heat transfer rate in a four stroke S I engine by using geometrically modified fins

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