Numerical Investigation of Heat Transfer Enhancement Inside the Pipes Filled With Radial Pore-Size Gradient Porous Materials

2018 ◽  
Vol 10 (5) ◽  
Author(s):  
Peiyong Ma ◽  
Baogang Wang ◽  
Shuilin Chen ◽  
Xianwen Zhang ◽  
Changfa Tao ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Porous Materials ◽  
Pore Size ◽  
Flow Resistance ◽  
Heat Transfer Performance ◽  
Evaluation Criteria ◽  
Field Synergy ◽  
Transfer Enhancement ◽  
Size Gradient ◽  
Opening Up

The gradient porous materials (GPMs)-filled pipe structure has been proved to be effective in improving the heat transfer ability and reducing pressure drop of fluid. A GPMs-filled pipe structure in which radial pore-size gradient increased nonlinearly has been proposed. The field synergy theory and tradeoff analysis on the efficiency of integrated heat transfer has been accomplished based on performance evaluation criteria (PEC). It was found that the ability of heat transfer was enhanced considerably, based on the pipe structure, in which the pore-size of porous materials increased as a parabolic opening up. The flow resistance was the lowest and the integrated heat transfer performance was the highest when radial pore-size gradient increasing as a parabolic opening down.

Thermal Analysis in Phase Change Materials (PCMs) Embedded With Metal Foams

2010 ◽  
Author(s):  
Y. Tian ◽  
C. Y. Zhao
Keyword(s):  
Heat Transfer ◽  
Heat Conduction ◽  
Natural Convection ◽  
Heat Transfer Enhancement ◽  
Flow Resistance ◽  
Phase Change Materials ◽  
Heat Transfer Performance ◽  
Metal Foams ◽  
Transfer Performance ◽  
Transfer Enhancement

The heat transfer enhancement for phase change materials (PCMs) has received increasing attention nowadays, since most of PCMs have low thermal conductivities which prolong the charging and discharging processes. Metal foams, as a sort of novel material with high thermal conductivity, are believed to be a promising solution to enhance the heat transfer performance of PCMs for thermal energy storage systems. The effects of natural convection on heat transfer enhancement for PCMs embedded with metal foams are investigated in this paper. The numerical investigation is based on the two-equation non-equilibrium heat transfer model, where the coupled heat conduction and natural convection in PCMs are considered at phase transition and liquid zones. The numerical results are validated by experimental data. In order to investigate the effect of metal foams on heat transfer, two different cases are compared in this study, which are the Case A (PCMs embedded with metal foams) and the Case B (pure PCMs). At the solid zone, heat conduction plays a dominant part because of natural convection’s absence, thus metal foams achieve much higher heat conduction rate than pure PCMs, and this can be attributed to the high thermal conductivity of metal foams skeleton and the heat can be quickly transferred through the foam solid structure to the whole domain of PCMs. At the two-phase zone and liquid zone, natural convection takes place and becomes the dominant heat transfer mode, but metal foam structures suppress the natural convection inside the PCMs owing to big flow resistance in metal foams. In spite of this suppression caused by metal foams, the overall heat transfer performance of Case A is still superior to the counterpart of Case B (pure PCMs), implying the enhancement of heat conduction offsets or exceeds the natural convection loss. The results show that the heat transfer enhancement due to the natural convection in PCMs embedded with metal foams is not as strong as expected, since metal foams have big flow resistance and the natural convection is suppressed. It also shows that better heat transfer performance can be achieved by using the metal foams of smaller porosity and bigger pore density. Last but not least, a series of detailed velocity and temperature profiles are given through numerical solutions, in order to present a vivid evolution of flow field and temperature profiles in the whole melting process.

Numerical Simulation and Field Synergy Analysis of Flow and Heat Transfer in a Vibratory Tube

2012 ◽  
Vol 516-517 ◽  
pp. 949-953
Author(s):  
Jiu Yang Yu ◽  
Li Jun Liu ◽  
Wei Lin ◽  
Qian Liu ◽  
Wen Hao Yang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Performance ◽  
Half Cycle ◽  
Transfer Performance ◽  
Field Synergy ◽  
Transfer Enhancement ◽  
Flow And Heat Transfer ◽  
Temperature Distributions ◽  
Optimum Heat ◽  
Vibration Parameters

The present paper focuses on the analysis of transient heat transfer and flow in a vibratory tube. The characteristics of flow and heat transfer are investigated by dynamic mesh of CFD (computational fluid dynamics) software FLUENT, the velocity and temperature distributions in a vibration cycle are analyzed by field synergy theory. The results indicate that the vibration parameters have great effect on heat transfer, and the tube vibration leads to heat transfer enhancement or reduction. Moreover, the optimum heat transfer performance inside tubes is obtained in a half-cycle when time phase is 90°.

scholarly journals Heat transfer enhancement of car radiator using aqua based magnesium oxide nanofluids

2015 ◽  
Vol 19 (6) ◽  
pp. 2039-2048 ◽  
Author(s):  
Hafiz Ali ◽  
Muhammad Azhar ◽  
Musab Saleem ◽  
Qazi Saeed ◽  
Ahmed Saieed
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Thermal Management ◽  
Heat Transfer Performance ◽  
Inlet Temperature ◽  
Fluid Temperature ◽  
Transfer Enhancement ◽  
Volumetric Concentration ◽  
Flow Rates ◽  
Transfer Rates

The focus of this research paper is on the application of water based MgO nanofluids for thermal management of a car radiator. Nanofluids of different volumetric concentrations (i.e. 0.06%, 0.09% and 0.12%) were prepared and then experimentally tested for their heat transfer performance in a car radiator. All concentrations showed enhancement in heat transfer compared to the pure base fluid. A peak heat transfer enhancement of 31% was obtained at 0.12 % volumetric concentration of MgO in basefluid. The fluid flow rate was kept in a range of 8-16 liter per minute. Lower flow rates resulted in greater heat transfer rates as compared to heat transfer rates at higher flow rates for the same volumetric concentration. Heat transfer rates were found weakly dependent on the inlet fluid temperature. An increase of 8?C in inlet temperature showed only a 6% increase in heat transfer rate.

scholarly journals CFD-BASED STUDY ON RELATIONSHIP BETWEEN COOLING PERFORMANCE OF PULSATING FLOW AND RIB HEIGHT MOUNTED IN MINI RECTANGULAR CHANNEL

2020 ◽  
Vol 1 (1) ◽  
pp. 26-29
Author(s):  
Shintaro Hayakawa ◽  
Takashi Fukue ◽  
Hidemi Shirakawa ◽  
Wakana Hiratsuka
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Performance ◽  
Rectangular Channel ◽  
The Body ◽  
Pulsating Flow ◽  
Cfd Analysis ◽  
Human Beings ◽  
Pumping Power ◽  
Transfer Enhancement ◽  
Cooling Performance

This study aims to develop a novel water-cooled device that increases heat transfer performance while inhibiting the increase of pumping power for next-generation electronic equipment. Our previous reports have reported that the combination of the pulsating flow, which is the unsteady flow that the supply flow rate is periodically changed likes a blood in the body of human beings, and the rib has higher cooling efficiency. In this report, in order to optimize the dimensions of the ribs from the viewpoint of the cooling performance, an investigation of the pulsating flow around the rib was conducted through 2D-CFD analysis while changing the height of the rib. It was found that the level of the heat transfer enhancement was dependent on the rib height.

scholarly journals Enhanced heat transfer characteristics of conjugated air jet impingement on a finned heat sink

2017 ◽  
Vol 21 (1 Part A) ◽  
pp. 279-288 ◽  
Author(s):  
Shuxia Qiu ◽  
Peng Xu ◽  
Liping Geng ◽  
Arun Mujumdar ◽  
Zhouting Jiang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Heat Sink ◽  
Heat Transfer Performance ◽  
Cooling System ◽  
Flow Characteristics ◽  
Jet Impingement ◽  
Transfer Performance ◽  
Transfer Enhancement ◽  
Air Jet

Air jet impingement is one of the effective cooling techniques employed in micro-electronic industry. To enhance the heat transfer performance, a cooling system with air jet impingement on a finned heat sink is evaluated via the computational fluid dynamics method. A two-dimensional confined slot air impinging on a finned flat plate is modeled. The numerical model is validated by comparison of the computed Nusselt number distribution on the impingement target with published experimental results. The flow characteristics and heat transfer performance of jet impingement on both of smooth and finned heat sinks are compared. It is observed that jet impingement over finned target plate improves the cooling performance significantly. A dimensionless heat transfer enhancement factor is introduced to quantify the effect of jet flow Reynolds number on the finned surface. The effect of rectangular fin dimensions on impingement heat transfer rate is discussed in order to optimize the cooling system. Also, the computed flow and thermal fields of the air impingement system are examined to explore the physical mechanisms for heat transfer enhancement.

Heat Transfer Enhancement of Finned Copper Foam/Paraffin Composite Phase Change Material

2021 ◽  
Vol 14 ◽  
Author(s):  
Tingting Wu ◽  
Yanxin Hu ◽  
Xianqing Liu ◽  
Changhong Wang ◽  
Zijin Zeng ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Transfer Rate ◽  
Flow Resistance ◽  
Phase Change Materials ◽  
Heat Transfer Performance ◽  
Melting Process ◽  
Copper Foam ◽  
Composite Phase Change Material ◽  
Change Material

Background: The employment of Phase Change Materials (PCMs) provides a potential selection for heat dissipation and energy storage. The main reason that hinders the wide application is the low thermal conductivity of PCMs. Combining the proper metal fin and copper foam, the fin/composite phase change material (Fin-CPCM) structure with good performance could be obtained. However, the flow resistance of liquid paraffin among the porous structure has seldom been reported, which will significantly affect the thermal performance inside the metal foam. Furthermore, the presence of porous metal foam is primarily helpful for enhancing the heat transfer process from the bottom heat source. The heat transfer rate is slow due to the one-dimensional heat transfer from the bottom. It should be beneficial for improving the heat transfer performance by adding external fins. Therefore, in the present study, a modified structure by combining the metal fin and copper foam is proposed to further accelerate the melting process and improve the temperature uniformity of the composite. Objective: The purpose of this study is to research the differences in the heat transfer performance among pure paraffin, Composite Phase Change Materials (CPCM) and fin/Composite Phase Change Material (Fin-CPCM) under different heating conditions, and the flow resistance of melting paraffin in copper foam. Methods: To experimentally research the differences in the heat transfer performance among pure paraffin, CPCM and Fin-CPCM under different heating conditions, a visual experimental platform was set up, and the flow resistance of melting paraffin in copper foam was also analyzed. In order to probe into the limits of the heat transfer capability of composite phase change materials, the temperature distribution of PCMs under constant heat fluxes and constant temperature conditions was studied. In addition, the evolution of the temperature distributions was visualized by using the infrared thermal imager at specific points during the melting process. Results: The experimental results showed that the maximum temperature of Fin-CPCM decreased by 21°C under the heat flux of 1500W/m2 compared with pure paraffin. At constant temperature heating conditions, the melting time of Fin-CPCM at a temperature of 75°C is about 2600s, which is 65% less than that of pure paraffin. Due to the presence of the external fins, which brings the advantage of improving the heat transfer rate, the experimental result exhibited the most uniform temperature distribution. Conclusion: The addition of copper foam can accelerate the melting process. The addition of external fins brings the advantage of improving the heat transfer rate, and can make the temperature distribution more uniform.

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