scholarly journals Analysing the Behaviour of Copper Oxide-Thermal Oil on Forced Convection and Pressure Drop in Upward and Downward Flow in Plain and Microfin Tube

2021 ◽  
Vol 15 (1) ◽  
Author(s):  
Vikash Agrawal
Keyword(s):  
Pressure Drop ◽  
Copper Oxide ◽  
Forced Convection ◽  
Downward Flow ◽  
Thermal Oil

scholarly journals Evaluation of Active Heat Sinks Design under Forced Convection—Effect of Geometric and Boundary Parameters

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2041
Author(s):  
Eva C. Silva ◽  
Álvaro M. Sampaio ◽  
António J. Pontes
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Additive Manufacturing ◽  
Pressure Drop ◽  
Forced Convection ◽  
Thermal Performance ◽  
Heat Sinks ◽  
Trapezoidal Shape ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations

This study shows the performance of heat sinks (HS) with different designs under forced convection, varying geometric and boundary parameters, via computational fluid dynamics simulations. Initially, a complete and detailed analysis of the thermal performance of various conventional HS designs was taken. Afterwards, HS designs were modified following some additive manufacturing approaches. The HS performance was compared by measuring their temperatures and pressure drop after 15 s. Smaller diameters/thicknesses and larger fins/pins spacing provided better results. For fins HS, the use of radial fins, with an inverted trapezoidal shape and with larger holes was advantageous. Regarding pins HS, the best option contemplated circular pins in combination with frontal holes in their structure. Additionally, lattice HS, only possible to be produced by additive manufacturing, was also studied. Lower temperatures were obtained with a hexagon unit cell. Lastly, a comparison between the best HS in each category showed a lower thermal resistance for lattice HS. Despite the increase of at least 38% in pressure drop, a consequence of its frontal area, the temperature was 26% and 56% lower when compared to conventional pins and fins HS, respectively, and 9% and 28% lower when compared to the best pins and best fins of this study.

Pressure Drop During Forced Convection Boiling of R-12 Under Swirl Flow

1982 ◽  
Vol 104 (4) ◽  
pp. 758-762 ◽  
Author(s):  
K. N. Agrawal ◽  
H. K. Varma ◽  
S. Lal
Keyword(s):  
Pressure Drop ◽  
Forced Convection ◽  
Flow Boiling ◽  
Horizontal Tube ◽  
Swirl Flow ◽  
Flow Data ◽  
Nelson Model ◽  
Twisted Tapes ◽  
Twist Ratio ◽  
Flow Pressure

This investigation deals with the pressure drop during forced convection boiling of R-12 under swirl flow inside a horizontal tube. Plain flow and swirl flow pressure drop data are reported for an electrically heated, horizontal, stainless steel, round test-section fitted with twisted tapes having twist ratios from 3.76 to 10.15. A correlation has been presented expressing the swirl flow boiling pressure drop in terms of the twist ratio and the plain flow boiling pressure drop calculated by the Martinelli-Nelson model. The proposed correlation predicts the swirl flow data to within ± 20 percent of the observed values.

Experimental Study on Forced Convection Heat Transfer Inside Horizontal Tubes in an Absorption/Compression Heat Pump

2002 ◽  
Vol 124 (5) ◽  
pp. 975-978 ◽  
Author(s):  
Li Yong and ◽  
K. Sumathy
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Forced Convection ◽  
Experimental Results ◽  
Working Fluid ◽  
Large Temperature ◽  
Absorption Process ◽  
Transfer Coefficients ◽  
Tube Heat Exchanger ◽  
Heat Transfer Coefficients

Quasi-local absorption heat transfer coefficients and pressure drop inside a horizontal tube absorber have been investigated experimentally, with R-22/DMA as the working pair. The absorber is a counterflow coaxial tube-in-tube heat-exchanger with the working fluid flowing in the inner tube while the water moves through the annulus. A large temperature gliding has been experienced during the absorption process. Experimental results show that the heat transfer coefficient of the forced convective vapor absorption process is higher compared to the vertical falling film absorption. A qualitative study is made to analyze the effect of mass flux, vapor quality and solution concentration on pressure drop and heat transfer coefficients. On the basis of the experimental results, a new correlation is proposed whereby the two-phase heat transfer is taken as a product of the forced convection of the absorption and the combined effect of heat and mass transfer at the interface. The correlation is found to predict the experimental data almost within 30 percent.

A Numerical Study of the Thermal Performance of Two Stationary Insert Designs in Internal Compressible Flows

2009 ◽  
Author(s):  
Emad Y. Tanbour ◽  
Ramin K. Rahmani
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Heat Transfer Enhancement ◽  
Forced Convection ◽  
Thermal Performance ◽  
Compressible Flows ◽  
Convection Heat Transfer ◽  
Convection Heat ◽  
Transfer Enhancement ◽  
Stationary Heat Transfer

Enhancement of the natural and forced convection heat transfer has been the subject of numerous academic and industrial studies. Air blenders, mechanical agitators, and static mixers have been developed to increase the forced convection heat transfer rate in compressible and incompressible flows. Stationary inserts can be efficiently employed as heat transfer enhancement devices in the natural convection systems. Generally, a stationary heat transfer enhancement insert consists of a number of equal motionless segments, placed inside of a pipe in order to control flowing fluid streams. These devices have low maintenance and operating costs, low space requirements and no moving parts. A range of designs exists for a wide range of specific applications. The shape of the elements determines the character of the fluid motion and thus determines thermal effectiveness of the insert. There are several key parameters that may be considered in the design procedure of a heat transfer enhancement insert, which lead to significant differences in the performance of various designs. An ideal insert, for natural conventional heat transfer in compressible flow applications, provides a higher rate of heat transfer and a thermally homogenous fluid with minimized pressure drop and required space. To choose an insert for a given application or in order to design a new insert, besides experimentation, it is possible to use Computational Fluid Dynamics to study the insert performance. This paper presents the outcomes of the numerical studies on industrial stationary heat transfer enhancement inserts and illustrates how a heat transfer enhancement insert can improve the heat transfer in buoyancy driven compressible flows. Using different measuring tools, thermal performance of two different inserts (twisted and helix) are studied. It is shown that the helix design leads to a higher rate of heat transfer, while causes a lower pressure drop in the flowfield, suggesting the insert effectiveness is higher for the helix design, compared to a twisted plate.

3D Printed Architected Heat Sinks Cooling Performance in Free and Forced Convection Environments

2020 ◽  
Author(s):  
Mohamed I. Hassan Ali ◽  
Oraib Al-Ketan ◽  
Mohamad Khalil ◽  
Nada Baobaid ◽  
Kamran Khan ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Forced Convection ◽  
Heat Transfer Performance ◽  
Convection Heat Transfer ◽  
Heat Sinks ◽  
Cfd Modeling ◽  
Transfer Performance ◽  
Convection Heat ◽  
Performance Study

Abstract In this work, we extend our heat transfer performance study on our proposed new and novel 3D printable architected heat sinks with geometrically complex structures based on triply periodic minimal surfaces (TPMS). Computational fluid dynamics (CFD) modeling is used to assess the effect of porosity distribution, heat load, and isothermal boundary condition on the performance of the proposed TPMS-based heat sinks in active cooling using natural and forced convection heat transfer environments. The convection heat transfer coefficient, surface temperature, pressure drop are predicted using CFD method. The CFD model is validated using experimental results for the pressure drop and is verified by standard analytical results. Three TPMS structures are investigated in different orientations. Dimensionless heat transfer groups are developed to globalize the heat transfer performance of the proposed heat sinks.

Experimental Study of Internal Forced Convection of Ferrofluid Flow in Porous Media

2014 ◽  
Vol 348 ◽  
pp. 139-146 ◽  
Author(s):  
Ashkan Sehat ◽  
Hani Sadrhosseini ◽  
M. Behshad Shafii
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Experimental Study ◽  
Porous Media ◽  
Temperature Distribution ◽  
Pressure Drop ◽  
Forced Convection ◽  
Volume Fraction ◽  
Flow In Porous Media ◽  
Tetra Methyl Ammonium Hydroxide

This work presents an experimental study of the effect of a magnetic field on laminar forced convection of a ferrofluid flowing in a tube filled with permeable material. The walls of the tube are subjected to a uniform heat flux and the permeable bed consists of uniform spheres of 3-mm diameter. The ferrofluid synthesis is based on reacting iron (II) and iron (III) in an aqueous ammonia solution to form magnetite, Fe3O4. The magnetite is mixed with aqueous tetra methyl ammonium hydroxide, (CH3)4NOH, solution. The dependency of the pressure drop on the volume fraction, and comparison of the pressure drop and the temperature distribution of the tube wall is studied. Also comparison of the wall temperature distribution, convection heat transfer coefficient and the Nusselt numbers of ferrofluids with different volume fractions is investigated for various Reynolds numbers (147 < Re < 205 ). It is observed that the heat transfer is enhanced by using a porous media, increasing the volume fraction had a similar effect. The pressure coefficient decreases for higher Reynolds number. The effect of magnetic field in four strategies, named modes, on ferrofluid flow through the porous media is presented.

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