Effect of Volume Fraction of Nanoparticles to the Convective Heat Transfer of Nanofluids

2011 ◽  
Vol 464 ◽  
pp. 528-531 ◽  
Author(s):  
Zhi Yong Ling ◽  
Tao Zou ◽  
Jian Ning Ding ◽  
Guang Gui Cheng ◽  
Peng Fei Fu ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Volume Fraction ◽  
Small Difference ◽  
Numerical Study ◽  
Convective Heat Transfer Coefficient ◽  
Full Development ◽  
Significant Difference

A numerical study on the convective heat transfer characteristics of Cu-water nanofluid under the laminar flow condition was performed. The results show that the convective heat transfer coefficient increases with the increase of the volume fraction of the nanoparticles and the Reynolds number. There is a significant difference between the numerical simulation result and the result calculated from the Shah equation in the entrance region, but a small difference in full development areas. The numerical results agree well with that obtained from the Xuan equation when the Reynolds number and the volume fraction of the nanoparticles are small, but the errors between them increase as the increase of the Reynolds number and the volume fraction of nanoparticles.

scholarly journals CONVECTIVE HEAT TRANSFER AND POWER SAVING APPLICATION OF SI BASED NANOPARTICLES IN A CIRCULAR PIPE

2020 ◽  
Vol 50 (4) ◽  
pp. 321-327
Author(s):  
Md Insiat Islam Rabby ◽  
Farzad Hossain ◽  
S.A.M. Shafwat Amin ◽  
Tazeen Afrin Mumu ◽  
MD Ashraf Hossain Bhuiyan ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Base Fluid ◽  
Volume Fraction ◽  
Numerical Study ◽  
Convective Heat Transfer Coefficient ◽  
Circular Pipe ◽  
Working Fluid ◽  
Pumping Power

A numerical study of laminar forced convection heat transfer for the fully developed region inside a circular pipe filled with Si based nanoparticle is presented for investigating the parameters of heat transfer. Four Si based nanoparticles Si, SiC, SiO2, Si3N4 with 1-5% volume fraction have been mixed with water to prepare nanofluids which is used for working fluid to flow over a circular pipe with 5mm diameter and 700mm length. Heat transfer characteristics and pumping power have been calculated at fully developed region with constant heat flux condition on pipe wall to identify the heat transfer enhancement ratio and pumping power reduction ratio among base fluid water and each nanofluids. It is worth mentioning that utilizing SiC nanoparticle shows not only the highest increment of Nusselt number and convective heat transfer coefficient but also the highest decrement of pumping power requirement and FOM in comparison to the base fluid.

scholarly journals Convective Heat Transfer of Al2O3 and CuO Nanofluids Using Various Mixtures of Water-Ethylene Glycol as Base Fluids

2017 ◽  
Vol 7 (2) ◽  
pp. 1496-1503
Author(s):  
K. Boukerma ◽  
M. Kadja
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Ethylene Glycol ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Thermal Performance ◽  
Volume Fraction ◽  
Numerical Study ◽  
Constant Heat Flux ◽  
Volume Fractions

In this work, a numerical study has been performed on the convective heat transfer of Al2O3/Water-Ethylene Glycol (EG) and CuO/(W-EG) nanofluids flowing through a circular tube with circumferentially non-uniform heating (constant heat flux) under the laminar flow condition. We focus on the study of the effect of EG-water mixtures as base fluids with mass concentration ranging from 0% up to 100% ethylene glycol on forced convection. The effect on the flow and the convective heat transfer behavior of nanoparticle types, their volume fractions (φ=1-5%) and Reynolds number are also investigated. The results obtained show that the highest values of the average heat transfer coefficient is observed between 40% and 50% of EG concentration. The average Nusselt number increases with the increase in EG concentration in the base fluid, and the increase in the Reynolds number and volume fraction. For concentrations of EG above 60%, and for all volume fractions, the increase of thermal performance of nanofluids became inversely proportional to the increase of Reynolds number. In addition, CuO/(W-EG) nanofluids show the best thermal performance compared with Al2O3/ (W-EG) nanofluids.

Experimental Model of Temperature-Driven Nanofluid

2006 ◽  
Vol 129 (6) ◽  
pp. 697-704 ◽  
Author(s):  
A. G. Agwu Nnanna
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Small Volume ◽  
Volume Fraction ◽  
Convective Heat Transfer Coefficient ◽  
Isothermal Condition ◽  
Carrier Fluid ◽  
Small Volume Fraction ◽  
The Impact

This paper presents a systematic experimental method of studying the heat transfer behavior of buoyancy-driven nanofluids. The presence of nanoparticles in buoyancy-driven flows affects the thermophysical properties of the fluid and consequently alters the rate of heat transfer. The focus of this paper is to estimate the range of volume fractions that results in maximum thermal enhancement and the impact of volume fraction on Nusselt number. The test cell for the nanofluid is a two-dimensional rectangular enclosure with differentially heated vertical walls and adiabatic horizontal walls filled with 27 nm Al2O3–H2O nanofluid. Simulations were performed to measure the transient and steady-state thermal response of nanofluid to imposed isothermal condition. The volume fraction is varied between 0% and 8%. It is observed that the trend of the temporal and spatial evolution of temperature profile for the nanofluid mimics that of the carrier fluid. Hence, the behaviors of both fluids are similar. Results shows that for small volume fraction, 0.2⩽ϕ⩽2% the presence of the nanoparticles does not impede the free convective heat transfer, rather it augments the rate of heat transfer. However, for large volume fraction ϕ>2%, the convective heat transfer coefficient declines due to reduction in the Rayleigh number caused by increase in kinematic viscosity. Also, an empirical correlation for Nuϕ as a function of ϕ and Ra has been developed, and it is observed that the nanoparticle enhances heat transfer rate even at a small volume fraction.

scholarly journals CONVECTIVE HEAT TRANSFER CHARACTERISTICS OF AQUEOUS TiO2 NANOFLUID UNDER LAMINAR FLOW CONDITIONS

2008 ◽  
Vol 07 (06) ◽  
pp. 325-331 ◽  
Author(s):  
S. M. SOHEL MURSHED ◽  
KAI CHOONG LEONG ◽  
CHUN YANG ◽  
NAM-TRUNG NGUYEN
Keyword(s):  
Heat Transfer ◽  
Laminar Flow ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Volume Fraction ◽  
Convective Heat Transfer Coefficient ◽  
Transfer Coefficients ◽  
Enhancement Of Heat Transfer ◽  
Heat Transfer Coefficients ◽  
Constant Wall Heat Flux

This paper reports an experimental investigation into force convective heat transfer of nanofluids flowing through a cylindrical minichannel under laminar flow and constant wall heat flux conditions. Sample nanofluids were prepared by dispersing different volumetric concentrations (0.2–0.8%) of nanoparticles in deionized water. The results showed that both the convective heat transfer coefficient and the Nusselt number of the nanofluid increase considerably with the nanoparticle volume fraction as well as the Reynolds number. Along with the enhanced thermal conductivity of nanofluids, the migration, interactions, and Brownian motion of nanoparticles and the resulting disturbance of the boundary layer are responsible for the observed enhancement of heat transfer coefficients of nanofluids.

scholarly journals Determination of Heat Transfer Coefficients Over Ribbed Surfaces With Infrared Thermography

1997 ◽  
Author(s):  
Francisco P. Brójo ◽  
Luís C. Gonçalves ◽  
Pedro D. Silva
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Heat Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Convective Heat Transfer Coefficient ◽  
Stanton Number ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients

The scope of the present work is to characterize the heat transfer between a ribbed surface and an air flow. The convective heat transfer coefficients, the Stanton number and the Nusselt number were calculated in the Reynolds number range, 5.13 × 105 to 1.02 × 106. The tests were performed inside a turbulent wind tunnel with one roughness height (e/Dh = 0.07). The ribs had triangular section with an attack angle of 60°. The surface temperatures were measured using an infrared (IR) thermographic equipment, which allows the measurement of the temperature with a good spatial definition (10.24 × 10−6 m2) and a resolution of 0.1°C. The experimental measures allowed the calculation of the convective heat transfer coefficient, the Stanton number and the Nusselt number. The results obtained suggested a flow pattern that includes both reattachment and recirculation. Low values of the dimensionless Stanton number, i.e. Stx*, are obtained at the recirculation zones and very high values of Stx* at the zones of reattachment. The reattachment is located at a dimensionless distance of 0.38 from the top of the rib. That distance seems to be independent of the Reynolds number. The local dimensionless Stanton number remains constant as the Reynolds number varies. The convective heat transfer coefficient presents an uncertainty in the range of 3 to 6%.

scholarly journals Statistical Analysis of the Effect of Nanoparticles Volume Fraction on Turbulent Forced Convective Heat Transfer Coefficient of Nanofluid in a Circular Tube

2015 ◽  
Vol 37 ◽  
pp. 141
Author(s):  
Farhad Vahidinia ◽  
Behrooz Keshtegar ◽  
Mohadeseh Miri
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Probability Distribution ◽  
Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Volume Fraction ◽  
Circular Tube ◽  
Convective Heat Transfer Coefficient ◽  
Nanoparticles Volume Fraction

In this paper, the statistical analysis of the effect of nanoparticles volume fraction on one of the most important thermal characteristics turbulent flow of nanofluid i.e. convection heat transfer coefficient, inside a circular tube with uniform wall heat flux is investigated numerically. Also, water as a base fluid and Al2O3 as suspended particles with a diameter of 36 nm are considered. Heat transfer characteristics are computed using the solution of elliptic equations based on discrete the finite volume method and the second order upwind. The relationship between pressure and velocity using SIMPLEC algorithm is established. In this study, the variation of volume fraction of nanoparticles is assumed in the range of 0 to 6%. The best probability distribution function of the heat transfer parameters are selected using chi square test that various probability distribution such as: Gamma, Normal, Lognormal, Gumbel, and Frechet are evaluated based on numerical analysis of tube flow. After reviewing the results, it was found that with increasing volume fraction of nanoparticles, the convective heat transfer coefficient increases. On the other hand, the convective heat transfer coefficients with regard to variation of volume fraction of nanoparticles follow Gumbel Max probability distribution function.

scholarly journals NUMERICAL STUDY OF THERMAL CHARACTERISTICS OF FUEL OIL-ALUMINA AND WATER-ALUMINA NANOFLUIDS FLOW IN A CHANNEL IN THE LAMINAR FLOW

2018 ◽  
Vol 19 (1) ◽  
pp. 251-269 ◽  
Author(s):  
Hossein Fatahian ◽  
Hesamoddin Salarian ◽  
Majid Eshagh Nimvari ◽  
Esmaeel Fatahian
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Laminar Flow ◽  
Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Volume Fraction ◽  
Convective Heat Transfer Coefficient ◽  
Fuel Oil ◽  
Alumina Nanofluid

The present study investigated the thermal effects of the use of nanoparticles in the fuel-oil and water-based fluids, as well as the numerical simulation of laminar flow of fuel-oil-alumina and the water-alumina nanofluids in a channel. A second order discretization method was used for solving equations and a SIMPLE algorithm was applied for pressure-velocity coupling using Fluent. Effect of nanoparticle volume fraction and particles size in different Reynolds numbers (900≤Re≤2100) on the convective heat transfer coefficient was studied. The simulation was conducted for three different volume fractions and particle sizes in the laminar flow under constant heat flux. The results showed that adding nanoparticles to the base fluid caused an increase in the thermal conductivity ratio of the fluid, which was observed to a greater degree in the fuel oil-alumina nanofluid than in the water-alumina nanofluid. The increase in nanoparticle volume fraction caused an increase in the convective heat transfer coefficient and the Nusselt number of the nanofluids. The significant point of this study was that in the same volume fraction, the effect of adding alumina nanoparticles to the fuel-oil-based fluid had more effect than adding these particles to water-based fluid, while the effect of increasing the Reynolds number in the water-alumina nanofluid on convective heat transfer coefficient was greater than the fuel-oil-alumina. Also, in the same Reynolds number and volume fraction with increasing size of nanoparticles, the value of the convective heat transfer coefficient was decreased. The results of this study can be used in refineries and petrochemical industries where the fuel-oil fluid flows in the channels. ABSTRAK: Kajian ini adalah bagi mengkaji kesan haba terhadap penggunaan bahan bakar-minyak dan cecair asas-air dalam nanopartikel, juga menjalankan simulasi pengiraan aliran laminar bahan bakar-minyak-alumina dan cecair-nano air-alumina dalam saluran. Kaedah berasingan kelas kedua telah digunakan bagi menyelesaikan persamaan dan algoritma SIMPLE telah diaplikasikan dalam gandingan kelajuan-tekanan menggunakan Fluent. Kesan jumlah pecahan nanopartikel dan pelbagai bilangan saiz zarah dalam bilangan Reynolds (900≤Re≤2100) pada pekali pemindahan haba perolakan telah dikaji. Simulasi telah dijalankan pada tiga pecahan isipadu berlainan dan pada zarah dalam aliran laminar dengan fluks haba tetap. Hasil kajian menunjukkan bahawa dengan penambahan nanopartikel dalam cecair-asas menyebabkan peningkatan nisbah daya pengaliran haba cecair pada cecair-nano bahan bakar-minyak-alumina melebihi daripada cecair-nano air-alumina. Penambahan pada pecahan isipadu nanopartikel ini menyebabkan peningkatan pada nilai pekali pemindahan haba perolakan dan bilangan Nusselt dalam cecair-nano. Perkara penting dalam kajian ini adalah pada pecahan isipadu sama, kesan penambahan nanopartikel alumina kepada cecair berasaskan minyak mempunyai kesan yang lebih besar daripada penambahan zarah-zarah ini kepada cecair berasaskan air. Pada masa sama, kesan peningkatan bilangan Reynolds dalam cecair-nano air-alumina pada pekali pemindahan haba perolakan lebih besar daripada kesan peningkatan bahan bakar-minyak-alumina. Selain itu, pada bilangan Reynolds yang sama dan dengan peningkatan saiz nanopartikel pecahan isipadu, nilai pekali pemindahan haba perolakan turut menurun. Hasil kajian ini boleh digunakan dalam industri penapisan dan petrokimia di mana bahan bakar cecair minyak mengalir dalam saluran.

Numerical Study on the Mechanism of Heat Transfer Enhancement in Fe3O4 Nanoferrofluids With Magnetic Field

2019 ◽  
Author(s):  
Chenfei Wang ◽  
Dongdong Gao ◽  
Minli Bai ◽  
Peng Wang ◽  
Yubai Li
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Fe3o4 Nanoparticles ◽  
Volume Fraction ◽  
Numerical Study ◽  
Transfer Coefficients ◽  
Two Phase ◽  
Enhancement Of Heat Transfer

Abstract Nanofluids is reported to significantly enhance heat transfer but with little cost of pressure loss. To further the enhancement of heat transfer using Fe3O4 nanofluids, a magnetic field is employed to control the trajectory of Fe3O4 nanoparticles. A numerical study is conducted with commercial soft ANSYS FLUENT and the simulations are done with a two-phase flow approach named Euler-Lagrange. By comparing heat transfer of laminar flow in a horizontal tube with magnetic field or not, various volume fraction (0.5%/2%) and Reynolds numbers (Re = 200–1000) are considered. Results show that magnetic field contributes an average 4% promotion in convective heat transfer coefficients compared with the condition of no magnet. The mechanism of the enhancement of heat transfer with magnetic field is explored based on the analysis of velocity field. Fe3O4 Nanoparticles move up and down under the magnetic force, and convective heat transfer is enhanced because of the disturbance of the Fe3O4 nanoparticles. Slip flow between the base fluid and nanoparticles also contributes to the enhancement of heat transfer.

scholarly journals CFD Simulation of Convective Heat Transfer on Vernacular Sustainable Architecture: Validation and Application of Methodology

2019 ◽  
Vol 11 (15) ◽  
pp. 4231
Author(s):  
Wenzhou Zhong ◽  
Tong Zhang ◽  
Tetsuro Tamura
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Reynolds Number ◽  
Flow Field ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Convective Heat Transfer Coefficient ◽  
Vernacular Architecture ◽  
Building Design ◽  
Building Model

The global background of energy shortages and climate deterioration demands bioclimatic sustainable buildings. Vernacular architecture can provide a useful resource of passive strategies and techniques for creating inner comfort conditions with minimum heating, ventilation, and air conditioning (HVAC) assistance. The identification and verification of such knowledge are essential for climate responsive or energy passive building design. Among the methods, computational fluid dynamics (CFD) is a useful tool for simulating convective heat transfer of vernacular architecture and predicting the convective heat transfer coefficient (CHTC) and flow field. Geometric complexity and diversity of building samples are crucial in the development of an effective simulation methodology in terms of computational cost and accuracy. Therefore, this paper presents high-resolution 3D steady Reynolds-averaged Navier–Stokes (RANS) CFD simulations of convective heat transfer on Japanese vernacular architecture, namely, “machiya.” A CFD validation study on the CHTC is performed based on wind-tunnel experiments on a cube heated by constant heat flux and placed in a turbulent channel flow with a Reynolds number of 3.3 × 104. Three steady RANS models and two boundary layer modeling approaches are compared and discussed. Results show that the SST k-ω model applied with low Reynolds number modeling approach is suitable for CHTC simulations on a simplified building model. The RNG k-ε model applied with wall functions is an appropriate choice for simulating flow field of a complicated building model. Overall, this study develops a methodology involving RANS model selection, boundary layer modeling, and target model fitting to predict the convective heat transfer on vernacular architecture.

Sign in / Sign up

Export Citation Format

Share Document