Effective Viscosity Measurement of CuO and ZnO Nanofluids

2009 ◽  
Author(s):  
Dale A. McCants ◽  
M. Yakut Ali ◽  
Jamil Khan
Keyword(s):  
Heat Transfer ◽  
Effective Viscosity ◽  
Heat Transfer Performance ◽  
Volume Concentration ◽  
Theoretical Models ◽  
Experimental Results ◽  
Transfer Performance ◽  
Increase With Increase ◽  
Zno Nanofluids ◽  
Thermo Physical Properties

Nanofluid has the promising potential for enhancing the heat transfer performance of conventional fluids. Several experimental and numerical attempts have been made earlier to investigate its important thermo physical properties like thermal conductivity and viscosity. The findings and results are quite disperse instead of reaching a definitive agreement. This paper presents effective viscosity measurements of CuO and ZnO nanofluids experimentally. A Brookfield viscometer model DV-I Prime with a CPE 40 cone has been used to determine the effective viscosity of nanofluids. The measurements have included the effect of volume concentration of nanoparticles and temperature. The experimental results are compared with several experimental and theoretical models available in the existing literature. From the obtained experimental results it can be concluded that the viscosity values of the above mentioned nanofluids has a tendency to increase with increase of nanoparticle concentration and follows a decreasing trend with an increase in temperature. Presented results can be used to define the above mentioned nanofluids within the experimental volume concentration range in CFD software package and hence to predict overall heat transfer performance using these nanofluids.

Heat Transfer Performance of Different Nanofluids Flows in a Helically Coiled Heat Exchanger

2013 ◽  
Vol 832 ◽  
pp. 160-165 ◽  
Author(s):  
Mohammad Alam Khairul ◽  
Rahman Saidur ◽  
Altab Hossain ◽  
Mohammad Abdul Alim ◽  
Islam Mohammed Mahbubul
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Friction Factor ◽  
Heat Exchangers ◽  
Heat Transfer Performance ◽  
Volume Concentration ◽  
Transfer Performance

Helically coiled heat exchangers are globally used in various industrial applications for their high heat transfer performance and compact size. Nanofluids can provide excellent thermal performance of this type of heat exchangers. In the present study, the effect of different nanofluids on the heat transfer performance in a helically coiled heat exchanger is examined. Four different types of nanofluids CuO/water, Al2O3/water, SiO2/water, and ZnO/water with volume fractions 1 vol.% to 4 vol.% was used throughout this analysis and volume flow rate was remained constant at 3 LPM. Results show that the heat transfer coefficient is high for higher particle volume concentration of CuO/water, Al2O3/water and ZnO/water nanofluids, while the values of the friction factor and pressure drop significantly increase with the increase of nanoparticle volume concentration. On the contrary, low heat transfer coefficient was found in higher concentration of SiO2/water nanofluids. The highest enhancement of heat transfer coefficient and lowest friction factor occurred for CuO/water nanofluids among the four nanofluids. However, highest friction factor and lowest heat transfer coefficient were found for SiO2/water nanofluids. The results reveal that, CuO/water nanofluids indicate significant heat transfer performance for helically coiled heat exchanger systems though this nanofluids exhibits higher pressure drop.

An Evaluation of the Application of Nanofluids in Intercooled Cycle Marine Gas Turbine Intercooler

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Ningbo Zhao ◽  
Xueyou Wen ◽  
Shuying Li
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Gas Turbine ◽  
Heat Transfer Performance ◽  
Volume Concentration ◽  
Inlet Temperature ◽  
Transfer Performance ◽  
Pumping Power ◽  
Flow And Heat Transfer ◽  
Overall Performance

Coolant is one of the important factors affecting the overall performance of the intercooler for the intercooled (IC) cycle marine gas turbine. Conventional coolants, such as water and ethylene glycol, have lower thermal conductivity which can hinder the development of highly effective compact intercooler. Nanofluids that consist of nanoparticles and base fluids have superior properties like extensively higher thermal conductivity and heat transfer performance compared to those of base fluids. This paper focuses on the application of two different water-based nanofluids containing aluminum oxide (Al2O3) and copper (Cu) nanoparticles in IC cycle marine gas turbine intercooler. The effectiveness-number of transfer unit method is used to evaluate the flow and heat transfer performance of intercooler, and the thermophysical properties of nanofluids are obtained from literature. Then, the effects of some important parameters, such as nanoparticle volume concentration, coolant Reynolds number, coolant inlet temperature, and gas side operating parameters on the flow and heat transfer performance of intercooler, are discussed in detail. The results demonstrate that nanofluids have excellent heat transfer performance and need lower pumping power in comparison with base fluids under different gas turbine operating conditions. Under the same heat transfer, Cu–water nanofluids can reduce more pumping power than Al2O3–water nanofluids. It is also concluded that the overall performance of intercooler can be enhanced when increasing the nanoparticle volume concentration and coolant Reynolds number and decreasing the coolant inlet temperature.

Experimental Investigation of Oscillating Heat Pipe With Hybrid Fluids of Liquid Metal and Water

2019 ◽  
Vol 141 (7) ◽  
Author(s):  
Tingting Hao ◽  
Hongbin Ma ◽  
Xuehu Ma
Keyword(s):  
Heat Transfer ◽  
Liquid Metal ◽  
Heat Pipe ◽  
Heat Input ◽  
Heat Transfer Performance ◽  
Pure Water ◽  
Experimental Results ◽  
Working Fluid ◽  
Transfer Performance ◽  
Oscillating Heat Pipe

A new oscillating heat pipe (OHP) charged with hybrid fluids can improve thermal performance. The key difference in this OHP is that it uses room temperature liquid metal (Galinstan consisting of gallium, indium, and tin) and water as the working fluid. The OHP was fabricated on a copper plate with six turns and a 3 × 3 mm2 cross section. The OHP with hybrid fluids as the working fluid was investigated through visual observation and thermal measurement. Liquid metal was successfully driven to flow through the OHP by the pressure difference between the evaporator and the condenser without external force. Experimental results show that while added liquid metal can increase the heat transport capability, liquid metal oscillation amplitude decreases as the filling ratio of liquid metal increases. Visualization of experimental results show that liquid metal oscillation position and velocity increase as the heat input increases. Oscillating motion of liquid metal in the OHP significantly increases the heat transfer performance at high heat input. The lowest thermal resistance of 0.076 °C/W was achieved in the hybrid fluids-filled OHP with a heat input of 420 W. We experimentally demonstrated a 13% higher heat transfer performance using liquid metal as the working fluid compared to an OHP charged with pure water.

Comparative Analysis of Heat Transfer Characteristics for CO2 and Conventional Refrigerants

2011 ◽  
Vol 130-134 ◽  
pp. 1306-1309
Author(s):  
Jun Lan Yang ◽  
Yi Tai Ma ◽  
Min Xia Li
Keyword(s):  
Heat Transfer ◽  
Liquid Film ◽  
Heat Transfer Performance ◽  
Quantitative Comparison ◽  
Condensation Heat Transfer ◽  
Condensation Process ◽  
Transfer Performance ◽  
Comparison Study ◽  
Cooling Process ◽  
Thermo Physical Properties

s: The obvious characteristics of transcritical CO2 cycle are that the heat rejection process takes place in the supercritical region (about 8-12Mpa). The heat transfer features of CO2 under supercritical pressure are different from those of the conventional refrigerants. And the heat transfer performances comparison study for supercritical CO2 fluid and the conventional refrigerants are carried out by means of thermo-physical properties analog analysis and experimental results quantitative comparison. The special properties variation of supercritical CO2 fluid makes its heat transfer performance different from the conventional fluids. From the view of properties analysis and quantitative comparison, the heat transfer performance of supercritical CO2 is equivalent to the condensation heat transfer of conventional refrigerants. Although the condensation coefficient is very large since there is phase change and latent heat variation in the condensation process, there is liquid film thermal resistance. While in the supercritical CO2 cooling process, there is no liquid film in existence and the thickness of the boundary layer is very thin. The heat transfer temperature difference is very large, so the heat transfer performance in the supercritical CO2 cooling process is equivalent to that of the condensation heat transfer.

Heat Transfer Performance During Condensation Inside Spiralled Micro-Fin Tubes

2004 ◽  
Vol 126 (3) ◽  
pp. 321-328 ◽  
Author(s):  
Jean-Pierre M. Bukasa ◽  
Leon Liebenberg ◽  
Josua P. Meyer
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Performance ◽  
Geometric Parameters ◽  
Experimental Results ◽  
Outer Diameter ◽  
Transfer Performance ◽  
Fin Tube ◽  
R 134A ◽  
Fin Tubes ◽  
Spiral Angle

The effect of the spiral angle on the heat transfer performance in micro-fin tube condensers has not yet been clearly established because other geometric parameters affecting the heat transfer performance were simultaneously varied in previous studies. This paper reports on the influence of the spiral angle on the heat transfer during condensation inside spiralled micro-fin tubes having all other geometric parameters constant. Tests were conducted for condensation of R-22, R-134a, and R-407C inside a smooth (9.52 mm outer diameter) and three micro-fin tubes with approximately the same diameter, having spiral angles of 10 deg, 18 deg, and 37 deg, respectively. Experimental results indicated a heat transfer augmentation with spiral angle increase. A new semi-empirical predictive correlation was developed for practical design of spiralled micro-fin tubes. The proposed new correlation predicted the majority of experimental results of the present study within a deviation zone of ±20%.

Experimental Study on the Thermal Properties and Stability of Hybrid Nanofluids and Evaluation of its Heat Exchange Efficiency

2020 ◽  
Author(s):  
Yubai Xiao ◽  
Hu Zhang ◽  
Junmei Wu
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Transfer Performance ◽  
Volume Concentration ◽  
High Thermal Conductivity ◽  
Transfer Efficiency ◽  
Working Fluid ◽  
Transfer Performance ◽  
Heat Transfer Efficiency ◽  
Hybrid Nanofluids

Abstract In recent years, hybrid nanofluids, as a new kind of working fluid, have been widely studied because they possessing better heat transfer performance than single component nanofluids when prepared with proper constituents and proportions. The application of hybrid nanofluids in nuclear power system as a working fluid is an effective way of improving the capability of In-Vessel Retention (IVR) when the reactor is in a severe accident. In order to obtain hybrid nanofluids with excellent heat transfer performance, three kinds of hybrid nanofluids with high thermal conductivity are measured by transient plane source method, and their viscosity and stability are also investigated experimentally. These experimental results are used to evaluate the heat transfer efficiency of hybrid nanofluids. The results show that: (1) The thermal conductivity of hybrid nanofluids increases with increasing temperature and volume concentration. When compared to the base fluid, the thermal conductivity of Al2O3-CuO/H2O, Al2O3-C/H2O and AlN-TiO2/H2O nanofluids at 0.25% volume concentration increased by 36%, 24%, and 22%, respectively. (2) Surfactants can improve the stability of hybrid nanofluids. The Zeta potential value is related to the thermal conductivity of the hybrid nanofluids, and it could be used to explain the relationship between the thermal conductivity of the hybrid nanofluids and the dispersion. It also could provide a reference for subsequent screening of high thermal conductivity nanofluids. (3) The addition of C/H2O can effectively reduce the dynamic viscosity coefficient of hybrid nanofluids. (4) The analysis of heat transfer efficiency of the hybrid nanofluids found that both Al2O3-CuO/H2O and Al2O3-C/H2O have better heat transfer ability than water under certain mixing conditions. This study is conducive to further optimizing hybrid nanofluids and its application to the In-Vessel Retention in severe reactor accidents.

scholarly journals Experimental Investigation on Pool Boiling Heat Transfer Performance Using Tungsten Oxide WO3 Nanomaterial-Based Water Nanofluids

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1922 ◽  
Author(s):  
Mohammed Saad Kamel ◽  
Ferenc Lezsovits
Keyword(s):  
Heat Transfer ◽  
Tungsten Oxide ◽  
Boiling Heat Transfer ◽  
Heat Transfer Performance ◽  
Volume Concentration ◽  
Pool Boiling ◽  
Deionized Water ◽  
Transfer Performance ◽  
Pool Boiling Heat Transfer ◽  
Boiling Heat Transfer Coefficient

This study aims to experimentally investigate the pool boiling heat transfer coefficient behavior using tungsten oxide-based deionized water nanofluids and comparing them to deionized water as conventional fluid. The influence of different dilute volumetric concentrations (0.005%–0.05% Vol.) and applied heat fluxes were examined to see the effect of these parameters on the pool boiling heat transfer performance using nanofluids from a typical horizontal heated copper tube at atmospheric pressure conditions. Results demonstrated that the pool boiling heat transfer coefficient (PBHTC) for both deionized water and nanofluids increased with increasing the applied heat flux. The higher PBHTC enhancement ratio was 6.7% for a volume concentration of 0.01% Vol. at a low heat flux compared to the deionized water case. Moreover, the PBHTC for nanofluids was degraded compared to the deionized water case, and the maximum reduction ratio was about 15% for a volume concentration of 0.05% Vol. relative to the baseline case. The reduction in PBHTC was attributed to the deposition of tungsten oxide nanoflakes on the heating surface during the boiling process, which led to a decrease in the density of the nucleation sites.

Investigation of Regenerator Matrix Through Figure of Merit Analysis

2015 ◽  
Author(s):  
Ramla Gheith ◽  
Fethi Aloui ◽  
Sassi Ben Nasrallah
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Figure Of Merit ◽  
Heat Transfer Performance ◽  
Optimal Operation ◽  
Stirling Engine ◽  
Experimental Results ◽  
Transfer Performance ◽  
Metallic Wire ◽  
Operation Parameters

To choose the adequate regenerator, that gives the highest Stirling engine performances, different compromises must be considered. The figure of Merits is a powerful tool to evaluate and compare the performance of different Stirling engine regenerator matrices. The figure of merits is usually defined as the ratio between the heat transfer performance and the pressure drop losses through the regenerator matrix. The figure of merits can be obtained too by calculating different rations of pressure drop ΔPPm of regenerator volume VdrVE and for regenerator loss Q.tQ.r F M S C = 1 Δ P P m V d r V E Q . t Q . r In this study the experimental results of various Gamma Stirling engine metallic wire regenerator matrices are presented. The figure of merit parameter will be estimated to determine the adequate regenerator. Then the FMSC was used to determine the best regenerator porosity and the optimal operation parameters.

CFD Investigation of Developing and Redeveloping Laminar Flow and Heat Transfer Characteristics in Coiled Tube Systems for Constant Wall Temperature Heating and Cooling: Part I — Toroid and Helical Configurations

2006 ◽  
Author(s):  
Anthony J. Bowman ◽  
Hyunjae Park
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Performance ◽  
Transfer Performance ◽  
Tube Radius ◽  
Coiled Tube ◽  
Cfd Models ◽  
Heating And Cooling ◽  
Flow And Heat Transfer ◽  
Temperature Heating ◽  
Thermo Physical Properties

In this paper developing laminar fluid flow and heat transfer performance in toroidal and helical coiled tube heat exchanger systems with coil-to-tube radius ratios (5 to 45) and small helical pitch are investigated using appropriate numerical modeling techniques available in the CFD package (Fluent v6.2). Base CFD models were primarily developed, optimized and compared with available published friction factor and heat transfer data and correlations for the toroidal and helical coil systems. With the proven CFD modeling technique and the results obtained, the analysis was extended to the coil-to-tube radius ratios of interest and to the investigation of the effect of thermo-physical properties of working fluids on the system thermal performance. The CFD models employ variable thermo-physical properties in the analysis of uniform wall temperature heating and cooling of common working fluids such as air and water. Defining appropriate dimensionless variables to describe the developing and redeveloping hydrodynamic and thermal flow for coiled tube systems, the variations of friction factor and local Nusselt number along the coil are investigated. It has been shown that in addition to the common affecting parameters, i.e. the coil-to-tube radius ratio and the Dean and Prandtl numbers, the heat transfer performance also depends upon the interactions (expansion and suppression) between the viscous and thermal boundary layers due to secondary flows caused by the centrifugal and torsional forces inherent in coiled tube systems. Upon investigation of the variations of the local dimensionless velocity and temperature along the coil length, it was found that for both heating and cooling conditions, fully-developed hydrodynamic and thermal conditions are not established in the coiled-tube system for the geometric constraints and system boundary and operating conditions used in this work. The case studies performed in this paper indicated approximately 20-30% higher for heating of water (20-30% lower for cooling of air and water) than values of heat transfer coefficients obtained from the reported correlations. The results obtained in this work can be used to correct/adjust the flow and thermal performance used in the design of toroidal and helical coiled tube systems.

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