Thermophysical Properties and Pool Boiling Characteristics of Water in Polyalphaolefin Nanoemulsion Fluids

2012 ◽  
Author(s):  
Jiajun Xu ◽  
Bao Yang
Keyword(s):  
Thermal Conductivity ◽  
Thermophysical Properties ◽  
Dynamic Viscosity ◽  
Self Assembly ◽  
Pool Boiling ◽  
Water Concentration ◽  
Interesting Phenomenon ◽  
Conductivity Increase ◽  
Thermal Conductivity Increase ◽  
Measured Thermal Conductivity

In this work, thermophysical properties and pool boiling characteristics of water-in-polyalphaolefin (PAO) nanoemulsion fluids and their dependence on water concentration have been investigated experimentally. Water-in-PAO nanoemulsion fluids are formed via self-assembly with surfactant sodium sullfosuccinate (AOT). Thermal conductivity of the fluids is found to increase with water concentration, as expected from the Maxwell equation. However, the measured thermal conductivity increase is very moderate, e.g., a 16% increase for 8.6Vol. %. Unlike thermal conductivity, the dynamic viscosity of these nanoemulsion fluids first increases with water concentration, reaches a maximum, and then decreases. This trend could be attributed to the attractive forces among water droplets. The boiling behavior of these nanoemulsion fluids has been altered due to water nanodroplets. Adding water nanodroplets can lower the nanoemulsion’s boiling point compared to the pure PAO. Another interesting phenomenon observed is that pool boiling of nanoemulsion fluids randomly follows two different curves when the water concentration is in the range of 5.3 Vol. % to 7.8 Vol. %. The mechanism underlying this phenomenon is not understood yet, but it may be related to the evolution of microstructures in the water-in-PAO nanoemulsion fluids.

Thermophysical Properties and Pool Boiling Characteristics of Water-in-Polyalphaolefin Nanoemulsion Fluids

2013 ◽  
Vol 135 (9) ◽  
Author(s):  
Jiajun Xu ◽  
Bao Yang ◽  
Boualem Hammouda
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Thermophysical Properties ◽  
Self Assembly ◽  
Boiling Heat Transfer ◽  
Small Angle Neutron Scattering ◽  
Room Temperature ◽  
Pool Boiling ◽  
Water Concentration ◽  
Interesting Phenomenon

In this work, thermophysical properties, microstructure, and pool boiling characteristics of water-in-polyalphaolefin (PAO) nanoemulsion fluids have been measured in the water concentration range of 0–10.3 vol. %, in order to gain basic data for nanoemulsion boiling. Water-in-PAO nanoemulsion fluids are formed via self-assembly with surfactant: sodium sullfosuccinate (AOT). Thermal conductivity of these fluids is found to increase monotonically with water concentration, as expected from the Maxwell equation. Unlike thermal conductivity, their dynamic viscosity first increases with water concentration, reaches a maximum at 5.3 vol. %, and then decreases. The observed maximum viscosity could be attributed to the attractive forces among water droplets. The microstructures of the water-in-PAO nanoemulsion fluids are measured via the small-angle neutron scattering (SANS) technique, which shows a transition from sphere to elongated cylinder when the water concentration increases above 5.3 vol. %. The pool boiling heat transfer of these water-in-PAO nanoemulsion fluids is measured on a horizontal Pt wire at room temperature (25 °C, subcooled condition). One interesting phenomenon observed is that the pool boiling follows two different curves randomly when the water concentration is in the range of 5.3 vol. % to 7.8 vol. %.

scholarly journals 19-Fold thermal conductivity increase of carbon nanotube bundles toward high-end thermal design applications

Carbon ◽  
2018 ◽  
Vol 139 ◽  
pp. 445-458 ◽  
Author(s):  
Yangsu Xie ◽  
Tianyu Wang ◽  
Bowen Zhu ◽  
Chaoyi Yan ◽  
Peixin Zhang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotube ◽  
Thermal Design ◽  
Nanotube Bundles ◽  
Conductivity Increase ◽  
Thermal Conductivity Increase

Thermal Properties of Soil Samples from Coastal Sand Landform in Ilaje Local Government Area of Ondo State, Nigeria

2016 ◽  
pp. 4137-4140
Author(s):  
Oluyamo S. S. ◽  
Famutimi O. F. ◽  
Mathew Adekoya ◽  
Aramide T. M.
Keyword(s):  
Thermal Conductivity ◽  
Local Government ◽  
Soil Samples ◽  
Local Government Area ◽  
Particle Sizes ◽  
Root Crops ◽  
Conductivity Increase ◽  
Thermal Conductivity Increase ◽  
Ondo State ◽  
Properties Of Soil

This study examines the thermal conductivity of some selected soil samples from coastal sandlandform inIlaje local government area of Ondo State, Nigeria. The soil samples were sieved into different particle sizes; 300 , 425 , 600 , 850 , and 1180  with appropriate mesh and moulded in form of a Lee’s disc. The thermal conductivity of the samples was determined using parallel plate method. The value of the thermal conductivity increase as the moisture content increaseand decrease with increase in particle sizes for the soil samples. The values of the thermal conductivity obtained   rangedbetween 0.3444  and1.8894 . It was noted that the conductivity of the landforms conforms to the range of conductivities of soil required for some specific crops such as maize, cowpea, pineapple, okro and root crops. The results in the research would be useful to soil/building and soil scientists as well as modern mechanized farmers in determined  appropriate land forms for agricultural and structural purposes.

scholarly journals Enhancement of heat transfer coefficient multi-metallic nanofluid with ANFIS modeling for thermophysical properties

2015 ◽  
Vol 19 (5) ◽  
pp. 1613-1620 ◽  
Author(s):  
Hyder Balla ◽  
Shahrir Abdullah ◽  
Wan Faizal ◽  
Rozli Zulkifli ◽  
Kamaruzaman Sopian
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Thermophysical Properties ◽  
Dynamic Viscosity ◽  
Base Fluid ◽  
Volume Fractions ◽  
The Heat Transfer Coefficient ◽  
Cu And Zn

Cu and Zn-water nanofluid is a suspension of the Cu and Zn nanoparticles with the size 50 nm in the water base fluid for different volume fractions to enhance its Thermophysical properties. The determination and measuring the enhancement of Thermophysical properties depends on many limitations. Nanoparticles were suspended in a base fluid to prepare a nanofluid. A coated transient hot wire apparatus was calibrated after the building of the all systems. The vibro-viscometer was used to measure the dynamic viscosity. The measured dynamic viscosity and thermal conductivity with all parameters affected on the measurements such as base fluids thermal conductivity, volume factions, and the temperatures of the base fluid were used as input to the Artificial Neural Fuzzy inference system to modeling both dynamic viscosity and thermal conductivity of the nanofluids. Then, the ANFIS modeling equations were used to calculate the enhancement in heat transfer coefficient using CFD software. The heat transfer coefficient was determined for flowing flow in a circular pipe at constant heat flux. It was found that the thermal conductivity of the nanofluid was highly affected by the volume fraction of nanoparticles. A comparison of the thermal conductivity ratio for different volume fractions was undertaken. The heat transfer coefficient of nanofluid was found to be higher than its base fluid. Comparisons of convective heat transfer coefficients for Cu and Zn nanofluids with the other correlation for the nanofluids heat transfer enhancement are presented. Moreover, the flow demonstrates anomalous enhancement in heat transfer nanofluids.

scholarly journals SINGLE-PHASE AND TWO-PHASE SECONDARY COOLANTS: SIMULATION AND EVALUATION OF THEIR THERMOPHYSICAL PROPERTIES

2011 ◽  
Vol 4 ◽  
pp. 91
Author(s):  
Pedro Samuel Gomes Medeiros ◽  
Cleiton Rubens Formiga Barbosa ◽  
Francisco De Assis Oliveira Fontes
Keyword(s):  
Thermal Conductivity ◽  
Thermophysical Properties ◽  
Dynamic Viscosity ◽  
Single Phase ◽  
Thermal Storage ◽  
Heat Transfer Fluid ◽  
Viscosity Data ◽  
Ice Slurry ◽  
Two Phase ◽  
Cooling Systems

This paper makes a comparative analysis of the thermophysical properties of ice slurry with conventional single-phase secondary fluids used in thermal storage cooling systems. The ice slurry is a two-phase fluid consisting of water, antifreeze and ice crystals. It is a new technology that has shown great energy potential. In addition to transporting energy as a heat transfer fluid, it has thermal storage properties due to the presence of ice, storing coolness by latent heat of fusion. The single-phase fluids analyzed are water-NaCl and water-propylene glycol solutions, which also operate as carrier fluids in ice slurry. The presence of ice changes the thermophysical properties of aqueous solutions and a number of these properties were determined: density, thermal conductivity and dynamic viscosity. Data were obtained by software simulation. The results show that the presence of 10% by weight of ice provides a significant increase in thermal conductivity and dynamic viscosity, without causing changes in density. The rheological behavior of ice slurries, associated with its high viscosity, requires higher pumping power; however, this was not significant because higher thermal conductivity allows a lower mass flow rate without the use of larger pumps. Thus, the ice slurry ensures its high potential as a secondary fluid in thermal storage cooling systems, proving to be more efficient than single-phase secondary fluids.

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