Keywords : nanofluids

Interfacial layer effect on specific heat of colloidal suspensions

Gaganpreet Chadha; Sunita Srivastava

Advanced Materials Letters, 2017, Volume 8, Issue 5, Pages 645-649
DOI: 10.5185/amlett.2017.6378

A theoretical model for the specific heat of nanofluids containing oxide-based nanoparticles of different sizes and at different temperatures has been presented. The model proposed by Xuan and Roetzel has been modified by incorporating the effect of semi-solid interfacial layer, which is formed due to adsorption of base fluid molecules on the surface of nanoparticles. The contribution of this layer has been taken into account by assuming that the heat capacity, as well as the density of interfacial layer, lies between the corresponding values for the nanoparticle and the fluid and as such these have been estimated by taking the arithmetic and the geometric means of the relevant quantities. It is observed that the specific heat capacity of the nanofluid decreases with increase in particle volume fraction and that the presence of interfacial layer enhances the value even though its thickness has been taken to be only 1-2 nm as estimated by Xue et al. using molecular dynamics simulation. The effects of interfacial layer thickness, nanoparticle size, volume fraction, and specific heat ratio of particle to fluid have been discussed. The obtained results are in good agreement with some recent available experimental data.

Investigation On The Combustion Characteristics Of Alumina Nanoparticles Dispersed Longer Term stable Biodiesel Nanofluids  

D. Srinivas Rao;Raj Kishora Dash

Advanced Materials Letters, 2016, Volume 7, Issue 3, Pages 221-225
DOI: 10.5185/amlett.2016.6152

In this paper, the combustion characteristics of alumina nanoparticles dispersed jatropha biodiesel based nanofluids were investigated by dispersing the alumina nanoparticles having average size of ~13 nm in jatropha biodiesel with 0.1 volume fraction. Only longer duration having more than one year stable nanofluids were tested for the combustion characteristics such as evaporation time on a hot-plate test in the temperature range of 300 0 C to 600 0 C. The preliminary evaporation test results  revealed that the evaporation time of one year older stable ~13 nm alumina nanoparticles dispersed nanofluids significantly improved and were comparable to that of the commercially available diesel fuel beyond 450 0 C. Such type of biofuel based nanofluids having longer term stability and improved combustion characteristics can be utilized directly as an alternate fuel for the future diesel engines. 

Fabrication Of High Stable Gold Nanofluid By Pulsed Laser Ablation In Liquids

R. Torres-Mendieta; R. Mondrag

Advanced Materials Letters, 2015, Volume 6, Issue 12, Pages 1037-1042
DOI: 10.5185/amlett.2015.6038

Laser ablation in liquids by femtosecond radiation has been used to generate gold nanoparticles in a heat transfer fluid to produce a high stable thermal nanofluid as a heat transfer intensification technique. In oil based fluids, no matter the actual fabrication route, nanoparticles tend to agglomerate. Here, we report a new form to control its stability through the addition of a surfactant that does not degrade at high temperatures. It allow us to produce gold nanoparticles of 58±31 nm in the liquid in situ, avoiding in this way the generation of pollution and reducing the maximum point of nanoparticle agglomeration at 370 nm. The developing of this new nanofluid represents a great opportunity for the harvesting of solar energy industry.

Effect Of Nanomaterials Sizes On The Dispersion Stability Of Biodiesel Based Nanofluids

D. Srinivas Rao; Raj Kishora Dash

Advanced Materials Letters, 2015, Volume 6, Issue 3, Pages 247-251
DOI: 10.5185/amlett.2015.5638

The effect average alumina nanoparticle sizes on the long term dispersion stability of biodiesel based nanofluids was investigated. Alumina nanoparticles having two different average sizes (~13nm and ~28nm) were dispersed in the Jatropha biodiesel as the base fluids. The effect of alumina (Al2O3) nanoparticles sizes on the stability of nanofluids was investigated to achieve more stable nanoparticles dispersed nanofluids having longer duration for potential use in alternative fuel energy applications. Different volume fractions (VF) such as 0.1%, 0.2%, 0.3%, 0.4%, and 0.5% nanofluids were prepared by using two different sizes of alumina nanoparticles (~13nm and ~28nm) by using the surfactants Span 80 and Tween 80 in the ratio of 1:1. The results revealed that the nanofluids having the smaller average sizes alumina nanoparticles and 0.1% volume fraction were stable for more than one year as compared to the larger (two times) size nanoparticles having same 0.1% volume fraction. Such long term stable biodiesel based nanofluids can be used as the alternative fuel energy for future automobiles and transportation sectors due to the fuel properties of such nanoparticles dispersed nanofluids retaining the commercial diesel properties.