Stability and photo-thermal conversion performance of binary nanofluids for solar absorption refrigeration systems

The photo-thermal conversion characteristics of a long-term stable binary nanofluid (nanoparticles in 50 wt% lithium bromide-50 wt% water) were investigated in this work. The stability of the binary nanofluid against the agglomeration and sedimentation process was evaluated by a high-speed centrifuge analyzer and transmission electron microscopy. The photo thermal conversion efficiency of the nanofluid was also studied using a solar simulator. Experimental results indicated that the use of the binary nanofluid could significantly increase the light trapping efficiency and, therefore, the bulk temperature, which in turn could increase the evaporation rate due to surface localized heat generation. The experimental results showed the increase of 4.2 and 4.9 percent solar radiative energy in the form of sensible heat after addition of 64 and 321 mg/l iron oxide NPs to the pure water, respectively. The increasing percent is 4.9% and 11.9% for latent heat efficiency in the presence of 64 and 321 mg/l iron oxide NPs, respectively. Possessing both high stability and excellent photo-thermal conversion rate, rod shape iron oxide nanoparticles is suggested to be a potential candidate used for the solar absorption refrigeration systems

Origin of life from a maker's perspective -- focus on protocellular compartments in bottom-up synthetic biology

The origin of life is shrouded in mystery, with few surviving clues, obscured by evolutionary competition. Previous reviews have touched on the complementary approaches of top-down and bottom-up synthetic biology to augment our understanding of living systems. Here we point out the synergies between these fields, especially between bottom-up synthetic biology and origin of life research. We explore recent progress made in artificial cell compartmentation in line with the crowded cell, its metabolism, as well as cycles of growth and division, and how those efforts are starting to be combined. Though the complexity of current life is among its most striking characteristics, none of life's essential features require it, and they are unlikely to have emerged thus complex from the beginning. Rather than recovering the one true origin lost in time, current research converges towards reproducing the emergence of minimal life, by teasing out how complexity and evolution may arise from a set of essential components.Comment: 29 pages, 2 figures, 1 tabl

Synthesis of Stable Iron Oxide Nanoparticle Dispersions in High Ionic Medi

A novel one-pot method was developed in this work to synthesize and disperse nanoparticles in a binary base fluid. As an example, stable magnetite iron oxide (Fe3O4) dispersions, i.e., nanofluids, were produced in a high ionic media of binary lithium bromide-water using a microemulsion-mediated method. The effects of temperature and precursor concentration on morphology and size distribution of produced nanoparticles were evaluated. An effective steric repulsion force was provided by the surface functionalization of nanoparticles during the phase transfer, supported by the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. The formed nanoparticles exhibited a superior stability against agglomeration in the presence of high concentrations of lithium bromide, i.e., from 20 to 50 wt.%, which make them good candidates for a range of novel applications

A review of current techniques for the evaluation of powder mixing

Blending a mixture of powders to a homogeneous system is a crucial step in many manufacturing processes. To achieve a high quality of the end product, powder mixtures should be made with high content uniformity. For instance, producing uniform tablets depends on the homogeneous dispersion of active pharmaceutical ingredient (API), often in low level quantities, into excipients. To control the uniformity of a powder mixture, the first required step is to estimate the powder content information during blending. There are several powder homogeneity evaluation techniques which differ in accuracy, fundamental basis, cost and operating conditions. In this article, emerging techniques for the analysis of powder content and powder blend uniformity, are explained and compared. The advantages and drawbacks of all the techniques are reviewed to help the readers to select the appropriate equipment for the powder mixing evaluation. In addition, the paper highlights the recent innovative on-line measurement techniques used for the non-invasive evaluation of the mixing performance

Study of effective parameters in silver nanoparticle synthesis through method of reverse microemulsion

The present study investigates the synthesis of silver nanoparticles through the method of reverse emulsions using the precursor of AgNO3 and the reduction agent of hydrazine. The influence of several surfactants with different Hydrophile–Lipophile Balance (HLB) on the size distribution and morphology of synthesized nanoparticles was also studied. The nonionic surfactants of Span 80 and PEG 1000, the anionic surfactant of sodium dodecyl sulfate, and the cationic surfactant of cetyl-trimethyl ammonium bromide were examined. The produced silver nanoparticles were characterized using methods of transmission electron microscopy, scanning electron microscopy, X-ray diffraction, UV–vis spectropho- tometry, X-ray photoelectron spectroscopy and laser scattering analyzer

EXPERIMENTAL STUDY OF LAMINAR CONVECTIVE HEAT TRANSFER AND PRESSURE DROP OF CUPROUS OXIDE/ WATER NANOFLUID INSIDE A CIRCULAR TUBE

Laminar convective heat transfer enhancement of cuprous oxide (Cu2O)/water nanofluid flowing through a circular tube was investigated experimentally in the present work. A continuous closed loop was designed to measure heat transfer coefficients and pressure drop associated with the flow of Cu2O/water nanofluid over a wide range of laminar flow conditions. Comparison of the nanofluid experimental results with those of pure water have shown significant enhancement for heat transfer coefficients. On average, a 10% increase in heat transfer coefficient was observed with 16% penalty in pressure drop

A core-shell SO4/Mg-Al-Fe3O4 catalyst for biodiesel production

Catalytic transesterification of triglycerides and esterification of free fatty acids underpins sustainable biodiesel production, wherein efficient heterogeneous catalysts are sought to replace mineral acids. A robust, magnetic core-shell SO4/Mg-Al-Fe3O4 catalyst was synthesised by stepwise co-precipitation, encapsulation, and surface functionalisation. The resulting magnetically-separable catalyst has a surface area of 123 m2 g-1, uniform 6.5 nm mesopores, and a high total acid site loading of 2.35 mmol g-1. Optimum conditions for the (trans)esterification of waste cooking oil (WCO) over the sulfated solid acid catalyst were 95 °C, a methanol:WCO molar ratio of 9:1, and 300 min reaction to achieve 98.5 % FAME yield. Esterification of oleic acid to methyl oleate resulted in an 88 % yield after 150 min under the same reaction conditions. The magnetic solid acid catalyst exhibited good thermal and chemical stability and enabled facile catalyst separation post-reaction and the production of high quality biodiesel

Nanoparticle Formation in Stable Microemulsions for Enhanced Oil Recovery Application

Magnetic iron oxide and titanium dioxide nanoparticles (NPs) have been synthesized inside stable oil-in-water microemulsions in harsh environment of high temperature-high salinity (HT-HS). Screening of anionic–nonionic mixture of commercial surfactants was carried out to identify the appropriate compositions for the production of stable microemulsions in harsh environment. The effects of salinity and NPs formation on interfacial tension and rheological properties of microemulsions were evaluated and compared with other studies. It was found that oil-in-water microemulsions exhibit a non-Newtonian behavior in the absence of NPs, while the surfactant solutions show Newtonian behavior. The shear-thinning characteristic of microemulsions was improved and the interfacial tension between microemulsions and oil phase was increased after generation of NPs. A set of flooding experiments were accomplished using a microfluidic device to assess the efficiency of enhanced oil recovery on the pore scale in the absence and presence of NPs. The flooding tests confirmed the improvement of oil recovery efficiency after the formation of NPs inside the microemulsions. The oil displacement of API flooding was equal to 69.8% and the maximum oil displacement of 76.9% was observed after the injection of microemulsion containing iron oxide NPs