On the modeling and simulation of coupled adsorption and thermosolutal convection in supercritical carbon dioxide

In this paper, we present a numerical study along with an exhaustive adsorption investigation in a binary dilute mixture model nearby the solvent’s critical point in a configuration relevant for soil remediation. By means of this model, mass and heat transfer efficiency were qualitatively and quantitatively discussed through this work. The convergence of the solution was evaluated on the values of the Nusselt and Sherwood numbers. The results reveal intense convection expanding into the cavity close to the critical point, thus enabling homogeneous adsorption of the solute. Moreover, the mass fraction perturbation isolines exhibit the existence, along the adsorbent plate, of a thin boundary layer which becomes thinner when approaching the critical point.

Kajian Karakteristik Beton Memadat Sendiri yang Menggunakan Serat Ijuk (Hal. 54-65)

ABSTRAKKajian karakteristik beton memadat sendiri yang menggunakan serat ijuk merupakan sebuah kajian yang dilakukan untuk mengetahui pengaruh penambahan serat ijuk terhadap karakteristik beton memadat sendiri (SCC). Beton memadat sendiri yang menggunakan serat ijuk (PFSCC) didesain memiliki campuran yang encer, bermutu tinggi (= 40 MPa) dan memiliki persentase kekuatan lentur yang lebih baik. PFSCC didapatkan dari hasil pencampuran antara semen sebanyak 85%, fly ash 15%, superplastizicer 1,5%, serat ijuk 0%, 0,5%; 1%; 1,5%; 2% dan 3% dari berat binder (semen + fly ash), kadar air 190 kg/m3, agregat kasar 552,47 kg/m3 dan pasir 1.063 kg/m3. Semakin banyak persentase penambahan serat ijuk ke dalam campuran berdampak terhadap menurunnya workability beton segar. Penambahan serat ijuk yang paling baik adalah sebanyak 1%, penambahan tersebut dapat meningkatkan kekuatan tekan beton sebesar 13% dan lentur sebesar 1,8%.Kata kunci: beton memadat sendiri (SCC), beton berserat, beton memadat sendiri yang menggunakan serat ijuk (PFSCC), serat ijuk ABSTRACTThe study of characteristics self compacting concrete using palm fibers is a study conducted to determine the effect of adding palm fibers to characteristics of self compacting concrete (SCC). palm fibers self compacting concrete (PFSCC) is designed to have a dilute mixture, high strength (= 40 MPa), and have better precentage flexural strength. PFSCC was obtained from mixing of 85% cement, 15% fly ash, 1.5% superplastizicer, 0%, 0.5%, 1%, 1.5%, 2% and 3% palm fibers from the weight of binder (cement + fly ash), water content 190 kg/m3, coarse aggregate 552.47 kg/m3 and sand 1,063 kg/m3. The more persentage palm fibers content added to the mixture makes workability of fresh concrete decreases. The best addition of palm fiber is 1%, this addition can increases the compressive strength 13% and flexural strength 1.8%.Keywords: self compacting concrete (SCC), fiber concrete, Palm fiber self compacting concrete (PFSCC), palm fiber

H3P⋯AgI: generation by laser-ablation and characterization by rotational spectroscopy and ab initio calculations

The new compound H3P⋯AgI has been synthesized in the gas phase by means of the reaction of laser-ablated silver metal with a pulse of gas consisting of a dilute mixture of ICF3 and PH3 in argon.

Distortions of ethyne when complexed with a cuprous or argentous halide: the rotational spectrum of C2H2⋯CuF

A new molecule C2H2⋯CuF has been synthesized in the gas phase by means of the reaction of laser-ablated metallic copper with a pulse of gas consisting of a dilute mixture of ethyne and sulfur hexafluoride in argon.

End-of-Injection Behavior of Diesel Sprays Measured With X-Ray Radiography

The behavior of diesel fuel sprays at the end of injection is poorly understood, yet has important implications regarding diesel engine emissions. Recent research has shown that at the end of injection, an entrainment wave is created, causing the fuel spray to rapidly entrain ambient gas. This rapid entrainment creates a dilute mixture of fuel that may be a source of unburned fuel emissions. In this study, X-ray radiography is used to quantitatively probe the fuel mass distribution in diesel sprays at the end of injection. Analysis of the spray velocity at steady-state suggests an entrainment wave speed of several hundred m/s, which is supported by the appearance of a traveling entrainment wave at low ambient density. The spray density declines most rapidly near the nozzle, a behavior that matches the expected entrainment wave behavior. The dilution of the spray plume is most prominent in the central dense region of the spray. Three-dimensional reconstructions of the spray density at the end of injection show that the spray plume considerably widens, enhancing the dilution caused by the reduction in fuel flow.

Multi-Dimensional Simulation on the Matching of Combustion Chamber and Injection Pressure for a Heavy-Duty Diesel Engine

Multi-dimensional simulation was applied for the investigation of the combustion system of a heavy-duty diesel engine. Firstly, the matching of combustion chamber and injection pressure has been determined by simulation. Then through intermediate characteristic parameters which could quantitatively describe the properties of the mixing and combustion, the influence of the matching of chamber caliber ratios and injection pressure on each sub-process in compression and power stroke was analyzed comprehensively. The results showed that, for the model studied in this article, increasing the combustion chamber caliber ratio and injection pressure could help expanding the distribution range of the mixture in cylinder, making the mixture more uniform, increasing the proportion of the dilute mixture, thus effectively improved the power performance.