• Energy Research
• Closed Access close
• Restricted close
• Open Source close
• Embargo close
• UA close

Abstract Spectrum down-shifting converters based on Cd-free Zn–Cu–In–S(ZCIS)/ZnS core/shell quantum dots are modeled and simulated for applications in photovoltaics using the Monte-Carlo approach. The set of physical characteristics required for the successful implementation of this type of material in spectral converters have been identified. The advantage of using ZCIS/ZnS quantum dots in such converters is highlighted through a comparison with the conventional CdSe/ZnS quantum dots. The simulation model has been evaluated experimentally using ZCIS/ZnS quantum dots dispersed in polydimethylsiloxane (PDMS) as a spectrally converting top layer. In addition to validating the utility and precision of the simulation, it is shown that the polymerization of polydimethylsiloxane does not significantly impede the photoluminescent quantum yield of the ZCIS/ZnS quantum dots.

Balastless thin-layer MnO2/Al electrodes without an electroconducting carbon additive in combination with multiwalled carbon nanotubes (MWCNT) MnO2/Al-MWCNT, as well as bulk-modified paste electrodes MnO2 (MWCNT) F4/18H12X9T stainless steel electrodes, have been studied in the redox reaction with lithium in a model accumulator on the basis of propylene carbonate (PC), dimetoxiethane (DME), and 1MLiClO4 and ethyl carbonate (EC), dimethylcarbonate (DMC), and 1M LiClO4 electrolytes. The window of the electrochemical stability of the anode oxidation on MnO2-Al/electrodes in the work range of the potentials for the electrolytes under study is 2.0–4.1 and 2.0–4.2 V, respectively. Because of the high contact resistance between the particles of the thin-layer β/γ-MnO2/Al electrode, its discharge capacity cannot exceed 110–120 mA h/g; however, it is stable through 180 cycles. The discharge capacity volume paste MnO2, F4/18H12X9T electrodes during the first cycle reaches 265–280 mA h/g and that of the reversible capacity ranges up to 185–250 mA h/g during the first 50 cycles. The role of the aluminum collector in the electrochemical transformation of MnO2 has been discussed in thin-layer MnO2/Al electrodes obtained by the mechanical rubbing of the active component into the aluminum matrix. The lithium chemical diffusion coefficient DLi established in the redox reaction of MnO2 with lithium has been estimated in thin-layer composite MnO2 MWCNT/Al electrodes at the current peak values (around 10−12 cm2/s) by slow cyclic voltammetry.

This paper describes the absorption process of gaseous ammonia into liquid water in the plate heat exchanger, which is considered to be the crucial part of an absorption cooling system. Two approaches are utilized to numerically simulate this absorption process. In the first approach, the dissolution of gaseous ammonia into liquid water, as well as the following chemical reaction between the dissolved liquid ammonia and liquid water, are modeled. In the second approach, only the dissolution of ammonia into water is considered. The Henry’s Law with Van’t Hoff correlation is used for the simulation of the ammonia absorption process, namely the calculation of the concentration of ammonia in gas and in liquid. The Henry’s law is utilized since its line has the best correlation with the ammonia-water equilibrium line for the concentrations, which is taken into account in the numerical simulations. The ammonia mass flux from gas to liquid phase and its concentration at the outlet of the computational domain is determined as a result of the simulations.

AbstractWe adopted an electrophoretic deposition method for the preparation of thin layers of insoluble composite nanoparticles composed of TiO2 core and about 2 nm thick shell of polythiophene, prepared by oxidative polymerization of thiophene. The reduced form of TiO2‐polythiophene composite material was deposited on the conductive surface from an ultrasonically generated microdispersion. Varying the dispersion media, applied voltage and the electrode arrangement made it possible to control the quality and morphology of the films. Compact semitransparent films deposited on ITO electrodes, suitable for photoelectrical measurements, were obtained within short deposition times.

Abstract The growth of world aviation traffic leads to an increase of the impact on the environment that is now becoming one of the main factors determining the development of the aviation industry. Computational fluid dynamics (CFD) has become an attractive tool to predict pollutant concentration in the real environment. CFD software represents the most advanced mathematics that can be applied to simulation different physical process, including the transfer and dilution of fluid flow from aircraft, vehicle and other sources. This paper is an attempt to compare numerical simulation results of exhaust gases jet from aircraft near aerodrome surface by three CFD codes: Fluent 6.3, OpenFOAM and SolidWorks. The work is also focused on assessment of the aerodrome surface influence on jet’s parameters (height and longitudinal coordinate of buoyancy effect) and on providing of initial data for further dispersion modeling. The obtained results are also aimed to improve complex model PolEmiCa.

Synthesis of a new biodiesel fuel, namely, isopropyl ester of rapeseed oil, is described. The performance properties of the synthesized product, other diesel fuels, and petroleum fuels are compared. The results of computational studies of the efficiency indices of diesel engine running on various fuels are furnished. It is concluded that the synthesized biofuel is of a high quality and can be used in diesel engines.

Using a mathematical model, the interconnected electromagnetic, mechanical and thermal processes in the electrodynamic catapult for an unmanned aerial vehicle (U A V) are calculated. Excitation of the windings of the inductor (WI) and the armature (WA) of the catapult is carried out by an aperiodic current pulse from a capacitive energy storage device (CES). The influence of the tire thickness and the corresponding number of turns of the windings on the amplitudes of the current, current density, electrodynamic force and the temperature rise of the windings are established. The influence of the aperiodic current feed pulse, which is realized by connecting an additional CES to the main CES, is established. It is shown that with an increase in the thickness of the copper bus bar and a corresponding decrease in the number of turns of the windings, the effect of the additional CES becomes more effective. The winding parameters are determined at which the highest speed and efficiency of the catapult is achieved when the windings are excited by various pulses. Experimental studies of the electrodynamic catapult model under excitation with aperiodic and aperiodic excitation with current pulses were carried out. It was found that the experimental and calculated electrical indicators are correlated with an accuracy of 5%, and mechanical indicators - with an accuracy of 12 %.

It was studied experimentally how the yield of the powder products in the process of continuous electrodischarge synthesis of carbon nanomaterials and the pyrolytic treatment of the concomitant gas mixtures depends on the structure and properties of the raw materials. Liquid organic substances—alcohols and acyclic and cyclic saturated hydrocarbons—were used as the raw materials.

Tools for optimizing the performance of parallel programs on multi-architectural distributed computing systems are considered. A method for optimizing the embedding of parallel MPI-program into computing clusters with a hierarchical communication network structure is described. An adaptive approach to the delta optimization of restore points is proposed for effective fault-tolerant simulation on distributed computing systems.