Results 1 - 10 of 47461
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[en] The technologies developed from 1973 on rational use, conservation and efficiency in the use of energy updated in a framework of sustain ability energetic and environment protection, it has not taken into account the concepts of quality of energy within of any energetic system (Source - Technology - Final Use), neither the favorable economic and technical implications of adopting the concepts of the Exergy and of exegetic efficiency, derivatives from the Second Law of the Thermodynamic, those which should be included as methods in the environmental and economic technical evaluations of an energetic system. This article presents the basic development of the concepts referenced from the Zero Law of the Thermodynamic, illustrating with examples the advantages to incorporate them as valuation and comparison parameters
[en] Works devoted to the development of calculation methods in the Laboratory of Chemical Thermodynamics at the Chemistry Department of Moscow State University are briefly reviewed. The main stages of this activity are described. The names of the scientists who contributed most to the development of these studies are given, along with the most valuable results of the last 60 years.
[en] After completing their introductory studies on thermodynamics at the university level, typically in a second-year university course, most students show a number of misconceptions. In this work, we identify some of those erroneous ideas and try to explain their origins. We also give a suggestion to attack the problem through a systematic and detailed study of various thermodynamic cycles. In the meantime, we derive some useful relations.
[en] We present an overview of recent experiments performed on water in the deeply supercooled region, a temperature region of fundamental importance in the science of water. We examine data generated by nuclear magnetic resonance, quasi-elastic neutron scattering, Fourier-transform infrared spectroscopy, and Raman spectroscopy, and study water confined in nanometer-scale environments. When contained within small pores, water does not crystallize and can be supercooled well below its homogeneous nucleation temperature T H. On this basis, it is possible to carry out a careful analysis of the well-known thermodynamic anomalies of water. Studying the temperature and pressure dependencies of water dynamics, we show that the liquid-liquid phase transition (LLPT) hypothesis represents a reliable model for describing liquid water. In this model, liquid water is a mixture of two different local structures: a low density liquid (LDL) and a high-density liquid (HDL). The LLPT line terminates at a low-T liquid-liquid critical point. We discuss the following experimental findings: 1.) the crossover from non-Arrhenius behavior at high T to Arrhenius behavior at low T in transport parameters; 2.) the breakdown of the Stokes-Einstein relation; 3.) the existence of a Widom line, which is the locus of points corresponding to a maximum correlation length in the P-T phase diagram and which ends in the liquid-liquid critical point; 4.) the direct observation of the LDL phase; and 5.) the minimum in the density at approximately 70 K below the temperature of the density maximum. In our opinion these results strongly support the LLPT hypothesis. All of the basic science and technology community should be impressed by the fact that, although the few ideas (apparently elementary) developed concerning water approximately 27 centuries ago have changed very little up to now, because of the current expansion in our knowledge in this area, they can begin to change in the near future.
[en] The article describes the experimental approach to elucidate the characteristics of the initial spontaneous boiling (spontaneous boiling-up) and the related effect of attainable liquid superheat. Presented is the analysis of the pioneering works on this subject carried out by G.V. Ermakov in the 60ies under the leadership of V.P. Skripov. They were the “healthy stimulus” for the revival of interest to liquid superheat in the scientific community. The article is devoted to the 80ies anniversary of Ermakov (1938–2012), who has been recognized for a series of investigations on thermodynamic properties of superheated liquids and the kinetics of liquid boiling-up . The article presents discussion of the most striking results obtained in Ermakov’s team and also the previously unpublished results. Selection of issues for discussion was dictated by the preferences of the authors who collaborated with Ermakov.
[en] Isosaccharinate (ISA-) is expected to be one of the important ligands in low-level nuclear wastes. Comprehensive thermodynamic data for complexation reactions of ISA- with any of the tetravalent actinides have not been available
[en] A new thermodynamic model of energetic molten fuel-coolant interactions is presented, in which the response of fluid around the interaction zone is treated explicitly. By assuming that this fluid is compressed reversibly and adiabatically, a qualified lower limit to the efficiency of conversion of thermal energy to mechanical work is obtained. A detailed comparison of the model predictions with the results of the SUW series of experiments at AEE Winfrith is made. The predicted efficiencies are found to be in close agreement with those determined experimentally. Model predictions for a system of infinite volume are also presented. (author)