Hot Spots in the Weak Detonation Problem and Special Relativity

Problem statement: The initiation of a detonation in an explosive gaseous mixture in the high activation energy regime, in three space dimensions, typically leads to the formation of a singularity at one point, the “hot spot”. It would be suitable to have a description of the physical quantities in a full neighborhood of the hot spot. Results of this paper: (1) To achieve this, it is necessary to replace the blow-up time, or time when the hot spot first occurs, by the blow-up surface in four dimensions, which is the set of all hot spots for a class of observers related to one another by a Lorentz transformation. (2) A local general solution of the nonlinear system of PDE modeling fluid flow and chemistry, with a given blow-up surface, is obtained by the method of Fuchsian reduction. Advantages of this solution: (i) Earlier approximate solutions are contained in it, but the domain of validity of the present solution is larger; (ii) it provides a signature for this type of ignition mechanism; (iii) quantities that remain bounded at the hot spot may be determined, so that, in principle, this model may be tested against measurements; (iv) solutions with any number of hot spots may be constructed. The impact on numerical computation is also discussed.

Automatic Optical Measurement and Control of Benzene and Benzenoids in Natural Gas Pipelines

The presence of benzene and similar aromatic compounds in civil environments is due to anthropic actions but also to natural sources. Natural gas consists of a gas mixture where benzene and related compounds are usually presents. Thus, the detection of these compounds in natural gas pipelines is of the utmost importance as well as the control of the concentration level, which must remain below the limits consented by law. In this regard, it is of striking interest to engineer devices able to detect these compounds by automatic and continuous remote control. Here, we discuss the application of an optical device designed for the measurement of sulfured odorizing agents in natural gas pipelines aiming at the detection and the measurement of benzene, toluene, and xylenes (BTX) in the same contexts. The instrument consists of a customized UV spectrophotometer connected to an automatic control system able to provide in-field detections of BTX through a continuous and remote check of the gaseous mixture. Relatively to benzene, the instrument is characterized by values of LOD (level of detection) and LOQ (level of quantification) equal to 0.55 and 1.84 mg/Sm3, respectively. Similar limits are found for toluene and xylenes (LOD of 0.81, 1.05, 1.41, and 1.00 mg/Sm3 for toluene, meta-, ortho-, and para-xylene, respectively).

Experimental investigations of application of the water-steam оzone-containing gaseous mixture for prophylaxis and treatment of respiratory infectious diseases

Objective. Determination of the virus-cidal and bacterio-cidal action of the ozone-containing steam-water mixture, which was obtained, using apparatus POS-1, simulated on viral models of transmissive gastroenteritis of pigs of the coronaviruses family and polyresistant clinical strains of bacterial cultures, as well as adjustment of optimal parameters of ozone in the gaseous mixture content, which do not cause pathological changes in the organism’s organs and systems. Materials and methods. Apparatus POS-1, created by collective of Scientific-Methodical Centre «Medical Innovation Technologies»», was applied for production of the ozone-containing gaseous mixture. Virusological investigations were conducted on the base of the Institute of Epidemiology and Infectious Diseases named after L. V, Gromashevskiy. As a working material the models of virus of the pigs transmissive gastroenteritis of the coronaviruses family were applied. The series of bacteriological and experimental investigations were conducted on the base of Shalimov National Institute of Surgery and Transplantology NAMS of Ukraine. Polyresistant cultures in concentration of 108 colony-creating units per 1 ml were applied for bacteriological investigations. The experiment was conducted on white rats to study the gaseous ozone-containing mixture affection on living biological tissues. Results. Virusological investigations have shown, that in the 20 minutes exposition and a contact with extracellular virus the infection titer have lowered in 100 000 times, and in a 30 minutes exposition - a complete deactivation of virus have had occurred. Bacteriological investigations have revealed the complete absence of the cultures development after their processing with the ozone-containing mixture during 20 min. The results of swimming tests and behavioral reactions in white rats of control and experimental groups did not differ. Histological investigations of the respiratory organs tissues as well as of spleen, thyroid gland, kidneys and suprarenal glands did not reveal pathological effects of the ozone-containing mixture. Conclusion. Parameters of the ozone generation and delivery in the gaseous mixture content were studied and optimally selected. Investigations of the ozone-containing mixture affection on a viral strain of the coronaviruses family, as well as bacteriological investigations on polyresistant bacterial cultures have had confirmed its pronounced virus-cidal and bactericidal properties. Application of the ozone-containing mixture do not cause any pathological changes in the living organism organs and systems. This gaseous mixture may be used for prevention and treatment of respiratory infectious diseases of viral and bacterial genesis.

Impacts of Syngas Composition on Anaerobic Fermentation

Energy consumption places growing demands on modern lifestyles, which have direct impacts on the world’s natural environment. To attain the levels of sustainability required to avoid further consequences of changes in the climate, alternatives for sustainable production not only of energy but also materials and chemicals must be pursued. In this respect, syngas fermentation has recently attracted much attention, particularly from industries responsible for high levels of greenhouse gas emissions. Syngas can be obtained by thermochemical conversion of biomass, animal waste, coal, municipal solid wastes and other carbonaceous materials, and its composition depends on biomass properties and gasification conditions. It is defined as a gaseous mixture of CO and H2 but, depending on those parameters, it can also contain CO2, CH4 and secondary components, such as tar, oxygen and nitrogenous compounds. Even so, raw syngas can be used by anaerobic bacteria to produce biofuels (ethanol, butanol, etc.) and biochemicals (acetic acid, butyric acid, etc.). This review updates recent work on the influence of biomass properties and gasification parameters on syngas composition and details the influence of these secondary components and CO/H2 molar ratio on microbial metabolism and product formation. Moreover, the main challenges, opportunities and current developments in syngas fermentation are highlighted in this review.

Numerical study of continuously rotating detonation in two-fuel gaseous mixture

Numerical simulation of continuously rotating detonations of stoichiometric two-fuel mixture with air has been carried out for the cylindrical annular detonation chamber (DC) of the rocket-type engine. The syngas (1-α)СO+αH2, a binary mixture of hydrogen H2 and carbon monoxide CO, is taken. We studied the global flow structure in DC, and the detailed structure of the transverse wave (TW) front in the continuous rotating regime. Integral characteristics of the detonation process − the distribution of average values of static and total pressure along the length of the DC, and the value of specific impulse have been obtained. The region of existence of stable continuous detonation regime in coordinates of the stagnation pressure - temperature in injection manifold (receiver) and the geometric limit of stable TW have been determined.

Density and speed of sound in refrigerant vapor R-125 (31 wt. %) + R-134A (69 wt. %)

Using a constant volume piezometer and ultrasonic interferometer methods, the density and speed of sound in gaseous mixture R-125 (31 wt. %) + R-134a (69 wt. %) were measured within the temperature range from 293 to 393 K and at pressure from 0.18…0.47 to 2.5 MPa. The errors in the measuring temperature, pressure, density and speed of sound were ±20 mK, ±4 kPa, ± (0.15–0.3) %, ± (0.1–0.2) %, respectively. It was shown that the speed of sound values increase with temperature and decrease with pressure. The obtained results were compared with the calculations using the REFPROP software.

Low-cost natural carbon dioxide sorbents available in the Czech Republic

The article deals with the issue of carbon dioxide adsorption on mineral samples, two of which are rich in montmorillonite and one in kaolinite. The last comparative sample is clinoptilolite, which is widely used as a sorbent in agriculture, water treatment, etc. The theoretical part summarizes several current researches on the use of bentonites as adsorbents, both in their raw form and after various chemical treatments. The study presented here does not suggest any modification procedure, but tests untreated samples and samples subjected to calcinations at temperatures of 250-750 ° C. The calcination of units of grams was carried out by means of a carousel TGA, which made it possible to record curves of mass changes and to obtain a sufficient amount of calcinates for further analyses at the same time. From the point of view of achieving the highest specific surface area and the total pore volume, the optimal calcination temperature for the phyllosilicate samples ranged from 250 to 450 °C. Natural zeolite, on the other hand, showed a deterioration of both of these parameters at any temperature exceeding 150 °C. The same temperature dependence was found in the case of adsorption capacities determined by an automatic analyser Autosorb IQ using pure CO2. Measurements on this instrument also confirmed that selected inexpensive natural materials provide comparable adsorption capacities as the commercially available 13X molecular sieve used as a reference sample. Based on the performed analyses, the initial conditions of sample preparation for the upcoming measurement of adsorption properties on a larger apparatus operating in the PSA/TSA mode were determined. The primary aim of the tests using the selfdesigned high-pressure adsorption unit will be to determine the adsorption capacities that will take into account the temperature and pressure conditions in a real postcombustion carbon dioxide capture system. Unlike the automatic analyser described above, it will be possible to quantify the influence of important factors such as: flue gas humidity, the presence of other permanent gases (especially SO2) and last but not least various CO2 partial pressures and absolute pressure during adsorption and desorption. The experiments will verify the extent to which the presence of noncondensing moisture in the gaseous mixture is problematic. In the case of phyllosilicates, it is not just the parallel adsorption of H2O that affects the adsorption capacity available for CO2 capture. It will be empirically determined to what extent the swelling of the sorbent occurs in the wet gas, changing the gas flow through the layer and especially the pressure loss. The results of measurements on high-pressure apparatus will be the basis for the design and construction of a larger pilot scale unit.