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Abstract Additional experimental data concerning the kinetics of Ni-Mo codeposition were obtained by investigating cathodic polarization using a rotating disc electrode. The Ni-Mo alloys were deposited from an ammonium citrate bath. The alloy deposition was controlled by activation in the case of low values of the cathode potential and by diffusion in the case of higher values. The hydrogen discharge was found to be diffusion controlled. The inductive influence of nickel results in depolarization of the reduction of molybdenum which cannot be deposited separately. An increase in the disc rotation speed caused an increase in the maximum cathode efficiency and in the molybdenum content of the alloy.

For economic reasons, expansions of transmission networks are based on a compromise between capital cost and security of power system operation. At the same time, the power system must withstand typical highly likely contingencies. Various emergency state control systems, also called special protections, prevent emergencies following less likely contingencies. This paper describes overloads emergency state control (OLEC) used for the alleviation of overload in transmission networks near a power plant. Such control uses the functions of automated power reduction of generating units and has been implemented for a large steam power plant. The OLEC presented here uses different methods of generation curtailment for steam generation units. A case study illustrates the efficiency of the proposed control method.

Abstract Coal gasification is accompanied with formation of tars that cause equipment problems and have to be removed from the raw gas. Our previous studies proved that nickel supported ceria-zirconia catalyst (Ni/CZ) reveals high activity towards decomposition of toluene and 1-methylnaphthalene (1-MN) via steam reforming reaction (SR). However, the components of the raw gas from coal gasification (i.e. H2, CO, CO2 and CH4) may influence the performance of Ni/CZ catalyst. The influence of particular components of the raw gas on catalyst performance during SR of model tar compounds have been studied and discussed in this paper. It has been found that H2 and CO addition to the steam reforming feed drastically decreases the activity of Ni/CZ catalyst, whereas CO2 presence enhances conversion of toluene and 1-MN mixture owing to the occurrence of dry reforming reaction (DR). It has also been observed that methane, which is present in the raw gas from coal gasification consumes partly both the H2O and CO2, causing some decrease in conversion of model tar compounds. The influence of contact time (tc) on hydrocarbons conversion and the participation of (DR) have been examined. As was observed, lower contact times lead to decrease in hydrocarbons conversion in SR, making the same participation of DR more pronounced than for higher tc values. This work proves that Ni/CZ catalyst can be used for removal of tarry compounds via the catalytic hot gas cleaning of the raw gas form coal gasification.

Abstract Grape pomace is a by-product of the wine making industry with great availability and energetic potential. Torrefaction is a pre-treatment that may enhance the biomass quality as a fuel, and consists in exposing the biomass to an inert atmosphere at a temperature between 200 °C and 300 °C. This study evaluates the combustion characteristics of raw and torrefied grape pomace in a thermogravimetric analyzer and in a drop tube furnace. Initially, the raw grape pomace was torrefied in an argon inert atmosphere at 260 °C. Subsequently, the combustion of the raw and torrefied grape pomace was examined in the thermogravimetric analyzer through non-isothermal runs at a heating rate of 10 °C/min from room temperature to 800 °C. Finally, the combustion of both biomass residues was evaluated in the drop tube furnace at 1100 °C. The data reported includes gas temperature, major gas species concentration and particle burnout measured along the axis of the drop tube furnace. The main conclusions of this study are (i) for the devolatilization stage, the thermogravimetric data yielded apparent activation energy values of 84.9 and 85.2 kJ mol−1, and for the char oxidation stage of 137.5 and 109.2 kJ mol−1 for the raw and torrefied grape pomace, respectively; (ii) the NOx concentrations along the drop tube furnace were always higher for the combustion of the torrefied grape pomace than for the combustion of the raw grape pomace because the former residue has a higher nitrogen content; and (iii) the burnout values along the drop tube furnace were always lower for the combustion of the torrefied grape pomace than for the combustion of the raw grape pomace because the former residue has a lower volatile content and a higher fixed carbon content.

The accuracy of the moments method is examined by comparison of approximate and exact values of the first three moments of solutions of the aerosol dynamics equation when only condensation and removal are taken into account. The log-normal and γ initial distributions are considered. Errors are expressed in terms of nondimensional independent variables and are found to be small.

Abstract The transportation of liquefied natural gas by sea has a strategic function for ensuring the energy security of Poland and, in a broader perspective, also of the countries in the Central and Eastern Europe region (primarily the Visegrad Group - V4 and others). The article points out the importance of Polish LNG/FSRU terminals in diversification and building the region's energy independence. It analyzes the security environment of the Baltic coastal waters, which is the arena for the activity of many countries with different multidimensional interests. A package of threats to maritime critical infrastructure facilities (LNG/FSRU terminals) and cryogenic tankers in the air, surface, and underwater domains is identified, noting the dynamic nature of many of them. The author analyzes the capabilities (strengths and weaknesses) of autonomous maritime systems (USV, UUV-ROV, UAV) in terms of their use to increase the effectiveness of LNG/FSRU terminal security systems. Possibilities of cooperation and achieving a synergy effect within the combined architecture of USV/UUV-ROV/UAV platforms are also indicated. The article presents a package of missions that autonomous systems can perform to increase the safety of operators and reduce the response time to threats, thus increasing the level of protection. The article presents a vision of a modular USV base platform model as a base element for an autonomous system dedicated to protecting LNG terminal/FSRU infrastructure and cryogenic tankers.

Abstract A one-dimensional mathematical model of the R744 two-phase ejector for expansion work recovery is presented in this paper. Governing equations were formulated for all passages of the ejector based on the differential equations for mass, momentum, and energy balance as well as a differential representation for the equation of state. For two-flow sections (mixer and diffuser) closing equations for mass, momentum and energy transfer between the primary and secondary flow were introduced. This model utilises the Delayed Equilibrium Model along with the Homogeneous Nucleation Theory for the purpose of the metastable state analysis for a transcritical flow with delayed flashing over the motive nozzle. The thermal properties model was based on a real fluid approach, where the REFPROP 8.0 database was used. Based on the results of experimental tests performed at SINTEF Energi Laboratory, the model was validated for a typical range of operating conditions. The range of available simulation output allowed for the creation of 1D profiles of local values for the flow variables and the computation of the overall indicators, such as pressure lift and expansion work recovery efficiency.

Abstract In the summer of 1989 a survey was conducted to collect data on household-energy consumption in Indian cities. The survey was conducted in three urban areas of varying sizes. The end-uses considered were cooking, water heating, lighting, air cooling, entertainment, cold storage, and washing/laundry. The surveys involved examination of the types and quantities of energy used to satisfy each of these services. The survey sample in each of the three cities was broken down by income group, allowing for a careful examination of the influence of household income on lifestyle patterns and related energy use choices. Among the houses surveyed were 75 households in Pune, India, that took part in a 1982 household energy study as well. The re-surveying process allowed for an analysis of longitudinal changes in residential energy use. Based on the survey findings, a number of recommendations are provided for improving the provision and use of energy in urban households in India.