Thermodynamic modelling of roasting of molybdenum sulphide concentrate with calcium hydroxide

This work aims to determine the conditions for the CaMoO4, CaSO4, Ca(ReO4)2 formation during oxidation of MoS2 and ReS2 in the presence of Ca(ОН)2. The concentrate from the Yuzhno-Shameyskoye deposit in the Sverdlovsk region, having 37% wt. Мо and 0.005% wt. Re, was selected as a feedstock for thermodynamic modelling of sweet roasting in the presence of Ca(OH)2. To determine the optimal amount of calcium-containing additives, the thermodynamic modelling was carried out using the following mass ratios: molybdenum concentrate: Ca(OH)2 = 1:0.8, 1:1, 1:1.2 and 1:1.5 in the temperature range of 100–800°С, with a step of 100°С, system pressure of 0.1 MPa in the air (molar ratio: molybdenum concentrate + Ca(OH)2: air = 1:5). The content of all sample components in moles was entered into the HSC 6.1 software package. The main reactions associated with the sweet roasting of molybdenum concentrate in the presence of calcium hydroxide were shown. It was established that the main phases formed as a result of roasting comprise CaSO4, CaSO3, MoO3, CaMoO4, CaMoO3 and CaReO4. The effect of temperature on the formation of the main gaseous products was studied under different mass ratios of molybdenum concentrate and Ca(OH)2. It was found that up to 600°C, with molybdenum concentrate to Ca(OH)2 ratio of 1:1, the concentrations of released sulphurous anhydride are lower than the maximum permissible concentrations. The calculated thermodynamic data was used for modelling the roasting process of molybdenum concentrate with calcium hydroxide. An optimal ratio necessary for the successful process operation was established: molybdenum concentrate: Ca(OH)2 = 1:1 by weight. Thermodynamic modelling showed that, in the temperature range of 100–600°С when using Ca(OH)2, no rhenium and molybdenum loss is observed, the release of sulfur is less than 10 mg/m3.

Impacts of Joule heating and viscous dissipation on MHD pulsatile flow of third grade nanofluid in a channel

The current exploration deals with the third grade hydromagnetic pulsating flow of blood-gold nanofluid in a channel with the presence of Ohmic heating, viscous dissipation and radiative heat. In the present analysis, blood (base fluid) is considered as third-grade fluid and gold (Au) as nanoparticle. This investigation is useful in the fields of food processing system, pressure surges (pulsatile flow application), biomedical engineering, nano drug delivery, radiotherapy, and cancer therapeutic (nanofluid application). Perturbation method is employed to transform the set of governing partial differential equations (PDEs) into the ordinary differential equations (ODEs) and then solved by employing the fourth order Runge-Kutta method with the aid of the shooting technique. The impacts of emerging dimensionless parameters of velocity, temperature, and heat transfer rate of blood-Au nanofluid are analysed via pictorial outcomes in detail. The obtained results depict that the improvement in viscous dissipation and heat source enhanced the temperature of third grade nanofluid. The velocity and temperature of the nanofluid are declining functions with the enhancement of frequency parameter, material parameter, and non-Newtonian parameter respectively. Intensifying the volume fraction of nanoparticle dwindles the velocity and temperature of nanofluid. Enhancing volume fraction and viscous dissipation accelerates the heat transfer rate of nanofluid. The velocity, temperature, and heat transfer rates are decreased by an escalation of the Hartmann number. Further, enhancing the radiation parameter reduces the heat transfer rate and temperature of nanofluid.

Optimization of Energy Consumption in the Pumping Station Supplying Two Zones of the Water Supply System

Water supply pumping stations are among the main energy-consuming elements in the water supply system. The energy optimization of a pumping station can significantly affect the energy consumption of a water utility. This article deals with the energy optimization of water pumping stations. The work assumes several variants of optimization of water supply pumping stations through changes in the water supply system, pressure changes in the pumping station, and modification of the number of pumps. After analyzing the network, conducting field tests, and creating a model of the water supply network, the network was calibrated in order to reproduce the existing water network as accurately as possible. Then, a variant analysis was performed, and the best optimization method for the pumping station was selected. In two variants, there was a decrease in electricity consumption; in three there, was an increase; in one, there was no change. By connecting the DMA zones and modifying the pressure in the pumping station, the energy consumption of the pumping stations was reduced. On this basis, it was found that it is possible to optimize the water pumping station by modifying the pumping station and work related to the network layout.

Investigation on design method of curved compression surface of inlet on scramjet

Suppose that curved compression surface of inlet consists of segments. Two curved surfaces formed by equal compression angles of the micro-element segments and a slight increase in the compression angle of the micro-element segments are designed respectively. The numerical simulation method is used to compare the performance of two curved surfaces with the reference three-wedge compression surface. Select NASA classic test data, in order to determine the turbulence model and calculation method chosen by the numerical simulation Fluent software. The results show: the configuration of the segment compression angle deeply affects compression efficiency of the curved surface compression system. Pressure gradient distribution on the compression surface with constant compression angles segments is nearly constant along the incoming flow direction, and the curved compression surface easily resist the separation of the boundary layer compared to three-wedges compression surface. The approximate calculation method of the bending shock profile is given.

Research and Experimental Analysis of Hydraulic Cylinder Position Control Mechanism Based on Pressure Detection

This paper studies the precise position control of the hydraulic cylinder in the hydraulic support. The aim of this paper is to develop a method of hydraulic cylinder position control based on pressure and flow coupling, which takes the coupling feedback of load and flow into account, especially in the scene of cooperative control under the condition of multiple actuators and variable load. This method solves the problems of slow movement and sliding effect of hydraulic support in the traditional time-dependent hydraulic position control, as well as better realizes the intelligent and unmanned development of the fully mechanized mining face. First, based on the flow continuity equation and Newton Euler dynamic equation, the flow and stroke control model with the input and output pressure of hydraulic cylinder is established. Then, the effectiveness and correctness of the control model are verified by the comparison between the hydraulic system simulation software, AMESim, and the experiment. Finally, a test system is built. When the system pressure is large than 10 MPa, the error between the data determined by the fitting algorithm and the actual detection data is within 5%, which verifies the effectiveness of the theory and simulation model.

Pre-Clinical Applications of High-Definition Manometry System to Investigate Pelvic Floor Muscle Contribution to Continence Mechanisms in a Rabbit Model

External anal sphincter (EAS), external urethral sphincters and puborectalis muscle (PRM) have important roles in the genesis of anal and urethral closure pressures. In the present study, we defined the contribution of these muscles alone and in combination to the sphincter closure function using a rabbit model and a high-definition manometry (HDM) system. A total of 12 female rabbits were anesthetized and prepared to measure anal, urethral, and vaginal canal pressures using a HDM system. Pressure was recorded at rest, and during electrical stimulation of the EAS and PRM. A few rabbits (n=6) were subjected to EAS injury and the impact of EAS injury on the closure pressure profile was also evaluated. Anal, urethral, and vaginal canal pressures recorded at rest and during electrical stimulation of EAS and PRM demonstrated distinct pressure profiles. EAS stimulation induced anal canal pressure increase whereas PRM stimulation increased the pressures in all the three orifices. Electrical stimulation of EAS after injury resulted in about 19% decrease in anal canal pressure. Simultaneous electrical stimulation of EAS and PRM resulted in an insignificant increase of individual anal canal pressures when compared to pressures recorded after EAS or PRM stimulations alone. Our data confirm that HDM is a viable system to measure dynamic pressure changes within the three orifices and to define the role of each muscle in the development of closure pressures within these orifices in preclinical studies.

Methodology for Assessing and Managing the Environmental Performance of Skidding and Feller Buncher Tractors

Systematic assessments on the effects of skidding systems on features of forest blueberry pine soil were conducted as part of this study. Assessing the ecological efficiency of forest skidding machines showed that the most significant impact (by 2.0–2.2 times) on soil compaction was observed at loading sites rather than during transportation. Lightweight loam density and sand density increased by 25% and 2%, respectively, after more than two passages of the skidding system. Pressure in 33L-32 tires of forestry machinery in operation on a solid surface varied from 46.5 kPa to 196 kPa at maximum load. Studying the impact of tires on soil compaction showed that the environmental efficiency of forestry equipment can be enhanced if the optimal tire pressure at average loads does not exceed 70 kPa for tracked vehicles and 150 kPa for wheeled vehicles in summer seasons. When ground grips were fully immersed, the pressure of forwarders on soil was reduced. These study results can be used to establish organizational and technological measures in order to manage the negative impact of skidding systems and to increase the environmental effects of their performance.

Experimental study of thermal limits with one-side heated smooth channel for plasma facing component safety

In order to stably operate the equipment inside the tokamak, which is loaded with a heat flux of several MW/m2 under the one-side heating condition, it is necessary to thoroughly prepare for various thermal engineering limits that may occur under the high heat flux load condition. In this study, we have experimentally explored critical heat flux (CHF) and onset of flow instability (OFI), which are considered potential threats in a DEMO fusion power plant. Specifically, the effect of system parameters on CHF was investigated. The results indicate that with an increase in subcooling and mass flux, the CHF increased, as it induced a faster bubble condensation near the CHF. As the system pressure increased, the CHF also increased. This is because the bubble size reduction effect was dominant in the pressure range of 1–10 bar. Most of the existing CHF correlations could evaluate the CHF with reasonable accuracy of within 25%; especially, the Boscary CHF correlation yielded the highest accuracy with an average error of 12%. Similar to CHF, OFI, which is a measure of the sudden fluctuations in the system pressure caused by a large amount of vapor generated due to the high heat flux, tended to increase as the subcooling, mass flow rate, and system pressure increased. Most of the existing OFI correlations yielded large error rates (more than 135%) as these correlations were primarily developed for micro-channels. Therefore, in this study, a new OFI correlation was developed using a Python code, in combination with an artificial intelligence (AI) regression method. The developed correlation can be used in the cooling system design of tokamaks, which involve a high-heat load condition on one-side of the reactor.