Papers by Keyword: Temperature

Abstract: The main objective of this study is to optimize the reverse osmosis process in order to ensure the potabilization of water from the Oued Oum Er-Rbia, by determining the most influential parameters. To the best of our knowledge, this is the first study to apply daily PCA-based monitoring on Oued Oum Er-Rbia’s raw water to optimize membrane operation under Moroccan field conditions.To better understand the interactions between quality and hydraulic parameters influencing membrane performance, data were collected from Oued Oum Er-Rbia over multiple seasons. The parameters monitored included turbidity, salinity, temperature, and Silt Density Index (SDI), all known to affect fouling and pretreatment requirements.

Abstract: This study investigates the chemical characteristics of Eco Processed Pozzolan (ePP) and its surface modification with N, N-dimethyl dodecyl amine (oePP) at varying temperatures of 30°C, 40°C, and 50°C. Comprehensive analysis, including Fourier-transform infrared (FTIR), Field Emission Scanning Electron Microscopy (SEM), and X-ray diffraction (XRD) were employed to examine the structural, compositional, and morphological changes in ePP and oePP samples. The FTIR results revealed significant alterations in the functional groups of the modified samples, particularly in regions corresponding to alkyl and silanol groups after surface modification of ePP. XRD patterns demonstrated variations in crystallinity index, with values of 14.89%, 28.23%, 11.75%, and 15.89% for oePP at 50°C, 40°C, 30°C, and ePP, respectively. Peak analysis showed distinct differences in the crystalline phases present in each sample. FESEM images revealed enhanced surface morphology and increased particle agglomeration in the modified samples, especially at 40°C. The findings demonstrate that oePP exhibits significant potential for various applications owing to its enhanced adsorption properties, surface morphology, and structural stability.

Abstract: The results study of the accuracy of the temperature fire measurement by the sensors of the fire alarms in dynamic conditions with random temperature fluctuations, are presented. The statistical study of the accuracy measurement is based on the method of transformation of the random processes by the linear systems. The constructive approaches to optimizing and the accuracy improvement of the thermal sensors with the thermo-resistant sensitive element and the bridge measuring circuit in the dynamic conditions under random temperature fluctuations based on the choice of corresponding values of the characteristic parameter of the sensor and the constant time of its sensitive element have been proposed. Scientific novelty of the results is in the development model and in the method of analysis of the dynamic model of the thermal sensors with the thermo-resistant sensitive element in the form of a thin plate. It has been proved that the invariance of the accuracy of the ambient temperature measurement over time is possible. The obtained results allow solving the practical tasks determining the optimal parameters of the sensors under the conditions of fire temperature dynamics, taking into account the background random temperature fluctuations.

Abstract: The need to study the fire hazard of typical premises of a mobile communications base station was substantiated, in particular, regarding the feasibility of equipping it with an automatic (self-contained) fire-fighting system. Criteria for assessing the fire hazard of a mobile communications base station were developed. It was experimentally established that the greatest fire hazard in the premises of a mobile communications base station was related to the following devices: Alarm Box switching panel, input and distribution board, internal air conditioner unit and 12 V 100 A#2 batteries. Moreover, the latter two ones contribute to the spread of fire inside the premises. During the ignition of the 12 V 100 A#2 batteries, it was established that the surface of the outer wall further heated to a temperature of 80 °C, which did not exceed the critical one. Thus, the fire did not spread beyond the premises. It was established that equipping the premises of a mobile communications base station with a fire-fighting system in order to prevent the fire spreading beyond its boundaries was unreasonable.

Abstract: This scientific study presents experimental results of particle agglomeration and dispersing processes under various physicochemical conditions, focusing on the effects of temperature, particle concentration, and medium viscosity. Using numerical approaches and experimental data, patterns describing the changes in agglomeration rate and the features of dispersing system stability were identified. The key findings of the research include: the influence of temperature on agglomeration, high particle concentration, medium viscosity, dispersion under low particle concentration conditions. It is noteworthy that the results also confirm an exponential dependence of the agglomeration rate on temperature. However, at high particle concentrations, this effect is mitigated by the dominance of interparticle interactions, such as Van der Waals forces and electrostatic effects. Furthermore, in systems with low particle concentration and elevated temperature, agglomeration processes significantly slow down, indicating improved dispersing stability. The study opens new perspectives for controlling particle agglomeration and dispersing based on temperature, concentration, and the physical properties of the medium. The obtained data can be useful for improving existing technologies and developing new ones in areas where controlling the behavior of dispersed systems is essential.

Abstract: The construction, operating principles, and Li-ion battery thermal runaway mechanisms were analyzed. The external mechanical damage to a Li-ion battery with the uncontrolled thermal runaway development was investigated. The battery self-heating temperature regime was determined. A possible reactions set leading to intense materials self-heating and decomposition was considered. The battery self-heating stopping by immersing it in a container with a water excess relative to the stoichiometric amount for the lithium metal maximum mass that can accumulate was investigated. The change in resulting aqueous solution pH was measured, and the hydrogen release was also recorded. Reaction completion time dependences was established. The water required amount to absorb the heat that could be released during the reaction was calculated, which correlated with the experimental data. Possible measures to Li-ion batteries prevent and stop the burning were considered.

Abstract: The study assesses the efficiency of the heat-insulating coating on the surface of the PSV-250 steam-water heater, valves, and pipelines. The efficiency was evaluated using a non-contact method as part of a comprehensive study of heat losses through thermal imaging. During the inspection of the heater’s thermal condition, elements with surface temperatures ranging from +60 °C to +224.5 °C were identified, which poses a hazard from an occupational safety perspective. To prevent burns to maintenance personnel and reduce heat losses that lower the efficiency of thermal equipment, these surfaces must be insulated. To address the identified issues, it is recommended to install special removable insulation or apply a thermal insulation coating based on a liquid ceramic composite material.

Abstract: The aim of the work was to determine the possibility of not taking into account the orientation (vertical or horizontal) of the studied elements of steel-reinforced concrete slabs with a corrugated profile during their heating in a modular small-sized fire furnace. The work investigated the temperature distributions on the outer surface of the corrugated ceiling profile of a steel-reinforced concrete slab of horizontal orientation simulated in the fire furnace chamber. To create geometric models of the fire furnace chamber and the studied element, a CAD software complex was used. To solve the heat engineering problem, mathematical (numerical) methods were used, based on solving systems of differential equations of continuous media such as the Navier-Stokes equation and the Fourier heat conductivity equation. According to the results obtained, the temperature distribution on the outer surface of the steel profile of the reinforced concrete slab is uniform, the temperature deviation in different places on the surface does not exceed 7 %. The maximum temperature on the heating surface of the steel profile of the reinforced concrete slab in the last minute of computer simulation reached 921 °С and the average temperature at this time over the entire surface of the structure was 917 °С. To determine the appropriate orientation of the test sample during fire tests, a comparison of the obtained temperature distributions on the outer surface of the corrugated profile of a horizontally placed reinforced concrete slab with the temperature distributions on the outer surface of the corrugated profile of a vertically placed reinforced concrete slab, which were given in the previous work was made. Analysis of the average surface temperatures of the corrugated profile of a reinforced concrete slab of horizontal and vertical orientation showed that the temperature distribution over the surface of the profile was uniform in both cases and the results obtained show good reproducibility of the experiment during computer simulation. And the orientation of the tested elements does not affect the temperature distribution over the outer surface of the corrugated profile of a reinforced concrete slab in the simulated furnace.

Abstract: This paper compares the static properties for Silicon & SiC BJTs when connected in parallel, under various operating temperatures at various base currents and collector currents. This includes analysis of forward I-V characteristics, on-state resistance, DC gain, forward transfer characteristics and reverse leakage current to provide insights on paralleling of SiC & SiC BJTs.

Abstract: In this work, we investigate the static electrical parameters of 1200 V 4H-SiC power diodes with various designs and architectures (Schottky, PiN, and JBS with hexagonal or stripes anode), fabricated on two types of 150 mm substrates (single crystal 4H-SiC reference and 3C-poly silicon carbide based substrates: SmartSiC^TM). I(V) measurements are carried out in both reverse and forward modes to assess the impact of designs and substrates. Non-destructive avalanche mode is reached with similar performance (leakage, V_AV) observed for both substrates (due to identical drift layers and device structures). All diode designs on SmartSiC^TM exhibit a larger current conduction and less resistance in the ohmic regime (compared to bulk), whatever the temperature (up to 200°C). Partitioning model is also proposed for evaluating the substrate contribution on the measured specific resistance and on the observed SmartSiC^TM gains.