Papers by Keyword: Heating

Abstract: The housing sector accounts for a high percentage of total energy consumption in Iraq, with most energy usage on air-conditioning systems in summer to provide comfort to residents. This study simulates energy consumption for a typical 200 m², two-story, single-family building in Al Amarah city, Iraq, to compare heating, cooling, and total energy use across three different building configurations. Locally manufactured hollow concrete blocks made with 40 × 20 × 20 cm3 dimensions were adopted to improve their thermal performance by filling the cavities with Polystyrene insulation. The research examined three residential building configurations: (i) a base case built with traditional fired-clay brick, (ii) hollow concrete block walls free of insulation, and (iii) hollow concrete block walls incorporating thermal insulation. Energy simulations using eQUEST software were conducted, utilising the thermal response factor method as the primary tool to analyse the impact of external environmental conditions on cooling and heating loads. The results demonstrated significant annual energy savings for the building with hollow concrete blocks with and without insulation. However, insulated hollow concrete blocks showed reduced annual energy consumption compared to the common brick building system. Specifically, the insulated and uninsulated blocks attained energy savings by 29.4% and 16.08%, respectively, for north-facing orientation.

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: The structural changes of condensed fullerenes C₆₀ and C₂₈ at a temperature increase from 200 K to 2000 K have been studied by computational methods using the TERRA software for carbon-argon systems. The processes of destruction of fullerenes C₆₀ and C₂₈ molecules are presented, and the temperature ranges of their thermal stability are determined: up to 1000 K and up to 400 K, respectively. The following thermophysical parameters of the C₆₀-Ar and C₂₈-Ar systems are considered: specific volume, entropy, total enthalpy, total internal energy, equilibrium specific heat, molar mass of the gas phase, gas constant, and mass fraction of the condensed phase. A comparative analysis of their changes with increasing temperature is carried out. The results obtained in the course of thermodynamic modeling are similar to the results of a full-scale experiment conducted under similar conditions. In the future, the obtained data can be used to determine the explosive and fire-hazardous properties of fullerenes as a dispersed solid.

Abstract: Electron beam (EB) and heat treatment of silica-containing aggregates and mineral additives for Portland cement mortars is shown to affect their activity in alkali-silica reaction (ASR) damaging concrete structures. In the case of ordinary mortar based on the sand free of alkali-reactive inclusions, both heating to 900°C and EB processing result in a significant increase of reactivity growing with the absorbed dose in the range from 100 to 600 kGy and correlating with the increase in the content of acidic hydroxyl groups on the surface. For sand with reactive chalcedony inclusions, EB treatment results in the growth of their reactivity while heating provides its significant decrease. In case of mineral additives such as silica fume and metakaolin known as very effective ASR-inhibitors, similar processing leads to the increase of their activity in mitigation of ASR. The observed effect is promising for simulation of expansion processes caused by ASR and enhancement of concrete structure resistance to alkali destruction during exploration.

Abstract: The content of elements in the main mineral components of the ore, such as serpentine, talc, and chlorites, were determined. It was shown that, during heat treatment of the ore, in addition to the decomposition of hydrates and carbonates, serpentine decomposes and new phases (forsterite and enstatite) form. On the bases of analysis of the properties of the ore, patterns of phase transitions during heated in inert and reducing atmosphere were identified. It was found that the coal-thermal reduction of nickel and iron from oxides begins at temperatures above 800 °C, and from serpentines begins at temperatures above 1250 °C. It was found that, when heating the ore above 1200 °C in a mixture with a reducing agent, the metals reduce and form iron-nickel alloy. During electro-thermal smelting, the mode of which was determined by the melting points of slag (SiO₂ – MgO – FeO – CaO – Al₂O₃ system) and ferronickel, the ratio of Ni / Fe in the metallic phase was determined by the consumption of reducing agent (coal, coke).

Abstract: The results were shown in influence of fast heating parameters on the structure and properties of cold-worked alloy AMg6 with original hot-forged structure. Based on the measured data, the change of mechanical properties of cold-worked alloy AMg6 during the process of short duration heating was evaluated. There was reviewed the role of the temperature and the time of heat on the processes of softening the samples of cold-worked alloy AMg6. The stability of mechanical characteristics of hammer-hardened alloy AMg6 under elevated test temperatures was evaluated. It is shown that the return processes in cold-deformed AMg6 alloy during heating in the temperature range studied receive the most intensive development in the first 5–10 minutes, reducing the hardening effect from cold deformation, determined by tensile strength, respectively: by 8–9% with 100 °C; 26–27% at 150 °C; 37–38% at 200 °C; 42–44% at 250 °C and 50% at 300 °C. A decrease in the yield strength during high-speed heating in the temperature range studied is much faster ,compared with the change in the tensile strength. Hour exposure at 200 °C reduces the hardening effect on the yield strength from 340 MPa to 258 MPa, while the tensile strength decreases from 430 MPa to 385 MPa.

Abstract: The high strength silicon steel HY-TUF, applied for manufacturing of the heavy loaded aerospace and engineering parts, was investigated. The effect of the heating temperature in the range 900...1000 °C on the austenite grain size was studied. The steel under consideration had a significant scatter of the austenite grain size. The most intensive growth of the austenite grains was observed in the temperature range 975...1000 °C.

Abstract: Experimental studies of the influence of the heating temperature on the properties of pipe billets made of titanium alloys OT4 and OT4-1 in the formation of parts for the installation of pipeline systems without a protective atmosphere are presented.

Abstract: In this paper the electrothermal properties of the 4H-SiC JBS (Junction barrier Schottky) diode is investigated. FloTHERM and Silvaco TCAD are used for electrothermal simulation at the same time. Firstly, the effect of R_jc (junction-to-case thermal resistance) on junction temperature is investigated, the result shows that the junction temperature is more sensitive to the R_jc in the current heating mode because of some kind of positive feedback. Then, a current pulse is applied to the JBS, result shows that this kind of positive feedback is especially noticeable. Finally, the JBS will be compared with PIN under high current density pulsed operation, in order to analyze their thermal sensitivity to R_jc.

Abstract: One of the biggest environmental challenges of Vietnam is plastic wastes without recycling such as bottle, cans, plastic bag. The Vietnamese government have recognized these problems and called the reforming campaign to develop the sustainable technology to re-producing the wasted plastic. Thus, this research aims to contribute to deal with the issue by designing a plastic recycling machine. To satisfy domestic market of over 120 units at the first time, this research attempted to make a small machine at a low cost, but its throughput still reaches about 8kg plastic/hour and it can run within 16 consecutive hours a day. Hence, most of components is expected to be supplied by local vendors. As the result, the product price as well as maintenance cost is anticipated to be reduced. With the aim to produce the automated machine can incorporate continuous raw materials flow and at the same time move melted plastic in screw conveyor as defined by the regulation of the Programmable Logic Controllers (PLC) with timer to detect a velocity of melted plastic which come out from a nozzle of the screw conveyor and go to a mold. The hydraulic pressure, then, applies force to compressing and forming products. There are potential risks that can happen in fact, to deal with them. That is a reason Computer aid engineering and Finite element method modeling were conducted to make sure the force pressed in mold sufficiently and controlled the thickness of production as customer requirements.