Abstract Computer programs for the solution of everyday problems are very common because of the speed with which results can be obtained, which by traditional methods would be very laborious and especially those in which the solutions take repeated calculations. The work intends to demonstrate how, through programming, applying the exact solution method, fast and precise results can be obtained on similarities and differences between different geometries in heat transfer, which demonstrate the behavior, according to parameters, under equal conditions (geometric properties, diameters, lengths, thicknesses, volumes) and physical properties (thermal conductivity, specific heat and density), appreciating how they influence results such as cooling times, production according to the physical properties and design of the equipment, consumption rates, core and surface temperatures and others, according to the plastic pipe extrusion method, necessary in production processes that require constant monitoring.

Abstract The purpose of this work was to obtain the thermodynamic stability diagram that characterizes the copper/water/amylxanthate flotation system, as part of the theoretical foundation necessary for the analysis of the copperion flotation process with the flotation collector reagent potassium amylxanthate. From the system of fundamental chemical reactions and with the help of the Medusa software, the Eh-pH diagram was obtained, in which the stability zones of the different chemical species are defined and it is established that in the pH range from 4 to 13, the xanthogenic species of copper(I) and (II) coexist, whose ratio decreases with the increase of pH.

Abstract Lead-acid batteries account for 60% of the world’s electrical energy storage batteries. About 50% of global lead consumption comes from recycled and reused materials. Currently, pyrometallurgical methods account for more than 90% of lead recovery technology; however, these processes are criticized due to sulfur dioxide emissions from the decomposition of lead sulfate at elevated temperatures, in addition to particulate emissions. Lead recovery by recycling batteries by hydrometallurgical processes has been investigated as an alternative to pyrometallurgical processes. In the present work, a thermodynamic analysis of lead leaching with sodium citrate was performed. The thermodynamic analysis was based on the study of three stability diagrams constructed with Medusa® software. Leaching tests were carried out to get to know the system, corroborate the thermodynamic analysis performed, and study the behavior of the system. The results obtained show that it is possible to extract 100% lead with a leaching agent concentration of 0.25 M, a 1:1 solid-liquid ratio, and 25 ℃.

Abstract Thermal energy transfer processes are important problems to be solved in the field of engineering. In this field, heat exchangers are one of the most used equipment in the industry. The present investigation was carried out in an operating hydrogen sulfide cooler system, with the objective of determining the overall heat transfer coefficients by two methods, applying the passive experimentation procedure. With the Logarithmic Mean Temperature Difference (LMTD) method, values ranging from 11.1 to 73.3 W/(m2 ·K) were obtained, compared to 11.0 to 58.9 W/(m2 ·K) when applying the Effectiveness-Number of Transfer Units (ε-NTU) method. Although the results obtained were similar, for the thermal evaluation of the chiller system studied, it was recommended to employ the LMTD approach, used by most researchers.

Abstract The aim is to understand the thermal storage characteristics of porous media thermal storage materials under thermal dynamic conditions, and obtain the dynamic thermal storage characteristics parameters of thermal storage materials. In the 120 kW thermal dynamic thermal storage system of porous media, we studied the dynamic thermal storage characteristics of honeycomb porous ceramic thermal storage materials with different pore diameters (2.9, 4, 5.5 mm) and lengths (100–400 mm) under different hot flue gas conditions include thermal storage rate, thermal storage efficiency and storage. The results show that the relationship between the heat storage rate and time is parabolic, and the heat storage efficiency gradually decreases with the heat storage time. At the same time, the regenerative rate and unit regenerative resistance loss increase with the increase of specific surface area or the decrease of pore diameter of regenerator, and the regenerative efficiency increases with the increase of regenerator length. According to the experimental research and analysis, the dynamic heat storage characteristics of porous regenerator can be characterized by heat storage rate, heat storage efficiency and unit heat storage resistance loss.

Abstract Civil clean coke is a low-pollutanted civil clean fuel made of coal and multi-functional composite additives by high-temperature carbonization, which is of positive significance to solve the problem of air pollution caused by civil bulk combustion. However, problems such as high ignition temperature and poor combustion performance exist in the use of civil clean coke in the early stage. In this paper, Lvliang fat coal is taken as the research object. Coke samples are prepared by adding different additives and high-temperature carbonization. The influence of Na2CO3 on the combustion performance of civil clean coke is analyzed by TG-DTG, BET, thermodynamics kinetics and other methods. The results show that the civil clean coke prepared by high temperature dry distillation with 1.0% Na2CO3 added, the ignition temperature by impregnation method is 53 K lower than that of coke without additives; after adding Na2CO3, the TG and DTG curves of coke shifted significantly to the left, the average combustion rate increased from 0.38 mg/min to 0.75 mg/min, and the comprehensive combustion index increased from 2.01 × 10-10 mg2 /(min2 ·K3 ) to 11.14 × 10-10 mg2 /(min2 ·K3 ); after adding Na2CO3, the specific surface area of coke is significantly increased and the pore structure is more developed, which promotes the oxygen transfer in the combustion process and significantly reduces the apparent activation energy of the combustion system. The apparent activation energy in the low temperature zone is reduced from 454.28 kJ/mol to 306.85 kJ/mol, and the apparent activation energy in the high temperature zone is reduced from 557.36 kJ/mol to 95.36 kJ/mol. The combustion performance of civil clean coke is improved.

Abstract The need to dissipate high heat flux densities has led researchers and designers to employ phase change as a mechanism to achieve this goal and thereby achieve more compact heat exchanger equipment. In the present work, a study of the literature on boiling in mini-channels and microchannels was carried out. For this purpose, bibliographies dating from the 1990s to the present were consulted, which revealed the main parameters or topics that characterize this process in mini-channels and microchannels. Thus, the terms mini-channels and microchannels, forced flow boiling and flow regimes (map) are addressed. In addition, a summary of the equations for the determination of the heat transfer coefficient in two-phase regime (hdf) is presented.

Abstract The flow, combustion, heat transfer and NOx emission characteristics of a 600 MW subcritical W-flame boiler were numerically simulated under different combined operation modes of coal mills, and compared with the measured results. The results show that the combustion, average residence time, burnout rate, NOx emission characteristics and temperature distribution near the side wall of pulverized coal particles in the furnace have different effects on the combined operation mode of pulverized coal. In the combustion efficiency of give attention to two or more things, screen superheater section of fly ash carbon content and flue gas temperature of entrance at the same time, compared with six coal mill run at the same time, 5 coal mill run, shut down near the side wall of the coal mill is beneficial to reduce NOx emission concentration, to achieve the emission reduction, at the same time under the wing wall and side wall area chamber of a stove or furnace slagging significantly reduce.