Anomalous Temperature Dependences of Kinematic Viscosity in a Multicomponent Metal Melts

The temperature dependence of the kinematic viscosity was determined in the Fe84.5Cu0.6Nb0.5Si1.5B8.6P4C0.3 melt, which has an anomaly in the temperature range 1700–1900 K. The cluster sizes participating in the viscous flow were calculated using the transition state theory. It is shown that the activation energy Ea is directly proportional to the natural logarithm of the cluster size d, and the melt viscosity decreases with increasing cluster size. In the anomalous region at heating, the activation energy first decreases and then increases. This behavior was associated with the cluster dissolution and the subsequent formation of new clusters with a different size and chemical composition. Upon cooling, the viscosity corresponds to the melt structure formed at the maximum heating temperature.

Effect of Operating Temperatures and Working Pairs on Performance of Solar Adsorption Cooling System

Renewable energies including solar energy requirements for refrigeration and air conditioning are increasingly gaining interest due to the refrigerants friendly to the environment. However, it was found that these technologies have some limitations like the low performance and their high cost. This paper proposes a comparative study of a solar adsorption refrigeration machine. The study consists in determining the influence of thermodynamic parameters of operation on the performance of the system. This is based on a thermodynamic model using different types of adsorbent / adsorbate pairs. The main parameters considered in this study are: temperature of generation, evaporation, maximum heating temperature, condensation pressure as well as the type of the pair used: activated carbon / methanol and zeolite / water. Simulations for different thermodynamic parameters show that the COP is very sensitive to the generation and evaporation temperatures as well as the maximum heating temperature, on the other hand it was slightly influenced by the condensation pressure. The results obtained have shown that the AC / methanol pair is more profitable than the zeolite / water pair.

Influence of Operating Parameters on the Performance of an Adsorption Solar Refrigeration Machine

Renewable energies including solar energy requirements for refrigeration and air conditioning are increasingly gaining interest due to the refrigerants friendly to the environment. However, it was found that these technologies have some limitations like the low performance and their high cost. This paper proposes a comparative study of a solar adsorption refrigeration machine. The study consists in determining the optimal thermodynamic parameters of operation as well as their influences on the performance of the system. This is based on a thermodynamic model using different types of adsorbent / adsorbate pairs. The main parameters considered in this study are: temperature of generation, evaporation, maximum heating temperature, condensation pressure as well as the type of the pair used: activated carbon / methanol and zeolite / water. Simulations for different thermodynamic parameters show that the COP is very sensitive to the generation and evaporation temperatures as well as the maximum heating temperature, on the other hand it was slightly influenced by the condensation pressure. The results obtained have shown that the AC / methanol pair is more profitable than the zeolite / water pair.

INVESTIGATION OF THE MOISTURE BINDING FORMS IN PLANT RAW MATERIALS AND THERMAL CHARACTERISTICS DETERMINATION

In this article, the forms of moisture connection and the thermal characteristics of plant materials are studied. Rosehip and hawthorn fruits were chosen as the object of research. In the heat analyzer, a decrease in the mass of the product and an increase in temperature were found when the temperature was controlled in a certain gas environment. The curves of the dependence of the dog rose and hawthorn samples on the mass and temperature are given. DTA-1/10 galvanometer sensitivity; sensitivity of the DTG-1/5 galvanometer; the maximum heating temperature is 300° С and the rate of change of the furnace heating temperature is 3° С / min. The temperature features of the process of thermolysis of plant products have been studied. As a result of the study, the initial temperature, the highest and the final temperature of endothermic action were determined. The thermophysical properties of rose hips and hawthorn fruits were studied on the basis of experiments and the results are reflected in the tables below. Coefficients of thermal conductivity and specific heat of mass in the temperature range 20-80 ºC are given.

DEVELOPMENT OF A METHOD FOR APPLYING CONDUCTIVE TRACKS ON A PAPER BACKING

The article is devoted to the description of the technology of applying a conductive material by a layer-by-layer deposition method to a paper substrate.The material application method is "cold", i.e. the extruder operates at room temperature. However, in order to increase the printing speed, the printer is equipped with a heated plate with a maximum heating temperature of 120 degrees Celsius's. The description of the application method contains a mathematical description of the processes that occur during the application process. The possibility of applying the material and the accuracy of the line width depending on the speed of the print head are evaluated. This article provides a calculation of the mechanical parameters of the extruder components to determine the required resolution and accuracy of the feed.The article describes the method of application, the temperature of the environment 20 +/- 3 hail-sa Celsius.

COMPARATIVE ANALYSIS OF THE FOAM GLASS GRAVEL TYPES EXPERIMENTALLY PRODUCED BY MICROWAVE IRRADIATION

The paper presents an unconventional technique for manufacturing foam glass gravel. The numerous experimental results obtained by the authors in the last year using various manufacturing recipes common in the world industrial production by conventional techniques were selected and subjected to a qualitative and energy efficiency comparative analysis, aiming to determine the best foam glass gravel manufacturing procedure under the conditions of the use of the microwave energy. The optimum recipe was composed of 83% glass waste, 1 % glycerol, 8 % sodium silicate and 8 % water. The maximum heating temperature reached 823 ºC with a very economical energy consumption of 0.88 kWh/kg. The sample characteristics were apparent density-0.24 g/cm3, porosity-89.1% with pore size between 0.3 - 0.6 mm, thermal conductivity-0.063 W/m·K and compressive strength - 5.9 MPa, almost similar to those industrially obtained.

Structure and Properties of Al–0.6wt.%Zr Wire Alloy Manufactured by Direct Drawing of Electromagnetically Cast Wire Rod

The method of electromagnetic casting (EMC) was used to produce the long-length rod billet (with a diameter 12 mm) of aluminum alloy containing 0.6 wt.% Zr, 0.4%Fe, and 0.4%Si. The combination of high cooling rate (≈104 K/s) during alloy solidification and high temperature before casting (≈830 °C) caused zirconium to dissolve almost completely in the aluminum solid solution (Al). Additions of iron and silicon were completed in the uniformly distributed eutectic Al8Fe2Si phase particles with an average size of less than 1 µm. Such fine microstructure of the experimental alloy in as-cast state provides excellent deformability during wire production using direct cold drawing of EMC rod (94% reduction). TEM study of structure evolution in the as-drawn 3 mm wire revealed the onset of Al3Zr (L12) nanoparticle formation at 300 °C and almost-complete decomposition of (Al) at 400 °C. The distribution of Zr-containing nanoparticles is quite homogeneous, with their average size not exceeding 10 nm. Experimental wire alloy had the ultimate tensile strength (UTS) and electrical conductivity (EC) (234 MPa and 55.6 IACS, respectively) meeting the AT2 type specification. At the same time, the maximum heating temperature was much higher (400 versus 230 °C) and meets the AT4 type specification.

Nanostructured SiGe:Sb solid solutions with improved thermoelectric figure of merit

Thermoelectric Si 0,65 Ge 0,35 Sb δ materials have been fabricated by spark plasma sintering of Ge-Si-Sb powder mixture. The electronic properties of Si 0,65 Ge 0,35 Sb δ were found to be dependent on the uniformity of mixing of the components, which in turn is determined by the maximum heating temperature during solid-state sintering. Provided the concentration of donor Sb impurity is optimized the thermoelectric figure of merit for the investigated structures can be as high as 0.628 at the temperature of 490 °С, the latter value is comparable with world-known analogues obtained for Si 1- x Ge x P δ .

Cinnamon Wood Biochar Characteristics and Application Rates Influence on Crop Growth and Properties of Problematic Soil in Southern Sri Lanka

Biochar application has been provided various benefits to soil. This research was designed to assess the parameters between traditional biochar production system (TBS) and the innovative biochar production system (IS). The physical and chemical properties were assessed in two biochar materials that derived from traditional system (BCT) and the improved system (BCI). Also, soil properties changes and Ipomia aquatic plants growth were investigated after applying BCI at 0, 25, 50, 75 and 100% (v/v) input levels. Maximum heating temperature was increased up to 600 °C in IS since TBS reached to 500 °C. Further, time consumption in IS was reduced by 20% than TBS for the same amount of feedstock. Ash content was increased by 2% in IS compared to TBS. Biochar C content was high compared with the original feedstock in both BCT and BCI. Organic C% was increased by 55% and 75% in BCT and BCI, respectively. Particle-size was greater than 0.25mm in 90% of total biochar of both samples. BCI showed significantly high organic carbon, porosity, WHC, pH and EC than BCT. There was a significant difference of pH, EC, porosity, WHC, available P and Exchangeable K values among five treatments in the pot experiment. Mixing 75% biochar with acidic soil resulted neutral soil pH and recorded highest plant height and fresh weight compared with other combinations. Higher C content in BCI may enhance the soil carbon sequestration and improve the crop growth. Furthermore, farmers can be adapted to this system which helps to enhance the properties of acidic soil in their farmlands while opening the possibility of using Cinnamon wood as biochar material.

Optimasi Kebutuhan Batubara dalam Pembakaran Batu Gamping Di Desa Cempaka Mekar

PT Damwoo Indo has limestone quality requirements (CaCO3 grades) that will be burned with a minimum of CaCO3 grades by 50%. As for the calcium oxide products produced also have standards from consumers, namely the minimum CaO grades that will be accepted by consumers, which is 80%. The average coal calorific value is 6.294,70 kcal / kg. Products produced from the combustion process have several types, namely: a). gaso, b). jogso, c). miso, and d). saso. Products with gaso and jogso quality will be marketed because they have been burned completely, but for the quality of the miso product will be burned again because the product has not been completely burned. Whereas products with saso quality will be waste and disposed of because the product is overburned. Maximum heating temperature to get quicklime products with CaO grades >80% at the lowest 1.1350C and highest at 1.1700C. The maximum heating temperature was achieved using coal with the lowest heating value of 4.804,13 kcal / kg and the highest was 6.197,52 kcal / kg. From the results of the calculation of coal requirements needed in the limestone combustion process, the percentage of coal needs is an average of 12,26%. This means that it takes 12,26% of coal from calcium oxide products (CaO) produced from the combustion process.Abstrak. PT Damwoo Indo memiliki syarat kualitas batugamping (kadar CaCO3) yang akan dibakar yaitu minimal kadar CaCO3 sebesar 50%. Sedangkan untuk produk kapur tohor yang dihasilkan juga memiliki standar dari konsumen yaitu kadar CaO minimal yang akan diterima oleh konsumen yaitu sebesar 80%. Nilai kalor batubara rata-rata adalah sebesar 6.294,70 kkal/kg. Produk yang dihasilkan dari proses pembakaran memiliki beberapa jenis yaitu : a). gaso, b). jogso, c). miso, dan d). saso. Produk dengan kualitas gaso dan jogso akan dipasarkan karena sudah terbakar secara sempurna, namun untuk kualitas produk miso akan dilakukan pembakaran kembali dikarenakan produk belum terbakar sempurna. Sedangkan untuk produk dengan kualitas saso akan menjadi limbah dan dibuang dikarenakan produk tersebut overburned. Suhu pemanasan maksimal untuk mendapatkan produk kapur tohor dengan kadar CaO >80% paling rendah 1.1350C dan paling tinggi 1.1700C. Suhu pemanasan maksimal dicapai menggunakan batubara dengan nilai kalor paling rendah 4.804,13 kkal/kg dan paling tinggi 6.197,52 kkal/kg. Dari hasil perhitungan kebutuhan batubara yang dibutuhkan dalam proses pembakaran batugamping, diperoleh persentase kebutuhan batubara rata-rata sebesar 12,26%. Hal tersebut berarti dibutuhkan 12,26% batubara dari produk kapur tohor (CaO) yang dihasilkan dari proses pembakaran.