Rate Of Temperature Increase Research Articles

Vacuum pyrolysis of ammonium paratungstate: Study on reaction mechanism and morphology changes of product

At present, tungsten oxide is mainly produced by atmospheric decomposition of ammonium paratungstate (APT), which usually causes uneven particle size and morphology. In this paper, non-agglomerated tungsten oxide was prepared by vacuum pyrolysis (vacuum pressure is about 20 Pa) of APT. The vacuumpyrolysis mechanism and characterization changes of APT were investigated. The results showed that the pyrolysis of APT in a vacuum could be divided into five main stages based on thermal effect, crystallization water removing (25−170 °C), ammonia removing (170−250 °C), (NH4)6.84H3.16[H2W12O42] dissociation (250−390 °C), hexagonal ammonium tungsten bronze and WO3 part reduction (390−500 °C), h-WO3 crystal transformation (500−600 °C). The effects of pyrolysis temperature, heating rate, and holding time on the morphology and particle size of products were further studied. With increasing temperature, the particle size of the products decreased, and there was no agglomeration. Coarse tungsten oxide (62.43 μm) was obtained at a temperature increase rate of 1 °C/min. The shorter heat preservation time (10 min) was more conducive to the preparation of fine tungsten oxide (32.41 μm). The crystal morphology during APT decomposition into tungsten oxide was "hereditary". Compared with atmospheric decomposition, the vacuum environment is conducive to the preparation of narrow tungsten oxide products.

Embodied carbon assessment using a dynamic climate model: Case-study comparison of a concrete, steel and timber building structure

The enormous environmental impact of construction is becoming increasingly apparent and unacceptable to many structural engineers, whose designs typically account for the majority of a building’s embodied carbon. It is timely, therefore, that consensus is forming around a methodology for calculating embodied carbon. This encourages the inclusion of all life cycle stages, from material production and construction, through use and eventual demolition, disposal and reuse. In practice, however, end-of-life processes are fraught with uncertainty and often ignored, despite the potentially large associated carbon fluxes. Further uncertainty exists when considering bio-based construction materials, which store carbon during use. There are no widely-accepted means of accounting for timing of these carbon fluxes, despite the long service life of most buildings. Could we consider whole-life carbon in a more holistic and climate-focused way?This article uses dynamic life cycle assessment to convert greenhouse gas emission histories to key climate impacts using a simple dynamic model. The implications for structural design decisions are explored by comparing concrete, steel and timber options for a typical medium-rise building structure. Concrete is found to have a higher impact than steel, with the climate response of both options dominated by the large initial emissions of material production and construction. Timber has the smallest impact, for this example, under a typical scenario with sustainable forest management and re-emission of sequestered carbon at end-of-life. The analysis takes a forward-looking approach to sequestration, with timing corresponding to the growth of replanted trees. An optimistic timber scenario, whereby future carbon-capture technology avoids most end-of-life emissions, demonstrates the possibility of structures with small long-term climate cooling effects. Conversely, in a hypothetical worst-case scenario where no replanting or subsequent sequestration occurs, the long-term warming effect of the timber structure is increased by the net emission of biogenic carbon.Although end-of-life processes are important in the long-term, particularly for timber, the analysis also highlights the importance of the initial emissions from material production and construction. These cause high rates of short-term temperature increase and prolonged accumulation of radiative heat for all the buildings, but the impacts are again lowest for timber.Most importantly, the investigation shows how dynamic life cycle assessment can be used to explore climate impacts in a comprehensive, graphical and unbiased way. As a simple extension to established methodologies for calculating embodied carbon, it is a powerful decision making tool in the climate emergency.

Pengaruh Prosentase Kepekatan Kaca Film Terhadap Distribusi Termal dan Pencahayaan Kabin Kendaraan

Window film is a thin layer on car glass that functions as a medium for repelling sunlight. This study aims to determine the effect of percentage of window film density on the thermal and lighting distribution of the vehicle cabin. This research was conducted using a room model measuring 50x50x30 cm. The variation of window film uses two brands of Ultima and 3M, with the respective percentages of 40% and 60%. When the experiment was carried out in an open space, the irradiation process was carried out for 2 hours using the sun's rays at 11.00 - 13.00 WIB in each variation. Temperature measurement uses a digital thermometer on the surface of the coated glass (T1) and indoors (T2), while the measurement of light intensity uses a lux meter that is placed outdoors (I1) and indoors (I2). Data analysis using the equations of temperature rate and effectiveness of heat and light reduction. The results showed that the difference in the percentage of glass film density affected the rate of heat transfer and the intensity of the light entering the room. The heat transfer rate tends to increase in Q1 with a value of 58375.61 joules, and decrease in Q2 with a value of 1160.46 joules in the variation of 3M glass film brands with a 60% concentration level. Meanwhile, the average temperature increase rate is 0.002 ℃ / minute for all variations of window film brands with a light intensity of 0.007 - 0.008 lux.
 
 Keywords : window film, temperature rate, light intensity, heat transfer.

Design and simulation of turbogenerators for series hybrid electric vehicles

To reduce emissions and fuel consumption in the automotive world, researchers are looking for alternative energy converters in the series hybrid electric vehicle and previous studies demonstrate that turbogenerator technologies are promising candidates. This study presents a methodology for the design, modelization, and dynamic simulation of different turbogenerator thermodynamic architectures to compare their performances, compute their efficiencies and select the best candidate to replace the internal combustion engine in the series hybrid electric vehicle taking into account the startup phase, where the inertia of the components affect the performance of the machine. Therefore, four types of turbogenerator configurations were thermodynamically investigated. Then an extensive work was conducted to design the turbomachines components with high efficiencies, followed by a design procedure of the recuperators. Dynamic models of the turbogenerators were developed and simulated with a constant power start-up strategy where the data of the designed components were integrated into the models. Results show that the turbogenerators that contain a recuperator have a startup phase characterized by high fuel consumption for 70 s mainly caused by the thermal inertia of the recuperator that causes a reduction in turbogenerators efficiencies by about 3%. Moreover, the intercooled regenerative reheated turbogenerator presented a better performance than the other turbogenerators with the highest rate of temperature increase at the inlet of the combustion chamber resulting in the lowest fuel consumption. Consequently, the intercooled regenerative reheated turbogenerator was selected as the best candidate as it had the best dynamic performance, the highest efficiency 37.9%, and net specific work 205 kJ/kg for a turbine inlet temperature of 950 °C. The developed methodology in this paper could be applied to reproduce new turbogenerator energy architectures, compare their performances, and select the best designs.

Enhancing the compost maturation of swine manure and rice straw by applying bioaugmentation

Microorganisms capable of decomposing cellulose, xylan, starch and protein were individually isolated from swine manure compost and soil in this study. The correlations with pH, carbon source concentration, C/N ratio and enzyme activity among these isolated microorganisms were also investigated. Furthermore, the effect of additional inoculation in the compost was studied by measuring variations in the C/N ratio, enzyme activity and compost maturation rate. The inoculated microorganisms used in this study included four bacterial isolates and one commercial microorganism Phanerochaete chrysosporium. The results indicated that the isolated Kitasatospora phosalacinea strain C1, which is a cellulose-degraded microorganism, presented the highest enzyme activity at 31 ℃ and pH 5.5, while the C/N ratio was 0.8%. The isolated xylan-degraded microorganism Paenibacillus glycanilyticus X1 had the highest enzyme activity at 45 ℃ and pH 7.5, while the C/N ratio was 0.5%. The starch-degraded microorganism was identified as Bacillus licheniformis S3, and its highest enzyme activities were estimated to be 31 ℃ and pH 7.5 while the C/N ratio was 0.8%. The highest enzyme activity of the protein-degraded microorganism Brevinacillus agri E4 was obtained at 45 ℃ and pH 8.5, while the C/N ratio was 1.0%. The rate of temperature increase in the compost inoculated with P. chrysosporium was only higher than that of the compost without inoculation, and its compost maturation level was also lower than that of other composts with additional inoculation. The optimal initial C/N ratio of the compost was 27.5 and the final C/N ratio was 18.9. The composting results also indicated that the secondary inoculation would benefit compost maturation, and the lowest final C/N ratio of 17.0 was obtained.

An experimental study on the thermal characteristics of the Cell-To-Pack system

The development of electric vehicle batteries has resulted in high energy density battery pack. Cell-to-Pack (CTP) omits the cell module assembly, can reduce battery pack parts by 40%, improve the battery pack volume utilization rate by 15%–20%. However, the thermal characteristics of CTP under full operating conditions has yet to be verified, the CTP temperature calibration cycle under full working condition is time-consuming, and little analysis has been conducted on CTP internal temperature differentials and heat flow. The present study aims to thermal characteristics of CTP. Results show that CTP temperature calibration based on a thermal resistance grid can realize internal temperature reconstruction, optimum temperature arrangement, and shorten the calibration period by more than 60%. In addition, higher ambient temperatures can increase the maximum temperature of the jelly rolls in CTP cells, while lower ambient temperature can lead to larger differences in jelly roll temperature within a cell; and high-speed driving and fast charging can lead to the highest temperature increase rates under different working conditions up to 0.05 °C s−1.70% of the heat generated during cell discharge is used for self-heating, and the heat dissipation of liquid cooled plate is the main heat dissipation channel.

Numerical investigation on the dynamic response characteristics of a thermoelectric generator module under transient temperature excitations

In this work, a three-dimensional transient numerical model of a thermoelectric generator module considering the temperature-dependent properties and the topological connection of load resistance is proposed to study its dynamic response characteristics. The dynamic output power and conversion efficiency of the thermoelectric generator module under steady and different transient temperature excitations are compared and studied. A time delay exists in the output response of the thermoelectric generator module, and the time delay increases when the temperature rate increases. When the heat source temperature changes rapidly, the corresponding output power, conversion efficiency, and other thermal responses will show a more stable change trend. Moreover, the dynamic response characteristic of the output power is synchronous with that of the conversion efficiency. The periodic temperature excitation may amplify the output power, where the average output power of the sine and triangle waves are 4.93% and 2.82% respectively higher than the steady-state output power. However, the average conversion efficiency of both is almost identical to the steady-state conversion efficiency. The proposed model contributes to predicting the dynamic performance of thermoelectric generators, and can be further extended to the whole thermoelectric generator system.

Current Status and Variation since 1964 of the Glaciers around the Ebi Lake Basin in the Warming Climate

This work analyzed the spatial and temporal variations of the glaciers in the Ebi Lake basin during the period 1964 to 2019, based on the 1st and 2nd Chinese Glacier Inventories (CGI) and remote sensing data; this is believed to be the first long-term comprehensive remote sensing investigation on the glacier change in this area, and it also diagnosed the response of the glaciers to the warming climate by analyzing digital elevation modeling and meteorology. The results show that there are 988 glaciers in total in the basin, with a total area of 560 km2 and average area of 0.57 km2 for a single glacier. The area and number of the glaciers oriented north and northeast are 205 km2 (327 glaciers) and 180 km2 (265 glaciers), respectively. The glaciers are categorized into eight classes as per their area, which are less than 0.1, 0.1–0.5, 0.5–1.0, 1.0–2.0, 2.0–5.0, 5.0–10.0, 10.0–20.0, and greater than 20.0 km2, respectively. The smaller glaciers between 0.1 km2 and 10.0 km2 account for 509 km2 or 91% in total area, and, in particular, the glaciers smaller than 0.5 km2 account for 74% in the total number. The glacial area is concentrated at 3500–4000 m in altitude (512 km2 or 91.4% in total). The number of glaciers in the basin decreased by 10.5% or 116, and their area decreased by 263.29 km2 (−4.79 km2 a−1) or 32% (−0.58% a−1) from 1964 to 2019; the glaciers with an area between 2.0 km2 and 5.0 km2 decreased by the largest, −82.60 km2 or −40.67% in the total area at −1.50 km2 a−1 or −0.74% a−1), and the largest decrease in number (i.e., 126 glaciers) occurs between 0.1 km2 and 0.5 km2. The total ice storage in the basin decreased by 97.84–153.22 km3 from 1964 to 2019, equivalent to 88.06–137.90 km3 water (taking 0.9 g cm−3 as ice mass density). The temperature increase rate in the basin was +0.37 °C decade−1, while the precipitation was +13.61 mm decade−1 during the last fifty-five years. This analysis shows that the increase in precipitation in the basin was not sufficient to compensate the mass loss of glaciers caused by the warming during the same period. The increase in temperature was the dominant factor exceeding precipitation mass supply for ruling the retreat of the glaciers in the entire basin.

COMPARATIVE STUDY OF VARIOUS APPROACHES IN ANALYSIS OF TGA DATA OF DEVOLATILIZATION OF HIGH ASH INDIAN COAL

ABSTRACT Thermo gravimetric analysis (TGA) has been regularly employed for the estimation of devolatilization rates and measurement of char reactivity of coal. In general, TGA studies may be classified as isothermal or non-isothermal. In the first case temperature of the sample is kept constant whereas in case of latter the rate of temperature increase is kept constant. The current research work deals with the non-isothermal TGA study and kinetic analysis of three typical pulverized high-ash Indian coal samples each weighing around 15 mg. TGA experiments were carried out for four different heating rates (5, 10, 15, 20 K/min) and weight loss curves have been obtained. Out of the various methods proposed to analyze the TGA data, the following methods have been evaluated i) Friedman method, ii) Flynn-Wall-Ozawa method (FWO), iii) Kissinger method, iv) Kissinger-Akahira-Sunose (KAS) method, and v) Miura-Maki method. Activation energy and frequency factor to be used in the Arrhenius equation is calculated using all the above methods. The most accurate method for analyzing TGA data for high-ash Indian coal is FWO as per studies carried out in this research work.

Passive distributed temperature sensing (PDTS)-based moisture content estimation in agricultural soils under different vegetative canopies

A semi-empirical Boltzmann model is proposed to describe the relationship between the rate of temperature increase and soil moisture content, which can replace the existing complicated numerical iterative algorithm. The proposed method greatly simplifies the calculation process and improves the applicability of the passive distributed temperature sensing (PDTS) technology. A field test was performed in the Loess Plateau of China to validate the capability of this method. The field site has four typical land cover conditions: bare soil (G1), plastic mulch (G2), plastic mulch cover with potatoes (G3), and plastic much cover with maize (G4). The monitoring results indicate that for G1 and G2, the relationship between soil moisture content and the rate of temperature increase can be quantitatively described by the Boltzmann model with a root-mean-square error of 0.024 m3/m3. For G3, a linear relationship is found. In contrast, the PDTS technology is not applicable for G4 because a constant ground surface heat power from solar radiation and small air temperature fluctuations are preconditions of PDTS. If the coefficient of determination (R2) for fitting rate of temperature increase is larger than 0.9, the ground surface heat power by solar radiation can be considered as a constant.

Variation characteristics of temperature and precipitation on the northern slopes of the Himalaya region from 1979 to 2018

The northern slopes of Himalaya (NSH) have the highest average elevation in the world. It is difficult to assess how climate change has affected this region because only a few observations are available from the high terrain and harsh environment. This study investigates the long-term characteristics of temperature and precipitation in the NSH. Further, the association of these variations with atmospheric circulation patterns is also investigated. Our results indicated that the warming trend in this region is almost 1.5 times that of the TP region, 2 times that of China, and 3.5 times that of the world. Additionally, the warming rate of the NSH is more obvious than other regions in the Himalayas, which shows that different regions of the Himalayas have different sensitivity to climate change. Although the warming trend in the NSH region does not show obvious seasonal differences like the TP, the temperature increase rate in autumn and winter is still higher than that in spring and summer. The abrupt change point for the temperature increase in summer was about 5 years later than that in other seasons, indicating that the NSH region is more sensitive to climate warming in cooler seasons, which is similar to the western and northwestern Himalaya. Furthermore, the Southern Oscillation Index (SOI) displays significant relationships with the temperature in the NSH, meanwhile, the North Atlantic Oscillation index (NAO) and Western Pacific Subtropical High Intensity Index (WPI) also exist some correlations with seasonal temperature change. This indicating that the atmospheric circulation would also have affected the temperature increase in this region, especially in summer and winter. The changes in precipitation are only affected by the SOI during the monsoon season (June to September), indicating that ENSO influences precipitation changes through water vapor transmission. In contrast, the precipitation in the TP is correlated with NAO, SOI and WPI, which indicating the precipitation of the TP might be affected by multiple circulation systems.

Effect of Hydrogen Addition on the Energetic and Ecologic Parameters of an SI Engine Fueled by Biogas

The global policy solution seeks to reduce the usage of fossil fuels and greenhouse gas (GHG) emissions, and biogas (BG) represents a solutions to these problems. The use of biogas could help cope with increased amounts of waste and reduce usage of fossil fuels. Biogas could be used in compressed natural gas (CNG) engines, but the engine electronic control unit (ECU) needs to be modified. In this research, a spark ignition (SI) engine was tested for mixtures of biogas and hydrogen (volumetric hydrogen concentration of 0, 14, 24, 33, and 43%). In all experiments, two cases of spark timing (ST) were used: the first for an optimal mixture and the second for CNG. The results show that hydrogen increases combustion quality and reduces incomplete combustion products. Because of BG’s lower burning speed, the advanced ST increased brake thermal efficiency (BTE) by 4.3% when the engine was running on biogas. Adding 14 vol% of hydrogen (H2) increases the burning speed of the mixture and enhances BTE by 2.6% at spark timing optimal for CNG (CNG ST) and 0.6% at the optimal mixture ST (mixture ST). Analyses of the rate of heat release (ROHR), temperature, and pressure increase in the cylinder were carried out using utility BURN in AVL BOOST software.

＞500 W passively-cooled fiber cladding light stripper

To realize of passive-cooling high power fiber cladding light stripper, it is important to optimize the thermal management of both the fiber and the package. By using Teflon capillaries to make segmental etching configuration on fiber, using copper as the package material, and optimizing the package structure through finite element thermal simulations, cladding light stripper capable of handling 500 W power was designed and fabricated. It was experimentally verified that the stripping efficiency reached 23.7 dB and the temperature increase rate on the bare fiber of cladding light stripper was as low as 0.007 ℃/W. In addition, at 540 W of power injection, cladding light stripper could work continuously if mounted on water-cooled cold plate, and could work for 50 s each time if mounted on cold plate filled with phase-change material, with the maximum temperature of package being 58.7 ℃ and 80 ℃ respectively. The researches and results could provide valuable information to the design and development of high power fiber lasers.

Experimental Study on the Thermal Effect during Gas Adsorption and Desorption on the Coal Surface.

The thermal effect of coal adsorption/desorption gas is very important for understanding the evolution of coal temperature and interaction between coal and gas during coal and gas outburst. The pressure difference between the high gas pressure area in front of the working face and the low gas pressure area near the coal wall may affect the adsorption/desorption thermal effect. In order to reveal the characteristics of the coal adsorption/desorption gas thermal effect at different pressure differences, a thermo-hydro-mechanical-coupled experimental system of coal and gas was designed. Taking no.3 coal from Xinjing Mine as the research object, the characteristics of the coal adsorption/desorption gas thermal effect under different pressure differences are studied by using the cycle-step experiment method. It is found that coal adsorbs gas to release heat, while coal desorbs gas to absorb heat. Also, the temperature variation and temperature accumulation caused by adsorption are greater than those caused by desorption. Under the same pressure difference, the temperature increase rate during the adsorption changes from large to small, and the temperature variation gradually decreases; the temperature decrease rate during the desorption changes from small to large, and the temperature variation gradually increases; desorption is the reverse process of adsorption. The relation between temperature variation and gas pressure is linear, and the increasing range of temperature variation gradually decreases with the increase of pressure difference. The relation between temperature accumulation and gas pressure conforms to an exponential function, and the decreasing range of temperature accumulation gradually decreases with the increase of pressure difference. The greater the pressure difference, the greater is the energy variation caused by the adsorption/desorption thermal effect. The experimental results of different pressure differences can reflect the characteristics of the coal adsorption/desorption gas thermal effect under different geological structures or outburst types.

Effect of binder modification and thermal conditioning on asphalt binder rheology

ABSTRACT Permanent deformation is a common distress associated with a flexible pavement system. Virgin binders when unmodified cannot sustain detrimental environmental effects and heavy traffic loading. The environmental effects imposed on field pavements, for our experiments, were simulated by novel equipment called Thermal cycler. This simulates the conditioning of field pavements effectively and efficiently. Different modified blends of Elvaloy, Sulfur, and Eaton reagent were considered to study their effect on permanent deformation of asphalt binder, and their relative variation in G* was evaluated at different conditioning times. A Dynamic Shear Rheometer was used to assess different performance parameters for the evaluation of their rheological properties. It was observed that virgin binder is very sensitive to temperature variations and conditioning time. The rate of increase in failure temperature was higher for a virgin binder. Elvaloy modified bitumen showed more resistance to thermo-oxidative aging followed by Sulfur. The percentage increase in G* was 70% and 224% for Elvaloy and virgin binder, respectively. At the same value of PG 64, Elvaloy modified bitumen showed more resistance to permanent deformation as compared to Sulfur and Eaton reagent.

Climate-related inter-annual variability and long-term influence on wheat yield across canal-irrigated areas of Punjab, Pakistan

The association of climatic variables and climatic oscillations with wheat yield across 26 canal command areas (CCAs) in Punjab, Pakistan, is studied, for recent 34 years (1982–2015). Climatic variables include precipitation, temperature, dry/wet spell lengths, hot/cold spell lengths, wet/dry spell ratio along with climatic oscillations, and satellite-based vegetation index for the months of January to April (Rabi season). During Rabi season, temperature increase rate was 0.14 °C decade−1, whereas precipitation trends were spatially inhomogeneous and varied between – 2.7 mm decade−1 and + 5.4 mm decade−1. The precipitation, temperature, cold spell length, smoothed NDVI (ND), and standard deviation of ND (SDND) displayed significant correlations (0.31–0.96) with wheat yield at varying time scales. The inter-annual wheat yield variability displayed a gain of 415.7 kg ha−1 under present climatic conditions for all CCAs. Worse to extreme climatic conditions based on percentiles obtained from present climate displayed a reduction of wheat yield by 252.0 to 954.9 kg ha−1, respectively. The good to best climate in comparison to present climatic conditions added up 108.1 to 251.9 kg ha−1, respectively. The 11-year period of 1993–2003 was the most drought prone period with consecutive five years of drought (1998–2002), having decreased precipitation, small wet/dry spell ratio and increased temperature, and long dry/hot spell length during wheat growing season. The wheat yield is predicted based on multiple regression models with sizable skill (having an explained variance of 0.79 and a root mean squared error of 121.3 kg ha−1).

Evaluation of Thermoelectric Performance of Bi2Te3 Films as a Function of Temperature Increase Rate during Heat Treatment

Thin film thermoelectric generators are expected to be applied as power supplies for various Internet of Thing devices owing to their small size and flexible structure. However, the primary challenges of thin film thermoelectric generators are to improve their thermoelectric performance and reduce their manufacturing cost. Hence, Bi2Te3 thin films were deposited using direct current magnetron sputtering, followed by heat treatment at 573 K with different temperature increase rates ranging from 4 to 16 K/min. The in-plane Seebeck coefficient and electrical conductivity were measured at approximately 293 K. The in-plane thermal conductivity was calculated using the models to determine the power factor (PF) and dimensionless figure of merit (ZT). The temperature increase rate clearly affected the atomic composition, crystal orientation, and lattice strains, but not the crystallite size. The PF and dimensionless ZT increased as the temperature increase rate increased. The highest PF of 17.5 µW/(cm·K2) and ZT of 0.48 were achieved at a temperature increase rate of 16 K/min, while the unannealed thin film exhibited the lowest PF of 0.7 µW/(cm·K2) and ZT of 0.05. Therefore, this study demonstrated a method to enhance the thermoelectric performance of Bi2Te3 thin films by heat treatment at the appropriate temperature increase rate.

Enhanced effect of carbon nanofibers on heating efficiency of conductive cementitious composites under ohmic heating curing

Ohmic heating (OH) curing method has been proved to cure conductive fibers enhanced cementitious composites by electric-heating conversion under ultralow temperature, and this curing effect depends greatly on the heating efficiency. This paper presents a novel idea of utilizing carbon nanofibers (CNFs) to regulate and control the heating efficiency of carbon fibers (CFs) enhanced cementitious composites. The heating efficiency including peak curing temperature and temperature-increase rate of CF/CNFs reinforced cementitious composite (CF/CNF-CCC) with 0–0.3 vol% CNFs addition are traced. Results show that the increasing addition of CNFs shows a significantly increased enhancement effect to the heating efficiency during OH curing, in which the peak curing temperature and temperature-increase rate are increased from 44.8 °C to 0.139 °C/min to 73.2 °C and 0.39 °C/min as the content of CNFs is increased from 0 to 0.3 vol%. The microstructural heating mechanism based on CNFs distribution type in CF/CNF-CCC samples is clarified, two CNFs “bridge effects” are considered to effectively construct microscopic conductive network of CNFs among macroscopic conductive network of CFs. COMSOL Multiphysics simulation is conducted to further verify the improving effect of CNFs on the heating efficiency and to quantificationally guide the material composition design of CF/CNF-CCC for achieving the controllability of heating efficiency.

The state of heat resources and yield dynamics of the field crops in the conditions of the northern Steps of Ukraine

The most important environmental factors for the environment and habitat of plants include temperature. Agro-industrial production requires up-to-date information on the state of thermal resources and the response of plants to global warming within each region. The purpose of the research is to evaluate the state of thermal resources and the dynamics of crop yields in the Northern Steppe of Ukraine. Material for the research was the results of observations of the temperature regime of the AISW Dnipro (1961–1990 and 1991–2018) and data of winter wheat, spring barley, corn, sunflower in stationary experiments on control variants (DPDG “Dnipro”). Statistical data were used to evaluate the data by period: arithmetic mean (M); standard deviation (S); confidence interval (CL0.05) probability (P); repeatability (P × 100 %). Statistical processing was performed using applications in Excel 2003 and Statistica (version 6). Analysis of the thermal regime data showed that in 1991–2018, the average temperature for the year increased by 1.0 °C compared to the climatic norm (1961–1990), by 0.9 °C during the warm and cold periods. vegetation period of early cereals and late crops – by 0.8–1.0 °С. The average rate of increase in the average annual temperature in 1961–2018 was 0.31 ° C/10 years. Between 1991 and 2018, there were 15 cases with temperatures above 9.5 °C, with a recurrence rate of up to 53 %. The last decade (2009–2018) is characterized by a further increase in temperature during the year – by 1.5 ° C, the vegetation of early cere-als – by 1.6 °C, and late crops – by 2.0 °C. It is established that the warming is due to the temperature increase in the cold season – in January, February and March by 1.1,71.7 °C. Positive anomalies occur in July and August (+1.5 ° C). For estimating thermal resources, the important characteristics are the average temperature of the coldest and warmest months of the year. January 10-year average temperatures steadily increased from (-6.5) °C in 1961–1970, to (-4.0) °C in 2011–2018. Their annual variability decreased. The recurrence of high temperature (> -5 °C) in January increased from 34–35 % in 1961–1980 to 73 % in 2011–2018. The average values of July temperatures for 10 annual cycles have steadily increased from 20.8 to 23.0 °C since 1970. The recurrence of temperature> 23.0 °C for 1961–1970 was 2 cases and has increased 2.5 times in recent years. This increases the likelihood of sleepless periods. The positive trend leads to a shift in the dates of the steady transition of the average daily air temperature through 5 °C and the duration of the growing season. Over the last 18 years (2001–2018), it increased by 11–16 days (225 and 209–214). The incidence of such cases increased from 22 % to 44–50 %. At the same time, the increase in the duration of the period with an average daily temperature of ≥10 °C is not statistically significant. The average sums of effective temperatures ≥5 °C over the 10-year cycles in 2011–2018 were 2711 °C, which is 347 °C higher than the base period (1961–1990). Temperature totals increase linearly from 1971 to 2018. However, their recurrence (≥2711) in 2011–2018 sharply increases to 50 %. A close correlation (R2 = 0.75) was established between the duration of the period at ≥5 °C and the sum of effective heat ≥5 °C. A similar trend is typical for effective temperatures at ≥10 °C. The results of the accounting of crops show that for the whole period of observations their average values were: winter wheat (steam) – 4.44 t/ha; spring barley – 2.40 t/ha; corn – 4.32 t/ha; sunflower – 2.15 t/ha. Their distribution was characterized by significant fluctuations due to the variability of weather conditions. However, its maximum levels were noted in the post base period. Against the background of increasing supply of thermal resources in the region, there is an increase in their average yield: steam of winter – by 36 % (3.76 and 5.12 t/ha); spring barley – 24 % (2.14 and 2.65 t/ha ), corn – 11 % (4.14 and 4.59 t/ha), sunflower – 30 % (1.86 and 2.42 t/ha). The probability of forming the optimal yield level of steam winter, spring barley, corn and sunflower (≥4,44; ≥2,40; ≥4,32; ≥2,15 t/ha, respectively, for crops) in the post base period reaches 56–76 % whereas in 1961–1990 it was 25–43 %. Keywords: thermal resources, sum of temperatures, field crops, yield dynamics, adaptive properties.

Redesigning mini compact crucible furnace to improve its performance

Redesigning mini compact crucible furnace to improve heat insulation durability and to obtain the best exhaust pipe position is needed to achieve compatibility for aluminium casting practice. Performance test of the redesigned mini compact crucible furnace was conducted by variation of crucible, support and economizer. The rate of temperature increase, the aluminium melting rate, and gas consumption for melting aluminium specify the furnace performance. The temperature change was determined by digital infrared thermometer. Heat insulator on the inner side wall of mini compact crucible furnace were redesigned by using stainless steel plate cylinder combining with ceramic blanket D.96. Total weight of the furnace decreases by 28%. This insulator combination was able to accelerate the temperature increase, maintain the heating chamber temperature, and reduce the gas consumption. The furnace was able to melt 3 kg of aluminium in 35 minutes by consuming around 1.2 kg of liquefied petroleum gas. The economiser functioned well, was able to accelerate the temperature increase, and maintain the heating chamber temperature.