Steam Conditions Research Articles

Thermal-hydraulic assessment of Once-Through Steam Generators for EU-DEMO WCLL Breeding Blanket primary cooling system application

Once-Through Steam Generators (OTSGs) were recently selected to be installed in the Primary Heat Transfer Systems (PHTS) related to EU-DEMO WCLL Breeding Blanket (BB). Referring to the Balance of Plant Direct Coupling Design (BoP-DCD) option, these components are used to deliver the thermal power removed from the two principal blanket subsystems, i.e. First Wall (FW) and Breeder Zone (BZ), to the Power Conversion System (PCS).OTSG design foresees a vertical component with primary water moving downward inside tube bundle and secondary fluid flowing throughout shell in counter current. The latter moves firstly downwards through the annular downcomer and then goes up in the central riser, where it boils up to super-heated steam conditions. Then, it is deflected by the upper tubesheet, flows again downwards along the steam downcomer and exits through the laterally connected steam nozzles.In the last years, as part of the research activities associated to the Work Package Balance of Plant (WPBoP), a detailed analysis of the steam generator, aimed at deeply understanding the main thermal-hydraulic aspects characterizing its performances during the pulsed regime of DEMO normal operations, was performed. To fulfil this scope, a complete model of the component was prepared by using the best-estimate system code RELAP5/MOD3.3, selected to be also the reference design verification tool.During operations, OTSG experiences full-load and low-load alternative phases with rapid transitions from one another. The steam generator capability to follow such load variations avoiding the occurrence of instabilities in the component was studied. The computational activity carried out was a preliminary thermal-hydraulic characterization of the component conceptual design during both pulse and dwell phases. The feedbacks of this analysis were also fundamental for the conceptualization of the steam generator mock-up to be installed in the planned STEAM facility that will be built at the ENEA Research center of Brasimone.

Heat treatment of poplar plywood: modifications in physical, mechanical and durability properties

Plywood made of poplar are limited to indoor usages since poplar exhibits a rather low natural durability. Recently, wood heat treatments have been applied to improve properties such as decay susceptibility and dimensional stability. This study examines the potential of exposing poplar plywood to heat treatment to extend the potential of applications of this engineered wood product to outdoor end uses, and new markets accordingly. Plywood panels were glued with two different adhesive formulations based on the same melamine-urea-formaldehyde (MUF) resin to compare their respective ability to resist to the heat treatment. These different plywoods were thermally modified in saturated steam conditions at 215 °C for 2 hours following the ThermoWood® process, up to reach 14% in mass loss. The durability improvement brought by the heat treatment was assessed in order to evaluate any possible outdoor uses for such plywood. After all the conducted analyses, the potential to use heat treated poplar plywoods in humid interior and protected exterior service conditions was confirmed.

Experimental Investigation on the Effect of Curing Condition and Admixture on Meso-Structure of Recycled Aggregate Concrete Based on X-ray CT

This study addresses the meso-structure of recycled aggregate concrete with different admixture and c;uring condition. The RCA (Recycled concrete aggregate) with admixture of slag power and fly ash and curing condition of steam was casted. X-ray CT (Computed tomography) was used to obtain meso-structure of RCA, and the pore structure, aggregate, and interface traction zone were analyzed. The results show that steam curing not only increases the pore volume but also makes the pore morphology more complex, the fractal dimension increases, the proportion of spherical pores decreases, and the pores develop from spherical to flat and slender with the increase of steam curing temperature. The porosity of micron pores in recycled aggregate concrete is about 2.3%, in which the pores with aperture less than 300 μm accounts for more than 85%. The thickness of the interface area between recycled aggregate and new mortar is about 200 μm, and the crack width in recycled aggregate is about 300– 400 μm.

Boundary condition coupling methods and its application to BOP-integrated transient simulation of SMART

The load-following operation of small modular reactors (SMRs) requires accurate prediction of transient behaviors that can occur in the balance of plants (BOP) and the nuclear steam supply system (NSSS). However, 1-D thermal-hydraulics analysis codes developed for safety and performance analysis have conventionally excluded the BOP from the simulation by assuming ideal boundary conditions for the main steam and feed water (MS/FW) systems, i.e., an open loop. In this study, we introduced a lumped model of BOP fluid system and coupled it with NSSS without any ideal boundary conditions, i.e., in a closed loop. Various methods for coupling boundary conditions at MS/FW were tested to validate their combination in terms of minimizing numerical instability, which mainly arises from the coupled boundaries. The method exhibiting the best performance was selected and applied to a transient simulation of an integrated NSSS and BOP system of a SMART. For a transient event with core power change of 100–20-100%, the simulation exhibited numerical stability throughout the system without any significant perturbation of thermal-hydraulic parameters. Thus, the introduced boundary-condition coupling method and BOP fluid system model can expectedly be employed for the transient simulation and performance analysis of SMRs requiring daily load-following operations.

Degradation of microstructure and strength properties of heat-resistant steels operating under variable loads

The paper presents the results of the structure and mechanical tests of the low-alloy steel 14MoV6-3 which shows internal damage after long-term creep service. The tests of mechanical properties, including: tensile and yield strength at room temperature, yield strength at elevated temperature (+540 °C) and brittle transition temperature, were carried out on longitudinal samples in accordance with the requirements of standards for elements pressure equipment. The internal damage of the tested material was also classified depending on the degree of wear, based on the principles set out in the industry specification. It was shown that the strength properties of the tested material from pipelines operated under primary steam conditions decrease with increasing service time. Microscopic tests (Scanning Electron Microscope SEM) revealed that the cause of damage to steel with a ferrite-bainite structure after long-term operation is the cavitation cracking mechanism. The study of the microstructure was also carried out by means of the backscattered electron diffraction method EBSD using the IQ, KAM and GOS functions. These parameters are very important in terms of analysis of the occurring structural changes in the fatigue and creep processes. They allow to determine the deformed part of the substructure subjected to these processes.

Modern Coal-Fired Power Units for Ultra-Supercritical Steam Conditions (Review)

Modern Coal-Fired Power Units for Ultra-Supercritical Steam Conditions (Review)

Long-Exposure Air and Steam Oxidation Characteristics of IN 617 Alloys

India’s growing power demands and emission norms require more efficient coal-based power plants. The shifting of power plants from subcritical to ultra-supercritical (USC) steam conditions could improve efficiency by 12% and reduce CO2 emissions by 35%. There is a need to develop and qualify materials under ultra-supercritical steam conditions with high temperatures and high pressures in laboratory scale. The sample materials were exposed to high temperatures of 700 °C under air and high pressure steam at 700 °C/243 bars for 1000 h in as-received and grain-boundary-enhanced conditions. Grain boundary enhancement included optimization of a thermo-mechanical process involving cold rolling and annealing of samples. The effect of air and steam oxidation on IN 617, a nickel-based candidate superalloy, was analysed. Steam oxidation was performed on a custom-built PARR 4650 series autoclave, and the oxidized samples were characterised under scanning electron microscopy, to evaluate the oxide scales. The grain-boundary-engineered material performed better than the as-received samples. IN 617 overall fared better under both air and steam conditions, with far less weight gains.

Study on the Mechanism of Phenylacetaldehyde Formation in a Chinese Water Chestnut-Based Medium during the Steaming Process.

The white pulp of the Chinese water chestnut (CWC) is crisp and sweet with delicious flavours and is an important ingredient in many Chinese dishes. Phenylacetaldehyde is a characteristic flavoured substance produced in the steaming and cooking process of CWC. The steaming process and conditions were simulated to construct three Maillard reaction systems which consisted of glucose and phenylalanine, and of both alone. The simulation results showed that glucose and phenylalanine were the reaction substrates for the formation of phenylacetaldehyde. The intermediate α-dicarbonyl compounds (α-DCs) and the final products of the simulated system were detected by solid-phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS) methods. Through the above methods the formation mechanism of phenylacetaldehyde is clarified; under the conditions of the steaming process, glucose is caramelized to produce Methylglyoxal (MGO), 2,3-Butanedione (BD), Glyoxal (GO) and other α-DCs. α-DCs and phenylalanine undergo a Strecker degradation reaction to generate phenylacetaldehyde. The optimal ratio of the amount of substance of glucose to phenylalanine for Maillard reaction is 1:4. The results can provide scientific reference for the regulation of flavour substances and the evaluation of flavour quality in the steaming process of fruits and vegetables.

Synergetic effects of hydrothermal treatment on the behavior of toxic sludge-modified geopolymer: Immobilization of cerium and lead, textural characteristics, and mechanical efficiency

Geopolymers have been subjected as a promising strategy for heavy metals immobilization due to their sustainability (environmental and energy saving). This study proposed a novel hydrothermal technology for the solidification/stabilization of lead and cerium present in a sludge resulting from the glass polishing process. Slag and fly-ash (50wt.%slag + 50wt.%fly-ash) activated with 6 wt% NaOH solution were used as base materials for geopolymer fabrication. The sludge was incorporated in the fabricated geopolymeric composite as a fly-ash replacement (10, 20 and 30 wt%). The impact of sludge incorporation and different curing regimes (humidity at 20 °C and 80 °C for 28-days and hydrothermal treatment at 3 and 6 bar for 1, 2, 6, 12 and 24 hrs) on the mechanical and textural characteristics as well as the formed phases were investigated via compression test, N2-adsorption/desorption technique, SEM/EDX, TGA/DSC and XRD. Moreover, the efficiency of the immobilization process was examined by determining the concentration of lead and cerium in the leachate solution (0.1 M HNO3 and 0.1 M CH3COOH) using Inductively Coupled Plasma Mass Spectroscopy to ensure the safety of developed composites. The results indicated that autoclaving at 6 bar/6hrs greatly returned the strength values for all hardened geopolymers, particularly the composite containing 50wt.%slag + 40wt.%fly-ash + 10wt.%sludge; its strength values were 22, 46 and 60 MPa at 20 °C/28 days, 80 °C/28 days and 6 bar/6hrs, respectively. The enthalpy change calculated by the DSC technique has the highest value (122.2 J/g) at 6 bar/6hrs, indicating the formation of additional hydration products. Hydrothermal treatment technology has proven its worth in immobilizing heavy metals in geopolymeric materials; curing at 6 bar/6hrs for specimen containing 30wt.%sludge decreased lead concentration by 95.2 and 97.8 % and cerium by 98.2 and 99.6 % in leachate solutions (HNO3 and CH3COOH, respectively). This may be attributed to the transformation of lead and cerium into insoluble Ce2Si2O7 and Pb3SiO5 as detected by XRD that are physically encapsulated in a cross-linked geopolymer structure. Furthermore, due to pore structure rearrangement that shifted to micro/mesoporous (2–50 nm) under the steam condition with a high BET surface area (31.7 m2/g) and low BJH average pore diameter (10.01 nm).

Enhancement of hydrogen clean energy production from greenhouse gas by in-situ hydrogen separation with a cobalt-silica membrane

Methane steam reforming is a representative reaction to convert carbon-rich fuel to carbon-free fuel. However, the thermodynamic equilibrium limits the conversion from methane to hydrogen. Separating hydrogen in-situ from hydrocarbon reforming reactions by inorganic membranes is an effective way to overcome the thermodynamic equilibrium, which improves the conversion of the reforming reactions and the efficiency of hydrogen production. Silica-based membrane, due to its size sieving effect, could separate hydrogen molecules from other larger gases at high temperatures, but the poor hydrothermal stability of silica in steam conditions remains a challenge for the application in hydrogen production. In this study, to improve the hydrothermal stability cobalt was doped in silica membrane precursors with varying ratios. After a series of characterizations by dynamic light scattering, Fourier Transform Infrared spectroscopy, X-ray diffraction, nitrogen adsorption and Scanning Electron Microscope, a cobalt-silica membrane with a cobalt/silicon ratio of 1/4 was fabricated by dip-coating technique. At 500 °C the membrane delivered helium permeance of 9.37 × 10−8 mol m−2 s−1 Pa−1, helium/nitrogen perm-selectivity of 258.48, and helium/carbon dioxide perm-selectivity of 242.19. The membrane was then employed in methane steam reforming for in-situ hydrogen separation to enhance methane conversion and hydrogen production. Raising the reaction temperature favors the performance of the membrane reactor, but temperature over 550 °C was still challenging due to hydrothermal stability issue. Increasing reaction pressure from 0 to 0.3 MPa favored methane conversion, but pressure over 0.4 MPa led to concentration polarization. Steam to carbon (S/C) ratio of 3 was suitable to avoid nickel/alumina catalyst coking and methane dilution. Reducing the gas hourly space velocity (GHSV) ensured sufficient residence time for methane and favored methane conversion. At T = 500 °C, Δp = 0.3 MPa, S/C = 3 and GHSV = 30 ml g−1 h−1, the membrane elevated the methane conversion from 45.36% (without membrane) to 83.71%. With a cobalt-silica membrane 4.32 ml min−1 of hydrogen was continuously produced with a purity of 82.12 vol% compared to 2.34 ml min−1 of hydrogen with a purity of 65.0 vol% in the case without a membrane. As expected, the micro-morphology of the cobalt-doped membrane after the 20-day steam reforming test showed little visible change in scanning electron microscope. The reduction of pore volume was only 15% as compared to 25% for pure silica material. This membrane demonstrated promising potential in the efficient production of hydrogen.

БАНКІВСЬКЕ ОБСЛУГОВУВАННЯ ЗОВНІШНЬОЕКОНОМІЧНОЇ ДІЯЛЬНОСТІ ПРОМИСЛОВИХ ПІДПРИЄМСТВ

Within the scope of banking services for the foreign economic activities of industrial enterprises, commercial banks keep funds in foreign currencies of such enterprises in current and deposit accounts, lend to the export and import activities of such enterprises, carry out international settlements, documentary, currency exchange operations, etc. The article examines the features of banking services for industrial enterprises at the current stage and defines its prospects and tools in the post-war period. It has been established that industrial enterprises try to keep cash balances in foreign currency in the most liquid form, so they either remain in current accounts or are converted into short-term deposits with a term of up to 1 year. Lending in foreign currency tends to decrease and is mostly short-term in nature. The main volume of loans in foreign currency is concentrated in the processing industry, in particular, half of them are in the food industry. As for long-term loans in foreign currency, they are concentrated on enterprises engaged in the supply of electricity, gas, steam and air conditioning, as well as enterprises of the metallurgical industry. Lending in US dollars is concentrated in the manufacturing industry, while lending in euros is predominant for enterprises engaged in the supply of electricity, gas, steam and air conditioning. There is practically no lending in other currencies. It is proposed to expand banking products of JSC "PUMB" for financing foreign economic activities of industrial enterprises through cooperation with international financial institutions, other domestic and foreign banks, leasing companies. Currently, servicing the foreign economic activities of industrial enterprises is not a priority area of activity, as JSC "PUMB" is reorienting itself to the retail segment and lending to agricultural producers, but in the conditions of post-war reconstruction, we believe that lending to industrial enterprises, in particular in a consortium with foreign banks and international financial organizations, should become one from strategic priorities.

ПРОМЫШЛЕННОЕ ПРОИЗВОДСТВО В СТРАНАХ ЕВРАЗИЙСКОГО ЭКОНОМИЧЕСКОГО СОЮЗА И СОСТОЯНИЕ ВЗАИМНОЙ ТОРГОВЛИ

Identifying the competitive advantages of the EAEU countries within the framework of mutual industrial and production cooperation, leveling emerging problems and searching for new opportunities are important for the active development of the economies of each state, using the existing potential, creating an independent fundamental and sustainable industrial base. According to the official statistics of the Eurasian Economic Commission, the total gross domestic product of the countries of the Eurasian Economic Union for the period from 2017 to 2022. increased by 44%, amounting to 2.6 trillion US dollars. The average annual GDP growth rate of the EAEU countries for the period from 2017 to 2022 amounted to about 1.5%. The highest share of industrial production in the gross domestic product (hereinafter referred to as GDP) in the countries of the Eurasian Economic Union (over 50%) is noted in the Republic of Belarus (88–89%), as well as in the Russian Federation (64%). The average level of industrial specialization in the structure of GDP is noted in Kyrgyzstan (44–46%), in Kazakhstan (42–47%), and also in Armenia (33–32%). On average, in the Eurasian Economic Union, the largest share in industrial production belongs to the manufacturing industry (64–65%), followed by mining (24–27%), electricity, gas, steam and air conditioning (7–9%), as well as water supply (1.7–2.0%). In order to integrate the joint industrial capabilities of the EAEU, to intensify work to create conditions for the development of union cooperation, an industrialization map was created in 2019. In modern conditions, it is necessary to strengthen innovative technological cooperation between the EAEU countries, joint production of machinery, machinery, equipment, increase the production of electrical equipment, metallurgical, leather and footwear, textile, knitwear and food industries in a closed cycle. In addition, it is important to conduct joint scientific research and develop measures to stimulate cooperation, including the creation of joint technological platforms, industrial clusters, the involvement of small and medium-sized businesses, the formation of cooperative chains for the production of joint products based on territorial and geographical opportunities.

Effect of steam conditioning on microbial safety and quality of pecans

This study evaluated application of steam treatment for inactivating Enterococcus faecium on in-shell pecans and its effect on kernel quality. In-shell pecans inoculated with Enterococcus faecium (7.28 ± 0.17 log CFU/g) were treated with steam at 70, 80 or 90 °C for 0–300s. Log-linear model was fitted to obtain D-value. Pecans steam-treated at 70, 80 or 90 °C for 5D were deshelled; kernels were stored in accelerated conditions (35 °C, 65%RH and 450–500lx for 25d) simulating 4 months storage at 22 °C. Peroxide value, moisture, aw, color, texture, and consumer acceptability were tested at 5d interval. At 80 and 90 °C, >5-log reduction was observed within 120s and 15s, respectively whereas, lower (P<0.05) reduction (4.28 ± 1.0 log CFU/g) was observed within 300s at 70 °C. The D-value at 70, 80 and 90 °C were 77s, 26s, and 4s, respectively. By 25d, 90 °C treatment delayed rancidity in pecans indicated by its significantly lower peroxide value than control. Steam treatment had no significant effect on the quality and consumer acceptability of pecans, instead consumers' willingness towards purchasing untreated pecans lowered after becoming aware of steam treatment's benefit on microbial safety. Steam treatment could be an efficient alternative conditioning method for pecans' safety and quality.

Numerical Modeling of Toe-to-Heel Air Injection and Its Catalytic Variant (CAPRI) under Varying Steam Conditions.

There are huge reserves of heavy oil (HO) throughout the world that can be energy-intensive to recover. Improving the energy efficiency of the recovery process and developing novel methods of cleaner recovery will be essential for the transition from traditional fossil fuel usage to net-zero. In situ combustion (ISC) is a less used technique, with toe-to-heel air injection (THAI) and catalytic processing in situ (CAPRI) being specialized novel versions of traditional ISC. They utilize a horizontal producing well and in the case of CAPRI, a catalyst. This paper aims to investigate the impact that injected steam has on both the THAI and CAPRI processes for the purpose of in situ HO upgrading and will help to bridge the gap between the extant laboratory research and the unknown commercial potential. This study also presents a novel method for modeling the THAI-CAPRI method using CMG STARS, proposing an in situ hydrogen production reaction scheme. THAI and CAPRI experimental-scale models were run under three conditions: dry, pre-steam, and constant steam. Starting from a reservoir American Petroleum Institute (API) of 10.5°, THAI reached an average API of ∼16 points, showing no increase in the API output with the use of steam injection. A decreased API output by ∼0.7 points during constant steam injection was achieved due to a high-temperature oxidation-dominant environment. This decreases the reactant availability for thermal cracking. The CAPRI dry run reached an API of 20.40 points and achieved an increased API output for both pre-steaming (∼21.17 points) and constant steaming (∼22.13 points). The mechanics for this increased upgrading were discussed, and catalytic upgrading, as opposed to thermal cracking, was shown to be the reason for the increased upgrading. Both processes produce similar cumulative oil (∼3150 cm3) during dry and pre-steamed runs, only increasing to ∼3300 cm3 with the constant steam injection during THAI and 3500 cm3 for CAPRI.

Patterns of embodied pollutant emissions along the global light industrial chain: A complex network perspective

With the upgrading of consumer goods and accelerating trade globalization, enormous amounts of pollution related to the light industry sector's production are transferred across borders along the global industrial chain, but their network patterns and evolution remain unclear. Here, we developed an analytical framework for trade-embodied pollutant emissions transfer (TPET) network by combining complex network theory and input– output theory to analyze the network of 16 light industries in 43 economies from 2000 to 2014. We revealed the critical economies, key industries, critical paths and their evolution trends. The light industry sector's total TPET was consistently large, but many factors (e.g., upgrading consumer goods, increasing trade volume, the 2008 financial crisis) caused large fluctuations. The network densities remained relatively high, with an obvious small-world property and significant centralization. Large economies (especially the world's top 10 economies with a total GDP exceeding US $1.86 trillion in 2014) were critical nodes due to their stable and dominant importance, but played opposite roles (i.e., net TPET importers vs. net exporters). Due to large differences in domestic demand, and environmental regulations, high-income economies (e.g., the U.S., and Germany) were the leading net TPET exporters, whereas low- or middle-income economies (e.g., China, Russia) were the dominate net importers; TPET therefore primarily flowed from high-income to low- or middle-income economies, with substantial growth over time. The electricity, gas, steam and air conditioning supply industry, the manufacture of other non-metallic mineral products, the manufacture of basic metals, and the fishing and aquaculture industry together accounted for 81.2 and 89.0% of total trade-embodied NOX and SOX emissions, respectively; they were thus key industries. To reduce emissions, critical economies should consume more environment-friendly products, strengthen technological innovation and pollution control in key industries, and expand environmental cooperation with other countries. Our results provide insights into the global light industry sector's TPET characteristics and reduction strategies. They also provide a reference for adjusting trade patterns and industrial structures.

High-Efficiency Carbon Fiber Recovery Method and Characterization of Carbon FIBER-Reinforced Epoxy/4,4'-Diaminodiphenyl Sulfone Composites.

Globally, the demand for carbon fiber-reinforced thermosetting plastics for various applications is increasing. As a result, the amount of waste from CFRPs is increasing every year, and the EU Council recommends recycling and reuse of CFRPs. Epoxy resin (EP) is used as a matrix for CFRPs, and amine hardeners are mainly used. However, no research has been conducted on recycling EP/4,4'-diaminodiphenyl sulfone (DDS)-based CFRP. In this study, the effect of steam and air pyrolysis conditions on the mechanical properties of re-cycled carbon fiber (r-CF) recovered from carbon fiber-reinforced thermosetting (epoxy/4,4'-diaminodiphenyl sulfone) plastics (CFRPs) was investigated. Steam pyrolysis enhanced resin degradation relative to N2. The tensile strength of the recovered r-CF was reduced by up to 35.12% due to oxidation by steam or air. However, the interfacial shear strength (IFSS) tended to increase by 9.18%, which is considered to be due to the increase in functional groups containing oxygen atoms and the roughness of the surface due to oxidation. The recycling of CFRP in both a steam and an air atmosphere caused a decrease in the tensile strength of r-CF. However, they were effective methods to recover r-CF that had a clean surface and increased IFSS.

Experimental investigation of heat transfer characteristics of water in a vertically–upward tube under ultra-supercritical pressure and ultrahigh-temperature conditions

Advanced ultra-supercritical (A-USC) steam power generation technology is characterized by main steam conditions of > 700 °C and > 35 MPa, enhanced cycle efficiency, and reduced environmental footprint, and is one of the important development goals of the thermal power plants today. However, scarce studies were conducted on the heat transfer characteristics of supercritical water (SCW) under A-USC operating conditions. An experimental platform to safely measure the heat transfer of SCW flowing in a vertical tube at temperature up to 760 °C and pressure up to 42 MPa was designed and built in this study. Experimental measurements of the heat transfer characteristics of SCW were performed on this platform in a wide range of temperature and pressure, up to a maximum bulk fluid temperature of 750 °C and a maximum pressure of 38 MPa. The effects of pressure, mass flux, and heat flux on the heat transfer characteristics of SCW in the ultrahigh enthalpy region (over 3200 kJ·kg−1) were then analyzed based on the experimental data. Results show that in the ultrahigh enthalpy region, the bulk fluid temperature and wall temperature increase approximately linearly with increasing bulk fluid enthalpy. The heat transfer coefficient decreases gently and then gradually stabilizes in the same range, with values in the range of 4–10 kW·m−2·K−1. In the ultrahigh enthalpy region, increasing the mass flux or decreasing the heat flux will improve the heat transfer performance. And at a pressure of > 35 MPa, increasing the pressure will improve the heat transfer performance moderately. By comparing with experimental data, the Gupta’s correlation has acceptable accuracy in predicting the heat transfer coefficient and inner wall temperature.

მრეწველობის განვითარების ხელშემწყობი ეკონომიკური პოლიტიკა საქართველოში

In connection with the transition to a market economy, the industrial industry inherited from the Soviet economy was almost completely dismantled. In 1990-1994, compared to the Soviet era, the production of industrial products decreased fivefold and the number of jobs fourfold (National Statistical Service of Georgia, 1995). Industrial products became uncompetitive in both domestic and foreign markets. The production of machines, devices, tools, electric machines, vehicles, products of light and partly food industry was stopped. Accordingly, the level of industrial production fell, the specific share of industry in the total domestic product decreased, and industrial ties were dissolved. All this led to the deindustrialization of the country. In 1999, the Ministry of Industry of Georgia developed: the Industrial Concept of Georgia and “Strategic Programs for the Development of Industrial Enterprises of Georgia in 2000-2005” in order to solve the extremely important tasks facing the industry of Georgia in the period of transition to a market economy and for their further development. However, they did not have a major impact on the revitalization of the industrial sector. In the years 2003-2012, the share of industry in the total domestic product decreased. By 2020, sales of industrial products and production increased significantly, but the pandemic had a serious impact on both indicators. In 2022, compared to 2020, sales decreased by 2.6 times and output by 2.9 times. The number of employees has increased slightly in recent years; there were no major changes during the pandemic. Wages increased 1.9x in 2022 compared to 2014, with a slight increase in the post-pandemic era. The largest sub-sector of the industry is manufacturing, the share of which has increased compared to previous years (2018 - 18.4%, 2019 - 18.4%, 2020 - 20%). The share of the mining industry has also increased slightly (2018 - 1.2%, 2019 - 1.4%, 2020 - 1.9%). This is followed by the supply of electricity, gas, steam and air conditioning, the share of which is characterized by a downward trend (2018 - 2.3%, 2019 - 2.1%, 2020 - 2.1%). The water supply is also characterized by a decreasing trend; Sewage, waste management and decontamination works (2018 - 0.7%, 2019 - 0.7%, 2020 - 0.6%) (Georgian National Statistics Service, 2021). The economic policy of the state plays an essential role in the development of industry. Institutes have been established in Georgia since 2012, the aim of which was, among other things, to promote the development of various branches of industry. To date, the Government of Georgia has implemented a number of programs in this direction. Specifically, Produce in Georgia, Partnership Fund, Industrial Development Group, Innovation and Technology Development Agency of Georgia, Startup Georgia. After the implementation of programs to support the industrial sector, there are some positive results both in terms of employment and business development. At the current stage of industrial development, the country should choose a model aimed at technological development and maximum growth of export potential. An industrial policy should be developed in the country, which will allow us to apply innovative approaches in the priority branches of industry. It is necessary to use such instruments of industrial policy as: innovations and technologies, education and skills, orientation to foreign trade, development of a mechanism to support priority industries, competitiveness and protection of competition. Based on the identified challenges in the area of ​​industry, recommendations for the implementation of an active industrial policy in short and long term periods were developed. Namely: the government's priority orientation of industrial development; paying special attention to the processing industry sectors that Georgia has the potential to produce; supporting the development of scientific fields; Determination of certain benefits for those investors who invest money in industrial production; State partnership with the private sector, manifested in the fight against bureaucracy, corruption and crime, creating favorable business conditions for entrepreneurs; Coordination between education - science - production should be implemented in the country. Much attention should be paid to basic scientific research, which does not require purely commercial returns in the short term, science should become a real productive force; Particular importance should be attached to the formation of such an entrepreneurial ecosystem that will contribute to the expansion of export-oriented production; Overcoming entry barriers in export markets. Keywords: Industry, sectoral structure of industry, export-import of industrial products, institutions implementing industrial policy. JEL Codes: L16, L52, L53, O25

Optimization of biogas-reforming conditions considering carbon formation, hydrogen production, and energy efficiencies

Hydrogen production from biogas requires energy efficiency. This study systemically compared pure biogas reforming, CO2-free biogas steam reforming, and biogas steam reforming. A comprehensive evaluation combining thermodynamic analysis, energy efficiency evaluation, and experimental validation was performed to compare the reaction types. Biogas steam reforming is the most attractive reforming reaction because it has the lowest SEC. In addition, the main parameters for the reaction conditions were investigated to optimize hydrogen production from biogas. The optimal conditions for the biogas steam reforming were determined as 750 °C and an H2O/CH4 ratio of 1.5. Finally, the previously developed Ni–MgO–CeZrO2 catalyst was tested under the optimized reaction conditions. Consequently, the catalyst showed high catalytic performance and was maintained for 30 h, even at a high GHSV of 36 000 h−1. This result implies that the optimized reaction condition derived by comparing the various indicators such as conversion of reactants, yield of products, energy consumption, and thermal efficiency is suitable for hydrogen production from biogas.

Optimization Effect of Metakaolin on Macro- and Micro-Mechanical Properties of Composite Cementitious Materials under Different Curing Conditions

To provide the theoretical basis for the engineering application of metakaolin as aluminum-rich pozzolanic ash materials, the promoting effect of metakaolin on the macro- and micro-mechanical properties of composite cement-based composite materials was explored under high-temperature steam and standard curing conditions. Analysis techniques, which involved thermogravimetric and nanoindentation coupled with scanning electron microscopy-energy dispersive X-ray spectroscopy, were used. To analyze the experimental data, the ACI empirical formula and the copula function were used. The correlation among the hydration degree of the MK-cement cementation system, the Al/Si of the C-(A)-S-H phase, and the nanomechanical properties of the C-(A)-S-H gel phase was investigated. According to prior research, the macroscopic mechanical properties and the substitution rate of the MK-cement composite cementitious system can be improved under high-temperature curing conditions in a short period, in which the optimum substitution rate of metakaolin is 20%. The ACI empirical formula was used to demonstrate the functional relationship between the metakaolin replacement rate, curing time, and compressive strength. The MK-cement cementation system can eliminate the defect phase, reduce the CH phase content, and then increase the C-(A)-S-H gel phase content and bulk density. The micro-mechanical properties of the C-(A)-S-H gel phase rises due to its phase content and Al/Si ratio. Furthermore, the copula function verifies the dependence of the nanomechanical properties of C-(A)-S-H gel and Al/Si.