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This paper is devoted to improve the design solution of combined thermo-photovoltaic systems which works in concentrated solar radiation. The main problem is ensuring the efficient heat removing from the photoreceiving surface of such systems and transferring this heat energy to liquid heat carrier. In case of using concentrated solar radiation with high density of energy onto the photoreceiving surface the problem of intensifying the heat exchange processes is critical for ensuring the efficient and long-term work of combined thermo-photovoltaic systems. Based on the analysis of thermal processes, the design of a heat exchange unit for a combined photovoltaic plant is proposed. The main design feature of proposed solution is microchannels made on the back plate of photoreceiving surface. It is shown that this design creates a transient regime of coolant flow, which allows efficient cooling of solar cells under conditions of concentrated solar radiation and potentially will allow to receive record values of heat exchange coefficient between the coolant and the upper plate of the radiator. An analysis technique using criterial hydrodynamic equations and numerical modeling were used; the results obtained in both cases are in good agreement. The efficiency, thermal and electrical characteristics of a combined photovoltaic system with solar radiation concentration have been assessed. Preliminary estimations have been made for the specific parameters of installed energy characteristics of a heat-electric power plant, which under AM1 conditions and 400 times the concentration of solar radiation for solar cells with an efficiency of 30 % have the following values: electrical power 650 W, thermal power 2370 W, total installed net power 3020 W, overall efficiency 87 % which are significantly higher than parameters achieved for existing solar power plants. [ABSTRACT FROM AUTHOR]

Green energy includes solar, wind, geothermal and other types of energy sources generation. The object of this research is solar concentrators. The problem to be solved is related to the development of the structure frame, especially for solar concentrators with flat triangular or square mirrors that approximate a parabolic shape surface. The essence of the investigation is developing and producing several prototypes of solar concentrators that have a low cost of materials but the devices were assembled by hand and therefore the manufacturing cost is sufficiently high. Therefore, it is important to reduce the cost through automation of the solar concentrator production process. To obtain better conditions for future automation, we need to reduce the number of metal structural elements of the solar concentrator. In this case, the automation problem is simpler for its realization. The results obtained are related to the improved solar concentrator structure that can be technologically simpler than the previous one and lighter in weight. The development of improved solar concentrator design and structure can help reduce the cost of assembly and accelerate the solar concentrator assembly process. In the case of mass production, they can be used in practice. The proposed solar concentrators can be used for different applications, for example, green buildings in rural areas, or chemical reactors to accelerate the chemical process of organic waste processing. Another application is to use solar concentrators in combination with agricultural fields. These solar concentrators can be used with small-scale thermal energy storage (TES). Using TES, it is possible to make power plants for green buildings. Small solar power plants can support all the energy demands of residential houses. [ABSTRACT FROM AUTHOR]

Optoelectronics focuses on light-emitting and light-detecting devices and investigation of the materials used for their fabrication. Usually, the light-emitting devices are lamps, LEDs, laser diodes and gainmedium lasers, while the light-detecting devices are represented by photodiodes, photovoltaic solar cells, photoresistors, phototransistors, etc. The above field also covers the studies of emission of materials under different stimuli and interaction of light with different types of materials, mostly semiconductors and metal nanostructures. A technological progress in the materials science has instigated development of nanomaterials and optoelectronic devices on their basis. They can be divided into two-dimensional (2D) quantum wells, films or sheets, 1D nanowires and 0D quantum dots. 2D graphene-like layered materials, quantum dots and metal nanoparticles for optoelectronic applications are the most investigated. As a matter of fact, a global scientific trend associated with the nanomaterials is currently transforming our technologies and industry and represents the most ambitious course of the present and future optoelectronics. [ABSTRACT FROM AUTHOR]

Стаття присвячена особливостям розвитку відновлюваної енергетики в Україні та світі. Спершу розглянуто тлумачення та наведено класифікаційні ознаки відновлюваних джерел енергетики. Особливу увагу приділено аналізу та особливостям запровадження альтернативних джерел енергії у світі на сучасному етапі. На основі аналізу визначено основні переваги запровадження «зелених» методів генерації енергії. Визначено, що частка відновлюваних джерел енергії в структурі електроенергії є закономірно високою в країнах зі сприятливими кліматичними умовами та великими гідроенергетичними ресурсами. Узагальнено перспективи подальшого запровадження ефективного механізму управління енергозбереження. Наведено основні шляхи переходу України на альтернативну енергетику у період відбудови після повномасштабної російсько-української війни.

В статті розглянуто актуальність впровадження альтернативних джерел енергії в готельний бізнес. Ця робота досліджує механізми впровадження таких джерел енергії, як сонячна, вітрова, та геотермальна на підприємствах готельного господарства. Аналізуються як технічні, так і економічні аспекти інтеграції, правові рамки та приклади успішних впроваджень у готелях світу. Особлива увага приділяється впливу на екологічність, зниженню оперативних витрат та поліпшенню іміджу готелів у очах споживачів. Дослідження має на меті оцінити потенційні переваги альтернативних джерел енергії для готельної індустрії, які включають зниження витрат на енергію, підвищення енергетичної незалежності, а також поліпшення загальної екологічної ефективності бізнесу. Також розглядаються основні рамки, що регулюють використання альтернативних джерел енергії на національному рівні, та приклади успішного застосування новітніх енергетичних технологій у готелях по всьому світу. Стаття включає рекомендації для готельних операторів щодо вибору, впровадження та оптимізації систем на основі альтернативних джерел енергії. Рекомендації базуються на аналізі поточних трендів, дослідженнях ефективності різних енергетичних рішень та їхньої відповідності до специфічних умов експлуатації в готельній індустрії.

The article examines the current state of development of the alternative energy market in Ukraine. An analysis of the energy market of Ukraine was made and the main factors stimulating the development of alternative energy were determined. These factors include legislative, economic, technological, administrative, geographic, and informational psychological factors. Changes in legislation related to the use of renewable energy sources are analyzed. A plan for the development of renewable energy sources in Ukraine is being considered. Today, most countries are trying to change their development scenarios to meet the ever-increasing energy needs. They do this by introducing new policies and focusing on alternative energy and energy efficiency issues. The transformation of energy markets is an important manifestation of modern energy trends. In this context, the achievements made within the framework of the Third Energy Package of the European Union regarding the creation of the European Union energy market should be particularly important. The analysis of the consequences of the transformation of energy markets in accordance with the Third Energy Package of the European Union allows to determine the main features and trends of the development of modern energy and to form connections between the subjects of the energy market in the next 10-20 years. All European countries have set targets for renewable energy. The European Union aims to become the world’s first climate-neutral continent by 2050.To achieve this goal, the European Union has launched its most ambitious package of measures, the European Green Deal, which aims to help people and companies in Europe achieve a sustainable green transition. In the light of the current pandemic, growing competition, globalization and ongoing European integration, research into the development of alternative energy is particularly important for Ukraine. Changes to the «green tariff» for wind and solar energy are presented. The paper shows that modern technological trends and improvement of energy efficiency and energy security of the country require changes in electricity production and are important for the country as a whole. [ABSTRACT FROM AUTHOR]

Today, the use of renewable energy sources (RES) is one of the main priorities of energy development for most of the developed countries of the world. In particular, the USA, Germany, Spain, Sweden, Denmark, and Japan plan to increase the share of RES in the total energy balance to 50% in the first half of the 21st century, but the number of countries, cities and individual communities that aim to ensure energy consumption through RES is steadily increasing, and some of them aim to switch to RES at the level of 100%. The energy strategy of Ukraine foresees that by 2035 the share of RES in Ukraine will be 25%. But in view of the destruction caused by the enemy to thermal generation facilities and power supply networks of Ukraine, the state must strengthen the development of RES and accelerate the energy transition: this is a matter of national security and security of electricity transmission, for the solution of which Ukraine must fully use its scientific and technical potential, in which the main role is given to scientific institutions that deal with the development of renewable energy systems. The flagship among such scientific institutions is definitely the Institute of Renewable Energy of the National Academy of Sciences of Ukraine, which has absorbed the experience and knowledge of several generations of RES scientists and created a unique research and experimental base for realizing their potential. The article presents factual materials regarding the areas of activity, scientific potential, achievements, as well as the history and prerequisites for the establishment of the Institute of Renewable Energy of the National Academy of Sciences of Ukraine. This information is about the management of the Institute, its structure by departments and their tasks. [ABSTRACT FROM AUTHOR]

Water is a very important component for humans in everyday life. The need for clean water is currently increasing, especially for people living in coastal areas, this is because the water still contains salt and smells. Solar radiation energy is an alternative energy source. However, its use has not been utilized optimally, as science develops, solar energy has become an object of research, and one discovery of the use of solar energy is distilling sea water using solar energy. Under these conditions, research will be carried out on clean water distillation equipment, to see and analyze the productivity of water produced by clean water distillation equipment that uses zinc-coated steel tanks. The results obtained do not rule out the possibility that this distillation device with a zinc-coated steel tub can be used to reduce the problem of lack of clean water, especially as it is known in coastal areas where solar energy sources are not only abundant but also very abundant, but the availability of clean water is limited. still very minimal. So that existing solar energy sources can be used as an energy source in distillation equipment to produce clean water. From these results, the productivity of the water produced can be seen that solar radiation has a great influence on increasing the efficiency of the distillation equipment. Then the results of condensate water production and efficiency produced by a tool with a one-sided cover glass are greater than a tool with a double-sided cover glass. [ABSTRACT FROM AUTHOR]

В галузі холодильної техніки вирішення задач ресурсо- та енергозбереження може бути досягнуто за рахунок використання відновлювальних джерел енергії, зокрема сонячної енергії. Об'єктом аналізу було обрано абсорбційні водоаміачні холодильні машини (АВХМ), що працюють від сонячної енергії. Аналіз режимних характеристик АВХМ показав, що основні проблеми, які треба вирішити при їх використанні в системах отримання води наступні: по-перше, розробити конструкції АВХМ з повітряним охолодженням теплорозсіювальних елементів; по-друге, запропонувати цикл, який можна було б реалізувати в умовах тропічних температур зовнішнього повітря на рівні температур традиційних водяних сонячних колекторів (80-100 °С). Виконано аналіз сучасного стану енергозберігаючих розробок холодильних машин абсорбційного типу. Показано, що АВХМ можуть вирішувати задачі штучного охолодження в діапазоні температур від -30 °С (тривале низькотемпературне зберігання продуктів тваринного та рослинного походження) до +5…7 °С (кондиціювання повітря) з використанням сонячної теплової енергії. При цьому вирішуються задачі усунення несприятливого техногенного впливу робочого тіла (водоаміачного розчину) на довкілля. Для створення енергозберігаючих схем АВХМ перспективно використовувати холодоакумулюючі матеріали, електронні системи автоматичного керування, що забезпечують мінімальне енергоспоживання за зміни умов експлуатації (добові коливання температур сонячної енергії та атмосферного повітря). Підвищення енергетичної ефективності зовнішніх та внутрішніх процесів тепломасообміну в АВХМ може бути досягнуто за рахунок, відповідно, застосування теплових труб, двофазних термосифонів, зниження контактного термічного опору в зонах відведення та підведення тепла та оптимізації процесів циркуляції парогазової суміші в елементах парогазового контуру

Introduction. Increasing vehicle numbers, coupled with their increased consumption of fossil fuels, have drawn great concern about their detrimental environmental impacts. Alternative energy sources have been the subject of extensive research and development. Due to its high energy density, zero emissions, and use of sustainable fuels, the battery is widely considered one of the most promising solutions for automobile applications. A major obstacle to its commercialization is the battery's high cost and low power density. Purpose. Implementing a control system is the primary objective of this work, which is employed to change the energy sources in hybrid energy storage system about the load applied to the drive. Novelty. To meet the control objective, a speed condition-based controller is designed by considering four separate math functions and is programmed based on different speed ranges. On the other hand, the conventional/intelligent controller is also considered to develop the switching signals related to the DC-DC converter’s output and applied the actual value. Methods. According to the proposed control strategy, the adopted speed condition based controller is a combined conventional/intelligent controller to meet the control object. Practical value. In this work, three different hybrid controllers adopted speed condition based controller with artificial neural network controller, adopted speed condition based controller with fuzzy logic controller, and adopted speed condition based controller with proportional-integral derivative controller are designed and applied separately and obtain the results at different load conditions in MATLAB/Simulink environment. Three hybrid controller’s execution is assessed based on time-domain specifications. [ABSTRACT FROM AUTHOR]

In the field of refrigeration technology, resource and energy saving can be solved through the use of renewable energy sources, in particular solar energy. Absorption water-ammonia refrigerating machines (AWRM) operating on solar energy were chosen as the object of analysis. The analysis of the mode characteristics of AWRM showed that the main problems that must be solved when using them in water production systems are as follows: first, to develop AWRM structures with air cooling of heat dissipating elements; secondly, to propose a cycle that could be implemented in conditions of tropical outdoor air temperatures at the temperature level of traditional water solar collectors (80-100 °C). An analysis of the current state of energy-saving development of absorption-type refrigerating machines was performed. It has been shown that AWRM can solve the tasks of artificial cooling in the temperature range from -30 °С (longterm low-temperature storage of products of animal and plant origin) to +5...7 °С (air conditioning) using solar thermal energy. At the same time, the tasks of eliminating the adverse man-made impact of the working fluid (aqueous ammonia solution) on the environment are solved. It is promising to use cold-accumulating materials, electronic automatic control systems, which ensure minimum energy consumption during changes in operating conditions (daily temperature fluctuations of solar energy and atmospheric air) to create energy-saving schemes of AWRM. Increasing the energy efficiency of external and internal processes of heat and mass exchange in the AWRM can be achieved due to, respectively, the use of heat pipes, two-phase thermosyphons, reduction of contact thermal resistance in the heat removal and supply zones, and optimization of the steam-gas mixture circulation processes in the elements of the steam-gas circuit. [ABSTRACT FROM AUTHOR]

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The use of solar energy in current conditions is one of the most affordable and popular energy-saving technologies that allows to significantly increase the efficiency of heat supply due to the fact that the energy obtained from the Sun is the cheapest and technologically available. The work considers the issue of using solar heat supply systems for heating needs of private houses, office premises and industrial premises. A classification of existing types of solar collectors is provided. A general analysis of the construction, principle of operation and composition of flat and vacuum solar collectors is given. The main thermophysical parameters that determine the efficiency of the solar system are substantiated. An analysis of the efficiency of flat and vacuum solar collectors for heating water in the hot water supply and heating system of buildings was performed. A patent search and systematized innovative solutions that increase the efficiency of the solar system have been conducted. General shortcomings of all heliosystem designs and directions of efforts of inventors are established. It is concluded that in order to improve the efficiency of solar heat conversion systems, work algorithms and high-quality adjustment of control controllers and their use by regulators must play a significant role. Their main function is to control the thermophysical parameters of the heliosystem and automatically make a decision on the control of electronic valves in order to ensure the optimal temperature of the coolant in all circuits. It is justified that further research into the implementation of multi-circuit systems for obtaining thermal energy from solar radiation in combination with other sources of obtaining thermal energy and an effective system for accumulating the received heat has a perspective. [ABSTRACT FROM AUTHOR]

Одним із найважливіших завдань в досяжному майбутньому є ще більше розвинення технологій, що дозволяють вилучати воду з повітря, причому безпосередньо на місці, де вона необхідна. Найбільші перспективи мають методи, пов'язані з роботою автономних генераторів штучного холоду, які гарантовано забезпечують температуру охолодження повітря нижче точки роси – установок отримання води з атмосферного повітря на базі абсорбційних водоаміачних термотрансформаторів (АВТТ), що працюють від джерела низькопотенційного тепла – сонячної енергії. З урахуванням аналізу відомих технічних рішень запропоновано схеми систем життєзабезпечення житлового будинку, на прикладі кліматичних умов Одеської області, з використанням традиційних та відновлюваних джерел енергії. Запропонована базова схема, яка є удосконаленою технічною пропозицією універсальної системи опалення, охолодження (кондиціювання) та отримання води з атмосферного повітря на базі традиційних та відновлюваних джерел енергії (сонячних колекторів). Для рішення задач отримання холоду була запропонована оригінальна конструкція АВТТ з бустер-компресором після генератора, яка захищена патентними документами України. Включення в схему бустер-компресора дозволяє суттєво розширити робочі характеристики у частині рівня температур гріючого джерела. Так, наприклад, він необхідний у схемах із сонячними колекторами з водою у якості теплоносія, де температура не перевищує 100 °С. Доведено, що для умов роботи випарника при температурі 5 °С спостерігається зниження електричної потужності в системах АВТТ з бустер-компресором, порівняно з парокомпресорними аналогами, у 3,3 рази при експлуатації в помірному кліматі і у 2,4 рази – у тропічному кліматі. У результаті розрахунку було визначено в практичному діапазоні параметрів експлуатації систем з сонячними колекторами енергетично ефективний режим для бустер-компресора. Для систем при експлуатації в помірному кліматі це: тиск кипіння в генераторі 1,0 МПа і температура 80 °С. Запропонована також автономна холодильна установка на базі безнасосного абсорбційного холодильного агрегату. Виконано аналіз кліматичних умов одеського регіону. До уваги взяли найпівнічніше місто – Подольськ, місто у середині регіону – Одеса, та місто на півдні –Ізмаїл. При проведенні аналізу середньомісячної температури було виявлено найліпші місяці для утворення конденсату: квітень – жовтень. Було виявлено, що місто Ізмаїл є найвигіднішим для утворення конденсату, та отримання води з атмосферного повітря, у зв’язку з південними координатами регіону

У даний час зростає інтерес до відновлювальних джерел енергії (ВДЕ). Незважаючи на це, в енергетичних системах високої продуктивності переважно використовуються вугілля, нафта, природний газ, а також енергія, що виробляється гідроелектростанціями та атомними електростанціями. Перші три джерела сформували так звану вуглецеву енергетику, якій притаманні два основні недоліки: обмеженість ресурсів та збільшення викидів СО2 у навколишнє середовище, незважаючи на вимоги Кіотського протоколу. Більшість ВДЕ характеризуються нерівномірним виробництвом та споживанням енергії, тому необхідно забезпечувати також її зберігання. Можна зауважити, що чим більше виробляється електроенергії вітру і сонця, тим сильніше виявляється потреба в системах накопичення і зберігання цього виду енергії. Сприятливим фактором для впровадження ВДЕ при цьому є різке зниження вартості одиниці встановленої потужності, яка включає в себе експлуатаційні і капітальні витрати. У статті розглядаються відносно нові типи ВДЕ, які дають змогу зберігати енергію у вигляді води (PSHE), компримованого повітря (CAES) та кріогенних рідин – повітря та азот (CES). За допомогою цього способу можна реалізовувати всі процеси виробництва, розподілу, зберігання та застосування електричної енергії у різні періоди часу. Розглянуто питання створення ефективного обладнання для тривалого зберігання тепла, що виробляється з електроенергії, яка виробляється сонячними панелями та вітрогенераторами. Тепло, яке отримується у такий спосіб, можна довго зберігати у теплоізольованих контейнерах, що заповнюються базальтовою крихтою. Актуальність цих досліджень підтверджується міжнародним енергетичним агентством: «ВДЕ вже є другим за величиною джерелом електроенергії у світі, але їх використання все ще необхідно прискорювати, якщо ми хочемо досягти довгострокових цілей у галузі клімату, якості повітря та доступу до енергії»

У статті наведено результати прогнозування потужності на виході сонячної панелі методом поліномів різного степеня. Прогнозування кількості електроенергії, що виробляється сонячною електростанцією, є насамперед передбаченням кількості сонячного випромінювання, отриманого сонячною панеллю, що в свою чергу залежить від умов та параметрів навколишнього середовища. Розрахунок проводився на основі даних сонячної інсоляції з лабораторії LARES, що знаходиться в місті Загреб. Дані були взяті за 04.05.2019 – 05.05.2019 з дискретністю 1 хвилина. Для того, щоб виконати прогноз, значення сонячної інсоляції були переведені в потужність на виході сонячної панелі. Для прогнозування обрано горизонт прогнозу в 1 годину та 1 добу. Проведено апроксимацію даних за допомогою поліномів різних степенів. Представлені криві зміни реальних та прогнозованих значень потужності на виході сонячної панелі. Точність прогнозування оцінювалось за допомогою середньої відносної похибки. Наведено результати корекції прогнозованих значень потужності методом Хойна.

Purpose. Creation of highly efficient evaporators based on materials with capillary properties and energy of solar radiation. Methodology. The processes of evaporation from the surface of cotton, silk and linen fabrics were studied in the natural environment. The necessary equipment in the simplest case is a cloth, fixed vertically and immersed in the lower end of the concentrate. Tap water and NaCl solutions with a concentration of 100 g/dm3 were used as model solutions. Findings. Among modern methods of liquid waste disposal in the form of concentrates from various industries, thermal methods have become the most widespread, which are not critical to the chemical composition of concentrates and allow converting them into a solid state. On the other hand, thermal methods require significant energy costs, which makes the accumulation and storage of concentrates more cost-effective, despite environmental problems. Therefore, research in the field of reducing energy costs through the use of solar energy is extremely important today, especially in the context of global warming. Since it is difficult to raise the ambient temperature with large concentrates, we have proposed to increase the evaporation rate by increasing the evaporation area. To carry out this process, fabric with capillary properties were selected, due to which the liquid phase is able to rise to significant heights. In some cases, the intensity of evaporation can be increased by several orders of magnitude. Originality. The paper substantiates the possibility of using this method for evaporation of liquids and crystallization of substances contained in concentrates. The influence of temperature on the height of liquid rise through fabric capillaries and the influence of salt concentration on the intensity of their crystallization are studied. The influence of the fabric thickness on the crystallization intensity of the constituent concentrates is studied. Several designs of crystallizers are proposed, which allow increasing the efficiency of the evaporation process, automating the stages of solid phase removal and fabric regeneration. Practical value. The proposed designs of evaporators are ready for application in industrial enterprises and are especially effective in areas with warm temperatures throughout the year. [ABSTRACT FROM AUTHOR]

Estimates of the efficiency of solar installations in the Sun tracking mode presented in the literature are often ambiguous due to nonidentical comparison criteria and irradiation conditions. It is pro-posed to evaluate this characteristic systematically by two indicators - orientation and energy. The first is numerically equal to the current value of the cosine of the illumination angle of the receiving surface. And the second - the daily exposure of the tracking surface, attributed to the maximum value with ideal tracking of the Sun by a biaxial rotary device. Both indicators are calculated under the assumption of irradiation with three streams of solar energy in clear skies, which change during the day according to the model of the European Solar Radiation Atlas (ESRA). posed to evaluate this characteristic systematically by two indicators - orientation and energy. The first is numerically equal to the current value of the cosine of the illumination angle of the receiving surface. And the second - the daily exposure of the tracking surface, attributed to the maximum value with ideal tracking of the Sun by a biaxial rotary device. Both indicators are calculated under the assumption of irradiation with three streams of solar energy in clear skies, which change during the day according to the model of the European Solar Radiation Atlas (ESRA). The relationships between the fluxes of solar radiation at different atmospheric states are taken into account by the Linke turbidity factor. The unit of comparison of the efficiency of uniaxial tracking is the daily exposure of the surface the biax ial tracking device, the angle of illumination of which during the day is zero. Four variants of estimation of efficiency concerning direct and full streams of solar radiation at two variants of distribution of brightness of the sky - isotropic and non-isotropic in the Hay-Davies model approximation are considered. The simulation results are presented in tabular and graphical forms. [ABSTRACT FROM AUTHOR]

This paper presents new scientific results of experimental studies that refute the generally accepted fact that the coat solely protects animals from the effects of solar energy. The purpose of this study was to confirm the fact of the spread of optical radiation energy under the animal's skin along individual hairs, as light guides. The authors of this study experimentally determined the optically conductive structure of an individual wool hair, the components of the transmission parameter of an individual wool hair, namely the coefficient of light transmission inside the wool hair, the coefficient of attenuation of internal light transmission by the substance of the wool hair, the coefficient of losses in the middle of the cylinder of the wool hair due to the beam scattered in the internal structure and the refractive index of its outer shell. Based on the use of methods of photometry and geometric optics, theoretically substantiated and experimentally obtained results regarding the establishment of a mathematical dependence of the total amount of optical radiation energy entering the hair cylinder on the value of the angle of incidence of the beam on the surface of the hair, the cleanliness of the inner core of the cylinder structure, the length of the light-conducting section to the surface of the skin, as well as the refractive index of its outer shell. Based on the results of experimental studies, mathematical dependencies were obtained that describe the spectral light-conducting properties of an individual hair, as well as the distribution of energy emitted in the thickness of the skin along the entire length from the point of penetration into the hair and to the follicle -- the place of use of optical energy in photobiological processes. The obtained results of experimental studies of the passage of optical radiation energy along the length of a single hair into the body of an animal are of practical importance for photobiologists investigating the effect of optical radiation from the Sun on biological objects of animal origin [ABSTRACT FROM AUTHOR]

Показано, що одним з відомих напрямків часткової компенсації дефіциту води можуть бути системи отримання води з атмосферного повітря, в яких холодильні машини або агрегати забезпечують температуру нижче температури точки роси. При виборі типів холодильних машин або агрегатів для цих систем перспективним може бути використання сонячної енергії, зокрема, сонячних колекторів, широко використовуваних в світі для опалення в холодний і перехідний період року, а також для господарських і санітарно-гігієнічних потреб. Тут великі перспективи мають абсорбційні водоаміачні системи, які на відміну від бромістолітієвих аналогів мають можливість працювати з повітряним охолодженням теплорозсіювальних елементів. У той же час використання абсорбційних водоаміачних холодильних систем в системах отримання води з атмосферного повітря утруднено через недостатній рівень температур джерела сонячної енергії. Об'єктом досліджень є модернізований абсорбційний холодильний агрегат (АХА), в якому проводиться додаткове очищення слабкого водоаміачного розчину (ВАР) шляхом випаровування частини аміаку в парогазову суміш. Розроблено методику розрахунку для визначення питомих теплових навантажень на елементи конструкції при заданих параметрах робочого тіла в характерних точках (вхід-вихід елементів) з подальшим визначенням енергетичної ефективності холодильного циклу АХА. Було показано, що склад інертного газу не впливає на ефективність циклу. Заміна водню гелієм призводить лише до зростання кількості циркулюючого газу в 2 рази, що ускладнює роботу контуру природної циркуляції між абсорбером і випарниками аміаку і розчину. Максимальну ефективність має АХА, що працює в діапазоні температур охолодження – від -18 до +12 °С. При цьому визначальний вплив на енергетичну ефективність надає температура кінця випаровування. Результати енергетичного аналізу АХА дозволили сформулювати ряд рекомендацій для розробників. Відзначено, що необхідні для розрахунку випарника розчину вихідні дані можна отримати в результаті моделювання процесів тепломасообміну в наближенні адіабатності процесів

Copyright of Refrigeration Engineering & Technology is the property of Odesa National University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Metallophysics & Advanced Technologies / Metallofizika i Novejsie Tehnologii is the property of G.V. Kurdyumov Institute for Metal Physics, N.A.S.U and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

One of the most important tasks is to further develop technologies that allow you to extract water from the air, and directly where it is needed. The most promising methods are related to the operation of autonomous artificial cold generators, which are guaranteed to provide the cooling temperature of air below the dewpoint – units for obtaining water from atmospheric air based on absorption ammonia thermal transformers (ATT), operating from low potential heat – solar energy. Taking into account the analysis of known technical solutions, the following schemes of life support systems of a residential building are proposed, on the examples of climatic conditions of Odessa region with the use of traditional and renewable energy sources. The basic scheme which is the improved technical offer of universal system of heating, cooling (conditioning) and reception of water from atmospheric air on the basis of traditional and renewable energy sources (solar collectors) is offered. To solve the problem of obtaining cold, the original design of ATT with a booster compressor after the generator was proposed, which is protected by patent documents of Ukraine. The inclusion of a booster compressor in the circuit allows to significantly expand the operating characteristics in terms of the temperature level of the heating source. So, for example, it is necessary in schemes with solar collectors with water as the heat carrier where temperature does not exceed 100 °C. It is proved that for the conditions of evaporator operation at a temperature of 5 °С the reduction of electric power in ATT systems with a booster compressor, in comparison with steam compression analogues, is 3,3 times in operation in temperate climates and 2,4 times in tropical climates. As a result of the calculation, an energy-efficient mode for the booster compressor was determined in the practical range of operating parameters of systems with solar collectors. For systems in operation in temperate climates it is: boiling point in the generator of 1,0 MPa and temperature of 80 °C. An autonomous refrigeration unit based on a pump-free absorption refrigeration unit is also proposed. The analysis of climatic conditions of the Odessa region was performed. The northernmost city – Podolsk, the city in the middle of the region – Odessa, and the city in the south – Ismail were taken into account. The analysis of the average temperature for the places revealed the best months for the formation of condensate: April-October. It was found that the city of Ismail is the most favorable for the formation of condensate and water from the atmosphere, due to the southern coordinates of the region. [ABSTRACT FROM AUTHOR]

Nowadays there is an increasing demand for alternative energy sources used in the national economy, industry and everyday life. Solar energy is one of the most promising alternatives to traditional methods of electricity generation. The actual problem is the development of economic and renewable technologies in the production of photovoltaic converters (PVC) based on poly- and monocrystalline silicon. The trends in the creation of the most complex electronic devices based on multilayer epitaxial structures are clearly manifested. At the same time, very high requirements are imposed on the electrophysical properties and perfection of the structure of each layer, the problems of creating perfect and sharp p-n junctions and heteroboundaries on large areas of epitaxial compositions are posed. The article proposes new technological aspects of the formation of silicon nanostructures with transparent coatings, which will significantly improve the quality of PVC on their basis with an efficiency of up to 27 % that will give impetus to the formation of new energy systems. [ABSTRACT FROM AUTHOR]

The paper considers photovoltaic (PV) systems, which are one of the most promising systems of renewable energy sources. The electricity produced by PV panels has great potential, but also has technological shortcomings that do not allow obtaining maximum efficiency. The aim of our study is to reduce technological shortcomings, which will increase the service life of PV systems and the amount of electricity received. The obtained model allows considering the technical parameters that take into account the heat loss and thermal resistance of the absorber plate. The results of the calculations performed coincide with the experimental data. The main aim of the proposed research is to consider a method for increasing the efficiency and lifetime of PV systems. This article briefly presents theoretical methods for increasing the efficiency of such systems, as well as increasing the service life, by simulating the cooling parameters of the absorber surface of such systems and tracking the maximum power. Modeling and the obtained theoretical model will allow in the future to select the most suitable technical solutions for the maximum energy output of PV systems for various design solutions. [ABSTRACT FROM AUTHOR]

Introduction. This paper deals with the specific aspects of insolation of the terrestrial surface in the southern regions of Ukraine, namely the clearness index and diffuse fraction of the atmosphere. The study was based on satellite data of the average daily insolation and total cloudiness in the nodes of the two-degree grid for the domain with coordinates 48°-45° N and 29°-39° E for the period of 1981-2020. The purpose of article. The purpose was to develop statistic models of horizontal surface insolation for various locations of study domain. Main focus was put on special characteristics in conditions of fixed cloudiness. Satellite data for the summer season had been used to evaluate the maximum solar energy potential of Ukraine. Methods. Application statistical analysis and means of cartographic data layout were used in the paper. Results. It was found that with the highest (more than 50%) frequency the total cloud cover can be characterized by the atmosphere clarity 0.7 ÷ 0.9 corresponding to a clear sky condition. The significance of irradiation of the terrestrial surface with diffuse solar radiation has been observed, with the share of such radiation in the global irradiation (diffuse ratio) being closely inversely related to the clearness index (correlation about -0.97). In turn, both diffuse ratio and clearness index are statistically dependent on the sky clarity, that allowed deriving analytical functions - diffuse ratio and clearness index - of the sky clarity, which appeared to be Sand Z-shaped curves, respectively. Dispersion of the clearness index (kt ) and the diffuse fraction (kd ) values and the strength of their statistical relationship significantly depend on the sky clarity. The empirical distribution of the two-dimensional random variable (kt ;kd ) well meets the Gaussian distribution, and the obtained dispersion ellipses allowed calculating the confidence intervals of the two-dimensional random variable (clearness index: diffuse fraction) for a given confidence level. The spatial distribution of the clearness index and diffuse fraction of the atmosphere in the southern regions of Ukraine revealed a significant dependence of these indices on the latitude and the type of underlying surface. At the end of the summer a seasonal effect has been observed in the spatial distribution of the clearness index and diffuse fraction, which can be explained by the specific seasonal features of atmospheric circulation, caused by the spreading out of the eastern ridge of the Azores anticyclone and the general situation with blocking developments in the Atlantic-European sector of the Northern Hemisphere. The scientific novelty. Correlation and regression models of special insolation characteristics in conditions of various cloudiness that are represented in this paper are new to Ukraine. Analysis of two-dimensional random value spread (clearness index: cloudiness index) allowed to assess probabilities of integral solar radiation flows. The obtained analytical membership functions for monthly average values of clearness and cloudiness indices depending on the level of sky clarity proved to be applicable for determining respective indices for daily time scale. Practical significance. The obtained results are important for comprehensive assessment of the solar / photovoltaic resources of southern regions of Ukraine. Specifically, analytical dependences have practical values for the purpose of forecasting direct and diffuse solar radiation in various time scales based on publically available global records of solar radiation. [ABSTRACT FROM AUTHOR]

Розроблені принципові схеми багатофункціональних сонячних систем осушення повітря, теплопостачання (гарячого водопостачання та опалення), холодопостачання та кондиціювання повітря на основі відкритого абсорбційного циклу з прямою (безпосередньою) регенерацією абсорбенту. Такі системи базуються на попередньому осушенні повітряного потоку й наступному випарному охолодженні середовищ у сонячних холодильних системах (СХС) и термовологісної обробки повітря в сонячних системах кондиціювання повітря (ССКП). Авторами використовувався принцип двоступінчастої регенерації абсорбенту. Сонячна система складається з автономних осушно-охолоджувальних блоків, причому кожний ступінь регенерації замкнений на відповідний ступінь абсорбера-осушувача повітря, що дозволяє збільшувати концентрацію абсорбенту від ступеня до ступеня (у діапазоні можливих концентрацій використовуваного розчину бромистого літію LiBr). Розроблені принципові рішення для нового покоління газо-рідинних сонячних колекторів, що забезпечують безпосередню (пряму) регенерацію розчину абсорбенту. Робота тепломаcообмінних апаратів, що входять в осушувальний і охолоджувальний контури абсорбційних систем, базується на принципі плівкової взаємодії потоків газу й рідини з використанням багатоканальної структури із полімерних матеріалів для створення насадки. Попередній аналіз можливостей багатофункціональних сонячних абсорбційних систем виконувався на основі експериментальних даних авторів та моделювання процесів тепломасообміну в основних елементах систем, відносно завдань кондиціювання повітря (ССКП). Показано, що практично для будь-яких, «важких» параметрів зовнішнього повітря вирішення завдань забезпечення його комфортних параметрів може бути виконано без використання традиційної парокомпресорної техніки. Розроблені сонячні системи ССКП відрізняються малим споживанням енергії й екологічною чистотою.

This research article represents a method of the intellectual power management optimization that integrates renewable sources with battery backup using fuzzy technique. The developed fuzzy controller monitors the continuous variations of the energy of selected renewable sources and load demand for the energy management systems. Then FLC shifts to provide electricity into the load allows for fuzzy instructions for efficient power supply. Here, the fuzzy rule has been developed from human thinking with the highest priority of renewable energy to electric load in any time of a day. When the load demand is full, the excess power will be charged to the battery. Again, if at any time of the day, the power generation from renewable energy is less, then the stored electricity in the battery will act as a backup system to load. Lastly, if at any time of the day the load demand and the condition of the battery charge are full, even if the renewable energy remains, it is arranged to be given to the dummy load. The system has been built where electricity has not yet been reached. The simulation results show that a properly constructed fuzzy rule can work 24 h a day for any difficult situation where the nonlinear function has been used. The whole system is very environmentally friendly where no harmful gas is emitted. [ABSTRACT FROM AUTHOR]

Solar energy is one of the most effective resources because of its cheap source and its reliability to sustain. The best way to attain the maximum possible efficiency from solar panels is to use tracking devices. Solar tracking will contribute significantly to increasing the efficiency of energy collection from the PV panels. Trackers can either be the single- or dual-axis. In this work, we have presented the designing and performance analysis of the dual-axis solar tracking system in comparison to the fixed panel system. We have determined the output power generated by a dual-axis solar tracking system is more than the fixed panel system. The outcome of the dual-axis solar tracking system has been analyzed and compared with the fixed panel system has been highlighted and it has shown better performance in terms of voltage, current, power and battery charging capabilities. Dual-axis trackers give more energy as it tracks sunlight in both the direction. Hence it is more efficient than fixed panel. [ABSTRACT FROM AUTHOR]

Currently, there is a growing interest in renewable energy sources (RES). Despite this, high-performance energy systems mainly use coal, oil, natural gas, as well as energy produced by hydroelectric and nuclear power plants. The first three sources formed the so-called carbon energy, which has two main disadvantages: limited resources and increased CO2 emissions into the environment, despite the requirements of the Kyoto Protocol. Most renewable energy sources are characterized by uneven energy production and consumption, so it is necessary to ensure its storage. It can be noted that the more electricity is produced by wind and solar, the stronger the need for systems for the accumulation and storage of this type of energy. A favorable factor for the introduction of renewable energy sources is a sharp decrease in the unit cost of installed capacity, which includes operating and capital costs. The article considers relatively new types of renewable energy sources, which allow to store energy in the form of water (PSHE), compressed air (CAES) and cryogenic liquids - air and nitrogen (CES). With this method you can implement all the processes of production, distribution, storage and use of electricity in different periods of time. The issue of creating efficient equipment for long-term storage of heat produced from electricity produced by solar panels and wind turbines is considered. The heat obtained in this way can be stored for a long time in heat-insulated containers filled with basalt crumb. The relevance of these studies is confirmed by the International Energy Agency: "Renewable energy sources is already the second largest source of electricity in the world, but their use still needs to be accelerated if we want to achieve longterm goals in climate, air quality and energy access". [ABSTRACT FROM AUTHOR]

This paper outlines the prospect of obtaining water from atmospheric air by cooling it to the dew point temperature using refrigeration machines in order to partially reduce water scarcity in the arid regions of our planet. To minimize energy costs in the systems for obtaining water from atmospheric air, it is proposed to utilize solar energy with absorption refrigeration units (ARUs) acting as a source of artificial cold. The characteristic thermodynamic processes have been analyzed in a modernized ARU, capable of working at a lower thermal energy source’s temperature than its analogs. The possibility has been studied to reduce the temperature of the heat source by including a solution vaporizer in the ARU scheme. The analysis involved an authentic method based on the balance of specific streams of ARU working body components and actual boundary conditions at characteristic points of the cycle. A limit was shown for the level of a minimum boiling temperature in the ARU generator (from 90 °C) when the systems for obtaining water from atmospheric air are operated under current climatic conditions. The simulation of heat-and-mass exchange processes during contact interaction between a steam-gas mixture and ammonia water solution was carried out. Based on variant calculations, it has been shown that the proposed ARU structure with an adiabatic solution vaporizer could work as part of systems to obtain water from atmospheric air at a hot spring temperature above 100 °C and constructively enough fits into the element base of standard models. It has been proposed to use two types of solar thermal energy sources to operate ARU. In a tropical climate, with vacuum solar collectors or solar energy hubs; in a temperate climate zone, with solar collectors with water as a heat carrier [ABSTRACT FROM AUTHOR]

In this paper, preparation of PVP/PAA/MnO2 nanofluid and studying its structural and optical properties for solar collectors’ systems are investigated. Optical characteristics of PVP/PAA/MnO2 nanofluid are measured at wavelength of 220–820 nm. Results indicate that the absorption of H2O/PVP/PAA fluid enhances, while the transmission reduces as the MnO2 ratio increases. The optical microscope images show homogeneous distribution of MnO2 nanoparticles in H2O/PVP/PAA medium. The thermal-energy storage application of H2O/PVP/PAA/MnO2 nanofluid is tested. The results of application indicate that the time of heating decreases with the increase in MnO2 nanoparticles’ concentration. [ABSTRACT FROM AUTHOR]

This paper is dedicated to the research of solar energy issues, namely to increase the efficiency of solar panels and to compare the performance of solar panels in different configurations. The author researches and compares the performance of solar panels with and without trackers. The sun is an inexhaustible source of energy that mankind has yet to appreciate. Solar energy is the kinetic energy of radiation (mainly light) generated by thermonuclear reactions in the bowels of the sun. Solar energy is one such alternative, the neglect of which will in the near future lead to catastrophic consequences for humanity. Solar energy is a progressive method of obtaining various types of energy through solar radiation. Solar energy is one of the most promising and dynamic renewable energy sources (RES). Each year, the increase in commissioned capacity is approximately 40-50%. In the last fifteen years alone, the proportion of solar electricity in the world has exceeded the 5% mark. To increase the efficiency of solar panels, designers and engineers are developing new devices and devices, one of which is a solar tracker. A solar tracker is a device that allows you to control the movement of the sun across the sky, as well as move the solar panel to the position where the absorption of sunlight is most effective. After the conducted experiment, calculations an comparison we can see the next results. Without the solar tracker our panel generated maximum power in 2.4 Watt. After the solar tracking system integration, our panel generated almost 20 (19.8) Watt of power! After this comparison we can tell that the generated power increase in 8.25 Watts. We can also admit that the amount of generated power depends on light intensity. But solar panels are the most effective when the solar beam falls perpendicular to solar cell and solar panel is at an angle of 75 – 85 degrees. [ABSTRACT FROM AUTHOR]

It is shown that one of the known directions of partial elimination of water deficit can be systems for obtaining water from atmospheric air, in which refrigerating machines or units provide a temperature below the dew point temperature. When choosing the types of refrigeration machines or units for these systems, the use of solar energy may be promising, in particular, solar collectors, which are widely used in the world for heating in the cold and transitional periods of the year, as well as for household and sanitary and hygienic needs. Here, absorption ammonia-water systems have great prospects, which, in contrast to lithium bromide analogs, have the ability to work with air-cooled heat dissipating elements. At the same time, the use of ammonia-water absorption refrigeration systems in systems for obtaining water from the atmosphere is difficult due to the insufficient temperature level of the solar energy source. The object of research is a modernized absorption refrigeration unit (ARU), in which additional purification of a weak ammonia-water solution (AWS) is carried out by evaporating part of the ammonia into a vapor-gas mixture. A calculation method has been developed for determining the specific thermal loads on structural elements for given parameters of the working fluid at characteristic points (input-output of elements) with the subsequent determination of the energy efficiency of the refrigerating cycle of the ARU. It has been shown that the composition of the inert gas does not affect cycle efficiency. Replacing hydrogen with helium leads only to a 2-fold increase in the amount of circulating gas, which complicates the operation of the natural circulation circuit between the absorber and the evaporators of ammonia and solution. ARU has the maximum efficiency, operating in the cooling temperature range - from -18 to +12 °С, while the temperature of the end of evaporation has a decisive influence on the energy efficiency. The results of the energy analysis of ARU made it possible to formulate a number of recommendations for developers. It is noted that the initial data necessary for calculating the evaporator of the solution can be obtained as a result of modeling the processes of heat and mass transfer in the approximation of the adiabaticity of the processes. [ABSTRACT FROM AUTHOR]

The study to investigate the thermal performance of solar cooker using a spot Fresnel lens for concentrators of solar thermal energy is conducted. The main objectives of the present work are: a) to develop a new design of the cooking pot of solar cooker as an absorber of solar thermal from a spot Fresnel lens; b) to analyze the relationship of several temperature parameters in the cooking pot with the thermal efficiency of the Fresnel solar cooker (FSC); c) to conduct field test by heating test and cooling test to obtain a performance characteristic of FSC. The experimental test was conducted at Brawijaya University (7.9553°S, 112.6145°E), East Java, Indonesia during August – September 2019. The Fresnel lens operation method uses the azimuth manual tracker to concentrate direct normal irradiance (DNI). The measurement of Direct Normal Irradiance (DNI) was made by the SM 206 Solar Power Meter and placed on the FSC frame. A new design of solar cooking pot has been developed. That is a cylindrical shape for boiling water and food cooking with a cone cavity as a solar collector. While on the cooking pot, the temperature sensor is placed: 1) ambient temperature; 2) cooking pot temperature; 3) focal point temperature on the receiver surface; 4) water temperature in the solar cooking pot. It is connected to the Digi-Sense 12 CH-Scanning Benchtop Thermometer for temperature data acquisition system. The measurement of wind speed was made by Cup Anemometer ABH-4224. The procedure for testing the FSC was developed based on existing international testing standards. The receiver/cooking pot was tested for thermal performance characteristics of cooking by conducting the following tests: 1) no-load test; 2) water heating and cooling tests. The experimental results show that the average stagnation temperature in a cooking pot with a conical cavity receiver was 267.35 °C. The receiver shape with a conical cavity has better heat transfer capability and low heat losses, hence, making it suitable for applications on FSC. DNI ±850 W/m2 produces a focal point temperature of 1064 °C, a heat removal factor of 7.39 W/m2·°C, and an optical efficiency factor of 0.312. Therefore, the thermal efficiency of the FSC is 27.72 %. The thermal efficiency tends to decrease until the end of the process due to the influence of the optical efficiency factor. [ABSTRACT FROM AUTHOR]

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Conceptual designs have been developed for multifunctional solar air dehumidification systems, heat supply (hot water supply and heating), cold supply and air conditioning based on an open absorption cycle with direct regeneration of the absorbent. Such systems are based on pre-drying of the air flow and subsequent evaporative cooling of media in solar refrigeration systems (SRS) and thermal and humid air treatment in solar air conditioning systems (SACS). The authors used the principle of two-stage regeneration of the absorbent. The solar system consists of autonomous dehumidifying and cooling units, with each regeneration stage closed to the corresponding stage of the air absorber stage (air dryer), which allows increasing the concentration of the absorbent from stage to stage (in the range of possible concentrations of the LiBr lithium bromide solution used). Fundamental solutions have been developed for the new generation of gas-liquid solar collectors, which make it possible to exclude the desorber (absorbent solution regenerator) from the concept of the solar system, providing direct regeneration of the absorbent solution.. The work of heat and mass transfer apparatus, which are included in the drying and cooling circuits of absorption systems, is based on the principle of film interaction of gas and liquid flows using a multichannel packed structure of polymeric materials. A preliminary analysis of the capabilities of multifunctional solar absorption systems was carried out on the basis of the experimental data of the authors and the modeling of heat and mass transfer processes in the main elements of the systems with respect to the tasks of solar air conditioning systems (SACS). It is shown that, for practically any sufficiently heavy parameters of external air, solving problems of ensuring its comfortable air parameters can be performed without using traditional refrigeration equipment. The developed SACS solar systems are distinguished by low energy consumption and environmental cleanliness. [ABSTRACT FROM AUTHOR]

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Copyright of Renewable Energy / Vidnovluvana Energetyka is the property of Institute of Renewable Energy of NAS of Ukraine and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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