Thermal Energy Generation Research Articles

DECENTRALIZATION – THE MAIN WAY FOR THE TRANSFORMATION OF THE ENERGY INDUSTRY OF UKRAINE

Topicality. The events of November 2022 showed the absolute instability of Ukraine's centralized energy system. Up to 40% of the centralized energy infrastructure was disabled in two days. Millions of people were left without electricity, heat and water for a long time. Therefore, it is very important to develop the energy sector of the state in the future, taking into account the needs of Ukraine's decentralization policy, in particular, local communitiesAim and tasks. The purpose of the research is to determine the imperatives of decentralization of the energy sector of Ukraine. The main way of developing the energy system of the state is the transition from a centralized to a distributed system. The location of generation systems in united communities makes it possible to switch to systems of cogeneration of electric and thermal energy to increase the efficiency of installed capacities and save fuel significantly by up to 40%.Materials and Methods. The methodological basis for the formation of regional policy should become the best of the world and European practices of the country`s energy sector development. Active use of the methods of system analysis, expert assessment on the implementation of decentralization systems of the energy industry is a guarantee of achieving the priorities of national security of Ukraine in the post-war period. Priority support from the EU and others international donors refers to those projects and programs aimed at decentralization, decarbonization, local economic sustainability and energy independence.Research results. The research substantiates that local communities have great opportunities for using alternative renewable resources for the generation of electricity and thermal energy. First of all, it is biomass, biogas, solar energy, wind energy and geothermal energy. In particular, the authors proved that due to the installation of means of electric energy accumulation, it is possible to raise the level of use of the installed capacities of solar and wind power plants by another 50% and to bring the total level of use of the installed energy capacities to 70%.Conclusions. The active implementation of alternative energy sources into economic practice can become the basis of the national security of the state in the post-war period. It is suggested that Communities use nearby agricultural waste and solid household waste as fuel instead of imported fossil fuel. It is also proposed to create local electric networks combined into virtual power plants within the framework of united communities, including not only all types of generation available on the territory, but also systems of short-term and long-term storage of electric energy. For the long-term storage of large amounts of electrical energy, it is suggested to use accumulators based on cryogenic liquids. It has been proven that due to the installation of means of electric energy accumulation, it is possible to raise the level of use of the installed capacities of solar and wind power plants by another 50% and to bring the total level of use of the installed energy capacities to 70%. Virtual power plants make it possible to significantly increase the amount of generated (consumed) electricity without additional investment costs. Such technologies meet the requirements of the European Union for candidate countries to join the Union and open the possibility of financing projects related to the restoration of the energy system of Ukraine based on renewable sources and advanced energy-efficient technologies.

Experimental validation of rotating detonation for rocket propulsion

Space travel requires high-powered, efficient rocket propulsion systems for controllable launch vehicles and safe planetary entry. Interplanetary travel will rely on energy-dense propellants to produce thrust via combustion as the heat generation process to convert chemical to thermal energy. In propulsion devices, combustion can occur through deflagration or detonation, each having vastly different characteristics. Deflagration is subsonic burning at effectively constant pressure and is the main means of thermal energy generation in modern rockets. Alternatively, detonation is a supersonic combustion-driven shock offering several advantages. Detonations entail compact heat release zones at elevated local pressure and temperature. Specifically, rotating detonation rocket engines (RDREs) use detonation as the primary means of energy conversion, producing more useful available work compared to equivalent deflagration-based devices; detonation-based combustion is poised to radically improve rocket performance compared to today’s constant pressure engines, producing up to 10% increased thrust. This new propulsion cycle will also reduce thruster size and/or weight, lower injection pressures, and are less susceptible to engine-damaging acoustic instabilities. Here we present a collective effort to benchmark performance and standardize operability of rotating detonation rocket engines to develop the RDRE technology readiness level towards a flight demonstration. Key detonation physics unique to RDREs, driving consistency and control of chamber dynamics across the engine operating envelope, are identified and addressed to drive down the variability and stochasticity observed in previous studies. This effort demonstrates an RDRE operating consistently across multiple facilities, validating this technology’s performance as the foundation of RDRE architecture for future aerospace applications.

Experimental and Theoretical Evaluation of a Commercial Luminescent Dye for PVT Systems

Combining photovoltaic (PV) and photo-thermal (PT) energy collection strategies in a single system can enhance solar energy conversion efficiencies, leading to increased economic returns and wider adoption of renewable energy sources. This study focuses on incorporating a commercial luminescent organic dye (BASF Lumogen F Red 305) into ethylene glycol to explore its potential for PVT applications. The optical and electrical characteristics of the working fluid were evaluated at different temperatures under direct solar irradiance. Pristine ethylene glycol reduced the maximum PV cell temperature by 10 °C. The inclusion of luminescent dye at various concentrations further reduced the maximum temperature, with the lowest concentration achieving a 7 °C decrease compared to pristine ethylene glycol. The highest dye concentration (0.50 wt%) resulted in a significant temperature reduction of 12 °C. While electrical conversion efficiencies decreased with increasing dye concentration, all concentrations exhibited higher fill factors compared to the bare PV cell during the 100-min illumination period. A ray-tracing model was employed to analyze the behavior of the luminescent dye and quantify transmitted energy for electricity and thermal energy production. Different concentrations showed varying energy outputs, with lower concentrations favoring electrical energy and higher concentrations favoring thermal energy. Economic assessment revealed the viability of certain concentrations for specific countries, highlighting the trade-off between thermal and electrical energy generation. These findings provide valuable insights for PVT system applications in different geographical and economic contexts.

POWER PLANT FOR PROCESSING
 AGRO-INDUSTRIAL WASTE INTO MOTOR FUEL

In the Russian Federation, the predominant direction in the field of waste management is not recycling, but burial and storage, both authorized and unauthorized. Various types of products, food waste, glass, textiles, polymer production waste are buried in landfills. Plastic bags, various packaging materials, rubber products decompose for tens and hundreds of years, polluting the environment. (Research purpose) The research purpose is developing an energy plant for the production of motor fuel and fertilizers by processing agro-industrial waste based on pyrolysis. (Materials and methods) Applied methods of numerical analysis, in theoretical studies used the basic provisions and laws of heat balance and mathematics. The experimental data obtained were processed by methods of mathematical statistics using electronic computers. (Results and discussion) We have developed a technology for recycling used rubber products with associated generation of thermal and electrical energy. The characteristics of the power plant operation during the processing of rubber products, as well as the composition of pyrolysis gas were determined: CO – 25, CO2 – 18, CH – 17 percent, pyrolysis temperature – 700-800 degrees Celsius. Taking into account the characteristics of rubber products, an experimental sample of a power plant was assembled as fuel. It was determined that the average payback period of this power plant is approximately 1.5-2 years. (Conclusions) This technology makes it possible to solve the problem of recycling car tire waste both from an environmental point of view and from an economic feasibility. During recycling, additional thermal and electrical energy is generated, which is directed to the needs of the production of its own economy.

Experimental study on thermoelectric effect pattern analysis and novel thermoelectric coupling model of BIPV facade system

Electrical and thermal energy are the primary forms of useful energy generated by building integrated photovoltaic façade (BIPV façade) systems, while their interaction during operation remains unclear. This study aims to analyze the energy generation patterns and quantify the impact of thermoelectric coupling in BIPV façade systems. Through long-term outdoor experiment conducted on an actual BIPV façade system, the underlying regularity of thermoelectric coupling was discovered by analyzing the electrical and thermal characteristics. Results showed that under same solar radiation, enlarged air channel spacing led to a 53.22% increase in air channel heat and a 12.27% increase in mean thermal efficiency. Additionally, the heat proportion increased by approximately 15%, while the electricity proportion decreased by 15%. Furthermore, the mathematical relationships of the thermoelectric association factors were determined to quantify the observed thermoelectric generation patterns. A novel thermoelectric coupling model was established and validated with errors below 6.21% for accurate estimation of thermoelectric performance under actual operating conditions. Results emphasized both thermal and electrical energy generation of BIPV façade, which offers a new perspective on the comprehensive utilization of thermoelectric association in BIPV façade design and building applications, opening avenues for enhanced energy efficiency in renewable energy systems.

Creating Quantitative Regulation Principles of the Heating Networks’ Parameters Based on the Life Cycle Analysis

Materials and Methods. The elaboration of the heating networks should be carried out in compliance with the currently enacted Code of Practices “Information modeling in construction. Rules for the objects’ information model creation at different stages of the life cycle». The life cycle can be divided into four stages. It is noted that each type of digital information model at each stage of the life cycle correlates with the certain level of elaboration, which envisages the minimum of geometric, spatial, quantitative and attributive data necessary to solve the task of information modeling at a specific stage of the object's life cycle.Results. 4th generation heating supply technologies allow reducing the temperature of the heat-carrying agent, hereby creating conditions for commencing the heating networks’ transit to the low temperature type of systems. As a result, reducing the heat carrying agent’s temperature, allows using more flexible polymer materials for the pipelines. In addition, application of the comprehensive approach to the heating networks innovative development is the important prerequisite for further development of the district heating infrastructure and technologies.Discussion and Conclusions. The main focus for improving the heating sector development should lie in the elaboration and implementation of the new technologies and digital information models, which will improve the quality of thermal energy generation, transportation and distribution.

Optimization of flexible thin-film photovoltaic converters based on CdS/CdTe heterosystem for integration with solar thermal collectors

The paper introduces the concept of a photoenergy system based on film photovoltaic converters using the CdS/CdTe heterosystem. The goal is to develop a design solution for a flexible thin-film photovoltaic converter system that can be directly mounted on a heat collector plate, integrating photovoltaic converters with thermal collector systems. The paper highlights the limitations of traditional silicon-based photovoltaic converters and propose using flexible photovoltaic converters based on CdS/CdTe, which have concentrated absorption within the visible range and allow unobstructed flow of long-wave solar radiation for efficient thermal energy generation. The paper discusses the methods of obtaining samples of flexible photovoltaic converter ITO/CdS/CdTe/Cu/Au solar cells, including the deposition of layers on polyimide films, chloride treatment, and annealing processes. Analysed the impact of the “chloride” treatment on the structural and optical characteristics of the base layers and present the overall appearance of the thin-film photovoltaic converter samples. The structural analysis of the cadmium telluride films is conducted using X-ray diffractometry techniques, while the optical properties are investigated using a spectrophotometer. The light-voltage characteristics of the photovoltaic converter samples are measured under illumination conditions, and various output parameters and characteristics of the photovoltaic converter are determined. The authors emphasize the significance of optimizing the performance of the cadmium telluride layer in the flexible photovoltaic converter structure and discuss the variation of technological parameters to enhance efficiency. Paper presents the output parameters and light diode characteristics corresponding to different thickness ranges of the CdS layer. Overall, this paper provides valuable insights into the development of flexible film photovoltaic converters based on the CdS/CdTe heterosystem for integrated photovoltaic and thermal collector systems. The experimental methods and results contribute to the understanding of optimizing the performance of the photovoltaic converters and offer potential applications for autonomous heat supply systems.

Economic operation of networked flexi-renewable energy hubs with thermal and hydrogen storage systems based on the market clearing price model

This paper presents the energy management of flexi-renewable energy hubs in electric and thermal networks based on the market clearing price model and participation of hubs in the energy market. Renewable sources include wind sources and bio-waste units, where the latter simultaneously plays a role in electrical and thermal energy generation. Hydrogen and thermal storage are used as a source of flexibility in the hub. The proposed scheme has a two-level formulation. Its upper level considers the participation of hubs in the energy market. It maximizes the expected profit of energy hubs by observing the operational constraints of power sources and storage devices (in the form of a hub) and the hub's flexibility limitation. The lower-level problem presents the market clearing price model. In this problem, the expected operation cost of the generation units in the electric and thermal networks is minimized subject to satisfying the constraints of the optimal power flow of the mentioned networks. The Karush-Kuhn-Tucker method provides a single-level formulation of the scheme. Also, stochastic optimization is adopted to model the uncertainties of load and renewable power to examine the flexibility of energy hubs accurately. Finally, by evaluating the numerical results obtained from different study cases, the scheme can improve the operating conditions of energy networks and obtain optimal flexibility and economic conditions for energy hubs. The hydrogen storage device next to the thermal storage device can achieve 100% flexibility conditions for the hubs. Storage devices can enhance the economic status of renewable hubs by about 9.2%. The energy management of flexi-renewable hubs improves energy networks' operational and economic status by 21–24% and 8.8% compared to power flow studies.

Performance investigation of truncated low concentrating photovoltaic-thermal systems with V-trough, compound hyperbolic and compound parabolic concentrators

The electric conversion efficiency of a conventional photovoltaic cell in the market is around 13–22%. The remaining part is converted into heat. It increases the temperature of the photovoltaic cell and decreases the electrical efficiency. In concentrating photovoltaic systems, it comes into prominence. In this study, a comparative performance analysis was carried out among non-imaging concentrating photovoltaic thermal systems with various truncation levels of the reflector to attain uniform illumination and better electrical and thermal energy conversion performance. Compound Parabolic, V-trough, and Compound Hyperbolic concentrators were evaluated in terms of optical performance to decide distinctive truncation levels. The reflector sizes of 72%, 55%, and 42% were considered for evaluating the concentrating photovoltaic-thermal systems. The results show that the truncation reduces the photovoltaic cell temperature and provides more uniform temperature distribution. In the case of Compound Parabolic Concentrator- photovoltaic thermal, the average thermal and electrical power generation decreases by only 0.5% and 1.3% for 28% truncation. Compound parabolic hyperbolic- photovoltaic thermal provided about 45.5% and 21.7% higher average thermal energy generation per unit reflector area compared to V-trough and CPC, respectively. CHC provided about 59.8% and 32.8% higher average electrical power generation per unit reflector area compared to V-trough and CPC, respectively. Truncation reduces the thermal and electrical power generation while the power generation per unit reflector area increases. It indicates that the truncation provides effective use of the reflector. Compound Hyperbolic Photovoltaic Thermal system has the highest power generation per unit reflector area for all truncation levels and incidence angles.

Tritium Opportunities and Challenges for Fusion Developments Worldwide—CNL and UKAEA View

The commercial generation of electricity and high-temperature thermal energy via fusion technology remains one of the promising alternatives to help meet the challenging targets to decarbonize the global energy system. Fusion technology can play a significant role as part of the long-term switch away from carbon-based fuels for electricity and heat due to high energy output, usage of abundant fuel that can be made available without environmental degradation, and avoidance of long-lived and toxic transuranics. Many countries have their own fusion research and development programs, while large research efforts are being undertaken in multicountry collaborations, such as ITER. Recently, fairly new (semi-) commercial organizations have been successful in initiating independent development programs funded by government grants and private investments. Different fusion reactor technologies still share many challenges, with one of the major issues being the management of the deuterium-tritium (DT) fuel cycle and associated auxiliary systems. These different fusion technology developers could benefit immensely from existing and available DT expertise, allowing them to focus primarily on the physics and mechanical aspects of their reactor technologies while finding support for common tritium technological challenges through collaboration. As world-leading experts in DT technology, Canadian Nuclear Laboratories (CNL) and the United Kingdom Atomic Energy Agency(UKAEA), are well positioned to support such needs of the fusion industry. This paper broadly explores the worldwide DT challenges, identifies opportunities where tritium expertise is key to the development of fusion infrastructure, and presents a view of how CNL and UKAEA are addressing these opportunities for the various fusion developers. This paper presents a holistic view that may be informative to future tritium roadmap and decision-making exercises conducted within the community.

The biomethane generation potential of wastes and wastewaters from the sericulture, fisheries, and agro-industrial sectors in India

The global problem of climate change and difficulties related to energy access, air pollution, and water pollution in India (and other developing countries) necessitate the need to look for alternative clean, local, and low-carbon energy sources for displacing fossil fuels. This paper analyses the existing waste-to-biomethane potential of the sericulture, fisheries, and agro-industrial sectors in India, which have mostly been neglected previously in India's waste-to-energy assessments. In the process, the volume of wastewaters generated from India's agro-industries are also estimated, data on which are scarce in the academic and grey literature. India's annual biomethane potentials (for 2018–19) were found to be 88 million m3, 207 million m3, and 3514 million m3 from the three sectors, respectively. To assess the energy generation potential of these wastes, a comprehensive literature review was conducted and data on residue-to-product ratios, results of proximate analyses, and specific biomethane yields were either compiled or calculated. The gross thermal energy and electricity generation potentials are 132 PJ and 22 TWh respectively; between 19 and 95 million people can benefit from such waste-to-energy production, depending on the end use of the biomethane for electricity generation or as a domestic cooking fuel. The corresponding mean removal of organic pollution from India's surface waters can be between 5.5 and 9.3 million tonnes of chemical oxygen demand. For the end uses of biomethane in electricity generation and cooking, the cumulative GHG abatements attributable to these industries are 11.4 million tonnes and 6.8 million tonnes of carbon dioxide-equivalent respectively. Besides the numeric results reported, this paper also contains a comprehensive compilation of data on waste characteristics and biomethane productions. The present status of biogas generation and related policy implementation in India are reviewed and discussed. Overall, our findings indicate that biomethane from these wastes and wastewaters can generate substantial energy for India, is in line with recent government policies, and can aid India in achieving six Sustainable Development Goals of the United Nations.

Sustainable Approaches to Incorporate Plant-Based Biomaterials in Power Generation

Biomass-derived materials have traditionally been used to generate electrical energy through the combustion of their organic components. However, within the past few years, certain common biomass compounds, especially plant-based products such as cellulose and lignin, have drawn attention in the energy field due to their wide availability, low cost, and chemical versatility. In the case of cellulose, the combination of crystalline and amorphous domains, along with the high surface area and abundance of hydroxyl groups, has allowed for its application in multiple devices to harvest energy from the environment. However, to date, there are no reviews focusing on the different approaches that have been developed to implement these sustainable materials in the generation of renewable energies and the desirable material properties for these applications. This manuscript reviews alternative ways that have been developed to exploit biomass compounds in power generation, especially cellulose and lignin. Three different types of energy harvesting are discussed: mechanical, osmotic, and thermal energy. In the case of mechanical energy, the application of plant-derived materials in piezoelectric and triboelectric generators is described. In both cases, approaches where the biomass material has an active role in power generation instead of acting as a mechanical support are reported. For osmotic energy, the performance of inverse electrodialysis systems and the use of plant-derived materials, including the chemical modifications carried out to allow for their use for energy generation, was reviewed. Finally, for thermal energy generation, the reported work on biopolymer-based devices that work using thermoelectricity has been summarised. In each case, the latest advances in the field from the materials science perspective and the reported performance were described. Hybrid approaches involving the combination of biomass materials with other components have also been considered and compared with the performance obtained using biopolymers alone. Current limitations and opportunities are, finally, discussed to offer an overview of the current landscape and indicate future directions of the field.

3E (energy, economic, environmental) multi-objective optimization of CCHP industrial plant: Investigation of the optimal technology and the optimal operating strategy

The article describes the application of an innovative multi-objective optimization model for tri-generative energy systems, based on three objective functions: technical, economic, and environmental. The proposed algorithm was used to simulate the daily operation of several tri-generative system configurations, counting for a total of 31,680 simulations. Thereafter, a critical examination of the data was carried out and then comparisons were made between the 22 studied technology sets, by considering internal combustion engines, solid oxide fuel cells, proton exchange membrane fuel cells, absorption heat pumps, and compression gas heat pumps, lithium-ion, and lead-acid batteries. For the analyzed case study, relating to a large industrial user, the average electrical load in the four reference periods is equal to 4970 kW. The optimal tri-generation plant for this type of user turned out to be composed of: SOFC fueled by methane with a size of 5 MWe, a lithium-ion storage system with a maximum size of 500 kW, an absorption heat pump with a size of 390 kW, gas compression heat pump for the generation of cooling energy with size equal to 390 kW, and gas compression heat pump for the generation of thermal energy with size equal to 1600 kW.

Assessment of thermodynamic performance of a novelty solar-ORC configuration based hydrogen production: An experimental study

In this study, a solar-Organic Rankine Cycle (ORC) assisted hydrogen production system was experimentally investigated. An evacuated tube heat pipe solar collector (ETHPSC) was used for thermal energy generation. The tubes used in this study were produced differently from the tubes of the conventional heat pipe. The condenser area of the vacuum tubes used was made of glass instead of copper. Moreover, acetone was used as the fluid in the tube. The thermal energy obtained from the collector was used as a heat source for electrical energy in the ORC system. A uniquely designed ORC system is modeled and manufactured. The electrical energy obtained from the ORC unit was used for hydrogen production by means of the proton exchange membrane electrolyzer (PEMe). As a result of the study, two different efficiency analyses were made. If all of the electricity produced in the S-1 scenario was spend on hydrogen production, the energy and exergy efficiency were calculated as 3.45% and 2.15%, respectively. In the S-2 scenario, if some of the electricity produced was spend on hydrogen production, the energy and exergy efficiency of the whole system were found to be 0.01446% and 0.002146% respectively. In addition, 0.000004433 kg/s hydrogen production was obtained from the presented system.

Experimental Study on the Efficiency of Dynamic Marine Thermal Energy Generator Based on Phase Change Compensation

Miniaturized detection devices in the ocean generally experience problems such as short endurance and unreliable power supplies. This article aimed to develop a dynamic ocean temperature difference energy collection device to capture ocean temperature difference energy and provide objective electricity for stable detection devices. The main focus was to conduct experimental research on the effectiveness of a dynamic ocean temperature difference energy power generation device. During the research process, the fact that ammonia gas in a working fluid is easy to liquefy and vaporize was utilized. By utilizing the increase in seawater temperature during the floating process of the device, it vaporized and drove the turbine to rotate for power generation. In the structural design, multiple sets of small air chambers were creatively proposed, which could effectively control the air pressure and improve the stability of the airflow. By charging the airflow to impact the turbine, multiple sets of power generation fans were used to form a stable current. Further, the buoyancy of the device could be changed by adding phase change materials between the air chamber and the device shell, and the temperature difference between the two ends of the phase change materials could be used to change the electron density of the material to form a weak current. In this experimental study, concepts such as the structural design of multiple small gas chambers, miniaturization of energy collection devices, compensation power generation of phase change materials, and application scenarios of devices combined with Argo buoys were all proposed for the first time. The results of this experimental study indicate that the overall power generation of the device is about 2A, and its maximum output power amplitude is about 22 W. The cyclic thermal efficiency of the power generation device can be increased from +0.19% to +0.88%. The development of this thermoelectric power generation device can provide a considerable stable power supply for ocean observation devices, especially the buoy device represented by Argo, which can extend the endurance of deep-sea exploration devices.

A preliminary evaluation of different residual biomass potential for energy conversion in a micro-scale downdraft gasifier

Residual biomass can be a promising alternative to replace fossil fuels for energy production. Through small-scale gasification systems it is possible to obtain a fuel gas from solid biomass that can be used for electrical and thermal energy generation. In this work, six different biomasses (five agro-industrial residues and A1 ENplus pellets) were tested in a lab-scale prototype. For each tested feedstock, elemental and ash analyses were carried out. The contaminant amount in the produced gas was measured as well as the mass and energy fluxes to calculate the gasification efficiency. The ratio between the pressure drop across the reactor and the gas flow raised to the square was introduced to compare the gasifier behavior at different power outputs. The results showed that with the exclusion of the tests run with cork, the other tested agro-industrial residues (pistachio shell, hemp and driftwood) performed acceptably in terms of efficiency, providing also a char with a carbon content over 70% as by-product.

Solar radiative and chemical reactive influences on electromagnetic Maxwell nanofluid flow in Buongiorno model

BackgroundThe generation, utilization, adaptation, and transmission of thermal energy are all included in the controller topic of heat transport. Engineering and manufacturing disciplines include nutrition processing, the construction of food herbs, electric refrigeration, microturbines, and other fields rely heavily on heat transport. Because of the fascinating possibility in productions including the fabrication of polymers, papers, crystal glasses, and other materials, academics tried to probe the impact of heat transfer on liquid via an expandable sheet. ObjectiveTo conduct our inquiry, we built a symmetric system connecting the properties of bio convection into an extended Maxwell nanofluid (MNF) using Fourier and Fick equations in a symmetrical stretchable slippage. Consideration has been given to the Cattaneo-Christov fluxing model. According to a Cattaneo-Christov connection (CCC), the Buongiorno occurring is likewise used for a symmetrical movement of nanofluids (NFs) in the Maxwell liquid. FormulationThe regulator scheme that governs PDE was converted into ODE for the numerical solution utilizing similarity conversions. Galerkin finite element technique (GFEM) is created using the COMSOL application to produce mathematical conclusions for non-linear equations. FindingIn contrast to the updated Fourier-Fick scenarios, we saw higher temperatures and concentrations for Fourier-settings to calculate the current Biot quantity and general MNF factor, the heat outline is elevated. NoveltyThere is currently no information in the available literature on GFEM research of Maxwell nanofluid (MNF) in the occurrence of temperature producing, radiation temperature fluxing, and Cattaneo-Christov mass and temperature fluxing.

Experimental Study on the Mechanical Behavior of Dry Corn Stalk Cutting.

This work presents an experimental study of cutting corn stalks for thermal energy generation. The study was carried out for the values of blade angle in the range of α = 30-80°, distance between the blade and the counter-blade g = 0.1, 0.2, 0.3 mm and the velocity of the blade V = 1, 4, 8 mm/s. The measured results were used to determine shear stresses and cutting energy. The ANOVA variance analysis tool was used to determine the interactions between the initial process variables and the responses. Furthermore, the blade load-state analysis was carried out, together with determining the knife blade strength characteristic, based on the determination criteria for the strength of the cutting tool. Therefore, the force ratio Fcc/Tx was determined as the determinant of strength, and its variance characteristic in the function of the blade angle, α, was used in the performed optimization. The optimization criteria entailed the determination of such values of the blade angle, α, for which the cutting force value, Fcc, and the coefficient of knife blade strength approached the minimum value. Hence, the optimized value of the blade angle, α, within the range 40-60° was determined, depending on the assumed weight parameters for the above-mentioned criteria.

3D Solar Harvesting and Energy Generation via Multilayers of Transparent Porphyrin and Iron Oxide Thin Films

Photovoltaic solar cells have been extensively used for various applications and are considered one of the most efficient green energy sources. However, their 2D surface area solar harvesting has limitations, and there is an increasing need to explore the possibility of multiple layer solar harvest for enhanced energy density. To address this, we have developed spectral-selective transparent thin films based on porphyrin and iron oxide compounds that allow solar light to penetrate multiple layers, significantly increasing solar harvesting surface area and energy density. These thin films are designed as photovoltaic (PV) and photothermal (PT) panels that can convert photons into either electricity or thermal energy for various green energy applications, such as smart building skins and solar desalination. The advantages of this 3D solar harvesting system include enlarged solar light collecting surface area and increased energy density. The multilayer system transforms the current 2D to 3D solar harvesting, enabling efficient energy generation. This review discusses recent developments in the synthesis and characterization of PV and PT transparent thin films for solar harvesting and energy generation using multilayers. Major applications of the 3D solar harvesting system are reviewed, including thermal energy generation, multilayered DSSC PV system, and solar desalination. Some preliminary data on transparent multilayer DSSC PVs are presented.

The Economic and Environmental Evaluations of Combined Heat and Power Systems in Buildings with Different Contexts: A Systematic Review

Cogeneration systems—also known as combined heat and power systems—form a promising technology for the simultaneous generation of power and thermal energy while consuming a single source of fuel at a site. A number of prior studies have examined the cogeneration systems used in residential, commercial, and industrial buildings. However, a systematic review of the economic and environmental evaluations of the system is not found in the literature. The present study aims to address this research gap by reviewing the most relevant studies on the cogeneration systems applied to buildings in different contexts (e.g., residential, commercial, and industrial) and provides systematic evaluation approaches from economic and environmental perspectives. Results show that the cogeneration system can significantly reduce energy consumption, operating costs, carbon dioxide equivalent emissions, and positive performance on other relevant parameters. The present study provides extensive evidence to show that the cogeneration system is simultaneously economically profitable and environmentally friendly in various application contexts. To achieve the maximum benefits from cogeneration systems, several practical suggestions are provided for their successful installation and implementation in real-life situations.