Energy-intensive Research Articles

Maximizing thermal management of photovoltaic-thermal systems with proper configuration of porous fins and phase change materials

Effective thermal management is crucial to enhance the performance and longevity of photovoltaic-thermal (PVT) systems. Phase change materials (PCMs) offer a promising solution for absorbing excess heat from PV modules; however, their poor thermal conductivity limits their effectiveness. This work explores the incorporation of porous fins within PCMs to improve heat absorption and thermal regulation in PVT systems. A detailed mathematical model is developed to analyze the effects of varying fin porosity (0.85 to 0.95), fin thickness (7 to 21 mm), fin height (7 to 21 mm), and fin inclination (-15° to 30°) on PCM melting and PVT cooling performance. Results show that optimally configured porous fins significantly enhance PCM melting rates and heat extraction from PV cells. Incorporating optimal fins reduces peak PV temperatures by up to 5°C compared to PCM alone at irradiation rate of 1000 W/m2. Meanwhile, reducing the fin thickness from 21 to 7 mm accelerates the overall PCM melting rate by 14%. The cooling performance also shows a nonlinear increase with fin tilt angle, with maximum enhancement occurring at 15° downward tilt for the studied configuration. The optimized fin-enhanced PVT design achieves 3.1% higher electrical efficiency and 15% increase in thermal efficiency compared to conventional PCM-PVT systems without fins. Findings provide design guidance to harness porous fins for maximized PCM-based cooling of PVT systems.

Experiment and dynamic simulation of micro gas turbine combined with concentrated solar power system

The solar micro gas turbine (SMGT) system is a promising solution to address the instability and intermittency of renewable energy sources. Its dynamic characteristics under unstable input conditions and uncertain output load demands are crucial for peak shaving. This paper constructs an SMGT system based on experiments with micro gas turbine (MGT) and concentrated solar power (CSP), analyzing the impact of integrating CSP system on the MGT. Then the performance of the SMGT under varying ambient conditions and load demands is studied. Results show that in grid-connected mode, the turbine speed of MGT and SMGT is determined by ambient temperature and set power, with electrical efficiency decreasing as temperature and DNI increase. The solar receiver in the SMGT should maximize temperature increase while maintaining pressure loss below 55 kPa. Additionally, a higher heat capacity can reduce sensitivity to ambient changes but also extends stabilization time. Under real solar radiation, the SMGT system can keep constant power within 0.6% fluctuation, with a solar share of 36.5%. When combined with photovoltaic, the hybrid system’s maximum power fluctuation does not exceed 2.6%, with a solar share of 48.8%. This study provides guidance for optimizing SMGT systems and their application in peak shaving scenarios.

Simulation of thermoelectric-photovoltaic system integrated with various shapes of cooling ducts filled with nanomaterial

Incorporating thermoelectric (TE) modules into photovoltaic/thermal (PVT) systems can markedly increase energy output by improving the overall efficiency of energy conversion. This research focused on the design and simulation of a PVT system integrated with a TE module, utilizing ANSYS Fluent. The study assessed four different tube cross-sectional shapes—circular, square, elliptical, and triangular—all with the same cross-sectional areas. Moreover, the investigation included the impact of Cu-alumina/H2O hybrid nanofluid at a 0.024 % volume concentration, fluid inlet velocity (ui), and solar radiation (G) on PV temperature (TPV) and the overall productivity. The outputs showed that the triangular configuration considerably reduced TPV compared to the other shapes. This configuration also generated the highest thermal power, reaching 130.84 W. Additionally, at ui = 0.19 m/s, the unit's thermal efficiency and overall electrical efficiency increased by 0.93 % and 0.22 %, respectively.

Heat Energy Utilization of a Double-Flash Geothermal Source Efficiently for Heating/Electricity Supply through Particle Swarm Optimization Method

The principal aim of this article is to optimize the thermal and electrical efficiency of a geothermal combined heat and power system through metaheuristic particle swarm optimization (PSO) method. The objective of this research is to conduct a thorough analysis of the incorporation of metaheuristic PSO technique, with a specific emphasis on the potential advantages and obstacles associated with the utilization of metaheuristic approaches in improving the effectiveness of geothermal energy systems. The utilization of a double-flash geothermal system in conjunction with a transcritical carbon dioxide Rankine cycle is utilized for the co-generation of electricity and thermal energy. The research utilized a PSO method to enhance power generation, heating capacity, and overall system efficiency. The PSO algorithm was employed to determine the optimum operational parameters for a pressure level of 820 kPa and a pressure ratio of 1.59, leading to the maximization of power output to 2591.4 kW The PSO algorithm effectively identified the optimal operational parameters as a pressure of 820 kPa and a pressure ratio of 1.59, resulting in the achievement of a peak power output of 2591.4 kW. The methodology has determined that a pressure of 916.4 kPa and a pressure ratio of 1.5 represent the optimal parameters for achieving a maximum heating capacity of 12329.1 kW.

Scalable ammonia synthesis on the modified crystal structure of Cu3PS4 electrocatalyst

Ammonia production, which is vital for agricultural and industrial applications, typically relies on energy-intensive processes that contribute to global CO2 emissions. Electrochemical nitrogen reduction is a promising alternative, although it faces challenges such as low yield and selectivity. Transition-metal-based catalysts, particularly Cu, are promising for overcoming these limitations. Cu3PS4 catalysts were synthesized and evaluated using a 9 cm2-scale electrode, revealing enhanced performance attributed to change in the crystal and electronic structure of Cu, facilitating N2 adsorption and improving the reaction activity. Notably, the ammonia synthesis rate reached 128 μg h-1 mgcat-1 at −1.0 V vs. RHE and faradaic efficiency was 34 % at −0.8 V vs. RHE. These findings provide potential insights into the improvement of practical electrochemical synthesis of ammonia.

Propane wet reforming over PtSn nanoparticles on γ-Al2O3 for acetone synthesis

Acetone serves as an important solvent and building block for the chemical industry, but the current industrial synthesis of acetone is generally accompanied by the energy-intensive and costly cumene process used for phenol production. Here we propose a sustainable route for acetone synthesis via propane wet reforming at a moderate temperature of 350 oC with the use of platinum-tin nanoparticles supported on γ-aluminium oxide (PtSn/γ-Al2O3) as catalyst. We achieve an acetone productivity of 858.4 μmol/g with a selectivity of 57.8% among all carbon-based products and 99.3% among all liquid products. Detailed spectroscopic and controlled experiments reveal that the acetone is formed through a tandem catalytic process involving propene and isopropanol as intermediates. We also demonstrate facile ketone synthesis via wet reforming with the use of different alkanes (e.g., n-butane, n-pentane, n-hexane, n-heptane, and n-octane) as substrates, proving the wide applicability of this strategy.

Design of a Novel Hybrid Concentrated Photovoltaic–Thermal System Equipped with Energy Storages, Optimized for Use in Residential Contexts

Concentrated photovoltaic (CPV) technology is based on the principle of concentrating direct sunlight onto small but very efficient photovoltaic (PV) cells. This approach allows the realization of PV modules with conversion efficiencies exceeding 30%, which is significantly higher than that of the flat panels. However, to achieve optimal performance, these modules must always be perpendicular to solar radiation; hence, they are mounted on high-precision solar trackers. This requirement has led to the predominant use of CPV technology in the construction of solar power plants in open and large fields for utility scale applications. In this paper, the authors present a novel approach allowing the use of this technology for residential installations, mounting the system both on flat and sloped roofs. Therefore, the main components of cell and primary lens have been chosen to contain the dimensions and, in particular, the thickness of the module. This paper describes the main design steps: thermal analysis allowed the housing construction material to be defined to contain cell working temperature, while with deep optical studies, experimentally validated main geometrical and functional characteristics of the CPV have been identified. The design of a whole CPV system includes thermal storage for domestic hot water and a 1 kWh electrical battery. The main design results indicate an estimated electrical conversion efficiency of 30%, based on a cell efficiency of approximately 42% under operational conditions and a measured optical efficiency of 74%. The CPV system has a nominal electric output of 550 Wp and can simultaneously generate 630 W of thermal power, resulting in an overall system efficiency of 65.5%. The system also boasts high optical acceptance angles (±0.6°) and broad assembly tolerances (±1 mm). Cost analysis reveals higher unit costs compared to conventional PV and CPV systems, but these become competitive when considering the benefit of excess thermal energy recovery and use by the end user.

Effects of regulating the cathode gas properties on the ammonia-fueled solid oxide fuel cell. Part I. Parasitic power consumption and electrical efficiency after increasing O2 and H2O

This study designed and simulated a kW-scale SOFC system equipped with liquified O2 and NH3 tanks for unmanned underwater vehicles (UUVs). Optimizing the parasitic power consumption and electrical efficiency was performed via using oxygen-enriched cathode gas, in-cell cracking of ammonia and adding steam into cathode gas coupled with phase change of recycle steam. The results show increasing O2 concentration helps improve the net system electrical efficiency from 47.9% at simulate air to 51.7% at pure O2. The use of in-cell cracking increases the net system electrical efficiency by 1.3% on this basis. Interestingly, substitution of O2 to H2O would slightly reduce the net electrical efficiency of the system with O2-enriched cathode gas (e.g., decreased by 0.2% when using 40% H2O); however, substitution of N2 to H2O would help improve the net electrical efficiency of the system with simulated air as cathode gas (e.g., increased by 1.2% when using 40% H2O).

Influence of blasting charge distribution on the energy required for communition of rock

The most energy-intensive process in the mining industry is particle size reduction - comminution. The first phase of this process is blasting to fragment the rock from the initial Boussinesq's half-space size. Scientific literature demonstrates that the output of a blast in terms of fragment size distribution can be manipulated by varying the specific charge (powder factor) and charge distribution. This study focuses on the influence of blasting on the internal resistance of the blasted fragments; in particular the influence of the spatial distribution of charges. Small-scale blasts were performed on 14 marble blocks using different powder factors and charge distributions. Three control blocks were fragmented by mechanical means for comparison. The results show the correlations between charge distributions and the specific energy of mechanical comminution. Opportunities for adjusting charge diameter and distribution in opencast blasts to improve the performancet of comminution circuits are discussed.

Potential for Electrical Energy Savings in AC Systems by Utilizing Exhaust Heat from Outdoor Unit

This study explores the potential of utilizing waste heat from air conditioning systems, one of the largest consumers of electrical energy. Currently, most of the waste heat generated by outdoor units is typically released into the environment without being utilized, leading to missed energy-saving opportunities. This study analyzes the potential for improving electrical energy efficiency in air conditioning (AC) systems by harnessing this waste heat. Two primary approaches are evaluated: the first is the use of waste heat for domestic water heating, and the second is the conversion of heat into electrical energy using thermoelectric generators (TEG). The results of this research indicate that both methods have the potential to improve overall energy efficiency significantly. However, challenges related to conversion efficiency and integration of these technologies with AC systems require further, more specific studies. These findings are expected to contribute to more efficient and environmentally friendly cooling systems by optimizing technology and overcoming barriers to wider implementation.

Cross-Coupling of Gaseous Alkanes with (Hetero)Aryl Bromides via Dual Nickel/Photoredox Catalysis.

Gaseous alkanes represent the most abundant carbon-based chemical feedstocks in our planet. However, the intrinsic inertness of their C-H bonds has rendered the use of these alkanes very difficult for purposes beyond aerobic combustion and energy intensive processes. Thus, clean and energy-efficient transformations for their use in synthetic organic chemistry are still rare. Here we report a catalytic methodology for the direct cross-coupling of gaseous alkanes with (hetero)aryl bromides through the combination of metallaphotoredox-mediated hydrogen atom transfer and nickel catalysis. This protocol provides an efficient platform for the addition of short alkyl groups into diverse (hetero) aromatic rings, providing a wide range of high-value alkyl(hetero)arenes, and bypassing the longstanding need of using preactivated alkylating agents in C(sp2)-C(sp3) cross-couplings. The method features high chemoselectivity, regioselectivity and a remarkable functional group tolerance, operates under mild conditions, and exhibits operational simplicity.

Cross‐Coupling of Gaseous Alkanes with (Hetero)Aryl Bromides via Dual Nickel/Photoredox Catalysis

Gaseous alkanes represent the most abundant carbon‐based chemical feedstocks in our planet. However, the intrinsic inertness of their C‐H bonds has rendered the use of these alkanes very difficult for purposes beyond aerobic combustion and energy intensive processes. Thus, clean and energy‐efficient transformations for their use in synthetic organic chemistry are still rare. Here we report a catalytic methodology for the direct cross‐coupling of gaseous alkanes with (hetero)aryl bromides through the combination of metallaphotoredox‐mediated hydrogen atom transfer and nickel catalysis. This protocol provides an efficient platform for the addition of short alkyl groups into diverse (hetero) aromatic rings, providing a wide range of high‐value alkyl(hetero)arenes, and bypassing the longstanding need of using preactivated alkylating agents in C(sp2)‐C(sp3) cross‐couplings. The method features high chemoselectivity, regioselectivity and a remarkable functional group tolerance, operates under mild conditions, and exhibits operational simplicity

Thermodynamic performance analysis of a new air energy storage multigeneration system

This paper proposes a chemical looping hydrogen generation-solid oxide fuel cell combined cooling, heating, and power system that utilizes compressed air energy storage and liquefied natural gas, aiming to address the issues of instability in renewable energy power generation and waste of liquefied natural gas cold energy. The scheme achieves CO2 capture and efficient power generation while also addressing grid fluctuations and the utilization of waste cold energy. The compressed air energy storage system is employed to supply air centrally, eliminating the power consumption of traditional air compressors while improving discharging efficiency. Aspen Plus software and embedded Fortran are used for system simulation. The system is comprehensively evaluated through energy analysis, exergy analysis, and sensitivity analysis. The results indicate that the discharging efficiency, energy round-trip efficiency, and round-trip electrical efficiency are 87.56%, 81.57%, and 67.82%, respectively. The purity of CO2 capture is 99.72%. Sensitivity analysis indicates that the outlet pressure of the air storage tank and fuel flow are the main influencing parameters for system performance. Increasing the fuel flow can effectively enhance system power output, but efficiency will decrease. The outlet pressure primarily influences the power output of the gas turbine and discharging time. Overall, this system provides theoretical guidance and new ideas for efficient energy utilization.

The Application of Pinch Technology to a Novel Closed-Loop Spray Drying System with a Condenser and Reheater.

Spray drying is an energy-intensive process in industrial use, making energy recovery a critical focus for improving overall efficiency. This study investigates the potential of integrating heat-recovery systems, including an innovative air reheater, into a closed-loop spray-drying unit to maximise energy savings. Through detailed pinch analysis, the system achieved a very low approach temperature, averaging 3.48 K, which is significantly lower than that of conventional open-loop systems. The study quantifies the energy-recovery potential by demonstrating that the integration of heat-recovery components can reduce the external heating demand by up to 30%. This not only enhances heat-transfer efficiency but also lowers operational costs and reduces the system's environmental impact. The results suggest that closed-loop systems with air reheaters offer a scalable solution for improving energy efficiency across different industrial applications. The research highlights a new paradigm: focusing on latent energy within the system rather than adjusting individual operational variables.

Analysis and performance prediction of a building integrated photovoltaic thermal system with and without phase change material

Increasing energy demand in buildings in the last decade has led to more efficient usage of renewable energy. Building integrated photovoltaic/thermal systems is one of the effective ways of reducing energy consumption in buildings by providing heating, cooling, ventilation, hot water, and air. The enhancement of photovoltaic cell temperature reduces the electrical efficiency of photovoltaic panel systems. In this regard, the effects of cooling with air and phase change material layer are investigated in this study. The simulation of BIPV/T, PV, and heat pump was done in TRNSYS. As the main novelty of recent simulation, for the calculations of phase change material layer, MATLAB coupled with the TRNSYS, and Python software was used for the prediction process under the weather conditions of Sharurah, Saudi Arabia for 2022. Also, the performance of a building integrated photovoltaic/thermal system with a phase change material layer is predicted for 2024 and 2025 by the Random Forest machine learning method. The R squared, Root Mean Squared Error, and Mean Absolute Error are utilized for checking the accuracy of the model. Also, for more certainty, a validation was done on the simulated results of TRNSYS and the results showed high conformity of data. The simulated data for the first six months of 2022 showed that the maximum cooling effect happened in June with 25.47 °C and a 37.87 % reduction in photovoltaic cell temperature. Also, the best electrical efficiency improvement was 1.26 % while the thermal efficiency ranged from 29.65 % to 59.40 %, respectively. The predicted data was confirmed by R2, RMSE, and MAE equal to 96.64 %, 0.06 and 0.04. According to the simulation and predictions done, the annual electrical production of the building is achieved. The results indicate that, for the simulated system, about 29.7 %, 29.8 %, and 29.6 % of total energy utilization could be supplied by BIPV/T cooled with phase change material in 2022, 2024, and 2025, respectively.

Performance Assessment of Confined Tube Aerators in Parallel Configuration

Aeration plays a major role in the activated-sludge wastewater treatment process. Microbes require an oxygen-enriched environment to digest organic materials and remove nutrients from the wastewater stream. For providing this oxygen, artificial aeration is required, which is responsible for the majority of energy use in treatment plants. Typically, this is accomplished with diffused aerators, where pressurized air is forced through a porous medium at the bottom of deep basins, and bubbles float up through the water column transferring oxygen in the process. This is a relatively energy-intensive process, which is prone to fouling at the porous media. In this study, a Confined Tube Aeration (CTA) system is proposed, where a pump forces water through a Venturi injector, where air is naturally drawn in. At the Venturi discharge, the flow is diverted to a coiled tube in which oxygen transfer occurs. This study analyzes the effect of parallelizing the CTA system with multiple injectors and at varying pump speeds (flow rates). Using experimental and analytical means, the maximum standard aeration efficiency was found to be with three injectors in parallel, at maximum pump speed, and utilizing a CTA with diameter 31.75 mm and length 3.048 m. This value was found to be 0.542 kg O2/kWh, and represents a 25% increase over the single-injector case. Although the analyses herein utilize a relatively small (0.746 kW) pump, these results indicate that CTA systems may scale well to larger pump sizes necessary for full-scale municipal wastewater treatment.

Optimal Control Allocation for Distributed Electric Propulsion in a Series/Parallel Partial Hybrid Powertrain

Abstract The SUbsonic Single Aft eNgine (SUSAN) Electrofan is a NASA concept transport aircraft representative of technology anticipated for a 2040 entry-into-service date. The powertrain consists of a single thrust-producing geared turbofan engine with generators driving a series/parallel partial hybrid power/propulsion system. The architecture includes 16 underwing contrarotating fans, eight on each side. The distributed fans can be used by the flight control system to augment or replace the rudder function. This paper sets up the optimal control problem of setpoint determination for individual wingfans in the distributed propulsion system, accounting for electrical string efficiencies, saturations, and failures. The solution minimizes power consumption while maintaining thrust and torque on the airframe for maneuvering. Additionally, thrust that would have been lost due to temporary fan speed or power saturation is optimally redistributed to maintain overall desired thrust and torque on the aircraft. A simulation of a coordinated turn utilizing the distributed electric propulsion for yaw rate control in a multiple wingfan failure scenario demonstrates the robustness of the powertrain design to failures and helps define its limitations.

Hydrogen Generation by Nickel Electrodes Coated with Linear Patterns of PTFE

Previous studies have shown that partially coating electrode surfaces with patterns of ‘islands’ of hydrophobic tetrafluoroethylene (PTFE; Teflon) may lead to more energy efficient gas generation. This occurred because the gas bubbles formed preferentially on the PTFE, thereby freeing up the catalytically active metallic surfaces to produce the gas more efficiently. This work examined electrochemically induced hydrogen bubble formation on a nickel electrode surface that had been coated with linear patterns of PTFE. The impact of the PTFE line size (width) and degree of coverage was examined and analyzed. No improvement in electrical energy efficiency was observed up to 15 mA/cm2 when comparing the PTFE-coated electrodes with the control bare uncoated electrode. However, increasing PTFE coverage up to 15% generally improved electrolysis performance. Moreover, samples with 50% wider lines performed better (at the equivalent PTFE coverage), yielding an overpotential decline of up to 3.9% depending on the PTFE coverage. A ‘bubble-scavenging’ phenomenon was also observed, wherein bubbles present on the PTFE lines rapidly shrunk until they disappeared.

Energy and exergy analysis of a parabolic trough driven an ORC cycle for heat and power supply

Converting solar energy using the Parabolic Trough Collector (PTC) to produce electrical energy and supply industrial heat is one of the most prominent and most popular sustainable and renewable, widely used throughout the worldwide due to its effectiveness and benefit returns. For this reason, this study aims to investigate the effectiveness of these power plants under a specific climatic conditions and analysis the results come out from the simulation using an EES developed model. The analysis investigates the energy and exergy of the PTC plant coupled with Turboden ORC cycle. The presented model allows us to preview the theoretical results and derive the expected results smoothly, with the possibility of development for a better control of the use of renewable energies in the industrial field. The thermal efficiency of the ORC cycle increases as the heat output increases until it reaches an almost constant value above 2801 [kW] in heat output with a output capacity of the ORC cycle about 1 [MW].

Performance Assessment of Hybrid PV/PVT Collectors Incorporating Natural Water-Cooling Circulation

The present work investigates outdoor recitals and characteristics of hybrid PVT collectors and compares using non-cooled Photo-Voltaic (PV) collectors on a clear day at Khamshet, Pune, India. The hybrid PVT is designed, fabricated, and mounted on the terraces of the institute to ensure maximum radiation will fall on PV and PVT collector. The spiral circular thermal absorber is manufactured and placed at the backside of the photovoltaic to lower the surface temperature by extracting heat through water flowing through the absorber. The experimentation is performed at 0.03 kg/sec of water and natural cooling circulation is adopted for experimental work. The uncertainty analysis is also performed to ensure the accuracy of the results. The investigation observed that the PVT collector is superior to the PV system from electrical and thermal efficiency viewpoints. The cutback in PV module temperature was observed in a variation of 8.7-13.7%, which justifies using the water-cooling technique. The maximum electrical and thermal efficiency of 6.93 % and 52.7% were found for PVT collectors while sole maximum electrical efficiency of 5.62 % was found for PV collectors. This study concludes that the PVT collector has better performance characteristics than the PV collector and can be further enhanced using different fluid and thermal absorber designs.