Energy Conversion and Management-X最新文献

This study provides a comprehensive evaluation of the techno-economic and environmental performance of six hybrid energy systems (HESs) in Kunder Char, Bangladesh, incorporating both conventional (diesel and natural gas) and renewable energy sources (solar and wind). Using HOMER Pro software, a comparative analysis of five off-grid systems and one on-grid system are conducted for assessing their cost-effectiveness, energy efficiencies, and environmental impacts under various sensitivity conditions. After thorough evaluation the on-grid system has emerged as the most economically viable option, with a levelized cost of energy (LCOE) of $0.0436/kWh and a net present cost (NPC) of $1.43 million. It also produced minimal waste energy (0.381 %) but with high CO₂ emissions. In contrast, the PV-Battery setup, though the most expensive with an LCOE of $0.266/kWh and an NPC of $3.36 million, offered the benefit of zero emissions and generated 40 % excess electricity. Sensitivity analyses highlighted the influence of solar radiation (4.45 kWh/m²/day), wind speed (4.81 m/s), and fuel price (Diesel: $1/L) on these systems, providing insights into their operational dynamics under varying environmental and economic scenarios. The findings highlight the trade-offs between cost, sustainability, and efficiency, promoting energy solutions customized to meet the specific needs of remote regions like Kunder Char. This study also helps in understanding the potential of hybrid systems to meet energy demands sustainably in challenging geographical and economic landscapes.

Closed-loop systems enable circular economy systems and applications in the food and beverage sector to enhance decarbonisation. Whiskey distillation by-products are amenable to anaerobic digestion and thus facilitate resource recovery and circularity. Furthermore, biochar derived from whiskey barrels can be used as a carbonaceous additive within anaerobic digestion to enhance biomethane production. In this paper, biochar produced from the pyrolysis of discarded whiskey barrels at 300 °C, was shown to enhance biomethane production by up to 15 %. A kinetic analysis revealed that the biochar reduced the biomethane lag time by up to 42 %. The mass and energy balance of this integrated anaerobic digestion-pyrolysis system was evaluated. The overall system efficiency was assessed at 68 % of all input energy (expressed on a primary energy basis); utilisation of renewable electricity could increase this efficiency to 71 %. Biochar from discarded whiskey barrels can provide a decarbonisation pathway for whiskey distilleries but may be constrained by the total resource available.

SiC-based duplex claddings, consisting of monolithic SiC and SiC/SiC fiber composite, are emerging as a promising candidate for accident-tolerant fuel (ATF) systems in nuclear reactors. To analyze the performance of ATFs with SiC-based duplex claddings, a comprehensive computational analysis framework is presented that captures the essential properties and behaviors of the UO₂-SiC fuel system. Utilizing a previously developed continuum damage model, the pseudo-ductile behavior of SiC/SiC fiber composites is accurately modelled, connecting damage evolution parameters to instantaneous stiffness matrix degradation. This framework is used to investigate the performance of UO₂-SiC fuel rods under normal operating conditions and a typical Loss of Coolant Accident (LOCA) scenario. We assess the effects of the thickness ratio of the monolithic SiC and SiC-based composite layers, as well as pellet-clad cold gap thickness on the failure and leakage probabilities of the cladding. These claddings, with a thickness ratio ranging from 0.25 to 0.75, demonstrated minimal failure and leakage probabilities for both the original and reduced pellet-clad gap thickness (82.5/70 µm). When the gap thickness was further reduced to 57.5 µm, pellet-cladding mechanical interaction was observed and this greatly elevated the failure probability of the MSiC layer, thus giving rise to a loss of hermeticity. This research underscores the significant role of varying individual layer thicknesses in shaping fuel rod safety and offers potential for optimization across diverse operational conditions.

Photovoltaic-thermoelectric hybrid devices aim at harvesting the entire solar spectrum via both direct photovoltaic conversion and subsequent thermoelectric conversion of the heat generated in the solar cell. One emerging strategy to improve their efficiency is to implement a photothermal interface between the photovoltaic cell and the thermoelectric module. Modeling such a complex system (photovoltaic cell, photothermal interface and thermoelectric generator) to design an optimal architecture is a challenging task, as it requires to take into account a large number of parameters in a multi-layered system, as well as the coupling between optical, thermal and electrical effects. To do so, we present here a multiphysics tool to predict the temperature distribution and power output of hybrid devices integrating a photothermal interface. Our model shows a good quantitative agreement with previous theoretical and experimental works from the literature using limited material parameters. We discuss the need for additional parameters for accurate modeling of experimental devices. We envision that our multiphysics modeling tool will be key for the design of optimal photothermal interfaces for efficient photovoltaic-thermoelectric hybrid devices.

Solar drying systems often face the challenge of overheating due to uncontrolled solar collectors, which can degrade the quality of dried products by destroying enzymes, vitamins, and their chemical composition. To address this issue, we developed and validated a new control system for stabilizing drying air temperature using both experimental and CFD numerical methods. This system not only effectively maintains the desired air temperature but also extends the lifespan of solar collectors by adjusting their exposure during periods of excessive solar radiation. The experimental results demonstrated that without the control system, the air temperature peaked at 72 °C, leading to potential product degradation. In contrast, the control system has succeeded in stabilizing the air temperature at an optimum level. Additionally, the validated CFD model confirmed the effectiveness of this control technique in various climatic conditions, including cold semi-arid, typically Mediterranean, hot semi-arid, and sub-desert conditions. The findings underline the importance and necessity of temperature control in solar drying systems, as well as the effectiveness of the CFD method in predicting system performance. Furthermore, this work significantly enhances the efficiency and applicability of solar drying technology, offering a practical solution for improving product quality and system durability.

With the improvement in people’s quality of life, the requirements for health and safety are also increasing. While many wearable devices are available, those wearable devices specifically designed for the safety of night workers have yet to be effectively utilized. A survey conducted with 100 night workers revealed that they have expressed concerns about their safety and that of their colleagues due to lack of visibility while working on the road at night. To address this issue, a wearable electromagnetic energy generator was designed as a permanent solution to increase the visibility of night workers by illuminating LEDs and reduce the discomfort associated with wearable devices. The generator can be integrated with uniforms and converts the kinetic energy generated by the human body during work into electrical power. The generator achieved a maximum output power of 4.28 mW under 2.8 Hz, with a power density is 51.56 μW/cm³. The LED brightness driven by the generator reached 218 Lux. To ensure user customization, the Living Lab strategy was employed, allowing direct user participation during the development process and incorporating improvements based on their feedback. After gathering feedback from the workers, the uniform was redesigned and revised multiple times. Ultimately, the product received high satisfaction scores and was successfully delivered to local municipalities. This paper details a comprehensive study covering the process from needs survey to product design.

The organic Rankine cycle (ORC)−dual cascading vapor compressor cycle (DCVCC) system, being a highly efficient energy utilization technology, possesses significant potential for development. This paper presents a thermodynamic analysis of a new combined ORC and DCVCC system propelled by the solar cycle to produce electric energy and a cooling effect. An exergy-energy evaluation was conducted utilizing six distinct pairs of refrigerants due to their favorable thermodynamic properties, efficiency, environmental considerations, compatibility, safety, and regulatory compliance, namely R245fa-R114, R245fa-R1234yf, R245fa-R1234ze, R245fa-R32, R245fa-R404A, and R245fa-R134a. The fixed refrigerant pair R245fa-R114 is used in the ORC-VCC₁ circuit, while the remaining pairs of refrigerant are used in the VCC₂ circuit. The system modeling is done using the Engineering Equation Solver (EES) program, which takes into account all assumptions, boundary conditions, and inputs as well as the built-in thermodynamic characteristics of various refrigerants in the suggested system models. The findings show that the thermal efficiency of the proposed system exhibits an 84.84% improvement compared to a conventional ORC. This study investigates the influence of thermodynamic parameters, specifically turbine inlet temperature, turbine inlet pressure, and condensing temperature, on the overall performance of the system. The refrigerant pair of R245fa-R32 has a 14.53% higher COP compared to the R245fa-R114 pair when subjected to variations in turbine inlet temperature. A notable enhancement in thermal and exergy efficiency has been reported, exhibiting an increase of 3.03% and 2.03%, respectively, compared to the simple ORC-VCC configuration. The application of R32 in the VCC₂ circuit results in a 63% enhancement in cost-effectiveness as compared to R114. However, low-GWP refrigerants like R1234yf and R1234ze boost COP by 55.45% over R114. In addition, the elevating of the condensing pressure results in a decrease in the COP, thermal efficiency, and net work. Moreover, by finding the most favorable range of evaporator temperature that maximizes the benefits in both cycles, improves system performance characteristics including COP, thermal efficiency, net-work, and refrigerant mass flow rate. For instance, at higher evaporator temperatures the usage of R1234yf, and R1234ze generates approximately 16% higher COP than R114 refrigerant which is making sure the reliability and efficient use of low GWP fluids.

The present investigation examines geothermal and solar energy for electricity generation. The proposed cycle can generate electricity independently or jointly using geothermal and solar sources. Organic Rankine Cycles (ORCs) have been employed due to their positive effects, including improved efficiency, comprehensive performance and economic analysis, adaptability, and the benefits of using ORCs with refrigerants in the hybrid power generation system. The proposed system is designed to include two evaporators, each working at distinct temperature levels, with one running at a high temperature and the other at a low temperature. Consequently, the system is outfitted with a pair of turbines functioning at elevated and moderate pressures. The analysis of the performance of the suggested cycle was conducted considering both energy and exergy perspectives; this leads to the determination of the efficiency of the first and second laws of thermodynamics. As a result, the exergy loss amount was calculated, and the exergy utilization efficiency for each component was determined. To assess the financial implications of the end product, a comprehensive study including electricity and exergy economic factors was conducted. A sensitivity analysis for many different aspects of the design factors and a parametric study, such as the difference in temperature at the pinch point and the temperature of the evaporator and their effects on energy and exergy performance, as well as the cost, are done. Findings revealed that the high-pressure turbine is directly related to the highest second-law efficiency. In contrast, the low-pressure turbine had the highest value for the exergy economic component. The average cost of energy production, obtained by evaluating power generation through low-pressure and high-pressure turbines, was calculated as 27.23 $S/Gj$. The system presented in this article can expand and adapt to diverse case analyses and can be effectively applied under various climatic conditions.

This study presents an experimental investigation into the operational performance of a thermoelectric (TE) freezer system. A freezer unit is composed of two-stage thermoelectric modules, an aluminum plate fin heat exchanger sink with fans positioned either on top or directing airflow through the center, and a cooling block incorporating circulating icy water for heat dissipation. Three distinct configurations, featuring varying numbers of freezer units and fan arrangements, underwent testing using a 300-liter freezer prototype under typical room conditions, specifically at 21 °C. The findings illustrate that the minimum temperature inside the freezer cabinet can achieve −16.0 °C across all configurations. Moreover, the cooling capacity can reach up to 74.7 W, with the thermoelectric coefficient of performance (COP) achieving a maximum of 0.45, while the system COP ranges from 0.23 to 0.28. The minimum TE power consumption and TE system power consumption are recorded at 138.8 W and 174.4 W, respectively, suggesting feasibility for practical residential freezer applications. This investigation sets the stage for the development of TE freezers integrated with ice thermal storage applications.

The quest to develop an appropriate drying technology that is sustainable while minimizing energy losses was the key motivation of this work. In this study, COMSOL multiphysics CFD software was used to model and simulate computational behaviour of a fabricated multipurpose crop dryer equipped with a bio-waste heat source. The generated thermal flow was deployed for drying of paddy rice given the rice drying characteristics. Meanwhile, the drying chamber was finitely discretized into little fragments in order to obtain a better distribution, result and efficiency. The temperature, pressure, and velocity distribution were analysed with simulated optimal drying temperature of paddy rice as 43 °C. This was attained for both simulated and experimented. It was observed that there was higher pressure and velocity at the fan orifice but a decrease as the air moves up the chimney surface as the drying chamber’s average temperature variation required for drying paddy rice was established, with relative error of 0.019 %. The simulated and experimental mean drying chamber efficiency were 90.3 % and 89 % respectively. Therefore, the fabricated multipurpose dryer is a good system for grain drying.