Applied Sciences

2024

Jump to: 2022, 2021

18 pages, 321 KiB

Open AccessArticle

Re-Imagining Trade Policy and Energy Efficiency: Groundbreaking Pathways to Strengthen Environmental Sustainability in South Korea

by Dongxue Wang and Yugang He

Appl. Sci. 2024, 14(20), 9443; https://doi.org/10.3390/app14209443 - 16 Oct 2024

Viewed by 1025

Abstract

This study explores the long-term interplay between trade policy, energy efficiency, and carbon dioxide (CO₂) emissions in South Korea, using data spanning from 1985 to 2023. By applying the Fourier autoregressive distributed lag (FARDL) model, the analysis reveals that while trade [...] Read more.

This study explores the long-term interplay between trade policy, energy efficiency, and carbon dioxide (CO₂) emissions in South Korea, using data spanning from 1985 to 2023. By applying the Fourier autoregressive distributed lag (FARDL) model, the analysis reveals that while trade liberalization initially leads to a 0.23% increase in CO₂ emissions for each 1% rise in trade openness—driven by the energy demands of industrial expansion—integrating energy efficiency standards within trade agreements helps mitigate these effects over time; this results in a 0.26% reduction in emissions for every 1% improvement in energy efficiency. The study also highlights the dual role of foreign direct investment (FDI), which contributes to a short-term 0.08% rise in emissions but significantly reduces carbon intensity in the long term by facilitating the adoption of cleaner technologies. These findings underscore the importance of innovation and FDI in decoupling economic growth from environmental degradation. The study advocates for the incorporation of energy efficiency measures into trade agreements and the prioritization of green technologies, recommending strategies that could enable South Korea to reduce its CO₂ emissions by up to 40% by 2030. This research positions South Korea as a key actor in achieving global climate goals while maintaining economic competitiveness, offering valuable insights into the balance between sustainable development and industrial growth. Full article

19 pages, 769 KiB

Open AccessArticle

Promoting Environmental Sustainability: The Role of Renewable Energy Systems and Environmental Taxes

by Yugang He

Appl. Sci. 2024, 14(16), 7404; https://doi.org/10.3390/app14167404 - 22 Aug 2024

Viewed by 1851

Abstract

This study examines the effects of renewable energy consumption and environmental taxes on CO₂ emissions in OECD countries from 1990 to 2022, employing the cross-sectional autoregressive distributed lag (CS-ARDL) approach. The findings reveal that both renewable energy consumption and environmental taxes significantly [...] Read more.

This study examines the effects of renewable energy consumption and environmental taxes on CO₂ emissions in OECD countries from 1990 to 2022, employing the cross-sectional autoregressive distributed lag (CS-ARDL) approach. The findings reveal that both renewable energy consumption and environmental taxes significantly reduce CO₂ emissions in both the short and the long term, emphasizing their crucial roles in climate change mitigation and sustainability promotion. Furthermore, this study identifies that industrialization and urbanization contribute to increased emissions, whereas foreign direct investment aids in emission reduction through the facilitation of green technology transfer. Economic growth is initially associated with higher emissions, but this trend reverses as economies mature and adopt sustainable practices. These results highlight the importance of continuous investment in renewable energy infrastructure and the implementation of robust environmental tax policies to achieve long-term sustainability goals. The integration of environmental considerations into economic and urban planning, along with leveraging foreign direct investment for technological advancements, is imperative for balancing economic growth with the necessity to reduce carbon emissions and effectively address climate change. This research provides a better understanding of the diverse factors influencing CO₂ emissions and offers critical insights for policymakers. Full article

2022

Jump to: 2024, 2021

15 pages, 2618 KiB

Open AccessArticle

Development and Opportunities of Clean Energy in China

by Jin Han and Hongmei Chang

Appl. Sci. 2022, 12(9), 4783; https://doi.org/10.3390/app12094783 - 9 May 2022

Cited by 27 | Viewed by 3584

Abstract

In the context of the energy crisis and global climate deterioration, the sustainable development of clean energy will become a new direction for future energy development. Based on the development process of clean energy in China in the past ten years, this paper [...] Read more.

In the context of the energy crisis and global climate deterioration, the sustainable development of clean energy will become a new direction for future energy development. Based on the development process of clean energy in China in the past ten years, this paper expounds on China’s clean energy policy and development plan. The development of hydropower, wind power, and solar power in China in recent years is analyzed. On this basis, the Grey Forecasting Model is used to forecast the development and structure of China’s clean energy in the next 10 years, point out the direction and market opportunities of China’s clean energy development in the future, and put forward the implementation methods for the sustainable development of China’s clean energy. It provides a reference for the policy decision-making of China’s clean energy development. Full article

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16 pages, 3190 KiB

Open AccessArticle

Heat Transfer Analysis of the Flat Plate Solar Thermal Collectors with Elliptical and Circular Serpentine Tubes

by Shirin Rostami, Ag Sufiyan Abd Hamid, Kamaruzzaman Sopian, Hasila Jarimi, Anwor Bassim and Adnan Ibrahim

Appl. Sci. 2022, 12(9), 4519; https://doi.org/10.3390/app12094519 - 29 Apr 2022

Cited by 6 | Viewed by 3821

Abstract

In this study, the heat transfer characteristics of the flat plate collectors with circular and elliptical serpentine tubes are theoretically analyzed and compared in terms of

\dot{m}

,

R e

,

N u

,

h_{f i}

,

F_{R}

, [...] Read more.

In this study, the heat transfer characteristics of the flat plate collectors with circular and elliptical serpentine tubes are theoretically analyzed and compared in terms of

\dot{m}

,

R e

,

N u

,

h_{f i}

,

F_{R}

,

Q_{u}

, and

μ_{T h}

under various water flow rates and the standard test conditions. The results reveal that the maximum

μ_{T h}

correspondence to the elliptical serpentine design with 56% under turbulent flow, and the minimum

μ_{T h}

of 47% for the circular cross-section under laminar flow. In addition, it was found that the highest useful energy gain per unit time (493.8 W) through the system is possible when

F_{R}

,

h_{f i}

,

N u

, and

\dot{m}

are maximum and vice versa. It was concluded that, at the same area, the larger contact area in the elliptical cross-section compared to the circular would improve

F_{R}

and

Q_{u}

by an average of 2%. Overall, it is crucial to evaluate the thermal parameters of the thermal collector during the preliminary design stage to fabricate a highly efficient system and save time as well as initial cost. Full article

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19 pages, 5020 KiB

Open AccessFeature PaperArticle

Solar Irradiance Forecasting Using Dynamic Ensemble Selection

by Domingos S. de O. Santos, Jr., Paulo S. G. de Mattos Neto, João F. L. de Oliveira, Hugo Valadares Siqueira, Tathiana Mikamura Barchi, Aranildo R. Lima, Francisco Madeiro, Douglas A. P. Dantas, Attilio Converti, Alex C. Pereira, José Bione de Melo Filho and Manoel H. N. Marinho

Appl. Sci. 2022, 12(7), 3510; https://doi.org/10.3390/app12073510 - 30 Mar 2022

Cited by 25 | Viewed by 3785

Abstract

Solar irradiance forecasting has been an essential topic in renewable energy generation. Forecasting is an important task because it can improve the planning and operation of photovoltaic systems, resulting in economic advantages. Traditionally, single models are employed in this task. However, issues regarding [...] Read more.

Solar irradiance forecasting has been an essential topic in renewable energy generation. Forecasting is an important task because it can improve the planning and operation of photovoltaic systems, resulting in economic advantages. Traditionally, single models are employed in this task. However, issues regarding the selection of an inappropriate model, misspecification, or the presence of random fluctuations in the solar irradiance series can result in this approach underperforming. This paper proposes a heterogeneous ensemble dynamic selection model, named HetDS, to forecast solar irradiance. For each unseen test pattern, HetDS chooses the most suitable forecasting model based on a pool of seven well-known literature methods: ARIMA, support vector regression (SVR), multilayer perceptron neural network (MLP), extreme learning machine (ELM), deep belief network (DBN), random forest (RF), and gradient boosting (GB). The experimental evaluation was performed with four data sets of hourly solar irradiance measurements in Brazil. The proposed model attained an overall accuracy that is superior to the single models in terms of five well-known error metrics. Full article

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16 pages, 3870 KiB

Open AccessArticle

Prediction Model for the Performance of Different PV Modules Using Artificial Neural Networks

by Mahmoud Jaber, Ag Sufiyan Abd Hamid, Kamaruzzaman Sopian, Ahmad Fazlizan and Adnan Ibrahim

Appl. Sci. 2022, 12(7), 3349; https://doi.org/10.3390/app12073349 - 25 Mar 2022

Cited by 15 | Viewed by 2627

Abstract

This study presents a prediction model for comparing the performance of six different photovoltaic (PV) modules using artificial neural networks (ANNs), with simple inputs for the model. Cell temperature (T_c), irradiance, fill factor (FF), short circuit current (I_sc), open-circuit [...] Read more.

This study presents a prediction model for comparing the performance of six different photovoltaic (PV) modules using artificial neural networks (ANNs), with simple inputs for the model. Cell temperature (T_c), irradiance, fill factor (FF), short circuit current (I_sc), open-circuit voltage (V_oc), maximum power (P_m), and the product of V_oc and I_sc are the inputs of the neural networks’ processes. A Prova 1011 solar system analyzer was used to extract the datasets of IV curves for six different PV modules under test conditions. As for the result, the highest FF was the mono-crystalline with an average of 0.737, while the lowest was the CIGS module with an average of 0.66. As for efficiency, the most efficient was the mono-crystalline module with an average of 10.32%, while the least was the thin-film module with an average of 7.65%. It is noted that the thin-film and flexible mono-modules have similar performances. The results from the proposed model give a clear idea about the best and worst performances of the PV modules under test conditions. Comparing the prediction process with the real dataset for the PV modules, the prediction accuracy for the model has a mean absolute percentage error (MAPE) of 0.874%, with an average root mean square error (RMSE) and mean absolute deviation (MAD) of, respectively, 0.0638 A and 0.237 A. The accuracy of the proposed model proved its efficiency for predicting the performance of the six PV modules. Full article

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13 pages, 2648 KiB

Open AccessArticle

Passive and Active Solar Systems in Eco-Architecture and Eco-Urban Planning

by Anna Zaręba, Alicja Krzemińska, Renata Kozik, Mariusz Adynkiewicz-Piragas and Katarina Kristiánová

Appl. Sci. 2022, 12(6), 3095; https://doi.org/10.3390/app12063095 - 17 Mar 2022

Cited by 8 | Viewed by 3988

Abstract

The subject of this article is a presentation of multi-scale passive and active solar and shading systems in urban areas. This research assumes the hypothesis that insolation systems are interdependent and that their integration in urbanized space affects the city biome. Attention has [...] Read more.

The subject of this article is a presentation of multi-scale passive and active solar and shading systems in urban areas. This research assumes the hypothesis that insolation systems are interdependent and that their integration in urbanized space affects the city biome. Attention has been paid to the role of innovative solutions used in the field of ur ban insolation, such as heliostats in the development of future eco-architecture and eco-urban planning. This research has been based on the assumption that only by taking into account the close symbiosis between an energy-efficient building and its appropriate insolation, in combination with properly planned surroundings, it is possible to actually achieve the principles of sustainable development in the urban fabric. The analytical part concerns detailed investigation into solutions in the field of passive and active solar architecture and urban planning, regarding both insolation and shading. The article analyzes source materials, includes descriptions of case studies, and presents a comparative analysis of passive and active solar and shading systems. The research method, both empirically and theoretically, is closely related to case study analysis and has involved collecting and systematizing data on micro and macro “solar” design systems. Full article

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14 pages, 1027 KiB

Open AccessArticle

Assessment of Impacts of Climate Change on Hydropower-Dominated Power System—The Case of Ethiopia

by Tewodros Walle Mekonnen, Solomon Tesfamariam Teferi, Fitsum Salehu Kebede and Gabrial Anandarajah

Appl. Sci. 2022, 12(4), 1954; https://doi.org/10.3390/app12041954 - 13 Feb 2022

Cited by 13 | Viewed by 4758

Abstract

The Ethiopia energy mix is dominated by hydro-generation, which is largely reliant on water resources and their availability. This article aims to examine the impacts of severe drought on electric power generation by developing a Drought Scenario. OSeMOSYS (an open source energy modelling [...] Read more.

The Ethiopia energy mix is dominated by hydro-generation, which is largely reliant on water resources and their availability. This article aims to examine the impacts of severe drought on electric power generation by developing a Drought Scenario. OSeMOSYS (an open source energy modelling tool) was used to perform the analyses. The results were then compared with an existing reference scenario called “New Policy Scenario”. The study looked at how power generation and CO₂ emissions would be altered in the future if reservoir capacity was halved due to drought. Taking this into account, the renewable energy share decreased from its 90% in 2050 to 81% in 2065, which had been 98% to 89% in the case of New Policy Scenario. In another case, CO₂ emissions also increased from 0.42 Mt CO₂ in 2015 to 7.3 Mt CO₂ in 2065, a 3.3 Mt CO₂ increase as compared to the New Scenario. The results showed how a prolonged period of drought would reduce the river flows and lead to an energy transition that may necessitate the installation of other concurrent alternative power plants. The study suggested ways to approach energy mix, particularly for countries with hydro-dominated power generation and those experiencing drought. Full article

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16 pages, 3160 KiB

Open AccessArticle

The Usefulness and Limitations of Ultrasonic Lamb Waves in Preventing the Failure of the Wind Turbine Blades

by Lina Draudvilienė, Asta Meškuotienė, Renaldas Raišutis, Paulius Griškevičius, Žaneta Stasiškienė and Egidijus Žukauskas

Appl. Sci. 2022, 12(4), 1773; https://doi.org/10.3390/app12041773 - 9 Feb 2022

Cited by 5 | Viewed by 2185

Abstract

The Lamb waves are named one of the promising solutions for future wind turbine blade (WTB) failure prevention. The compliance with safety assurance of WTBs by detecting structural changes during the manufacture and performing their monitoring during the service life are effective tools [...] Read more.

The Lamb waves are named one of the promising solutions for future wind turbine blade (WTB) failure prevention. The compliance with safety assurance of WTBs by detecting structural changes during the manufacture and performing their monitoring during the service life are effective tools for environmental sustainability. This work presents the basic characteristics of Lamb waves and highlights two main unusual limitations—the dispersion and an infinite number of modes—as a great challenge that complicates the application of such waves. This requires the investigation and development of new signal processing methods (SPMs) for conducting accuracy assessments according to the requirements of ISO 17025. The general principles for the accuracy assessment of the signal processing methods applied to evaluate the dispersion of Lamb waves are presented here, and a suitable procedure for estimation of errors and uncertainties is proposed. These should facilitate the verification analysis of any signal processing method used for the dispersion evaluation of Lamb waves. This information allows determining parameters that define the measurement reliability and facilitates the application and utilisation of the proposed methods and their choice. Moreover, it is a necessary prerequisite for setting reliable testing, inspecting, and monitoring standards for WTBs certification. Full article

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14 pages, 1941 KiB

Open AccessArticle

Citizens’ Behavior as a Driver of Energy Transition and Greening of the Economy in the Russian Arctic: Findings of a Sociological Survey in the Murmansk Region and Karelia

by Sergey Tishkov, Arsen Tleppayev, Valentina Karginova-Gubinova, Alexander Volkov and Anton Shcherbak

Appl. Sci. 2022, 12(3), 1460; https://doi.org/10.3390/app12031460 - 29 Jan 2022

Cited by 6 | Viewed by 2172

Abstract

Due to the depletion of traditional energy sources, the rising costs of their operation and the need to transition to a sustainable economy, it becomes relevant to increase the share of renewable energy sources in total consumption. The purpose of this study is [...] Read more.

Due to the depletion of traditional energy sources, the rising costs of their operation and the need to transition to a sustainable economy, it becomes relevant to increase the share of renewable energy sources in total consumption. The purpose of this study is to determine the role of renewable energy and the establishment of factors determining pro-environmental behavior. The data of the author’s sociological survey of the population of the Arctic regions of Russia and methods of descriptive statistics were used, and regression analysis was carried out. The study shows the ecological and energy characteristics of the Arctic regions of Russia. The main advantages and possibilities of transition to renewable energy sources have been identified. A relationship has been established between the degree of involvement in pro-environmental behavior and knowledge about renewable energy, the perceived importance of environmental problems, age, income, education, amount of waste produced and current electricity costs. It is shown that the degree of involvement in pro-environmental behavior affects the willingness to pay more for renewable energy. A number of institutional measures to promote renewable energy, increase willingness to pay for renewable energy and spread pro-environmental behavior are proposed. Full article

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11 pages, 3238 KiB

Open AccessArticle

Simulation Model of PV Module Built from Point-Focusing Fresnel Radiation Concentrators and Three-Junction High-Performance Cells

by Mariusz T. Sarniak

Appl. Sci. 2022, 12(2), 806; https://doi.org/10.3390/app12020806 - 13 Jan 2022

Cited by 1 | Viewed by 1601

Abstract

The silicon photovoltaic modules that dominate the market today are constantly being modified, but at the same time, the search for new, more efficient design solutions is underway. The study examined a less popular photovoltaic module built from point-focusing Fresnel radiation concentrators and [...] Read more.

The silicon photovoltaic modules that dominate the market today are constantly being modified, but at the same time, the search for new, more efficient design solutions is underway. The study examined a less popular photovoltaic module built from point-focusing Fresnel radiation concentrators and high-efficiency three-junction cells. The advantage of this type of module is its high overall efficiency, exceeding 30%. The disadvantage is that they require biaxial precision tracking mechanisms because even a small deviation of the direction of direct solar radiation from the perpendicular to the module’s surface causes a large and abrupt drop in efficiency. This type of photovoltaic module structure is often also marked with the symbol C3PV. A mathematical model and simulation calculations were carried out in the Matlab/Simulink package for the C3PV module—the CX-75/200 model based on the “Solar Cell” component. The concentration of direct solar radiation was taken into account. For the module under consideration, experimental and simulation results show the necessity of accurate positioning concerning the direction of solar radiation—deviation of the radiation angle by about 5° causes a very high power loss (by about 92%). Full article

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16 pages, 1858 KiB

Open AccessArticle

Modeling Joule Heating Effect on Thermal Efficiency of Photovoltaic Thermal (PVT) Collectors with Operation Mode Factor (OMF)

by Erkata Yandri

Appl. Sci. 2022, 12(2), 742; https://doi.org/10.3390/app12020742 - 12 Jan 2022

Cited by 1 | Viewed by 3035

Abstract

The purpose of the present study is developing the operation mode factor (OMF) by remodeling the thermal efficiency model of a hybrid PVT collector during steady state. Joule heating occurs when the photovoltaic (PV) panel operates at a high current during maximum power [...] Read more.

The purpose of the present study is developing the operation mode factor (OMF) by remodeling the thermal efficiency model of a hybrid PVT collector during steady state. Joule heating occurs when the photovoltaic (PV) panel operates at a high current during maximum power point tracking (MPPT) on higher irradiation. Under these conditions, some electrical energy converts to thermal energy within the PV cells. Joule heating contributed to increasing the PVT thermal efficiency. The steps were to construct the OMF by remodeling the thermal efficiency involving the Joule heating effect and to validate the results using the model by comparing the simulation and experiment. The dimensionless OMF was responsible for changes in thermal efficiency for PVT-mode. The conductive heat transfer coefficient from the surface to the absorber was the most decisive component in the OMF. Heat removal factor and OMF might be interrelated at the mass flow rate by decreasing PV temperature to maintain Joule heating. The proposed model with OMF had explained PVT-mode and T-mode with the RMS value of less than 1%. This model complemented the results of the previous studies. The results may contribute from the initial design to the operational monitoring for thermal to electrical energy production. Full article

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2021

Jump to: 2024, 2022

19 pages, 5483 KiB

Open AccessArticle

Heat Transfer of Nanomaterial over an Infinite Disk with Marangoni Convection: A Modified Fourier’s Heat Flux Model for Solar Thermal System Applications

by Mahanthesh Basavarajappa, Giulio Lorenzini, Srikantha Narasimhamurthy, Ashwag Albakri and Taseer Muhammad

Appl. Sci. 2021, 11(24), 11609; https://doi.org/10.3390/app112411609 - 7 Dec 2021

Cited by 5 | Viewed by 2168

Abstract

The demand for energy due to the population boom, together with the harmful consequences of fossil fuels, makes it essential to explore renewable thermal energy. Solar Thermal Systems (STS’s) are important alternatives to conventional fossil fuels, owing to their ability to convert solar [...] Read more.

The demand for energy due to the population boom, together with the harmful consequences of fossil fuels, makes it essential to explore renewable thermal energy. Solar Thermal Systems (STS’s) are important alternatives to conventional fossil fuels, owing to their ability to convert solar thermal energy into heat and electricity. However, improving the efficiency of solar thermal systems is the biggest challenge for researchers. Nanomaterial is an effective technique for improving the efficiency of STS’s by using nanomaterials as working fluids. Therefore, the present theoretical study aims to explore the thermal energy characteristics of the flow of nanomaterials generated by the surface gradient (Marangoni convection) on a disk surface subjected to two different thermal energy modulations. Instead of the conventional Fourier heat flux law to examine heat transfer characteristics, the Cattaneo–Christov heat flux (Fourier’s heat flux model) law is accounted for. The inhomogeneous nanomaterial model is used in mathematical modeling. The exponential form of thermal energy modulations is incorporated. The finite-difference technique along with Richardson extrapolation is used to treat the governing problem. The effects of the key parameters on flow distributions were analyzed in detail. Numerical calculations were performed to obtain correlations giving the reduced Nusselt number and the reduced Sherwood number in terms of relevant key parameters. The heat transfer rate of solar collectors increases due to the Marangoni convection. The thermophoresis phenomenon and chaotic movement of nanoparticles in a working fluid of solar collectors enhance the temperature distribution of the system. Furthermore, the thermal field is enhanced due to the thermal energy modulations. The results find applications in solar thermal exchanger manufacturing processes. Full article

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18 pages, 4144 KiB

Open AccessArticle

Closed-Loop Systems for Geothermal Energy Exploitation from Hydrocarbon Wells: An Italian Case Study

by Martina Gizzi

Appl. Sci. 2021, 11(22), 10551; https://doi.org/10.3390/app112210551 - 9 Nov 2021

Cited by 2 | Viewed by 2338

Abstract

Geothermal energy resources associated with disused hydrocarbon wells in Italian oilfields represent a considerable source of renewable energy. Using the information available on Italian hydrocarbon wells and on-field temperatures, two simplified closed-loop-type systems models were implemented in the Python environment and applied to [...] Read more.

Geothermal energy resources associated with disused hydrocarbon wells in Italian oilfields represent a considerable source of renewable energy. Using the information available on Italian hydrocarbon wells and on-field temperatures, two simplified closed-loop-type systems models were implemented in the Python environment and applied to a selected hydrocarbon well (Trecate4) located inside the Italian Villafortuna–Trecate field (Northwestern Italy). Considering the maximum extracted working fluid temperatures, Coaxial WBHE turned out to be a better performing technology than the U-tube version. The obtained outflow temperatures of the working fluid at the wellhead for Coaxial and U-tube WBHEs of 98.6 °C and 84 °C, respectively, are both potentially exploitable for ensuring a multi-variant and comprehensive use of the resource through its application in sectors such as the food industry, horticultural and flower fields. Full article

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14 pages, 2234 KiB

Open AccessArticle

Hydrates for Cold Storage: Formation Characteristics, Stability, and Promoters

by Huan Chen, Bingyue Han, Chen Lang, Min Wen, Baitao Fan and Zheyuan Liu

Appl. Sci. 2021, 11(21), 10470; https://doi.org/10.3390/app112110470 - 8 Nov 2021

Cited by 8 | Viewed by 2521

Abstract

The potential of hydrates formed from R141b (CH₃CCl₂F), trimethylolethane (TME), and tetra-n-butylammonium bromide/tetra-n-butylammonium chloride (TBAB/TBAC) to be used as working substances for cold storage was investigated to provide a solution for unbalanced energy grids. In this study, the characteristics [...] Read more.

The potential of hydrates formed from R141b (CH₃CCl₂F), trimethylolethane (TME), and tetra-n-butylammonium bromide/tetra-n-butylammonium chloride (TBAB/TBAC) to be used as working substances for cold storage was investigated to provide a solution for unbalanced energy grids. In this study, the characteristics of hydrate formation, crystal morphology of hydrates, and the stability of hydrate in cyclic formation under 0.1 MPa and at 5 °C were carried out. It found that the ice had a positive effect on the hydrate formation under same conditions. Upon the addition of the ice cube, the induction time of R141b, TME, and TBAB/TBAC hydrates decreased markedly, and significantly high formation rates were obtained. Under magnetic stirring, the rate at which TBAB/TBAC formed hydrates was significantly lower than that when ice was used. In microscopic experiments, it was observed that the TBAB/TBAC mixture formed hydrates with more nucleation sites and compact structures, which may increase the hydrate formation rate. In the multiple cycle formation of TBAB/TBAC hydrates, the induction time gradually decreased with the increasing number of formation cycles and finally stabilized, which indicated the potential of the TBAB/TBAC hydrates for application in cold storage owing to their good durability and short process time for heat absorption and release. Full article

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25 pages, 53178 KiB

Open AccessArticle

Exploring the Benefits of Photovoltaic Non-Optimal Orientations in Buildings

by Esteban Sánchez, Ángel Ordóñez, Alberto Sánchez, Raúl García Ovejero and Javier Parra-Domínguez

Appl. Sci. 2021, 11(21), 9954; https://doi.org/10.3390/app11219954 - 25 Oct 2021

Cited by 7 | Viewed by 2814

Abstract

As solar photovoltaics in buildings reaches maturity, grid integration and economic yield are topics of greater interest. The traditional design of photovoltaic installations has considered the optimal orientation of photovoltaic modules to be that which yields the maximum annual energy production. The influence [...] Read more.

As solar photovoltaics in buildings reaches maturity, grid integration and economic yield are topics of greater interest. The traditional design of photovoltaic installations has considered the optimal orientation of photovoltaic modules to be that which yields the maximum annual energy production. The influence of the consumption patterns and the hourly variable electricity prices implies that this traditional optimal design might not be the most profitable. Using a full-year dataset for a residential installation, alternative installations using canopies and modules attached to the façades are simulated. By evaluating the energy balances for different annual consumptions, it is found that the canopy and façade installations offer better self-consumption of the PV produced energy, reflected in a 9% higher self-consumption degree using modules on façades and a 5% higher self-consumption degree using canopies. The economic evaluation under the new electricity tariffs in Spain shows a better profit for PV self-consumption, reducing the time of return on investment by more than 2 years. The analysis of different alternatives for an industrial PV allowed us to identify several benefits for these orientations which are confirmed after a full year of operation, such as an increase of up to 59% in annual energy production over the optimal-producing orientation. Full article

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19 pages, 4445 KiB

Open AccessArticle

Wind Farm Layout Optimization with Different Hub Heights in Manjil Wind Farm Using Particle Swarm Optimization

by Menova Yeghikian, Abolfazl Ahmadi, Reza Dashti, Farbod Esmaeilion, Alireza Mahmoudan, Siamak Hoseinzadeh and Davide Astiaso Garcia

Appl. Sci. 2021, 11(20), 9746; https://doi.org/10.3390/app11209746 - 19 Oct 2021

Cited by 19 | Viewed by 3161

Abstract

Nowadays, optimizing wind farm configurations is one of the biggest concerns for energy communities. The ongoing investigations have so far helped increasing power generation and reducing corresponding costs. The primary objective of this study is to optimize a wind farm layout in Manjil, [...] Read more.

Nowadays, optimizing wind farm configurations is one of the biggest concerns for energy communities. The ongoing investigations have so far helped increasing power generation and reducing corresponding costs. The primary objective of this study is to optimize a wind farm layout in Manjil, Iran. The optimization procedure aims to find the optimal arrangement of this wind farm and the best values for the hubs of its wind turbines. By considering wind regimes and geographic data of the considered area, and using the Jensen’s method, the wind turbine wake effect of the proposed configuration is simulated. The objective function in the optimization problem is set in such a way to find the optimal arrangement of the wind turbines as well as electricity generation costs, based on the Mossetti cost function, by implementing the particle swarm optimization (PSO) algorithm. The results reveal that optimizing the given wind farm leads to a 10.75% increase in power generation capacity and a 9.42% reduction in its corresponding cost. Full article

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24 pages, 6071 KiB

Open AccessArticle

Geometric Analysis through the Constructal Design of a Sea Wave Energy Converter with Several Coupled Hydropneumatic Chambers Considering the Oscillating Water Column Operating Principle

by Yuri Theodoro Barbosa de Lima, Mateus das Neves Gomes, Liércio André Isoldi, Elizaldo Domingues dos Santos, Giulio Lorenzini and Luiz Alberto Oliveira Rocha

Appl. Sci. 2021, 11(18), 8630; https://doi.org/10.3390/app11188630 - 16 Sep 2021

Cited by 11 | Viewed by 2023

Abstract

The work presents a numerical study of a wave energy converter (WEC) device based on the oscillating water column (OWC) operating principle with a variation of one to five coupled chambers. The main objective is to evaluate the influence of the geometry and [...] Read more.

The work presents a numerical study of a wave energy converter (WEC) device based on the oscillating water column (OWC) operating principle with a variation of one to five coupled chambers. The main objective is to evaluate the influence of the geometry and the number of coupled chambers to maximize the available hydropneumatic power converted in the energy extraction process. The results were analyzed using the data obtained for hydropneumatic power, pressure, mass flow rate, and the calculated performance indicator’s hydropneumatic power. The Constructal Design method associated with the Exhaustive Search optimization method was used to maximize the performance indicator and determine the optimized geometric configurations. The degrees of freedom analyzed were the ratios between the height and length of the hydropneumatic chambers. A wave tank represents the computational domain. The OWC device is positioned inside it, subject to the regular incident waves. Conservation equations of mass and momentum and one equation for the transport of the water volume fraction are solved with the finite volume method (FVM). The multiphase model volume of fluid (VOF) is used to tackle the water–air mixture. The analysis of the results took place by evaluating the performance indicator in each chamber separately and determining the accumulated power, which represents the sum of all the powers calculated in all chambers. The turbine was ignored, i.e., only the duct without it was analyzed. It was found that, among the cases examined, the device with five coupled chambers converts more energy than others and that there is an inflection point in the performance indicator, hydropneumatic power, as the value of the degree of freedom increases, characterizing a decrease in the value of the performance indicator. With the results of the hydropneumatic power, pressure, and mass flow rate, it was possible to determine a range of geometry values that maximizes the energy conversion, taking into account the cases of one to five coupled chambers and the individual influence of each one. Full article

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24 pages, 1559 KiB

Open AccessArticle

Carbon Lock-In and Contradictions—Applied Guide to Academic Teaching of Mexico’s Energy Transition

by Ariel Macaspac Hernandez, Daniel Alejandro Pacheco Rojas and Diana Barrón Villaverde

Appl. Sci. 2021, 11(18), 8289; https://doi.org/10.3390/app11188289 - 7 Sep 2021

Cited by 5 | Viewed by 4391

Abstract

The energy sector plays an important role in Mexico’s development trajectory. Mexico makes an interesting case study because it shows how difficult it is to reduce fossil energy dependence despite geographic and climatic conditions that favour renewable energy deployment and use. Resolving path [...] Read more.

The energy sector plays an important role in Mexico’s development trajectory. Mexico makes an interesting case study because it shows how difficult it is to reduce fossil energy dependence despite geographic and climatic conditions that favour renewable energy deployment and use. Resolving path dependencies and the related carbon lock-in are key to Mexico’s sustainable energy transition. This applied teaching guide contemplates the use of a case-illustration typology to identify and discuss how the politics about carbon lock-in affects Mexico’s sustainable energy transition. This methodology is an innovative endeavour that aims to apply the case study in classrooms with the intention to encourage discussions and solution-oriented approaches when tangible actions are identified by the educator and students. This methodology elevates the case study to a “living” case study that leads to recommended actions. The applied teaching guide allows educators, who are mostly researchers, to reflect on how Mexico’s case study could be explained not only to promote the students’ understanding of the challenges, but also to provide educators/researchers the skills on how to effectively disseminate knowledge. Mexico’s carbon lock-in involves oil and oil-run power plants that are costly to build but relatively inexpensive to operate. To conclude, this case study identifies potential entry points for transitioning towards sustainable energy in Mexico—resources that can promote the use of clean energy despite carbon lock-in. For example, focusing on electrification—particularly the carbon-intensive sectors—can help Mexico transit towards sustainable energy despite institutional constraints. Complementing this case study is a teaching guide with recommendations for using Mexico’s energy transition in courses on sustainability. By understanding how to explain the case study, the educator/researcher can better structure the complexity of the case study. This approach introduces a “learning activation framework” to identify emerging opportunities that can advance sustainable energy transitions in different cases of carbon lock-in. The framework also gives students a chance to help dismantle or cope with carbon lock-ins. Mexico’s energy transition makes a valuable teaching example because its energy transition is part of a broader developmental goal. This teaching guide’s systematic approach can maximise the students’ learning experience. Full article

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18 pages, 5317 KiB

Open AccessFeature PaperArticle

Application of Simultaneous Symmetric and Cambered Airfoils in Novel Vertical Axis Wind Turbines

by Sajad Maleki Dastjerdi, Kobra Gharali, Armughan Al-Haq and Jatin Nathwani

Appl. Sci. 2021, 11(17), 8011; https://doi.org/10.3390/app11178011 - 30 Aug 2021

Cited by 8 | Viewed by 2934

Abstract

Two novel four-blade H-darrieus vertical axis wind turbines (VAWTs) have been proposed for enhancing self-start capability and power production. The two different airfoil types for the turbines are assessed: a cambered S815 airfoil and a symmetric NACA0018 airfoil. For the first novel wind [...] Read more.

Two novel four-blade H-darrieus vertical axis wind turbines (VAWTs) have been proposed for enhancing self-start capability and power production. The two different airfoil types for the turbines are assessed: a cambered S815 airfoil and a symmetric NACA0018 airfoil. For the first novel wind turbine configuration, the Non-Similar Airfoils 1 (NSA-1), two NACA0018 airfoils, and two S815 airfoils are opposite to each other. For the second novel configuration (NSA-2), each of the S815 airfoils is opposite to one NACA0018 airfoil. Using computational fluid dynamics (CFD) simulations, static and dynamic conditions are evaluated to establish self-starting ability and the power coefficient, respectively. Dynamic stall investigation of each blade of the turbines shows that NACA0018 under dynamic stall impacts the turbine’s performance and the onset of dynamic stall decreases the power coefficient of the turbine significantly. The results show that NSA-2 followed by NSA-1 has good potential to improve the self-starting ability (13.3%) compared to the turbine with symmetric airfoils called HT-NACA0018. In terms of self-starting ability, NSA-2 not only can perform in about 66.67% of 360

°

similar to the wind turbine with non-symmetric airfoils (named HT-S815) but the power coefficient of NSA-2 at the design tip speed ratio of 2.5 is also 4.5 times more than the power coefficient of HT-S815; the power coefficient difference between HT-NACA0018 and HT-S815 (=0.231) is decreased significantly when HT-S815 is replaced by NSA-2 (=0.076). These novel wind turbines are also simple. Full article

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