Sustainable Energy Technology, 2nd Edition

Journal Name	Impact Factor	CiteScore	Launched Year	First Decision (median)	APC
Energies energies	3.0	6.2	2008	17.5 Days	CHF 2600	Submit
Sustainability sustainability	3.3	6.8	2009	20 Days	CHF 2400	Submit
Journal of Marine Science and Engineering jmse	2.7	4.4	2013	16.9 Days	CHF 2600	Submit
Processes processes	2.8	5.1	2013	14.4 Days	CHF 2400	Submit
Solar solar	-	-	2021	27.4 Days	CHF 1000	Submit
Wind wind	-	-	2021	43.5 Days	CHF 1000	Submit

21 pages, 10016 KiB

Open AccessArticle

Enhancing Industrial Buildings’ Performance through Informed Decision Making: A Generative Design for Building-Integrated Photovoltaic and Shading System Optimization

by Neri Banti, Cecilia Ciacci, Frida Bazzocchi and Vincenzo Di Naso

Solar 2024, 4(3), 401-421; https://doi.org/10.3390/solar4030018 - 25 Jul 2024

Viewed by 2969

Abstract

The Italian industrial sector contains 22% of the final energy demand due to the poor energy performance of manufacturing buildings. This proposed study aimed to evaluate retrofit interventions for existing industrial buildings integrating photovoltaic solutions into the external envelope to improve both the [...] Read more.

The Italian industrial sector contains 22% of the final energy demand due to the poor energy performance of manufacturing buildings. This proposed study aimed to evaluate retrofit interventions for existing industrial buildings integrating photovoltaic solutions into the external envelope to improve both the environmental sustainability and the facade performance. The methodology is based on an innovative procedure including BIM and generative design tools. Starting from the Revit model of a representative case study, interoperability with energy analysis plugins via Grasshopper were exploited to optimize the differently oriented facade layout of photovoltaic modules to maximize the electricity production. In the case of comparable facade sizes, the building orientation had a minor impact on the results, although a southern exposure was preferable. The optimized configuration involved the installation of PV panels with a tilt angle ranging from −35° to −75°. The best compromise solution between the panel surface area and energy production during the summer solstice involves 466 m² of PV modules. The design-optioneering approach was used to define possible alternatives to be explored for the possible installation of solar shading systems on existing windows. In this case, the impact on visual comfort within the working environment was chosen as a reference parameter, along with the value of the indoor air temperature. A decrease in this parameter equal to 0.46 was registered for the solution with horizontal (or nearly horizontal) shaders and a spacing ranging between 0.2 and 0.4. The integration of the BIM environment with generative design tools effectively assists decision-making processes for the selection of technological solutions in the building sector. Full article

(This article belongs to the Topic Sustainable Energy Technology, 2nd Edition)

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18 pages, 3574 KiB

Open AccessArticle

Prediction of Short-Term Winter Photovoltaic Power Generation Output of Henan Province Using Genetic Algorithm–Backpropagation Neural Network

by Dawei Xia, Ling Li, Buting Zhang, Min Li, Can Wang, Zhijie Gong, Abdulmajid Abdullahi Shagali, Long Jiang and Song Hu

Processes 2024, 12(7), 1516; https://doi.org/10.3390/pr12071516 - 19 Jul 2024

Viewed by 721

Abstract

In the low-carbon era, photovoltaic power generation has emerged as a pivotal focal point. The inherent volatility of photovoltaic power generation poses a substantial challenge to the stability of the power grid, making accurate prediction imperative. Based on the integration of a backpropagation [...] Read more.

In the low-carbon era, photovoltaic power generation has emerged as a pivotal focal point. The inherent volatility of photovoltaic power generation poses a substantial challenge to the stability of the power grid, making accurate prediction imperative. Based on the integration of a backpropagation (BP) neural network and a genetic algorithm (GA), a prediction model was developed that contained two sub-models: no-rain and no-snow scenarios, and rain and snow scenarios. Through correlation analysis, the primary meteorological factors were identified which were subsequently utilized as inputs alongside historical power generation data. In the sub-model dedicated to rain and snow scenarios, variables such as rainfall and snowfall amounts were incorporated as additional input parameters. The hourly photovoltaic power generation output was served as the model’s output. The results indicated that the proposed model effectively ensured accurate forecasts. During no-rain and no-snow weather conditions, the prediction error metrics showcased superior performance: the mean absolute percentage error (MAPE) consistently remained below 13%, meeting the stringent requirement of the power grid’s tolerance level below 20%. Moreover, the normalized root mean square error (NRMSE) ranged between 6% and 9%, while the coefficient of determination (R²) exceeded 0.9. These underscored the remarkable prediction accuracy achieved by the model. Under rainy and snowy weather conditions, although MAPE slightly increased to the range of 14% to 20% compared to that of scenarios without rain and snow, it still adhered to the stringent requirement. NRMSE varied between 4.5% and 8%, and R² remained consistently above 0.9, indicative of satisfactory model performance even in adverse weather conditions. The successful application of the proposed model in predicting hourly photovoltaic power generation output during winter in Henan Province bears significant practical implications for the advancement and integration of renewable energy technologies. Full article

(This article belongs to the Topic Sustainable Energy Technology, 2nd Edition)

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15 pages, 2416 KiB

Open AccessArticle

Prospective Life Cycle Assessment of Biological Methanation in a Trickle-Bed Pilot Plant and a Potential Scale-Up

by Michael Heberl, Christian Withelm, Anja Kaul, Daniel Rank and Michael Sterner

Energies 2024, 17(9), 2206; https://doi.org/10.3390/en17092206 - 3 May 2024

Viewed by 1200

Abstract

The fluctuating nature of renewable energies results in the need for sustainable storage technologies to defossilize the energy system without other negative consequences for humans and the environment. In this study, a pilot-scale trickle-bed reactor for biological methanation and various scale-up scenarios for [...] Read more.

The fluctuating nature of renewable energies results in the need for sustainable storage technologies to defossilize the energy system without other negative consequences for humans and the environment. In this study, a pilot-scale trickle-bed reactor for biological methanation and various scale-up scenarios for 2024 and 2050 were investigated using life cycle assessment. A best- and worst-case scenario for technology development until 2050 was evolved using cross-consistency analysis and a morphological field, based on which the data for the ecological models were determined. The results show that the plant scale-up has a very positive effect on the ecological consequences of methanation. In the best-case scenario, the values are a factor of 23–780 lower than those of the actual plant today. A hot-spot analysis showed that electrolysis operation has an especially large impact on total emissions. The final Monte Carlo simulation shows that the technology is likely to achieve a low global warming potential with a median of 104.0 kg CO₂-eq/MWh CH₄ and thus can contribute to decarbonization. Full article

(This article belongs to the Topic Sustainable Energy Technology, 2nd Edition)

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27 pages, 44288 KiB

Open AccessFeature PaperReview

State of the Art of Renewable Sources Potentialities in the Middle East: A Case Study in the Kingdom of Saudi Arabia

by Gianfranco Di Lorenzo, Erika Stracqualursi, Giovanni Vescio and Rodolfo Araneo

Energies 2024, 17(8), 1816; https://doi.org/10.3390/en17081816 - 10 Apr 2024

Cited by 3 | Viewed by 1754

Abstract

The Kingdom of Saudi Arabia is experiencing a surge in electricity demand, with power generation increasing 4 times in 25 years from 1990 to 2014. Despite the abundant primary renewable energy sources, the country has overlooked them in the past in national energy [...] Read more.

The Kingdom of Saudi Arabia is experiencing a surge in electricity demand, with power generation increasing 4 times in 25 years from 1990 to 2014. Despite the abundant primary renewable energy sources, the country has overlooked them in the past in national energy policies. However, in recent years, renewable energy has become a part of the Kingdom of Saudi Arabia’s energy conservation policy due to climate changes, technological progress, economies of scale, and increased competitiveness in supply chains. The Saudi government has created the King Abdullah City for Atomic and Renewable Energy (KACARE) to develop national strategies for effectively utilizing renewable and nuclear energy. This paper reviews the current state of the art of the renewable energy technologies available on the market and evaluates the installation of renewable energy plants near Saudi Arabia’s East Coast for a new town, focusing on technical rather than economic aspects. The paper provides a wide review of the possible technical solutions to exploit the producibility of different renewable sources, considering the challenging climate conditions typical of desert areas. The analysis of a real case study shows a high availability of wind and solar irradiance that allow a net energy production of 354 and 129 GWh, respectively. In addition, the comparison between a typical ground-mounted photovoltaic (PV) system and an emerging floating PV reveals that for the same installed power, occupied area, and environmental conditions, the latter has a 4% greater performance ratio due to the cooling effect of water. Full article

(This article belongs to the Topic Sustainable Energy Technology, 2nd Edition)

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17 pages, 29537 KiB

Open AccessArticle

Enhanced Model Predictive Control for Induction Motor Drives in Marine Electric Power Propulsion System

by Tongzhen Liu, Xuliang Yao and Jiabao Kou

J. Mar. Sci. Eng. 2024, 12(3), 378; https://doi.org/10.3390/jmse12030378 - 22 Feb 2024

Cited by 1 | Viewed by 1272

Abstract

Marine electric propulsion is an important topic in the research of modern ships and underwater vehicles. The propulsion motor drives based on model predictive control (MPC) are becoming increasingly popular in marine propulsion systems as an emerging technology. However, the multi-objective optimization in [...] Read more.

Marine electric propulsion is an important topic in the research of modern ships and underwater vehicles. The propulsion motor drives based on model predictive control (MPC) are becoming increasingly popular in marine propulsion systems as an emerging technology. However, the multi-objective optimization in conventional MPC requires cumbersome weighting factor tuning. The relatively large computational cost is also detrimental to the industrial application of MPC. Aiming at reducing the computational complexity of multi-objective optimization without weighting factors, this paper proposes an enhanced ranking-based MPC method for induction motor drives in marine electric power propulsion. The presented control set pre-optimization aims to reduce the computational complexity of enumeration and ranking. Based on the sign of torque prediction deviation, the proposed method avoids enumerating all fundamental voltage vectors. Consequently, the number of candidate elements in the initial control set are reduced to four without excessively excluding feasible solutions. By converting predicted numerical errors into ranking results, the proposed MPC seeks the optimal solution among the candidates through improved ranking evaluation. Considering the situation of simultaneous optimal ranking, the normalization error judgment is developed to further optimize the optimal solution selection process. The simulation and experimental results confirm that the proposed MPC is simple and effective. Without the involvement of tuning the weighting factors, the proposed method achieves good performance. Full article

(This article belongs to the Topic Sustainable Energy Technology, 2nd Edition)

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22 pages, 7782 KiB

Open AccessArticle

Hydrodynamic Simulation of Green Hydrogen Catamaran Operating in Lisbon, Portugal

by Gaurav Soni, Rui Costa Neto and Lúcia Moreira

J. Mar. Sci. Eng. 2023, 11(12), 2273; https://doi.org/10.3390/jmse11122273 - 30 Nov 2023

Cited by 3 | Viewed by 1785

Abstract

Similar to other industries, the maritime industry is also facing increasing restrictions on ships regarding pollution control. The research presented in this paper is aimed at studying the pros and cons of alternative fuels followed by a detailed analysis on hydrogen fuel cells [...] Read more.

Similar to other industries, the maritime industry is also facing increasing restrictions on ships regarding pollution control. The research presented in this paper is aimed at studying the pros and cons of alternative fuels followed by a detailed analysis on hydrogen fuel cells (PEMFC) for a particular ship operating in Lisbon, Portugal. Dynamic forces acting on the ship have been studied for a year. Assessing various scenarios based on these results aids ship operators in making informed decisions regarding the future course of action for their existing vessels. These different cases are first: business as usual (diesel engine), second: replacing the diesel engine with a hydrogen hybrid system and, third: replacement of the ship with a new hydrogen hybrid ship. The study is based on the simulation of numerical equations and CFD simulation results. As the result, the second scenario is best suited in both aspects; namely, environmental and economic. Full article

(This article belongs to the Topic Sustainable Energy Technology, 2nd Edition)

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17 pages, 5821 KiB

Open AccessArticle

Full Operating Range Optimization Design Method of LLC Resonant Converter in Marine DC Power Supply System

by Xiao Han, Xuliang Yao and Yuefeng Liao

J. Mar. Sci. Eng. 2023, 11(11), 2142; https://doi.org/10.3390/jmse11112142 - 9 Nov 2023

Cited by 5 | Viewed by 1438

Abstract

The marine DC power supply system is the key to a ship’s power supply, which needs to convert the energy from storage batteries or distributed power generation units into stable DC voltage for electric propulsion or the ship’s electronics. The LLC resonant converter [...] Read more.

The marine DC power supply system is the key to a ship’s power supply, which needs to convert the energy from storage batteries or distributed power generation units into stable DC voltage for electric propulsion or the ship’s electronics. The LLC resonant converter can be used as the key power conversion link in the marine DC power supply system due to its ability to realize electrical isolation in a high-power environment and soft switching within a wide load range. Aiming at the problem of sudden changes in voltage gain at a high switching frequency under light load conditions and the problem of insufficient voltage gain under heavy load conditions due to the parasitic parameters of power devices (mainly referring to the junction capacitor), this paper first proposes a full operating range performance optimization design method. By adding an auxiliary circuit that can be opened according to the operating conditions and a multi-objective particle swarm parameter optimization method that considers the converter loss and voltage gain under heavy load conditions, the performance of the LLC resonant converter can be improved in a full range of operating conditions. Finally, the effectiveness of the proposed method is verified by an experimental prototype and compared with the conventional methods and existing solutions to highlight the superiority of the proposed method in this paper. Full article

(This article belongs to the Topic Sustainable Energy Technology, 2nd Edition)

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18 pages, 11719 KiB

Open AccessArticle

Global Atlas of Marine Floating Solar PV Potential

by David Firnando Silalahi and Andrew Blakers

Solar 2023, 3(3), 416-433; https://doi.org/10.3390/solar3030023 - 27 Jul 2023

Cited by 14 | Viewed by 16972

Abstract

In this paper, we analyse 40 years of maximum wind speed and wave height data to identify potential sites for solar photovoltaic (PV) systems floating on seas and oceans. Maximum hourly wave height and wind speed data were segregated into 5 distinct categories. [...] Read more.

In this paper, we analyse 40 years of maximum wind speed and wave height data to identify potential sites for solar photovoltaic (PV) systems floating on seas and oceans. Maximum hourly wave height and wind speed data were segregated into 5 distinct categories. These categorisations were then combined at the nearest wind speed and wave height grid point for each sea location, generating a comprehensive wind–wave map via a geographic information system (GIS) visualisation. We find that regions around the equator are generally calm, i.e., free from strong winds and large waves. The most favourable locations are around the Indonesian archipelago, and the Gulf of Guinea on the west coast of tropical Africa. Our analysis indicates the huge potential of floating solar PV systems in calm tropical maritime regions, capable of generating about one million terawatt-hours per year in regions that rarely experience waves larger than 6 m or winds stronger than 15 m/s. This study furthers our understanding of alternative renewable energy options, emphasising the promising potential of offshore floating solar PV systems in the global energy transition. Full article

(This article belongs to the Topic Sustainable Energy Technology, 2nd Edition)

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14 pages, 4818 KiB

Open AccessArticle

Optimization of Flow Channel Design with Porous Medium Layers in a Proton Exchange Membrane Electrolyzer Cell

by Wei-Hsin Chen, Yaun-Sheng Wang, Min-Hsing Chang, Liwen Jin, Lip Huat Saw, Chih-Chia Lin and Ching-Ying Huang

Energies 2023, 16(15), 5642; https://doi.org/10.3390/en16155642 - 27 Jul 2023

Viewed by 1979

Abstract

This study aims to optimize the flow channel design for a proton exchange membrane electrolyzer cell (PEMEC) to minimize the pressure drop across the cell. The pattern of parallel flow channels is considered with a dual-porous layer structure sandwiched between the flow channel [...] Read more.

This study aims to optimize the flow channel design for a proton exchange membrane electrolyzer cell (PEMEC) to minimize the pressure drop across the cell. The pattern of parallel flow channels is considered with a dual-porous layer structure sandwiched between the flow channel plate and the catalyst layer. Four geometric factors are considered in the optimization analysis, including the width of the flow channel, the depth of the flow channel, the particle diameter of the large-pore porous layer, and the particle diameter of the small-pore porous layer. Computational fluid dynamics (CFD) is used to simulate the flow field, and based on the results of the CFD simulation, the Taguchi method is employed to analyze the optimal flow channel design. The importance of the factors is further analyzed by the analysis of variance (ANOVA) method. Three inlet velocities are assigned in the Taguchi analysis, which are 0.01, 0.1332, and 0.532 m/s, and then an orthogonal array is constructed and analyzed for each inlet flow condition. It is found that the optimal combination of the factors is the depth of the flow channel 1 mm, the width of the flow channel 3 mm, the particle diameter of the large-pore porous layer 0.212 mm, and the particle diameter of the small-pore porous layer 0.002 mm. The pressure drop across the PEMEC is minimized at the condition with the optimal combination of the factors. The ANOVA analysis shows that the depth of the flow channel exhibits the most significant impact on the pressure drop, while the other factors play minor roles only. Full article

(This article belongs to the Topic Sustainable Energy Technology, 2nd Edition)

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27 pages, 11193 KiB

Open AccessArticle

Effects of Boundary Conditions on Performance Prediction of Deep-Buried Ground Heat Exchangers for Geothermal Energy Utilization

by Zhendi Ma, Siyu Qin, Yuping Zhang, Wei-Hsin Chen, Guosheng Jia, Chonghua Cheng and Liwen Jin

Energies 2023, 16(13), 4874; https://doi.org/10.3390/en16134874 - 22 Jun 2023

Cited by 1 | Viewed by 1389

Abstract

An accurate prediction for deep-buried ground heat exchangers (DBGHEs) is the premise for efficient utilization of geothermal energy. Due to the complexity of the geological composition spanning thousands of meters, the configuration of boundary conditions plays a critical role in evaluating DBGHE thermal [...] Read more.

An accurate prediction for deep-buried ground heat exchangers (DBGHEs) is the premise for efficient utilization of geothermal energy. Due to the complexity of the geological composition spanning thousands of meters, the configuration of boundary conditions plays a critical role in evaluating DBGHE thermal performance. This paper proposed a three-dimensional model of full-scale DBGHE involving both conductive and convective heat transfer in aquifuge and aquifer layers. The constant inlet temperature and constant heating power boundaries in the DBGHE domain, and the surface–bottom temperature and heat flux boundaries in the rock-soil domain were examined. It was found that the differences in the performance prediction caused by different DBGHE boundary conditions were closely related to the system’s operating time. The relative differences in heat extraction amount and average borehole temperature of 2000 m DBGHE caused by the two inlet boundaries on the 30th day were, respectively, 19.5% and 18.3%, while these differences on the 120th day were decreased to 8.4% and 9.9%, respectively. It was found that the constant inlet temperature boundary was more appropriate than the constant heating power condition for estimating aquifer effects on the performance of DBGHE. For the rock-soil domain, the results showed that the heat extraction amount of DBGHE under the heat flux boundary was 12.6%–13.6% higher than that under the surface–bottom temperature boundary. Particularly, when considering the velocity change of groundwater in the aquifer, the relative difference in heat extraction amount increments caused by the two types of rock-soil boundaries can reach 26.6% on the 120th day. It was also found that the thermal influence radius at the end of a heating season was hardly affected by either the DBGHE inlet or rock-soil domain boundary conditions. Full article

(This article belongs to the Topic Sustainable Energy Technology, 2nd Edition)

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30 pages, 3245 KiB

Open AccessReview

State-of-the-Art Review of Small Modular Reactors

by Carlo L. Vinoya, Aristotle T. Ubando, Alvin B. Culaba and Wei-Hsin Chen

Energies 2023, 16(7), 3224; https://doi.org/10.3390/en16073224 - 3 Apr 2023

Cited by 14 | Viewed by 10099

Abstract

The decarbonization of the energy industry is one of the key pillars in the reduction of greenhouse gas emissions in the atmosphere. The energy generation industry is an important driver in the development of nations. Small modular reactors (SMRs) are considered an affordable [...] Read more.

The decarbonization of the energy industry is one of the key pillars in the reduction of greenhouse gas emissions in the atmosphere. The energy generation industry is an important driver in the development of nations. Small modular reactors (SMRs) are considered an affordable energy generation technology that can provide clean energy that is comparable to other renewable energy technologies. However, several critical issues are established in the full adoption of and investment in SMRs in developing nations. A state-of-the-art review of the SMRs is proposed, involving key issues on technological, economic, environmental, and socio-political aspects. Methods of aggregating these factors in order to determine a country’s suitability to invest in SMRs have been explored, while also determining specific areas needing improvement. Full article

(This article belongs to the Topic Sustainable Energy Technology, 2nd Edition)

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23 pages, 9816 KiB

Open AccessArticle

Research on a DC–DC Converter and Its Advanced Control Strategy Applied to the Integrated Energy System of Marine Breeding Platforms

by Hongxing Chen, Weiming Lin and Wei He

J. Mar. Sci. Eng. 2023, 11(3), 512; https://doi.org/10.3390/jmse11030512 - 27 Feb 2023

Cited by 1 | Viewed by 1625

Abstract

The deep-sea aquaculture industry will become one of the important pillars of the future marine economy. However, the application of clean energy in the new scenario needs to be strengthened for platform operation. For this kind of renewable-energy distributed-generation system, an energy storage [...] Read more.

The deep-sea aquaculture industry will become one of the important pillars of the future marine economy. However, the application of clean energy in the new scenario needs to be strengthened for platform operation. For this kind of renewable-energy distributed-generation system, an energy storage system is essential. A bidirectional DC–DC converter is essential for distributed power generation systems. It connects a variety of renewable energy sources with energy storage cells. A high-gain bidirectional Cuk circuit with zero ripple is proposed in the paper. It is characterized by a simple structure, zero ripple, low voltage stress of semiconductor power devices, and high voltage gain. A passivity-based control with linear active disturbance rejection is proposed to solve the problems of the large steady-state error. The zero steady-state error, strong robustness, and whole-range stability have been obtained for the proposed control strategy. Finally, a simulation was carried out. A 100 W, 48 V/400 V prototype was built to verify the validity of the theoretical analysis for the proposed circuit. The improved passivity-based control strategy was verified to solve the contradiction between rapidity and overshoot. It can be realized to improve the dynamic performance of the proposed converter and achieve robust control. Full article

(This article belongs to the Topic Sustainable Energy Technology, 2nd Edition)

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16 pages, 2159 KiB

Open AccessArticle

Performance of a Wet Electrostatic Precipitator in Marine Applications

by Anssi Järvinen, Kati Lehtoranta, Päivi Aakko-Saksa, Mikko Karppanen, Timo Murtonen, Jarno Martikainen, Jarmo Kuusisto, Sami Nyyssönen, Päivi Koponen, Pekka Piimäkorpi, Eero Friman, Varpu Orasuo, Jaakko Rintanen, Juha Jokiluoma, Niina Kuittinen and Topi Rönkkö

J. Mar. Sci. Eng. 2023, 11(2), 393; https://doi.org/10.3390/jmse11020393 - 10 Feb 2023

Cited by 9 | Viewed by 2611

Abstract

Emissions of marine traffic can be lowered by switching to less polluting fuels or by investing in exhaust aftertreatment. Electrostatic precipitation is a widely used method for particle removal but it is not currently used in combination with marine engines. This study presents [...] Read more.

Emissions of marine traffic can be lowered by switching to less polluting fuels or by investing in exhaust aftertreatment. Electrostatic precipitation is a widely used method for particle removal but it is not currently used in combination with marine engines. This study presents the particle filtration characteristics of an emission reduction system designed for marine applications and consisting of a scrubber and a Wet Electrostatic Precipitator (WESP) in series. Partial flow of exhaust from a 1.6 MW marine engine, operated with light and heavy fuel oil, was led to the system. Particle concentrations were measured before the system, after the scrubber and after the WESP. Particle removal characteristics were determined for different engine loads. The scrubber alone removed 15–55% of non-volatile particle number, 30–40% of particle mass and 30–40% of black carbon mass depending on engine load, when HFO fuel was used. By studying particle size distributions, scrubber was found also to generate particles seen as an additional mode in 20–40 nm size range. The system combining the scrubber and WESP removed over 98.5% of particles in number, mass and black carbon metrics when HFO fuel was used. With MDO fuel, 96.5% of PN and 99% of black carbon were removed. Full article

(This article belongs to the Topic Sustainable Energy Technology, 2nd Edition)

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24 pages, 4466 KiB

Open AccessArticle

Performance Characteristic Analysis of Metallic and Non-Metallic Oxide Nanofluids for a Compound Parabolic Collector: Improvement of Renewable Energy Technologies in Buildings

by Muhammad Kaleem, Muzaffar Ali, Nadeem Ahmed Sheikh, Javed Akhtar, Rasikh Tariq and Jaroslaw Krzywanski

Energies 2023, 16(3), 1298; https://doi.org/10.3390/en16031298 - 26 Jan 2023

Cited by 3 | Viewed by 1974

Abstract

The building sector is targeting net-zero emissions through the integration of renewable energy technologies, especially for space cooling and heating applications. In this regard, the use of solar thermal concentrating collectors is of vital importance. The performance of these collectors increases by using [...] Read more.

The building sector is targeting net-zero emissions through the integration of renewable energy technologies, especially for space cooling and heating applications. In this regard, the use of solar thermal concentrating collectors is of vital importance. The performance of these collectors increases by using an efficient fluid such as a nanofluid due to their high thermal conductivity. This research addresses the preparation, stability analysis, and characterisation of metallic and non-metallic oxide nanofluids and their experimental analysis in a compound parabolic collector (CPC) system. Five different combinations of nanofluids are used with different volumetric concentrations (0.025%, 0.05%, and 0.075%) including multi-wall carbon nanotube with water (MWCNT–H₂O), multi-wall carbon nanotube with ethylene glycol (MWCNT–EG), aluminium oxide with water (Al₂O₃–H₂O), aluminium oxide with ethylene glycol (Al₂O₃–EG), and magnesium oxide with ethylene glycol (MgO–EG). The prepared nanofluids are characterised in terms of thermal conductivity and viscosity. Detailed experimentation is performed to investigate the CPC system integrated with the nanofluids. The results obtained from the detailed characterisation of the MWCNT–H₂O nanofluid showed that the nanofluids have a 37.17% better thermal conductivity than distilled water as a primary fluid, and the MWCNT–EG nanofluid has demonstrated an increase in viscosity by 8.5% compared to ethylene glycol (EG). The experimental analysis revealed that the thermal efficiency of the collector integrated with the MWCNT–H₂O nanofluid is increased by 33% compared to water. Meanwhile, the thermal efficiency of the collector with MWCNT–EG was increased by 24.9% compared to EG. Moreover, a comparative analysis among metallic nanofluids was also performed, i.e., Al₂O₃–H₂O, Al₂O₃–EG, and MgO–EG. In each case, the thermal efficiency of the collector was recorded, which was greater than the base fluid by percentages of 29.4%, 22.29%, and 23.1%, respectively. The efficiency of non-metallic nanofluids is better than metallic nanofluids by 7.7%. From the obtained results, it can be concluded that the CPC system performed best with MWCNT–H₂O compared to any other combination of nanofluids. Full article

(This article belongs to the Topic Sustainable Energy Technology, 2nd Edition)

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14 pages, 1909 KiB

Open AccessArticle

Objective Functions and Performance Optimization of Ocean Thermal Energy Conversion (OTEC) with CO₂-Based Binary Zeotropic Mixture Power Cycle

by Weixiu Shi, Yin Sun, Lisheng Pan, Linjian Song and Xiaolin Wei

J. Mar. Sci. Eng. 2023, 11(1), 140; https://doi.org/10.3390/jmse11010140 - 7 Jan 2023

Viewed by 2157

Abstract

Ocean thermal energy is a huge renewable and clean energy. For different applications of the Ocean Thermal Energy Conversion (OTEC) system, new objective functions are proposed and optimal CO₂-based binary zeotropic mixtures for each objective function are discussed. Propane, butane, isobutane, [...] Read more.

Ocean thermal energy is a huge renewable and clean energy. For different applications of the Ocean Thermal Energy Conversion (OTEC) system, new objective functions are proposed and optimal CO₂-based binary zeotropic mixtures for each objective function are discussed. Propane, butane, isobutane, and pentane were selected as the secondary component of the mixture working fluid. Based on each objective function, some parameters of the CO₂-based binary zeotropic mixture power cycle were studied and the optimal working fluids were obtained. The results indicated that the thermal efficiency showed an upwards trend as the evaporating temperature increased from 20 to 23 °C and decreased as the molar fraction of the secondary component of the working fluid increased from 0.01 to 0.05, but the specific volumetric flow showed the opposite trend. The specific net power increased as the evaporating temperature increased, and the net power output had a greater effect on the variations in the specific net power than the molar fraction of the secondary component. When taking thermal efficiency or specific volumetric flow as the objective functions, CO₂/propane was the suitable working fluid under the considered conditions; in the case that specific net power was taken as the objective function, CO₂/butane (0.97/0.03 or 0.96/0.04 molar ratio) or CO₂/isobutane (0.97/0.03, 0.96/0.04, or 0.95/0.05 molar ratio) were suitable under the considered evaporating temperature. Full article

(This article belongs to the Topic Sustainable Energy Technology, 2nd Edition)

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