K. Mathioudakis, A. Alexiou, N. Aretakis, C. Romesis
A review of existing research on signatures of gas turbine faults is presented. Faults that influence the aerothermodynamic performance of compressors and turbines, such as fouling, tip clearance increase, erosion, variable geometry system malfunction, and object impact damage, are covered. The signatures of such faults, which are necessary for establishing efficient gas path diagnostic methods, are studied. They are expressed through mass flow capacity and efficiency deviations. The key characteristics of the ratio of such deviations are investigated in terms of knowledge existing in published research. Research based on experimental studies, field data, and results of detailed fluid dynamic computations that exist today is found to provide such information. It is shown that although such signatures may be believed to have a unique correspondence to the type of component fault, this is only true when a particular engine and fault type are considered. The choice of diagnostic methods by developers should, thus, be guided by such considerations instead of using values taken from the literature without considering the features of the problem at hand.
{"title":"Signatures of Compressor and Turbine Faults in Gas Turbine Performance Diagnostics: A Review","authors":"K. Mathioudakis, A. Alexiou, N. Aretakis, C. Romesis","doi":"10.3390/en17143409","DOIUrl":"https://doi.org/10.3390/en17143409","url":null,"abstract":"A review of existing research on signatures of gas turbine faults is presented. Faults that influence the aerothermodynamic performance of compressors and turbines, such as fouling, tip clearance increase, erosion, variable geometry system malfunction, and object impact damage, are covered. The signatures of such faults, which are necessary for establishing efficient gas path diagnostic methods, are studied. They are expressed through mass flow capacity and efficiency deviations. The key characteristics of the ratio of such deviations are investigated in terms of knowledge existing in published research. Research based on experimental studies, field data, and results of detailed fluid dynamic computations that exist today is found to provide such information. It is shown that although such signatures may be believed to have a unique correspondence to the type of component fault, this is only true when a particular engine and fault type are considered. The choice of diagnostic methods by developers should, thus, be guided by such considerations instead of using values taken from the literature without considering the features of the problem at hand.","PeriodicalId":504870,"journal":{"name":"Energies","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141657363","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
With the requirement of energy decarbonization, natural gas (NG) and hydrogen (H2) become increasingly important in the world’s energy landscape. The liquefaction of NG and H2 significantly increases energy density, facilitating large-scale storage and long-distance transport. However, conventional liquefaction processes mainly adopt electricity-driven compression refrigeration technology, which generally results in high energy consumption and carbon dioxide emissions. Absorption refrigeration technology (ART) presents a promising avenue for enhancing energy efficiency and reducing emissions in both NG and H2 liquefaction processes. Its ability to utilize industrial waste heat and renewable thermal energy sources over a large temperature range makes it particularly attractive for sustainable energy practices. This review comprehensively analyzes the progress of ART in terms of working pairs, cycle configurations, and heat and mass transfer in main components. To operate under different driven heat sources and refrigeration temperatures, working pairs exhibit a diversified development trend. The environment-friendly and high-efficiency working pairs, in which ionic liquids and deep eutectic solvents are new absorbents, exhibit promising development potential. Through the coupling of heat and mass transfer within the cycle or the addition of sub-components, cycle configurations with higher energy efficiency and a wider range of operational conditions are greatly focused. Additives, ultrasonic oscillations, and mechanical treatment of heat exchanger surfaces efficiently enhance heat and mass transfer in the absorbers and generators of ART. Notably, nanoparticle additives and ultrasonic oscillations demonstrate a synergistic enhancement effect, which could significantly improve the energy efficiency of ART. For the conventional NG and H2 liquefaction processes, the energy-saving and carbon emission reduction potential of ART is analyzed from the perspectives of specific power consumption (SPC) and carbon dioxide emissions (CEs). The results show that ART integrated into the liquefaction processes could reduce the SPC and CE by 10~38% and 10~36% for NG liquefaction processes, and 2~24% and 5~24% for H2 liquefaction processes. ART, which can achieve lower precooling temperatures and higher energy efficiency, shows more attractive perspectives in low carbon emissions of NG and H2 liquefaction.
随着能源去碳化的要求，天然气（NG）和氢气（H2）在世界能源格局中变得越来越重要。天然气和氢气的液化可显著提高能量密度，便于大规模储存和远距离运输。然而，传统液化工艺主要采用电力驱动的压缩制冷技术，能耗和二氧化碳排放量普遍较高。吸收式制冷技术（ART）为提高 NG 和 H2 液化工艺的能效和减少排放提供了一条前景广阔的途径。它能够在较大的温度范围内利用工业废热和可再生热能，因此对可持续能源实践特别有吸引力。本综述全面分析了 ART 在工作对、循环配置以及主要部件的传热和传质方面的进展。为了在不同的驱动热源和制冷温度下运行，工作对呈现出多样化的发展趋势。以离子液体和深共晶溶剂为新型吸收剂的环保型高效工作对具有广阔的发展前景。通过在循环内耦合传热和传质或添加子组件，能效更高和运行条件范围更广的循环配置受到极大关注。添加剂、超声波振荡和热交换器表面的机械处理可有效增强 ART 吸收器和发生器的传热和传质。值得注意的是，纳米颗粒添加剂和超声波振荡具有协同增效作用，可显著提高 ART 的能效。针对传统的 NG 和 H2 液化工艺，从比能耗（SPC）和二氧化碳排放量（CEs）的角度分析了 ART 的节能和碳减排潜力。结果表明，将 ART 集成到液化工艺中，可使 NG 液化工艺的 SPC 和 CE 分别降低 10%~38% 和 10%~36%，H2 液化工艺的 SPC 和 CE 分别降低 2%~24% 和 5%~24%。ART 可实现更低的预冷温度和更高的能效，在天然气和 H2 液化的低碳排放方面具有更诱人的前景。
{"title":"Review on Absorption Refrigeration Technology and Its Potential in Energy-Saving and Carbon Emission Reduction in Natural Gas and Hydrogen Liquefaction","authors":"Lisong Wang, Lijuan He, Yijian He","doi":"10.3390/en17143427","DOIUrl":"https://doi.org/10.3390/en17143427","url":null,"abstract":"With the requirement of energy decarbonization, natural gas (NG) and hydrogen (H2) become increasingly important in the world’s energy landscape. The liquefaction of NG and H2 significantly increases energy density, facilitating large-scale storage and long-distance transport. However, conventional liquefaction processes mainly adopt electricity-driven compression refrigeration technology, which generally results in high energy consumption and carbon dioxide emissions. Absorption refrigeration technology (ART) presents a promising avenue for enhancing energy efficiency and reducing emissions in both NG and H2 liquefaction processes. Its ability to utilize industrial waste heat and renewable thermal energy sources over a large temperature range makes it particularly attractive for sustainable energy practices. This review comprehensively analyzes the progress of ART in terms of working pairs, cycle configurations, and heat and mass transfer in main components. To operate under different driven heat sources and refrigeration temperatures, working pairs exhibit a diversified development trend. The environment-friendly and high-efficiency working pairs, in which ionic liquids and deep eutectic solvents are new absorbents, exhibit promising development potential. Through the coupling of heat and mass transfer within the cycle or the addition of sub-components, cycle configurations with higher energy efficiency and a wider range of operational conditions are greatly focused. Additives, ultrasonic oscillations, and mechanical treatment of heat exchanger surfaces efficiently enhance heat and mass transfer in the absorbers and generators of ART. Notably, nanoparticle additives and ultrasonic oscillations demonstrate a synergistic enhancement effect, which could significantly improve the energy efficiency of ART. For the conventional NG and H2 liquefaction processes, the energy-saving and carbon emission reduction potential of ART is analyzed from the perspectives of specific power consumption (SPC) and carbon dioxide emissions (CEs). The results show that ART integrated into the liquefaction processes could reduce the SPC and CE by 10~38% and 10~36% for NG liquefaction processes, and 2~24% and 5~24% for H2 liquefaction processes. ART, which can achieve lower precooling temperatures and higher energy efficiency, shows more attractive perspectives in low carbon emissions of NG and H2 liquefaction.","PeriodicalId":504870,"journal":{"name":"Energies","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141658580","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Huaying Wang-Alho, K. Sirviö, C. Nuortila, Jonna Kaivosoja, Maciej Mikulski, Seppo Niemi
Methanol and hydrotreated vegetable oil (HVO) are complementary in the context of achieving ultra-low emission levels via low temperature combustion. HVO is a high-quality fuel fully compatible with compression ignition engines. Standalone methanol combustion is relatively straight-forward according to the Otto principle, with a spark ignited or in conventional dual-fuel (“liquid spark”) engines. These two fuels have by far the largest reactivity span amongst commercially available alternatives, allowing to secure controllable partially premixed compression ignition with methanol–HVO emulsification. This study investigates the corrosion of aluminum, carbon steel, stainless steel, and a special alloy of MoC210M/25CrMo4+SH, exposed to different combinations of HVO, HVO without additives (HVOr), methanol, and emulsion stabilizing additives (1-octanol or 1-dodecanol). General corrosive properties are well determined for all these surrogates individually, but their mutual interactions have not been researched in the context of relevant engine components. The experimental research involved immersion of metal samples into the fuels at room temperature for a duration of 60 days. The surfaces of the metals were inspected visually and the dissolution of the metals into fuels was evaluated by analyzing the fuels’ trace metal concentrations before and after the immersion test. Furthermore, this study compared the alterations in the chemical and physical properties of the fuels, such as density, kinematic viscosity, and distillation properties, due to possible corrosion products. Based on these results, methanol as 100% fuel or as blending component slightly increases the corrosion risk. Methanol had slight dissolving effect on aluminum (dissolving Al) and carbon steel (dissolving Zn). HVO, HVOr, and methanol–HVOr–co-solvents were compatible with the metals. No fuels induced visible corrosion on the metals’ surfaces. If corrosion products were formed in the fuel samples, they did not affect fuel parameters.
{"title":"Compatibility of Methanol-Hydrotreated Vegetable Oil Blends with Chosen Steels and Aluminum","authors":"Huaying Wang-Alho, K. Sirviö, C. Nuortila, Jonna Kaivosoja, Maciej Mikulski, Seppo Niemi","doi":"10.3390/en17143423","DOIUrl":"https://doi.org/10.3390/en17143423","url":null,"abstract":"Methanol and hydrotreated vegetable oil (HVO) are complementary in the context of achieving ultra-low emission levels via low temperature combustion. HVO is a high-quality fuel fully compatible with compression ignition engines. Standalone methanol combustion is relatively straight-forward according to the Otto principle, with a spark ignited or in conventional dual-fuel (“liquid spark”) engines. These two fuels have by far the largest reactivity span amongst commercially available alternatives, allowing to secure controllable partially premixed compression ignition with methanol–HVO emulsification. This study investigates the corrosion of aluminum, carbon steel, stainless steel, and a special alloy of MoC210M/25CrMo4+SH, exposed to different combinations of HVO, HVO without additives (HVOr), methanol, and emulsion stabilizing additives (1-octanol or 1-dodecanol). General corrosive properties are well determined for all these surrogates individually, but their mutual interactions have not been researched in the context of relevant engine components. The experimental research involved immersion of metal samples into the fuels at room temperature for a duration of 60 days. The surfaces of the metals were inspected visually and the dissolution of the metals into fuels was evaluated by analyzing the fuels’ trace metal concentrations before and after the immersion test. Furthermore, this study compared the alterations in the chemical and physical properties of the fuels, such as density, kinematic viscosity, and distillation properties, due to possible corrosion products. Based on these results, methanol as 100% fuel or as blending component slightly increases the corrosion risk. Methanol had slight dissolving effect on aluminum (dissolving Al) and carbon steel (dissolving Zn). HVO, HVOr, and methanol–HVOr–co-solvents were compatible with the metals. No fuels induced visible corrosion on the metals’ surfaces. If corrosion products were formed in the fuel samples, they did not affect fuel parameters.","PeriodicalId":504870,"journal":{"name":"Energies","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141656455","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The escalating energy demands in buildings, particularly for heating and cooling demands met by heat pumps, have placed a growing stress on energy resources. The bi-functional thermal diode tank (BTDT) is proposed as thermal energy storage to improve the heating and cooling performances of heat pumps in both summer and winter. The BTDT is an insulated water tank with a gravity heat pipe (GHP), which can harvest and store heat passively from sun radiation and the external environment during the daytime. In summer, it harvests and stores cold energy from the air and night sky during the daytime. The performance of the BTDT-assisted heat pump (BTDT-HP) system in Adelaide, Australia, during the 2021–2022 summer and winter seasons was evaluated by conducting a TRNSYS simulation. This study revealed that the BTDT-HP system outperformed the reference ASHP system, where up to 8% energy in heating and 39.75% energy in cooling could be saved. An overall reduction in the energy consumption of 18.89% was achieved. Increasing the BTDT volume and GHP panel area enabled the tank to store more thermal and cold energy across the winter and summer seasons, thereby improving the system’s performance. The maximum ESPs were found to be 31.6% and 41.2% for heating and cooling for the study case under optimal conditions. When the GHP panel area was fixed at 15 m2, the BTDT volume should be at least 28 m3 for the BTDT-HP system, boasting cooling and heating capacities of 40 kW and 43.2 kW, to achieve positive energy savings.
{"title":"TRNSYS Simulation of a Bi-Functional Solar-Thermal-Energy-Storage-Assisted Heat Pump System","authors":"Mingzhen Wang, Eric Hu, Lei Chen","doi":"10.3390/en17143376","DOIUrl":"https://doi.org/10.3390/en17143376","url":null,"abstract":"The escalating energy demands in buildings, particularly for heating and cooling demands met by heat pumps, have placed a growing stress on energy resources. The bi-functional thermal diode tank (BTDT) is proposed as thermal energy storage to improve the heating and cooling performances of heat pumps in both summer and winter. The BTDT is an insulated water tank with a gravity heat pipe (GHP), which can harvest and store heat passively from sun radiation and the external environment during the daytime. In summer, it harvests and stores cold energy from the air and night sky during the daytime. The performance of the BTDT-assisted heat pump (BTDT-HP) system in Adelaide, Australia, during the 2021–2022 summer and winter seasons was evaluated by conducting a TRNSYS simulation. This study revealed that the BTDT-HP system outperformed the reference ASHP system, where up to 8% energy in heating and 39.75% energy in cooling could be saved. An overall reduction in the energy consumption of 18.89% was achieved. Increasing the BTDT volume and GHP panel area enabled the tank to store more thermal and cold energy across the winter and summer seasons, thereby improving the system’s performance. The maximum ESPs were found to be 31.6% and 41.2% for heating and cooling for the study case under optimal conditions. When the GHP panel area was fixed at 15 m2, the BTDT volume should be at least 28 m3 for the BTDT-HP system, boasting cooling and heating capacities of 40 kW and 43.2 kW, to achieve positive energy savings.","PeriodicalId":504870,"journal":{"name":"Energies","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141662532","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Tomasz Surmacz, Bogdan Wierzbiński, W. Kuźniar, L. Witek
The sharing economy substitutes owning with accessing, promoting sustainable development by reducing excessive consumption and resource overuse, which harm the environment. Sharing reduces resource and energy use, lowering emissions and waste disposal costs, thus reducing environmental damage. This study identifies key factors that encourage Generation Z to embrace the sharing economy for goods and services, emphasizing its role in sustainable development. Conducted in May 2023, the study surveyed 442 Polish Generation Z individuals to examine their attitudes and behaviours regarding climate change. The research focused on this demographic due to their crucial role in addressing global issues. Data was collected using the CAWI method and analyzed with IBM SPSS and AMOS software through structural equation modelling (SEM). The analysis revealed three factors: Willingness to Share for Savings (WSS), Digital Customer Engagement (DCE), and Environmental Concern (EC). The results show that ecological concerns and digital engagement significantly influence people’s willingness to share, boosting environmental awareness and cost-saving behaviours. Generation Z’s sharing propensity and environmental consciousness are significantly shaped by digital engagement.
共享经济以获取取代拥有，通过减少过度消费和资源过度使用对环境造成的损害，促进可持续发展。共享减少了资源和能源的使用，降低了排放和废物处理成本，从而减少了对环境的破坏。本研究指出了鼓励 Z 世代接受商品和服务共享经济的关键因素，强调了共享经济在可持续发展中的作用。这项研究于 2023 年 5 月进行，对 442 名波兰 Z 世代进行了调查，研究他们对气候变化的态度和行为。由于Z世代在解决全球问题方面发挥着至关重要的作用，因此研究将重点放在了这一人群上。采用 CAWI 方法收集数据，并使用 IBM SPSS 和 AMOS 软件通过结构方程模型（SEM）进行分析。分析结果显示了三个因素：为节省开支而分享的意愿（WSS）、数字客户参与（DCE）和环境关注（EC）。结果显示，生态关注和数字参与显著影响了人们的分享意愿，促进了环保意识和成本节约行为。Z 世代的分享倾向和环保意识在很大程度上受数字参与的影响。
{"title":"Towards Sustainable Consumption: Generation Z’s Views on Ownership and Access in the Sharing Economy","authors":"Tomasz Surmacz, Bogdan Wierzbiński, W. Kuźniar, L. Witek","doi":"10.3390/en17143377","DOIUrl":"https://doi.org/10.3390/en17143377","url":null,"abstract":"The sharing economy substitutes owning with accessing, promoting sustainable development by reducing excessive consumption and resource overuse, which harm the environment. Sharing reduces resource and energy use, lowering emissions and waste disposal costs, thus reducing environmental damage. This study identifies key factors that encourage Generation Z to embrace the sharing economy for goods and services, emphasizing its role in sustainable development. Conducted in May 2023, the study surveyed 442 Polish Generation Z individuals to examine their attitudes and behaviours regarding climate change. The research focused on this demographic due to their crucial role in addressing global issues. Data was collected using the CAWI method and analyzed with IBM SPSS and AMOS software through structural equation modelling (SEM). The analysis revealed three factors: Willingness to Share for Savings (WSS), Digital Customer Engagement (DCE), and Environmental Concern (EC). The results show that ecological concerns and digital engagement significantly influence people’s willingness to share, boosting environmental awareness and cost-saving behaviours. Generation Z’s sharing propensity and environmental consciousness are significantly shaped by digital engagement.","PeriodicalId":504870,"journal":{"name":"Energies","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141662806","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
LVR-15 is a light-water-tank-type research reactor placed in a stainless-steel vessel under a shielding cover located in the Research Centre Rez (CVR) near Prague. It is operated at a steady-state power of up to 10 MWt under atmospheric pressure and is cooled by forced circulation. In 2011, the fuel was replaced, going from high-enriched uranium (HEU) to low-enriched uranium (LEU). After 2017, the State Office for Nuclear Safety (SUJB) asked CVR to evaluate the LVR-15 under Design Extended Conditions B (DEC-B). For this reason, a new model was developed in the MELCOR code, which allows for modelling the progression of a severe accident (SA) in light-water nuclear power plants and estimating the behaviour of the reactor under SA conditions. The model was built by collecting information about the LVR-15. Since the research reactor can have different core configurations according to the location of the core components, the core configuration with the most fuel (hottest campaign K221) was selected. Then, to create the radial nodalisation, the details of the core components were obtained and grouped in five radial rings and 27 axial levels. The simulation was run with the boundary conditions collected from campaign K221, and the results were compared with the reference values of the campaign with a negligible percentage of error. For the coolant inlet and outlet temperature, the reference values were 318.18 K and 323.5 K, respectively, while for the simulation, the steady state reached 319 K for the inlet temperature and 324 K for the outlet temperature. Additionally, the cladding temperature of the hottest assembly was compared with the reference value (353.72 K) and the steady-state simulation results (362 K). In future work, different transients leading to severe accidents will be simulated. When simulating the LVR-15 reactor with MELCOR, specific attention is required for the aluminium-cladded fuel assemblies, as the model requires some assumptions to cope with the phenomenological limitations.
{"title":"Development of a MELCOR Model for LVR-15 Severe Accidents Assessment","authors":"Alain Flores y Flores, G. Mazzini, A. Dambrosio","doi":"10.3390/en17143384","DOIUrl":"https://doi.org/10.3390/en17143384","url":null,"abstract":"LVR-15 is a light-water-tank-type research reactor placed in a stainless-steel vessel under a shielding cover located in the Research Centre Rez (CVR) near Prague. It is operated at a steady-state power of up to 10 MWt under atmospheric pressure and is cooled by forced circulation. In 2011, the fuel was replaced, going from high-enriched uranium (HEU) to low-enriched uranium (LEU). After 2017, the State Office for Nuclear Safety (SUJB) asked CVR to evaluate the LVR-15 under Design Extended Conditions B (DEC-B). For this reason, a new model was developed in the MELCOR code, which allows for modelling the progression of a severe accident (SA) in light-water nuclear power plants and estimating the behaviour of the reactor under SA conditions. The model was built by collecting information about the LVR-15. Since the research reactor can have different core configurations according to the location of the core components, the core configuration with the most fuel (hottest campaign K221) was selected. Then, to create the radial nodalisation, the details of the core components were obtained and grouped in five radial rings and 27 axial levels. The simulation was run with the boundary conditions collected from campaign K221, and the results were compared with the reference values of the campaign with a negligible percentage of error. For the coolant inlet and outlet temperature, the reference values were 318.18 K and 323.5 K, respectively, while for the simulation, the steady state reached 319 K for the inlet temperature and 324 K for the outlet temperature. Additionally, the cladding temperature of the hottest assembly was compared with the reference value (353.72 K) and the steady-state simulation results (362 K). In future work, different transients leading to severe accidents will be simulated. When simulating the LVR-15 reactor with MELCOR, specific attention is required for the aluminium-cladded fuel assemblies, as the model requires some assumptions to cope with the phenomenological limitations.","PeriodicalId":504870,"journal":{"name":"Energies","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141661793","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mohamed Nour El-Din, João Poças Martins, Nuno M. M. Ramos, Pedro F. Pereira
Energy performance-based contracts (EPCs) offer a promising solution for enhancing the energy performance of buildings, which is an overarching step towards achieving Net Zero Carbon Buildings, addressing climate change and improving occupants’ comfort. Despite their potential, their execution is constrained by difficulties that hinder their diffusion in the architecture, engineering, construction, and operation industry. Notably, the Measurement and Verification process is considered a significant impediment due to data sharing, storage, and security challenges. Nevertheless, there have been minimal efforts to analyze research conducted in this field systematically. A systematic analysis of 113 identified journal articles was conducted to fill this gap. A paucity of research tackling the utilization of digital technologies to enhance the implementation of EPCs was found. Consequently, this article proposes a framework integrating Digital Twin and Blockchain technologies to provide an enhanced EPC execution environment. Digital Twin technology leverages the system by monitoring and evaluating energy performance in real-time, predicting future performance, and facilitating informed decisions. Blockchain technology ensures the integrity, transparency, and accountability of information. Moreover, a private Blockchain infrastructure was originally introduced in the framework to eliminate high transaction costs related to on-chain storage and potential concerns regarding the confidentiality of information in open distributed ledgers.
{"title":"The Role of Blockchain-Secured Digital Twins in Promoting Smart Energy Performance-Based Contracts for Buildings","authors":"Mohamed Nour El-Din, João Poças Martins, Nuno M. M. Ramos, Pedro F. Pereira","doi":"10.3390/en17143392","DOIUrl":"https://doi.org/10.3390/en17143392","url":null,"abstract":"Energy performance-based contracts (EPCs) offer a promising solution for enhancing the energy performance of buildings, which is an overarching step towards achieving Net Zero Carbon Buildings, addressing climate change and improving occupants’ comfort. Despite their potential, their execution is constrained by difficulties that hinder their diffusion in the architecture, engineering, construction, and operation industry. Notably, the Measurement and Verification process is considered a significant impediment due to data sharing, storage, and security challenges. Nevertheless, there have been minimal efforts to analyze research conducted in this field systematically. A systematic analysis of 113 identified journal articles was conducted to fill this gap. A paucity of research tackling the utilization of digital technologies to enhance the implementation of EPCs was found. Consequently, this article proposes a framework integrating Digital Twin and Blockchain technologies to provide an enhanced EPC execution environment. Digital Twin technology leverages the system by monitoring and evaluating energy performance in real-time, predicting future performance, and facilitating informed decisions. Blockchain technology ensures the integrity, transparency, and accountability of information. Moreover, a private Blockchain infrastructure was originally introduced in the framework to eliminate high transaction costs related to on-chain storage and potential concerns regarding the confidentiality of information in open distributed ledgers.","PeriodicalId":504870,"journal":{"name":"Energies","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141661802","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
DC voltage is one of the important parameters of active power filters. Since the series hybrid active power filter does not withstand the fundamental voltage, it cannot absorb energy from the power grid, making it too difficult to control its DC voltage. In order to solve the DC voltage control problem, an improved control method for the series hybrid active power filter with magnetic flux compensation is proposed in this paper. In this improved method, the fundamental magnetic flux compensation coefficient is equal to 1, meeting the condition of fundamental magnetic flux compensation. This improved method does not rely on the precise detection and phase-locking of the fundamental voltage at the port of the series transformer. A phase-fixed active current component is generated directly by the inverter, enabling the active power filter (APF) to absorb active power from the power grid. Consequently, the active power absorbed by the APF from the power grid has a linear relationship with the active current component. Both simulation and experimentation verified the correctness and effectiveness of this proposed method.
{"title":"An Improved Control Method of DC Voltage for Series Hybrid Active Power Filter","authors":"Jianben Liu, Yuan Ni, Jun Zhao","doi":"10.3390/en17143390","DOIUrl":"https://doi.org/10.3390/en17143390","url":null,"abstract":"DC voltage is one of the important parameters of active power filters. Since the series hybrid active power filter does not withstand the fundamental voltage, it cannot absorb energy from the power grid, making it too difficult to control its DC voltage. In order to solve the DC voltage control problem, an improved control method for the series hybrid active power filter with magnetic flux compensation is proposed in this paper. In this improved method, the fundamental magnetic flux compensation coefficient is equal to 1, meeting the condition of fundamental magnetic flux compensation. This improved method does not rely on the precise detection and phase-locking of the fundamental voltage at the port of the series transformer. A phase-fixed active current component is generated directly by the inverter, enabling the active power filter (APF) to absorb active power from the power grid. Consequently, the active power absorbed by the APF from the power grid has a linear relationship with the active current component. Both simulation and experimentation verified the correctness and effectiveness of this proposed method.","PeriodicalId":504870,"journal":{"name":"Energies","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141662983","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The spatiotemporal evolution of the flow structures and coolant coverage of double-row film cooling with upstream forward jets and downstream backward jets, having a significant impact on film-cooling performance, is studied using the simplified thermal lattice Boltzmann method (STLBM). Moreover, the effect of the inclination angle of downstream backward jets is considered. The high-performance simulations of film cooling have been conducted by using our verified in-house solver. Results show that special flow structures, such as a sand dune-shaped protrusion, appear in double-row film cooling with upstream forward jets and downstream backward jets, which is mainly because of the blockage effect resulting from the coolant jet with backward injection. The interaction among structures results in the generation of an anti-counterrotating vortex pair (anti-CVP). The anti-CVP with the downwash motion can result in the attachment of coolant to the bottom wall, which promotes the stability and lateral coverage of coolant film. The momentum and heat transport are strengthened as the backward jet is injected into the boundary layer of the mainstream. Although the downstream evolution of the backward jet is not very smooth, its core attaches closely to the bottom wall due to the downwash motion of anti-CVP. Moreover, there is an obvious backflow zone shown in the trailing edge of the downstream backward jet with a large inclination angle. The obvious backflow makes the coolant attach to the bottom wall well. Therefore, the film cooling effectiveness is improved as the inclination angle of the downstream backward jet varies from αdown=135o to αdown=155o, with a constant blowing ratio of BR=0.5. In addition, the fluctuation of the bottom wall’s temperature is weak due to the stable coverage of the coolant layer under αdown=155o. The film-cooling performance with an inclination angle of αdown=155o is the best among all the cases studied in this work. This work provides essential insights into film cooling with backward coolant injection and contributes to obtaining a complete understanding of film cooling with backward coolant injection.
{"title":"The Evolution of Flow Structures and Coolant Coverage in Double-Row Film Cooling with Upstream Forward Jets and Downstream Backward Jets","authors":"Yanqin Shangguan, Fei-Long Cao","doi":"10.3390/en17143387","DOIUrl":"https://doi.org/10.3390/en17143387","url":null,"abstract":"The spatiotemporal evolution of the flow structures and coolant coverage of double-row film cooling with upstream forward jets and downstream backward jets, having a significant impact on film-cooling performance, is studied using the simplified thermal lattice Boltzmann method (STLBM). Moreover, the effect of the inclination angle of downstream backward jets is considered. The high-performance simulations of film cooling have been conducted by using our verified in-house solver. Results show that special flow structures, such as a sand dune-shaped protrusion, appear in double-row film cooling with upstream forward jets and downstream backward jets, which is mainly because of the blockage effect resulting from the coolant jet with backward injection. The interaction among structures results in the generation of an anti-counterrotating vortex pair (anti-CVP). The anti-CVP with the downwash motion can result in the attachment of coolant to the bottom wall, which promotes the stability and lateral coverage of coolant film. The momentum and heat transport are strengthened as the backward jet is injected into the boundary layer of the mainstream. Although the downstream evolution of the backward jet is not very smooth, its core attaches closely to the bottom wall due to the downwash motion of anti-CVP. Moreover, there is an obvious backflow zone shown in the trailing edge of the downstream backward jet with a large inclination angle. The obvious backflow makes the coolant attach to the bottom wall well. Therefore, the film cooling effectiveness is improved as the inclination angle of the downstream backward jet varies from αdown=135o to αdown=155o, with a constant blowing ratio of BR=0.5. In addition, the fluctuation of the bottom wall’s temperature is weak due to the stable coverage of the coolant layer under αdown=155o. The film-cooling performance with an inclination angle of αdown=155o is the best among all the cases studied in this work. This work provides essential insights into film cooling with backward coolant injection and contributes to obtaining a complete understanding of film cooling with backward coolant injection.","PeriodicalId":504870,"journal":{"name":"Energies","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141660496","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hongyi Zhang, Zhonghui Zhao, Jun Wu, Xinyan Wang, Weihao Ouyang, Zhaowen Wang
Methanol is a promising alternative fuel due to its wide availability of raw materials, mature production processes, and low production cost. However, because of the low cetane number, methanol must include a more reactive fuel to assist with combustion when used in compression ignition (CI) engines. In this study, based on the optical CI engine platform, methanol is injected into the intake port, and diesel is directly injected into the cylinder to achieve dual-fuel combustion. The effects of the methanol energy ratios and diesel split injection strategies on combustion are investigated. The results show that the premixed blue flame was mainly concentrated in the near wall region, whereas the yellow flame produced by diesel combustion tended to concentrate in the central region as the methanol energy ratio increased. When the methanol energy ratio exceeded 50%, the ignition delay was significantly prolonged, while the flame area was greatly reduced. Meanwhile, the peak values for the cylinder pressure and heat release rate decreased significantly, indicating a significant deterioration in combustion. At the earlier diesel pre-injection timing at −58°, the overall dual-fuel combustion at each main injection timing exhibited low-temperature premixed combustion characteristics, with a lower peak exothermic rate and flame brightness. At the later pre-injection timing at −33°, the spray flame at all main injection timings could be observed, with higher peak heat release rates and indications of thermal efficiency. Combustion at later main injection timings was characterized by diffusion combustion, and the main injection timing could effectively regulate the combustion process through phase adjustment.
甲醇原料来源广泛，生产工艺成熟，生产成本低，是一种很有前途的替代燃料。然而，由于十六烷值较低，甲醇在用于压燃式（CI）发动机时，必须使用活性更高的燃料来辅助燃烧。本研究以光学 CI 发动机平台为基础，将甲醇注入进气口，同时将柴油直接注入气缸，以实现双燃料燃烧。研究了甲醇能量比和柴油分注策略对燃烧的影响。结果表明，随着甲醇能量比的增加，预混的蓝色火焰主要集中在近壁区域，而柴油燃烧产生的黄色火焰则倾向于集中在中心区域。当甲醇能量比超过 50%时，点火延迟时间明显延长，火焰面积大大缩小。同时，气缸压力和放热率的峰值也明显下降，表明燃烧情况明显恶化。在较早的-58°柴油预喷射正时，各主喷射正时的双燃料燃烧总体上表现出低温预混燃烧的特征，放热率峰值和火焰亮度较低。在-33°的较晚预喷射定时下，可以观察到所有主喷射定时下的喷射火焰，峰值放热率较高，热效率较高。在较晚的主喷射定时下，燃烧以扩散燃烧为特征，主喷射定时可通过相位调节有效地调节燃烧过程。
{"title":"Investigation of Split Diesel Injections in Methanol/Diesel Dual-Fuel Combustion in an Optical Engine","authors":"Hongyi Zhang, Zhonghui Zhao, Jun Wu, Xinyan Wang, Weihao Ouyang, Zhaowen Wang","doi":"10.3390/en17143382","DOIUrl":"https://doi.org/10.3390/en17143382","url":null,"abstract":"Methanol is a promising alternative fuel due to its wide availability of raw materials, mature production processes, and low production cost. However, because of the low cetane number, methanol must include a more reactive fuel to assist with combustion when used in compression ignition (CI) engines. In this study, based on the optical CI engine platform, methanol is injected into the intake port, and diesel is directly injected into the cylinder to achieve dual-fuel combustion. The effects of the methanol energy ratios and diesel split injection strategies on combustion are investigated. The results show that the premixed blue flame was mainly concentrated in the near wall region, whereas the yellow flame produced by diesel combustion tended to concentrate in the central region as the methanol energy ratio increased. When the methanol energy ratio exceeded 50%, the ignition delay was significantly prolonged, while the flame area was greatly reduced. Meanwhile, the peak values for the cylinder pressure and heat release rate decreased significantly, indicating a significant deterioration in combustion. At the earlier diesel pre-injection timing at −58°, the overall dual-fuel combustion at each main injection timing exhibited low-temperature premixed combustion characteristics, with a lower peak exothermic rate and flame brightness. At the later pre-injection timing at −33°, the spray flame at all main injection timings could be observed, with higher peak heat release rates and indications of thermal efficiency. Combustion at later main injection timings was characterized by diffusion combustion, and the main injection timing could effectively regulate the combustion process through phase adjustment.","PeriodicalId":504870,"journal":{"name":"Energies","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141662111","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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