Luminescent coupling in a top-limited multi-junction solar cell was investigated by employing a 3D circuit model and semiconductor physics. The calculation methods for computing both electro-luminescent and photo-luminescent coupling efficiencies were introduced. Since the calculation processes were circuit independent, they can be applied directly to any form of an equivalent circuit model of a solar cell. Moreover, an external approach to counteract the luminescent coupling effect was provided and the luminescent coupling process in a top-limited solar cell was illustrated. Finally, the bias and wavelength dependence of luminescent coupling efficiency was applied to the 3D circuit model and the simulation results were consistent with the measured data.
{"title":"A simulation study on the bias and wavelength dependence of luminescent coupling in top-limited multi-junction solar cells","authors":"He Wan, Chen Benyuan, Lv Qinghua, Lv Hui","doi":"10.1093/ijlct/ctad057","DOIUrl":"https://doi.org/10.1093/ijlct/ctad057","url":null,"abstract":"\u0000 Luminescent coupling in a top-limited multi-junction solar cell was investigated by employing a 3D circuit model and semiconductor physics. The calculation methods for computing both electro-luminescent and photo-luminescent coupling efficiencies were introduced. Since the calculation processes were circuit independent, they can be applied directly to any form of an equivalent circuit model of a solar cell. Moreover, an external approach to counteract the luminescent coupling effect was provided and the luminescent coupling process in a top-limited solar cell was illustrated. Finally, the bias and wavelength dependence of luminescent coupling efficiency was applied to the 3D circuit model and the simulation results were consistent with the measured data.","PeriodicalId":14118,"journal":{"name":"International Journal of Low-carbon Technologies","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44590480","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Dlimi, F. Elmourabit, Fatima Id Ouissaaden, A. Khoukh, L. Limouny, E. Baghaz, A. El Kaaouachi
In this manuscript, we have theoretically reanalyzed data prepared and already published by Foroughi et al.[1]. These data concern the thermal energy dependence of the electrical conductivity of the samples: Graphene fiber, graphene/Poly(3,4-ethylenedioxythiophene)(graphene/PEDOT), graphene/ carbone nanotube(graphene/CNT) and graphene/carbone nonotube/Poly(3,4-ethylenedioxythiophene)(graphene/CNT/PEDOT) composite fibers. We investigate the behavior of the thermal conductivity for these four samples. These samples are considered as thermoelectric materials or green energy conversion materials using the Seebeck effect to transform heat into electrical energy and vice versa. In this context, the optimization of the ZT merit factor remains a challenge for the scientific community. The objective of this investigation is to evaluate and characterize the thermoelectric efficiency of the above-mentioned samples. We confront the experimental data with the existing theoretical models. The thermoelectric efficiency is generally characterized by the merit factor ZT. The maximum ZT of about 1,2 is obtained in the graphene fiber and between 0,1 et 0,2 in the others samples. The performance of the material depends on ZT, indeed a high ZT ($ZTge 1$ ) corresponds to a better optimization of the composite.
{"title":"Analysis of thermoelectric effect of wet spun graphene fiber composites","authors":"S. Dlimi, F. Elmourabit, Fatima Id Ouissaaden, A. Khoukh, L. Limouny, E. Baghaz, A. El Kaaouachi","doi":"10.1093/ijlct/ctad055","DOIUrl":"https://doi.org/10.1093/ijlct/ctad055","url":null,"abstract":"\u0000 In this manuscript, we have theoretically reanalyzed data prepared and already published by Foroughi et al.[1]. These data concern the thermal energy dependence of the electrical conductivity of the samples: Graphene fiber, graphene/Poly(3,4-ethylenedioxythiophene)(graphene/PEDOT), graphene/ carbone nanotube(graphene/CNT) and graphene/carbone nonotube/Poly(3,4-ethylenedioxythiophene)(graphene/CNT/PEDOT) composite fibers. We investigate the behavior of the thermal conductivity for these four samples. These samples are considered as thermoelectric materials or green energy conversion materials using the Seebeck effect to transform heat into electrical energy and vice versa. In this context, the optimization of the ZT merit factor remains a challenge for the scientific community. The objective of this investigation is to evaluate and characterize the thermoelectric efficiency of the above-mentioned samples. We confront the experimental data with the existing theoretical models. The thermoelectric efficiency is generally characterized by the merit factor ZT. The maximum ZT of about 1,2 is obtained in the graphene fiber and between 0,1 et 0,2 in the others samples. The performance of the material depends on ZT, indeed a high ZT ($ZTge 1$ ) corresponds to a better optimization of the composite.","PeriodicalId":14118,"journal":{"name":"International Journal of Low-carbon Technologies","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43436911","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Alzara, A. Yosri, Amer Alruwaili, E. Cuce, S. M. Eldin, A. Ehab
The globe has been moving in the direction of using less energy and emitting fewer emissions in recent years, which has a variety of implications like causing climate change. Hence, the environmental analysis is essential today in construction sector to develop a good product with adequate performance, safety, with logical cost and friendly to environment. One of the most significant emissions from various stages in the building sector is carbon dioxide, which may be further separated into two categories: embedded emissions and operating emissions. This paper’s main goal is to introduce a simple tool integrated into a BIM-based framework that provides an analysis of embodied carbon (related to SE2050’s commitment to net zero) in order to produce a manual for designers to select the appropriate materials, systems, and alternatives during the design phase. The suggested integration procedure was carried out using Autodesk Revit (to produce the 3D model), Dynamo (a visual programming tool), and BIM360 (to link with), with good interoperability between each product. Finally, a case study is done to apply and validate this process to foresee that the tool can be ready to use, the results shows that the maximum variance was 0.047, this support developers’ environmental strategies, and enable clients and other stockholders to consider the environmental impact in the early phases of the construction projects.
{"title":"Dynamo script and a BIM-based process for measuring embodied carbon in buildings during the design phase","authors":"M. Alzara, A. Yosri, Amer Alruwaili, E. Cuce, S. M. Eldin, A. Ehab","doi":"10.1093/ijlct/ctad053","DOIUrl":"https://doi.org/10.1093/ijlct/ctad053","url":null,"abstract":"\u0000 The globe has been moving in the direction of using less energy and emitting fewer emissions in recent years, which has a variety of implications like causing climate change. Hence, the environmental analysis is essential today in construction sector to develop a good product with adequate performance, safety, with logical cost and friendly to environment. One of the most significant emissions from various stages in the building sector is carbon dioxide, which may be further separated into two categories: embedded emissions and operating emissions. This paper’s main goal is to introduce a simple tool integrated into a BIM-based framework that provides an analysis of embodied carbon (related to SE2050’s commitment to net zero) in order to produce a manual for designers to select the appropriate materials, systems, and alternatives during the design phase. The suggested integration procedure was carried out using Autodesk Revit (to produce the 3D model), Dynamo (a visual programming tool), and BIM360 (to link with), with good interoperability between each product. Finally, a case study is done to apply and validate this process to foresee that the tool can be ready to use, the results shows that the maximum variance was 0.047, this support developers’ environmental strategies, and enable clients and other stockholders to consider the environmental impact in the early phases of the construction projects.","PeriodicalId":14118,"journal":{"name":"International Journal of Low-carbon Technologies","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46107304","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
To combat climate change and promote sustainable engine development, the optimization of the turbocharger development process is necessary to decrease emissions and increase fuel economy. This paper presents the influence of trailing edge curves on the performance of the significantly small radial turbine impeller of an automotive turbocharger used in a 0.8-L two-cylinder gasoline engine by comparing numerical analysis results under two boundary conditions: a constant pressure ratio and constant mass flow rate. The curve of a trailing edge depends on several parameters; however, in this study, the exponent (n) was selected to modify the turbine impeller trailing edge profile, as it exhibits a more significant influence on the curve than other parameters. Hence, computational fluid dynamics (CFD) analyses were conducted on the radial turbine for various trailing edge curves under a constant pressure ratio and constant mass flow rate, and the results were compared. The results indicated that the efficiency improvement was negligible under the pressure ratio and mass flow rate conditions due to inadequate alterations. Nevertheless, a significant shaft power improvement was observed based on changes in the trailing edge curve under a constant pressure ratio. In contrast, the same changes caused a considerable decrease in the shaft power under a constant mass flow rate.
{"title":"Influence of trailing-edge curve on the performance of radial turbine in turbocharger","authors":"J. Yun, O. Atac, Jung-Bae Kim, Gi-Yong Kim","doi":"10.1093/ijlct/ctad045","DOIUrl":"https://doi.org/10.1093/ijlct/ctad045","url":null,"abstract":"\u0000 To combat climate change and promote sustainable engine development, the optimization of the turbocharger development process is necessary to decrease emissions and increase fuel economy. This paper presents the influence of trailing edge curves on the performance of the significantly small radial turbine impeller of an automotive turbocharger used in a 0.8-L two-cylinder gasoline engine by comparing numerical analysis results under two boundary conditions: a constant pressure ratio and constant mass flow rate. The curve of a trailing edge depends on several parameters; however, in this study, the exponent (n) was selected to modify the turbine impeller trailing edge profile, as it exhibits a more significant influence on the curve than other parameters. Hence, computational fluid dynamics (CFD) analyses were conducted on the radial turbine for various trailing edge curves under a constant pressure ratio and constant mass flow rate, and the results were compared. The results indicated that the efficiency improvement was negligible under the pressure ratio and mass flow rate conditions due to inadequate alterations. Nevertheless, a significant shaft power improvement was observed based on changes in the trailing edge curve under a constant pressure ratio. In contrast, the same changes caused a considerable decrease in the shaft power under a constant mass flow rate.","PeriodicalId":14118,"journal":{"name":"International Journal of Low-carbon Technologies","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47741922","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Climate action around the world has shifted to the potential of global warming contribution from the design and construction of infrastructures, especially those in demand for concrete. Concrete production and use have been identified as contributing to over 5% of the world’s greenhouse gas (GHG) emissions. The main aim of this research work is to critically study the net-zero and sustainability potentials, which the world can leverage on from the development, production, and flowability of the self-compacting concrete. The conventional concrete is made of over 50% of ordinary cement, which contributes to over 7% of the world’s GHG emissions. But, in 1988, a fluidized concrete, which compacts under its self-weight, known as the self-compacting concrete (SCC), was formed and developed to overcome the need for durability, skill, and manpower that were dwindling in Japan at the time. This concrete created a pathway for cement to be replaced partially or totally by certain pozzolanic materials, which function as viscosity modifying admixture (VMA) or high-water reducing agent (HWRA) or microencapsulated phase change materials (MPCM) in the concrete mix. However, research findings have shown that in order for these materials to alter the flowability of the SCC, there has to be reduced yield stress and moderate viscosity for allowable internal friction based on the Bingham model, and this has to be achieved under the same w/c ratio. Fortunately, the implication of the use of these admixtures as replacements for cement is that there is a reduced demand for cement production and use in cleaner concrete production and, as such, a reduced CO2 emission associated with this process.
{"title":"The net-zero and sustainability potential of SCC development, production and flowability in concrete structures","authors":"K. Onyelowe, Denise‐Penelope N. Kontoni","doi":"10.1093/ijlct/ctad033","DOIUrl":"https://doi.org/10.1093/ijlct/ctad033","url":null,"abstract":"\u0000 Climate action around the world has shifted to the potential of global warming contribution from the design and construction of infrastructures, especially those in demand for concrete. Concrete production and use have been identified as contributing to over 5% of the world’s greenhouse gas (GHG) emissions. The main aim of this research work is to critically study the net-zero and sustainability potentials, which the world can leverage on from the development, production, and flowability of the self-compacting concrete. The conventional concrete is made of over 50% of ordinary cement, which contributes to over 7% of the world’s GHG emissions. But, in 1988, a fluidized concrete, which compacts under its self-weight, known as the self-compacting concrete (SCC), was formed and developed to overcome the need for durability, skill, and manpower that were dwindling in Japan at the time. This concrete created a pathway for cement to be replaced partially or totally by certain pozzolanic materials, which function as viscosity modifying admixture (VMA) or high-water reducing agent (HWRA) or microencapsulated phase change materials (MPCM) in the concrete mix. However, research findings have shown that in order for these materials to alter the flowability of the SCC, there has to be reduced yield stress and moderate viscosity for allowable internal friction based on the Bingham model, and this has to be achieved under the same w/c ratio. Fortunately, the implication of the use of these admixtures as replacements for cement is that there is a reduced demand for cement production and use in cleaner concrete production and, as such, a reduced CO2 emission associated with this process.","PeriodicalId":14118,"journal":{"name":"International Journal of Low-carbon Technologies","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41924025","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Feng Gao, Chunpeng Yang, Rui Zhao, Jun-qiang Sang, Fanbin Meng, Liming Ren, Yaxiong Ji, Yuning Yang
Fracturing is an important means to realize the development value for tight sandstone unconventional reservoirs, which consumes serious water resources, and generates high viscosity of backflow fluid with the petroleum and suspended matter pollutants. Therefore, it is of great significance to recycle fracturing fluid from tight sandstone with low-carbon and environmental protection. In this study, the fracturing fluid of tight sandstone in a block of a certain oilfield was taken as the research object, and a comprehensive water quality analysis was carried out. And studied on the influence factors of oxidation gel breaking, flocculation sedimentation, ion removal, filtration and process optimization, it formed the combined process technology for resource treatment of fracturing flowback fluid in tight sandstone. After treatment, the mass concentration of iron ion in fracturing flowback fluid was less than 5 mg/L, the mass concentration of suspended matter was less than 10 mg/L, and the mass concentration of oil was less than 5 mg/L, which could meet the water quality requirements of fluid distribution and reuse, and avoid the environmental pollution risk of flowback fluid effectively; and while, the consumption level of water resources in fracturing construction also was greatly reduced. This paper will have positive significance for the resource treatment technology and development of tight sandstone fracturing fluid.
{"title":"Development of resource treatment Technology for Fracturing Backflow Fluids of tight sandstone","authors":"Feng Gao, Chunpeng Yang, Rui Zhao, Jun-qiang Sang, Fanbin Meng, Liming Ren, Yaxiong Ji, Yuning Yang","doi":"10.1093/ijlct/ctac121","DOIUrl":"https://doi.org/10.1093/ijlct/ctac121","url":null,"abstract":"\u0000 Fracturing is an important means to realize the development value for tight sandstone unconventional reservoirs, which consumes serious water resources, and generates high viscosity of backflow fluid with the petroleum and suspended matter pollutants. Therefore, it is of great significance to recycle fracturing fluid from tight sandstone with low-carbon and environmental protection. In this study, the fracturing fluid of tight sandstone in a block of a certain oilfield was taken as the research object, and a comprehensive water quality analysis was carried out. And studied on the influence factors of oxidation gel breaking, flocculation sedimentation, ion removal, filtration and process optimization, it formed the combined process technology for resource treatment of fracturing flowback fluid in tight sandstone. After treatment, the mass concentration of iron ion in fracturing flowback fluid was less than 5 mg/L, the mass concentration of suspended matter was less than 10 mg/L, and the mass concentration of oil was less than 5 mg/L, which could meet the water quality requirements of fluid distribution and reuse, and avoid the environmental pollution risk of flowback fluid effectively; and while, the consumption level of water resources in fracturing construction also was greatly reduced. This paper will have positive significance for the resource treatment technology and development of tight sandstone fracturing fluid.","PeriodicalId":14118,"journal":{"name":"International Journal of Low-carbon Technologies","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47753544","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Eleonora Baccega, M. Bottarelli, F. J. G. Gallero, I. Maestre, G. Pei, Yuehong Su
The adoption of ventilated roofs and facades, as well as the integration of phase change materials (PCMs) in the building envelope, have proved to be effective as passive cooling techniques in reducing the solar heat gain through the building envelope during the summer period and, therefore, reduce the energy requirement for cooling. Even though much research focused on each of these strategies individually, their combination has not been deeply studied yet. Preliminary numerical studies were carried out on the application of PCMs on a pitched ventilated tiled roof and the most effective position turned out to be suspended in the middle of the above sheathing ventilation (ASV) channel. Based on this conclusion and exploiting an existing mock-up facility, two equivalent pitched ventilated roofs with an air gap of 4 cm were built as coverage of two identical rooms, each one equipped with a fan coil, one with a 0.007 m PCM layer suspended in the middle of the ASV and the other one without. They were then tested under real conditions at the TekneHub Laboratory at the University of Ferrara. The behaviour of the two configurations were compared in terms of temperature, velocity of the air in the ASV, heat flux, and energy requirement for cooling, which were monitored through T-type thermocouples, heat flow meter, anemometers and energy meters, respectively. The aim of the research was to validate the numerical results and confirm that the combination of the two strategies allows further improvement of roof performance.
{"title":"Improving thermal performance of a ventilated tiled roof by using phase change materials","authors":"Eleonora Baccega, M. Bottarelli, F. J. G. Gallero, I. Maestre, G. Pei, Yuehong Su","doi":"10.1093/ijlct/ctad047","DOIUrl":"https://doi.org/10.1093/ijlct/ctad047","url":null,"abstract":"\u0000 The adoption of ventilated roofs and facades, as well as the integration of phase change materials (PCMs) in the building envelope, have proved to be effective as passive cooling techniques in reducing the solar heat gain through the building envelope during the summer period and, therefore, reduce the energy requirement for cooling. Even though much research focused on each of these strategies individually, their combination has not been deeply studied yet. Preliminary numerical studies were carried out on the application of PCMs on a pitched ventilated tiled roof and the most effective position turned out to be suspended in the middle of the above sheathing ventilation (ASV) channel. Based on this conclusion and exploiting an existing mock-up facility, two equivalent pitched ventilated roofs with an air gap of 4 cm were built as coverage of two identical rooms, each one equipped with a fan coil, one with a 0.007 m PCM layer suspended in the middle of the ASV and the other one without. They were then tested under real conditions at the TekneHub Laboratory at the University of Ferrara. The behaviour of the two configurations were compared in terms of temperature, velocity of the air in the ASV, heat flux, and energy requirement for cooling, which were monitored through T-type thermocouples, heat flow meter, anemometers and energy meters, respectively. The aim of the research was to validate the numerical results and confirm that the combination of the two strategies allows further improvement of roof performance.","PeriodicalId":14118,"journal":{"name":"International Journal of Low-carbon Technologies","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48390412","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A 3-D falling film flow model outside the horizontal tube is established to study the influence of the liquid column impact the wall on the liquid film thickness distribution. It is found that the liquid film thickness fluctuates significantly at 0 ° - 60 ° in single liquid column, and the minimum thickness appears. In the jet flow, there is a critical value of 70° due to the liquid film fluctuation. The liquid film thickness change before 70° was negatively correlated with Reynolds number, and positively correlated after 70°. And the fluctuation amplitude negatively correlates with the Reynolds number.
{"title":"Influence of liquid column impact wall on liquid film thickness fluctuation outside the horizontal tube","authors":"Lele Chen, Q. Qiu, Xiaocui Zhang, Kun Zhang","doi":"10.1093/ijlct/ctac116","DOIUrl":"https://doi.org/10.1093/ijlct/ctac116","url":null,"abstract":"\u0000 A 3-D falling film flow model outside the horizontal tube is established to study the influence of the liquid column impact the wall on the liquid film thickness distribution. It is found that the liquid film thickness fluctuates significantly at 0 ° - 60 ° in single liquid column, and the minimum thickness appears. In the jet flow, there is a critical value of 70° due to the liquid film fluctuation. The liquid film thickness change before 70° was negatively correlated with Reynolds number, and positively correlated after 70°. And the fluctuation amplitude negatively correlates with the Reynolds number.","PeriodicalId":14118,"journal":{"name":"International Journal of Low-carbon Technologies","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45269331","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper analyzed the time-varying dependence and structural dependence between EU allowances (EUAs) and certified emission reductions (CERs) by using price fluctuation data from 2008 to 2021 on EU ETS. It was found that (1) there was a strong nonlinear spillover relationship between EUAs and CERs. From March 14, 2008 to March 16, 2012, the time-varying dependence values of EUAs and CERs were mostly between 0.6 and 1, and the mean coefficient of dependence was 0.86, showing a strong interdependence. From March 17, 2012 to January 2, 2017, the correlation between them was mostly below 0.6, and the mean coefficient of dependence fell to 0.25. This indicates that the dependency between EUA futures and CER futures was very low at this stage. However, in general, the mean value of dependence was above 0.55, that is, there was a dependency between them. (2) From March 14, 2008 to January 2, 2017, there were twelve structural mutation points in EUA and CER yield sequences. After four mutation points, the dependence coefficient increased, and the structural dependence enhanced. Meanwhile, after eight mutation points, the dependence coefficient decreased and the structural dependence weakened. The overall level remained above 0.6, showing the existence of structural dependence. (3) Abrupt changes in EUA and CER prices were closely related to the promulgation of major policies and unpredictable emergencies. The former caused carbon prices to fluctuate slightly. When the period of change was short and the recovery was rapid, it caused sharp fluctuations in carbon prices. When the duration of change was long, and the recovery was slow, it yielded impacts that extend far beyond the publication of important information.
{"title":"Asymmetric time-varying dependence and variable structure dependence measurement and analysis of EUA and CER","authors":"Xing Yang, Yijing Ye, Jia-wen Li, Jun-long Mi","doi":"10.1093/ijlct/ctad036","DOIUrl":"https://doi.org/10.1093/ijlct/ctad036","url":null,"abstract":"\u0000 This paper analyzed the time-varying dependence and structural dependence between EU allowances (EUAs) and certified emission reductions (CERs) by using price fluctuation data from 2008 to 2021 on EU ETS. It was found that (1) there was a strong nonlinear spillover relationship between EUAs and CERs. From March 14, 2008 to March 16, 2012, the time-varying dependence values of EUAs and CERs were mostly between 0.6 and 1, and the mean coefficient of dependence was 0.86, showing a strong interdependence. From March 17, 2012 to January 2, 2017, the correlation between them was mostly below 0.6, and the mean coefficient of dependence fell to 0.25. This indicates that the dependency between EUA futures and CER futures was very low at this stage. However, in general, the mean value of dependence was above 0.55, that is, there was a dependency between them. (2) From March 14, 2008 to January 2, 2017, there were twelve structural mutation points in EUA and CER yield sequences. After four mutation points, the dependence coefficient increased, and the structural dependence enhanced. Meanwhile, after eight mutation points, the dependence coefficient decreased and the structural dependence weakened. The overall level remained above 0.6, showing the existence of structural dependence. (3) Abrupt changes in EUA and CER prices were closely related to the promulgation of major policies and unpredictable emergencies. The former caused carbon prices to fluctuate slightly. When the period of change was short and the recovery was rapid, it caused sharp fluctuations in carbon prices. When the duration of change was long, and the recovery was slow, it yielded impacts that extend far beyond the publication of important information.","PeriodicalId":14118,"journal":{"name":"International Journal of Low-carbon Technologies","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41609142","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Alla, L. Bammou, S. Alami, M. Najim, A. Charef, Said Bouchta, M. Errai, M. Feddaoui
The need for freshwater supply in different parts of the world has given great interest to the study of seawater desalination which has led to the development of various innovative techniques in this field. The present numerical study contributes to the improvement of the evaporative desalination operation by introducing nanoparticles into the base fluid. The desalination technique considered in this study consists of a saltwater film falling along the inner wall of a vertical channel heated uniformly by a constant heat flux. The equations governing the flow and the heat and mass transfer associated with the boundary and interface conditions are solved numerically using the finite difference method. We considered two values of salinity, 10 g.kg-1 and 39 g.kg-1 which correspond respectively to brackish water and sea water with different types and volume fractions of nanoparticles in order to study the effect of the combination of these parameters on the enhancement of desalination by evaporation. The results showed that the evaporation process by injecting nanoparticles into salt water improves due to its positive effect on thermophysical properties. In addition, Al2O3 is significantly better for evaporative desalination than TiO2 and copper. Moreover, we can achieve the same heat and mass transfer performance by using 2% alumina instead of 4% TiO2.
{"title":"Effect of nanoparticles on the evaporation of a salt water film.","authors":"A. Alla, L. Bammou, S. Alami, M. Najim, A. Charef, Said Bouchta, M. Errai, M. Feddaoui","doi":"10.1093/ijlct/ctad035","DOIUrl":"https://doi.org/10.1093/ijlct/ctad035","url":null,"abstract":"\u0000 The need for freshwater supply in different parts of the world has given great interest to the study of seawater desalination which has led to the development of various innovative techniques in this field. The present numerical study contributes to the improvement of the evaporative desalination operation by introducing nanoparticles into the base fluid. The desalination technique considered in this study consists of a saltwater film falling along the inner wall of a vertical channel heated uniformly by a constant heat flux. The equations governing the flow and the heat and mass transfer associated with the boundary and interface conditions are solved numerically using the finite difference method. We considered two values of salinity, 10 g.kg-1 and 39 g.kg-1 which correspond respectively to brackish water and sea water with different types and volume fractions of nanoparticles in order to study the effect of the combination of these parameters on the enhancement of desalination by evaporation. The results showed that the evaporation process by injecting nanoparticles into salt water improves due to its positive effect on thermophysical properties. In addition, Al2O3 is significantly better for evaporative desalination than TiO2 and copper. Moreover, we can achieve the same heat and mass transfer performance by using 2% alumina instead of 4% TiO2.","PeriodicalId":14118,"journal":{"name":"International Journal of Low-carbon Technologies","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44175174","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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