The vast range of applications for enzymes in the production of biofuels has led to a major increase in market demand in recent years. Cellulase's high cost and poor catalytic efficiency are two key barriers to the industrial usage of lignocellulosic biomass as feedstocks for fuels in biorefineries. In this study, the economic evaluation of cellulase production in solid-state fermentation was done by designing two process routes (batch and semi-batch) to optimize the process. SuperPro Designer Software has been used to create a process model that assessed the economics of fermentation operations while Monte Carlo Software was used to conduct the sensitivity analysis investigation. The impacts of cellulase yield, productivity, aeration rate, and specific power input on the unit production cost (UPC) of cellulase enzyme were studied. The batch procedure requires more sterilized air for the aerobic fermentation process than the semi-batch approach, according to the results. In comparison to the batch fermentation process, the semi-batch approach had a payback period of less than 2 years, an internal rate of return of 39.14%, and a net present value of $142,089,000. The semi-batch process approach has a higher economic feasibility when compared with the batch fermentation process since it is more certain to attain its base case value of UPC at the maximum. This research was key to developing a process pathway that reduces cellulase production costs in solid state fermentation while improving market supply for its use in a biorefinery to produce sustainable fuel.
{"title":"Economic assessment of cellulase production in batch and semi-batch solid state fermentation processes","authors":"A. Taiwo, Andykan Tom-James, P. Musonge","doi":"10.1093/ijlct/ctad009","DOIUrl":"https://doi.org/10.1093/ijlct/ctad009","url":null,"abstract":"\u0000 The vast range of applications for enzymes in the production of biofuels has led to a major increase in market demand in recent years. Cellulase's high cost and poor catalytic efficiency are two key barriers to the industrial usage of lignocellulosic biomass as feedstocks for fuels in biorefineries. In this study, the economic evaluation of cellulase production in solid-state fermentation was done by designing two process routes (batch and semi-batch) to optimize the process. SuperPro Designer Software has been used to create a process model that assessed the economics of fermentation operations while Monte Carlo Software was used to conduct the sensitivity analysis investigation. The impacts of cellulase yield, productivity, aeration rate, and specific power input on the unit production cost (UPC) of cellulase enzyme were studied. The batch procedure requires more sterilized air for the aerobic fermentation process than the semi-batch approach, according to the results. In comparison to the batch fermentation process, the semi-batch approach had a payback period of less than 2 years, an internal rate of return of 39.14%, and a net present value of $142,089,000. The semi-batch process approach has a higher economic feasibility when compared with the batch fermentation process since it is more certain to attain its base case value of UPC at the maximum. This research was key to developing a process pathway that reduces cellulase production costs in solid state fermentation while improving market supply for its use in a biorefinery to produce sustainable fuel.","PeriodicalId":14118,"journal":{"name":"International Journal of Low-carbon Technologies","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46205612","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. Ebid, K. Onyelowe, Denise‐Penelope N. Kontoni, Alberto Quintana Gallardo, Shadi Hanandeh
Thermal characteristics of concrete is one of the main topics in concrete technology researches. They were extensively studied since the 80's to predict the behavior of the concrete in fire and the performance of massive concrete. However, this topic was raised again after 2010 as a part of sustainable, energy effective and ecofriendly buildings studies. The aim of this research is to present a comparison between the thermal characteristics of self-compacted concrete (SCC) and the geopolymer concrete (GPC) using collected previous researches. More than fifty references were collected, sorted and analyzed in the last forty years. The results showed that (GPC) has better thermal characteristics such as thermal conductivity, heat capacity, fire resistance, while (SCC) has better mechanical properties such as compressive strength, early strength and elastic modulus. Besides that, from ecological point of view, partially replacing of ordinary Portland cement (OPC) with microencapsulated phase change materials (MPCM) such as fly ash, silica fume, slag, and metakaolin remarkably decreases the CO2 footprint of construction industry.
{"title":"Heat and mass transfer in different concrete structures: a study of self-compacting concrete and geopolymer concrete","authors":"A. Ebid, K. Onyelowe, Denise‐Penelope N. Kontoni, Alberto Quintana Gallardo, Shadi Hanandeh","doi":"10.1093/ijlct/ctad022","DOIUrl":"https://doi.org/10.1093/ijlct/ctad022","url":null,"abstract":"\u0000 Thermal characteristics of concrete is one of the main topics in concrete technology researches. They were extensively studied since the 80's to predict the behavior of the concrete in fire and the performance of massive concrete. However, this topic was raised again after 2010 as a part of sustainable, energy effective and ecofriendly buildings studies. The aim of this research is to present a comparison between the thermal characteristics of self-compacted concrete (SCC) and the geopolymer concrete (GPC) using collected previous researches. More than fifty references were collected, sorted and analyzed in the last forty years. The results showed that (GPC) has better thermal characteristics such as thermal conductivity, heat capacity, fire resistance, while (SCC) has better mechanical properties such as compressive strength, early strength and elastic modulus. Besides that, from ecological point of view, partially replacing of ordinary Portland cement (OPC) with microencapsulated phase change materials (MPCM) such as fly ash, silica fume, slag, and metakaolin remarkably decreases the CO2 footprint of construction industry.","PeriodicalId":14118,"journal":{"name":"International Journal of Low-carbon Technologies","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46347477","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}
Cold chain logistics distribution orders have increased due to the impact of COVID-19. In view of the increasing difficulty of route optimization and the increase of carbon emissions in the process of cold chain logistics distribution, a mathematical model for route optimization of cold chain logistics distribution vehicles with minimum comprehensive cost is established by considering the cost of carbon emission intensity comprehensively in this paper. The main contributions of this paper are as follows:1.An improved hybrid ant colony algorithm is proposed, which combined simulated annealing algorithm to get rid of the local optimal solution.2. Chaotic mapping is introduced in pheromone update to accelerate convergence and improve search efficiency. The effectiveness of the proposed method in optimizing cold chain logistics distribution path and reducing costs is verified by simulation experiments and comparison with the existing classical algorithms.
{"title":"Research on cold chain logistics optimization model considering low carbon emissions","authors":"Ning Tao, Han Yumeng, Fu Meng","doi":"10.1093/ijlct/ctad021","DOIUrl":"https://doi.org/10.1093/ijlct/ctad021","url":null,"abstract":"\u0000 Cold chain logistics distribution orders have increased due to the impact of COVID-19. In view of the increasing difficulty of route optimization and the increase of carbon emissions in the process of cold chain logistics distribution, a mathematical model for route optimization of cold chain logistics distribution vehicles with minimum comprehensive cost is established by considering the cost of carbon emission intensity comprehensively in this paper.\u0000 The main contributions of this paper are as follows:1.An improved hybrid ant colony algorithm is proposed, which combined simulated annealing algorithm to get rid of the local optimal solution.2. Chaotic mapping is introduced in pheromone update to accelerate convergence and improve search efficiency. The effectiveness of the proposed method in optimizing cold chain logistics distribution path and reducing costs is verified by simulation experiments and comparison with the existing classical algorithms.","PeriodicalId":14118,"journal":{"name":"International Journal of Low-carbon Technologies","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41605294","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}
Yong Yang, Xiaotong Ren, Yiqiao Li, Ning Wang, Kun Zhang, Shengqiang Shen
In the new era of ejector technology entering into system scale from device scale. The methodology of regulation mode of adjustable ejector has been summarized in the paper. The similarity characteristics of qualitative and quantitative regulation under different operating modes are researched. The results show that both quantitative and quantitative regulation have the characteristics of "constant capacity". Three different “constant capacity” phenomena in ejector have been found, and the similarity indicates that the turbulent flow in ejector has some statistical invariances in form of mass flow rate of jetting flow. The ejector has the similar entrainment ability by increasing primary pressure by 43% in qualitative regulation mode or enlarging the nozzle throat opening by 47% in quantitative regulation mode under critical mode with similar under-expanded state. The advantages of adjustable ejector have been promoted, especially ±5% regulation accuracy or really constant regulation ability, discharging improved ability by 80% in flow rate or 10% in pressure lifting ability in subcritical mode, or primary flow rate saving ability by 25% or 13% in pressure lifting ability in critical mode.
{"title":"Similarity characteristics of qualitative and quantitative regulation for adjustable ejector","authors":"Yong Yang, Xiaotong Ren, Yiqiao Li, Ning Wang, Kun Zhang, Shengqiang Shen","doi":"10.1093/ijlct/ctad030","DOIUrl":"https://doi.org/10.1093/ijlct/ctad030","url":null,"abstract":"\u0000 In the new era of ejector technology entering into system scale from device scale. The methodology of regulation mode of adjustable ejector has been summarized in the paper. The similarity characteristics of qualitative and quantitative regulation under different operating modes are researched. The results show that both quantitative and quantitative regulation have the characteristics of \"constant capacity\". Three different “constant capacity” phenomena in ejector have been found, and the similarity indicates that the turbulent flow in ejector has some statistical invariances in form of mass flow rate of jetting flow. The ejector has the similar entrainment ability by increasing primary pressure by 43% in qualitative regulation mode or enlarging the nozzle throat opening by 47% in quantitative regulation mode under critical mode with similar under-expanded state. The advantages of adjustable ejector have been promoted, especially ±5% regulation accuracy or really constant regulation ability, discharging improved ability by 80% in flow rate or 10% in pressure lifting ability in subcritical mode, or primary flow rate saving ability by 25% or 13% in pressure lifting ability in critical mode.","PeriodicalId":14118,"journal":{"name":"International Journal of Low-carbon Technologies","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49514110","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 more rapid development of smart manufacturing system (SMS) within the automotive industry will significantly promote its competitiveness which is essential to the economic sustainable development of South Africa. From recent research studies, the automotive sector contributes over 7% to the annual gross domestic product (GDP) of South Africa and its sustainability is important to the segment through SMS. Thus, the SMS deserves greater focus from the Government and the industry. Smart manufacturing technology utilises machines and tools which are interconnected for the improvement of manufacturing system and energy optimization. The benefits of SMS include cost reduction, increased productivity, product customization, resources efficiency, and minimization of negative environmental impacts. Globally, the automotive industry puts significant emphasis on SMS, considering the on-going substantial initiatives. In order to achieve SMS, ultramodern technologies in different areas, varying from Cyber-Physical Systems (CPS), smart sensors, complex and large data analytics, Internet of things (IoT), cloud manufacturing, and to additive manufacturing, energy reduction, and hologram, are being established and employed in manufacturing locations. Therefore, this study is aimed at technologies and toolkits development that will increase the implementation and responsiveness of SMS among automotive manufacturers and supports decision-makers in planning better Smart Manufacturing Systems capabilities.
{"title":"Application of sustainable smart manufacturing technologies and toolkits in the automotive industry","authors":"V. Inyang, G. Kanakana, O. Laseinde","doi":"10.1093/ijlct/ctad023","DOIUrl":"https://doi.org/10.1093/ijlct/ctad023","url":null,"abstract":"\u0000 A more rapid development of smart manufacturing system (SMS) within the automotive industry will significantly promote its competitiveness which is essential to the economic sustainable development of South Africa. From recent research studies, the automotive sector contributes over 7% to the annual gross domestic product (GDP) of South Africa and its sustainability is important to the segment through SMS. Thus, the SMS deserves greater focus from the Government and the industry. Smart manufacturing technology utilises machines and tools which are interconnected for the improvement of manufacturing system and energy optimization. The benefits of SMS include cost reduction, increased productivity, product customization, resources efficiency, and minimization of negative environmental impacts. Globally, the automotive industry puts significant emphasis on SMS, considering the on-going substantial initiatives. In order to achieve SMS, ultramodern technologies in different areas, varying from Cyber-Physical Systems (CPS), smart sensors, complex and large data analytics, Internet of things (IoT), cloud manufacturing, and to additive manufacturing, energy reduction, and hologram, are being established and employed in manufacturing locations. Therefore, this study is aimed at technologies and toolkits development that will increase the implementation and responsiveness of SMS among automotive manufacturers and supports decision-makers in planning better Smart Manufacturing Systems capabilities.","PeriodicalId":14118,"journal":{"name":"International Journal of Low-carbon Technologies","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45503608","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 proposes a method for predicting the generation voltage of a solid oxide fuel cell based on the data results of a stand-alone solid oxide fuel single cell (SOFC) simulation model under ideal conditions, with the aim of improving the generation efficiency and extending the service life of the solid oxide fuel cell. In this paper, a modified BP neural network algorithm is used to improve the prediction accuracy of the solid oxide fuel cell generation voltage by using the whale algorithm to optimize the BP neural network model to improve its convergence and achieve the effect of improving the prediction accuracy. Firstly, the characteristics of the independent solid oxide fuel cell are introduced and simulated. Second, the long short-term memory network model (LSTM), linear regression network model and BP neural network are simulated and compared, and the results show that the BP neural network prediction model is more accurate and can be optimized and improved. Finally, the BP neural network is optimized and simulated using the whale algorithm, and the simulation results show that the method has better convergence and higher prediction accuracy than the traditional BP neural network prediction model.
{"title":"Optimization of solid oxide fuel cell power generation voltage prediction based on improved neural network","authors":"Liming Wei, Yixuan Wang","doi":"10.1093/ijlct/ctad028","DOIUrl":"https://doi.org/10.1093/ijlct/ctad028","url":null,"abstract":"\u0000 This paper proposes a method for predicting the generation voltage of a solid oxide fuel cell based on the data results of a stand-alone solid oxide fuel single cell (SOFC) simulation model under ideal conditions, with the aim of improving the generation efficiency and extending the service life of the solid oxide fuel cell. In this paper, a modified BP neural network algorithm is used to improve the prediction accuracy of the solid oxide fuel cell generation voltage by using the whale algorithm to optimize the BP neural network model to improve its convergence and achieve the effect of improving the prediction accuracy. Firstly, the characteristics of the independent solid oxide fuel cell are introduced and simulated. Second, the long short-term memory network model (LSTM), linear regression network model and BP neural network are simulated and compared, and the results show that the BP neural network prediction model is more accurate and can be optimized and improved. Finally, the BP neural network is optimized and simulated using the whale algorithm, and the simulation results show that the method has better convergence and higher prediction accuracy than the traditional BP neural network prediction model.","PeriodicalId":14118,"journal":{"name":"International Journal of Low-carbon Technologies","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44112404","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}
Phase change emulsions (PCMEs) are always identified as potential working fluids that could be used to reduce circulating pump energy consumption in chill water air conditioning systems. But how PCME behaves in a fin-and-tube heat exchanger is still unclear, which limited the application of such material. The paper focused on experimental studies of performance of a novel PCME, named as PCE-10, in a fin-andtube heat exchanger. The research analyzed heat transfer and flow behavior in fin-and-tube heat exchangers and the experimental results are compared with numercial studies published. Both studies showed that PCE-10 had its advantages as a cold storage medium, as PCE-10 did help to improve the heat transfer rate of heat exchanger by factor of 1.1-1.3 at the same flow rate compared with water.
{"title":"Experimental Investigations into Thermal Performance of Phase Change Emulsion in a Fin-and-tube Heat Exchanger","authors":"Cai-jie Wei, Jingjing Shao, J. Darkwa","doi":"10.1093/ijlct/ctad001","DOIUrl":"https://doi.org/10.1093/ijlct/ctad001","url":null,"abstract":"\u0000 Phase change emulsions (PCMEs) are always identified as potential working fluids that could be used to reduce circulating pump energy consumption in chill water air conditioning systems. But how PCME behaves in a fin-and-tube heat exchanger is still unclear, which limited the application of such material. The paper focused on experimental studies of performance of a novel PCME, named as PCE-10, in a fin-andtube heat exchanger. The research analyzed heat transfer and flow behavior in fin-and-tube heat exchangers and the experimental results are compared with numercial studies published. Both studies showed that PCE-10 had its advantages as a cold storage medium, as PCE-10 did help to improve the heat transfer rate of heat exchanger by factor of 1.1-1.3 at the same flow rate compared with water.","PeriodicalId":14118,"journal":{"name":"International Journal of Low-carbon Technologies","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46347104","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}
In the era of low-carbon economy, it is an important measure for enterprises to respond to changes in the external environment by actively investing in various low-carbon technologies to reduce their carbon emissions. However, in real life, simply focusing on one kind of technology investment may not be able to perfectly achieve the established goals of enterprises, and more often, enterprises will adopt a strategy of multiple technology investment. Therefore, in view of this practical activity, this paper considers that manufacturers invest in two innovative activities: reducing production costs and improving emission reduction. The results of this study show that the increase in the carbon trading price will stimulate the motivation of enterprises to carry out low-carbon technologies innovation, which is conducive to the realization of the government’s carbon emission reduction target. Under centralized decision-making, the R&D investment of enterprises will not achieve immediate results, and the carbon emissions of enterprises under centralized decision-making are relatively high compared with those under decentralized decision-making. The improvement of consumers’ low-carbon awareness will enhance the driving force of enterprises’ low-carbon technologies innovation, although it will not reduce the total carbon emissions of enterprises.
{"title":"Supply chain decision-making and coordination for joint investment in cost and carbon emission reduction","authors":"Ping Shi, X. Chen","doi":"10.1093/ijlct/ctad013","DOIUrl":"https://doi.org/10.1093/ijlct/ctad013","url":null,"abstract":"\u0000 In the era of low-carbon economy, it is an important measure for enterprises to respond to changes in the external environment by actively investing in various low-carbon technologies to reduce their carbon emissions. However, in real life, simply focusing on one kind of technology investment may not be able to perfectly achieve the established goals of enterprises, and more often, enterprises will adopt a strategy of multiple technology investment. Therefore, in view of this practical activity, this paper considers that manufacturers invest in two innovative activities: reducing production costs and improving emission reduction. The results of this study show that the increase in the carbon trading price will stimulate the motivation of enterprises to carry out low-carbon technologies innovation, which is conducive to the realization of the government’s carbon emission reduction target. Under centralized decision-making, the R&D investment of enterprises will not achieve immediate results, and the carbon emissions of enterprises under centralized decision-making are relatively high compared with those under decentralized decision-making. The improvement of consumers’ low-carbon awareness will enhance the driving force of enterprises’ low-carbon technologies innovation, although it will not reduce the total carbon emissions of enterprises.","PeriodicalId":14118,"journal":{"name":"International Journal of Low-carbon Technologies","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49412689","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 clarify the influencing mechanisms of the experimental condition and the tube structure on the pressure drop of heat transfer fluid, the two-phase flow condensation pressure drop of R134a inside the micro-fin tube was experimental studied at high mass flux, which is different from other conventional researches. The experimental result shows the pressure drop is proportional to mass flux and fin helical angle, and is inversely proportional to condensation temperature and coolant Reynolds number. Moreover, the experimental data of pressure drop was compared with the predicted value of some existing correlations for the micro-fin tube. It can be found that correlations of Cavallini et al, Han et al and Haraguchi et al show a good prediction effect with the mean relative deviation of 13.89%, 16.08% and -2.19%, respectively. Correlations of Pierre/0.053, Kedzierski et al and Choi et al all underestimate most of the experimental data of the pressure drop inside the tube, and their prediction deviations are greater than 10%. That is, the application effect of the separated flow model is better than that of the homogeneous flow model. Finally, the Kedzierski et al correlation was improved to realize a high-precision prediction of the fluid flow mechanism inside the tube. Because the prediction deviation of the improved correlation between the experimental value and the predicted value was greatly reduced, its prediction deviation is less than 10% for R134a and R410A, therefore, it can be say the improved correlation has a good predictive results for the pressure drop.
{"title":"Experimental investigation on flow condensation pressure drop of R134a inside the micro-fin tube at high mass flux","authors":"Q. Fuqiang, X. Taoping, Dugui He, D. Juanli","doi":"10.1093/ijlct/ctad016","DOIUrl":"https://doi.org/10.1093/ijlct/ctad016","url":null,"abstract":"\u0000 To clarify the influencing mechanisms of the experimental condition and the tube structure on the pressure drop of heat transfer fluid, the two-phase flow condensation pressure drop of R134a inside the micro-fin tube was experimental studied at high mass flux, which is different from other conventional researches. The experimental result shows the pressure drop is proportional to mass flux and fin helical angle, and is inversely proportional to condensation temperature and coolant Reynolds number. Moreover, the experimental data of pressure drop was compared with the predicted value of some existing correlations for the micro-fin tube. It can be found that correlations of Cavallini et al, Han et al and Haraguchi et al show a good prediction effect with the mean relative deviation of 13.89%, 16.08% and -2.19%, respectively. Correlations of Pierre/0.053, Kedzierski et al and Choi et al all underestimate most of the experimental data of the pressure drop inside the tube, and their prediction deviations are greater than 10%. That is, the application effect of the separated flow model is better than that of the homogeneous flow model. Finally, the Kedzierski et al correlation was improved to realize a high-precision prediction of the fluid flow mechanism inside the tube. Because the prediction deviation of the improved correlation between the experimental value and the predicted value was greatly reduced, its prediction deviation is less than 10% for R134a and R410A, therefore, it can be say the improved correlation has a good predictive results for the pressure drop.","PeriodicalId":14118,"journal":{"name":"International Journal of Low-carbon Technologies","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42182727","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}
Hang Li, Yang Ming, Ling Li, Ping Chen, Zhanqiang Zhang, Li-bo Zhou, Juntong Li, Kai Yao, Linan Dun
In this paper, S95 grade ultrafine mineral admixture was prepared by water quenched manganese slag and fly ash 1:1 compound mechanical ball milling to a specific surface area of 714 m2/kg. Its activity index was 86.8% at 7d and 96.3% at 28d. The S95 ultrafine mineral admixture prepared by ball milling has the characteristics of small particle size, high specific surface and high activity. Mixing with powders of different particle sizes, such as cement and silica fume, is helpful to improve particle gradation, reduce its pore structure and increase its compacting property for UHPC whose raw materials are fine aggregate. Ultra-high performance concrete (UHPC) was prepared by using the obtained ultrafine mineral admixture based on orthogonal test. The effects of different factors on the workability, mechanical properties, hydration heat and microstructure of UHPC were studied. The results show that when the silica fume content is 10%, the mineral admixture content is 10%, the binder-sand ratio is 1.1, and the water-binder ratio is 0.17, the fluidity of UHPC slurry can reach 261 mm, the compressive strength of 7d and 28d age can reach 128 MPa and 154.6 MPa, respectively. The hydration heat release of cementitious materials in 3d was 139.8 J/g. In terms of solid waste resource utilization, S95 grade ultrafine mineral admixture prepared by water-quench manganese slag and fly ash can replace 10% silica fume for the preparation of UHPC. It can not only solve the utilization problem of high added value of water quench manganese slag, but also reduce the preparation cost of UHPC to a certain extent.
本文采用水淬锰渣与粉煤灰1:1复合机械球磨法制备了S95级超细矿物掺合料，比表面积为714 m2/kg。7d和28d的活性指数分别为86.8%和96.3%。采用球磨法制备的S95超细矿物掺合料具有粒径小、比表面积高、活性高等特点。对于以细骨料为原料的UHPC，掺入水泥、硅灰等不同粒径的粉体，有利于提高颗粒级配，减小孔隙结构，提高压实性能。利用所获得的超细矿物掺合料进行正交试验，制备了超高性能混凝土。研究了不同因素对UHPC和易性、力学性能、水化热及微观结构的影响。结果表明:当硅灰掺量为10%、矿物掺量为10%、胶砂比为1.1、水胶比为0.17时，UHPC料浆的流动性可达261 mm, 7d和28d龄期抗压强度分别可达128 MPa和154.6 MPa。胶凝材料三维水化热释放量为139.8 J/g。在固废资源化利用方面，以水淬锰渣与粉煤灰配制的S95级超细矿物掺合料可替代10%的硅灰制备UHPC。既能解决水淬锰渣高附加值的利用问题，又能在一定程度上降低UHPC的制备成本。
{"title":"Preparation of water-quenched manganese slag and fly ash ultrafine mineral admixture and its application in UHPC","authors":"Hang Li, Yang Ming, Ling Li, Ping Chen, Zhanqiang Zhang, Li-bo Zhou, Juntong Li, Kai Yao, Linan Dun","doi":"10.1093/ijlct/ctac143","DOIUrl":"https://doi.org/10.1093/ijlct/ctac143","url":null,"abstract":"\u0000 In this paper, S95 grade ultrafine mineral admixture was prepared by water quenched manganese slag and fly ash 1:1 compound mechanical ball milling to a specific surface area of 714 m2/kg. Its activity index was 86.8% at 7d and 96.3% at 28d. The S95 ultrafine mineral admixture prepared by ball milling has the characteristics of small particle size, high specific surface and high activity. Mixing with powders of different particle sizes, such as cement and silica fume, is helpful to improve particle gradation, reduce its pore structure and increase its compacting property for UHPC whose raw materials are fine aggregate. Ultra-high performance concrete (UHPC) was prepared by using the obtained ultrafine mineral admixture based on orthogonal test. The effects of different factors on the workability, mechanical properties, hydration heat and microstructure of UHPC were studied. The results show that when the silica fume content is 10%, the mineral admixture content is 10%, the binder-sand ratio is 1.1, and the water-binder ratio is 0.17, the fluidity of UHPC slurry can reach 261 mm, the compressive strength of 7d and 28d age can reach 128 MPa and 154.6 MPa, respectively. The hydration heat release of cementitious materials in 3d was 139.8 J/g. In terms of solid waste resource utilization, S95 grade ultrafine mineral admixture prepared by water-quench manganese slag and fly ash can replace 10% silica fume for the preparation of UHPC. It can not only solve the utilization problem of high added value of water quench manganese slag, but also reduce the preparation cost of UHPC to a certain extent.","PeriodicalId":14118,"journal":{"name":"International Journal of Low-carbon Technologies","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47535433","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：