In thermal power plants, during the boilers functioning, heterogeneous deposits of substances must often be removed in order to prolong their operation and avoid their deterioration. The nature, type and quantity of deposits depend on the characteristics of the water supply systems and the chemical operating regime. For boilers with high deposits of copper and iron, the utilization of mineral acids for chemical cleaning is not quite effective, because their surfaces may be covered with a metal copper film. Organic impurities in the water supply affect the operation of steam generators, increasing electrical conductivity and lowering the pH. The heterogeneous composition of the deposits is unevenly distributed in the combustion system, making its cleaning a complex problem. For efficient chemical cleaning, the agents must have a minimal corrosive action on the metal surfaces, ensuring only the dissolution of the compounds on the surface of the boilers. To prevent corrosion of metals, inhibitors are introduced to diminish the reactions on the metal surface or at least to delay the kinetics of the reaction. This paper analyzes the implications of organic pollutants in the corrosion phenomena and chemical processes where they are involved. As an example, the power plant Borzesti affiliated to the Petrochemical Platform, Bacau County, Romania is presented. The adopted solution uses as an inhibitor, a synthesis between amino alcohol and a thiazole, in the presence of water. This inhibitor has been tested in the laboratory on different steels used in energy pipes, in different areas of the thermal circuits in the boiler, as pure steel or with different alloys. The methods used to reduce the effects of corrosion are briefly presented. Four classes of organic substances with properties of corrosion inhibitors in the organic acid environment were analyzed. The experimental results obtained, associated with a comparative analysis of corrosion rates, for different concentrations of inhibitors for a time interval of 4 hours are mentioned. In the second stage, the inhibitor behavior was analyzed for 6h and 8h. Corrosion rates are estimated by measuring the weight loss of the tested probes. Finally, the most suitable types of inhibitors, adapted at different metal compositions are presented, with a result in the cleaning of more than 98% of the surface of the boilers.
{"title":"New Solution With Syntheses Inhibitors for the Chemical Cleaning of Organic Pollutants From the Water Supply System Of Generators","authors":"V. Radulescu","doi":"10.1115/power2021-64314","DOIUrl":"https://doi.org/10.1115/power2021-64314","url":null,"abstract":"\u0000 In thermal power plants, during the boilers functioning, heterogeneous deposits of substances must often be removed in order to prolong their operation and avoid their deterioration. The nature, type and quantity of deposits depend on the characteristics of the water supply systems and the chemical operating regime. For boilers with high deposits of copper and iron, the utilization of mineral acids for chemical cleaning is not quite effective, because their surfaces may be covered with a metal copper film. Organic impurities in the water supply affect the operation of steam generators, increasing electrical conductivity and lowering the pH. The heterogeneous composition of the deposits is unevenly distributed in the combustion system, making its cleaning a complex problem. For efficient chemical cleaning, the agents must have a minimal corrosive action on the metal surfaces, ensuring only the dissolution of the compounds on the surface of the boilers. To prevent corrosion of metals, inhibitors are introduced to diminish the reactions on the metal surface or at least to delay the kinetics of the reaction. This paper analyzes the implications of organic pollutants in the corrosion phenomena and chemical processes where they are involved. As an example, the power plant Borzesti affiliated to the Petrochemical Platform, Bacau County, Romania is presented. The adopted solution uses as an inhibitor, a synthesis between amino alcohol and a thiazole, in the presence of water. This inhibitor has been tested in the laboratory on different steels used in energy pipes, in different areas of the thermal circuits in the boiler, as pure steel or with different alloys. The methods used to reduce the effects of corrosion are briefly presented. Four classes of organic substances with properties of corrosion inhibitors in the organic acid environment were analyzed. The experimental results obtained, associated with a comparative analysis of corrosion rates, for different concentrations of inhibitors for a time interval of 4 hours are mentioned. In the second stage, the inhibitor behavior was analyzed for 6h and 8h. Corrosion rates are estimated by measuring the weight loss of the tested probes. Finally, the most suitable types of inhibitors, adapted at different metal compositions are presented, with a result in the cleaning of more than 98% of the surface of the boilers.","PeriodicalId":8567,"journal":{"name":"ASME 2021 Power Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86585680","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}
S. Chakraborty, Abhirup Chaudhuri, Chirodeep Bakli
The water crisis affects the lives of millions over the world. Minimizing water losses in major water-consuming industries like power plants is of utmost importance. Since cooling towers lead to huge amounts of water loss, implementing modifications for recovering a fraction of this lost water in the exhaust has been a topic of active research. These modifications are often inspired by biological species, especially in arid regions, which have adapted in different ways by collecting water from fog, and hence biomimetic has become popular for water harvesting techniques. We revisit the fog collection technique most commonly used in nature and compare the relative merits of the same with surface texture and wettability. Arrays of spines of three different configurations were considered in this study — namely cuboidal, cylindrical and conical shapes. A theoretical model is developed to carry out a comparative analysis of these configurations considered. The effects of Laplace pressure gradient, gravity, topography and tilt angle on droplet transportation along the spines were explored to decipher the most efficient water transport and collection route. The observations are explained by performing extensive Molecular Dynamics (MD) simulations to bring out the interplay of surface tension and roughness at the contact line verifying the proposed formulations. The conical-shaped spines exhibited maximum transport and collection efficiency for zero tilt angle. Both cuboidal and cylindrical shaped spines showed little or no water collection when the spines are oriented horizontally. This is due to the Laplace pressure gradient which arises from varying radii of curvature of the conical shaped spine which drives the water droplets towards the base but is absent for the other two cases considered. On the contrary, when there is some finite tilt angle, the contribution of gravity comes into consideration and the water collection rate of the conical and cylindrical spines becomes comparable. Both Laplace pressure gradient and gravity help in water transport in the conical case whereas only gravity assists the water transport process for cylindrical spines. Still, the water collection rate is almost the same for these two scenarios due to enhanced coalescence of liquid droplets for the cylindrical case as is observed from MD simulations. As the droplets coalesce, they get larger and gravity aids the transport process by overcoming the solid-liquid interaction strength. Cuboidal shaped spines show the least efficiency with only gravity to assist the transport process and no coalescence is observed in this case. Moreover, the geometrical disparity makes the tips of conical spines more hydrophobic compared to the others which further ameliorates the water collection efficiency.
{"title":"Optimizing Water Harvesting on Bioinspired Surfaces: A Mesoscopic Perspective","authors":"S. Chakraborty, Abhirup Chaudhuri, Chirodeep Bakli","doi":"10.1115/power2021-64668","DOIUrl":"https://doi.org/10.1115/power2021-64668","url":null,"abstract":"\u0000 The water crisis affects the lives of millions over the world. Minimizing water losses in major water-consuming industries like power plants is of utmost importance. Since cooling towers lead to huge amounts of water loss, implementing modifications for recovering a fraction of this lost water in the exhaust has been a topic of active research. These modifications are often inspired by biological species, especially in arid regions, which have adapted in different ways by collecting water from fog, and hence biomimetic has become popular for water harvesting techniques. We revisit the fog collection technique most commonly used in nature and compare the relative merits of the same with surface texture and wettability. Arrays of spines of three different configurations were considered in this study — namely cuboidal, cylindrical and conical shapes. A theoretical model is developed to carry out a comparative analysis of these configurations considered. The effects of Laplace pressure gradient, gravity, topography and tilt angle on droplet transportation along the spines were explored to decipher the most efficient water transport and collection route. The observations are explained by performing extensive Molecular Dynamics (MD) simulations to bring out the interplay of surface tension and roughness at the contact line verifying the proposed formulations. The conical-shaped spines exhibited maximum transport and collection efficiency for zero tilt angle. Both cuboidal and cylindrical shaped spines showed little or no water collection when the spines are oriented horizontally. This is due to the Laplace pressure gradient which arises from varying radii of curvature of the conical shaped spine which drives the water droplets towards the base but is absent for the other two cases considered. On the contrary, when there is some finite tilt angle, the contribution of gravity comes into consideration and the water collection rate of the conical and cylindrical spines becomes comparable. Both Laplace pressure gradient and gravity help in water transport in the conical case whereas only gravity assists the water transport process for cylindrical spines. Still, the water collection rate is almost the same for these two scenarios due to enhanced coalescence of liquid droplets for the cylindrical case as is observed from MD simulations. As the droplets coalesce, they get larger and gravity aids the transport process by overcoming the solid-liquid interaction strength. Cuboidal shaped spines show the least efficiency with only gravity to assist the transport process and no coalescence is observed in this case. Moreover, the geometrical disparity makes the tips of conical spines more hydrophobic compared to the others which further ameliorates the water collection efficiency.","PeriodicalId":8567,"journal":{"name":"ASME 2021 Power Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84220855","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}
Operation of the generator with full converter and long tower cables leads to common mode and bearing current in the wind turbine. Common mode and bearing current are almost always present in such systems, due to the harmonics reflections within large tower cables. An electrical system should be carefully designed to perform in such environments. Bearing insulation thickness should be carefully chosen to minimize the impact of bearing current. Ideally these currents should flow through the dedicated path within the nacelle and pass through the tower to the ground. Due to complex structure of the nacelle in the onshore geared turbine and dealing with a very high frequency current, this is usually not the case. A complex cable routing and formation of different conducting path leads the common mode current to flows into an unexpected direction. It is the part of a good system design to monitor the path and evaluate the potential impact on the sensitive components to avoid potential failure in the field. A higher downtime of the turbine corresponds to a less reliable turbine, this is also closely associated with the levelized cost of electricity. This paper presents an overview of the system for the preferred common mode current routing and recommend various method by which formation of unwanted grounding loops can be avoided.
{"title":"Common Mode Current Effects and Challenges for Wind Turbine Generator Application","authors":"Gopal Singh, K. Sundaram","doi":"10.1115/power2021-63236","DOIUrl":"https://doi.org/10.1115/power2021-63236","url":null,"abstract":"\u0000 Operation of the generator with full converter and long tower cables leads to common mode and bearing current in the wind turbine. Common mode and bearing current are almost always present in such systems, due to the harmonics reflections within large tower cables. An electrical system should be carefully designed to perform in such environments. Bearing insulation thickness should be carefully chosen to minimize the impact of bearing current. Ideally these currents should flow through the dedicated path within the nacelle and pass through the tower to the ground. Due to complex structure of the nacelle in the onshore geared turbine and dealing with a very high frequency current, this is usually not the case. A complex cable routing and formation of different conducting path leads the common mode current to flows into an unexpected direction. It is the part of a good system design to monitor the path and evaluate the potential impact on the sensitive components to avoid potential failure in the field. A higher downtime of the turbine corresponds to a less reliable turbine, this is also closely associated with the levelized cost of electricity. This paper presents an overview of the system for the preferred common mode current routing and recommend various method by which formation of unwanted grounding loops can be avoided.","PeriodicalId":8567,"journal":{"name":"ASME 2021 Power Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89553240","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}
Due to the technological advancement in smart buildings and the smart grid, there is increasing desire of managing energy demand in buildings to achieve energy efficiency. In this context, building energy prediction has become an essential approach for measuring building energy performance, assessing energy system efficiency, and developing energy management strategies. In this study, two artificial intelligence techniques (i.e., ANN = artificial neural networks and SVR = support vector regression) are examined and used to predict the peak energy demand to estimate the energy usage for an office building on a university campus based on meteorological and historical energy data. Two-year energy and meteorological data are used, with one year for training and the following year for testing. To investigate the seasonal load trend and the prediction capabilities of the two approaches, two experiments are conducted relying on different scales of training data. In total, 10 prediction models are built, with 8 models implemented on seasonal training datasets and 2 models employed using year-round training data. It is observed that a backpropagation neural network (BPNN) performs better than SVR when dealing with more data, leading to stable generalization and low prediction error. When dealing with less data, it is found that there is no dominance of one approach over another.
{"title":"Predicting Peak Energy Demand for an Office Building Using Artificial Intelligence (AI) Approaches","authors":"Yuxuan Chen, P. Phelan","doi":"10.1115/power2021-64492","DOIUrl":"https://doi.org/10.1115/power2021-64492","url":null,"abstract":"\u0000 Due to the technological advancement in smart buildings and the smart grid, there is increasing desire of managing energy demand in buildings to achieve energy efficiency. In this context, building energy prediction has become an essential approach for measuring building energy performance, assessing energy system efficiency, and developing energy management strategies. In this study, two artificial intelligence techniques (i.e., ANN = artificial neural networks and SVR = support vector regression) are examined and used to predict the peak energy demand to estimate the energy usage for an office building on a university campus based on meteorological and historical energy data. Two-year energy and meteorological data are used, with one year for training and the following year for testing. To investigate the seasonal load trend and the prediction capabilities of the two approaches, two experiments are conducted relying on different scales of training data. In total, 10 prediction models are built, with 8 models implemented on seasonal training datasets and 2 models employed using year-round training data. It is observed that a backpropagation neural network (BPNN) performs better than SVR when dealing with more data, leading to stable generalization and low prediction error. When dealing with less data, it is found that there is no dominance of one approach over another.","PeriodicalId":8567,"journal":{"name":"ASME 2021 Power Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88054617","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}
Molecules’ characteristics of the active surface, such as low molecular weight fatty acids, asphaltene, and naphthenic acids determine the properties of emulsified fuels. They can interact with surfaces from other oils, water from liquid mixtures, solid surfaces from mechanical systems, or with pipes walls in case of long distances transport. For heavy oils which contain large amounts of asphaltene, these effects are very important. The characteristics of the emulsified fuels are determined mainly by the properties and nature of the emulsifier. In the present paper, some tests for heavy fuels emulsification with monoglycerides and cosurfactants are mentioned, due to their significant contributions in clean fuels combustion. This first proposed solution, presented in this paper is generally preferred, due to its small cost. The second tested solution consists in nonionic polymer obtained from the solid wastes of PET (polyethylene terephthalate) conversion and glycol. The main advantages of this raw material are the PET’s low cost and its large availability. The PET has high content of oxygen so the combustion of emulsified fuels with this type of surfactants assures low pollution emission. The preparation of the nonionic polymer associated with the glycerol recovery as additives for emulsified fuels is also mentioned. As the first stage, the PET transesterification with glycol at 200°C–210°C with ethylene glycol elimination was mentioned. For experiments, ten samples of emulsified fuels with different emulsifying agents were prepared, being tested their influence on fuel characteristics. Some physical properties of the emulsified fuel as the density at 20°C, viscosity at 90°C, flash point, and the freezing points were also determined. If the emulsifier proportion or the water quantity increase in the emulsified fuel the flash point increases also. Other experiments were realized referring to the freezing point and viscosity’s dependence with temperature. Finally, are presented some remarks concerning the proper report between emulsifier and final fuel properties.
{"title":"Influence of Some Emulsifiers in Improving the Biofuel Characteristics","authors":"V. Radulescu","doi":"10.1115/power2021-64223","DOIUrl":"https://doi.org/10.1115/power2021-64223","url":null,"abstract":"\u0000 Molecules’ characteristics of the active surface, such as low molecular weight fatty acids, asphaltene, and naphthenic acids determine the properties of emulsified fuels. They can interact with surfaces from other oils, water from liquid mixtures, solid surfaces from mechanical systems, or with pipes walls in case of long distances transport. For heavy oils which contain large amounts of asphaltene, these effects are very important. The characteristics of the emulsified fuels are determined mainly by the properties and nature of the emulsifier. In the present paper, some tests for heavy fuels emulsification with monoglycerides and cosurfactants are mentioned, due to their significant contributions in clean fuels combustion. This first proposed solution, presented in this paper is generally preferred, due to its small cost. The second tested solution consists in nonionic polymer obtained from the solid wastes of PET (polyethylene terephthalate) conversion and glycol. The main advantages of this raw material are the PET’s low cost and its large availability. The PET has high content of oxygen so the combustion of emulsified fuels with this type of surfactants assures low pollution emission. The preparation of the nonionic polymer associated with the glycerol recovery as additives for emulsified fuels is also mentioned. As the first stage, the PET transesterification with glycol at 200°C–210°C with ethylene glycol elimination was mentioned. For experiments, ten samples of emulsified fuels with different emulsifying agents were prepared, being tested their influence on fuel characteristics. Some physical properties of the emulsified fuel as the density at 20°C, viscosity at 90°C, flash point, and the freezing points were also determined. If the emulsifier proportion or the water quantity increase in the emulsified fuel the flash point increases also. Other experiments were realized referring to the freezing point and viscosity’s dependence with temperature. Finally, are presented some remarks concerning the proper report between emulsifier and final fuel properties.","PeriodicalId":8567,"journal":{"name":"ASME 2021 Power Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88038328","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}
Masis Torosyan, A. Pollman, A. Gannon, Alejandro S. Hernandez
This paper presents the results of an alternatives analysis of gas-liquefaction methods used in liquid air energy storage (LAES) systems that incorporates two novel measures of performance (MOP) into the analysis: system complexity score and system density. The cryogenic methods typically considered for air, and used in this trade study, include Linde-Hampson, Claude, Heylandt, and cascade [1]. With these four options of air-liquefaction currently in use for a variety of purposes with ranging scales, there exists no standard selection process for the air-liquefaction method in LAES. This trade study provides fundamental design solutions for given stakeholder requirements, allowing for a pragmatic analysis of integration for future implementation of LAES systems. The intent of these design solutions is to be used in the earliest stage of consideration of a LAES implementation, helping stakeholders quickly narrow the focus of their design engineers to a specific liquefaction process. This will reduce the complexity of integration techniques and processes and streamline LAES into the energy-storage industry. The results of this study showed that with evenly weighted MOP the Heylandt method had the highest final weighted score (0.9), followed by Cascade (0.88), Claude (0.86), and Linde-Hampson (0.67). However, the results showed that the Cascade method was the most frequent design solution (8/11) from 11 variations of MOP weight distributions.
{"title":"Performance and Complexity Trade Study of Candidate Liquid Air Generation Techniques","authors":"Masis Torosyan, A. Pollman, A. Gannon, Alejandro S. Hernandez","doi":"10.1115/power2021-63957","DOIUrl":"https://doi.org/10.1115/power2021-63957","url":null,"abstract":"\u0000 This paper presents the results of an alternatives analysis of gas-liquefaction methods used in liquid air energy storage (LAES) systems that incorporates two novel measures of performance (MOP) into the analysis: system complexity score and system density. The cryogenic methods typically considered for air, and used in this trade study, include Linde-Hampson, Claude, Heylandt, and cascade [1]. With these four options of air-liquefaction currently in use for a variety of purposes with ranging scales, there exists no standard selection process for the air-liquefaction method in LAES. This trade study provides fundamental design solutions for given stakeholder requirements, allowing for a pragmatic analysis of integration for future implementation of LAES systems. The intent of these design solutions is to be used in the earliest stage of consideration of a LAES implementation, helping stakeholders quickly narrow the focus of their design engineers to a specific liquefaction process. This will reduce the complexity of integration techniques and processes and streamline LAES into the energy-storage industry. The results of this study showed that with evenly weighted MOP the Heylandt method had the highest final weighted score (0.9), followed by Cascade (0.88), Claude (0.86), and Linde-Hampson (0.67). However, the results showed that the Cascade method was the most frequent design solution (8/11) from 11 variations of MOP weight distributions.","PeriodicalId":8567,"journal":{"name":"ASME 2021 Power Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87874894","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}
It is essential to secure energy sources by installing a private power generator for business continuity in a power outage. The authors have developed an optimization tool to estimate the optimal amount of distributed power supply equipment using economic efficiency and resilience as two evaluation indicators. However, it is questionable whether the private generator in a hospital building can generate sufficient electricity to meet demands in case of a power failure, because demand has short cycle fluctuations on the order of seconds, and the private generator must respond to these fluctuations from time to time in the case of stand-alone operation. The optimization tools we have developed in the past have not considered the balance between power output and load demand (demand sufficiency). Therefore, this paper proposes a new optimization method that considers balancing power supply and demand in private generators’ independent operation during power outages. We narrowed the optimization constraints as demand sufficiency conditions: standard AC frequency range between 49 and 51 Hz. More practical optimal solutions are obtained by applying the new constraints to the multi-optimization. We also compare the case study results by applying these constraints to the results of previous case studies.
{"title":"Optimization of the Capacities of Private Generators Installed in a Hospital Building Under the Constraint of Demand Sufficiency During Power Outages","authors":"A. Uemichi, Naoki Kaito, Y. Yamasaki, S. Kaneko","doi":"10.1115/power2021-62341","DOIUrl":"https://doi.org/10.1115/power2021-62341","url":null,"abstract":"\u0000 It is essential to secure energy sources by installing a private power generator for business continuity in a power outage. The authors have developed an optimization tool to estimate the optimal amount of distributed power supply equipment using economic efficiency and resilience as two evaluation indicators. However, it is questionable whether the private generator in a hospital building can generate sufficient electricity to meet demands in case of a power failure, because demand has short cycle fluctuations on the order of seconds, and the private generator must respond to these fluctuations from time to time in the case of stand-alone operation. The optimization tools we have developed in the past have not considered the balance between power output and load demand (demand sufficiency). Therefore, this paper proposes a new optimization method that considers balancing power supply and demand in private generators’ independent operation during power outages. We narrowed the optimization constraints as demand sufficiency conditions: standard AC frequency range between 49 and 51 Hz. More practical optimal solutions are obtained by applying the new constraints to the multi-optimization. We also compare the case study results by applying these constraints to the results of previous case studies.","PeriodicalId":8567,"journal":{"name":"ASME 2021 Power Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83459751","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}
Porous media are typically capable to enhance heat transfer, at the cost of an increase of the pressure drop, mainly in view of the huge increase in the surface wetted by the fluid. In this work, a tubular receiver for CSP applications, partly filled with a porous medium constituted by a packed bed of copper Raschig Rings is investigated for the first time. The analysis, carried out numerically, aims at studying in detail the mechanisms of the heat transfer from the wall to the gaseous heat transfer fluid (air) through the porous metal matrix in symmetric and asymmetric heating conditions. The computed results are compared to what occurs in a smooth tube subjected to the same heating, to check the increase in the heat transfer. The investigation carried out in this work represents the first step in the optimization of the porous medium structure inside the tubular receiver.
{"title":"First Numerical Evaluation of the Thermal Performance of a Tubular Receiver Equipped With Raschig Rings for CSP Applications","authors":"H. Ebadi, A. Allio, A. Cammi, L. Savoldi","doi":"10.1115/power2021-65714","DOIUrl":"https://doi.org/10.1115/power2021-65714","url":null,"abstract":"\u0000 Porous media are typically capable to enhance heat transfer, at the cost of an increase of the pressure drop, mainly in view of the huge increase in the surface wetted by the fluid. In this work, a tubular receiver for CSP applications, partly filled with a porous medium constituted by a packed bed of copper Raschig Rings is investigated for the first time. The analysis, carried out numerically, aims at studying in detail the mechanisms of the heat transfer from the wall to the gaseous heat transfer fluid (air) through the porous metal matrix in symmetric and asymmetric heating conditions. The computed results are compared to what occurs in a smooth tube subjected to the same heating, to check the increase in the heat transfer. The investigation carried out in this work represents the first step in the optimization of the porous medium structure inside the tubular receiver.","PeriodicalId":8567,"journal":{"name":"ASME 2021 Power Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89967001","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}
After constructing a scale model of planned changes to a power plant exhaust system, tests were performed to measure pressure losses in the transition, silencer, and stack. A dimension of 0.30 m (1.0 ft) for the scale model corresponded to 3.7 m (12.0 ft) at full scale. To the extent possible, the scale model tests exhibited geometric similarity with the actual power plant. Total pressure loss coefficients varied between 2.122, 1.969, and 1.932, for three separate scale model configurations that were considered. A combination of turning vanes and splitter vanes in the five-gore elbow, coupled with the use of turning vanes in the rectangular elbow yielded the lowest total pressure loss. Although Reynolds number similarity between the scale model experiments and the actual power plant was not attained, Reynolds number independence was achieved in the tests. The results from this study was applied to model pressure loss in the actual power plant. The scale model testing revealed that utilization of the exhaust ducting design designated as Case A would yield a sufficiently low pressure loss that it would not degrade the performance of the combustion turbine in the power plant to be repaired. Therefore it was selected for inclusion in the retro-fitting of the power plant to facilitate its being quickly brought back on-line.
{"title":"Combustion Turbine Exhaust Duct, Silencer, and Stack Scale Modeling","authors":"R. Craven, Keith Kirkpatrick, S. Idem","doi":"10.1115/power2021-64118","DOIUrl":"https://doi.org/10.1115/power2021-64118","url":null,"abstract":"\u0000 After constructing a scale model of planned changes to a power plant exhaust system, tests were performed to measure pressure losses in the transition, silencer, and stack. A dimension of 0.30 m (1.0 ft) for the scale model corresponded to 3.7 m (12.0 ft) at full scale. To the extent possible, the scale model tests exhibited geometric similarity with the actual power plant. Total pressure loss coefficients varied between 2.122, 1.969, and 1.932, for three separate scale model configurations that were considered. A combination of turning vanes and splitter vanes in the five-gore elbow, coupled with the use of turning vanes in the rectangular elbow yielded the lowest total pressure loss. Although Reynolds number similarity between the scale model experiments and the actual power plant was not attained, Reynolds number independence was achieved in the tests. The results from this study was applied to model pressure loss in the actual power plant. The scale model testing revealed that utilization of the exhaust ducting design designated as Case A would yield a sufficiently low pressure loss that it would not degrade the performance of the combustion turbine in the power plant to be repaired. Therefore it was selected for inclusion in the retro-fitting of the power plant to facilitate its being quickly brought back on-line.","PeriodicalId":8567,"journal":{"name":"ASME 2021 Power Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80599025","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 application of solar collectors in water heating systems has attracted attention in recent years, however, due to the inconsistency of solar radiation, performance of such systems will fluctuate over time. In this study, performance optimization of a heat pipe evacuated tube solar collector integrated with phase change materials (PCMs), is investigated under normal and on-demand operations. In phase-I, the effect of heat pipe position and in phase-II, the effect of various PCMs are investigated. The results from phase-I show phase change process of PCM was expedited by 48 minutes under on-demand operation compared with conventional system. Additionally, in normal operation, thermal storage enhancement is achieved by 24% increase in PCM’s melting fraction. In Phase-II, the selected PCMs are tritriacontane paraffin, xylitol, and erythritol. In normal mode, the paraffin tube exhibited highest total energy storage of 295.39 kJ/kg, however, the fin temperature of xylitol tube was around 10° C higher compared with the other tubes throughout the day. In on-demand operation, erythritol tube shows energy storage of 413.15 kJ/kg, however, the paraffin tube shows fin temperature difference of 14°C compared with other tubes. Consequently, utilization of paraffin/xylitol in normal and paraffin/erythritol in on-demand operation is recommended to enhance system’s thermal performance.
{"title":"Performance Optimization of Thermal Energy Storage Based Solar Collector","authors":"Vivek R. Pawar, Sarvenaz Sobhansarbandi","doi":"10.1115/power2021-64127","DOIUrl":"https://doi.org/10.1115/power2021-64127","url":null,"abstract":"\u0000 The application of solar collectors in water heating systems has attracted attention in recent years, however, due to the inconsistency of solar radiation, performance of such systems will fluctuate over time. In this study, performance optimization of a heat pipe evacuated tube solar collector integrated with phase change materials (PCMs), is investigated under normal and on-demand operations. In phase-I, the effect of heat pipe position and in phase-II, the effect of various PCMs are investigated. The results from phase-I show phase change process of PCM was expedited by 48 minutes under on-demand operation compared with conventional system. Additionally, in normal operation, thermal storage enhancement is achieved by 24% increase in PCM’s melting fraction. In Phase-II, the selected PCMs are tritriacontane paraffin, xylitol, and erythritol. In normal mode, the paraffin tube exhibited highest total energy storage of 295.39 kJ/kg, however, the fin temperature of xylitol tube was around 10° C higher compared with the other tubes throughout the day. In on-demand operation, erythritol tube shows energy storage of 413.15 kJ/kg, however, the paraffin tube shows fin temperature difference of 14°C compared with other tubes. Consequently, utilization of paraffin/xylitol in normal and paraffin/erythritol in on-demand operation is recommended to enhance system’s thermal performance.","PeriodicalId":8567,"journal":{"name":"ASME 2021 Power Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86974026","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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