Compressor operation under off-design conditions generates undesirable instabilities and detrimental effects both on system stability and machine reliability perspectives. The main objective is to provide a suitable approach and proper description of the flow and machine behaviour in the surge inception to reverse flow operating area, yielding valuable data for a deeper understanding of the underlying flow mechanisms, useful for tuning prediction models. A literature review, with a particular focus on the experimental method, test rig layout, and instrumentation when handling with reverse and pulsating flow, is presented. The need for a clear setting of test procedure and key parameters measurements to detect unsteady phenomena under transient conditions, with instrumentation available for field operation and separating compressor behaviour from system response, is specifically addressed. To perform this, the experimental technique is employed and described in detail in this paper, while performance modeling validation, object of parallel studies, will be presented in future publications. The test facility allows the required responsive dynamic measurements; tests cover a broad range of flow rates and two different rotational speeds. The aim is to specifically approach the instabilities sections and characterize the positive slope area, featuring rapid cycles between surge line and zero-flow. The results, presented as pressure and flow fluctuations, play a key role for the simulation of more complex dynamic scenarios. This wide collection of test data is of great value for a further understanding of the phenomenon, the development of reliable surge onset prediction models and control strategies.
{"title":"Experimental Characterization of Surge Cycles in a Centrifugal Compressor","authors":"A. Serena, L. Bakken","doi":"10.1115/imece2022-94747","DOIUrl":"https://doi.org/10.1115/imece2022-94747","url":null,"abstract":"\u0000 Compressor operation under off-design conditions generates undesirable instabilities and detrimental effects both on system stability and machine reliability perspectives.\u0000 The main objective is to provide a suitable approach and proper description of the flow and machine behaviour in the surge inception to reverse flow operating area, yielding valuable data for a deeper understanding of the underlying flow mechanisms, useful for tuning prediction models.\u0000 A literature review, with a particular focus on the experimental method, test rig layout, and instrumentation when handling with reverse and pulsating flow, is presented.\u0000 The need for a clear setting of test procedure and key parameters measurements to detect unsteady phenomena under transient conditions, with instrumentation available for field operation and separating compressor behaviour from system response, is specifically addressed. To perform this, the experimental technique is employed and described in detail in this paper, while performance modeling validation, object of parallel studies, will be presented in future publications.\u0000 The test facility allows the required responsive dynamic measurements; tests cover a broad range of flow rates and two different rotational speeds. The aim is to specifically approach the instabilities sections and characterize the positive slope area, featuring rapid cycles between surge line and zero-flow.\u0000 The results, presented as pressure and flow fluctuations, play a key role for the simulation of more complex dynamic scenarios. This wide collection of test data is of great value for a further understanding of the phenomenon, the development of reliable surge onset prediction models and control strategies.","PeriodicalId":292222,"journal":{"name":"Volume 8: Fluids Engineering; Heat Transfer and Thermal Engineering","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114238268","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}
Recent energy crisis has forced researchers to design fuel-efficient automobiles, where one of the main critical changes is to reduce aerodynamics drag created by fluid friction. At high speed, aerodynamics drag, especially the pressure drag, creates a substantial backward force, and hence, unwanted excess fuel is consumed to counterbalance this dragging effect, which hinders designing fuel-efficient automobiles. Hence, to mitigate this pressure drag, here in this work, numerical analyses have been done (i) to examine drag coefficient changes through incorporating aerodynamic vents at the front, at the rear, and both front and rear on the automobiles, (ii) to reduce drag force by utilizing exhaust gas to fill the low-pressure vortex, (iii) to investigate the effect of wheels on the overall drag resistance of the model. The ANSYS™ 2020 R1 Fluent module is used to perform this numerical simulation. Appreciable improvement on drag reduction can be found by incorporating above mentioned modifications on racing car body configuration.
{"title":"Numerical Investigation on Aerodynamic Performance of a Racing Car by Drag Reduction","authors":"M. Hassan, M. Hassan, Mohammad Ali, M. Amin","doi":"10.1115/imece2022-94495","DOIUrl":"https://doi.org/10.1115/imece2022-94495","url":null,"abstract":"\u0000 Recent energy crisis has forced researchers to design fuel-efficient automobiles, where one of the main critical changes is to reduce aerodynamics drag created by fluid friction. At high speed, aerodynamics drag, especially the pressure drag, creates a substantial backward force, and hence, unwanted excess fuel is consumed to counterbalance this dragging effect, which hinders designing fuel-efficient automobiles. Hence, to mitigate this pressure drag, here in this work, numerical analyses have been done (i) to examine drag coefficient changes through incorporating aerodynamic vents at the front, at the rear, and both front and rear on the automobiles, (ii) to reduce drag force by utilizing exhaust gas to fill the low-pressure vortex, (iii) to investigate the effect of wheels on the overall drag resistance of the model. The ANSYS™ 2020 R1 Fluent module is used to perform this numerical simulation. Appreciable improvement on drag reduction can be found by incorporating above mentioned modifications on racing car body configuration.","PeriodicalId":292222,"journal":{"name":"Volume 8: Fluids Engineering; Heat Transfer and Thermal Engineering","volume":"14 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131752203","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}
Ashutosh Pandey, Bharath Madduri, C. Perng, Chiranth Srinivasan, Sujan Dhar
Electric vehicles are becoming increasingly common due to environmental needs. Due to this, efficiency in design process of electric motors (E-motor) is becoming critical in the industry. To assess performance capabilities for an E-motor, thermal predictions are of utmost consequence. This study describes a computational method based on unsteady Reynolds-averaged Navier-Stokes equations that resolves the gas-liquid interface to examine the unsteady multiphase flow and heat transfer in a concentrated winding E-motor. The study considers all important parts of the motor i.e., coils, bobbins, stator laminate (yolk), rotor laminate, magnets etc. The study highlights the ease of capturing complex and intricate flow paths with a robust mesh generation tool in combination with a robust high-fidelity interface capturing VOF scheme to resolve the gas-liquid interfaces. Results obtained show the dominant processes that determine the oil distribution to be the centrifugal force from rotation of the rotor, the flow rate of oil injected in the stator assembly as well as in the rotor assembly and gravity. A novel heat transfer approach (mixed time-scale coupling) is used to solve for the temperatures in the stator and rotor solids. The approach first requires achieving a quasi-steady flow solution before initiating heat transfer calculation for faster turnaround times. The approach separates the conjugate heat transfer calculation into a fluid heat simulation and a solid heat simulation while setting up a communication method to exchange the thermal boundary conditions between the two simulations. This study also considers the anisotropic nature of thermal conductivities resulting from the wound-around arrangement of the coils and the laminate nature of stator/rotor laminates in the assignment of the thermal conductivities of these solids. Results of thermal simulation show the solid temperatures to be in direct correlation with the oil distribution near those solids. This computational study was validated by comparing the computed and measured temperatures at specified locations on the coils and good agreements with experiments were found.
{"title":"Multiphase Flow and Heat Transfer in an Electric Motor","authors":"Ashutosh Pandey, Bharath Madduri, C. Perng, Chiranth Srinivasan, Sujan Dhar","doi":"10.1115/imece2022-96801","DOIUrl":"https://doi.org/10.1115/imece2022-96801","url":null,"abstract":"\u0000 Electric vehicles are becoming increasingly common due to environmental needs. Due to this, efficiency in design process of electric motors (E-motor) is becoming critical in the industry. To assess performance capabilities for an E-motor, thermal predictions are of utmost consequence. This study describes a computational method based on unsteady Reynolds-averaged Navier-Stokes equations that resolves the gas-liquid interface to examine the unsteady multiphase flow and heat transfer in a concentrated winding E-motor. The study considers all important parts of the motor i.e., coils, bobbins, stator laminate (yolk), rotor laminate, magnets etc. The study highlights the ease of capturing complex and intricate flow paths with a robust mesh generation tool in combination with a robust high-fidelity interface capturing VOF scheme to resolve the gas-liquid interfaces. Results obtained show the dominant processes that determine the oil distribution to be the centrifugal force from rotation of the rotor, the flow rate of oil injected in the stator assembly as well as in the rotor assembly and gravity. A novel heat transfer approach (mixed time-scale coupling) is used to solve for the temperatures in the stator and rotor solids. The approach first requires achieving a quasi-steady flow solution before initiating heat transfer calculation for faster turnaround times. The approach separates the conjugate heat transfer calculation into a fluid heat simulation and a solid heat simulation while setting up a communication method to exchange the thermal boundary conditions between the two simulations. This study also considers the anisotropic nature of thermal conductivities resulting from the wound-around arrangement of the coils and the laminate nature of stator/rotor laminates in the assignment of the thermal conductivities of these solids. Results of thermal simulation show the solid temperatures to be in direct correlation with the oil distribution near those solids. This computational study was validated by comparing the computed and measured temperatures at specified locations on the coils and good agreements with experiments were found.","PeriodicalId":292222,"journal":{"name":"Volume 8: Fluids Engineering; Heat Transfer and Thermal Engineering","volume":"70 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132348884","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 fossil fuel depletion and environmental pollution are global challenges. Hydrogen is one of the most abundant elements on earth. Recently, scientists and researchers are investigating water splitting to produce oxy-hydrogen for internal combustion engines. Several studies have been published where hydrogen was used to generate electricity. The proton exchange membrane fuel cell (PEMFC) is an alternative energy resource for future electric vehicles. The reaction of PEMFC includes hydrogen molecules splitting as hydrogen ions and electrons on the anode whereas proton meet with oxygen and electrons and form water and release heat on the cathode. There are several processes involved in heat generation in PEMFC such as resistance in current flow, entropic heat reaction, and irreversibility of the electrochemical reactions. The generated heat in PEMFC is removed through cooling channels. The heat transfer rate depends on thermal properties. The design of the such as polymer electrolyte membrane, catalyst layer, gas diffusion layer, and electrodes have different thermal properties which influence heat transfer. Proper thermal management is critical part of PEMFC operation. Because the efficiency of PEMFC depends on heat loss in-between critical range. In this study, a numerical approach is used to investigate heat transfer performance of a (PEMFC) cooling channel. The heat transfer rate, convective heat transfer coefficient, temperature distribution and pressure drop were evaluated in this work. All these results were carried out on, 0.2, 0.4, 0.6 0.8 and 1 kg/s of mass flow rate of coolant in the PEMFC cooling channel. Ansys Fluent is used for the numerical investigation. The diamond shape extended staggered pattern cooling channel were used in fuel cell for distributed flow. In this study, 2mm transverse pitch whereas 1mm, 1.5 mm and 2 mm longitudinal pitch with diamond shape extended in PEMFC cooling channel are used. However, design of experiments method was used to sort optimum results. The results reveal the extended staggered cooling channel improve heat transfer performance, 2mm and 1.5 mm transverse and longitudinal pitch respectively gave better heat transfer results and slightly higher pressure drops than 2mm pitch. Turbulence kinetic increases with decreasing transverse pitch and flow distribution improved with longitudinal pitch.
{"title":"Heat Transfer Performance Evaluation of PEMFC With Diamond-Shaped Staggered Cooling Channel","authors":"Pirbux Mughal, Yadong He, Ramzan Luhur","doi":"10.1115/imece2022-95589","DOIUrl":"https://doi.org/10.1115/imece2022-95589","url":null,"abstract":"\u0000 The fossil fuel depletion and environmental pollution are global challenges. Hydrogen is one of the most abundant elements on earth. Recently, scientists and researchers are investigating water splitting to produce oxy-hydrogen for internal combustion engines. Several studies have been published where hydrogen was used to generate electricity. The proton exchange membrane fuel cell (PEMFC) is an alternative energy resource for future electric vehicles. The reaction of PEMFC includes hydrogen molecules splitting as hydrogen ions and electrons on the anode whereas proton meet with oxygen and electrons and form water and release heat on the cathode. There are several processes involved in heat generation in PEMFC such as resistance in current flow, entropic heat reaction, and irreversibility of the electrochemical reactions. The generated heat in PEMFC is removed through cooling channels. The heat transfer rate depends on thermal properties. The design of the such as polymer electrolyte membrane, catalyst layer, gas diffusion layer, and electrodes have different thermal properties which influence heat transfer. Proper thermal management is critical part of PEMFC operation. Because the efficiency of PEMFC depends on heat loss in-between critical range. In this study, a numerical approach is used to investigate heat transfer performance of a (PEMFC) cooling channel. The heat transfer rate, convective heat transfer coefficient, temperature distribution and pressure drop were evaluated in this work. All these results were carried out on, 0.2, 0.4, 0.6 0.8 and 1 kg/s of mass flow rate of coolant in the PEMFC cooling channel. Ansys Fluent is used for the numerical investigation. The diamond shape extended staggered pattern cooling channel were used in fuel cell for distributed flow. In this study, 2mm transverse pitch whereas 1mm, 1.5 mm and 2 mm longitudinal pitch with diamond shape extended in PEMFC cooling channel are used. However, design of experiments method was used to sort optimum results. The results reveal the extended staggered cooling channel improve heat transfer performance, 2mm and 1.5 mm transverse and longitudinal pitch respectively gave better heat transfer results and slightly higher pressure drops than 2mm pitch. Turbulence kinetic increases with decreasing transverse pitch and flow distribution improved with longitudinal pitch.","PeriodicalId":292222,"journal":{"name":"Volume 8: Fluids Engineering; Heat Transfer and Thermal Engineering","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121256310","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}
Inês Gonçalves, J. Marques, J. Silva, J. Teixeira, F. Alvelos, T. Tavares, S. Teixeira
Wildfires are a worldwide phenomenon that as an impact on all surrounding forms of life. Studying these events is essential to develop and optimize the tools used for combat and prevention, and its behavior is associated with the state of the vegetation, atmospheric conditions, ground properties, and many others, constituting an expensive and challenging task. This work presents itself as a complementary work to study the flow over a forest through a CFD model, which causes a modification in the velocity profile due to the drag produced by the forest presence, and the values obtained can be used in a mathematical model to study the fire rate of spread and fireline intensity considering the new velocity field. The CFD model was applied in the commercial software Ansys Fluent. The results confirmed that the wind is a dominant force during a forest fire, i.e., at high velocities the fire has an aggressive behavior and at low velocities tends to calm down. However, due to the unpredictability of certain weather conditions, it is dangerous to say that a forest fire is fully controlled since its behavior can change in a matter of minutes.
{"title":"Development of CFD Model to Study the Spread of Wildfires","authors":"Inês Gonçalves, J. Marques, J. Silva, J. Teixeira, F. Alvelos, T. Tavares, S. Teixeira","doi":"10.1115/imece2022-95980","DOIUrl":"https://doi.org/10.1115/imece2022-95980","url":null,"abstract":"\u0000 Wildfires are a worldwide phenomenon that as an impact on all surrounding forms of life. Studying these events is essential to develop and optimize the tools used for combat and prevention, and its behavior is associated with the state of the vegetation, atmospheric conditions, ground properties, and many others, constituting an expensive and challenging task.\u0000 This work presents itself as a complementary work to study the flow over a forest through a CFD model, which causes a modification in the velocity profile due to the drag produced by the forest presence, and the values obtained can be used in a mathematical model to study the fire rate of spread and fireline intensity considering the new velocity field. The CFD model was applied in the commercial software Ansys Fluent.\u0000 The results confirmed that the wind is a dominant force during a forest fire, i.e., at high velocities the fire has an aggressive behavior and at low velocities tends to calm down. However, due to the unpredictability of certain weather conditions, it is dangerous to say that a forest fire is fully controlled since its behavior can change in a matter of minutes.","PeriodicalId":292222,"journal":{"name":"Volume 8: Fluids Engineering; Heat Transfer and Thermal Engineering","volume":"180 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124492880","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}
A relatively low specific speed dry pit solids handling pump was designed from scratch with pure 3D CFD virtual testing. In-house codes were used to provide preliminary design of the impeller, volute, etc. The 3D CFD tool Simerics-MP+ was employed for improvement of the design to achieve the desired pump performance. The virtual tests covered a wide range of flowrates from 40% to 130% of the best efficiency point (BEP). Final physical testing shows the CFD predictions are in good agreement with the measurements.
{"title":"Design a Low Specific Speed Dry Pit Solids Handling Pump With Pure 3-D Computational Fluid Dynamics Virtual Testing","authors":"Azfar Ali, Zhuoyu Zhou","doi":"10.1115/imece2022-94551","DOIUrl":"https://doi.org/10.1115/imece2022-94551","url":null,"abstract":"\u0000 A relatively low specific speed dry pit solids handling pump was designed from scratch with pure 3D CFD virtual testing. In-house codes were used to provide preliminary design of the impeller, volute, etc. The 3D CFD tool Simerics-MP+ was employed for improvement of the design to achieve the desired pump performance. The virtual tests covered a wide range of flowrates from 40% to 130% of the best efficiency point (BEP). Final physical testing shows the CFD predictions are in good agreement with the measurements.","PeriodicalId":292222,"journal":{"name":"Volume 8: Fluids Engineering; Heat Transfer and Thermal Engineering","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124962871","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}
Commercial thermal desalination plants usually leverage static flash evaporation and vapor separation processes that occur separately in large chambers. Depending on the level of purity — the product can be used for potable water (for human consumption), for agriculture or ranching, or as input for industrial processes (such as in injection wells in oil and gas production operations). Currently, static methods such as Multi Stage Flash (MSF) or Multi Effect Distillation (MED) are widely used (in addition to Reverse Osmosis) for desalination. These static methods occupy large land area (large footprint). This in turn drives up the capital and production costs of the resulting purified water obtained in these techniques. Desalination processes that leverage evaporation and vapor separation in the same chamber (dynamically) have smaller form factors which confers lower cost of desalination. Thus, the motivation of our study is to develop a novel apparatus to simultaneously generate vapor by flash evaporation and separate the produced vapor in the same apparatus. The novel apparatus is geared for desalination of sea water, remediation of produced water from process-industries and other sources of saline water (such as brackish water) that are deemed unfit for human consumption. The end goal of the project is to develop a solar-thermal desalination platform by leveraging hot saline water as input from solar ponds. In this experimental study, the thermal-hydraulic performance of a prototype (lab-scale) dynamic vapor generation and swirl flow phase separation apparatus is explored for determining the efficacy of this novel concept. Heated water from a constant temperature supply tank (that is comparable to a solar pond in real life) is passed through injection passages into the flow-separation apparatus. As the water flows through the injection passages, vapor bubbles are generated inside the flow passages due to local superheating of the liquid caused by frictional pressure drop. Conversion of liquid into vapor continues as the liquid-vapor mixture flows through the injector ports and eventually the mixture enters a larger separation tube tangentially. Due to the tangential injection of the two-phase mixture, a centrifugal force acts to separate the water and vapor inside the separation tube. The liquid is pushed to the periphery (i.e., the walls) of the separation tube while the vapor forms a stable core at the center. A vapor retrieval tube is then positioned at the center of the vapor core to extract vapor which is then condensed inside the condenser. The formation of the vapor core is demonstrated for different operating conditions (supply liquid flow rates) and maximum superheat (temperature difference between supply tank and condenser) ranging between 45–52°C. Based on this study, the optimal operating conditions for maximizing the thermal conversion upstream of the test section are presented.
{"title":"Experimental Investigation of Solar-Thermal Desalination Platform Leveraging Dynamic Flash Evaporation and Swirl Flow Separator","authors":"A. Thyagarajan, V. Dhir, D. Banerjee","doi":"10.1115/imece2022-96099","DOIUrl":"https://doi.org/10.1115/imece2022-96099","url":null,"abstract":"\u0000 Commercial thermal desalination plants usually leverage static flash evaporation and vapor separation processes that occur separately in large chambers. Depending on the level of purity — the product can be used for potable water (for human consumption), for agriculture or ranching, or as input for industrial processes (such as in injection wells in oil and gas production operations). Currently, static methods such as Multi Stage Flash (MSF) or Multi Effect Distillation (MED) are widely used (in addition to Reverse Osmosis) for desalination. These static methods occupy large land area (large footprint). This in turn drives up the capital and production costs of the resulting purified water obtained in these techniques.\u0000 Desalination processes that leverage evaporation and vapor separation in the same chamber (dynamically) have smaller form factors which confers lower cost of desalination. Thus, the motivation of our study is to develop a novel apparatus to simultaneously generate vapor by flash evaporation and separate the produced vapor in the same apparatus. The novel apparatus is geared for desalination of sea water, remediation of produced water from process-industries and other sources of saline water (such as brackish water) that are deemed unfit for human consumption. The end goal of the project is to develop a solar-thermal desalination platform by leveraging hot saline water as input from solar ponds.\u0000 In this experimental study, the thermal-hydraulic performance of a prototype (lab-scale) dynamic vapor generation and swirl flow phase separation apparatus is explored for determining the efficacy of this novel concept. Heated water from a constant temperature supply tank (that is comparable to a solar pond in real life) is passed through injection passages into the flow-separation apparatus. As the water flows through the injection passages, vapor bubbles are generated inside the flow passages due to local superheating of the liquid caused by frictional pressure drop. Conversion of liquid into vapor continues as the liquid-vapor mixture flows through the injector ports and eventually the mixture enters a larger separation tube tangentially. Due to the tangential injection of the two-phase mixture, a centrifugal force acts to separate the water and vapor inside the separation tube. The liquid is pushed to the periphery (i.e., the walls) of the separation tube while the vapor forms a stable core at the center. A vapor retrieval tube is then positioned at the center of the vapor core to extract vapor which is then condensed inside the condenser.\u0000 The formation of the vapor core is demonstrated for different operating conditions (supply liquid flow rates) and maximum superheat (temperature difference between supply tank and condenser) ranging between 45–52°C. Based on this study, the optimal operating conditions for maximizing the thermal conversion upstream of the test section are presented.","PeriodicalId":292222,"journal":{"name":"Volume 8: Fluids Engineering; Heat Transfer and Thermal Engineering","volume":"181 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122080623","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}
Small Modular Reactors (SMRs) are promising to address a wide range of energy needs. Steam generator (SG) is usually one of the largest and most expensive components in a nuclear energy system. Therefore, the overall economics of an SMR plant employing a steam Rankine cycle is strongly influenced by its SG selection. Previous case studies conducted at the Idaho National Laboratory, assessing the techno-economic performance of advanced reactors for water desalination and hydrogen production, have mostly focused on reactor system options with conventional U-tube SGs or helical-coil SGs. Incorporating a two-phase Printed Circuit Heat Exchanger (PCHE) as a SG, termed a Printed Circuit Steam Generator (PCSG), has the potential to further improve the plant economics by significantly reducing the system volume through its enhanced compactness. This paper summarizes an ongoing effort to access the thermal-hydraulic performance of a PCSG for SMRs and establishes a reference model using the correlations that have been adopted and benchmarked by the latest PCSG modeling study. Our results suggest that using a one-dimensional (1-D) code for outlet temperature calculations (i.e., the hot and cold sides) and a pressure drop calculation for the single-phase flow (i.e., the hot side) can be as accurate as those in the three-dimensional (3-D) code used in Ocampo’s study in 2020 (typically less than 0.5 % and 7 % differences, respectively). However, it is noted that the calculated pressure drop for the cold side shows as high as 4 % and 25 % of discrepancies between the correlations and the dimension of simulation (i.e., 1-D and 3-D), respectively. The identified ranges of the uncertainties from this inter-model comparison would support the development of PCSG designs for SMRs while urging researchers to develop validated thermal-hydraulic models for PCSG.
{"title":"Review of Thermal-Hydraulic Modeling Methods of Printed Circuit Steam Generators for Small Modular Reactors","authors":"So-Bin Cho, Chengqi Wang, T. Allen, Xiaodong Sun","doi":"10.1115/imece2022-96578","DOIUrl":"https://doi.org/10.1115/imece2022-96578","url":null,"abstract":"\u0000 Small Modular Reactors (SMRs) are promising to address a wide range of energy needs. Steam generator (SG) is usually one of the largest and most expensive components in a nuclear energy system. Therefore, the overall economics of an SMR plant employing a steam Rankine cycle is strongly influenced by its SG selection. Previous case studies conducted at the Idaho National Laboratory, assessing the techno-economic performance of advanced reactors for water desalination and hydrogen production, have mostly focused on reactor system options with conventional U-tube SGs or helical-coil SGs. Incorporating a two-phase Printed Circuit Heat Exchanger (PCHE) as a SG, termed a Printed Circuit Steam Generator (PCSG), has the potential to further improve the plant economics by significantly reducing the system volume through its enhanced compactness. This paper summarizes an ongoing effort to access the thermal-hydraulic performance of a PCSG for SMRs and establishes a reference model using the correlations that have been adopted and benchmarked by the latest PCSG modeling study. Our results suggest that using a one-dimensional (1-D) code for outlet temperature calculations (i.e., the hot and cold sides) and a pressure drop calculation for the single-phase flow (i.e., the hot side) can be as accurate as those in the three-dimensional (3-D) code used in Ocampo’s study in 2020 (typically less than 0.5 % and 7 % differences, respectively). However, it is noted that the calculated pressure drop for the cold side shows as high as 4 % and 25 % of discrepancies between the correlations and the dimension of simulation (i.e., 1-D and 3-D), respectively. The identified ranges of the uncertainties from this inter-model comparison would support the development of PCSG designs for SMRs while urging researchers to develop validated thermal-hydraulic models for PCSG.","PeriodicalId":292222,"journal":{"name":"Volume 8: Fluids Engineering; Heat Transfer and Thermal Engineering","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128042473","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}
Pipeline monitoring and leak detection are critical for safe and economical operation as well as preventative maintenance in water and oil industry. They also provide environmental protection from crude oil emission or theft. Leak detection and localization play a key role in the overall integrity monitoring of a pipeline system especially for long residential water pipelines and midstream crude pipelines. Operational data such as fluid flow and pressure data are often utilized in many physics and computation-based leak detection and localization methods. However, noise in both flow and pressure affects recognition of actual leak pressure drop and results in false leak alarm and inaccurate leakage localization. In this paper a total variation regularized numerical differentiation (TVRegDiff) algorithm is used to estimate derivatives from noisy fluid flow and pressure data. Then possible leak events from both fluid flow data and pressure data are obtained by examining these derivatives against corresponding control limit lines. Customized parameter criteria of flow and operation activities are used to effectively filter flow and operation events from possible leak events. Therefore, earliest leak occurrence time and pressure meters can be identified. Finally, negative pressure wave (NPW) analysis is combined with the leak recognition to compute and locate leakage. Negative pressure wave methods are based on the principle that a leak will cause a sudden pressure alteration as well as a decrease in fluid flow speed which will result in an instantaneous pressure drop and speed variation along the pipeline. As the instantaneous pressure drop occurs, it generates a negative pressure wave starting at the leakage position and propagates with certain speeds towards both the upstream and downstream ends of the pipeline section. Depending on the leakage position from the two ends and actual negative pressure wave velocities towards upstream and downstream there are time sequence of the pressure wave arriving at both ends. The lapse of time arrival and negative pressure wave velocities are then used to calculate the actual leakage position within the pipeline section. A field leak case study indicates that actual leak pressure drop is correctly captured and pipeline leakage can be accurately located. The accuracy of leak localization is theoretically dependent on the pressure and flow meter frequency. With widely accepted industry standards for pressure devices used in industry applications it is proved to be a practical, efficient and accurate leak detection and localization method. This method can also be applied to not only residential water pipelines but crude oil pipelines.
{"title":"Pipeline Leak Detection and Localization Based on Advanced Signal Processing and Negative Pressure Wave Analysis","authors":"Weiming Li","doi":"10.1115/imece2022-95048","DOIUrl":"https://doi.org/10.1115/imece2022-95048","url":null,"abstract":"\u0000 Pipeline monitoring and leak detection are critical for safe and economical operation as well as preventative maintenance in water and oil industry. They also provide environmental protection from crude oil emission or theft. Leak detection and localization play a key role in the overall integrity monitoring of a pipeline system especially for long residential water pipelines and midstream crude pipelines. Operational data such as fluid flow and pressure data are often utilized in many physics and computation-based leak detection and localization methods. However, noise in both flow and pressure affects recognition of actual leak pressure drop and results in false leak alarm and inaccurate leakage localization. In this paper a total variation regularized numerical differentiation (TVRegDiff) algorithm is used to estimate derivatives from noisy fluid flow and pressure data. Then possible leak events from both fluid flow data and pressure data are obtained by examining these derivatives against corresponding control limit lines. Customized parameter criteria of flow and operation activities are used to effectively filter flow and operation events from possible leak events. Therefore, earliest leak occurrence time and pressure meters can be identified. Finally, negative pressure wave (NPW) analysis is combined with the leak recognition to compute and locate leakage. Negative pressure wave methods are based on the principle that a leak will cause a sudden pressure alteration as well as a decrease in fluid flow speed which will result in an instantaneous pressure drop and speed variation along the pipeline. As the instantaneous pressure drop occurs, it generates a negative pressure wave starting at the leakage position and propagates with certain speeds towards both the upstream and downstream ends of the pipeline section. Depending on the leakage position from the two ends and actual negative pressure wave velocities towards upstream and downstream there are time sequence of the pressure wave arriving at both ends. The lapse of time arrival and negative pressure wave velocities are then used to calculate the actual leakage position within the pipeline section. A field leak case study indicates that actual leak pressure drop is correctly captured and pipeline leakage can be accurately located. The accuracy of leak localization is theoretically dependent on the pressure and flow meter frequency. With widely accepted industry standards for pressure devices used in industry applications it is proved to be a practical, efficient and accurate leak detection and localization method. This method can also be applied to not only residential water pipelines but crude oil pipelines.","PeriodicalId":292222,"journal":{"name":"Volume 8: Fluids Engineering; Heat Transfer and Thermal Engineering","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128165243","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}
A photonic-based nanohole array sensor microcalorimetry is developed at the Microfluidic laboratory at Northeastern University utilizing changes in the extraordinary optical transmission (EOT). This experiment utilized calorimetry to conduct a novel specific heat measurement method for non-reacting fluids on the microscale level. This paper describes a calibration process and an accuracy test for this novel calorimetry. The test chamber was prefilled with deionized (DI) water (55 μl) and heated to steady state. Then room temperature DI water (15 μl) was injected and was treated as an unknown material. The temperature time history is recorded by the thermistor data acquisition system and the EOT by a CCD camera. An energy balance equation and algorithm were developed to calculate the specific heat of the injected material which was compared with its known value. The observed EOT and the corresponding temperature calculated from it exhibit the same trends. The error between the measured and known specific heat specific is 2–6%. The calorimetry has a significantly faster thermal response than traditional calorimeters and requires less compound with high accuracy.
{"title":"Operational Performance of a Photonic Based Microcalorimeter: Specific Heat Measurement","authors":"Yuwei Zhang, G. Kowalski","doi":"10.1115/imece2022-95148","DOIUrl":"https://doi.org/10.1115/imece2022-95148","url":null,"abstract":"\u0000 A photonic-based nanohole array sensor microcalorimetry is developed at the Microfluidic laboratory at Northeastern University utilizing changes in the extraordinary optical transmission (EOT). This experiment utilized calorimetry to conduct a novel specific heat measurement method for non-reacting fluids on the microscale level. This paper describes a calibration process and an accuracy test for this novel calorimetry. The test chamber was prefilled with deionized (DI) water (55 μl) and heated to steady state. Then room temperature DI water (15 μl) was injected and was treated as an unknown material. The temperature time history is recorded by the thermistor data acquisition system and the EOT by a CCD camera. An energy balance equation and algorithm were developed to calculate the specific heat of the injected material which was compared with its known value. The observed EOT and the corresponding temperature calculated from it exhibit the same trends. The error between the measured and known specific heat specific is 2–6%. The calorimetry has a significantly faster thermal response than traditional calorimeters and requires less compound with high accuracy.","PeriodicalId":292222,"journal":{"name":"Volume 8: Fluids Engineering; Heat Transfer and Thermal Engineering","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129135729","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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