Fluid Thermodynamics Research Articles

Thermodynamic analysis of zinc ferrite (ZnFe2O4) formation inside the HIsarna off-gas system

ABSTRACT HIsarna reactor is characterized by a high raw materials versatility and is therefore attractive for processing secondary iron sources. Among the materials that can be recycled through HIsarna, zinc-bearing material has drawn a special attention. Based on the plant data, once dust-containing Zinc was injected into the main reactor, a final collected dust with a zinc content of 16% was achieved which opened up possibilities of higher enrichment for direct reuse in Zn smelting as a secondary source and an alternative for Zn ore (the primary source). However Zn vapor can react with iron oxide to form zinc ferrite (ZnFe2O4), which is an undesired product. Hence, the main focus of this study is to minimize the formation of ZnFe2O using thermodynamic (FactSage) and computational fluid dynamic tools. After detecting regions with high potential of ZnFe2O4 formation, proper geometrical and operational modifications of the off-gas system is proposed to minimize the formation of zinc ferrite.

Thermodynamic–Dynamic Interrelations in Glass-Forming Polymer Fluids

We utilize the lattice cluster theory (LCT) of polymer fluids to show that the configurational entropy, enthalpy, and internal energy are all closely interrelated, as suggested by recent measurements by Caruthers and Medvedev, so that the generalized entropy theory (GET) of glass formation, a combination of the LCT and Adam-Gibbs model, can be recast in terms of any of these thermodynamic properties as a matter of convenience. Thermodynamic scaling, a form of density-temperature scaling exhibited by dynamic and some thermodynamic properties, is used to assess which thermodynamic properties are most naturally linked to dynamics, and we explore the origin of this scaling by both direct calculations based on the GET and molecular dynamics simulations of a coarse-grained polymer model. Through a combination of our comprehensive modeling of thermodynamic properties using the LCT and the highly predictive GET model for how the fluid thermodynamics relate to its dynamics, along with simulation results confirming these theoretical frameworks, we obtain insights into thermodynamic aspects of collective motion and the slow $\beta$-relaxation processes of glass-forming liquids.

SIMULATION OF NATURAL GAS INFRASTRUCTURE FOR CNG AND LPG RECOVERY - A CASE STUDY

This research is a case study focused at presenting a framework upon which design methods can be followed to achieve an effective natural gas gathering, processing and fractionation process. It also reveals the incentive for flare reduction while encouraging domestic consumption of Liquefied Petroleum Gas (LPG) and the use of Compressed Natural Gas (CNG) for electricity generation. The simulation of the plant was done using ASPEN HYSYS version 11.0 with the Peng Robinson equation of state as the thermodynamic fluid package. The gas was gathered from two flow stations 0.8km and 6.4km respectively from the proposed processing field. Since the gases from the region under study is a sweet with negligible sulphur content there was no need for a sweetening process. The Tri-Ethylene Glycol (TEG) was used for the gas dehydration, then fractionators were simulated to produce LPG and CNG of high purity. Results from the HYSYS report shows good energy and mass balance as well as efficient gas flow throughout the processing cycle. The resulting volume of CNG and LPG is substantial to power several households and supply them with cooking gas respectively. Keywords: Natural Gas Simulation, Liquefied Petroleum Gas, Compressed Natural Gas, Computer aided Design.

Conceptual design of an innovative gas–gas ceramic compact heat exchanger suitable for high temperature applications

The development of an innovative and highly efficient heat exchanger (HE) solution for gas–gas heat recovery is one of the major objectives of the HYDROSOL-beyond project which aims at enhancing the process efficiency for producing hydrogen from water dissociation with concentrated sunlight. Because of the very high temperature level of the process (up to 1400 °C), an innovative ceramic HE design was proposed with an integrated lattice structure, as secondary surface, to maximize the heat transfer. To assist the design of the HE, a multiscale approach was adopted: a 1D model based on global correlations was developed and a 3D computational fluid dynamics model of the secondary surfaces were generated. The former was applied to assess the performance of the entire HE; while, the latter was exploited to study in detail the thermo-fluid dynamics behavior of a HE core element and to provide the global correlations to be integrated into the 1D model. In this work, the effect of several parameters and operating conditions, namely, number of channels, number of lattice layers located into each channel, solid material exploited for the HE structure, parting plates thickness, heat transfer fluid velocity, radiation heat transfer and solid material emissivity, on the HE effectiveness are reported and accurately described. Furthermore, based upon the results obtained, guidelines on the HE design to maximize its performance are also provided.

Examination of Students’ Academic Performance in Selected Mechanical Engineering Courses Prior-to-and-During COVID-19 Era

Advances in Information and Communications Technology (ICT) as well as the present challenges of COVID-19 have led to a new paradigm causing an absolute or partial transition from in-person classroom teaching-learning to online. There is little information available on research efforts that investigated the impact of an online learning approach on the academic performance of students in mechanical engineering-based courses. Therefore, the objective of this paper is the impact study of online learning mode as compared to in-person on academic performance of students in selected mechanical engineering courses in one of the Universities in South Pacific Islands prior-to-and-during COVID-19 Era. Data on grades obtained for 178 students that offered Fluid Mechanics, Thermodynamics, Heat Transfer, and Advanced Thermofluids (FTHA) courses were subjected to descriptive and non-parametric (Mann-Whitney and Kruskal-Wallis) statistical tests. Although descriptive analysis showed that online mode of instruction might influence a better academic performance in FTHA courses in comparison with in-person mode of instruction, the outcome of Mann-Whitney U and Kruskal-Wallis tests at specific p-values and corresponding z-values generally exhibited p-values higher than of 0.05, implying insignificant difference in performance between the two modes of learning investigated. Though the non-parametric statistical test results showed there was no significant difference in academic performance of students when online and in-person modes of learning were used, this, however, does not imply that a difference does not exist at all. Although the difference may be very trivial, descriptive analysis has shown that the online learning mode has at least exhibited better students’ academic performance when compared to in-person. It can be inferred from the foregoing that the online learning mode does not yield a negative response in respect of the performance of students who offered all four mechanical engineering courses. Based on the findings of this study, online is considered a reliable alternative to in-person or at least a suitable complement to in-person in the in-person-online hybrid mode during the ongoing COVID-19 era and other inevitable constraints in the future. Doi: 10.28991/esj-2022-SPER-017 Full Text: PDF

Viscoelastic and Viscoplastic Glucose Theory (VGT #29): Applying viscoelastic Glucose Theory with CGM Sensor Measured Fasting Plasma Glucose (FPG) Values as the Strain along with the FPG Change Rate Multiplied by a Viscosity Factor as the Stress, and Finally Utilizing the Viscoelastic Perturbation Model to Calculate the Predicted FPG Values to Compare Against the Measured FPG Values Based on GH-Method:

The author has studied strength of materials and theory of elasticity through his undergraduate courses at the University of Iowa. He also conducted research work to earn a master’s degree in Biomechanics under Professor James Andrews. At that time, he used the spring and dashpot models to simulate the behaviors of human joints, bones, muscles, and tendons in order to investigate the human-weapon interactions during the Vietnam war era. Later, he went to MIT to pursue his PhD study under Professor Norman Jones, who taught him theory of plasticity and dynamic plastic behaviors of various structure elements. He also took additional graduate courses in the field of fluid dynamics and thermodynamics. Since then, many advancements have been made in the biomechanics branch, especially with human body tissues that possess certain viscoelastic characteristics, such as bones, muscles, cartilages, tendons (connect bone to muscle), ligaments (connect bone to bone), fascia, and skin. For example, the author suffered plantar fasciitis for many years. He understood that the night splint dorsiflexes forefoot, at the back of the foot, increases plantar fascia tension to offer stress-relaxation for the pain. This model where muscles and tendons connect the lower leg and foot is a form of viscoelastic study for medical problem solving. When dealing with human internal organs, it is not easy to conduct live experiments to obtain accurate measurements for the biomedical material properties. Blood itself is a viscous material (time-dependent) and its viscosity factor may fall between water, honey, syrup, or gel. The author’s research focuses on “glucose” where the blood sugar amount is produced by the liver and carried by red blood cells, not the blood itself. Fasting plasma glucose (FPG) has nothing to do with either diet or exercise during sleep hours and is mainly relying on the health condition of both liver and pancreatic beta cells, which produces glucose and releases insulin, to control the glucose level in blood. Therefore, it is nearly impossible to measure the material geometry or material properties to determine the viscosity of “glucose” like in engineering research work. As a result, the best the author could do is to apply the “concept of viscoelasticity and/or viscoplasticity” to construct an analogy model of time-dependent glucose behaviors.

Viscoelastic and Viscoplastic Glucose Theory (VGT #30): Applying VGT with Two Different CGM Sensor Measured 3-Hour Postprandial Plasma Glucose (PPG) Values from 240 Liquid Egg Meals and 191 Solid Egg Meals as the Strain, Along with the PPG Change Rate Multiplied by a Viscosity Factor of Average Carbs/Sugar Amounts for Each Egg Meal Type as the Stress, and then Applying

The author has studied strength of materials and theory of elasticity through his undergraduate courses at the University of Iowa. He also conducted research work on UI campus to earn a master’s degree in Biomechanics under Professor James Andrews. At that time, he used a combined spring and dashpot model to simulate the behaviors of human joints, bones, muscles, and tendons in order to investigate the human-weapon interactions during the Vietnam war era. Later, he went to MIT to pursue his PhD study under Professor Norman Jones, who taught him theory of plasticity and dynamic plastic behaviors of various structure elements. He also took additional graduate courses in the field of fluid dynamics and thermodynamics along the way of his schooling years. Since then, many advancements have been made in the biomechanics branch, especially with human body tissues that possess certain viscoelastic characteristics, such as bones, muscles, cartilages, tendons (connect bone to muscle), ligaments (connect bone to bone), fascia, and skin. For example, the author suffered plantar fasciitis for many years. He understood that the night splint dorsiflexes forefoot, at the back of the foot, increases plantar fascia tension to offer stress-relief for the pain. This model where muscles and tendons connect the lower leg and foot is a form of viscoelastic study for medical problem solving. When dealing with human internal organs, it is not easy to conduct live experiments to obtain accurate measurements for the biomedical material properties. Blood itself is a viscous material (time-dependent) and its viscosity factor may fall between water, honey, syrup, or gel. The author’s research focuses on “glucose” where the blood sugar amount is produced by the liver and carried by red blood cells, not the blood itself. The postprandial plasma glucose (PPG) is strongly influenced by both energy input via carbs/sugar intake amount (~60%) and energy output via post-meal exercise level (~40%). Fundamentally, the PPG level is also dependent on the individual's health conditions in regard to liver cells and pancreatic beta cells, which produce glucose and release insulin to control the glucose level in blood. Therefore, it is nearly impossible to measure the material geometry or material properties to determine the viscosity of “glucose” like in engineering research work. As a result, the best the author could do is to apply the “concept” of viscoelasticity and/or viscoplasticity” to construct an analogy model of time-dependent glucose behaviors.

Thermo-fluid dynamics modelling of steam electrolysis in fully-assembled tubular high-temperature proton-conducting cells

Electrolysis based on renewable energies offers a promising carbon-free solution for hydrogen generation and storage. The recent developments of proton ceramic electrolysis cells operating at intermediate temperatures bear promise of superior energy efficiency compared to oxide ion conducting electrolytes. Here, a proton ceramic Single Engineering Unit (SEU) design is optimized for steam electrolysis using a computational fluid dynamics (CFD) model implemented in a COMSOL Multiphysics software. The SEU is an all-in-one tubular cell arrangement that constitutes the smallest electrolysis unit and enables efficient, adaptable pressurized hydrogen generation. The parametrical modelling study is conducted for two adiabatic operation scenarios with distinct steam conversion rates and tested for multiple key parameters, namely internal and external chamber pressures and inlet stream temperature. The modelling results show that low steam conversions enable operation at higher current densities and that the thermoneutral voltage for a fixed steam conversion is highly sensitive to the process conditions and operation modes. The increment of the pressure of the generated hydrogen implies a reduced production rate at thermoneutral voltage, although it can be compensated with an enhanced steam pressure or a reduced inlet temperature. Additionally, the introduction of a porous medium as the SEU current collector in the steam chamber enhances heat transport within this chamber. The area specific resistance of the system determines the current density, enforcing an adaption of the area of the electrolyser to satisfy the target hydrogen production and energy efficiency. The resulting proposed SEU design and adapted operational parameters allow effective delivery of pressurized dry hydrogen for a wide range of conditions and applications.

The Thermal Effect of Submarine Mud Volcano Fluid and Its Influence on the Occurrence of Gas Hydrates

Mud volcanoes and other fluid seepage pathways usually transport sufficient gas for the formation of gas reservoirs and are beneficial to the accumulation of gas hydrate. On the other hand, the fluid thermal effects of mud volcanoes can constrain the occurrence of gas hydrates. Current field measurements indicate that fluid thermal anomalies impact the distribution of gas hydrates associated with mud volcanoes. However, due to the lack of quantitative analysis of the mud volcano fluid flow and thermal evolution, it is difficult to effectively reveal the occurrence of gas hydrates in mud volcano development areas and estimate their resource potential. This study took the Håkon Mosby Mud Volcano (HMMV) in the southwestern Barents Sea as the research object and comprehensively used seismic, well logging, drilling and heat flow survey data, combining the principles and methods of fluid dynamics and thermodynamics to study the fluid flow and heat transfer of a mud volcanic pathway. The space framework of the mud volcanic fluid temperature field thermal structure was established, the influence of the HMMV fluid thermal effect on gas hydrate occurrence was analyzed and the distribution and resource potential of gas hydrates in mud volcano development areas were revealed from the perspective of thermodynamics. This study provides a thermodynamic theoretical basis for gas hydrate accumulation research, exploration and exploitation under a fluid seepage tectonic environment.

Thermodynamic perfect fluid spheres admitting an orthogonal flat synchronization

We analyze the interpretation of the spherically symmetric perfect fluid solutions that admit a flat synchronization orthogonal to the fluid flow as a thermodynamic perfect fluid in local thermal equilibrium. The ideal gas sonic condition is examined for this family of metrics, and the macroscopic conditions for physical reality are accurately tested for some specific solutions.

Viscoelastic Glucose Theory (VGT #1): Applying the Concept of Viscoelasticity Theory to Conduct a “Glucose Analogy” Study and Illustrate Certain Viscoelastic Characteristics of Time-Dependent Glucose Using Continuous Glucose Monitoring (CGM) Sensor Device Collected Postprandial Plasma Glucose (PPG) Data of 4,056 Elastic Glucoses (<180 mg/dL) within 3.7 Years from 5/8/2018 to 1/10/2022 Based on GH-Method: Math-Physical Medicine (No. 578)

The author has studied the strength of materials and theory of elasticity from undergraduate courses at the University of Iowa. He also conducted research work to earn a master’s degree in Biomechanics under Professor James Andrews. He remembers that he used both spring and dashpot models to simulate the behaviors of human bone, muscle, and tendon to investigate the human-weapon interactions. Later on, he went to MIT to pursue his Ph.D. study under Professor Norman Jones who taught him the theory of plasticity and dynamic plastic behaviors of various structural elements. Furthermore, he took some graduate courses at MIT in the field of fluid dynamics and thermodynamics. Since then, biomechanics has made advancements in a few application areas, especially tissues of the human body which possess viscoelastic characteristics, such as bone, muscle, cartilage, tendon (connect bone to muscle), ligament (connect bone to bone), fascia and skin. For example, the night splint dorsiflexes forefoot on rear foot increasing plantar fascia tension to offer stress-relaxation of plantar fascia pain. This model of muscles and tendons connecting lower-leg and foot is a kind of viscoelastic problem. However, when we deal with human internal organs, it is not easy to conduct live experiments to obtain some accurate measurements of material properties. Although blood itself is a viscous material which viscosity factor may sit between water and honey, syrup, or gel. But, the author’s research subject is “glucose”, the sugar amount inside of blood or carried by blood cells, not the blood itself. It is near impossible to measure the material geometry or engineering properties of glucose, for example, the viscosity of “glucose”. Therefore, the best he could do is to apply the concept of viscoelasticity and viscoplasticity to construct an analogy motor to study the glucose behaviors which are time-dependent. The author’s background covers mathematics, physics, and various engineering disciplines, not including biology and chemistry. As a result, he can only investigate the observed biomedical phenomena using his ready-learned math-physical tools.

Viscoelastic and Viscoplastic Glucose Theory (VGT #2): Applying the Concept of Viscoelasticity and Viscoplasticity to Conduct a “Time-Dependent Glucose Analogy” Study of An Elastic Glucose Case Covering 4,056 meals <180 mg/ dL Versus Plastic Glucose Case of 23 Meals >180 mg/dL Using Collected Postprandial Plasma Glucose Data from 4,079 Meals over 3.7-Year Period from 5/8/2018 to 1/10/2022 Based on GH-Method:

The author has studied strength of materials and theory of elasticity through his undergraduate courses at the University of Iowa. He also conducted research work to earn a master’s degree in Biomechanics under Professor James Andrews. He remembers using the spring and dashpot models to simulate the behaviors of human joints, bones, muscles, and tendons to investigate the human-weapon interactions. Later, he went to MIT to pursue his PhD study under Professor Norman Jones, who taught him theory of plasticity and dynamic plastic behaviors of structure elements, and took additional graduate courses in the field of fluid dynamics and thermodynamics. Since then, many advancements have been made in biomechanics in a few application areas, especially tissues of the human body which possess viscoelastic characteristics, such as bone, muscle, cartilage, tendon (connect bone to muscle), ligament (connect bone to bone), fascia, and skin. For example, the night splint dorsiflexes forefoot at the back of the foot increases plantar fascia tension to offer stress-relaxation for plantar fascia pain. This model of muscles and tendons connecting the lower leg and foot is a type of viscoelastic problem. However, when dealing with the human internal organs, it is not easy to conduct live experiments to obtain accurate measurements of material properties. Although blood itself is a viscous material, the viscosity factor may fall between water, honey, syrup, or gel. However, the author’s research subject is “glucose”, the sugar amount in blood carried by cells, not the blood itself. It is nearly impossible to measure material geometry or certain engineering properties of glucose, for example, the viscosity of “glucose”. Therefore, the best he could do is to apply the

Comparative Assessment of Different Turbulence Models to Estimate Thermo-Fluid Characteristics of an Infrared Suppression (IRS) Device

AbstractThe accurate computation to predict the heat transfer and flow characteristics in an IRS system is challenging because of the complex designs of thermo-fluid dynamics, such as the entrainment of cold atmospheric air and mixing with the hot exhaust from the gas turbine housed in naval or cargo ships. This study considers the IRS device with four cylindrical funnels stacked one above the other. This study aims to find the suitable turbulence model(s) for numerical modeling of the IRS device. The Reynolds number based on the nozzle diameter is varied between 3527 and 7231 (laboratory-scale) and 4×105 to 5×105 (real-scale) as per the availability of the experimental data. Eight turbulence models, viz., standard k−ε, RNG k−ε (with standard wall function and enhanced wall functions), realizable k−ε, low Reynold number (LRN) Launder-Sharma k−ε, low Reynold number (LRN) Yang-Shi k−ε, standard k−ω, k−ω SST, v2−f are used to model the complex entrainment and mixing process inside the IRS device. The LRN-LS model estimates the thermos-fluid dynamics quite accurately for the lower Reynolds number range (laboratory-scale IRS), and SST k−ω model predicts accurately for higher Reynolds number values (real-scale IRS). We believe that the present study would help further the numerical modeling of IRS devices.

Waste heat recovery using Tesla turbines in Rankine cycle power plants: Thermofluid dynamic characterization, performance assessment and exergy analysis

• Compressible-turbulent flow physics of wet steam in Tesla turbines is studied to assess power recovery. • Scaling laws are modified by introducing a novel thermal parameter ( Ts ). • Optimal rotor dimensions in terms of rotor and second law efficiencies are determined for different inlet angles. • Maximum power decreases and efficiency increases with decreasing steam quality. The Tesla turbine with insulated rotors has been investigated numerically and analytically for the application in Rankine cycle power plants for waste heat recovery. Simulations are performed for the multiphase, compressible, turbulent flow of wet steam to study the thermofluid dynamics and performance characteristics for a wide range of dimensional and dimensionless parameters. The expansion of steam inside the rotor is verified by density and Mach number contours. The increase in radius and inlet angle seems to increase the power obtained, with the maximum total recoverable power reaching as high as 2 M W using 750 m m rotors for inlet angle 3 ° , keeping in view the efficiency. The efficiency curves are compared with that of the laminar, incompressible flow of air, which seems to follow a similar qualitative nature but with a significant decrease in the effect of inlet angle. Fuel cost estimation of a 2000 M W power plant employing the Tesla turbines that use 20 % bled steam is performed and encouraging preliminary reduction in cost is observed. The previously derived scaling laws have been modified and extended to include thermal similarity characteristics using a new dimensionless parameter ( T s ) . Exergy analysis is performed on the rotors, which show that the second law efficiency seems to follow a decreasing trend with increasing inlet angle similar to the rotor efficiency. Sharp drops in rotor and second law efficiencies are observed when the dynamic similarity number Ds drops or rotor radius increases beyond certain values. The exergy destruction seems to increase exponentially with increasing radius. Impact on the performance by the variation of the dryness fraction of wet-steam has been reported for steam qualities 0.8 - 0.95 . Although the obtainable power decreases with the dryness fraction, the rotor and second law efficiency seem to increase, cementing the previous claims of the ability of Tesla turbines to perform efficiently at poor steam qualities.

Immersed boundary method and virtual physical model for onset turbulence flow around complex geometry / Método de fronteira imersa e modelo físico virtual para fluxo de turbulência de início em torno de geometria complexa

An immersed boundary method is development for the fluid-body interaction, being consider the heat-transfer for the onset turbulence in two-dimensional (2D) thermofluid dynamics around isothermal complex geometries immersed in incompressible Newtonian flows. The fluid motion and temperature are defined on a fixed Eulerian grid, while the immersed body is defined on a Lagrangian grid. A virtual physical model is used for the diffusion of interfacial forces within the flow, guarantees the imposition of the no-slip boundary condition. This model dynamically evaluates not only the force that the fluid exerts on the solid surface, but the heat exchange between them. Therefore, this work presents the Navier-Stokes equations, together with the energy equation, under physically appropriate boundary conditions. To calculate the turbulence viscosity, was used the Smagorinsky model, implemented in the context of the Large Eddy Simulation (LES) model. This work confirms that, downstream of the immersed body, the recirculation: 1) increases with the increase in the number of Reynolds, keeping the numbers of Richardson constant, and 2) decrease with the increase in the number of Richardson, preserving the number of Reynolds constant. It also confirms the generation of the thermal plumes moving upwards. The results are compared with previous numerical results, considering different Reynolds numbers.

Preface

The 2021 UIT (Italian Union of Thermo-Fluid Dynamics) International Conference, hereafter referred as 38th UIT 2021, was organized by the Department of Civil and Mechanical Engineering of the University of Cassino (Italy), in collaboration with the UIT, on June 21st- 23rd 2021.The 38th UIT Heat Transfer Conference 2021 was organized by the Organizing Committee of the 38th UIT Heat Transfer Conference, initially scheduled for June 21st-23rd 2021 at the Castello di Gaeta, Italy. Considering the criticalities induced by the spread of COVID-19, difficulties in travelling, social distancing, and strict rules to follow, the Organizing Committee made the difficult decision to organize the 38th UIT Heat Transfer Conference 2021 completely online on June 21st-22nd 2021, using the platform Google Meet, to give the opportunity to the authors to introduce their valuable papers in 11 online parallel technical sessions. A total of 58 abstracts were submitted to the 38th UIT Heat Transfer Conference 2021, 45 of which presented by the Authors in oral sessions, while the remaining13 abstracts were presented in poster sessions.The 38th UIT Heat Transfer Conference 2021 program scheduled a plenary lecture given by Prof. Giovanni Betta from the University of Cassino and Southern Lazio, while each author confined his talk in 15 minutes, including questions and answers. The majority of participants were from Italy, with a total number of about 70 researchers connected to the 38th UIT 2021 online event.List of Committees, Co-chairs, International Advisory Committee, Local Organising Committee and Contact details for the declaration this titles are available in this pdf.

Multiphysics Analyses of the Bottom Components of the 3D Printed Transformational Challenge Reactor

This work presents multiphysics analyses on the bottom components of the Transformational Challenge Reactor (TCR) facility. These components include the bottom axial reflector and the steel exit cone. The bottom axial reflector is made of pure silicon carbide elements hosting helium cooling channels. These elements are three-dimensional (3D) printed, and therefore can host any arbitrary shape of the helium cooling channels. The design of the bottom reflector considers the neutronics and thermofluid dynamics performances as well as the manufacturing process optimization. More precisely, the best design of the bottom reflector reduces neutron leakage by avoiding straight cylindrical helium channels that facilitate neutron leakage, minimizes the helium flow pressure drop, and reduces the number of 3D printed silicon carbide pieces. The exit cone steel structure collects the hot helium from the bottom fuel assemblies and channels the cold helium to the top of the fuel assemblies. The steel’s simultaneous contact with hot and cold helium flows sets a large thermal gradient. Different designs of the exit cone are proposed to reduce the steel equivalent stress from the helium thermal load. The multiphysics analyses have been performed using Ansys Fluent, Ansys Mechanical, STAR-CCM+, and Serpent computer programs.

Viscoelastic and Viscoplastic Glucose Theory (VGT #30): Applying VGT with two Different CGM Sensor Measured 3-Hour Postprandial Plasma Glucose (PPG) Values from 240 Liquid Egg Meals and 191 Solid Egg Meals as the Strain, Along with the PPG Change Rate Multiplied by a Viscosity Factor of Average Carbs/Sugar Amounts for Each Egg Meal Type as the Stress, and then Applying

The author has studied strength of materials and theory of elasticity through his undergraduate courses at the University of Iowa. He also conducted research work on UI campus to earn a master’s degree in Biomechanics under Professor James Andrews. At that time, he used a combined spring and dashpot model to simulate the behaviors of human joints, bones, muscles, and tendons in order to investigate the human-weapon interactions during the Vietnam war era. Later, he went to MIT to pursue his PhD study under Professor Norman Jones, who taught him theory of plasticity and dynamic plastic behaviors of various structure elements. He also took additional graduate courses in the field of fluid dynamics and thermodynamics along the way of his schooling years. Since then, many advancements have been made in the biomechanics branch, especially with human body tissues that possess certain viscoelastic characteristics, such as bones, muscles, cartilages, tendons (connect bone to muscle), ligaments (connect bone to bone), fascia, and skin. For example, the author suffered plantar fasciitis for many years. He understood that the night splint dorsiflexes forefoot, at the back of the foot, increases plantar fascia tension to offer stress-relief for the pain. This model where muscles and tendons connect the lower leg and foot is a form of viscoelastic study for medical problem solving. When dealing with human internal organs, it is not easy to conduct live experiments to obtain accurate measurements for the biomedical material properties. Blood itself is a viscous material (time-dependent) and its viscosity factor may fall between water, honey, syrup, or gel. The author’s research focuses on “glucose” where the blood sugar amount is produced by the liver and carried by red blood cells, not the blood itself. The postprandial plasma glucose (PPG) is strongly influenced by both energy input via carbs/sugar intake amount (~60%) and energy output via post-meal exercise level (~40%). Fundamentally, the PPG level is also dependent on the individual’s health conditions in regard to liver cells and pancreatic beta cells, which produce glucose and release insulin to control the glucose level in blood. Therefore, it is nearly impossible to measure the material geometry or material properties to determine the viscosity of “glucose” like in engineering research work. As a result, the best the author could do is to apply the “concept” of viscoelasticity and/or viscoplasticity” to construct an analogy model of time-dependent glucose behaviors.

Viscoelastic and Viscoplastic Glucose Theory (VGT #29): Applying viscoelastic Glucose Theory with CGM Sensor Measured Fasting Plasma Glucose (FPG) Values as the Strain along with the FPG Change Rate Multiplied by a Viscosity Factor as the Stress, and Finally Utilizing the Viscoelastic Perturbation Model to Calculate the Predicted FPG Values to Compare Against the Measured FPG Values Based on GH-Method:

The author has studied strength of materials and theory of elasticity through his undergraduate courses at the University of Iowa. He also conducted research work to earn a master’s degree in Biomechanics under Professor James Andrews. At that time, he used the spring and dashpot models to simulate the behaviors of human joints, bones, muscles, and tendons in order to investigate the human-weapon interactions during the Vietnam war era. Later, he went to MIT to pursue his PhD study under Professor Norman Jones, who taught him theory of plasticity and dynamic plastic behaviors of various structure elements. He also took additional graduate courses in the field of fluid dynamics and thermodynamics. Since then, many advancements have been made in the biomechanics branch, especially with human body tissues that possess certain viscoelastic characteristics, such as bones, muscles, cartilages, tendons (connect bone to muscle), ligaments (connect bone to bone), fascia, and skin. For example, the author suffered plantar fasciitis for many years. He understood that the night splint dorsiflexes forefoot, at the back of the foot, increases plantar fascia tension to offer stress-relaxation for the pain. This model where muscles and tendons connect the lower leg and foot is a form of viscoelastic study for medical problem solving. When dealing with human internal organs, it is not easy to conduct live experiments to obtain accurate measurements for the biomedical material properties. Blood itself is a viscous material (time-dependent) and its viscosity factor may fall between water, honey, syrup, or gel. The author’s research focuses on “glucose” where the blood sugar amount is produced by the liver and carried by red blood cells, not the blood itself. Fasting plasma glucose (FPG) has nothing to do with either diet or exercise during sleep hours and is mainly relying on the health condition of both liver and pancreatic beta cells, which produces glucose and releases insulin, to control the glucose level in blood. Therefore, it is nearly impossible to measure the material geometry or material properties to determine the viscosity of “glucose” like in engineering research work. As a result, the best the author could do is to apply the “concept of viscoelasticity and/or viscoplasticity” to construct an analogy model of time-dependent glucose behaviors.

CFD analysis of environmental impacts on a thermochromic smart window

Thermochromic (TC) glazing is an advanced smart window technology that can help to achieve nearly zero-energy buildings. The glazing temperature that affects TC thermo-optical properties directly impacts its energy-saving performance. However, the impacts of solar radiation and natural convection occurring on this temperature-sensitive material are not yet fully understood. Compared to previous focuses on material properties and energy evaluation, this study aimed to provide a different view from thermo-fluid dynamics on the heat transfer characteristics of a TC window, with impacts of environmental factors addressed. A validated Computational Fluid Dynamics (CFD) model identifies the environmental impacts on the TC glazing temperatures under the coupled radiative and convective heat transfer. Furthermore, a theoretical model was developed with an empirical factor obtained from CFD results. It enables a simple calculation to obtain the TC glazing’s temperature by using solar factors, outdoor temperatures and optical properties. The model suggests that the temperature difference between the TC glazing and the ambient is a function of absorbed solar irradiation (∝q̇total0.75). The predictive model is then tested using typical climate conditions in three cities in China with different solar angles, which demonstrates good agreement with an average absolute error of 5% compared to simulated glazing temperature. This estimation method can further assist in material design, product selection and Building Energy Simulations to achieve a TC window design that is ‘smart’ on seasonal change requirements for different regions.