bluuebunny/crossref_metadata_2025_split huggingface dataset:
Neutron Imaging of a Two-Phase Refrigerant Flow
Authors: Geoghegan Patrick , Sharma Vishaldeep 
Published: March 2016

Void fraction remains a crucial parameter in understanding and characterizing two-phase flow. It appears as a key variable in both heat transfer and pressure drop correlations of two-phase flows, from the macro to micro-channel scale. Void fraction estimation dictates the sizing of both evaporating and condensing phase change heat exchangers, for example. In order to measure void fraction some invasive approach is necessary. Typically, visualization is achieved either downstream of the test section or on top by machining to expose the channel. Both approaches can lead to inaccuracies. The former assumes the flow will not be affected moving from the heat exchanger surface to the transparent section. The latter distorts the heat flow path.
Neutron Imaging can provide a non-invasive measurement because metals such as Aluminum are essentially transparent to neutrons. Hence, if a refrigerant is selected that provides suitable neutron attenuation; steady-state void fraction measurements in two-phase flow are attainable in-situ without disturbing the fluid flow or heat flow path.
Neutron Imaging has been used in the past to qualitatively describe the flow in heat exchangers in terms of maldistributions without providing void fraction data. This work is distinguished from previous efforts because the heat exchanger has been designed and the refrigerant selected to avail of neutron imaging.
This work describes the experimental flow loop that enables a boiling two-phase flow; the heat exchanger test section and downstream transparent section are described. The flow loop controls the degree of subcooling and the refrigerant flowrate. Heating cartridges embedded in the test section are employed to control the heat input. Neutron-imaged steady-state void fraction measurements are captured and compared to representative high-speed videography captured at the visualization section. This allows a qualitative comparison between neutron imaged and traditional techniques. The measurements are also compared to correlations in the literature.
Preliminary void fraction images from a macro-channel flow are presented, consisting of 1 channel, 4mm wide, 4mm high and 83.32mm long. Flow regime identification is examined.
The experiments were conducted at the High Flux Isotope Reactor (HFIR) Cold Guide 1D neutron imaging facility at Oak Ridge National Laboratory, Oak Ridge, TN, USA.
Transient Interface Shape and Deposition Profile Left by Desiccation of Colloidal Droplets on Multiple Surfaces
Authors: Dunning Peter D. , Greyson Marcette , Schertzer Michael J. 
Published: March 2016

Abstract
Control of deposition patterns left by desiccated colloidal droplets is valuable in applications ranging from medical diagnostics to inkjet printing. This investigation presents an experimental method to monitor the transient interface shape of a colloidal droplet during desiccation and to quantify the deposition pattern left by the colloidal material optically. Transient image profiles and particle deposition patterns are examined for droplets containing fluorescent particles that were desiccated on glass and on the photoresist SU-8 3005. Contact line pinning was more prevalent on glass, where the contact diameter remained approximately constant throughout the process and the contact angle decreased with time. On SU-8, the contact diameter was initially constant, but decreased after the contact angle was reduced. The initial contact diameter on glass was similar to the diameter of the deposition pattern. The diameter of the deposition pattern on SU-8 was approximately half of the initial contact diameter. The deposition on SU-8 was also observed to be more uniform than that left on glass. These results suggest that selection of an appropriate substrate is an important consideration for colloidal deposition. The method presented will be used to in future investigations to characterize the effectiveness of coffee stain suppression through the application of external electric fields.
Separation of Radiative and Convective Wall Heat Fluxes Using Thermal Infrared Measurements Applied to Flame Impingement
Authors: Gomez-Ramirez David , Ekkad Srinath V. , Lattimer Brian Y. , Moon Hee-Koo , Kim Yong , Srinivasan Ram 
Published: March 2016

Flame impingement is critical for the processing and energy industries. The high heat transfer rates obtained with impinging flames are relevant in metal flame cutting, welding, and brazing; in fire research to understand the effects of flames on the structures of buildings; and in the design of high temperature combustion systems. Most of the studies on flame impingement are limited to surfaces perpendicular to the flame, and measurements are often performed using heat flux sensors (such as Schmidt-Boelter heat flux transducers) at discrete locations along the target surface. The use of in-situ probes provides high accuracy but heavily limits the spatial resolution of the measurement. Moreover, flame radiation effects are often neglected, due to the small contribution in non-luminous flames, and the entire heat flux to the target is assumed to be due to convection. Depending on the character of the flame and the impingement surface, local radiative heat transfer can be significant, and the contribution of radiation effects has not been fully quantified.
This study presents a novel non-intrusive method with high spatial resolution to simultaneously determine the convective and radiative heat fluxes at a wall interacting with a flame or other high temperature environment. Two initial proof of concept experiments were conducted to evaluate the viability of the technique: one consisting of a flame impinging normal to a target and another with a flame parallel to the target surface. Application of the methodology to the former case yielded a stagnation convective heat flux in the order of 106kWm−2 that decreased radially away from the stagnation point. The radiation field for the direct impingement case accounted on average for 4.4% of the overall mean heat flux. The latter experiment exemplified a case with low convective heat fluxes, which was correctly predicted by the measurement. The radiative heat fluxes were consistent between the parallel and perpendicular cases.
Biomechanical and Biochemical Study of Muscle-Tendon-Bone in Porcine Digital Flexor Tendon
Authors: Danley Bryan B. , Huang Shadow 
Published: March 2016

The musculoskeletal system provides the body with both movement and support. In particular, contractile forces developed in the muscles are transmitted through the muscle-tendon junction (MTJ) into the tendon and then through the tendon-bone insertion into the bone. Each junction occurs between two dissimilar materials (muscle-to-tendon and tendon-to-bone) and neither is fully understood. The current study analyzes the relationship between the tissue microstructure and macro-scale biomechanical properties of the muscle-tendon-bone unit to better understand the anisotropic mechanical behavior of the tissue. Collagen content was assayed at various locations along the porcine digital flexor tendon. Collagen concentration as a percent of the wet weight in the bone end was found to be 20.4±5.2% (n=6), the mid tendon to be 20.6±5.3% (n=6), and the muscle end to be 25.2±3.6% (n=4). No statistical differences were found between these collagen concentrations.
Additionally, to the best of the authors’ knowledge, this is the first study to report cross-sectional stress-strain data for the muscle-tendon-bone unit. Results indicate that the tendon cross-sectional stiffness increases from the proximal end to the distal end. However, no direction dependent anisotropies were found between the mediolateral and dorsopalmar directions. Effects of microstructural components, such as glycosaminoglycans and collagen, and phenomenon such as fibril sliding and cross-linking, are discussed in relation to the reported cross-section stress-strain response. This work provides a synergistic approach for quantifying biomechanical and biochemical properties of biological tissue, and potentially facilitates the development of tissue engineered MTJ and tendon-bone insertion.
Experimental Measurement of Vacuum Assisted Drying of Spent Nuclear Fuel
Authors: Rivera Matthew , Manteufel Randall 
Published: March 2016

A prevalent issue within extended long term dry storage units for spent nuclear fuel has always been fuel and cask contamination. This contamination can be the result of the helium within the cask leaking into the atmosphere or inadequate vacuum drying techniques. Once the cask integrity has been compromised, the helium starts to leak, and the resulting space once occupied by helium in the casks is replaced with ambient air. One of the other prominent gases found within ambient air besides oxygen is water vapor which can be a result of both helium leaking and poor vacuum drying techniques. Contact between water and the fuel rods/assemblies for a prolonged amount of time can result in corrosion of the fuel cladding, and the canister if exposed. The potential of corrosion of the fuel cladding increases risk of radioactive fission fragments contaminating the environment, increases the radioactive period of spent nuclear fuel, and decreases the potential for fuel rod repurposing within the future if U.S. law permits.
With literary findings showing liquid water within the inner cask in a long term storage unit of fifteen years or longer, proper drying techniques have not been fully developed. There are a number of projected theories about how water is entering the cask without an external crack or imperfection within the inner cask walls. This case study aims to solve this issue by inspecting the vacuum drying process of the fuel rods/assemblies from the temporary on-site storage pools to their respective long term dry storage casks.
The purpose of this case study is to conduct a laboratory experiment of a scale replica of one dry storage cask and the vacuum drying process before long term storage. The experiment will be focused around the process of applying several cycles of vacuum and backfilling the cask with Helium. The purpose of several cycles of backfilling gas is to simultaneously introduce more of a pressure gradient for water evaporates to depart the pressure vessel and to avoid thermodynamic temperatures that would otherwise freeze the top layer of water. To do this, the vacuuming process must be properly understood, as pulling a vacuum drops pressures instantaneously. There are possibilities of freezing water vapor into its solidified form due to its thermodynamic triple point during this vacuum process. Once water is trapped under a layer of ice within the vessel, water will remain throughout storage time due to restrictions to its own geometries. The importance of developing a scale model and improving the drying process that precedes long term storage of spent nuclear fuel is a necessary solution to existing contamination results for practical future applications within the United States and other countries moving towards long term storage of spent nuclear fuel.
Design of a Screw Heat Exchanger as the Liquid-Suction Heat Exchanger in a Vapor Compression Refrigeration System
Authors: Antonio Francis J. , Berana Menandro S. , Danao Louis Angelo M. 
Published: March 2016

The aim of this study is to optimize the design of a screw heat exchanger (SHX) in terms of varying coil aspect ratio (CAR) as a liquid-suction heat exchanger (LSHE) in a vapor compression refrigeration system through Computational Fluid Dynamics (CFD) simulation. The novelty of this study is that it focuses on the fluid-to-fluid heat transfer of SHX to measure its heat transfer effectiveness as compared to many research studies that focus only on helical duct heat exchanger under constant wall temperature and constant heat flux. Optimization of the SHX was done through conjugate heat transfer in a CFD model. High confidence on the computational package was determined as the results of the package on heat transfer between water flows through a shell-and-coil heat exchanger match well with available experimental data of the same setup in related literature.
The performance of SHX with square coil section (SHXSCS) was compared to that of the SHX with circular coil section (SHXCCS). The optimum SHXSCS was then compared to a commercially available LSHE in the form of tube-in-tube heat exchanger (TTHE) which is the most commonly used LSHE in vapor compression refrigeration systems.
The SHXSCS has nominal degrees of superheat of 22.17 °C and nominal degrees of subcool of 17.63 °C. The ratio of the heat of superheating to that of subcooling is seen to increase with increasing CAR and NTU. The RE of SHXSCS is larger by an average of 3.87%, 18.25% and 26.46% compared to those of the SHXCCS, TTHE and the standard vapor compression cycle (VCC), respectively. The COP of the SHXSCS is 2.55%, 10.74% and 5.94% higher than those of the SHXCCS, TTHE and the standard VCC, respectively. The SHXSCS is more capable than SHXCCS in splitting the heat due to the less complicated square cross sections of flows and even less interface materials for heat transfer. Moreover, the SHXSCS is more effective in splitting the heat from subcooling into moderated superheating and largely to the surounding compared to the TTHE mainly due to longer length of interaction of the flows.
Preliminary Analysis of an Innovative Rotary Displacer Stirling Engine
Authors: Bagheri AmirHossein , Bostanci Huseyin , Foster Philip R. 
Published: March 2016

The Stirling cycle has recently been receiving renewed interest due to some of its key inherent advantages. In particular, the ability to operate with any form of heat source (including external combustion, flue gases, alternative (biomass, solar, geothermal) energy) provides Stirling engines a great flexibility and potential benefits for many applications. However, several aspects of traditional Stirling engine configurations (i.e., the Alpha, Beta, and Gamma), specifically complexity of design, high cost, and relatively low power to size and power to volume ratios, limited their widespread applications to date. This study focuses on an innovative Stirling engine configuration that features a rotary displacer (as opposed to common reciprocating displacers), and aims to utilize a preliminary analytical analysis to gain insights on its operation parameters. Although the analysis involves idealizations, it still provides useful design guidelines as a first step towards optimization.
This study adopts some of the assumptions from the well-known Schmidt analysis, and follows a similar approach for the innovative rotary displacer configuration. As part of this preliminary analysis the optimum phase (lead) angle is determined to be 90°. In addition, the work ratio normalized for the optimum phase angle is presented. Other studied parameters include the internal volume of rotary displacer over the volume of power cylinder, and the volume of “dead spaces” over the volume of power cylinder at various ratios. Although the dead space have negative effects on overall performance and efficiency, they are dictated by the practical design constraints. Lastly, this study considers work output of the engine over a range of heat sink to heat source temperature ratios, and varies the heat sink or heat source temperatures independently. The analysis addresses both low and high temperature differential situations for the purpose of waste heat recovery and power generation, respectively.
Reconfigurable Compliant Cellular Material With Programmable Compliant Cellular Structure
Authors: Kang Ye , Kim Kwangwon , Ju Jaehyung 
Published: March 2016

Cellular materials have two important properties: structures and mechanisms. This property enables one to design structures with proper stiffness and flexibility. Recent advance in 3D printing technologies enable engineers to manufacture complex cellular structures. In addition, use of smart materials, e.g., shape memory polymers (SMPs), for 3D printing enables us to construct mesostructures actively responsive to environmental stimuli with a programmable function, which may be termed ‘4D Printing’ referring to additional dimension on time-dependent shape change after 3D printing. The objective of this study is to design and synthesize active reconfigurable cellular materials, which enables the advance of technology on intelligent reconfigurable cellular structures with 4D printing. A two-layer hinge of a CPS functions through a programmed thermal expansion mismatch between two layers and shape memory effect of an SMP. Starting with thermo-mechanical constitutive modeling of a compliant porous hinge consisting of laminated elastomer composites, macroscopic behaviors of a reconfigurable compliant porous structure (CPS) will be constructed using the strain energy method. A finite element (FE) based simulation equipped with a user subroutine will be implemented with ABAQUS/Standard to simulate time-dependent thermo mechanical behaviors of a CPS.
The designed CPS with polymers shows an extremely high negative Poisson’s ratio (∼ −120) and negative thermal expansion coefficient (−2,530 × 10−6/C). When programmed with an appropriate thermo-mechanical procedure, the hinge of the CPS bends either in positive and negative sign, which enables to tailor the CPS into desired intermediate and final configurations, ending up with achieving a reconfigurable CPS. This paper demonstrates that actively reconfigurable compliant cellular materials (CCMs) with CPSes can be used for next-generation materials design in terms of tailoring mechanical properties such as modulus, strength, yield strain, Poisson’s ratios and thermal expansion coefficient together with programmable characteristics.
Development of Haptic-Enabled Virtual Reality Applications for Engineering, Medicine and Art
Authors: Medellín-Castillo Hugo I. , González-Badillo Germánico , Govea Eder , Espinosa-Castañeda Raquel , Gallegos Enrique 
Published: March 2016

The technological growth in the last years have conducted to the development of virtual reality (VR) systems able to immerse the user into a three-dimensional (3D) virtual environment where the user can interact in real time with virtual objects. This interaction is mainly based on visualizing the virtual environment and objects. However, with the recent beginning of haptic systems, the interaction with the virtual world has been extended to also feel, touch and manipulate virtual objects. Virtual reality has been successfully used in the development of applications in different scientific areas ranging from basic sciences, social science, education and entertainment. On the other hand, the use of haptics has increased in the last decade in domains from sciences and engineering to art and entertainment. Despite many developments, there is still relatively little knowledge about the confluence of software, enabling hardware, visual and haptic representations, to enable the conditions that best provide for an immersive sensory environment to convey information about a particular subject domain.
In this paper, the state of the art of the research work regarding virtual reality and haptic technologies carried out by the authors in the last years is presented. The aim is to evidence the potential use of these technologies to develop usable systems for analysis and simulation in different areas of knowledge. The development of three different systems in the areas of engineering, medicine and art is presented. In the area of engineering, a system for the planning, evaluation and training of assembly and manufacturing tasks has been developed. The system, named as HAMS (Haptic Assembly and Manufacturing System), is able to simulate assembly tasks of complex components with force feedback provided by the haptic device. On the other hand, in the area of medicine, a surgical simulator for planning and training orthognathic surgeries has been developed. The system, named as VOSS (Virtual Osteotomy Simulator System), allows the realization of virtual osteotomies with force feedback. Finally, in the area of art, an interactive cinema system for blind people has been developed. The system is able to play a 3D virtual movie for the blind user to listen to and touch by means of the haptic device. The development of these applications and the results obtained from these developments are presented and discussed in this paper.
Confinement Effects on Phase Behavior of Hydrocarbon in Nanochannels
Authors: Alfi M. , Nasrabadi H. , Banerjee D. 
Published: March 2016

Several researchers have recently studied the phase behavior of petroleum fluids in shale systems. There is a general agreement that the confined PVT properties in shale are substantially different from the corresponding bulk properties. These differences have significant impact on the prediction of well performance and ultimate recovery in shale reservoirs. Experimental measurements of fluid properties in shale rocks are currently not available. This has led to significant amount of uncertainty in phase behavior calculations for shale reservoirs.
In this study, experimental validation of numerical predictions for phase behavior of various hydrocarbons confined in nanochannels was performed using a nanofluidics platform. The nanofluidics platform was designed, fabricated and tested at different temperatures. Design of the nanochannel is described in this paper.
In this study, a nanochannel device (similar to Duan and Majumdar 2010) was designed, fabricated, packaged and tested. The reservoirs in the nanofluidic chip were filled with various hydrocarbon liquids (e.g. n-decane). The temperature was varied at a constant pressure, during which epifluorescence imaging was performed to measure the bubble nucleation temperature, i.e., the temperature corresponding to the formation of the first bubble of gas (i.e., to determine bubble-point pressure and temperature relationship).