bluuebunny/crossref_metadata_2025 huggingface dataset:
Software Tool Development for Grain Size Measurement Using ASTM Standards
Authors: Sirawattanachai Thanongsak , Daopiset Siriporn , Narasingha Somsak , Hassamontr Jaramporn
Published: November 2021

This research focuses on the development of a software tool to assist the validation of heat treating process through grain size measurement. Specifically, the software developed is to semi-automatically compute the average grain size from a black-and-white bitmap image taken from an image acquisition system. The technique used here is the intersection count and grain count methods. For the intersection count method, test grids can be of straight lines or circles. The magnification scale must be attached or input by users for calibration purposes. The image processing techniques are used to filter out irrelevant information and improve picture’s quality. The software will follow the standard guideline provided by ASTM E1382-91 to compute the average grain size. The software is developed as a stand-alone program running on a personal computer. Its performance is validated comparing its result with known input. The ASTM grain size numbers reported from the software are within 10% of those obtained using manual method. The software is efficient in terms of space requirement and computation time while requiring minimal user’s input. Moreover it is relatively inexpensive as compared to those software packages included with new image capturing systems.
A New Methodology for Ease-of-Disassembly in Product Design
Authors: Shetty Devdas , Rawolle Ken , Campana Claudio
Published: November 2021

As manufacturers are becoming responsible for their products when they reach the end of their operational lives, the dismantling of products has emerged as one of the serious part of this exercise. In situations involving integrated design principles, certain assembly procedures or joining techniques can make it very difficult to disassemble a product and to separate materials into non-contaminated groups. The strategy is to begin including design for disassembly guidelines in the current product design processes. Design for Disassembly (DFD) is a design philosophy that requires consideration to be given for a product or a part, even after it is in service. The inclusion of procedures for design for disassembly, recyclability and re-manufacture will save resources by prolonging the useful life of product. The paper initially examines the current state of the art in the area of Design for Disassembly and looks at the existing methodologies that are applicable to product design. A new methodology based on a combination of charts based on damage rating, tool rating, re-use rating and access-area rating is proposed. The methodology is compared with the existing methods and evaluated for various situations in aerospace industry.
Transient and Resonant Behavior of Electrically-Damped Microactuators
Authors: Chen Yijian , Shroff Yashesh , Oldham William G.
Published: November 2021

The transient and resonant behavior of electrostatic microactuators is investigated using the perturbation method and linear control theory. We examine an electrically-damped parallel-plate actuator and comb actuator in this paper. Two non-dimensional control parameters are identified and are shown to determine the system’s frequency response and the transient characteristics: damping, settling time, overshoot and stability. A transient optimization to minimize the settling time and overshoot of the time response to a step modulation is carried out using the ITAE (Integral of Time multiplied by Absolute Error) performance index. The optimal control parameters are obtained as well as the optimal resistance value and actuator geometry. The validity of our perturbation-based analysis is verified with numerical simulation. We also study the steady-state frequency response by assuming a sinusoidal input modulation. The response amplitude and the resonant frequency as a function of the control parameters are demonstrated.
High Aspect Ratio, High Resolution Ceramic MEMS
Authors: Routkevitch Dmitri , Govyadinov Alexander N. , Mardilovich Peter P.
Published: November 2021

Harsh application environments represent a dual challenge for MEMS. Not only are materials with high thermal, chemical, and mechanical stability required, but they should be also micromachinable at the 1 to 1000 micrometer scale. Current techniques, from ultra precision machining to ion milling and anisotropic etching, often have limited applicability for microprocessing of refractive materials, especially when high resolution and high aspect ratio are required at a reasonable cost. This presentation overviews the prior and current work on a novel ceramic MEMS technology based on the micromachining of anodic alumina.
Electrostatic Actuation of Microscale Liquid Metal Droplets: Analysis, Experiment, and FEM Simulation
Authors: Latorre Laurent , Kim Joonwon , Nouet Pascal , Kim Chang-Jin CJ
Published: November 2021

This paper investigates electrostatic actuation of microscopic liquid-metal droplets, typically mercury, for MEMS applications. Theory concerning droplets on a plane solid surface is briefly exposed, followed by the contact angle characterization, experiment for electrostatic actuation, and FEM analysis. Being a major parameter in the modeling of sliding droplets the contact angle has been characterized in the case of mercury on oxidized silicon wafer. The method used involves both traditional optical microscope and confocal laser imaging. On a set of 30 samples, the contact angle is found to be around 130° with an associated standard deviation of 8°, mostly due to measurement uncertainties. The sample preparation is detailed, based on selective condensation of mercury vapor on gold dots acting as preferred nucleation sites. This technique provides control on droplet dimensions and locations and is suitable for batch fabrication. Experimental study of electrostatic actuation coupled with FEM analysis is described. Results confirm the proportionality between minimum driving force and the droplet dimension. Finally, a modeling methodology is discussed using traditional FEM simulator calibrated with an equivalent Young’s Modulus concept.
Packaged Parylene-Diaphragm Piezoelectric Microspeaker
Authors: Han Cheol-Hyun , Kim Eun Sok
Published: November 2021

This paper describes our first demonstration of the parylene-diaphragm piezoelectric acoustic transducer as a fully functional microspeaker and also characterization of its vibration amplitude and sound pressure output. The piezoelectric microspeaker is built on a 1.5 μm thick parylene diaphragm (5,000*5000 μm2 square diaphragm micromachined in a silicon substrate) with electrodes and piezoelectric ZnO film. The parylene (a polymer material) has very low elastic modulus (about 50 to 100 times smaller than conventional diaphragm materials such as silicon nitride, stainless steel, etc), and is an outstanding material for a speaker application. The speaker is shown to produce a maximum sound-pressure level of 91 dB SPL into 2 cm3 acoustic coupler at a resonant frequency of 9.5 kHz. The vibration amplitude at that frequency is measured to be 1.8 μm with a laser doppler meter. Proper packaging of the microspeaker improves the sound output by preventing the cancellation of the sound output from the backside that has 180 degree out of phase.
Measurements and Modeling of Two-Phase Flow in Microchannels With Nearly-Constant Heat Flux Boundary Conditions
Authors: Zhang Lian , Koo Jae-Mo , Jiang Linan , Banerjee Shilajeet S. , Ashegi Mehdi , Goodson Kenneth E. , Santiago Juan G. , Kenny Thomas W.
Published: November 2021

Two-phase forced convective flow in microchannels can be used as an effective means of cooling microelectronics. However, the number of studies on boiling in microchannels with dimensions smaller than 100 microns is limited. Particularly, the impact of small dimensions on bubble formation and the critical heat flux have received little attention. This work develops single and multi-channel silicon test devices with integrated heaters and thermometers, in an effort toward precisely determining the flow condition, the temperature distribution, and the heat transfer coefficients within microchannels. Rectangular channels with hydraulic diameter below 100 microns and varying aspect ratios were fabricated. The test devices have channel walls with widths below 350 microns, which minimizes solid conduction along the test section and reduces variations in the heat flux boundary condition. A semiconductor resistor strip measures the wall temperature distribution along the channel during phase change. A thermal resistance model has been developed to estimate the heat loss from the system. Down to hydraulic diameters as small as 25 microns, nucleation boiling under 5 °C of wall superheating was observed in plasma etched silicon microchannels.
Anodic Oxidation and Reliability of MEMS Poly-Silicon Electrodes at High Voltages and in High Relative Humidity
Authors: Shea Herbert R. , White Carolyn D. , Gasparyan Arman , Comizzoli Robert B. , Arney Susanne
Published: November 2021

We present a study of the anodic oxidation of MEMS poly-Silicon electrodes and wires in ambients with high relative humidity and high voltages. MEMS poly-Si electrodes that are hermetically packaged in dry ambients show no signs of degradation on a time scale of years even when operated at hundreds of volts. To accelerate electrical failure modes, we expose unpackaged chips to ambients with high relative humidity. We then observe anodic oxidation of the most positively biased poly-Si structures on a time scale of minutes or hours. We describe this anodic oxidation as a function of relative humidity and voltage, and its dependence on surface leakage currents.
A Three-Axis Piezoresistive Micromachined Force Sensor for Studying Cockroach Biomechanics
Authors: Bartsch Michael S. , Partridge Aaron , Pruitt Beth L. , Full Robert J. , Kenny Thomas W.
Published: November 2021

A millimeter-scale silicon micromachined force sensor has been designed to measure in three axes the ground reaction forces produced by the cockroach Blaberus Discoidalis during typical running locomotion. Each sensor consists of a large-area (5mm × 5mm) rigid plate supported at its corners by thin flexures instrumented with two ion-implanted piezoresistors each. Comparison of piezoresistive measurements among these eight strain gauges allows the applied force to be resolved into three orthogonal components. Un-amplified sensitivity to normal forces of 1.2V/N has been demonstrated with estimated normal force resolution of 7.3μN on an 800Hz measurement bandwidth.
Packaging Technology for MEMS
Authors: Tan Qing
Published: November 2021

A review is given for MEMS devices fabricated using packaging materials. From reported literatures and patents, a variety of ceramic and plastic materials have been used for many microdevices. The green tape process for ceramic, flexible circuit and printed circuit board process platforms are all found to be suitable for 3-D, complex MEMS devices. In addition, micromolding and laser machining are reported for plastic materials. Devices fabricated from those materials include micromotors, sensors, biomedical chips, fuel cells, microchemical reaction chambers, micromirrors, microlens systems, etc. The introduction of packaging material into MEMS fabrication bridged the gap for devices that are 3-D, meso or large scale, have relatively large force and are low cost.
New Paradigms for Sustainable Society and Industries: Technology Conversion From One Way to Circulation
Authors: Hamada Yasuo , Honda Hiroshi
Published: November 2021

In January 1998, the Vostok project team, under the collaboration between American, Russian and French scientists, discovered and mined an underground ice core of 3,623m deep in the East Antarcitica.1) As a result of the study on this ice core, the climate conditions of the earth for the past four hundred and twenty thousand years came out clearly, as if it were recorded on a magnetic tape, as shown in Figure 1. It can be seen that the data on concentration of CO2, CH4 and temperature among others for this period signal a warning for future activities of the entire humankind of the earth.1)
Successfully Managing the Risk and Development of Your Business and Technology in the Global Economy
Authors: Honda Hiroshi
Published: November 2021

National and regional economies have become increasingly bound to a global economy with the availability of advanced communication, information and transportation technologies among others, while the advancement of science and technology in general has served as a driving engine for economic and industrial development of local and national economies, and subsequently for those of regional and global economies with substantial time lags in the past millennium. The globalization has given a significant impact on each society by accelerating instant and/or speedy flows of information, money, commodity, energy and human beings, and thus has provided increasingly equal opportunities to societies around the globe for the development of business and technology. Nevertheless, characteristics and specific boundary conditions of local areas, nations and regions still characterize the business and technological opportunities for specific communities.

The global constraints such as limitation in natural resources and energy, and the global environmental issues have driven human beings to challenge a huge task for the new and renewable energy development, environmental protection, and development and utilization of space and other frontiers such as deep underground and deep seas, on a global scale of competition and cooperation. Under these circumstances, we will need to manage the risk and development of our business and technology increasingly from global perspectives, with due consideration on the global constraints and specific characteristics of the focused local societies. This paper is intended to set scene and raise issues for discussion at the subject symposium of ours.
Lessons Learned in Forming an Intellectual Property Management Group Within Your Corporation
Authors: Brown Susan Ipri
Published: November 2021

Delphi Technologies, Inc. (DTI) was established January 1, 1999 to actively cultivate and manage Delphi Automotive System’s intellectual property. Delphi Automotive Systems is a world leader in automotive components and systems technology. Delphi currently has thousands of patents in its portfolio and generates hundreds more each year on a wide variety of technologies. Comprised of three groups — Central Research, Licensing, and Intellectual Property Legal Staff — DTI’s mission is to enhance Delphi’s competitive position and to generate revenue from licensing. DTI’s experience in starting operations and establishing itself inside and outside of Delphi provides valuable lessons for any corporation interested in more actively managing and leveraging its intellectual property.
Material Modelling of Sheet Metal by Bi-Axial Loading Tests
Authors: Pijlman Hermen H. , Brinkman J. , Huétink J. , Vegter H.
Published: November 2021

A new material description for sheet metal forming has been developed. The material description exists of the Vegter yield criterion and a physically based hardening rule. In contrast to most former criteria, the Vegter yield criterion is based on measurements of multi-axial yield stress states. The yield criterion is extended with a physically based hardening rule, in which the flow stress depends on the strain and strain rate.

To measure the multi-axial stress states a biaxial test equipment is being designed. The test equipment will be capable of imposing a shear deformation and a plane strain deformation, including combinations of both deformations. To check whether the bi-axial test equipment will give reliable results, a Finite Element model of a part of the test piece and the clamp equipment is constructed.
Methods for Simulation-Based Optimization of Vehicle Handling Behavior
Authors: Schuller Juergen , Haque Imtiaz , Fadel George
Published: November 2021

A global optimization of vehicle properties is currently not possible. In case of vehicle handling behavior, the optimal design parameter combination is dependent on the desired dynamic characteristics; i.e. it is a tradeoff between different objectives. In this paper, three methods are shown, which are crucial for the optimization of vehicle handling in a virtual environment: a multi-objective, multi-scenario optimization method, an approach for prediction of subjective ratings from driver inputs and vehicle reactions and, last but not least, an approach for the modeling of the control behavior of the human driver.
Tank Shape Optimization for Enhancement of Roll Stability of Partially Filled Tank Vehicles in Steady Turning
Authors: Kang X. , Rakheja S. , Stiharu I. , Ahmed A. K. W.
Published: November 2021

A generic tank cross-section is proposed to describe the geometry of road tanks used in transportation of bulk liquids, and to explore optimal tank geometry for enhancement of roll stability limits of partially-filled tank vehicles. Two different constrained optimization functions are formulated to minimize the lateral load shift with prescribed cross-sectional c.g. height, and the liquid load shift and c.g. height simultaneously, subject to constraints imposed on the total capacity, overall width and height, and perimeter. Two optimal tank cross-sections are proposed to achieve minimal overturning moments corresponding to medium and high fill ranges. A static roll plane model of the partially-filled generic tank is developed to study the performance potentials of the optimal tanks in terms of translation of the cargo c.g. within the tanks under various fill volumes and vehicle lateral acceleration, which are then compared with those of the conventional circular and modified-oval cross-sectional tanks. The performance potentials of the proposed optimal tanks are further explored in terms of rollover threshold lateral acceleration limit of a partially-filled articulated tank vehicle combination as a function of the fill volume, using a static roll model of the tank vehicle realized by integration of the steady-state roll plane model of the partially-filled generic tank with that of the vehicle. The results reveal that the magnitude of rollover threshold of the 40–70% filled vehicle with the proposed optimal tank geometry is approximately 10% higher than that with a circular cross-sectional tank, and 13–25% higher than that with a modified-oval tank.
An Injection Molding Expert Controller Based on Neural Network Optimization Schemes
Authors: Wang Pei-Jen , Liang Jui-Ming
Published: November 2021

The objective of this paper is to investigate the optimization schemes for intelligent process control based on neural networks in injection molding. To achieve the goal of intelligent process control, performance indexes, formulating by multi-losses functions, are adaptively optimized for reverse deducing the process control parameters from the quality factors of parts. In addition, the requirements on quality factors such as dimensions, shrinkage, and warpage are predicted by making use of the Computer-Aided Engineering software, namely C-MOLD, with the process window pre-screened by the Design of Experiments procedure. Hereby, a model consisting of Radial Basis Functions Networks (RBFN) is employed for representing the causal factors between the process control parameters and the quality factors. And, the RBFN model is then trained for optimizing the given performance indexes with an adaptive optimization scheme. Finally, two example cases based on numerical simulations on process control are demonstrated for verifications. It is observed that the proposed intelligent process control in injection molding could automatically achieve stable and nearly optimal process conditions within a short period of time for the given quality requirements. Therefore, the intelligent expert controller could be applied for practical uses on the shop floor in the future.
An Investigation of the Effect of Elongational Viscosity on Entrance Flow
Authors: Sarkar Debabrata , Gupta Mahesh
Published: November 2021

A new model for strain-rate dependence of elongational viscosity of a polymer is introduced. The proposed model can capture the initial strain thickening, which is followed by a descent in elongational viscosity as the elongation rate is further increased. Effect of the four rheological parameters in the new model on a 4:1 entrance flow is analyzed. It is confirmed that the entrance pressure loss and recirculating vortices in an entrance flow grow significantly as the Trouton ratio is increased. The center-line velocity near the abrupt contraction in a 4:1 entrance flow is found to overshoot its value for a fully developed flow in the downstream channel, if the Trouton ratio has a local minima beyond the Newtonian limit of the polymer.
Using Computer Simulation as a Process Design Tool for Resin Injection Pultrusion (RIP)
Authors: Ding Zhongman , Li Shoujie , Lee L. James , Engelen Herbert
Published: November 2021

Resin Injection Pultrusion (RIP) is a new composite manufacturing process, which combines the advantages of the conventional pultrusion process and the Resin Transfer Molding (RTM) process. It is sometimes referred to the Continuous Resin Transfer Molding (C-RTM) process. The RIP process differs from the conventional pultrusion process in that the resin is injected into an injection-die (instead of being placed in an open bath) in order to eliminate the emission of volatile organic compounds (styrene) (VOC) during processing. Based on the modeling and simulation of resin/fiber “pultrudability”, resin flow, and heat transfer and curing, a computer aided engineering tool has been developed for the purpose of process design. In this study, the fiber stack permeability and compressibility are measured and modeled, and the resin impregnation pattern and pressure distribution inside the fiber stack are obtained using numerical simulation. Conversion profiles in die heating section of the pultrusion die can also be obtained using the simulation tool. The correlation between the degree-of-cure profiles and the occurrence of blisters in the pultruded composite parts is discussed. Pulling force modeling and analysis are carried out to identify the effect on composite quality due to interface friction between the die surface and the moving resin/fiber mixture. Experimental data are used to verify the modeling and simulation results.
Estimation of Elongational Viscosity Using Entrance Flow Simulation
Authors: Sarkar Debabrata , Gupta Mahesh
Published: November 2021

A new elongational viscosity model along with the Carreau-Yasuda model for shear viscosity is used for a finite element simulation of the flow in a capillary rheometer die. The entrance pressure loss predicted by the finite element flow simulation is matched with the corresponding experimental data to predict the parameters in the new elongational viscosity model. For two different polymers, the predicted elongational viscosity is compared with the corresponding predictions from Cogswell’s analysis and K-BKZ model.
Buckling vs. Crack Growth: Numerical Simulation
Authors: Siegmund T.
Published: November 2021

Thin walled structures are characterized by configurations that possess large aspect ratios, i.e. large in-plane dimensions and small thickness dimensions. The present work aims on investigations of the mechanical integrity of such structures thereby focusing on the competition and interaction between global failure due to buckling and local failure due to crack growth.
Dynamic Response of a Heat Damaged Fiber-Resin Beam Subjected to Harmonic Forcing at the Tip
Authors: Nayeb-Hashemi H. , Harrison A.
Published: November 2021

A cantilever beam built of fiber-resin composite material and damaged by heat is evaluated for its dynamic response using numerical methods. The goal of research is to produce a diagnostic process in which dynamic response can be used to estimate the severity of damage to the beam. Research proceeds from formulation of the continuous media equations for vibration in a multiply segmented beam, to the development of finite element models for the beam. It is discovered that the results of these two methods are qualitatively different from the predictions of a lumped system model, in that the lumped system predicts that frictional damping should reduce the dominant frequency of vibration while the more elaborated models indicate that damping may increase the dominant frequency. It is further discovered that the size and location of damage (the geometry) are equally as important as the local stiffness and damping of the damaged region (the material properties). The results indicate that the dominant frequency of dynamic response is not a sufficient symptom for complete diagnosis of damage in the beam.
Bolt Head Fillet Stress Concentration Factors in Cylindrical Pressure Vessels
Authors: Srinivasan Gowri , Lehnhoff Terry F.
Published: November 2021

Linear three-dimensional finite element analysis (FEA) was performed on bolted pressure vessel joints to determine maximum stresses and stress concentration factors in the bolt head fillet as a result of the prying action. The three-dimensional finite element models consisted of a segment of the flanges containing one bolt, using cyclic symmetry boundary conditions. The flanges were each 20 mm in thickness with 901.7 mm inner diameter. The outer flange diameter was varied from 1021 mm to 1041 mm in steps of 5 mm. The bolt circle diameter was varied from 960.2 mm to 980.2 mm in steps of 5 mm. The bolts used were 16 mm diameter metric bolts with standard head and nut thickness. The threads were not modeled. The internal vessel pressure was 0.6895 MPa (100 psi).

Stress concentration factors in the bolt head fillet were calculated and they ranged from 3.34 to 4.80. The maximum stress in the bolt as well as the stress concentration factors in the bolt head fillet increase with an increase in bolt circle diameter for a given outer flange dimension. Keeping the bolt circle diameter constant, bolt stress and stress concentration factors in the bolt head fillet decrease with increase in outer flange diameter. The maximum stresses in the bolt were also calculated according to the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code and the Verein Deutscher Ingenieur (VDI) guidelines and compared to the results observed through finite element analysis. The stresses obtained through FEA were larger than those predicted by the ASME and VDI methods by a factor that ranged between 2.96 to 3.41 (ASME) and 2.76 to 3.63 (VDI).
Resonant Heat Transfer Enhancement by Acoustic Excitation in a Side-Heated Rectangular Enclosure
Authors: Kim Seo Young , Kim Sung Ki , Kang Byung Ha
Published: November 2021

Resonant transport enhancement by acoustic excitation in a sidewall-heated rectangular enclosure, in which natural convection flow is initially dominant, is considered. The enclosure is made of Plexiglas which dimensions are 30cm in height, 30cm in width and 30cm in depth. One sidewall of the enclosure is heated by an electrical foil heater and the other sidewall is maintained at a cold temperature by a cold water circulation. A woofer speaker is mounted on the bottom wall of the enclosure to generate pressure fluctuation inside the enclosure. All the walls of the enclosure are thermally insulated. The experimental results obtained indicate that there exists a resonant forcing frequency and velocity amplitude, which enhances thermal transport from the heated wall to the cold wall. It is also observed that, at the resonant state, the air temperatures inside the enclosure gather to an averaged air temperature by enhanced flow mixing. The relationship between the resonant frequency and the boundary layer wave along the vertical sidewall is discussed.
Turbulent Flow in Closely-Pitched Internally Enhanced Tubes
Authors: Ravigururajan T. S. , Srinivasan J.
Published: November 2021

General correlations are developed and verified for friction factor and heat transfer coefficients for single-phase turbulent flow in internally augmented tubes, with low pitch to height ratios. Data from existing investigations were collected for a wide range of tube parameters with e/d: 0.01 to 0.2; p/e: < 8; α/90: 0.2 to 1.0, and flow parameters; Re: 2000 to 250,000 and Pr: 0.66 to 37.6. The data were applied to a linear model to get normalized correlations that were then modified to approach smooth tube correlations, as the roughness variables became very small. The correlations predicted 92% of data from an independent study on microfin tubes within ± 30%. For closely-pitched enhanced tubes, the proposed correlations predict heat transfer/friction factor with better overall accuracy and are suitable for different types of internal enhancements. The heat transfer increases with decreasing p/e ratio and increasing helix angle. The effects of roughness height and pitch on both friction and heat transfer are similar to that experienced in traditional enhancement design (p/e > 8).
Development of Improved Corrosion Inhibitors for Ammonia-Water Absorption Heat Pumps
Authors: Hannon C. L. , Gerstmann J. , Mansfeld F. B. , Sun Z. N.
Published: November 2021

This paper describes the initial results of a research project to develop an improved corrosion inhibitor for the protection of carbon steel surfaces of ammonia-water absorption heat pumps and chillers using rare earth metal salt (REMS) compounds. Chromate compounds are currently used as corrosion inhibitors, but they are toxic, environmentally harmful, and their use is being phased out in many localities. An effective corrosion inhibitor is needed to make advanced ammonia-water absorption heat pump and chiller systems practical. Low-temperature screening tests were conducted to evaluate the potential of cerium salts, a class of REMS compounds, to act as an inhibitor for steel in ammonia-water solutions. Successful results from these tests led to high-temperature (HT) testing in an innovative test apparatus, which simulated a range of temperatures, ammonia concentrations, and phases typically found in ammonia-water absorption systems. HT testing further demonstrated the effectiveness of cerium nitrate as a corrosion inhibitor, and suggested that it may outperform the Chromate compounds currently used. An additional outcome of the project was the successful demonstration of a cerium based surface pretreatment procedure, termed cerating, as an additional corrosion protection feature. Cerated surfaces will prevent corrosion of steel surfaces and ammonia decomposition at steel surfaces. These results have lead to the concept of a dual corrosion protection strategy utilizing a cerium based solution inhibitor with a cerating surface pretreatment to prevent both corrosion and ammonia decomposition. This approach is presently being pursued in a more intensive study.
Experimental Characterization of Oil-Refrigerant Two-Phase Flow
Authors: Lacerda V. T. , Prata A. T. , Fagotti F.
Published: November 2021

Several phenomena occurring inside refrigerating systems depend on the interaction between the refrigeration oil and the refrigerant working fluid. Regarding the refrigeration cycle, good miscibility of oil and refrigerant assure easy return of circulating oil to the compressor through the reduction of the oil viscosity. Inside the compressor the lubricant is mainly used for leakage sealing, cooling of hot elements and lubrication of sliding parts. In the compressor bearing systems the presence of refrigerant dissolved in the oil greatly influences the performance and reliability of the compressor due to the outgassing experienced by sudden changes in temperature and pressure resulting in a two-phase mixture with density and viscosity strongly affecting the lubricant characteristics. A general understanding of the oil-refrigerant mixture flow is crucial in developing lubrication models to be used in analysis and simulation of fluid mechanics problems inside the compressor. In the present investigation the refrigeration oil flow with refrigerant outgassing is explored experimentally. A mixture of oil saturated with refrigerant is forced to flow in two straight horizontal tubes of constant diameter. One tube is used for flow visualization and the other is instrumented for pressure and temperature measurements. At the tubes inlet liquid state prevails and as flow proceeds the pressure drop reduces the gas solubility in the oil and outgassing occurs. Initially small bubbles are observed and eventually the bubble population reaches a stage where foaming flow is observed. The flow visualization allowed identification of the two-phase flow regimes experienced by the mixture. Pressure and temperature distributions are measured along the flow and from that mixture quality and void fraction were estimated.
Design and Analysis of a Miniature Reciprocating Compressor Driven by a Comb Drive
Authors: Hao Z. , Kapat J. S. , Chow L. C. , Sundaram K. B.
Published: November 2021

The design and working principle of a miniature reciprocating compressor driven by an electrostatic comb drive is presented and its basic parameters are discussed. The compressor, which is 6 mm in diameter and less than 0.5 mm in thickness, has a simple structure consisting of a compressor chamber, a corrugation diaphragm driven by a vertical comb-drive, and two active micro-valves. Using air as working medium, the simple mechanical system enables a compression ratio of 1.5. With a working voltage of 320V, the device gives flow rates of 2.7 ml/ min. The three-dimensional flow field in the chamber is also simulated using a commercial computational fluid dynamics software.
Intermittent Convective Heat Transfer for Ground-Source Heat Pump Design
Authors: Stevens James W.
Published: November 2021

An accurate estimate of the heat transfer from a buried pipe to the surrounding ground is essential for the design of the ground loop portion of a ground-source heat pump. Exact analytical solutions to this problem are complicated by the fact that heat pump systems rarely operate continuously. Complete numerical simulations of system designs can be carried out, but these are unwieldy and difficult to justify for initial scoping calculations, or for preliminary performance estimates. The purpose of this paper is to describe the development of simple algebraic correlations that can be used to approximate the intermittent overall heat transfer between a fluid flowing in an isolated buried pipe and the surrounding ground.

The correlations described in this paper were drawn from results of a numerical finite-difference analysis of a fluid flowing intermittently in a single round pipe and exchanging heat with the surrounding ground. The two-dimensional analysis was carried out for ranges of the parameters of intermittence factor, thermal diffusivity of the ground, and convective heat transfer coefficient at the fluid-wall interface. The surrounding ground is unbounded for the purposes of the analysis. The dimensionless heat transfer can be easily related to the overall thermal resistance between the flowing fluid and the ground far from the buried pipe.

It is found that the cycle average heat transfer is always lower for the intermittent case than for the continuous case, but that the average over just the active part of the cycle is always higher for any intermittent case than for the continuous case. The effect of the ground thermal diffusivity is largest when the heat transfer coefficient is large, and decreases with decreasing heat transfer coefficient. The range of heat transfer coefficients where isothermal wall conditions are approached is illustrated. Correlations for the operating average and cycle average total heat transfer are presented as functions of the thermal diffusivity, intermittence factor, and heat transfer coefficient.
Air-Side Heat Transfer and Pressure Drop Characteristics of Multi-Louver Fin and Flat Tube Heat Exchangers
Authors: Kim Man-Hoe , Bullard Clark W.
Published: November 2021

An experimental study on the air-side heat transfer and pressure drop characteristics for multi-louvered fin and flat tube heat exchangers has been performed. For 45 heat exchangers with different louver angles (15–29°), fin pitches (1.0, 1.2, 1.4 mm) and flow depths (16, 20, 24 mm), a series of tests were conducted for the air-side Reynolds numbers of 100–600, at a constant tube-side water flow rate of 0.32 m3/h. The inlet temperatures of the air and water for heat exchangers were 21°C and 45°C, respectively. The air-side thermal performance data were analyzed using effectiveness-NTU method for cross-flow heat exchanger with both fluids unmixed. The heat transfer coefficient and pressure drop data for heat exchangers with different geometrical configurations were reported in terms of Colburn j-factor and Fanning friction factor f, as functions of Reynolds number based on louver pitch. Correlations for j and f factors are developed and compared to other correlations.
The Dead State According to the Available Energy of Gibbs
Authors: Paulus David M. , Gaggioli Richard A.
Published: November 2021

For exergy calculations, it is necessary to choose a reference environment. Typically the ambient conditions surrounding the system are chosen. It will be argued here that the outdoor environmental conditions are not always correct as a reference “dead state” for evaluating a system or accounting. The constraints on the system must be considered when choosing this “dead state”. Gibbs’ original available energy concept allows a proper dead state to be chosen, especially when a system has no or only partial interaction with the environment. The application of this theory is demonstrated in this paper through the example of a hypothetical plant, which serves as both a chiller and a heat pump.
Second Law Aspects of Simplified Models for Sensible Thermal Storage
Authors: Homan K. O.
Published: November 2021

This paper presents results for entropy generation during the inflow of a low temperature stream into a sensible thermal storage vessel initially filled with a uniformly high temperature liquid. The level of internal entropy generation due to thermal mixing between the cold and hot liquid corresponds to losses in the usable fraction of the stored volume and therefore decreased efficiency. Empirically, the observed behavior of sensible storage devices spans the range of nearly mixed to well stratified. In this investigation, analytical models for these two limits, the fully mixed and ideally stratified conditions, are used to bound the entropy generation levels of the observed behaviors. A numerical model for stratified storage systems based on the one-dimensional convective energy equation which accounts for aspects of the observed thermal mixing is then examined in relation to the afore-mentioned limits. The results show that even at moderate throughflow rates, the fully mixed and ideally stratified limits are separated by orders of magnitude in terms of entropy generated. The empirically-based numerical model exhibits mixing levels midway between these two limits and thereby underscores the potential for significant improvements in efficiency. Examination of the numerical model shows the crucial importance of resolving the evolution of the interior thermal layer and the boundary heat fluxes in computing the entropy generation.
LO.CO.MO.DIA: Low Cost Monitoring for Diagnostic Purposes of a Small Scale CHP Plant
Authors: Fantozzi Francesco , Desideri Umberto
Published: November 2021

Small scale Internal Combustion Engines (ICE) powered Combined Heat and Power (CHP) plants are economically convenient when availability and efficiencies are above specified limits. Nevertheless these plants are often run without a monitoring device capable of data storing and trending and of performance evaluation.

This paper describes the setting up of a powerful low-cost monitoring system for the CHP plant that powers the School of Engineering of the University of Perugia. Data acquisition is performed by interfacing a Personal Computer (PC) to existing control panels via, serial port, and to a data acquisition board for those variables that are not measured by existing devices. Performance indexes are then calculated via software. Alarms and controls are stored as well to set up a database for diagnostic purposes.

The monitoring itself has already shown its troubleshooting capability in interface to maintenance personnel: history trending of variables speeds up the phase of failure identification because it eliminates those possibilities that are negated by cross referencing values of different variables.
Performance and Emission Analysis of a Variable Load Operated Gas Turbine
Authors: Bozza Fabio , Cameretti Maria Cristina , Marro Antonio , Tuccillo Raffaele
Published: November 2021

The authors present a methodology for the prediction of performance and emissions of a gas turbine under a wide range of load conditions. The engine, of the aero-derivative type, is employed in a natural gas recompression plant.

The paper deals, in its first part, with the reconstruction of the whole operating region of both the gas generator set and the power turbine including its matching with the centrifugal compressor for natural gas delivery in the pipeline. This phase also leads to an effective prediction of pollutant emission, with a chemical kinetics based sub-model.

Next, a refined CFD based simulation analyzes a number of operating cases, so providing a detailed insight of the actual phenomena which control the combustion chamber temperature distribution and the activation of the pollutant formation mechanisms.
Parametric Analysis of a Thermally Actuated Cooling System for Space Applications
Authors: Freudenberg K. , Lear W. E. , Sherif S. A.
Published: November 2021

Integration of new and existing technologies for thermal management will be required to meet the challenges associated with the increased need for an efficient, lightweight, heat rejection system. Subsystem design requirements, such as thermal and mass management, must be brought into me design cycle to establish an optimal configuration. This paper provides a parametric analysis that determines a range of parameters under which a proposed system becomes viable from a weight management standpoint. The analysis can be applied to essentially any space-operated thermally-actuated heat pump with power and refrigeration subsystems. By applying the techniques demonstrated in this paper, designers can identify and optimize conceptual configurations during the initial prototype development stages to reduce payload weight and increase financial savings.
Investigation of a Novel Gas Turbine Cycle With Coal Gas Fueled Chemical-Looping Combustion
Authors: Jin Hongguang , Ishida Masaru
Published: November 2021

A new type of integrated gasification combined cycle (IGCC) with chemical-looping combustion and saturation for air is proposed and investigated. Chemical-looping combustion may be carried out in two successive reactions between two reactors, a reduction reactor (coal gas with metal oxides) and an oxidation reactor (the reduced metal with oxygen in air). The study on the new system has revealed that the thermal efficiency of this new-generation power plant will be increased by approximately 10–15 percentage points compared to the conventional IGCC with CO2 recovery. Furthermore, to develop the chemical-looping combustor, we have experimentally examined the kinetic behavior between solid looping materials and coal gas in a high-pressure fixed bed reactor. We have identified that the coal gas chemical-looping combustor has much better reactivity, compared to the natural gas one. This finding is completely different from the direct combustion in which combustion with natural gas is much easier than that with other fuels. Hence, this new type of coal gas combustion will make breakthrough in clean coal technology by simultaneously resolving energy and environment problems.
Prediction of Radiative Heat Transfer in a 2D Enclosure With Blocked-Off, Multi-Block, and Embedded Boundary Treatments
Authors: Byun Do Young , Baek Seung Wook , Kim Man Young
Published: November 2021

A prediction of radiative heat transfer in a complex geometry was performed using different boundary treatments such as blocked-off, spatial-multiblock, and embedded boundary methods. The formulation of embedded boundary treatment for finite volume was derived here. The finite-volume method (FVM) was used to model the radiative transfer in an absorbing and emitting medium which is maintained at an isothermal condition and enclosed by cold and black walls. While the body-fitted grid system was used for the spatial multi-block treatment, the Cartesian grid system was chosen for the others. Their results were compared and discussed for three different cases including trapezoidal enclosure, semi-circular enclosure with internal block, and incinerator-shaped enclosure. The accuracy obtained by application of each treatment was shown to be highly satisfactory. Consequently, each treatment was suitable for modeling the radiative heat transfer in the complex geometry. However, the solution obtained by the blocked-off treatment has yielded some errors compared with the others, since the Cartesian grid used in the blocked-off treatment could not exactly configure the complex boundaries. Especially, the radiative heat flux on the non-orthogonal wall was largely underestimated due to its stepwise description of the wall.