bluuebunny/crossref_metadata_2025 huggingface dataset:
A Sustainable Approach to Advanced Energy and Vehicular Technologies at the University of Kansas
Authors: Depcik Christopher , McKown Lou , LeGresley Matt
Published: July 2010

In the fall of 2008, the Department of Mechanical Engineering at The University of Kansas began a hybrid vehicle program as an undergraduate senior design project. The purpose of this class is to ensure that the students leaving the curriculum are learning about advanced energy and vehicular technologies to make them attractive candidates for the new wave of energy related jobs. Future efforts of this project will follow the pathway of the Department of Energy’s Strategic Approach to Energy Security while keeping objectives realistic and costs manageable. From the first meetings with the students, a sustainable architecture was set as the approach to the project. The student’s definition of sustainability draws from others mentioned in the literature and illustrates the application of engineering techniques to solving real-world problems by holistically approaching the situation from five vectors of success: the environment, energy, economics, education and ethics. Each of these concepts individually addresses specific aspects of sustainability, shaped by the confluence of the ideals of people, planet, and prosperity. Moreover, it is through the multi-leveled application of the vectors of success that the students have developed the means to face the challenges of advanced hybrid automotive technologies. This paper describes the hurdles faced by the faculty and students upon starting this hybridization program, illuminating methods to minimize the costs involved with beginning a new vehicular program while maximizing the reward to the students and faculty. In particular, the recycling of an iconic vehicular platform, the Volkswagen Super Beetle, has stimulated enthusiasm in the program while also providing a reasonable baseline vehicle. In addition, the reclamation of such a vehicle is inherently economically and environmentally friendly. This has significantly reduced the start-up expenses of the project by taking advantage of a discarded and underutilized resource. Since a hybrid vehicle is a complex electro-mechanical and aerodynamic system, the success of the program ultimately relies upon building relationships with faculty members across many disciplines. As a result, this paper illustrates novel methods of synergy in order to exemplify how multiple disciplines can work independently, yet with a common goal. Furthermore, this work describes the inclusion of energy technologies often not associated with production vehicles, such as solar and wind power. Finally, the authors demonstrate how the five vectors of sustainability fit within the program to ensure continuing success of the curriculum.
The Thermal Performance of Graphite Heat Spreaders in Radiant Panel Applications
Authors: Smalc Martin D. , Norley Julian , Schober John , Reynolds R. Andrew , Reis Brad
Published: July 2010

Hydronic radiant floor heating systems are recognized as an efficient means of heating residential and commercial buildings. These systems utilize water flowing in tubes to move thermal energy from a heat source to a radiant panel located beneath the floor of the room being heated. The efficiency of such systems depends on many factors but a major concern is the ability of the radiant panel to remove heat from the water tubes and spread it effectively across the floor. Conventional radiant panels use aluminum heat spreaders to do this. Much work has been done to determine the overall performance of rooms heated by radiant panels, but little work has been done to measure the thermal performance of heat spreaders in these panels. This paper describes the development of a test method, using thermal imaging of test panels, to measure the performance of these heat spreaders. This method is used to determine the thermal performance of commercially available aluminum heat spreaders and of advanced heat spreaders made from flexible graphite. Graphite heat spreaders have found wide acceptance in a variety of electronic applications including plasma and LED displays, laptop computers and cell phones. This paper also examines the thermal properties of graphite that make it attractive as a radiant panel heat spreader. The development of high thermal conductivity, flexible graphite spreaders for various radiant panel applications is described. These graphite heat spreaders improve the performance of radiant panel systems and allow the use of high efficiency, low temperature heat sources.
Hydrothermal Conversion of Cattle Manure to Biooil: Effects of Conversion Parameters on Biooil
Authors: Yin Sudong , Dolan Ryan , Tan Zhongchao
Published: July 2010

Due to intensive feedlots operations, the role of cattle manure has changed from a cheap fertilizer to an agricultural waste. Hydrothermal conversion (HTC) is a potential technology of converting cattle manure waste to biooil. In this paper, HTC of cattle manure was studied with regards to the effects of conversion temperature, pressure, residence time, process gas and mass ratios of cattle manure to water on yields and properties of biooil. Results showed that within the temperature range of 260 ∼ 360 °C, biooil yield first increased and then decreased. The maximum biooil yield was obtained at 310 °C. The biooil yield was not further improved by higher initial operating pressure. In contrast, it decreased biooil yields from 38.49% under 0 psig to 6.51% under 150 psig. Longer residence times also reduced biooil yield. Compared with 38.49% of biooil produced with 15-minute residence time, only 12.95% of biooil remained after 40-minute residence time. Process gases also had important impacts on biooil yield. When N2 was replaced with CO, the maximum biooil yield increased to 48.76%. But, when air was used as process gas, the biooil yield decreased to 27.97%. Also, biooil yield decreased with larger mass ratios of cattle manure to water. When the ratio was 2, biooil yield was only 1.46% much less than 48.76% with ratio of 0.25. Therefore, biooil yield from HTC of cattle manure largely depended on the conversion temperatures and process gases. Higher conversion pressures, longer residence time and larger mass ratios of cattle manure to water had negative impacts on biooil yield. The mean high heating value of biooil from HTC of cattle manure was 37.0 MJ/kg.
Application of LCP Contact Formulation on Mechanical Systems With Nonrigid Coupled Unilateral Contact Points Illustrated With a Simple Model of a Windscreen Wiper
Authors: Tatzko S. , Gro¨nefeld P. , Wangenheim M.
Published: July 2010

Technical applications with unilateral contact are often modeled as multiple coupled discrete mass points. The transition between contact states is often described by transforming the contact formulation into a linear complementary problem (LCP). In case of compliant materials such as rubber, the LCP can be simplified so that no algorithm is needed to solve the equation system. Thus, computational effort can be reduced considerably. In this paper a windscreen wiper lip is modeled as a simple mechanical system with unilateral contact points. The system consists of masses which are coupled by linear springs and dampers. The masses can come into contact with a rigid surface. The equations of motion are derived and transformed into an LCP. The modeling of the coupled, compliant system leads to a simplification of the equation system. Therefore, it can be solved line by line as single independent scalar LCP’s. Also at the transition from separation to contact, when an impact occurs, the contact points can be considered individually. It will be shown, that the coupling can be neglected during the infinitesimal small time of impact. The LCP formulation in combination with simple models of compliant structures therefore yields an effective method for treating multibody systems or discretized continua with several unilateral contact points.
The Network Locating Principle in Flexible Circuit Board Assembly
Authors: Chen Ruijun
Published: July 2010

This paper focuses on developing the Network Locating Principle for fixturing tooling design in flexible circuit board assembly. From a viewpoint of Thermodynamics, a flexible circuit board populated with electronic components on the first side is a closed thermodynamic system. It experiences deformation energy change, assembly load work, and heat transfer during an isothermal assembly process on the second side, such as solder paste deposit printing and electronic component placement processes. Based on the First and Second Laws of Thermodynamics and Energy Equation of Thermoelastic Theory, a fixturing analysis is developed to investigate the deformation energy change, and furthermore the theoretical fixturing solution is derived to minimize the assembly load work during the isothermal assembly processes. To this end, the Network Locating Principle is proposed to guide fixturing tooling design for the isothermal assembly processes on the second side. Effectiveness of the Network Locating Principle is verified in numerical and experimental studies of flip chip placement processes on a thin flexible circuit.
Investigation of Heat Pipe Cooling in Drilling Applications: Part 2—Thermal, Structural Static, and Dynamic Analyses
Authors: Zhu Lin , Jen Tien-Chien , Yin Chen-Long , Yen Yi-Hsin , Zhu Mei , Zhang Jianhua
Published: July 2010

Drilling is a highly complex machining process coupled with thermo-mechanical effect. Both the rapid plastic deformation of the workpiece and the friction along the drill-chip interface can contribute to localized heating and increasing temperature in the workpiece and tool. The cutting temperature at the tool-chip interface plays an important role in determining the tool thermal wear. This in turn affects the dimensional accuracy of the workpiece and the tool life of drill. A new embedded heat pipe technology has been proven to be able to effectively not only remove the heat generated at the tool-chip interface in drilling, but also minimize pollution and contamination of the environment caused by cutting fluids. Less tool wear can then be achieved, thus prolonging the tool life. 3D Finite Element method using COSMOS/works is employed to study coupled effects of thermal, structural static and dynamic analyses in a drilling process to check the feasibility and effectiveness of the heat pipe drill. Four different cases, solid drill without coolant, solid drill with coolant, heat pipe drill, and heat pipe drill with coolant, are explored, respectively. The results from this study can be used to define geometric parameters for optimal designs.
A Model to Predict Pore Shape in Solid During Solidification
Authors: Hsiao S. Y. , Wei P. S.
Published: July 2010

The shapes of a growing or decaying bubble entrapped by a solidification front are predicted in this work. The bubble results from supersaturation of a dissolved gas in the liquid ahead of the solidification front. Pore formation is one of the most serious issues affecting properties, microstructure, and strength in materials. In this study, the bubble entrapped as a pore in solid are realistically predicted by utilizing perturbation solutions of Young-Laplace equation governing the tiny bubble shape in the literature. The analytical solutions can account for necking of a bubble beyond the solidification front. Satisfying energy, momentum, mass conservation and physico-chemical equilibria on the bubble surface, the predicted time-dependent pore shapes are found to agree with in-situ measurements.
Feasibility of Team-Based Learning Techniques in a Large Engineering Course
Authors: Joo Sung-Hwan
Published: July 2010

This paper describes the feasibility of team-based learning techniques in a large engineering course and reviews the team-based learning. First, the problems which instructors are facing when they teach the large class are discussed. Then, several active learning methods are briefly introduced and reviewed. The team-based learning concept will be reviewed and advantages of team-based learning in a large engineering class are discussed at the latter part of the paper.
Modeling of Ultrashort Pulse Laser Ablation in Water
Authors: Jiao Jian , Guo Zhixiong , Mitra Kunal
Published: July 2010

A numerical model combining the ultrafast radiative heat transfer and ablation rate equation for free electron density is proposed to investigate the transient process of plasma formation in distilled water. The focused beam propagation governed by the transient equation of radiative heat transfer is solved by the transient discrete ordinates method. The temporal evolution of free electron density governed by the rate equation is solved using a forth-order Runge-Kutta method. Two laser pulses: 30 ps and 300 fs are considered. Simulation of the dynamics of plasma formation is performed. The results include the threshold laser intensity for optical breakdown, temporal evolution and spatial distribution of the free electron density as well as the maximum plasma length. To validate the model, optical breakdown thresholds for different laser pulses, the shape of plasma breakdown region and the maximum plasma length predicted by the present model are also compared with the experimental data.
Temperature Measurement in High Speed Cylindrical-Plunge Grinding Using Thermocouple
Authors: Zhu Dahu , Li Beizhi , Pang Jingzhu , Yang Jianguo , Zhang Dan
Published: July 2010

Temperature measurement is employed for research in grinding and for process monitoring. Because of the difficulty in arrangement of thermocouples, temperature measurement in grinding presents a number of challenges, particularly in high speed cylindrical-plunge grinding. Based on existing literature, only one thermocouple is considered for measuring the maximum temperature in the grinding contact arc, without considering the overall temperature variation. In this paper, a new measurement method, named four K-type thermocouples are proposed aslant along the direction of the width of workpiece which is developed for measuring the overall contact arc in high speed cylindrical-plunge grinding. It is shown that the temperature increases to the maximum with a sharp gradient, then decreases due to the strengthening of cooling effect and the decrease of depth of cut, which is consistent with previous study. The measured temperature signal reveals the generation rule and dissipation rule of grinding heat. The influence of grinding parameters on the temperature is also discussed in detail in the paper.
Comparison of Rankine Cycles for Micro-CHP Generation Based on Inward Flow Radial Turbine or Scroll Expander
Authors: Casarsa Luca , Mucignat Claudio , Reini Mauro
Published: July 2010

This contribution aims to analyze micro-CHP units based on Rankine cycles. Two types of expander are considered: a small scale inward flow radial turbine and a volumetric scroll type expander. This latter, should allow to overcome the limitation imposed by a standard steam-turbine that arise when the required shaft-power is very low. Moreover, the scroll expander will also allow to easily treat wet steams, which must be avoided when considering a turbo-expander. The final aim is to deduce which one of the two types of expander is more suitable, with a specified target performance and the availability of a certain hot source. In order to define the thermodynamic expansion process, the analysis uses a one-dimensional model of the radial turbine, previously developed by the authors, and of an estimation of the scroll expander efficiency. Also, the analysis is carried out for different working fluids, such as water, and two organic fluids, cyclohexane and toluene. Through the discussion of the results, for a specified set of constraints (e.g. expander inlet temperature, temperature of condensation, expander geometrical parameters) it is possible to deduce important indications on the most suitable expander for a given cycle layout.
Unsteady Loading of Rotor Blades by High Pressure Air Injection
Authors: Chi John N.
Published: July 2010

A gas turbine engine consists of three primary components: a compressor, a combustion chamber, and a turbine. The operating range, performance, and reliability of gas turbine engines are limited by aerodynamic instabilities that occur in the compressor at low mass flow rates. Two of such compressor instabilities are rotating stall and surge. The stabilization of compression systems by means of active control has been demonstrated on several research compressors using different actuators such as inlet guide vanes, bleed valves, and air injection to manipulate the compressor flow field. This paper presents experimental and model simulated results of the steady and unsteady behaviors of air injection in high speed axial flow compressors that can be used for feasibility studies and control algorithm development. A control oriented model of the unsteady response of the transonic compressor blade rows to steady air injection is presented. This behavior was modeled by one-dimensional flow in a diffusing passage subject to a time varying inlet flow condition in the rotor relative reference frame. The one-dimensional model was then used to provide simplified input boundary conditions for a computational fluid dynamic (CFD) model that predicted aerodynamic loading on a transonic rotor blade due to steady air injection. The aerodynamic loading on a transonic rotor blade due to steady air injection were then simulated from the computational fluid dynamic (CFD) model. The simulation results for an evenly circumferentially spaced discrete number of jet actuators show that the fluctuating loading due to jet injection are non-sinusoidal and periodic. Total pressure, total temperature, and absolute flow angle survey measurements that map out the effect of high pressure air injection on a transonic compressor rotor for different levels of steady injection and different orientations are also presented.
Precision Grasping With Variable Compliance Using Force Sensing Resistors
Authors: McKay Mark J. , Jenkins Hodge E.
Published: July 2010

The ability to precisely control the applied force and deformation of a grasped object is the focus of this paper. A simple mechanical end effector system with parallel grippers was developed to study compliance effects in precision grasping. A servo gripper was instrumented with force and position sensors, associated circuitry, hardware, and visual indicators; moreover, the sensors and servo motor were connected to a microcontroller that interfaced with a laptop computer. A closed-loop position control system was embedded within a force control system. Springs of varying, known stiffness were grasped to characterize and calibrate the force control system. Compliance effects of the servo gripper were observed and measured while grasping these springs under several discrete control conditions. Experimental data were compared to reduced order theoretical models for validation. A control scheme was successfully developed to precisely grasp and hold objects of varying size, shape, stiffness, and orientation, using the real-time data to establish correction factors for compliance and sensor drift. It was demonstrated that these effects can be minimized by modifying the motor control signals using the presented force and position feedback scheme.
Simple Models for Laminar Thermally Developing Slug Flow in Non-Circular Ducts and Channels
Authors: Muzychka Y. S. , Walsh Edmond , Walsh Pat
Published: July 2010

Solutions to the classical Graetz slug or plug flow problem in non-circular ducts are examined. These solutions have applications where a constant uniform velocity distribution exists across a channel or duct. These are most often realized in the laminar flow of low Prandtl number liquids, such as liquid metals, and low Reynolds number flows through porous media. Expressions are developed for a number of applications using the asymptotic correlation method of Churchill and Usagi. These expressions vary depending on the definition used for the dimensionless heat transfer coefficient in the case of constant wall temperature boundary condition (T), and the dimensionless wall temperature for the constant flux boundary conditions, (H) and (H1). Finally simple expressions are developed for predicting the thermal entrance length and fully developed flow Nu values for non-circular ducts.
Asymptotic Generalizations of the Lockhart-Martinelli Method for Two Phase Flows
Authors: Muzychka Y. S. , Awad M. M.
Published: July 2010

The Lockhart-Martinelli method for predicting two phase flow pressure drop is examined from the point of view of asymptotic modelling. Comparisons are made with the Lockhart-Martinelli method, the Chisholm method, and the Turner-Wallis method. An alternative approach for predicting two phase flow pressure drop is developed using superposition of three pressure gradients: single phase liquid, single phase gas, and interfacial pressure drop. This new approach allows for the interfacial pressure drop to be easily modelled for each type of flow regime such as: bubbly, mist, churn, plug, stratified, and annular, or based on the classical laminar-laminer, turbulent-turbulent, laminar-turbulent and turbulent-laminar flow regimes proposed by Lockhart and Martinelli.
Investigation of the Feasibility and Feedstock Management Strategies of a Flexible Biomass to Ethanol Plant via Process Simulation
Authors: Kou Nannan , Zhao Fu
Published: July 2010

Current US transportation sector mainly relies on liquid hydrocarbon derived from petroleum oil and about 60% of the petroleum oil consumed is from areas where supply may be disturbed by regional instability. This has led to serious concerns on global warming and energy security. To address these issues, numerous alternative energy carriers have been proposed. Among them, second generation biofuel is one of the most promising technologies. Gasification based thermo-chemical conversion can utilize a wide range of biomass wastes and residues and bring flexibility to both feedstock and production sides of a plant, thus presents an attractive technical route. In this paper, a flexible feedstock thermo-chemical ethanol production process is investigated. This research focuses mainly on the evaluation of the feasibility of the process through numerical simulation. An existing thermo-chemical ethanol production model developed by NREL has been updated to handle the cases when different biomass feedstock and feedstock combinations are used. It is found that the ethanol yield is positively proportional to the feedstock feeding rate, while the total conversion efficiency is negatively proportional to the feeding rate. To demonstrate a feedstock management strategy, a plant located near a major city with a population of 200,000 and above is considered and MSW, legume straw and wood chips are selected as potential feedstock. Simulation results indicate that with wood chips as the backup feedstock the plant can be operated under extreme conditions when legume straw availability is significantly reduced without major equipment modification.
The Rigorous Application of FMEA to a Wastewater Treatment Plant Aerator Drive: Understanding Requirements, Conditions, Limitations, and Success Factors
Authors: Tanaka Tomoki , Rosseljong Daniel J.
Published: July 2010

Any supplied gearbox performing below a user’s clearly defined expectations can be viewed as a failure. This case study involves consistent lubricant leakage starting almost immediately after installation. Through various field inspections, modifications and a factory rebuild, the problem was not resolved to the owner’s satisfaction until replaced by (2) new units. This paper documents the factual elements of an engineering evaluation of a gearbox removed from an aerator drive at a wastewater treatment facility, using FMEA [Failure Modes and Effects Analysis] over FTA [Fault Tree Analysis]. The gearbox supplier chose FMEA because it considers the importance of the gearbox components, weighting them to the application, where FTA is often a pure top-down analytical engineering approach without consideration for external factors. The gearbox supplier performed a detailed disassembly of the gearbox under controlled conditions and inspected each gearbox component to identify any faults in material or designs focusing on those that affect the user. The goal of this analysis is to provide a technical understanding of the cause(s) of failure, its consequences, and a means to correct any problems with the gearbox, real or perceived.
A Study Numerical Simulation of Post Combustion CO2 Capture Process
Authors: Chavez Rosa-Hilda , Guadarrama Javier de J. , Hernandez-Guerrero Abel
Published: July 2010

Amine absorption technology, in particular that based on the Monoethanolamine (MEA) process, is considered to be viable for low pressure flue gas CO2 capture because of the MEA-CO2 fast reaction rate. MEA absorption processes are associated with high capital and operating cost because a significant amount of energy is required for solvent regeneration and severe operating problems are present such as corrosion and solvent loss and degradation. The overall objective of this study is to evaluate the feasibility of obtaining the heat required for amine absorption for a particular recovery of carbon dioxide. Comparisons among cases were performed to determine the best operating conditions for CO2 capture. An analysis of the lean loading and recovery percent were carried out as well as the different absorber and stripper combinations by using the chemical processes simulator.
Development and Integration of Engine Simulation Projects Into the Mechanical Engineering Curriculum at Missouri S&T
Authors: Vudumu Shravan K. , Koylu Umit O.
Published: July 2010

The main objective of this paper was to report the development of instructional engineering projects and necessary tutorials that utilize the GT-POWER software for engine simulations in combustion-related courses at Missouri S&T as part of the Partners for the Advancement of Collaborative Engineering Education (PACE) program. Students teamed up to perform modeling of engine performance and emission characteristics so that they could learn state-of-the art engine technology and explore innovative design procedures routinely employed by the leading automotive companies. The projects included understanding and comparison of simple hand calculations using typical textbook assumptions with detailed and complicated software calculations. Such projects would help to bridge the gap between the theoretical and simple concepts learned by students in the classroom and the practical and advanced skills desired by industry. Various tools available for studying engine combustion fueled by alternative fuels were also introduced.
Velocity Analysis of a Compliant Platform
Authors: Correa Julio , Crane Carl
Published: July 2010

In a previous work a compliant microplatform was proposed. The device is formed by the following elements: the actuators, a central moving platform and compliant joints. The actuators are three sets of compliant beams able to support upward deflections. The moving platform is an equilateral plate. Springs connect the free end of each set of actuators with each vertex of the central platform, in this way the motion of the actuators is transmitted to the moving platform. This configuration is specially appropriated for micromanufacturing since current techniques do not permit the fabrication of reliable rigid joints. Compliant joints increase the complexity of the motion of the central platform and few studies have been carried out. This paper focuses on the derivation of equations that relates the velocity of the moving platform with the velocity of the actuators.
Indentation Size Effect on the Hardness of a Sn-Ag-Cu Solder
Authors: Han Y. D. , Jing H. Y. , Nai S. M. L. , Tan C. M. , Xu L. Y. , Wei J.
Published: July 2010

In the present study, nanoindentation studies of the 95.8Sn-3.5Ag-0.7Cu lead-free solder were conducted over a range of maximum loads from 20mN to 100mN, under a constant ramp rate of 0.05s−1. The indentation scale dependence of hardness was investigated. The results revealed that the hardness is dependent on the indentation depth. As the maximum holding load increased, which corresponded to an increasing indentation depth, a decreasing trend in the hardness was observed.
Variational Formulation of Vibrations of Multi-Walled Carbon Nanotubes With Geometric and Physical Nonlinearities
Authors: Adali Sarp
Published: July 2010

Variational principles are derived for multi-walled carbon nanotubes (CNT) undergoing nonlinear vibrations. Two sources of nonlinearity are considered in the continuum modeling of CNTs with the Euler-Bernoulli beam model describing the dynamics of the CNTs. One source is the geometric nonlinearity which may arise as a result of large deflections. The second source is due to van der Waals forces between the nanotubes which can be modeled as a nonlinear force to improve the accuracy of the physical model. After deriving the applicable variational principle, Hamilton’s principle is given. Natural and geometric boundary conditions are derived using the variational formulation of the problem. Several approximate and computational methods of solution such as Rayleigh-Ritz and finite elements employ the variational formulation of the problem and as such these principles are instrumental in obtaining the solutions of vibration problems under complicated boundary conditions.
Experimental Study of Thermal Effects in a Hydrogen Cryo-Adsorption Storage System
Authors: Aleksic´ Petar , Næss Erling
Published: July 2010

While the main barrier for the development of hydrogen adsorption type storage systems remains the material development, an improved thermal management may offer solutions to minimize the penalties in the amount of stored gas during fast-filling and the residual amount of hydrogen during discharging operations. The emphasis of this work was to experimentally investigate the dynamical thermal behavior of a hydrogen cryoadsorption storage system during fast-filling operations. The experiments were conducted with granulated activated carbon and MOF adsorbents. The influence of the charge pressure and the gas flow rate on the temperature elevations and the amount of filled hydrogen gas was analyzed. The heat generated in the storage vessel originates from the released heat of adsorption, gas compression work and thermal energy transfer that takes place when high pressure gas at the ambient temperature is introduced to the tank. A typical average temperature increase observed during the charging of the test tank, filled with the activated carbon (NORIT R0.8 extra), to 2 MPa was about 21 K. Such temperature elevation leads to a significant decrease in adsorption storage capacity.
Hydrothermal Gasification of Waste Biomass Under Alkaline Conditions
Authors: Dolan Ryan , Yin Sudong , Tan Zhongchao
Published: July 2010

Hydrothermal gasification is a promising technology for the treatment of wet organic biomass, and as such, has been subject to significant research effort. It is well known that two groups of catalysts exhibit high activity for hydrothermal gasification—broadly classified as platinum group metals and alkali salts. In the present work, this effect is further investigated through a study of the synergistic effects of sodium carbonate and Pt/Al2O3 on gas yield from cellulose at 315°C. Results indicate that dilute alkali appears far more efficient in promoting gasification reactions in the presence of Pt/Al2O3. Potential mechanisms and a comparison with the alkaline degradation pathways of glucose are discussed.
Periodicity and Nonlinearity of Nonlinear Dynamical Systems Under Periodic Excitation
Authors: Han Lu , Dai Liming , Zhang Huayong
Published: July 2010

Periodicity and nonlinearity of nonlinear dynamic systems subjected to regular external excitations are studied in this research work. Diagnoses of regular and chaotic responses of nonlinear dynamic systems are performed with the implementation of a newly developed Periodicity Ratio in combining with the application of Lyapunov Exponent. The properties of the nonlinear dynamics systems are classified into four categories: periodic, irregular-nonchaotic, quasiperiodic and chaotic, each corresponding to their Periodicity Ratios. Detailed descriptions about diagnosing the responses of the four categories are presented with utilization of the Periodicity Ratio.
Numerical Modeling of Liquid Piston Gas Compression
Authors: Piya Cecil , Sircar Indraneel , Van de Ven James D. , Olinger David J.
Published: July 2010

Prior research has shown that the use of liquid-pistons in place of conventional solid pistons within gas compression technologies can significantly improve the efficiency of gas compression. The liquid-piston provides the prospect for a consistent and high rate of heat extraction from the compressed gas during system operation. Consequently, the input power requirements during each individual compression are lowered. To validate this concept, analytical studies of the thermal-fluids and heat transfer mechanisms during gas compression were performed. The analysis involved the development of a numerical model, using the finite-difference method, which simulated a single compression stroke and quantified the crucial parameters during compression. This model was utilized to obtain theoretical efficiency values and to recognize optimal system characteristics. The results obtained from the simulation indicated double-digit increase in efficiency with the introduction of the liquid-piston.
Experimental Investigation on Onset of Nucleate Boiling in Tube-Bundle Channels
Authors: Lu Guangyao , Ren Junsheng , Zhao Guisheng , Xiang Wenyuan , Ai Huaning
Published: July 2010

Experiments are carried out to investigate the Onset of Nucleate Boiling (ONB) of refrigerant R-113 through vertical and inclined tube-bundle channels. Several methods are adopted to ascertain ONB in the experiments, and their differences are analyzed. The experiments show that the results of ONB estimation from the visualization experiment, ONB estimation from the wall temperature and that from the heat transfer coefficient are uniform. The influences of heat flux, mass flow rate, the geometric dimensions and inclination angle of the tube-bundle channels on the ONB height are explored in detail. On the foundation of the comparisons and analyses, an equation is put forward for calculating the ONB height in tube-bundle channels, which has a good accordance with the experimental results.
Stochastic Response of Structures With Uncertain-but-Bounded Parameters
Authors: Muscolino Giuseppe , Sofi Alba
Published: July 2010

The uncertainty plays an important role in structural engineering. It is largely recognized that the uncertainty may affect both external excitations and structural parameters. However, while the numerous available data permit to model with good accuracy the excitations as stochastic processes, unfortunately the data about the structural parameters are quite limited. It follows that the probabilistic approach cannot be realistically applied to represent structural uncertainties; indeed, it requires a wealth of data, often unavailable, to define the probability distribution density of the fluctuating structural parameters. Non probabilistic approaches can be alternatively used to treat these uncertainties. In this framework, the interval model seems today the most suitable analytical tool. The aim of this paper is to evaluate the range of the random response of linear structural systems, with slight variation of the uncertain-but-bounded parameters, subjected to stochastic Gaussian excitations by applying the so-called interval perturbation method.
Position Control of a Pneumatic Servo System Using Sliding Mode Control and Fuzzy Control: A Comparison
Authors: Dhami S. S. , Bhasin S. S. , Mahapatra P. B.
Published: July 2010

The performance comparison of fuzzy logic control and sliding mode control for position control of a pneumatic actuator for different operative conditions is presented in this article. A virtual model of a pneumatic actuation system is developed using comprehensive mathematical model of the system. A fuzzy logic controller and a sliding mode controller are developed for positioning the piston at different linear displacements for different loading conditions. The virtual model is employed for obtaining the transient and steady state positional response of the pneumatic actuator by implementing the two controllers one by one. The results show that fuzzy controller results in better piston positional response for combinations of lower payloads and smaller linear displacements, whereas sliding mode controller is more effective for combinations of higher payloads and larger displacements.
Modeling and Inverse Design of Convective Heat Transfer in a Grooved Channel Using Proper Orthogonal Decomposition
Authors: Gunes Hasan , Cadirci Sertac
Published: July 2010

In this study we show that the POD can be used as a useful tool to solve inverse design problems in thermo-fluids. In this respect, we consider a forced convection problem of air flow in a grooved channel with periodically mounted constant heat-flux heat sources. It represents a cooling problem in electronic equipments where the coolant is air. The cooling of electronic equipments with constant periodic heat sources is an important problem in the industry such that the maximum operating temperature must be kept below a value specified by the manufacturer. Geometric design in conjunction with the improved convective heat transfer characteristics is important to achieve an effective cooling. We obtain a model based on the proper orthogonal decomposition for the convection optimization problem such that for a given channel geometry and heat flux on the chip surface, we search for the minimum Reynolds number (i.e., inlet flow speed) for a specified maximum surface temperature. For a given geometry (l = 3.0 cm and h = 2.3 cm), we obtain a proper orthogonal decomposition (POD) model for the flow and heat transfer for Reynolds number in the range 1 and 230. It is shown that the POD model can accurately predict the flow and temperature field for off-design conditions and can be used effectively for inverse design problems.
Laminar Flow Forced Convection Heat Transfer Behavior of a Phase Change Material Fluid in Microchannels
Authors: Kondle Satyanarayana , Alvarado Jorge L. , Marsh Charles , Kessler Dave , Stynoski Peter
Published: July 2010

In this paper, a PCM fluid is compared with pure water as heat transfer fluid. The heat transfer behavior of phase change material fluid (PCM) under laminar flow conditions in circular and rectangular microchannels was studied numerically. As part of the numerical study, an effective specific heat technique was used to model the phase change process. Heat transfer results for smooth circular and rectangular microchannels with PCM fluid were obtained under hydrodynamically and thermally fully developed conditions. A PCM fluid in microchannels with different aspect ratios was found to exhibit unique thermal behavior which could be beneficial in electronic cooling applications. As a part of boundary conditions, the flow was assumed to be hydrodynamically fully developed at the inlet and thermally developing inside the microchannel. Heat transfer characteristics of PCM slurry flow in microchannels of various aspect ratios have been studied under three types of wall boundary conditions including constant axial heat flux with constant peripheral temperature (H1), constant heat flux with variable peripheral temperature (H2), and constant wall temperature (T) boundary condition. Effects of phase change on the heat transfer were determined using a specific heat model, which includes the effect of latent heat of fusion of the phase change material. The fully developed Nusselt number was found to be higher for H1 than for H2 and T boundary conditions for all the geometries.
A Combined Rarefied and Continuum Flow Regime Model for Physical Vapor Deposition (PVD) Manufacturing Processes
Authors: Gott Kevin , Kulkarni Anil K. , Singh Jogender
Published: July 2010

Several modifications to physical vapor deposition (PVD) models are proposed to address the deficiencies in current theoretical studies. Simple calculations show that the flow regime of PVD fabrications will most likely vary from a continuum flow to a rarefied flow in the vacuum chamber as the vapor cloud expands toward the substrate. The flow regime for an evaporated ideal gas is calculated and then an improved equation of state is constructed and analyzed that more accurately describes vaporized metals. The result, combined with experimental observations, suggests PVD fabrication is best represented by a multi-regime flow. Then, a CFD analysis is summarized that further validates the multi-regime analysis hypothesis. Finally, a methodology for constructing and implementing the results of a theoretical multi-regime PVD model is presented.
Two-Phase Heat Transfer Enhancement on Sintered Copper Microparticle Porous Structure Module Surface
Authors: Li Calvin H. , Li Ting , Kanney Brian
Published: July 2010

An experimental study of the pool boiling two-phase heat transfer on a sintered Cu microparticle porous structure module surface is conducted. Enhanced heat transfer capacity of this module surface has been reported, and the boiling characteristics have been investigated. The bubble dynamics and nucleate size distribution have been compared to the theoretical predictions, and the speculated mechanisms have been discussed.
Assessment of Tesla Turbine Performance for Small Scale Solar Rankine Combined Heat and Power Systems
Authors: Carey Van P.
Published: July 2010

For solar Rankine cycle combined heat and power systems for residential buildings and other small-scale applications (producing 1–10 kWe), a low manufacturing cost, robust and durable expander is especially attractive. The Tesla turbine design has these desired features. This paper summarizes a theoretical exploration of the performance of a Tesla Turbine as the expander in a small-scale Rankine cycle combine heat and power system. A one-dimensional idealized model of momentum transfer in the turbine rotor is presented which can be used to predict the efficiency of the turbine for typical conditions in these systems. The model adopts a non-dimensional formulation that identifies the dimensionless parameters that dictate performance features of the turbine. The model is shown to agree well with experimental performance data obtained in earlier tests of prototype Tesla turbine units. The model is used to explore the performance of this type of turbine for Rankine cycle applications using water as a working fluid. The model indicates that isentropic efficiencies above 0.70 can be achieved if the operating conditions are tailored in an optimal way. The scalability of the turbine design, and the impact of the theoretical model predictions on development of solar combined heat and power systems are also discussed.
Mode Coupling Behavior in End Milling
Authors: Huang C. Y. , Wang J.-J. Junz
Published: July 2010

Chatter is caused by two main mechanisms: the regenerative waviness and the mode coupling. Both of these two chatter mechanisms always exist simultaneously, but most studies only discuss the regenerative chatter behavior. The purpose of this paper is to investigate the mode coupling behavior in end milling process. A mechanical model considering both of the regenerative and mode coupling effects is then constructed to simulate the milling dynamics. It is shown that the stability of milling is dominated by the eigenvalues of the process matrix and the structure vibration trajectories are affected by the eigenvectors of the process matrix. The rotation direction of chatter vibration is an important feature to determine whether mode coupling chatter occurs or not. By analyzing vibration trajectories, this paper then shows that chatter vibration will rotate in the direction which periodically accumulates the vibration energy. Finally, some methods for adjusting the cutting conditions to avoid the mode coupling chatter are proposed.
Frost Thickness Variation on a Circular Tube Under Heat Pump Condition
Authors: Lee Yoon Suk , Yoon Shin Hyuk , Cho Keumnam , Hayase Gaku
Published: July 2010

The present study measured frost pattern on a circular tube to propose empirical correlation equations for the local and average frost thickness, frost density and frost mass. The key parameters were diameter of the circular tube (7mm, 20mm), cooling surface temperature of the circular tube, absolute humidity of air, air temperature, and air velocity. A 50% ethylene glycol aqueous solution was applied as a coolant. The effect of the air temperature was smaller parameters for the frost formation than the other parameters. The frost thicknesses at both front and rear of the tube were larger than those at the other parts, while they became higher with increasing the diameter of the circular tube. The local frost thicknesses at high air velocity were more uniform than those at low air velocity. The values predicted by the correlation under the freezer condition showed larger by the maximum of 30∼50% than the measured data under heat pump condition. The empirical correlations for the local and average frost thickness and frost mass were proposed. The empirical correlations for the local and average frost thickness, frost density and frost mass were proposed, and they agreed with the literatures within 10%.
Application of Thermal Hydraulic Code SOCRAT/V2 to Top Water Reflood Experiment PARAMETER-SF3
Authors: Vasiliev Alexander D.
Published: July 2010

The PARAMETER-SF3 test conditions simulated a severe LOCA (Loss of Coolant Accident) nuclear power plant sequence in which the overheated up to 1700–2300K core would be reflooded from the top and the bottom in occasion of ECCS (Emergency Core Cooling System) recovery. The test was successfully conducted at the NPO “LUTCH”, Podolsk, Russia, in October 31, 2008, and was the third of four experiments of series PARAMETER-SF. PARAMETER facility of NPO “LUTCH”, Podolsk, is designed for studies of the VVER fuel assemblies behavior under conditions simulating design basis, beyond design basis and severe accidents. The test bundle was made up of 19 fuel rod simulators with a length of approximately 3.12 m (heated rod simulators) and 2.92 m (unheated rod simulator). Heating was carried out electrically using 4-mm-diameter tantalum heating elements installed in the center of the rods and surrounded by annular UO2 pellets. The rod cladding was identical to that used in VVERs: Zr1%Nb, 9.13 mm outside diameter, 0.7 mm wall thickness. After the maximum cladding temperature of about 1900K was reached in the bundle during PARAMETER-SF3 test, the top flooding was initiated. The thermal hydraulic and SFD (Severe Fuel Damage) best estimate numerical complex SOCRAT/V2 was used for the calculation of PARAMETER-SF3 experiment. The counter-current flow limitation (CCFL) model was implemented to best estimate numerical code SOCRAT/V2 developed for modeling thermal hydraulics and severe accident phenomena in a reactor. Thermal hydraulics in PARAMETER-SF3 experiment played very important role and its adequate modeling is important for the thermal analysis. The results obtained by the complex SOCRAT/V2 were compared with experimental data concerning different aspects of thermal hydraulics behavior including the CCFL phenomenon during the reflood. The temperature experimental data were found to be in a good agreement with calculated results. It is indicative of the adequacy of modeling the complicated thermo-hydraulic behavior in the PARAMETER-SF3 test.