bluuebunny/crossref_metadata_2025_split huggingface dataset:
Energy and Environmental Impact of Groundwater Heat Pumps in Urban Areas
Authors: Verda Vittorio , Sciacovelli Adriano , Lo Russo Stefano , Taddia Glenda 
Published: October 2013

Heat pumps are expected to play a major role in future energy scenarios. Proliferation of these systems in urban areas may cause issues related to environmental impact on water basins and interactions between installations. Both issues are associated with the thermal plume produced by the heat pump during operation and are particularly evident in the case of groundwater flow, because of the advective term of heat transfer.
In this paper, the impact of heat pump installations is calculated through a thermo-fluid dynamic model of the subsurface which considers fluid flow in the saturated unit and heat transfer both in the saturated and unsaturated units. This model is coupled with the thermal request of the user and the heat pump performances through appropriate boundary conditions imposed at the wells. Various scenarios corresponding to different annual heating/cooling request, groundwater velocity, groundwater temperature variation are considered.
Thermoeconomic Diagnosis Applied to the Transient Operation of a Microturbine
Authors: Verda Vittorio , Baccino Giorgia 
Published: October 2013

The use of thermoeconomic analysis for the diagnosis of malfunctions causing efficiency reductions in energy systems has been widely discussed in the literature. The main objectives of thermoeconomic procedures are to discover malfunctions, locate the components where they have taken place, help one to identify the possible causes and quantify the impact in terms of additional energy resource consumption.
In this paper, thermoeconomic diagnosis is applied to discover possible malfunctions of a microturbine. The procedure consists in the use of compact productive models of the components, which relate their exergetic products to their resources. Two different types of productive models are used: linear model and non linear model. The latter is built using neural networks.
The main interest in the proposed application is that transient operation of the system is investigated. Results show that diagnosis can be performed both in steady state and transient conditions. The neural network model allows one to detect the anomaly with better accuracy than the linear model.
A Semi-Analytical Solution Method for the Adhesive Contact Between a Rigid Punch and Multi-Layered Functionally Graded Material
Authors: Chidlow Stewart , Teodorescu Mircea 
Published: October 2013

The current paper proposes a semi-analytical solution method which predicts both the sub-surface stress fields and pressures that result from adhesive contact between a multi-layered functionally graded material (FGM) and a rigid punch. The FGM is deemed to consist of a homogeneously elastic coating and substrate joined together by a transition layer whose shear modulus depends on the depth coordinate in some predetermined way. It is further assumed that the FGM is in a state of plane strain so that we may perform a two-dimensional analysis.
We present analytical solutions for the horizontal and vertical displacements within the solid which hold when the applied surface pressure is known and then discuss how we may use these solutions to solve the contact problem. A selection of numerical results are then presented using this model and it is found that the algorithm proposed in this work is both accurate and computationally cheap to use.
Experimental Testing of Annular Target Surrogates for the Production of Molybdenum-99
Authors: Makarewicz Philip F. , Govindarajan Srisharan Garg , Solbrekken Gary L. 
Published: October 2013

Technetium-99m (Tc-99m) is a diagnostic radiopharmaceutical that is currently used about 100,000 times daily for diagnostic imaging procedures globally [1]. The parent isotope for Tc-99m is molybdenum-99 (Mo-99), most commonly obtained through the irradiation of high enriched uranium (HEU). In accordance with the Department of Energy’s Global Threat Reduction Initiative (GTRI), an effort is underway to develop a process to produce Mo-99 using low enriched uranium (LEU). One method utilizes LEU cast in the form of a metal foil as opposed to current powder based dispersion designs for HEU. New high-volume production LEU target concepts need to be analyzed to assure safe, reliable operation during all stages of production as use of a foil requires a significant modification to the current target design.
Analytic and numeric models have been built to simulate the thermal-mechanical behavior of LEU-foil based targets under irradiation conditions. Experimental testing is being used to validate the models. Heating conditions are controlled by heater placement and cooling water circulation to place the target interfaces into controlled states of compression and tension. Thermocouples are used to measure the temperature at key locations so that the thermal contact resistance can be evaluated and compared with the predictions.
A Fundamental View of the Flow Boiling Heat Transfer Characteristics of Nano-Refrigerants
Authors: Cremaschi Lorenzo 
Published: October 2013

Driven by higher energy efficiency targets and industrial needs of process intensification and miniaturization, nanofluids have been proposed in energy conversion, power generation, chemical, electronic cooling, biological, and environmental systems. In space conditioning and in cooling systems for high power density electronics, vapor compression cycles provide cooling. The working fluid is a refrigerant and oil mixture. A small amount of lubricating oil is needed to lubricate and to seal the sliding parts of the compressors. In heat exchangers the oil in excess penalizes the heat transfer and increases the flow losses: both effects are highly undesired but yet unavoidable.
This paper studies the heat transfer characteristics of nanorefrigerants, a new class of nanofluids defined as refrigerant and lubricant mixtures in which nano-size particles are dispersed in the high-viscosity liquid phase. The heat transfer coefficient is strongly governed by the viscous film excess layer that resides at the wall surface. In the state-of-the-art knowledge, while nanoparticles in the refrigerant and lubricant mixtures were recently experimentally studied and yielded convective in-tube flow boiling heat transfer enhancements by as much as 101%, the interactions of nanoparticles with the mixture still pose several open questions. The model developed in this work suggested that the nanoparticles in this excess layer generate a micro-convective mass flux transverse to the flow direction that augments the thermal energy transport within the oil film in addition to the macroscopic heat conduction and fluid convection effects. The nanoparticles motion in the shearing-induced and non-uniform shear rate field is added to the motion of the nanoparticles due to their own Brownian diffusion. The augmentation of the liquid phase thermal conductivity was predicted by the developed model but alone it did not fully explain the intensification on the two-phase flow boiling heat transfer coefficient reported in previous work in the literature. Thus, additional nano- and micro-scale heat transfer intensification mechanisms were proposed.
Optimization of Large Wind Farms Using a Genetic Algorithm
Authors: Mittal Anshul , Taylor Lafayette K. 
Published: October 2013

Optimizing the placement of the wind turbines in a wind farm to achieve optimal performance is an active area of research, with numerous research studies being published every year. Typically, the area available for the wind farm is divided into cells (a cell may/may not contain a wind turbine) and an optimization algorithm is used. In this study, the effect of the cell size on the optimal layout is being investigated by reducing it from five rotor diameter (previous studies) to 1/40 rotor diameter (present study).
A code is developed for optimizing the placement of wind turbines in large wind farms. The objective is to minimize the cost per unit power produced from the wind farm. A genetic algorithm is employed for the optimization. The velocity deficits in the wake of the wind turbines are estimated using a simple wake model. The code is verified using the results from the previous studies. Results are obtained for three different wind regimes: (1) Constant wind speed and fixed wind direction, (2) constant wind speed and variable wind direction, and (3) variable wind speed and variable wind direction. Cost per unit power is reduced by 11.7% for Case 1, 11.8% for Case 2, and 15.9% for Case 3 for results obtained in this study. The advantages/benefits of a refined grid spacing of 1/40 rotor diameter (1 m) are evident and are discussed.
To get an understanding of the sensitivity of the power produced to the wake model, optimized layout is obtained for the Case 1 using a different wake model.
On Demand Thermal Protection (ODTP): A New Approach for Designing Garments Exposed to Flash Flame Incidents
Authors: Mendoza Eduardo , Cooper Jean-pierre , Evangelista John W. , Auerbach Margaret , Arnas Özer 
Published: October 2013

Soldiers, first responders and other high risk occupations such as power line technicians are routinely exposed to dangerous situations where severe burn injuries are possible. Standard flame resistant (FR) fabrics provide minimal burn protection when exposed to a flash flame incident. As a result, improvement in thermal protection is desperately needed and remains an ongoing subject of research and development. A simplified one dimensional physical model composed of a muscle layer, skin/fat layer, air gap(s) and fabric layer(s) is used to model heat transfer entering the body covered by a garment that is exposed to a flash flame. Heat transfer within the skin and muscle layers is modeled by combined conduction, metabolic heat generation and blood perfusion by a recently developed modification to the heat equation termed the bio-heat equation. Boundary conditions include a fixed temperature (core body temperature) at the inside of the muscle layer and combined convection and radiation from the flame on the outside of the fabric. The heat equation is solved by discretizing the domain in one dimension and using a finite volume approach to derive the finite difference equations. This model is an initial step to be used to provide an assessment of common FR garments with respect to both comfort in ambient conditions and protection during a flash flame. It also provides for parametric analysis to determine ideal thermo-physical properties, fabric thicknesses and layering for better protection during flash flame incidents. Estimates for time to burn injury from the numerical model is presented with experimental results using live mannequin flame tests (ASTMF-1930), standard vertical flame tests (ISO-17492) and a non-standard flame test with combined convection and radiation heat fluxes up to 85 kW/m2.
The main effort of this study revolves around an initial working design for a dynamic garment termed On Demand Thermal Protection (ODTP). The primary focus of the design is the development of a thermistor circuit embedded in a protective garment to act as an electric sensor for rapidly deploying the necessary thermal protection that is needed as predicted by the numerical model instantaneously in the event of a flash flame incident. An initial prototype is being developed with a focus on designing the thermistor circuit to mechanically actuate protective components in a flash-flame environment. Concepts include rapidly releasing a pressurized flame retardant fluid through vinyl tubing sewn into a garment and deploying a protective barrier around the face and neck when the thermistor circuit detects a sudden change in heat transfer. A summary of the prototype along with experimental testing to date compared to the theoretical predictions from the model described above is presented.
A Uniform Standard for the Teaching of Energy Perspectives in Statistics and Dynamics
Authors: Kobus C. J. , Chang Y. P. 
Published: October 2013

It has become increasingly apparent in our combined years of teaching engineering subjects that there is a discontinuity between how related subjects are taught. By that, we mean that fundamental principles of mass, energy and momentum are indifferent to the application, yet they are introduced and utilized very differently in various engineering courses, specifically those in the general area of solid mechanics versus those in the fluid and thermal sciences. One example of this disparity is the conservation of energy principle, one of the two most fundamental of principles for which all things appear subject to without limitation. Also known as the 1st Law of Thermodynamics, the statement simply says “energy cannot be created nor destroyed.” This implies that, within these broad but absolute limits, energy can be converted from one form to another or transported from one place to another, or both, but that the total energy remains a constant.
This 1st Law of Thermodynamics is taught earlier in the curriculum from its namesake, thermodynamics. In fact, most introductory statics and dynamics courses do teach some form of the conservation of energy, but usually call it “energy methods.” The plural form “energy methods” indicates that there is more than one, which can be readily observed in most statics and dynamics textbooks. Unfortunately, these methods are only special-cases of the conservation of energy principle. At no time, however, in any statics and dynamics textbook that we have seen, is the full conservation of energy principle utilized, which is unfortunate for reasons of consistency and continuity in the curriculum.
It is the intent of this paper to show, through an example, that the same basic form of the conservation of energy can and should be utilized throughout the curriculum, starting with basic statics and dynamics and progressing into thermodynamics and the rest of the curriculum. This would indeed help student comprehension and retention of this very important principle in implication and application.
Investigation of Riding Position Effects on Time-Trial Bicycle Drag Coefficient at Different Yaw Angles
Authors: Doval Peter N. , Avdeev Ilya V. 
Published: October 2013

Time-trial bicycle racing is highly influenced by aerodynamics, perhaps more so than any other form of bicycle racing. Companies competing in this class of racing spend millions of dollars trying to optimize the geometry of the bicycles and the gear each rider wears in order to reduce aerodynamic drag. The idea behind this project was to investigate other ways to optimize the aerodynamic efficiency of the rider, considering that the rider contributes the majority of the drag force of the bicycle-rider system. A large contributor to drag is the frontal area of the object of interest (a silhouette of the object in the fluid flow direction). This illustrates how much the rider’s body contributes to overall drag. If small riding adjustments could be made to the rider’s body during riding, drag may be significantly reduced. This idea and the fact that the direction of wind impacting the rider can vary influenced the concept of this project.
It was hypothesized that adjusting the time-trial handlebars on the bicycle to place one of the rider’s hands further aft than the other would influence the upper body to rotate slightly. This could then reduce the frontal area of the rider in the wind direction, therefore reducing the aerodynamic drag. To simulate this situation, a non-contact 3-D digitizer was used to scan a rider aboard a bicycle in a normal riding position and in the above-mentioned, asymmetric position. This 3-D scan was then imported into the computational fluid dynamics (CFD) program Star-CCM+ and several simulations were run. Each of the two riding positions was simulated at differing yaw angles, ranging from −45° to 45°. The initial simulations seem to prove the theory as the asymmetrical riding position experiences decreased drag at significant yaw angles while the normal riding position does not. These results are encouraging and it is desired to continue refinement of the scanning and simulation methods as well as to validate these findings in a wind tunnel.
Beta Testing a Web-Based Writing Coach
Authors: Todd Beth A. , Niiler Luke , Brown Marcus , Bahri Prateek , Tamondong Virginia , Beams David M. , Barth Joan , Warren Garry , Swinney Kenneth R. , Cordes David W. 
Published: October 2013

“The Coach” is a web-based tool developed to guide students through the technical writing process. It provides instruction about form as well as critique of different aspects of the students’ writing. It goes beyond the Microsoft word spell check and grammar check. It gives feedback about writing complexity and appropriateness for different word choices in a technical document. It also gives background about the appropriate contents for technical writing in addition to example documents. The latter is extremely important for the novice writer who may not have much experience in working with technical reports.
The initial document type in “The Coach” is a lab report. If the lab report can be developed into the web-based tool, other forms will be more easily implemented. In addition to developing the website, the development team is preparing a document and a video for a professor to use to instruct students on the use of “The Coach.”
The instructional materials and “The Coach” were beta tested with a freshman engineering class. A baseline writing sample was collected before the introduction of “The Coach.” Students in some sections were instructed in use of “The Coach,” and other sections were controls. Additional beta testing is ongoing.
Development and Optimization of a Small Scale Pellet Burner
Authors: Teixeira José Carlos , Ferreira Rui , Seabra Eurico A. , Ferreira Manuel Eduardo 
Published: October 2013

Environmental concerns and the drive to reduce the dependence on petroleum brought the use of renewable energies to the forefront. Biomass appears as a very interesting alternative for direct conversion into heat. In this context, densified forms of biomass such as pellets are of great relevance because of their easy of use, high efficiency and low emissions.
The practical interest in pellet combustion has been driven by the domestic heating sector, which favors the characteristics that are intrinsic of this fuel, despite its relatively higher price. However, the growing costs of fossil fuels have extended the interest of pellet fuels into industrial applications, including co-firing in power stations.
A fast growing market includes the retrofitting of existing fuel boilers and furnaces with alternative burners that can be fitted into existing combustion systems. Such an approach has proved very attractive due to the low installation cost and the growing existence of fuels produced in the vicinity of the end user. This involves in most cases a custom built application which requires a high level of flexibility to variable operating conditions.
This work reports on the development of a 120 kW pellet burner. A prototype of the burner was built that enables the independent control of the air supply into various regions of the combustion chamber and an accurate supply of fuel. The burner was fitted into a testing furnace of cylindrical shape oriented horizontally. Its diameter is 0.5 m and is constructed in a modular fashion with a total length of 2.2 m. All the facility is fully instrumented and includes: temperature data in various locations inside the chamber, flue gases emissions (CO, CO2, NOx) measurements and flow rates.
The objective of the test and development is to optimize the combustion over the thermal load range of the facility. The excess air, fuel supply (primary and secondary) and the shape of the furnace grate enable the optimization of the burner with CO emissions of approximately 50 ppm, well below the acceptable limits.
Performance and Economic Analysis of Biomass/Coal Co-Gasification IGCC Systems With Supercritical Steam Bottom Cycle: Part 1 — Post-Combustion Carbon Capture
Authors: Wang Ting , Long Henry A. 
Published: October 2013

In recent years, Integrated Gasification Combined Cycle (IGCC) technology has been gaining steady popularity for use in clean coal power operations with Carbon Capture and Sequestration (CCS). This study focuses on investigating two approaches to improve efficiency and further reduce the greenhouse gas (GHG) emissions. First, replace the traditional subcritical Rankine steam cycle portion of the overall plant with a supercritical steam cycle. Second, add different amounts of biomass as feedstock to reduce emissions. Part 1 focuses on investigating post-combustion CCS and Part 2 on analyzing pre-combustion CCS, using both sour-shift and sweet-shift processes. Employing biomass as a feedstock has the advantage of being carbon neutral or even carbon negative if CCS is implemented. However, due to limited feedstock supply, such plants are usually small (2–50MW), which results in lower efficiency and higher capital and production costs. Considering these challenges, it is more economically attractive and less technically challenging to co-combust or co-gasify biomass wastes with coal.
Using the commercial software, Thermoflow®, this study analyzes the baseline plants around 235MW and 267 MW for the subcritical and supercritical designs, respectively. The results clearly show that utilizing a certain type of biomass with low-grade coals up to 50% (wt.) can, in most cases, not only improve the efficiency and reduce overall emissions, but may be economically advantageous, as well. The CO2 emissions decrease by about 7,000 tons/MW-year, making both plants carbon-negative with only 10% biomass in the feedstock. In addition, implementing a supercritical steam cycle raises the efficiency (1.6 percentage points) and lowers the capital costs ($300/kW), regardless of plant layout. Implementing post-combustion CCS consistently causes a drop in efficiency (at least 7–8 points) from the baseline, and increases the costs by $3,000-$4,000/kW and $0.06-$0.07/kW-hr. The SOx emissions also decrease by about 190 tons/year (7.6 × 10−6 tons/MW-year), while the NOx emissions are all but eliminated through post-combustion CCS. Finally, the CCS cost is around $65-$72 per ton of CO2.
Reinventing MEMS Through Genetic Programming
Authors: Ghoshal Samik , Clark Jason 
Published: October 2013

As the functional requirements of MEMS devices become more complex, advanced optimization techniques become more necessary in determining acceptable parameters, or even creating new components to satisfy a desired output. These challenges are being met through the use of genetic programming (GP), a brand of optimization that determines parameters through its “artificial intelligence” selecting and choosing the best output.
The applications of genetic programming to MEMS have been mostly limited to the task of optimizing parameters and components for existing devices. In addition to these applications, GP can also be utilized to create original MEMS devices. Existing MEMS devices can also be reinvented to match the shape and structure of existing devices based solely on the device’s performance characteristics. This paper will discuss how the electro-thermal actuator and the chevron actuator were successfully reinvented through this process.