bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Simplified Experimental Model to Simulate an Air Conditioner
Authors: Rosario Luis , Rahman Muhammad M. , Porteiro Jose L. F. 
Published: November 2021

Abstract
A simplified model based on experimental data has been developed for applications in air-conditioning systems simulations. Cycle thermodynamic relationships, along with experimental data, were used to mathematically model the air-conditioning system. Characteristic parameters of the equipment were determined from the results of a limited number of test points. The following parameters were used: the clearance factor C, the piston displacement PD, the efficiency of the compressor ηcomp, the sensible heat factor SHF and the product of the overall heat transfer coefficient times area (UA) for the heat exchangers. Component performance simulation data was validated using experimental data from a 3-ton air conditioner. The model calculates the following parameters: coefficient of performance (COP), system capacity (qe), system heat rejection (qc), and compressor power (W) at any operating condition. The simulation model consists of work and energy balance relationships for the evaporator, condenser, expansion device, and compressor. The model predicted system heat rejection (qc) and system capacity (qe) within 10% of experimental data. The required compressor power (W) was predicted within 5% of uncertainty. However, the coefficient of performance (COP) had an uncertainty slightly higher than ±13% when compared to experimental data. The simulation model can be used as an effective tool for much faster equipment certification minimizing the required number of testing points.
The Effect of Roll Waves on the Hydrodynamics of Falling Films Observed in Vertical Column Absorbers
Authors: Miller William A. , Keyhani Majid 
Published: November 2021

Abstract
A thin falling film is well suited to simultaneous heat and mass transfer because of the small thermal resistance through the film and because of the large contact surface achievable at low flow rates. The film enters as a smooth laminar flow and quickly transitions into small-amplitude wavy flow. The waves grow in length and amplitude and are identified as roll waves. This flow regime is termed “wavy-laminar flow,” and modern heat and mass transfer equipment operate in this complicated transition regime. Research published in open literature has shown the mass flow rate in the roll waves to be about 10 to 20 times greater than that in the laminar substrate. As the film fully develops, the waves grow in mass and the film substrate thins because fluid is swept from the substrate by the secondary flows of the roll wave.
Many studies have been conducted to measure and correlate the film thickness of wavy-laminar flows. Literature data show that Nusselt’s theory for smooth laminar flow can over predict the film thickness by as much as 20% for certain wavy-laminar flow conditions. The hydrodynamics of falling films were therefore studied to measure the film thickness of a free-surface falling film and to better understand the parameters that affect the variations of the film thickness.
A flow loop was set up for measuring the thickness, wave amplitude, and frequency of a film during hydrodynamic flow. Decreasing the pipe diameter caused the amplitude of the wavy flow to diminish. Measurements monitored from stations along the falling film showed a thinning of film thickness. Fully developed flow required large starting lengths of about 0.5 m. The film thickness increases as the Reynolds number (Re) increases. Increasing the Kapitza number (Ka) causes a decrease in the film thickness. Regression analysis showed that the Re and Ka numbers described the data trends in wavy-laminar flow. Rather than correlating the Re number in discrete ranges of the Ka number as earlier researchers have done, this research made the Ka number an independent regression variable along with the Re number. The correlation explains 96% of the total variation in the data and predicts the experimental data within an absolute average deviation of ±4.0%. The correlation supports the calculation of a fully developed film thickness for wavy-laminar falling films.
Single Stage Heat Transformer Used to Recover Energy in an Oil Distillation Column
Authors: Rivera W. , Cerezo J. 
Published: November 2021

Abstract
This paper presents the theoretical analysis of the use of a single stage absorption heat transformer operating with the water-lithium bromide mixture coupled to an oil distillation column installed in a Mexican refinery.
The distillation column is used to produce mainly C5H12-1 and C5H12.2. Actually, the heat load in the condenser column is delivered to the atmosphere at 82°C while heat is supplied to the reboiler of the column at 115°C to distill the oil products.
In order to reduce the heat load supplied to the reboiler a single stage heat transformer may be coupled of the way that the heat delivered in the condenser may be used as heat input in the generator and evaporator of the heat transformer which increases the heat to a more useful level in the absorber to preheat the stream entering to the reboiler.
To do this, a mathematical model of a heat transformer was developed in FORTRAN and introduced to the software ASPEN PLUS. Both components coupled were modelled on steady state conditions.
The results showed that the coefficient of performance of the heat transformer which is directly related with the energy saving in the column is highly dependent of the condenser and absorber temperatures of the heat transformer.
At a condenser temperature of 22°C (cooling water temperature of 14°C and ΔT = 8°C) which can be obtained in winter time in that part of Mexico, up to 43% of the energy supplied to the reboiler of the distillation column may be saved by using the heat transformer, but in general at a condenser temperature of 30°C, which is a more representative temperature during a whole year, up to 30% of the energy may be saved.
Also, it was shown that the reboiler’s area may be reduce considerably if the distillation column was built since the beginning integrating a heat transformer, which may helps to reduce the extra capital costs caused by the use of the heat transformer.
Combined Space-Heating/Water-Heating System Performance
Authors: Baskin Evelyn , Spears John 
Published: November 2021

Abstract
With increasing fuel prices, various energy-saving techniques have been considered for residential appliances. Space heating accounts for the largest energy use in residential applications. One method proposed by manufacturers to keep operating cost low is to combine residential water-heating and space-heating functions into a single system. This paper presents the field test results of the performance of a combined water-heating/space-heating system under actual usage conditions. The system was installed in an 1187 ft2 (110 m2) home (Green Home) located in the Washington DC area. Data were collected for a one-year period. The water-heating performance was established by evaluating the hot water usage data during the test period. Water-heating/space-heating performance was established by using hot water data plus the amount of hot water circulated for space heating during the winter months. Analysis of the data indicated that the system produces hot water at an efficiency averaging 48% for water heating in the summer months and produces hot water at an efficiency ranging between 63.5–69.4% for combined water-heating/space-heating during the winter months. The relative humidity was maintained in the home at substantially lower level than that of the outside air, and the inside temperature was kept at the desired setting.
Design and Experimental Results of Small-Scale Rotary Engines
Authors: Fu Kelvin , Knobloch Aaron J. , Martinez Fabian C. , Walther David C. , Fernandez-Pello Carlos , Pisano Al P. , Liepmann Dorian , Miyaska Kenji , Maruta Kaoru 
Published: November 2021

Abstract
A research project is currently underway to develop small-scale internal combustion engines fueled by liquid hydrocarbons. The ultimate goal of the MEMS Rotary Internal Combustion Engine Project is to develop a liquid hydrocarbon fueled MEMS-size rotary internal combustion micro-engine capable of delivering power on the order of milli-watts. This research is part of a larger effort to develop a portable, autonomous power generation system with an order of magnitude improvement in energy density over alkaline or lithium-ion batteries. The rotary (Wankel-type) engine is well suited for the fabrication techniques developed in the integrated chip (IC) community and refined by the MicroElectroMechanical Systems (MEMS) field. Features of the rotary engine that lend itself to MEMS fabrication are its planar construction, high specific power, and self-valving operation.
The project aims at developing a “micro-rotary” engine with an epitrochoidal-shaped housing under 1 mm3 in size and with a rotor swept volume of 0.08 mm3. To investigate engine behavior and design issues, larger-scale “mini-rotary” engines have been fabricated from steel. Mini-rotary engine chambers are approximately 1000 mm3 to 1700 mm3 in size and their displacements range from 78 mm3 to 348 mm3.
A test bench for the mini-rotary engine has been developed and experiments have been conducted with gaseous-fueled mini-rotary engines to examine the effects of sealing, ignition, design, and thermal management on efficiency. Preliminary testing has shown net power output of up to 2.7 W at 9300 RPM. Testing has been performed using hydrogen-air mixtures and a range of spark and glow plug designs as the ignition source. Iterative design and testing of the mini-engine has lead to improved sealing designs. These particular designs are such that they can be incorporated into the fabrication of the micro-engine.
Design and fabrication of a first generation meso-scale rotary engine has been completed using a SiC molding process developed at Case Western Reserve University. The fabrication of the micro-rotary engine is being conducted in U.C. Berkeley’s Microfabrication Laboratory.
Testing of the mini-engine has lead to the conclusion that there are no fundamental phenomena that would prevent the operation of the micro-engine. However, heat loss and sealing issues are key for efficient operation of the micro-engine, and they must be taken into account in the design and fabrication of the micro-rotary engine. The mini-rotary engine design, testing, results and applications will be discussed in this paper.
Exergoeconomic Optimization of a Heat Exchanger With a Two-Phase Refrigerant
Authors: D’Accardia Massimo Dentice , Fichera Alberto , Sasso Maurizio , Vidiri Margherita 
Published: November 2021

Abstract
In this paper, the exergoeconomic theory is applied to a heat exchanger for optimization purposes. The investigation was referred to a tube-in-tube condenser with the single-phase fluid to be heated flowing in the inner annulus and the two-phase refrigerant flowing in the external annulus. First, the irreversibility due to heat transfer across the stream-to-stream temperature difference and to frictional pressure drops is calculated as a function of two design variables: the inner tube diameter and the saturation temperature of the refrigerant, on which the heat-exchange area directly depends. Then, a cost function is introduced, defined as the sum of two contributions: the amortization cost of the condenser under study and the operating cost of the conventional electric-driven heat pump in which this component will have to work. The latter contribution is directly related to the overall exergy destruction rate in the plant, whereas the amortization cost mainly depends on the heat-exchange area. So, design optimization of the device can be performed by minimising this cost function with respect to the selected design variables. The so-called structural approach (Coefficients of Structural Bond) is used in the optimization, in order to relate the local irreversibility in the condenser to the overall exergy destruction rate in the heat-pump plant. A numerical example is discussed, in which, for a commercial heat exchanger, the design improvements needed to obtain a cost-optimal configuration are investigated. The results show that significant improvements can be obtained with respect to devices based on conventional values of the design parameters.
The Exergy of Lift, and Aircraft Exergy Flow Diagrams
Authors: Paulus David M. , Gaggioli Richard A. 
Published: November 2021

Abstract
Aside from incidental, auxiliary loads, in level flight the principal load on the aircraft propulsion engine is the power required to provide the continuous lift. To construct an exergy flow diagram for an aircraft — for example, for the purpose of exergy costing — an expression is needed for the exergy delivered to (and by) the wings. That is, an expression is needed for the exergy of lift. In this paper an expression is developed for this quantity, applicable not only in level flight but in other modes of flight as well. Then, three exergy flow diagrams are presented for a light aircraft, operating under three conditions: climb, level economy cruise, and level maximum power. The expression for lift exergy and these exergy flow diagrams are relevant to the optimal design of aircraft subsystems [1].
One-Dimensional, Transient Model of Heat, Mass, and Charge Transfer in a Proton Exchange Membrane
Authors: Eaton Brandon , von Spakovsky Michael R. , Ellis Michael W. , Nelson Douglas J. , Olsommer Benoit , Siegel Nathan 
Published: November 2021

Abstract
A transient, one-dimensional, model of the membrane of a proton exchange membrane fuel cell is presented. The role of the membrane is to transport protons from the anode to cathode of the fuel cell while preventing the transport of other reactants. The membrane is modeled assuming mono-phase, multi-species flow. For water transport, the principle driving forces modeled are a convective force, an osmotic force (i.e. diffusion), and an electric force. The first of these results from a pressure gradient, the second from a concentration gradient, and the third from the migration of protons from anode to cathode and their effect (drag) on the dipole water molecules. Equations are developed for the conservation of protons and water, the conservation of thermal energy, and the variation of proton potential within the membrane.
The model is solved using a fully implicit finite difference approach. Results showing the effects of current density, pressure gradients, water and heat fluxes, and fuel cell start-up on water concentration, temperature, and proton potential across the membrane are presented.
Operating State Historical Data Analysis to Support Gas Turbine Malfunction Detection
Authors: Pinelli M. , Venturini M. 
Published: November 2021

Abstract
The paper describes a methodology to determine gas turbine operating state based on the analysis of normalized field data. This methodology consists in normalizing measured value with respect to that expected, calculated in the actual boundary conditions and working point. The normalization procedure, if applied on line, provides useful information to support the machine Health State determination.
In this paper, the methodology has been applied to field measurements taken on a 5 MW gas turbine running in a natural gas compression plant. The first results of field measurements analysis along a two year period are presented. Relations between compressor performance drops and the probable causes of malfunctioning have been identified. Some significant results are then presented.
Comparison Between Speco-Based and Functional Exergoeconomic Approaches
Authors: Lazzaretto Andrea , Tsatsaronis George 
Published: November 2021

Abstract
Various exergoeconomic approaches have been developed in the last 20 years. These approaches include the ones by Frangopoulos, Lazzaretto, Tsatsaronis, Valero, von Spakovsky and their co-workers. The paper discusses exergoeconomic approaches based on specific costs (SPECO), thermoeconomic functional analysis (TFA) and engineering functional analysis (EFA). Simple examples are used to demonstrate the differences among these approaches.
A Diagnosis Procedure for Energy Conversion Plants: Part I — Description of the Method
Authors: Stoppato Anna , Carraretto Cristian , Mirandola Alberto 
Published: November 2021

Abstract
In order to achieve the “best” use of energetic and economic resources, not only the design of a power plant has to be “optimized”, but also its operation and management according to users demand and boundary conditions. So, the availability of procedures and tools able to perform diagnosis activities is important in both locating the causes of malfunctions and evaluating their influence on the plant performances.
The Part I of this paper presents a diagnosis method, whose target is to evaluate the deviations of the plant performances from “reference values”, identify their causes and quantify their influence.
The method is based on the exergetic and the exergoeconomic analyses and supplies some indicators of performance related to energetic and economic aspects; the use of these indicators helps the analyst plan proper operation or maintenance actions.
Part II of the paper will discuss the results obtained by checking the actual operation of some power and cogenerative plants.
Proton Exchange Membrane (PEM) Fuel Cell System Model for Automotive Vehicle Simulation and Control
Authors: Boettner Daisie D. , Paganelli Gino , Guezennec Yann G. , Rizzoni Giorgio , Moran Michael J. 
Published: November 2021

Abstract
This paper describes a Proton Exchange Membrane (PEM) fuel cell system model for automotive applications that includes an air compressor, cooling system, and other auxiliaries. The fuel cell system model has been integrated into a vehicle performance simulator that determines fuel economy and allows consideration of control strategies. Significant fuel cell system efficiency improvements may be possible through control of the air compressor and other auxiliaries. Fuel cell system efficiency results are presented for two limiting air compressor cases: ideal control and no control. Extension of the present analysis to hybrid configurations consisting of a fuel cell system and battery is currently under study.
Product Design and Development of Automated Waste Removal System for the Handicapped
Authors: McGrath Thomas P. , Butler Daniel T. , Matthews Daniel C. , Latgis Jason , Zink Laurie E. , King Russell T. 
Published: November 2021

Abstract
This paper describes the product design and development process for an electrically operated residential waste removal system. The objective of the project is to provide an alternative method for elderly or handicapped persons to remove household trash, without the difficulties of lifting, tying, and disposing or the cost of complicated trash compacting systems. The ultimate goal of the system is to increase the quality of life for the physically handicapped. Automatically removing household trash from the home will increase the self-sufficiency of the handicapped, and decrease the chance of injury associated with everyday tasks.
A Smith Machine for Exercise in Micro-Gravity
Authors: House Audrey S. , Taylor Jenny L. , Lee Daina L. , Jones G. Marshall , Todd Beth A. , Lee Thomas B. D. , Wilson Kristin L. , Lancaster Bethany R. , Wear Richard 
Published: November 2021

Abstract
In a zero-gravity environment, astronauts exhibit Bone Mineral Density (BMD) loss in their spine and lower extremities with no net changes in the upper extremities [1]. Astronauts use their upper extremities for locomotion in flight by pushing off of the walls of the spacecraft, but since their lower extremities are not supporting their mass, as in gravitational loading, there is significant BMD loss in these areas.
The Influence of Experiment Conditions on Osteon Pushout Tests
Authors: Dong X. Neil , Guo X. Edward 
Published: November 2021

Abstract
Cement lines are boundaries between secondary osteons and the surrounding interstitial bone tissue in cortical bone as well as between trabecular packets in trabecular bone tissue. The interfacial properties of cement lines have been determined by performing an osteon pushout test [1]. It supported the hypothesis that the cement line is a weak interface.
In Vitro Comparison of a Translational Anterior Cervical Plate With a Constrained Anterior Cervical Plate
Authors: DiAngelo Denis J. , Liu Weiqiang , Olney Kristine M. , Foley Kevin T. 
Published: November 2021

Abstract
Cervical spondylosis is the most common degenerative disorder affecting the cervical spine and is often treated surgically to prevent further neurological deterioration. However, clinical experience has shown that anterior cervical plating does not prevent construct failure in multi-level cervical corpectomy (Vaccaro et al., 1998). We have previously shown that anterior cervical plating reverses the load transfer through multi-level strut-grafts and may promote pistoning of these grafts (DiAngelo et al., 2000). The design of the anterior cervical plate (ACP) may contribute to this phenomenon. The purpose of this study was to compare the graft loading mechanics of two different anterior cervical plating systems; one with a constrained plate-screw interface versus another with a semi-constrained, translational plate-screw interface.
An Experimental Model of Adult-Onset Slip Progression in Isthmic Spondylolisthesis
Authors: Patwardhan Avinash G. , Simonds James , Ghanayem Alexander J. , Voronov Leonard , Ali Arif , Hodges Scott D. , Paxinos Odysseas , Havey Robert M. , Phillips Frank , Gavin Thomas M. , Meade Kevin P. 
Published: November 2021

Abstract
Spondylolisthesis is defined as a slippage of a vertebral body on the one below. Isthmic spondylolisthesis, caused by stress fracture or a developmental anomaly at the pars interarticularis, is the most common type of lumbar spondylolisthesis with a 6% incidence in adults. Isthmic lumbar spondylolisthesis is a frequent cause of disabling low-back and leg pain. The goal of this study is to improve the quality of treatment of these patients.
Vertebral Bone Compression Fracture Analysis With and Without Synthetic Materials
Authors: Higgins Kathryn B. , Langrana Noshir A. , Harten Robert D. , Cuitino Alberto M. , Reiter Mitchell F. 
Published: November 2021

Abstract
The vertebral body is a mass of spongy bone contained in a dense cortical shell. The cancellous core is comprised of vertical and horizontal trabeculae. The shape and orientation of these trabeculae is referred to as the microarchitecture of the cancellous bone. A great deal of information on the function of vertebral bodies can be determined by analyzing the biomechanics and morphology of cancellous bone. [1] A model for analysis must accurately represent the trabecular pattern of the vertebral body. That model can then be used to predict mechanical properties of bone under various conditions.
Three-Dimensional Dynamic Modeling of the Human Knee to Include Tibio-Femoral and Patello-Femoral Joints
Authors: Caruntu Dumitru , Hefzy Mohamed Samir 
Published: November 2021

Abstract
Most of the anatomical mathematical models that have been developed to study the human knee are either for the tibio-femoral joint (TFJ) or patello-femoral joint (PFJ). Also, most of these models are static or quasistatic, and therefore do not predict the effects of dynamic inertial loads, which occur in many locomotor activities. The only dynamic anatomical model that includes both joints is a two-dimensional model by Tumer and Engin [1]. The model by Abdel-Rahman and Hefzy [2] is the only three dimensional dynamic model for the knee joint available in the literature; yet, it includes only the TFJ and allows only for rigid contact.