bluuebunny/crossref_metadata_2025_split huggingface dataset:
Design and Analysis of a High Temperature Particulate Hoist for Proposed Particle Heating Concentrator Solar Power Systems
Authors: Repole Kenzo K. D. , Jeter Sheldon M. 
Published: November 2016

The central receiver power tower (CRPT) with a particle heating receiver (PHR) is a form of concentrating solar power (CSP) system with strong potential to achieve high efficiency at low cost and to readily incorporate cost-effective thermal energy storage (TES). In such a system, particulates are released into the PHR, and are heated to high temperature by concentrated solar radiation from the associated heliostat field. After being heated, the particles will then typically flow into the hot bin of the TES. Particulates accumulated in the hot bin can flow through a heat exchanger to energize a power generation system or be held in the hot TES storage bin for later use such as meeting a late afternoon peak demand or even overnight generation. Particles leaving the heat exchanger are held in the low temperature bin of the TES.
A critical component in such a PHR system is the particle lift system, which must transport the particulate from the lower temperature TES bin back to the PHR. In our baseline 60 MW-thermal (MW-th) design, the particulate must be lifted around 70 m at the rate of 128 kg/s. For the eventual commercial scale system of a 460 MW-th design the particulate must be lifted around 138 m at the rate of 978 kg/s. The obvious demands on this subsystem require the selection and specification of a highly efficient, economical, and reliable lift design.
After an apparently exhaustive search of feasible alternatives, the skip hoist was selected as the most suitable general design concept. While other designs have not been dismissed, our currently preferred somewhat more specific preliminary design employs a Kimberly Skip (KS) in a two-skip counterbalanced configuration. This design appears to be feasible to fabricate and integrate with existing technology at an acceptably low cost per MW-th and to promise high overall energy use efficiency, long service life, and low maintenance cost. A cost and performance model has been developed to allow optimization of our design and the results of that study are also presented. Our developed design meets the relevant criteria to promote cost effective CSP electricity production.
Testing and Preliminary Modelling of a 2.5 kW Micro-CHP SOFC Unit
Authors: Mastropasqua Luca , Campanari Stefano , Valenti Gianluca , Guariniello Anna , Modena Stefano , Ghigliazza Francesco 
Published: November 2016

The experimental activities, carried out at the Laboratory of Micro-Cogeneration (LMC) of the Department of Energy at Politecnico di Milano are hereby outlined in relation to the testing of four 2.5 kWel AC SOFC-based micro-CHP units developed by SOLIDpower S.p.a.
The novelty of the work consists in carrying out a complete thermodynamic and environmental performance characterisation of the studied commercial system in a third-party laboratory.
The main objectives of the experimental campaign have been the investigation and assessment of the electric and heat recovery performances in different cogeneration thermal power demand loads.
The generator has been tested in five different thermal loads, whilst operated at full electric load, in order to simulate the coupling with thermal appliances of diverse nature. The cogeneration water inlet temperature has been varied from 20°C (as in more complex cogeneration systems which may envisage a thermal storage and additional pre-heating section) to 50°C (as for district heating purposes or heating of sanitary water).
Each measurement has been acquired with a redundant approach for statistical purposes aiming to the reduction of uncertainty and to guarantee procedure robustness.
Moreover, the design point experimental characterisation has been supported by an overall process calibration and simulation performed by means of an in-house software (GS), developed at the Department of Energy. Each component has been modelled using a 0D approach, such that the required mass and energy balances of the plant can be compared with those obtained from the experimental activity.
In conclusion, the overall performances have met the expectations, being characterised by a net electric efficiency of approximately 39% and a total efficiency which may overcome 95%.
Simulation of Model Predictive Control for a Fuel Cell/Gas Turbine Power System Based on Experimental Data and the Recursive Identification Method
Authors: Restrepo Bernardo , Banta Larry E. , Tucker David 
Published: November 2016

A Model Predictive Control (MPC) strategy has been suggested and simulated with the empirical dynamic data collected on the Hybrid Performance (HyPer) project facility installed at the National Energy Technology Laboratory (NETL), U.S. Department of Energy, in Morgantown, WV. The HyPer facility is able to simulate gasifier/fuel cell power systems and uses hardware-based simulation approach that couples a modified recuperated gas turbine cycle with hardware driven by a solid oxide fuel cell model. Dynamic data was collected by operating the HyPer facility continuously during five days. Bypass valves along with electric load of the system were manipulated and variables such as mass flow, turbine speed, temperature, pressure, among others were recorded for analysis. This work was developed by focusing on a multivariable recursive system identification structure fitting measured transient data. The results showed that real-time or online data is a viable means to provide a dynamic model for controller design.
The excursion dynamic data collected between the setup changes of the experiments was processed off-line to determine the feasibility of applying an adaptive Model Predictive Control strategy. One of the strengths of MPC is that it can allow the designer to impose strict limits on inputs and outputs in order to keep the system within known safe bounds. Two identification structures, ARX and a State-Space model, were used to fit the measured data to dynamic models of the HyPer facility. The State-Space identification was very accurate with a second order model. Visual inspection of the tracking accuracy shows that the ARX approach was approximately as accurate as the State-Space structure in its ability to reproduce measured data. However, by comparing the Loss Function and the FPE parameters, the State-Space approach gives better results.
The MPC proved to be a good strategy to control the HyPer facility. The airflow valves and the electric load were used to control the turbine speed and the cathode airflow. For the ARX/State Space models, the MPC was very robust in tracking set-point variations. The anticipation feature of the MPC was revealed to be a good tool to compensate time delays in the output variables of the facility or to anticipate eventual set-point moves in order to achieve the objectives very quickly. The MPC also displayed good disturbance rejection on the output variables when the fuel flow was set to simulate FC heat effluent disturbances. Different off-design scenarios of operation have been tested to confirm the estimated implementation behavior of the plant-controller dynamics.
Design, Energy Modeling and Performance of an Integrated Industrial Size Biogas SOFC System in a Wastewater Treatment Plant
Authors: Gandiglio Marta , Saberi Mehr Ali , Lanzini Andrea , Santarelli Massimo 
Published: November 2016

DEMOSOFC [1] is a Fuel Cell & Hydrogen Joint Undertaking (FCH-JU) funded project which foresees the installation of the largest biogas fed Solid Oxide Fuel Cell (SOFC) in Europe. The SOFC will be the sole combined heat & power (CHP) generator within a medium size wastewater treatment plant (WWTP) located in Torino (IT). Three SOFC modules, each rated 58 kWe, will supply around 30% of the internal electrical loads and a variable share of the thermal load depending on the season. The key objective of the project is to demonstrate the industrial readiness of SOFC systems, which are able to guarantee better performance both in terms of electrical efficiency and emission of pollutants with respect to conventional internal combustion engines.
SOFC systems have a high potential for integration with local renewable fuels as biogas and/or bio-syngas from waste sources. Looking at the biogas potential in EU, the most common plant size lies in the sub-MW scale.
This work aims to describe the DEMOSOFC concept, the approach followed for the design of the integrated system. Energy performance, environmental benefits, underlining advantages and barriers of this integration are presented and discussed.
Evacuation Systems for Steam Surface Condensers: Vacuum Pumps or Steam Jet Air Ejectors?
Authors: Nadig Ranga 
Published: November 2016

In a steam power plant, steam from the steam turbine is condensed in a water cooled or air cooled condenser that operates under vacuum. The condensing capacity of the condenser is impaired by the presence of air. Air leaks into the condenser from flanged connections, turbine seals, valves and other equipment connected to the condenser. The air tends to collect in the condenser and impact its condensing capability. This trapped air has to be continuously evacuated to preserve the condensing capacity of the condenser.
The air can be evacuated from the condenser using the steam jet air ejector system or the vacuum pump system. The vacuum pump is driven by an electrical motor. The steam jet air ejector is driven by motive steam. In certain low suction pressure applications, a hybrid system consisting of a steam jet air ejector and vacuum pump or a three stage ejector system is used for evacuating the air from the condenser.
The evacuation packages perform two distinct services namely hogging and holding. During startup, or hogging operation, the evacuation system removes air from the steam space of the condenser and steam turbine. The pressure in the steam space is reduced from atmospheric pressure to typically 10.0” HgA or a pressure specified by the steam turbine supplier in about 30 minutes. During normal or “holding operation” with the steam turbine in service, the evacuation system removes a specified amount of air from the condenser.
The suitability of vacuum pump or steam jet air ejector systems for a given application depends on the availability of motive steam during startup, the costs associated with the usage of steam or electricity and the preferences of the end user. Each system has its advantages and disadvantages. In each case, there are numerous design details that must be addressed to ensure that the selected system meets the evacuation needs for the condenser.
This paper examines the various configurations of evacuation systems and discusses their suitability for the wide ranging operating scenarios in the condenser. A broad background on the design and operation of the evacuation system is included to assist the end user in making the proper selection of the evacuation system.
The Science Behind Eddy Current and Remote Field Testing: For Condenser and Heat Exchanger Tubing
Authors: Van Name Christopher , Fischer Gary , Kocher James 
Published: November 2016

With the increasing demand on the world’s power grids, now more then ever it is important to keep power plant condensers, feedwater heaters and balance of plant heat exchangers running at peak efficiency. While it is well known that keeping these units clean is important for maximizing power output, so too is monitoring each unit’s tube integrity and taking corrective action to prevent tube failure. The best way to monitor a unit’s tube integrity, detect patterns of tube wear and damage, and determine the specific wear and damage to a particular tube is through Non-Destructive Testing. Depending on the tube material, the best Non-Destructive Testing method to employ would be either Eddy Current Testing, Remote Field Testing or other variations of these electromagnetic techniques.
This paper will discuss the science behind Eddy Current and Remote Field Testing, how they differ and which one to select depending on the situation. It will look at the construction of the probes and how they work. It will explain the difference between use of a single frequency or multiple frequencies and the advantages of multi-frequency testing. The paper will also identify the necessary procedure for a successful Non-Destructive Test, including the types of tubes that can be tested and tube preparation.
An Integrated Design Approach of Local Control System of a Linear Drive Single Facet Heliostat
Authors: Nageb M. M. , El-Samahy A. A. , Rady M. A. , Amin A. M. A. , Abd El-Hamid R. H. , Olasolo David 
Published: November 2016

In a central receiver solar power plant, heliostats are arranged with respect to the central receiver so as to reflect the rays from the sun onto the power tower with high precision by tracking the sun in both the azimuth and elevation directions. The master control system of a solar power plant consists of different levels. The first level is local control; it takes care of the positioning of the heliostats when the aiming point and the time are given to the system, and informs upper level about the status of the heliostats field. The second logic level makes some important dispatch calculations of heliostats field. The most popular linear two-axis local driving system of heliostat consists of two linear driving actuators, the driving mechanism with rotary joints, and the controller. Traditional methods for heliostat design are often based on a sequential approach in which the mechanical structure is designed first and then the control system is advised. In order to reach the optimal design of heliostats, an integrated design approach that concurrently considers the interactions between the mechanical and control subsystems is necessary. In this article, an integrated design methodology of heliostat drive system is presented.
The methodology is based on modeling and simulation. The dynamic models that describe the behavior of the mechanical and control components are presented. These models involve mechanical and control design variables such as the motor parameters, power screw (including back lash), heliostat mass, load forces, and wind forces. Matlab, Solidwork, and Simulink are chosen to apply PID tracking control to heliostats, due to the ability to arbitrarily model complex mechanical systems, directly import properly constructed, third-party 3D CAD models, simulate integrated control, handle a variety of robotics nomenclature, and other features. The present methodology is employed for integrated design of a single facet small size heliostat with mirror area of 3 m2.The methods described in this article also show a way to rapidly simulate novel and complex heliostat geometries. Analysis of the heliostat drive system performance and dynamic characteristics according to mechanical and control design variables is conducted for the purpose of control system design and performance optimization. The drive system performance is evaluated in terms of positioning tracking errors, system response, and control system behavior. It is shown that the mechanical characteristics of the ball power screw actuator such as ball-screw diameter, lead, overall flexibility, stiffness, backlash, and inertia significantly influence the performance of drive system.
Retracted: “Benchmark Thermodynamic Modelling Comparison of a Novel Modular Air-Cooled Condenser With Current Dry-Cooling Methodologies” [ASME 2016 Power Conference collocated with the ASME 2016 10th International Conference on Energy Sustainability and the ASME 2016 14th International Conference on Fuel Cell Science, Engineering and Technology, ASME 2016 Power Conference, Charlotte, North Carolina, USA, June 26–30, 2016, Conference Sponsors: Power Division, Advanced Energy Systems Division, Solar Energy Division, Nuclear Engineering Division, ISBN: 978-0-7918-5021-3. Paper No. POWER2016-59589, pp. V001T04A010; 9 pages; doi:10.1115/POWER2016-59589]
Authors: ASME  
Published: November 2016

This paper was withdrawn. ASME does not hold the copyright. December 21, 2018.
Copyright © 2018 by ASME
Mechanical Stress Optimisation in a Directly Illuminated Supercritical Carbon Dioxide Solar Receiver
Authors: Gardner Wilson , Kim Jin-Soo , McNaughton Robbie , Stein Wes , Potter Daniel 
Published: November 2016

CSIRO is constructing a solar thermal driven high temperature supercritical carbon dioxide (sCO2) Brayton cycle test facility, which includes an absorber tube based solar receiver, at the CSIRO National Solar Energy Centre in Newcastle, Australia. The sCO2 facility is capable of producing high temperature CO2 at 700° Celsius.
In this paper the mechanical challenges of designing a sCO2 solar receiver are presented. The design is an optimization of the impact of having a high thermal gradient through the absorber tube wall as a result of high heat transfer and the effect of containing sCO2 under high pressure inside the absorber tube. The first drives the design toward needing a thin tube wall to reduce the thermal gradient stress, whereas the high pressure drives the absorber tube toward needing a thick wall. It is worth noting that the thermal stress being considered here are those within the tube wall thickness only and not about the effects of thermal expansion along the length.
The contradictory nature of these two drivers resulted in an iterative approach to choosing the receiver’s optimal absorber tube size with nine options investigated and compared for optimal mutual design conditions for pipe wall stresses cause by internal pressure and thermal gradient. This led to choosing the smallest available pipe size of 3/8 inch considering the available high heat resistant and high strength materials and conventional construction techniques for seamless pipe.
Going to smaller diameters would require eliminating pipe sizes from the selection and restricting the availability to standard tube sizes, and also eliminating the high heat resistant and high strength materials from the selection. The other factor in the design decision was to consider the constructability of an absorber tube based receiver that will allow conventional pipe fit up and welding techniques.
Ultimately, the sCO2 operating conditions still produced pipe wall stress high enough to limit the life of the solar receiver in the order of 1,000 hours due to high temperature material creep. This outcome is suitable for short lived experimental work but may not be suitable for commercial long lived projects. Building a commercially viable sCO2 solar receiver would require the selection of costly very high strength and creep resistant materials, or a receiver design that allows economic replacement of parts during the plant life, or the development of alternative receiver designs and construction techniques.
Transitional hemodynamics in intracranial aneurysms — Comparative velocity investigations with high resolution lattice Boltzmann simulations, normal resolution ANSYS simulations, and MR imaging
Authors: Jain Kartik , Jiang Jingfeng , Strother Charles , Mardal Kent‐André 
Published: November 2016

PurposeBlood flow in intracranial aneurysms has, until recently, been considered to be disturbed but still laminar. Recent high resolution computational studies have demonstrated, in some situations, however, that the flow may exhibit high frequency fluctuations that resemble weakly turbulent or transitional flow. Due to numerous assumptions required for simplification in computational fluid dynamics (CFD) studies, the occurrence of these events, in vivo, remains unsettled. The detection of these fluctuations in aneurysmal blood flow, i.e., hemodynamics by CFD, poses additional challenges as such phenomena cannot be captured in clinical data acquisition with magnetic resonance (MR) due to inadequate temporal and spatial resolutions. The authors’ purpose was to address this issue by comparing results from highly resolved simulations, conventional resolution laminar simulations, and MR measurements, identify the differences, and identify their causes.MethodsTwo aneurysms in the basilar artery, one with disturbed yet laminar flow and the other with transitional flow, were chosen. One set of highly resolved direct numerical simulations using the lattice Boltzmann method (LBM) and another with adequate resolutions under laminar flow assumption were conducted using a commercially available ANSYS Fluent solver. The velocity fields obtained from simulation results were qualitatively and statistically compared against each other and with MR acquisition.ResultsResults from LBM, ANSYS Fluent, and MR agree well qualitatively and quantitatively for one of the aneurysms with laminar flow in which fluctuations were <80 Hz. The comparisons for the second aneurysm with high fluctuations of > ∼ 600 Hz showed vivid differences between LBM, ANSYS Fluent, and magnetic resonance imaging. After ensemble averaging and down‐sampling to coarser space and time scales, these differences became minimal.ConclusionsA combination of MR derived data and CFD can be helpful in estimating the hemodynamic environment of intracranial aneurysms. Adequately resolved CFD would suffice gross assessment of hemodynamics, potentially in a clinical setting, and highly resolved CFD could be helpful in a detailed and retrospective understanding of the physiological mechanisms.
Local filtration based scatter correction for cone‐beam CT using primary modulation
Authors: Zhu Lei 
Published: November 2016

PurposeExcessive scatter contamination fundamentally limits the image quality of cone‐beam CT (CBCT), hindering its quantitative use in clinical applications. The author has previously proposed an effective scatter correction method for CBCT using primary modulation. A Fourier transform‐based algorithm (FTPM) was implemented to estimate scatter from modulated projections, with a few limitations including the assumption of uniform modulation frequency and magnitude that becomes less accurate in the presence of beam‐hardening and other nonideal effects. This paper aims to overcome the above drawbacks by developing a new algorithm for the primary modulation method with improved accuracy and reliability.MethodsIncident x‐ray intensities for each detector pixel with and without the interception of the modulator blocker are estimated from a modulated flat‐field image. A new signal relationship is then developed to obtain a first scatter estimate from a modulated projection using a spatially varying modulation distribution. The method empirically adjusts the effective modulation magnitude for each projection ray to account for the beam‐hardening effects. Estimated scatter signals with high expected errors are discarded in the generation of the final scatter distribution. The author proposes a technique of local filtration to accelerate major portions of the signal processing, and the new algorithm is referred to as local filtration based primary modulation (LFPM).ResultsThe study on the Catphan® 600 phantom shows that LFPM effectively removes scatter‐induced cupping artifacts on CBCT images and reduces the CT image error from 222 to 15 HU. In addition, the image contrast on eight contrast rods of the phantom is enhanced by a factor of 2 on average. On an anthropomorphic head phantom, LFPM reduces the CT image error from 153 to 18 HU and eliminates the streak artifacts observed on the result of FTPM with substantially improved image uniformity. On the Rando® phantom, LFPM reduces the CT image error from 278 to 4 HU around the object center.ConclusionsAs compared with the previously developed FTPM algorithm, LFPM enhances the imaging performance by using a more flexible data processing framework that does not require projection data downsampling or uniform modulation frequency and magnitude. It also becomes possible to discard suspicious scatter estimate values prior to the generation of a final scatter distribution and to model the beam‐hardening effects on modulation for improved scatter estimation accuracy. The presented research further exploits the potential of the primary modulation method on scatter correction and facilitates its clinical adoption in CBCT imaging.