bluuebunny/crossref_metadata_2025 huggingface dataset:
Solid Sorbent Post-Combustion CO2 Capture in Subcritical PC Power Plant
Authors: Chen Qin , Rao Ashok , Samuelsen Scott
Published: October 2015

Existing coal fired power plants are expected to continue providing a significant portion of power generation and a majority of these are subcritical pulverized coal (PC) units which have higher CO2 emissions on a MWe basis due to their higher heat rates, while CO2 emissions are an increasing concern due to global pressure on limiting greenhouse gas accumulation in the atmosphere. Current state-of-the-art CO2 capture technology uses an aqueous amine solution to chemically absorb the CO2 from the flue gas and thus requires a large amount of energy for solvent regeneration. Novel solid sorbent based CO2 capture technologies are under development to capture the CO2 via physical adsorption and desorption, thereby consuming far less energy for the sorbent regeneration process. This present work is focused on retrofitting a subcritical PC power plant with solid sorbent post combustion CO2 capture technology. Thermal performance and costs are compared with an amine based CO2 capture plant as well as the plant with no CO2 capture. The design of the solid sorbent based CO2 capture system is optimized for integration to minimize plant modifications and the associated downtime. In an existing PC plant with a net power efficiency of 36.57%, use of the amine based capture reduces the net efficiency to 26.01% while with the solid sorbent based capture, the reduction in net efficiency is far less at 28.67% when 90% of the CO2 is captured. As a consequence, the increase in plant cooling duty is significantly lower for the solid sorbent CO2 capture case, with the water usage on a per MW basis being almost 17% lower than the amine based PC plant. The calculated levelized cost of electricity is increased from $60.5/MWh without CO2 capture to $124.3/MWh for amine based capture while that with the solid sorbent based capture is much lower at $115.8/MWh.
Industrial Surplus Heat Storage in Smart Cities
Authors: Chiu Justin N. W. , Martin Viktoria
Published: October 2015

Surplus heat generated from industrial sectors amounts to between 20% and 50% of the total industrial energy input. Smart reuse of surplus heat resulted from industrial sectors and power generation companies is an opportunity to improve the overall energy efficiency through more efficient use the primary energy sources. A potential solution to tackle this issue is through use of thermal energy storage (TES) to match user demand to that of the generated surplus heat. A mobile TES (M-TES) concept of transportation of industrial surplus heat from production sites to end customers has shown promising results. One commissioned demonstration project using industrial heat for swimming pool water temperature regulation in Dortmund, Germany proved the interest and attention given to this concept.

In this paper, a techno-economic case study in Sweden of transportation of surplus thermal energy to district heating in smart cities is presented. The application consists of heat storage at 110°C–130°C through the use of phase change materials (PCM) based TES, notably with use of Erythritol (90 kWh/ton) for the considered temperature range, to remote district heating network located at 48 km from the thermal energy generation site. The advantages of using latent heat based PCM are the high enthalpy density per unit volume and per unit mass, as well as the quasi-constant temperature during charging and releasing of heat. The M-TES in this study has a total storage capacity of 2.1 MWh, the optimization of charge/discharge time to the amount of stored/released energy and to that of energy transportation rate is presented in this paper. Contrary to logical thinking, it is shown through this work that under certain conditions, it is more cost-effective to operate at partial load of storage units albeit the increased number of transport trips and charge/discharge cycles.
Design and Optimization of Thermal Selective Emitters for High-Efficiency Thermophotovoltaic (TPV) Power Generation
Authors: Yuksel Anil , Heltzel Alex , Howell John R.
Published: October 2015

Thermophotovoltaic (TPV) devices are popular energy converters due to providing low noise, low thermal-mechanical stresses and portability. The conversion efficiency of TPVs is still low due to mistuned spectral properties between thermal selective emitters and the TPV cell. Using thermal selective emitters that are well-matched to the TPV cell spectrum enhances the conversion efficiency of TPVs. Several thermal selective emitters, composed of 1-D complex multilayer structures with rectangular gratings, have been proposed. Cost, fabrication and stability factors have been major problems for their application on TPV modules. In this paper, a 1-D tungsten thermal emitter is optimized which exhibits close to blackbody emittance near the band-gap of a GaInAsSb TPV cell and sharp cutoff for longer wavelengths. The emitter is at 1200K, and is designed and optimized by modeling triangular grooves to excite localized groove modes which are well-matched to the GaInAsSb TPV cell external quantum efficiency (EQE) for high efficiency energy conversion. We suggest that a quasi-monochromatic, narrow-band and coherent emitter at a frequency near the energy band-gap of the converter is an ideal source to achieve high conversion efficiency.
Study of the Lemon Drying Process Using a Solar Dryer
Authors: Terres Hilario , Chavez Sandra , Lopez Raymundo , Lizardi Arturo , Lara Araceli , Morales Juan R.
Published: October 2015

A complete study for a solar dryer is shown. In this work the lemon drying process is considered. Also, results for temperature distribution, currents lines velocities and density distribution are presented inside of the dryer chamber. Curves for dried are obtained when the lost mass of the lemon is measured. For this purpose, a digital balance is used and during several intervals of time the measures are done. A Compact Field point device of National Instrument is used to measure temperatures inside of the chamber in the dryer. Thermocouples k-type were placed in different points. By acquisition data, the values of temperature were measured for the test. By means of software (ANSYS) is discretized the inner zone and using the temperatures as boundary conditions. Solving the system defined for the equations according to the mesh defined, temperature, velocities and densities are determined. The results allowing to identify what is the behavior inside of the dryer and how the drying process happens. This way to study the drying process can be useful when the behavior inside of the chamber wants to be evaluated. In addition, this work can be useful in the design of solar dryers because allows to know how the trays can be placed to take advantage in the best way the solar energy in solar dryers.
Assessment of Different Natural Ventilation Strategies for an Educational Building on the Warm-Humid Climate of Guayaquil, Ecuador
Authors: Beltrán R. David , Kastillo Juan , Miño-Rodríguez Isabel , Naranjo-Mendoza Carlos , Ávila Carlos
Published: October 2015

Natural ventilation has been studied as an effective strategy in order to reduce energy consumption without compromising occupant’s hygrothermal comfort in warm-humid climates. However, the main concern about the current state of art in the use of Building Energy Simulation (BES) as an approach to natural ventilation is the definition of input data which usually do not represent the real state of the buildings in the studied region. Within this context, the main contribution of this research is to propose a methodology through which the real state of buildings can be evaluated. By this analysis, valid input parameters was found to exploit the capabilities of BES and CFD simulations to fulfill the main objective of this study, which is to assess the impact of natural ventilation strategies in the energy consumption of HVAC systems and occupants hygrothermal comfort. Four natural ventilation strategies were evaluated: single sided ventilation, cross ventilation, solar chimney and double façade. The results show that the exclusive use of natural ventilation is ineffective to ensure hygrothermal comfort in a building with high thermal loads in a warm-humid climate like Guayaquil. However, by using a hybrid system (natural ventilation/dehumidification and cooling) cooling energy consumption can be reduced in up to 10.6% without compromising occupant’s hygrothermal comfort. Due to the promising results regarding energy savings, further research will aim to evaluate the impact of other passive strategies in energy consumption.
Thermal Stability of Oxide-Based Solar Selective Coatings for CSP Central Receivers
Authors: Ambrosini Andrea , Lambert Timothy N. , Boubault Antoine , Hunt Andrew , Davis Danae J. , Adams David , Hall Aaron C.
Published: October 2015

Efforts at Sandia National Laboratories are addressing more efficient solar selective coatings for tower applications, based on oxide materials deposited by a variety of methods. Over the course of this investigation, several compositions with optical properties competitive to Pyromark have been identified. These promising coatings were deposited on Inconel 625 and Haynes 230 Ni alloys and isothermally aged in air at temperatures between 600–800 °C for up to 480 hours, concurrently with Pyromark®, which was used as a reference standard. At various heating times, the samples were removed from the furnace and their optical properties (solar-weighted absorptance and emittance) were measured. In addition, x-ray diffraction and scanning electron microscopy were utilized to investigate any structural or morphological changes that occurred over time with heating, in an attempt to correlate with changes in optical properties. At 600 and 700 °C, several of the coatings maintained an absorptivity > 90%. While the chemical makeup of the coating material greatly influences its optical properties, the morphology of the surface also plays in important part. A thermal sprayed coating modified using a novel laser treatment showed improved properties versus the untreated coating, on par with Pyromark™ at 600 °C, with little degradation after 480 hours. The results of aging on the optical, structural, and morphological properties of these novel coatings will be discussed.
Investigating the Potential of Urban Land Uses to Support Sustainable Energy Principles Using a Spatial Analysis Model
Authors: Gibson Sherika
Published: October 2015

The underpinning elements of sustainable communities are centered on economic security, renewable energy resources, reliable infrastructure, and ecological protection. The geomorphology of urban areas is altered due to human activity leading to change in land use characteristics and resources availability. Research has shown that global population has increased drastically over the last three decades resulting in depleted efficiency of regional resources. Because of this, obtaining sustainable energy platforms is a world-wide concern. In evaluating the ability of urban communities to support sustainable elements, both spatial and temporal influences must be considered. As a result a spatial analysis model will be used to assess the geomorphological and land use aspects of urban watersheds to support sustainable communities’ platform. These data will provide insight in essential components in need of environmental restoration that contribute to future renewable resources which can then be applied on a global scale.
Design of a Mobile Probe to Predict Convection Heat Transfer on Building Integrated Photovoltaic (BIPV) at University of Technology Sydney (UTS)
Authors: Madadnia Jafar
Published: October 2015

In the absence of a simple technique to predict convection heat transfer on building integrated photovoltaic (BIPV) surfaces, a mobile probe with two thermocouples was designed. Thermal boundary layers on vertical flat surfaces of a photovoltaic (PV) and a metallic plate were traversed. The plate consisted of twelve heaters where heat flux and surface temperature were controlled and measured. Uniform heat flux condition was developed on the heaters to closely simulate non-uniform temperature distribution on vertical PV modules. The two thermocouples on the probe measured local air temperature and contact temperature with the wall surface. Experimental results were presented in the forms of local Nusselt numbers versus Rayleigh numbers “Nu=a * (Ra)b”, and surface temperature versus dimensionless height [Ts -T∞= c*(z/h)d]. The constant values for “a”, “b”, “c” and “d” were determined from the best curve-fitting to the power-law relation. The convection heat transfer predictions from the empirical correlations were found to be in consistent with those predictions made by a number of correlations published in the open literature. A simple technique is then proposed to employ two experimental data from the probe to refine empirical correlations as the operational conditions change. A flexible technique to update correlations is of prime significance requirement in thermal design and operation of BIPV modules. The work is in progress to further extend the correlation to predict the combined radiation and convection on inclined PVs and channels.
A New Photovoltaic Module Design Paradigm: Cell Strands That Track the Sun
Authors: Diong Bill , Tippens Scott , Francis Teshaun , Herndon Marcus
Published: October 2015

A project was recently undertaken with the objective of designing a novel photovoltaic module, which encloses groups of solar cells that can track the sun. This will allow the module itself to be mounted simply at a fixed tilt but still reap the substantial energy collecting benefits presently associated only with rotating active and passive solar tracking panels, while avoiding their significant additional complexity, cost and weight. The main ultimate goal is to design such a module to collect at least 25% more energy than a similarly-sized fixed-tilt solar panel, while limiting its added production cost to less than 25%. This paper describes the module’s specific design requirements, and the analysis and design embodiments that have led to a few closely related prototypes based on bimetallic coil actuators. It also presents outdoor test (in the state of Georgia, USA) results showing that the most recent such prototypes collected just over 6% more energy than a similarly-sized fixed-tilt solar panel.
A Neural Network Based Method for Real-Time Measurement of Capacity and SOC of Vanadium Redox Flow Battery
Authors: Cao Hongfei , Zhu Xinjian , Shen Haifeng , Shao Meng
Published: October 2015

The state of charge (SOC) of Vanadium Redox Flow Battery (VRFB) plays an important role in the operation and control of the Battery system. The value of SOC can be defined as the ratio of the remaining capacity to the rated capacity of the battery. Current measurement of SOC of VRFB is limited to one certain charge-discharge circulation so the rated capacity is known and can be regarded as a constant. However, during long time cycling, the capacity of VRFB will reduce gradually to a relatively low level so that the capacity of the battery cannot be seen as the constant value of rated capacity, which makes it difficult to measure the SOC accurately in real-time operation. This work presents a neural network based method of measuring the capacity and SOC for VRFB in real time. The capacity is firstly classified into three levels in terms of the loss degree by a Probabilistic Neural Network (PNN) using the values of the voltage per second and the average power of the cell stack in any period of the circulation. The values of capacity which fall within different levels are then given by different Back Propagation Neural Networks (BPNN) trained by the battery operation values in corresponding level. Finally, the SOC can be obtained by the calculated capacity. All the networks are validated by experimental data and the results indicate that the method is suitable for the measurement of VRFB capacity and SOC in the practical application.
Simulation of Intermediate-Temperature SOFC for 60%+ Efficiency Distributed Generation
Authors: Mastropasqua Luca , Campanari Stefano , Iora Paolo , Romano Matteo Carmelo
Published: October 2015

This work proposes a process simulation of high efficiency intermediate-temperature (660–730°C) SOFC systems for promising applications in the foreseeable future distributed power generation sector. Two case-studies have been considered: the kW-scale unit proposed by Ceramic Fuel Cell Limited (CFCL), which reaches up to 68% stack DC efficiency, and the FuelCell Energy (FCE) SOFC system, where a 65% DC efficiency has been verified on a 10 kW module. Both systems can be applied to distributed generation, yielding 60%+ net electric efficiency (LHV basis) from natural gas at small scale.

This study aims at calibrating the two considered SOFC balance of plants with the Politecnico di Milano in-house software GS. Throughout a zero-dimensional model of the complete system a validation of the manufacturer’s claimed performance is possible. The general module configuration is made up of a natural gas pre-treating processor, a SOFC stack, an anodic spent fuel combustor and a waste heat recovery system for CHP applications. A pre-reforming adiabatic reactor has been proven to be an efficient choice to reduce the higher hydrocarbon chains content in the fuel stream and therefore to lessen the burden on the anodic channel, especially in terms of solid carbon deposition. The fuel is then pre-heated and, in the FCE case-study, mixed with the anodic outlet recycle; this last solution is regarded as of utmost importance for the attainment of the high overall fuel utilisation (≈80–85%) factors necessary to reach the proposed high efficiency targets, as well as to provide the steam required by the internal reforming process.

Both the considered fuel cell systems performance have been verified and their extremely high efficient operation proven, according to those reported by their manufacturers.

In addition to the process simulation, the work lays the foundations for a more thorough SOFC stack modelling throughout a 2D in-house developed software. This analysis gives valuable insights on the geometry characterisation and on the flow arrangement, as well as on their effects on cell internal temperature and composition profiles. In particular, the proposed analysis focuses on the case of a planar cross-flow arrangement, representative of the latter of the two case-studies. The understanding of the internal behaviour of the systems provides useful information to optimise the cell performance and design.
Novel Structured Electrolyte for All-Solid-State Lithium Ion Batteries
Authors: Liu Wei , Milcarek Ryan , Wang Kang , Ahn Jeongmin
Published: October 2015

In this study, a multi-layer structure solid electrolyte (SE) for all-solid-state electrolyte lithium ion batteries (ASSLIBs) was fabricated and characterized. The SE was fabricated by laminating ceramic electrolyte Li1.3Al0.3Ti1.7(PO4)3 (LATP) with polymer (PEO)10-Li(N(CF3SO2)2 electrolyte and gel-polymer electrolyte of PVdF-HFP/ Li(N(CF3SO2)2. It is shown that the interfacial resistance is generated by poor contact at the interface of the solid electrolytes. The lamination protocol, material selection and fabrication method play a key role in the fabrication process of practical multi-layer SEs.
A Supercritical CO2 Brayton Cycle Power Converter for a Sodium-Cooled Fast Reactor Small Modular Reactor
Authors: Sienicki James J. , Moisseytsev Anton , Krajtl Lubomir
Published: October 2015

Although a number of power conversion applications have been identified or have even been developed (e.g., waste heat recovery) for supercritical carbon dioxide (S-CO2) cycles including fossil fuel combustors, concentrated solar power (i.e., solar power towers), and marine propulsion, the benefits of S-CO2 Brayton cycle power conversion are especially prominent for applications to nuclear power reactors. In particular, the S-CO2 Brayton cycle is well matched to the Sodium-Cooled Fast Reactor (SFR) nuclear power reactor system and offers significant benefits for SFRs. The recompression closed Brayton cycle is highly recuperated and wants to operate with an approximate optimal S-CO2 temperature rise in the sodium-to-CO2 heat exchangers of about 150 °C which is well matched to the sodium temperature rise through the core that is also about 150 °C. Use of the S-CO2 Brayton cycle eliminates sodium-water reactions and can reduce the nuclear power plant cost per unit electrical power. A conceptual design of an optimized S-CO2 Brayton cycle power converter and supporting systems has been developed for the Advanced Fast Reactor – 100 (AFR-100) 100 MWe-class (250 MWt) SFR Small Modular Reactor (SMR). The AFR-100 is under ongoing development at Argonne National Laboratory (ANL) to target emerging markets where a clean, secure, and stable source of electricity is required but a large-scale power plant cannot be accommodated. The S-CO2 Brayton cycle components and cycle conditions were optimized to minimize the power plant cost per unit electrical power (i.e., $/kWe). For a core outlet temperature of 550 °C and turbine inlet temperature of 517 °C, a cycle efficiency of 42.3 % is calculated that exceeds that obtained with a traditional superheated steam cycle by one percentage point or more. A normal shutdown heat removal system incorporating a pressurized pumped S-CO2 loop slightly above the critical pressure on each of the two intermediate sodium loops has been developed to remove heat from the reactor when the power converter is shut down. Three-dimensional layouts of S-CO2 Brayton cycle power converter and shutdown heat removal components and piping have been determined and three-dimensional CAD drawings prepared. The S-CO2 Brayton cycle power converter is found to have a small footprint reducing the space requirements for components and systems inside of both the turbine generator building and reactor building. The results continue to validate earlier notions about the benefits of S-CO2 Brayton cycle power conversion for SFRs including higher efficiency, improved economics, elimination of sodium-water reactions, load following, and smaller footprint.
Impact of Mechanical Constraints on the Irradiation Performance of U10Mo Monolithic Mini-Plates
Authors: Mohamed Walid , Roh Hee Seok , Hofman Gerard , Medvedev Pavel G.
Published: October 2015

For the conversion of high performance research reactors to low enrichment Uranium fuel, U-Mo alloy based fuels in monolithic form were proposed. These plate-type fuels consist of a high uranium density, low enrichment uranium (LEU) foil contained within a diffusion barrier, and encapsulated within a cladding. To benchmark this new design, effects of various geometrical and operational variables on irradiation performance have been evaluated. In this work, the effects of mechanical constraints on the thermo-mechanical behavior of a plate were studied. To evaluate these effects, a selected plate from RERTR-12 experiments (Plate L1P756) was simulated. Four distinct cases which represent four distinct welding conditions were considered. Evaluation of the stress-strain fields in the fuel elements revealed that mechanical constraints may impact the plate’s performance. These constraints include (a) inlet side, (b) outlet side, (c) both inlet and outlet sides; and finally, (d) entire long edges. Results of these cases were then compared with the ideal case. The peak stress-strain magnitudes, displacement, stress and strain profiles on the fuel elements are evaluated to make a comparative assessment. The results indicated that the cases with constraints on “inlet side only” and “outlet side only” yielded lower cladding strains compared with other cases. The difference on the displacement profiles on the fuel foil was not significant. Peak stresses on the foil did not change considerably. These results imply that the mechanical constraints effects peak cladding strains, while it does not cause significant effects on the fuel behavior.
CFD Simulation and Experimental Data for a Fixed Heat Load Natural Draft Air-Cooled Heat Exchanger With Cold Inflow Mitigation
Authors: Chu Christopher C. M. , Rahman Md. Mizanur , Kumaresan Sivakumar
Published: October 2015

CFD simulation was carried out to corroborate experimental data at fixed heat load of nominally 2.3kW from a natural draft heat exchanger of face dimensions of 0.75m × 0.75m, with or without mitigation of the cold inflow at the chimney exit, where mitigation by installing wire mesh on top of the chimney has been shown by the experiments to enhance air flow rate. A chimney model was simulated at fixed heat loads in a still surrounding at ambient temperature of 30 degree Celsius and atmospheric pressure for two modes: Mode 1 and Mode 0 for with and without a flow resistor (wire mesh) respectively at the top exit. It was found that the simulation could reproduce most of the trends of the experimental data, but had a tendency to magnify the detrimental effects of cold inflow and exaggerate the remedial action of wire mesh in preventing cold inflow, as reflected by the ratio of Mode 1 to Mode 0 air mass flowrate by a factor of up to 2.36, compared to 1.50 in the experimental data. In both simulation and experiment, the average air flow rates obtained at chimney heights of 0.35m, 0.65m, 0.95m and 1.25m, showed progressive increase of air mass flow rate for all cases. Both experimental and simulated heat gain in Mode 0 were more or less constant until the highest chimney height where they showed apparent breakout upwards, whereas in Mode 1 the experimental heat gains gently reduced to a plateau while the simulated heat gains hovered at around 2.3kW. The back calculated values of Mode 0 experimental outlet temperature at between 140 to 240°C raises concern of hotspot in some electronic components by the ineffectiveness of chimney systems without cold inflow mitigation. Further experiments of similar scale with steadier control of heat flux and heating temperature, and simulating with other turbulence models in transient mode will improve understanding in both Mode 0 and Mode 1 of operation.
Analysis of CO2 Capture From Power-Plant Flue Gas Using the Membrane Gas Absorption (MGA) Method
Authors: Zhang Zhien , Yan Yunfei , Wang Junlei , Zhang Li , Chen Yanrong , Ju Shunxiang
Published: October 2015

Currently membrane gas absorption (MGA) is a novel approach for gas separation. In the present work, a wide-ranging 2D mathematical model for CO2 absorption from the N2/CO2 mixture is proposed. Single solvents [H2O, ethylenediamine (EDA), diethanolamine (DEA), monoethanolamine (MEA), piperazine (PZ)] and blended solvents [DEA/PZ] were used as the absorbents. The non-wetting mode for the membrane contactor was considered in the calculations. The effects of gas concentration and velocity, and liquid concentration and velocity on CO2 removal were observed. The simulation results were verified with the experimental data showing a good agreement. The modeling results indicate that gas concentration and velocity have a negative effect on the capture process, while liquid concentration and velocity enhance CO2 capture. Also, it is noted that PZ has the best absorption performance than other single absorbents. The chemical solvents are much better than the physical solvent for the absorption of CO2. For mixed absorbents based on amine solutions, the CO2 removal efficiency could be about 20% higher than that of the single solutions. Thus, this model could provide the optimum operating conditions for acid gas absorption in the hollow fiber membrane module. It is also proved that the MGA approach exhibits a good potential in power-plant waste gas purification.
Preheats Effect on Distributed Reaction Fuel Reforming
Authors: Scenna Richard , Gupta Ashwani K.
Published: October 2015

Conventional non-catalytic fuel reforming provides low efficiency, large amounts of char and tar and limited control on chemical composition of the syngas produced. In this paper volume distributed reaction technique is used to enhance reformate quality as compared to conventional reforming that uses non-catalytic reforming. Reforming of middle distillate fuels typically utilize preheats of 300–600°C[1,2]. This work investigates the intermediate regimes between volume distributed reaction regime and conventional flame regime for the reforming of JP8 through the chemical and mixing time scale. The results showed that reformate concentrations of fixed gases and most low molecular weight hydrocarbons changed gradually with air preheats. Reaction regime did not drastically change reformate products except for acetylene. In conventional flame regime acetylene concentration rapidly increased upon on entering the reactor.
Further Investigation of Discharge Coefficient for PTC 6 Flow Nozzle in High Reynolds Number
Authors: Furuichi Noriyuki , Terao Yoshiya , Nakao Shinichi , Fujita Keiji , Shibuya Kazuo
Published: October 2015

The discharge coefficients of the throat tap flow nozzle based on ASME PTC 6 are measured in wide Reynolds number range from Red=5.8×104 to Red=1.4×107. The nominal discharge coefficient (the discharge coefficient without tap) is determined from the discharge coefficients measured for different tap diameters. The tap effects are correctly obtained by subtracting the nominal discharge coefficient from the discharge coefficient measured. Finally, by combing the nominal discharge coefficient and the tap effect determined in three flow regions, that is, laminar, transitional and turbulent flow region, the new equations of the discharge coefficient are proposed in three flow regions.
Experimental Study of the Influence of Light Intensity on Solar ORC Power Generation System
Authors: Wang Yuping , Tang Lei , Weng Yiwu
Published: October 2015

A low temperature (<393K) solar Organic Rankine Cycle (ORC) power generation experimental facility was designed and built. The heat pipe evacuated tubular collector was selected as the solar collector. A scroll expander was used as the expander and the working fluid was R600a. The influence of light intensity variation on system performance has been studied. The results indicate that the system efficiency and thermoelectric efficiency of the experimental facility can reach to 2.2% and 4.4%, respectively. The thermoelectric efficiency and power decrease with the decrease of the heat transfer fluid temperature. There is a turn point in the variation of these performance parameters at high flow rate. The heat transfer fluid temperature at the turn point is about 75°C at the working fluid flow rate of 200L/h. The system efficiency decreases with the decrease of light intensity. There is a turn point light intensity Itpi. The system efficiency varies slowly when the light intensity is higher than Itpi. The experimental results are of great significance for the new design of low temperature solar ORC power generation system.
Heat Pump Water Heater Control Strategy Optimization for Cold Climates
Authors: Bursill Jayson , Cruickshank Cynthia A.
Published: October 2015

Commercially available heat pump water heaters (HPWH) have been used successfully in warm humid climates (southern United States), and recently, have been proven effective in replacing electric water heater technology in cooler climates within Canada. Using an air source HPWH unit within a dwelling can yield electrical coefficients of performance that are indicative of significant energy savings, but can also add an additional load to the space heating system. Current control strategies do not attempt to mitigate the heating load added to the surrounding space, and only consider the water temperature in the tank. This is because, to date, the primary application has been in sub-tropical climates where cooling is frequently beneficial. Starting in 2015, the US Department of Energy is mandating that all electric water heaters have an energy factor (unit of heat applied to hot water per unit of energy applied to the system) greater than 2, which makes technologies that utilize electrical coefficients of performance, such as HPWH technology, mandatory. To ease the inevitable transition to heat pump water heaters in lieu of electric water heaters, modified control strategies that highlight using thermal storage to reduce space heating loads must be implemented. This paper presents a study which was conducted to evaluate the performance of a commercially available HPWH with modified controls. The HPWH is first characterized experimentally under a series of different thermal conditions and draw parameters. The test tank contains a 1500 W electric auxiliary heater that provides on demand heat to the top 0.30 m (1 ft) of the tank, and a wraparound heating coil. An air source heat pump, using R-134A as the refrigerant, draws air from, and returns air to the surrounding space and provides heating to the whole tank through the coil. The tank has been tested using Canadian Standards Association draw profiles to characterize performance under different hot water demands. Electricity consumption and thermal flux is measured for each vertical tank section, and various performance metrics are calculated using energy balances. A TRNSYS model is then calibrated to the experimental data to allow for the flexibility of varying multiple parameters over various climates. Using this calibrated TRNSYS model, an optimal control strategy and tank set-points can be determined for use in cold climates. As expected from previous work, there is a decrease in performance of the heat pump when heating the tank to higher temperatures to facilitate thermal storage, but the benefits from taking advantage of shifting electrical demand (of water heating) to space heating demand can outweigh the loss of performance.
Catalytic Oxidation of Jet Fuel Surrogates in a Meso-Scale Combustor
Authors: Wierzbicki Teresa A. , Lee Ivan C. , Gupta Ashwani K.
Published: October 2015

Oxidation behavior of dodecane and two mixtures of dodecane and m-xylene (90/10 wt. % and 80/20 wt. %) over an Rh catalyst in a meso-scale heat recirculating combustor was examined to isolate the effect of aromatic content on performance. The fuel conversion, product speciation and reaction kinetics were calculated, and the global combustion behavior observed. The results showed that increasing the amount of m-xylene in the fuel increased the fuel conversion from 85% (pure dodecane) to 92% (90/10) and further to 98% (80/20). The presence of xylene also significantly increased CO2/H2O selectivity and de-creased CO/H2 selectivity. Global activation energy increased linearly with increase in xylene content, supporting that addition of aromatic species to fuel lowers the overall reactivity. The non-catalytic reaction was also simulated using Chemkin software to determine the effect of the Rh catalyst on the combustor performance. The results revealed that the catalyst promotes total oxidation over partial oxidation, and lowers the global activation energy by up to 70%.
A Study of Aerodynamics Force Evaluation of Horizontal Axis Wind Turbine (HAWT) Blade Using 2D and 3D Comparison
Authors: Munir Nazia Binte , Lee Kyoungsoo , Huque Ziaul , Kommalapati Raghava R.
Published: October 2015

The main purpose of the paper is to use Computational Fluid Dynamics (CFD) in 3-D analysis of aerodynamic forces of a Horizontal Axis Wind Turbine (HAWT) blade and compare the 3-D results with the 2-D experimental results. The National Renewable Energy Laboratory (NREL) Phase VI wind blade profile is used as a model for the analysis. The results are compared with the experimental data obtained by NREL at NASA Ames Research Center for the NREL Phase VI wind turbine blade. The aerodynamic forces are evaluated using 3-D Computational Fluid Dynamics (CFD) simulation. The commercial ANSYS CFX and parameterized 3-D CAD model of NREL Phase VI are used for the analysis. The Shear Stress Transport (SST) Gamma-Theta turbulence model and 0-degree yaw angle condition are adopted for CFD analysis. For the case study seven varying wind speeds (5 m/s, 7 m/s, 10 m/s, 13 m/s, 15 m/s, 20 m/s, 25 m/s) with constant blade rotational speed (72 rpm) are considered. To evaluate the 3-D aerodynamic effect sectional pressure coefficient (Cp) and integrated forces about primary axis such as normal, tangential, thrust and torque are evaluated for each of the seven wind speed cases and compared with the NREL experimental values. The numerical difference of values on wind blade surface between this study and 3-D results of NREL wind tunnel test are found negligible. The paper represents an important comparison between the 3-D lift & drag coefficient with the NREL 2-D experimental data. The results shows that though the current study is in good agreement with NREL 3-D experimental values there is large deviation between the NREL 2-D experimental data and current 3-D study which suggests that in case of 3-D analysis of aerodynamic force of blade surface it is better to use NREL 3-D values instead of 2-D experimental values.
Investigation on Thermal and Kinetic Characteristics During Pyrolysis and Co-Pyrolysis of Recovered Fuels Obtained From Municipal Solid Waste in China
Authors: Chen Lin , Wang Shuzhong , Zhiqiang Wu , Meng Haiyu , Zhao Jun , Zonghu Lin
Published: October 2015

Alternative fuels, such as municipal solid waste (MSW) tend to play an increasingly important role in Chinese energy supply. Gasifying fuels derived from MSW have the potential of covering a significant part of the future demand on gasification capacities. However, their pyrolysis behaviour was not clear due to that the reactions during co-pyrolysis of the MSW serval fractions have not yet been fully investigated. In this paper, thermal behavior of pork, polypropylene and their blends were investigated by thermogravimetry under pyrolysis conditions via the non-isothermal thermogravimetric analysis. The pyrolysis and co-pyrolysis kinetics characteristics of the waste samples was investigated at a temperature range of 50 to 1000 °C with the heating rate of rate of 10, 20, 40 °C·min−1 and for particle sizes less than 74 μm. The results indicated that pyrolysis rate of pork was hindered by polypropylene. Negative synergistic effects on mixture decomposition was observed. Weight loss of mixture were lower than that calculated from individual samples for pork and polypropylene. The apparent activation energy were obtained through Kissinger and Ozawa methods for the samples. The results indicated that more energy for blends to be decomposed during co-pyrolysis.
Optimization Design and Thermal Economy Analysis of the Flue Gas Treatment System in Power Plant
Authors: Tang Chunli , Li Jianbo , Qi Qingwen , Wang Chang’an , Che Defu
Published: October 2015

A novel flue gas treatment system was proposed in this paper. The system integrates the low pressure economizer (LPE) with the desulphurized flue gas heater (DFGH) for both waste heat recovery of the exhaust gas and the desulphurized flue gas heating. A model for the system was established based on the equivalent enthalpy drop theory. The thermal economic comparisons among 5 feasible connection schemes for the flue gas treatment system of a 300 MW unit were executed. The parametric analyses were also performed to evaluate the effects of the outlet flue gas temperature and the condensate temperature of the DFGH. Results indicate that the optimized flue gas treatment system can improve the thermal economy and heat the desulphurized flue gas. Better thermal economy is achieved when the LPE is connected with the high energy level feed water heater, and the low pressure extraction steam is extracted for heating desulphurized flue gas. The thermal economy decreases with the increase of the outlet flue gas temperature of the DFGH while it increases slightly with the decrease of the condensate temperature of the DFGH.
Cost Performance Tradeoff Study of Power Generation From Wind
Authors: Goudarzi Navid , Pavlak Alex
Published: October 2015

Health and environmental consequences of conventional fossil fuels are drawing more interest in expanding the use of renewable energy sources. The primary challenges in supplying the required electricity from wind are the variability, uncertainty, and the cost of electric power generation. An earlier paper presented the results of a system concept tradeoff using one-year wind/load data from Pennsylvania New Jersey Maryland Interconnection LLC (PJM). While one year results showed a wind plus natural gas system can reduce CO2 emission as much as 50% below that of an all-natural gas system with only a modest increase in system cost, typical power generation modeling extends to three years. In this work, the developed model is employed to estimate the magnitude of cost versus performance using three-year wind/load data at PJM in the United States and EirGrid in Ireland, and cost estimations published by the Energy Information Agency. The year to year variation at each region is studied and compared with each other. Also, the curtailment curve obtained from three years wind/load data is compared with that from one year to access the variance. The grid-scale storage parameter variations are studied to estimate the generation cost with storage as a function of emission levels.
Fuel Effects on Nozzle Flow and Spray Using Fully Coupled Eulerian Simulations
Authors: Bravo Luis , Xue Qingluan , Som Sibendu , Powell Christopher , Kweon Chol-Bum M.
Published: October 2015

The objective of this study is to examine the impact of single and multi-component surrogate fuel mixtures on the atomization and mixing characteristics of non-reacting isothermal diesel engine sprays. An Eulerian modeling approach was adopted to simulate both the internal nozzle flow dynamics and the emerging turbulent spray in the near nozzle region in a fully-coupled manner. The Volume of Fluids (VoF) methodology was utilized to treat the two-phase flow dynamics including a Homogenous Relaxation approach to account for nozzle cavitation effects. To enable accurate simulations, the nozzle geometry and in-situ multi-dimensional needle lift and off-axis motion profiles have been characterized via the X-ray phase-contrast technique at Argonne National Laboratory. The flow turbulence is treated via the classical k–ϵ Reynolds Average Navier Stoke (RANS) model with in-nozzle and near field resolution of 30 μm. Several multi-component surrogate mixtures were implemented using linear blending rules to examine the behavior of petroleum, and alternative fuels including: JP-8, JP-5, Hydro-treated Renewable Jet (HRJ), Iso-Paraffinic Kerosene (IPK) with comparison to single-component n-dodecane fuel on ECN Spray A nozzle spray dynamics. The results were validated using transient rate-of-injection measurements from the Army Research Laboratory at Spray A conditions as well as projected density fields obtained from the line-of-sight measurements from X-ray radiography measurements at The Advanced Photon Source at Argonne National Laboratory. The conditions correspond to injection pressure, nominal fuel temperature, and ambient density of 1500 bar, 363 K, and 22.8 kg/m3, respectively. The simulation results provide a unique high-fidelity contribution to the effects of fuels on the spray mixing dynamics. The results can lead to improvements in fuel mixture distributions enhancing performance of military vehicles.
Influence of Excess Air Factor on NOx Emissions From a 200 kW Swirl Burner
Authors: Ahmed Abdallah , Khalil Essam E. , Kayed Hatem , Hassan Mohamed M. A.
Published: October 2015

NOx formation during the combustion process occurs mainly through the oxidation of nitrogen in the combustion air (thermal NOx) and through oxidation of nitrogen with the fuel (prompt NOx). The present study aims to investigate numerically the problem of NOx pollution using a model of combustion chamber with 200 kW swirl burner utilizing propane as fuel. The importance of this problem is mainly due to its relation to the pollutants produced by boiler furnaces and gas turbines, which used widely in thermal industrial plants. Governing conservation equations of mass, momentum and energy, and equations representing the transport of species concentrations, turbulence, combustion and radiation modeling in addition to NOx modeling equations were solved together to present temperature and OH distribution inside the combustion chamber, and the NOx concentration at the combustion chamber exit, at various operating conditions of fuel to air ratio.

In particular, the simulation provided more insight on the correlation between the peak flame temperature and the thermal NOx concentration. The results have shown that the peak flame temperature and NOx concentration decrease as the excess air factor λ increases. When considering a fixed value of mass flow rate of fuel, the results show that increasing λ results in a maximum value of thermal NOx concentration at the exit of the combustion chamber at λ = 1.05. As the combustion air temperature increases, and the thermal NOx concentration increases sharply. However, when λ exceeds this value NOx concentration starts to decrease due to the combustion air temperature decrease.
Numerical Investigation of a Three-Dimensional Laminar Mixed Convection Flows in Lid-Driven Cavity for Very Small Richardson Numbers
Authors: Abo Elazm M. M. , Shahata A. I. , Elsafty A. F. , Teamah M. A.
Published: October 2015

Laminar mixed convection in a three-dimensional lid driven cavity is numerically investigated. The top lid of the cavity is moving rightwards with a constant speed at a cold temperature. The bottom wall is maintained at an isothermal hot temperature, while the other vertical walls of the cavity are assumed to be insulated. In this study the mass diffusion was not taken into account and the fluid used was air. The flow and heat transfer behavior is studied for various Richardson number ranging from 5 × 10−5 to 3 × 10−4 at a fixed Prandtl number of 0.71 through analyzing the local Nusselt number distribution at different sections inside the cavity. Lewis number Le is assumed to be unity and the buoyancy ratio parameter N is equal to zero. Computations were done using an in-house code based on a finite volume method. The results showed a good agreement with previous two dimensional studies, while the three dimensional study gives different results at different sections inside the cavity. It is observed that, the average Nusselt number “Av Nu” on top and bottom surfaces decreases for all sections inside the cavity with increasing Richardson number. A correlation was formulated for each section on both walls for “Av Nu” as a function of “Ri” with a maximum error of 7.3%.
Transient Ground Potential Rise in Gas Insulated Substations and Analysis of Effective Factors
Authors: Babaei Maziar , Abdelwahed Sherif , Babaei Mehdi
Published: October 2015

This study presents the way of implementation of transient modeling concepts which are fully analyzed in referred standards, for the purpose of evaluating the Transient Ground Potential Rise (TGPR). This is a phenomenon of 10–100kV voltages with up to 10μs duration on the grounded enclosure of Gas Insulated Substations (GIS), which may cause concern for personnel safety and problems for protection and control circuits. This paper summarizes the results of investigation for influential factors on TGPR such as different contingency conditions and grounding system models while the paper focuses on the TGPR study of “Siahbishe” 400kV gas insulated substation. The study was carried out by modeling all pieces of equipment in EMTP-RV and careful consideration of different modeling guidelines and instructions described in available standards.