bluuebunny/crossref_metadata_2025 huggingface dataset:
Simulation, Analysis and Systems Engineering of a Hybrid-Electric Race Car
Authors: White Darris L. , McKisson J. E. , Barott William C. , Czlapinski Craig , Kuss Michael , Sabatini Vincent
Published: June 2009

For the past two years, Embry-Riddle has participated in the SAE Formula Hybrid competition. As part of the competition, a team of students analyze, design, and build a fully functional hybrid-electric race car. As an academic competition, the event is designed to allow a wide variety of system configurations and fuel choices. In order to optimize the vehicle characteristics, simulate vehicle performance, and build control laws, the design team created a Simulink model of the race car. As a recently created design competition, the SAE Formula Hybrid event offers an opportunity for both design innovation and system engineering. To develop a concept for the competition, the ERAU team developed detailed simulations of the vehicle in Simulink. Since the competition allows a variety of energy storage devices, engines, fuels, driveline configurations, and control systems, the development of a system dynamics model was not straight-forward. Further, system components for this project are constrained by some rules and practical constraints. The vehicle configuration was selected to be a parallel hybrid using a 250cc gasoline engine and 7.2kW DC motor with 1500F ultra-capacitor energy storage, with an unusual control strategy. The results of the Simulink model were used to predict how this vehicle configuration compares to other design choices including alternative fuels, energy storage devices and control strategies. The performance of the actual vehicle at the 2008 SAE Formula Hybrid competition, which occurs May 2008, will be presented at the conference.
The DSMC-IP Simulation of Microchannel Cross Flow Over a Staggered Array of Square Cylinders
Authors: Kursun U. , Kapat J.
Published: June 2009

A numerical simulation is performed to study two-dimensional cross flow over a staggered array of square cylinders in a microchannel using the non-isothermal Information Preservation (IP) method. The IP method works concurrently with the Direct Simulation Monte Carlo (DSMC) eliminating statistical noise from the DSMC results at low flow speeds. Pressure boundary conditions at the inlet and outlet based on the characteristic theory implemented. This study will form a base for our future particle-atomistic hybrid computations.
Solar H2 Production From a Two-Step Water Splitting Process With Metal (Fe, Ni) Doped Ceria
Authors: Kaneko H. , Naganuma Y. , Taku S. , Ouchi K. , Hasegawa N. , Tamaura Y.
Published: June 2009

Solar H2 production by the two-step water splitting process with thermochemical reaction has been proposed to convert solar energy into chemical energy. We succeeded in repeating the cyclic two-step water splitting process composed of the O2-releasing and H2-generation reactions with metal (Fe, Ni) doped ceria. The metal doped ceria with low content of metal ion (Fe3+, Ni2+) formed a solid solution with fluorite-type structure between ceria (CeO2) and metal oxide (Fe2O3, NiO). The empirical formula of the solid solution was Ce1-αMαO2−δ (M = Fe, Ni), and it was assumed that the high reactivity on the two-step water splitting process was due to an oxygen deficiency in the solid solution. The metal doped ceria with different Ce:M mole ratio (Ce:M = 0.97:0.03–0.7:0.3) was prepared through the combustion method. The two-step water-splitting process with metal doped ceria proceeded at 1673K for the O2-releasing reaction and at 1273K for the H2-generation reaction by irradiation of an infrared imaging lamp for a solar simulator. The amounts of H2 gas evolved in the H2-generation reaction with Fe-doped ceria and Ni-doped ceria with different Ce:M (M = Fe, Ni) mole ratio were 0.97–1.8 and 1.7–2.5 cm3/g, respectively, and the evolved H2/O2 ratios were approximately equaled to 2 of the stoichiometric value. The amounts of H2 and O2 gases evolved in the two-step water splitting process varied with the Ce:M mole ratio in the metal doped ceria. It was suggested that the O2-releasing and H2-generation reactions with metal doped ceria was repeated with the reduction and oxidation of Ce4+-Ce3+ enhanced by the presence of Fe or Ni ions. Furthermore, the O2-releasing reaction with Ni-doped ceria proceeded under a high O2 partial pressure atmosphere (pO2 = 0.05 atm) and at the temperature of 1773K. The progress of the O2-releasing reaction under a high pO2 indicates that metal doped ceria can be applicable for the rotary-type solar reactor developed by Tokyo Tech group for solar H2 production.
Simultaneous Production of H2 and O2 With Rotary-Type Solar Reactor (Tokyo Tech Model) for Solar Hybrid Fuel
Authors: Tamaura Y. , Kaneko H. , Naganuma Y. , Taku S. , Ouchi K. , Hasegawa N.
Published: June 2009

The rotary-type solar reactor has been developed for solar hydrogen production with the two-step water splitting process using the reactive ceramic (Ni, Mn-ferrite). The rotary-type reactor has the rotating tubular cylinder covered on a reactive ceramic and dual reaction cells for O2-releasing and H2-generation reactions. The successive evolutions of O2 and H2 gases were observed in the O2 releasing and H2 generation reaction cells, respectively, with the prototype (small) reactor (diameter of cylinder ; 4cm). There is an upper limit for the rate of H2 gas evolution in the case of the prototype reactor because of the slow rotation rate in a small irradiation area. To confirm the practical operation of the rotary-type solar reactor with the two-step water splitting process for the simultaneous production of H2 and O2 gases, a scaled-up rotary-type solar reactor with 400cm2 of the irradiation area was fabricated (diameter; 50cm). The scaled-up reactor made of inner and outer short tubular cylinders (stainless steel) has a quartz glass window for the irradiation of reactive ceramic coated on the inner tubular cylinder (cylindrical rotor) and reaction cells were aligned in the sharing spaces between the inner and outer short tubular cylinders with gas sealing mechanisms. In the reactor, reactive ceramic coated on the inner tubular cylinder was heated up to 1800K by using the infrared imaging lamps (solar simulator) with thermal flux = 600kW/m2. The solid solution between YSZ and Ni-ferrite was used as reactive ceramic for the scaled-up reactor in order to prevent from sintering at a high temperature in the O2-releasing reaction, since the sintering of reactive ceramic resulted in lowering the yield of H2 gas evolution in the H2-generation reaction. The amounts of H2 and O2 gases evolved at the rotation rate of 0.3rpm were evaluated to 64cm3 and 30cm3 for 10min with the scaled-up rotary-type solar reactor, respectively, which were much larger than those with the prototype reactor. The simultaneous evolutions of H2 and O2 gases in the two-step water splitting process were repeated by employing the scaled-up reactor with the solid solution between YSZ and Ni-ferrite.
Analysis of a Combined Power and Refrigeration Cycle Working on Solar Energy
Authors: Mandal Bijan Kumar , Sadhukhan Kousik , Chowdhuri Achin Kumar , Bhowal Arup Jyoti
Published: June 2009

Thermodynamic analysis of a combined cycle producing power and refrigeration (cooling) effect simultaneously using solar energy has been analyzed. The working substance of the cycle is a binary mixture of ammonia and water. The effect of variation of absorber pressure, boiler pressure, boiler temperature and superheater temperature on the turbine work, refrigeration (cooling) effect and net output has been investigated. For different conditions of the above variables, the first law efficiency, the second law efficiency and the exergy efficiency of the cycle have been investigated. Since the ammonia water mixture boils at varying temperatures, Lorenz cycle instead of Carnot cycle is considered as the ideal cycle for this analysis. It is observed that the first law and the second law efficiencies are maximum under the same working conditions, but the exergy efficiency is maximum at some other working conditions. The maximum values of the first law, the second law and the exergy efficiencies are found to be 21.72%, 27.30% and 62.53% respectively.
A Domestic Solar/Heat Pump Heating System Incorporating Latent and Stratified Thermal Storage
Authors: Trinkl Christoph , Zo¨rner Wilfried , Hanby Vic
Published: June 2009

Both solar and heat pump heating systems are innovative technologies for sustaining ecological heat generation. They are gaining more and more importance due to the accelerating pace of climate change and the rising cost of limited fossil resources. Against this background, a heating system combining solar thermal collectors, heat pump, stratified thermal storage and water/ice latent heat storage has been investigated. The major advantages of the proposed solar/heat pump heating system are considered to be its flexible application (suitable for new and existing buildings because of acceptable space demand) as well as the improvement of solar fraction (extended solar collector utilisation time, enhanced collector efficiency), i.e. the reduction of electric energy demand for the heat pump. In order to investigate and optimise the heating system, a dynamic system simulation model was developed. On this basis, a fundamental control strategy was derived for the overall coordination of the heating system with particular regard to the performance of the two storage tanks. In a simulation study, a fundamental investigation of the heating system configuration was carried out and optimisation derived for the system control as well as the selection of components and their dimensioning. The influence of different parameters on the system performance was identified, where the collector area and the latent heat storage volume were found to be the predominant parameters for system dimensioning. For a modern one-family house, a solar collector area of 30m2 and a latent heat store volume of 12.5m3 are proposed. In this configuration, the heating system reaches a seasonal performance factor of 4.6, meaning that 78% of the building’s and users’ heat demand are delivered by solar energy. The results show that the solar/heat pump heating system can give an acceptable performance using up-to-date components in a state-of-the-art building.
Diesel Replacement Model for Dual Diesel-Natural Gas Engines Under Urban Traffic Operation
Authors: Bermejo Fabio A. , Corredor Lesme A.
Published: June 2009

The amount of Diesel (DI) that can be replaced by Natural Gas (NG) in turbocharged Diesel vehicles converted to dual operation and under urban traffic conditions is determined by the rapid changes of engine loads, which also limits the thermodynamic performance of turbochargers. Turbochargers control the air flow that enters to the engine at every single moment of its operation, and therefore supplies the Oxygen (O2) required for burning the fuels involved in the combustion process. This investigation models the energy consumption of a diesel engine operating in dual fuel mode in urban traffic conditions of Barranquilla, Colombia. This model is based on experimental studies of transient states of Turbocharged Diesel Engines and on recent research relating to the conversion of diesel engines to dual mode. Due to the absence of a standard test cycle for the city, this investigation uses a common driving behavior profile registered in 2006 with an urban bus Chevrolet B-70 with a Caterpillar 3126 Engine. It was determined that the greater replacement percentage was about 85% at maximum load and at cruising speeds, due to the air flow supplied by the compressor. The opposite effect was found at transient states; the absence of air is because of the turbocharger performance when the vehicle is leaving the stand-by condition.
Adaptive Control of Indoor Thermal Environments Using Fan Coil Units
Authors: Srivastava Viraj , Gu Yun , Archer David
Published: June 2009

The work described in this paper relates to advanced control systems, specifically designed for heating, ventilation and air conditioning in office buildings. This work specifically focuses on the use of state of the art fan coil units with advanced instrumentation and control. The premise of the work is that control systems can be significantly enhanced by using real-time data from a distributed sensor network deployed in the building. Specifically, the performance of control systems can be improved by augmenting predictive (feed-forward) control operations with techniques to improve the accuracy of models. A control algorithm for heating, ventilating and air-conditioning systems is described in this paper that integrates an advanced feedforward control algorithm with conventional feedback control. This paper further contains a description of a functional prototype used to demonstrate the proposed control algorithm for indoor thermal environmental control. The test-bed used in this work — the Robert L Preger Intelligent Workplace (IW), at Carnegie Mellon University, involves a large number of variables and hence a complex control task, i.e., the test bed contains multiple sources of thermal energy, and multiple constraints and disturbances — both measurable and immeasurable. The algorithms demonstrated in this test-bed are expected to perform satisfactorily on other environments with smaller number of variables. This paper contains a description of experiments that were performed to validate the comfort and energy benefits of increased sensing using fan coil units that are in installed in two spaces in the IW.
Turning CO2 Capture On and Off in Response to Electric Grid Demand: A Baseline Analysis of Emissions and Economics
Authors: Cohen Stuart M. , Rochelle Gary T. , Webber Michael E.
Published: June 2009

Coal consumption accounted for 36% of America’s CO2 emissions in 2005, yet because coal is a relatively inexpensive, widely available, and politically secure fuel, its use is projected to grow in the coming decades [1]. In order for coal to contribute to the U.S. energy mix without detriment to an environmentally acceptable future, implementation of carbon capture and sequestration (CCS) technology is critical. Techno-economic studies of CCS have demonstrated its large expense due to substantial energy requirements and capital costs. However, such analyses typically calculate cost indicators using static plant performance parameters that are assumed to be constant over plant lifetime. That is, CO2 capture systems are generally assumed to capture a constant percentage of CO2 from power plant flue gas and consume a particular amount of plant gross generation capacity. Such studies do not consider dynamic plant operation that may result from diurnal and seasonal variations in electricity supply and demand, nor do they capture the economic desire to minimize CO2 emissions costs while maximizing profits by selling electricity at high price times. In this study, CO2 capture systems are analyzed in a grid level dynamic framework by considering the possibility of turning capture systems off during peak system load to regain generation capacity lost to the energy requirement of CO2 capture. This practice eliminates the costs of building additional generation capacity to make up for CO2 capture energy requirements, and it allows plant operators to benefit from selling more electricity during high price time periods. Dynamic CO2 capture operation is particularly suited to post-combustion (PC) CO2 absorption, a leading capture technology that, unlike other capture methods, offers the ability for flexible or on/off operation. This paper presents a case study on the Electric Reliability Council of Texas (ERCOT) electric grid of baseline cost and CO2 emissions estimates associated with different strategies of using on/off CO2 capture operation to satisfy peak electricity demand. It compares base cases of no CO2 capture and “always on” capture with scenarios where capture is turned off during: 1) peak load hours every day of the year, 2) days of the year of system peak load, and 3) system peak load hours only on seasonal peak load days. The study considers the implications of installing PC CO2 capture on all coal-fired plants in the ERCOT grid to better understand if on/off operation is desirable and which operational strategy may be the most economically viable under a policy of constrained CO2 emissions.
Offshore Wind Shear Estimations for Wind Power Assessment
Authors: Stewart Susan W.
Published: June 2009

Appropriate wind shear estimates are extremely important when assessing any regions’ wind power resource. Wind shear is used not only to estimate wind velocity at wind turbine hub heights other than the data collection height, but also as a siting tool to compare the wind resources in different locations when wind data are not available at a consistent height. Models for wind shear over land, as well as simple models for wind shear over open water have been found to correlate poorly with offshore wind data. This is thought to be partially due to the effect of changing wave conditions on wind shear as well as differences in thermal effects over bodies of water. In this study, offshore wind data from the South Atlantic Bight region is used to estimate the offshore wind shear conditions in this area. Data sets include collocated 10 m and 50 m meteorological data as well as wave data, all taken over a three and a half year time period. Offshore wind shear assessments from other studies are analyzed and compared to the current study as well.
Flow Distribution in the External Manifold of SOFC Stack
Authors: Qu Zuopeng , Aravind P. V. , Verkooijen Adrian , Dekker Nico
Published: June 2009

In this paper fluid dynamic behaviors of cathode gas flow in an external gas manifold of a planar solid oxide fuel cell (SOFC) stack are simulated to investigate the overall pressure variation and flow distribution. External manifold models are built in three dimensions for a 60-cell planar SOFC stack. Cell units of the stack are treated as porous media with appropriate resistances, which were determined by the previous results of cell modeling. In order to simplify this model, electrochemical reactions, heat and mass transport phenomena are ignored inside cells. The flows of cathode gas in the external manifolds of stack are modeled by means of computational fluid dynamics (CFD) methods. A commercial CFD package “Fluent” was used for geometry creation, grids generation of flow volume interiors, solving mass, momentum equations, plotting computational results. The detailed results of pressure variation and flow distribution of gases in the stack were achieved. The effects of different designs and parameters such as a gas distributor inside the external manifold, the permeability of porous media in cells and cathode gas feeding rate on gas distribution and pressure variation are studied. Comparison of different cases is carried out by the modeling results. Modeling results show for the proposed stack design in this paper the additional gas distributor located in the center of the inlet manifold and a rise of resistance in cells can respectively enhance the uniformity of flow distribution over 60 cells.
Fencing in Green: Intellectual Property Protection of Developments in Sustainability and Energy Efficient Systems
Authors: Cannuscio Robert E.
Published: June 2009

The increasing interest in recent years in energy efficiency and sustainability has generated a wealth of new innovations. Whether it is improved systems for generating energy from wind or water, new biofuels, or methods for increasing energy production from conventional fossil fuels, such innovations require expenditure of considerable research and development money. Failure to take measures to protect those innovations leave a company’s treasures open for others to use. While some feel that no protection should be granted on methods and devices that are designed to heal our Earth, the law was developed to encourage companies to invest in research. As it is, a large number of companies have already sought Intellectual Property protection for the advances they have conceived. Automotive companies have been protecting hybrid and hydrogen developments for many years. Other fields, such as solar power and wind generation, have seen a recent increase in patent applications on new developments. Navigating through these developments is becoming more and more complex as companies seek not only to protect devices that they have brought to market, but also improved concepts and advanced stages of research. Many companies blindly spend vast sums of money researching advances in a particular field, only to find out that another company has placed an Intellectual Property obstacle that inhibits bringing the advanced technology to market. Recent cases, including those from the Supreme Court have significant impact on how and whether new technology can be protected. This paper explains why patenting of green technology is beneficial to our society and some important things that companies involved in sustainability and energy advances need to know to protect themselves in this new green tinted world.
Modeling Solar Impacts on Hydrogen Production From Electrolysis
Authors: Campbell Mark R. , Deshmukh Sachin S. , Boehm Robert F. , Hurt Rick
Published: June 2009

A model is presented to simulate the energy production from a solar photovoltaic (PV) array in Southern Nevada and its energy produced for hydrogen production at a hydrogen filling station. A solar PV array composed of four single axis tracking units provides power to a Proton Exchange Membrane (PEM) electrolyzer, which produces hydrogen that is stored on site for use in hydrogen converted vehicles. The model provides the ability to predict possible hydrogen production at the site, as well as the amount of hydrogen required to sustain a prescribed level of vehicle usage. Together, these results made it possible to determine the energy required to produce sufficient hydrogen to sustain the vehicles, and the percentage of that energy generated by the solar PV array. For an average year in Las Vegas and a travel requirement of 57 miles/day, this percentage was found to be 33 percent. This simulation has the potential to be modified for different locations, array size, amount of storage, or usage requirement.
30-Year Life Cycle Cost of Solar Based Domestic Hot Water Systems for Ontario
Authors: Gill Gurjot S. , Fung Alan S.
Published: June 2009

The heating of water for domestic purposes presently accounts for 24 percent of Canadian residential energy consumption (Natural Resources Canada, 2006). This energy demand is primarily met by conventional sources such as electricity, natural gas and oil. Recent changes in fuel availability and price as well as environmental concerns lead consumers to give further consideration to the use of solar energy for heating water. The objective of this paper is to simulate the different domestic hot water (DHW) systems to examine their fuel consumption, greenhouse gases (GHG) emissions, life cycle costs and pay back periods. In this case study, seventeen different DHW systems were simulated using TRNSYS as simulation engine. These include solar-based models (with electric and natural gas backup tanks), electric and natural gas tank models (with and without gray water heat recovery), on-demand and combo-boiler systems. This paper will discuss three solar-based systems in detail, however their result comparison with other systems will be discussed. Three different solar-based systems are: I) Solar pre-heat with .56 efficiency natural gas back up tank; II) Solar pre-heat with .94 efficiency electric back up tank; III) Timers (off during peak times 7am till 10 pm) with solar pre-heat and electric (.94 efficiency) secondary. Results indicate that solar alternative having timers with solar pre-heat and electric secondary gives best results in terms of annual fuel consumption ($93) and GHG emissions (266 kg). However on demand modulating gas combo boiler (0.78 efficiency) with gray water heat recovery (0.6 efficiency) has best 30-year life cycle cost ($12332).
Modeling of Ultra Superheated Steam Gasification in Integrated Gasification Combined Cycle Power Plant With Carbon Dioxide Capture
Authors: Pei Peng , Kulkarni Manohar
Published: June 2009

Integrated Gasification Combined Cycle (IGCC) is believed to be one of the most promising technologies to offer electricity and other de-carbon fuels with carbon capture requirement as well as to meet other emission regulations at a relatively low cost. As one of the most important parts, different gasification technologies can greatly influence the performance of the system. This paper develops a model to examine the feasibilities and advantages of using Ultra Superheated Steam (USS) gasification technology in IGCC power plant with carbon dioxide capture and storage (CCS). USS gasification technology converts coal into syngas by the endothermic steam reforming reaction, and the heat required for this reaction is provided by the sensible heat in the ultra superheated steam. A burner utilizes synthetic air (21% O2 and 79% H2O) to burn fuel gas to produce the USS flame for the gasification process. The syngas generated from USS gasification has a higher hydrogen fraction (more than 50%) then other gasification processes. This high ratio of hydrogen is considered to be desired for a “capture-ready” IGCC plant. After gas cleanup and water gas shift reaction, the syngas goes to the Selexol process for carbon dioxide removal. Detailed calculations and analysis are performed to test the performance of USS gasification technology used in IGCC generation systems. Final results such as net output, efficiency penalty for CO2 capture part, and net thermal efficiency are calculated and compared when three different coal types are used. This paper uses published data of USS gasification from previous research at the University of North Dakota. The model also tries to treat the IGCC with carbon dioxide capture system as a whole thermal system, the superheated steam used in USS gasification can be provided by extracting steam from the lower pressure turbine in the Rankine Cycle. The model will make reasonable use of various waste energies and steams for both mechanical and chemical processes to improve the performance of the plant, and incorporate CO2 capture system into the design concept of the power plant.
Ammonia as a Green Fuel for Transportation
Authors: Zamfirescu Calin , Dincer Ibrahim
Published: June 2009

In this paper, the potential benefits and technical advantages of using ammonia as a green fuel for transportation are analyzed based on performance indicators including the system effectiveness, the driving range, fuel tank compactness, and the cost of driving per km. Similar to hydrogen, ammonia is a synthetic product that can be obtained thermally, physically, chemically or biologically either from fossil fuels, biomass, or other renewable sources and can be used as a clean fuel. The refrigeration effect of ammonia is another advantage of it and is included in the efficiency calculations. The cooling power represents about 7–10% from the engine power, being thus a valuable side benefit of ammonia’s presence on-board. If the cooling effect is taken into consideration, the system’s effectiveness can be improved by about 20%. It is shown that if a medium size hydrogen car converted to NH3, it becomes more cost effective per driving range as low as CN$3.2/100 km.
Life Cycle Assessment of Hydrogen Production Using Nuclear Energy: An Application Based on Thermochemical Water Splitting
Authors: Lubis Luthfi L. , Dincer Ibrahim , Rosen Marc A.
Published: June 2009

A life cycle assessment (LCA) of nuclear-based hydrogen production using thermochemical water splitting is conducted. The copper-chlorine thermochemical cycle is considered, and the environmental impacts of the nuclear and thermochemical plants are assessed. Environmental impacts are investigated using CML-2001 impact categories. The nuclear plant and the construction of the hydrogen plant contribute significantly to the total environmental impacts. The environmental impacts of operating the hydrogen production plant contribute much less. Changes in the inventory of materials or chemicals needed in the thermochemical plant do not affect significantly the total impacts. Improvement analysis suggests the development of more sustainable processes, particularly in the nuclear plant and construction of the hydrogen production plant.
Modeling, Simulation and Optimization of a Solar System for Water Heating and Absorption Cooling
Authors: Vargas J. V. C. , Ordonez J. C. , Hovsapian R. , Dias F. G.
Published: June 2009

A cogeneration system consisting of a solar concentrator, a cavity-type receiver, a gas burner, a thermal storage reservoir, a hot water heat exchanger, and an absorption refrigerator is devised to simultaneously produce heat (hot water) and cooling (cold chamber). A simplified mathematical model, which combines fundamental and empirical correlations, and principles of classical thermodynamics, mass and heat transfer, is developed. The proposed model is then utilized to simulate numerically the system transient and steady state response under different operating and design conditions. A system global optimization for maximum performance in the search for minimum pull-down and pull-up times is performed with low computational time. Appropriate dimensionless groups are identified and the results presented in normalized charts for general application. The minimum pull-down and pull-up times, found with respect to the optimized operating parameters are sharp and, therefore important to be considered in actual design. As a result, the model is expected to be a useful tool for simulation, design, and optimization of solar energy systems of the type presented in this work.
Thermodynamic Performance of a Photovoltaic System
Authors: Joshi Anand S. , Dincer Ibrahim , Reddy Bale V.
Published: June 2009

In this paper, an attempt is made to investigate the thermodynamic characteristics of a photovoltaic (PV) system based on exergy. A new efficiency is developed that is useful in studying the PV performance and possible improvements. Exergy analysis is applied to a PV system and its components, in order to evaluate the effect of various parameters e.g., voltage, current, area of the PV panel, fill factor and ambient temperature on exergy efficiency. Effect of solar radiation on power conversion efficiency is also evaluated.
Determination of Some Thermodynamic Parameters for a Hybrid Solar-Hydrogen System
Authors: Yilanci Ahmet , Dincer Ibrahim , Ozturk Harun Kemal
Published: June 2009

In this paper, we undertake a study to investigate the performance of a hybrid photovoltaic-hydrogen system through energy and exergy efficiencies, improvement potential. This will help identify the irreversibilities (exergy destructions) for performance improvement purposes. Energetic and exergetic renewability ratios are also introduced for grid dependent hybrid energy systems. A case study is presented to highlight the importance of the thermodynamic parameters and show them using some actual and theoretical data. Three different energy demand options from photovoltaic panels to the consumer are identified and considered for the analysis. The minimum and maximum overall energy and exergy efficiencies of the system are calculated based on these options. It is found that the overall energy efficiency values of the system vary between 0.88% and 9.7% while minimum and maximum overall exergy efficiency values of the system are 0.77% and 9.3%, respectively. The monthly improvement potential of the system is also studied to investigate the seasonal performance.
Research on Different Domestic Energy Consumption Patterns Based on Heat Pump and Their Exergy Analysis
Authors: Lu Shuang , Wu Jingyi
Published: June 2009

In Chinese market, many homes use heat pump systems for heating and cooling. Domestic hot water is usually provided by a domestic water heater making use of electricity, natural gas or solar energy, which is known for its great energy costs. These systems consume much energy and increase the total cost of the required domestic energy. A new system combining heat pump with water heater is proposed in this paper, and it is named domestic energy system. The system can realize the provision of space heating, cooling and domestic hot water throughout the year. Based on the different types of heat pumps and water heaters, domestic energy consumption patterns are divided into five categories: heat pump and gas-fired water heater system, heat pump and solar water heater system, heat pump and electricity water heater system, heat pump and heat pump water heater system, and domestic energy system. This study describes and compares all of the above-mentioned systems including energy and exergy analysis. Results showed that the domestic energy system can save energy and provide good economy.
Exergy Analysis of an Indirectly-Fired Combined Cycle Power Generation System
Authors: Chui Kin F. , Gnanapragasam Nirmal V. , Reddy Bale V. , Prasad Ramesh C.
Published: June 2009

A natural gas fired combined cycle power plant with indirectly-fired heating for additional work output is investigated in the current work. The mass flow rate of coal for the indirect firing mode in circulating fluidized bed combustor is estimated based on fixed natural gas input to the topping combustor. The effects of pressure ratio, gas turbine inlet temperature, inlet temperature to the topping combustor on the exergetic performance of the combined cycle configuration are analysed. The use of coal in indirect-firing mode reduces with increase in turbine inlet temperature due to increase in the use of natural gas. The exergetic efficiency increases with pressure ratio up to the optimum pressure and it also increase with gas turbine inlet temperature. The exergy destruction is highest for the circulating fluidized bed combustor (CFBC) followed by the topping combustor. The analyses show that the indirectly fired mode of the combined cycle offers better performance but with higher exergy destruction and the opportunity for additional net work output by using solid fuels (coal in this case) in existing natural gas based power plant is realized.
A Simplified Graphical Model of Air Cooler Using Mollier Diagram and Implementation in a Design Tool
Authors: Esfandiari Nia Fatemeh , van Paassen Dolf
Published: June 2009

A validated heat and mass transfer model for an air cooler is developed and implemented in a design tool. The overall heat transfer coefficient is derived from the experiments, which can be written as a function of the heat transfer coefficients on the water and air side. For a good agreement between the measurements of a wet cooler and model solutions a correction in the heat transfer coefficients substantially is done. In addition, results obtained from the measurements indicate the heat transfer coefficient itself and the correlation between heat and mass transfer need to be adapted. Acceptable results are obtained when mass transfer coefficient is adjusted by a correction factor. The decrease in heat transfer is observed with increase in dehumidification and the same is concluded from the coupling of heat and mass transfer. The fins are not completely wet, which means an analogy between sensible and latent heat only exists partly. The corrected model is implemented in the studies of advanced evaporative air conditioning systems where it is used to construct a graphical model based on rules for transients in the Mollier diagram of humid air. Preliminary calculations show that it is very accurate and useful for the simulation of controlled air handling systems although it is very fast resulting of the short calculation time of the simplified models.
Solar Thermal Electric Panel (STEP): Thermal and Energy Testing
Authors: Lamson Joel A. , Baur Stuart W.
Published: June 2009

The concept of combining both solar thermal and electric systems is not new yet the limited use and further development needed has been noted by both the Department of Energy in the U.S. [1] and the EU Coordination Action PV-Catapult in Europe [2]. These reports and the university’s solar house entry in the Department of Energy’s 2005 Solar Decathlon provided the opportunity for research and development of a hybrid roof system that combined both photovoltaics with a wet solar thermal system. The main goal of this research was to design and develop a hybrid roof system based on previous research. Once designed then build a prototype model for the purpose of performance analysis with the final stage being the implementation in the university’s solar house entry into the 2005 solar decathlon. This paper discusses the hybrid roof design and performance analysis. The design and development was initialized by a group of students and advisors from both the University of Missouri-Rolla and Crowder College with the intent to use the hybrid system as part of the solar houses in the upcoming solar decathlons. Previous research studies on hybrid roof systems have shown increased performance however the differences in the systems studied vary in their setups and use of materials. In the case of this study a series of copper tubes were integrated into a metal seam roof with an amorphous silicon panel encased in low iron glass. This experiment encompassed almost 160 square feet of hybrid Solar Thermal Electric Panel (STEP) system panels and performance data acquired was used for input to computer simulation software to optimize the system for application. Based on experimental tests the STEP system yielded overall efficiency of 50%. This is compared to a separate thermal and electric system with an estimated 26% for the same roof area. The glazed versus unglazed analysis yielded a glazed panel reducing the PV collection by 23% yet increasing the thermal collection by approximately 200%. In conclusion this paper will discuss experimental performance analysis on the STEP system thermal and overall outcomes.
Potential of Industrial Solid Wastes as an Energy Source and Gaseous Emissions Evaluation in a Pilot Scale Burner
Authors: Floriani Silvia L. , Virmond Elaine , Althoff Christine Albrecht , Moreira Regina F. P. M. , Jose´ Humberto J.
Published: June 2009

Biomass is currently used as an alternative energy source in some industries. Due to problems with disposal of wastes, using biomass as an energy source is economically and environmentally attractive. In this work seven wastes from textile and food industry were characterized and their gaseous emissions resulting from their combustion in a pilot unit were measured. The aim of this paper is to evaluate the usage of industrial wastes as an energy source taking into account their composition and gaseous emissions when submitted to combustion tests. Gaseous emissions were compared to limits imposed by Brazilian and international current legislations. Volatile organic compounds (VOC) were analyzed by GC-MS and their content values were expressed as total organic carbon (TOC). Four combustion tests were carried out in a cyclone combustor and all TOC emissions were below regulations limits. CO, CO2, NOx, CxHy and SO2 were also measured. Chemical properties showed that the volatile matter values of all biomass were high what indicate that the solids burn rapidly and some biomass presented high levels of sulphur and consequently high levels of emission of SO2 when burned. The lower heating values ranged from 14.22 to 22.93 MJ.kg−1. Moisture content and particulate matter (PM) were measured during the combustion tests and showed effective combustion conditions. Thermogravimetric analysis of the biomasses showed ignition temperatures and maximum burning rate which were compared to other papers data. The usage of these biomasses as an energy source is possible however gas treatment would be required specially if the solid presents high levels of sulphur and chlorine.
Evolution of the Transition to a World Driven by Renewable Energy
Authors: Fronk Brian M. , Neal Richard , Garimella Srinivas
Published: June 2009

The world’s energy supplies will continue to be pressured as population grows and the standard of living rises in the developing world. A move by the rest of the world towards energy consumption rates on par with the United States is most probably unsustainable. An examination of population trends, current energy utilization rates, and estimated reserves shows that a major worldwide transition to renewable resources is necessary in the next one hundred years. This paper examines one possible scenario of how energy usage and renewable power generation must evolve in this time period. As the global standard of living increases, energy consumption in developing nations will begin to approach those of the developed world. A combination of energy conservation and efficiency improvements in developed nations will be needed to push the worldwide energy consumption to 200 million BTU per person per year. Fossil fuel resources will be exhausted or become prohibitively expensive, necessitating the development of renewable energy resources. At this projected steady state population and energy consumption, the required contribution of each type of renewable resource can be calculated. Comparing these numbers to the current renewable capacities illustrate the enormous effort that must be made in the next century.
A High Standard Isolated Insolated Photovoltaic Egyptian Safari Rest Red Sea Area
Authors: Fahmy Faten H.
Published: June 2009

Where renewable energy sources, solar, hydro, wind are available the remote communities and businesses can be provided with the most reliable and affordable source of electrical energy. This paper presents a model of safari rest contains all the necessary services for the interested tourists who visit the safari Sinai desert. The PV energy system provides the rural energy needs of remote communities. A photovoltaic renewable energy system is designed to feed the global Ac and Dc electrical required load of this safari rest. The benefits of photovoltaic renewable energy at rural applications are its versatility and convenience. This model of safari rest must be taken in consideration by Egyptian Government as it will provide the tourism plane by new interested tourism field which put a big spot on Red sea area: El Ghordaka.
Predicting Phase-Change Rate in PEFC Gas Diffusion Layer
Authors: Basu Suman , Wang Chao-Yang , Chen Ken S.
Published: June 2009

Water and heat are produced in the cathode catalyst layer of a polymer electrolyte fuel cell (PEFC) due to the oxygen-reduction reaction. Efficient water removal from the gas diffusion layer (GDL) to the flow channel is critical to achieve high and stable PEFC performance. Water transport and removal strongly depend on local temperature because the saturation concentration of water vapor rises rapidly with temperature, particularly in the temperature range of practical interest to PEFC applications. Detailed investigations of two-phase flow in the GDL have been reported in the literature, but not on the rate of phase change – either from liquid to vapor as in the case of evaporation or from vapor to liquid as in the case of condensation. In the present work, a two-phase, non-isothermal numerical model is used to elucidate the phase-change rate inside the cathode GDL of a PEFC. Results computed from our model enable a basic understanding of the phase-change processes occurring in a PEFC.
Storage of DMFC MEA at Extreme Temperatures
Authors: Krewer Ulrike , Park Junyoung , Lee Jinhwa , Cho Hyejung
Published: June 2009

This paper investigates the change in performance of DMFC membrane electrode assemblies (MEAs) after storage at −10°C and 60°C under different experimental conditions. It highlights the importance of methanol concentration, an MEA’s material properties such as membrane material and catalyst loading, as well as the reactivation procedure. Storage at 60°C and concentrations below 1M methanol had no negative effect on MEA performance while storage at 60°C in a 4 M methanol solution could cause a severe performance decrease. Application of a reverse current for 10 s to a MEA which was affected by such storage was found to reinstall original performance. The effect of storage at −10°C on MEA performance strongly depends on MEA properties. MEAs are grouped into three different categories with regard to suitability for low temperature storage: not affected, reversibly affected, and irreversibly affected. The reversibly affected MEAs could be instantly and completely reactivated by reverse current. MEA materials such as various hydrocarbon membranes and high catalyst loadings as well as the manufacturing methods CCM (catalyst coated on the membrane) and CCS (catalyst coated on the substrate) were found to be principally suitable to build MEAs tolerant to storage at −10° C.
Water Crossover Reduction in DMFC Utilizing Hydrophobic Anode MPL
Authors: Shaffer Christian E. , Wang Chao-Yang
Published: June 2009

Reducing the water crossover from anode to cathode is an important goal for direct methanol fuel cell (DMFC) technology, especially if highly concentrated methanol fuel is to be used. A well-documented way to reduce this water loss to the cathode side is by using a hydrophobic cathode microporous layer (MPL). Recently, however, it has been demonstrated that in addition to a cathode MPL, the use of a hydrophobic anode MPL further reduces the water loss to the cathode. In this work, we use a two-phase transport model that accounts for capillary induced liquid flow in porous media to explain physically how a hydrophobic anode MPL acts to control the net water transport from anode to cathode. Additionally, we perform a case study and show that a thicker, more hydrophobic anode MPL with lower permeability is most effective in controlling the net water transport from anode to cathode.
A Catalyst Layer Flooding Model for Polymer Electrolyte Fuel Cells
Authors: Mukherjee Partha P. , Wang Chao-Yang
Published: June 2009

It is widely recognized that the performance degradation and the limiting current behavior in polymer electrolyte fuel cells (PEFC) are mainly attributed to the excessive build up of liquid water in the cathode side and the resulting flooding phenomena. Liquid water blocks the open pore space in the catalyst layer (CL) and the gas diffusion layer (GDL) leading to hindered oxygen transport and covers the electrochemically active sites in the CL thereby rendering reduced catalytic activity. The CL flooding therefore plays a crucial role in the overall PEFC performance limitation. In order to elucidate the primary mechanisms of liquid water removal out of the CL, the factors affecting CL flooding and to discern the role and contribution of CL flooding on the overall PEFC voltage loss, a CL flooding model has been developed. The flooding model is based on a simplified structure-wettability representation of the PEFC CL and a physical description of water and heat balance along with electrochemical performance analysis. The model shows that the evaporation mechanism, depending upon the cell operating temperature and the GDL thermal conductivity, plays a crucial role in the CL flooding behavior and the cell performance.