bluuebunny/crossref_metadata_2025 huggingface dataset:
A Solar Powered Microreactor for Hydrogen Production by Methanol Reforming
Authors: Zimmerman Rau´l , Morrison Graham , Rosengarten Gary
Published: June 2009

Proton exchange membrane fuel cells (PEMFC) are good candidates for portable energy sources with a fast response to load changes, while being compact as a result of their capability to provide a high power density. Hydrogen constitutes the fuel for the PEMFC and can be obtained in situ to avoid transportation and safety problems. An efficient method to produce hydrogen is by methanol steam reforming in a micro-reactor, an endothermic reaction for which the highest efficiency occurs between 250°C and 300°C. Different methods have been used to reach and maintain these temperatures, including electrical heaters and exothermic reactions. We propose to use solar energy to increase the efficiency of the micro-reactor while taking advantage of a free, renewable energy source. The micro-channels, where the water-methanol mixture flows, are insulated from the surroundings by a thin vacuum layer coated with a selective material. This coating has a high absorptance for short wavelength incoming radiation and low emmitance for infrared radiation, reducing the heat losses. By using these coated insulation layers, the fluid temperature in the microchannels is predicted to be higher than 250°C. Hence, it is expected that the solar powered micro-reactor will produce hydrogen with a higher overall efficiency than the present reactors by taking advantage of the solar radiation.
Pre-Reformer Design and Optimization for Solid Oxide Fuel Cells
Authors: Lee Tae Seok , Chung Jacob N. , Chen Yen-Cho
Published: June 2009

We have conducted optimization for a flow process consisting typical direct internal reforming Solid Oxide Fuel Cell (SOFC) utilizing syngas with anode off gas recycling. The mass and energy balance analysis for the whole system has been carried out. Mass balance (or molar balance) analysis includes optimization for minimum fuel and oxygen consumption rates corresponding to the temperatures of pre-reformer and SOFC, the steam to carbon ratio inside the pre-reformer, recirculation ratio, and rate of CO2 capture. Studies on the reforming chemical reactions and chemical equilibria are presented. The results include CO2 adsorption in the adsorbent bed as well as recirculation. For the molar balance study, we provided methane consumption rate and overall molar balance. With the energy balance analysis, the temperature distributions in the system are calculated. We have also investigated the total system efficiency based on the first law of thermodynamics. The overall efficiency is defined as the total net power output divided by the lower heating value rate of fuel input. We also provided optimal case design parameters. Thermodynamic efficiency is mainly affected by CO2 adsorption percentage under low steam to carbon ratio region, while efficiency is mainly affected by recirculation rate under high temperature operation. In accordance with our simulation, it is recommended high SOFC temperature, moderate SC ratio, moderate CO2 adsorption and high recirculation operation.
Numerical Modeling of an Automotive Catalyst for CO and NO Emissions
Authors: Prince Juan C. , Trevin˜o Ce´sar , Diaz Mario
Published: June 2009

Catalytic combustion is useful to avoid emission of carbon monoxide and nitrogen oxides into the environment. The widespread use of the catalytic converter was the response of the automotive industry to the legislation of the countries which sets limits on pollutant emissions. The catalytic combustion of CO + NO and air mixtures in a planar stagnation-point flow over a platinum foil is studied numerically in this paper. In order to optimize the operation of the platinum converter, chemical kinetic knowledge is necessary, therefore a kinetic model is proposed, based on elementary reaction steps, that allows to describe the experiments quantitatively. The heterogeneous reaction mechanism is modeled with the dissociative adsorption of the molecular oxygen and the nondissociative adsorption of CO, together with a surface reaction of the Langmiur-Hinshelwood type and the desorption reaction of the adsorbed products, CO(s) and NO(s). The resulting governing equations based on the boundary layer theory have been numerically integrated by using Runge-Kutta method and the response curve has been obtained as a function of the initial mixture concentration. The reduction of NO and oxidation of CO in absence and presence of O2 has been investigated, and the optimal oxygen feeding into the initial mixture concentration for the maximum reduction of CO and NO was found and corresponds to the reported experimental results.
Thermodynamic Design and Comparative Analysis of Rankine, ORC and Kalina Cycles for Low-Cost, Meso-Scale Power Generation Systems
Authors: Price Suzanne E. , Mayor J. Rhett
Published: June 2009

Thermodynamic and thermoeconometric aspects of a 12.5kW residential solar-thermal power generating system are presented in this paper. The design of a meso-scale power system greatly differs from centralized power generation and as a result, this system is limited to maximum pressure of 4 MPa and maximum temperature below 500°C. The cycles under consideration are the Rankine cycle, the Organic Rankine cycle (ORC) with toluene, R123, and ethylbenzene as working fluids, and the Kalina cycle. Cycle comparisons are based off of a steady-state first law analysis of the systems under consideration. These systems are characterized to determine the system with the highest efficiency and minimum collection area. The solution that best fits a solar-thermal power system limited to 2 MPa is an ethylbenzene ORC. If the pressure is limited to 4 MPa, then the toluene ORC shows good potential.
Urban Building Energy Planning With Space Distribution and Time Dynamic Simulation
Authors: Fu Lin , Zheng Zhonghai , Di Hongfa , Jiang Yi
Published: June 2009

It’s important to deal with building energy-saving in one city level and plan the energy system from one building to one city level. It’s suggested strongly to conduct urban building energy planning in urban planning system in China. There are two main characteristics of urban building energy system. That is, firstly, the terminal building energy demand is dynamic timely, such as the heating, cooling, gas and electricity load of 8760 hours a year with peak and valley load. Secondly, the energy demand, energy sources supply, energy equipments and networks of heating, cooling, gas and electricity are distributed in urban space. It’s meaningful to conduct an innovative urban energy planning with space distribution and time dynamic simulation. In this paper, the energy planning method with space and time characteristics is presented and analyzed briefly. In the meanwhile, to meet the same energy demand in buildings, such as heating, air conditioning, gas and electricity, different energy equipments such as boiler, CHP, CCHP and heat pump based on different energy sources such as coal, gas and electricity can be planned and should be alternative among those energy sources and equipments. Thus, a well alternative urban energy system with high energy efficiency and low environmental emission should be simulated. Therefore, an urban building energy planning (UBEP) simulation tool developed by our research group is introduced. And finally, a case of energy planning in Beijing City in 2010 for heating and air conditioning system is simulated dynamically and analyzed.
Renewable Energy for Federal Land Management Agencies in Southern Nevada
Authors: France Todd , Wiemers Eric , Butterworth Stephen E. , Baghzouz Yahia , Boehm Robert F.
Published: June 2009

The National Park Service, the U.S. Fish and Wildlife Service, and the USDA Forest Service governmental agencies in southern Nevada have collaborated with the Center for Energy Research at the University of Nevada, Las Vegas to explore the feasibility of becoming energy neutral by 2010. The three federal agencies have set a goal to offset their combined annual energy demand (currently supplied by local utility companies) with an equal amount of power produced by renewable energy sources. The study results indicate that the three federal agencies above consume just over 3,000 megawatt-hours of electrical energy per year in and around the Las Vegas Valley. Upon researching various types of renewable energy, it was determined that wind, geothermal, and biomass technologies either failed to have sufficient resources available in southern Nevada or conflicted with the resource management philosophies of the federal agencies. Solar energy is the most abundant feasible source of renewable energy within the study area, and it was determined that a 1.5 megawatt fixed photovoltaic (PV) system is best suited for this project.
Space Based Solar Collectors Constructed From Lunar Materials
Authors: Renfroe David A.
Published: June 2009

Although this is not a new idea, it certainly seems to be a forgotten idea; use lunar materials to construct solar power stations at a geosynchronous orbit to beam energy via microwave to the earth’s surface at a safe 225 watts per square meter. In the 1970’s Gerard O’Neill, physics professor at Princeton and founder of Space Studies Institute, proposed this idea (1). Significant research on the establishment of lunar based mining stations, lunar launch mechanisms, low earth orbit manufacturing stations, and geosynchronous power stations was conducted. Without developing new physics principles and with less capital than was being invested in the fusion technology, a clean solar based energy generation and delivery system was possible for any point in the world. The obvious benefit would be the elimination of carbon-based fuel consumption and associated pollution, and the not-so-obvious benefit of the elimination of the 2nd law thermal pollution from any earth based energy conversion to electricity. Heat rejection from all current electricity generating facilities: coal, gas, nuclear, geothermal, even solar, reject at least two thirds of the energy converted as waste heat. By moving the heat rejection process to the extra-terrestrial environs, the useful energy available for humanity for a given temperature rise in the atmosphere, triples at least. Thus, the life style of all of humanity can practically be increased without harm to the environment. This paper will give an overview of that technology, its history from the mid 1970’s till now, and why it has not been considered in the modern context of the new “hydrogen” based energy system.
Microtechnology: A Key to System Miniaturization in Advanced Energy Recovery and Conversion Systems
Authors: Hendricks Terry J.
Published: June 2009

Energy recovery is gaining importance in various transportation, industrial process, and military applications because of rising energy costs and geopolitical uncertainties impacting basic energy supplies. Various advanced energy recovery/conversion technologies will require high-performance heat transfer characteristics to achieve energy recovery performance targets and requirements. System analysis of thermoelectric (TE) systems quantify potential power output, conversion efficiency, specific power and power flux in a unique, useful format on maximum efficiency — power maps. Lines constant specific power and power flux and their relationship to lines of constant hot side temperature and points of maximum power are demonstrated. Regions of preferred TE design are associated with not only higher conversion efficiency, but higher specific power and power flux that drives TE conversion designs towards use of microtechnology solutions. Water and He gas microchannel designs are investigated as potential solutions to achieve miniature TE energy recovery systems. Developing high-heat-flux thermal designs using microtechnology are key to enabling miniature energy recovery systems and should occur in parallel with ongoing research in advanced energy conversion materials.
Distillation Cost Calculations of Various Designs of Conventional Solar Still Systems
Authors: Shukla S. K.
Published: June 2009

On the basis of experimental results obtained during performance evaluation of five types of solar stills, kept in outdoor conditions on a single plate form, the cost of distilled water produced have been calculated by using a uniform cost analysis method. The experiments were performed at I.I.T. Delhi, India during year 2001–2002 under summer and winter, both the climatic conditions. It can be concluded that the cost of distilled water produced from a multiwick double slope solar still is lesser than other solar stills due to higher yield/hour. However for small scale purposes, multiwick single slope solar still is better option.
Experimental and Numerical Study of Mixing in a Horizontal Hot-Water Storage Tank
Authors: Aviv A. , Morad S. , Ratzon Y. , Ziskind G. , Letan R.
Published: June 2009

Thermal mixing and stratification are explored experimentally in a horizontal cylindrical tank, which simulates a storage of water heated by a solar collector. The tank is 70 cm long and 24 cm in diameter. The study is conducted in a transient mode, namely, the tank is filled with hot water, which in the course of operation is replaced by the tap water in a stratified way or by mixing. The flow rates of 2, 3, 5 and 7 liters per minute are explored. Temperature of hot water is usually about 55 °C, while the tap water is about 20 °C. In the experiments, both flow visualization and temperature measurements are used. The effects of port location and deflector installation are examined. The experimental results are presented in a dimensionless form, as the normalized outlet temperature vs. dimensionless time. Three-dimensional transient numerical simulations, done using the Fluent 6 software, provide an additional insight in the process of mixing inside the tank.
Study of Optimal Retrofit Design for the BCHP System Equipped With Gas-Fired Absorption Chillers
Authors: Cao Jiacong , Liu Cheng
Published: June 2009

In this study, the retrofit project describes the conversion of the air-conditioning system at No.4 College Building in Donghua University in Shanghai China, to a building cooling heating and power (BCHP) system. This includes the optimal retrofit design models of the BCHP system, of which the exergetic efficiency and annual costs (AC) of the system are the separate objective functions. The retrofit scheme is planned to insert gas engines as prime movers into the original system, which have adopted gas-fired absorption chillers. The solutions of the optimization problems show that such retrofit can result in a remarkable rise in exergetic efficiency but is not currently viable with current fuel prices. The contradictory solutions reveal a gap between the current energy prices system of the country and the present energy situation. It is really an urgent task to reform the energy prices system in China. Further investigation gives the critical lines of which each divides the coordinate plane of natural gas-electric prices into 2 parts, viz., of benefit and deficit. It is found if the electric price rises to a certain extent, say a rise of USD0.0238, the retrofit will reach both a positive benefit and a remarkable increase in exergetic efficiency. Discussion and conclusions have been given and may be helpful for other similar retrofit projects that aim to both energy saving and benefits.
Low-Cost Pyrometric Temperature Measurement in Concentrated Sunlight With Emissivity Determination
Authors: Crane Nathan B.
Published: June 2009

A method for correcting pyrometric temperature measurements of high temperature objects with unknown emissivity is presented. The method also estimates surface emissivity a the pyrometer wavelengths. It is particularly useful for correcting errors due to reflected light in solar heating applications. The method requires two or more narrow band pyrometers and can be applied to low-cost commercial instruments. The method analyzes the temperature measurements of multiple pyrometers operating at different wavelengths across a range of sample temperatures to solve for the surface emissivities that minimize the differences in temperature measurements. The temperature measurements are corrected using the new emissivities values. Simulated temperature data with both random noise and systematic errors is used to assess the robustness of the analysis method. When applied to temperature data from a solar furnace, it is shown to significantly decrease the difference in the temperature measurements of two single-color pyrometers. This method provides a potential low cost solution for pyrometric temperature measurement of solar-heated objects.
A Thermodynamic Similarity Framework for Assessment of Working Fluids for Solar Rankine Power Generation
Authors: Sunter Deborah A. , Carey Van P.
Published: June 2009

Numerous earlier studies have compared the merits of different working fluids for use in Rankine power systems. Most often, however, these have considered a limited number of specific fluids for which the needed thermodynamic properties are known. In the investigation summarized here, the Redlich-Kwong fluid model was used to develop a thermodynamic similarity framework that can be used as a comparative model for evaluating the performance of Rankine cycle working fluids. This can be viewed as a reduced order model that, based on thermodynamic similarity, quantifies the characteristics of the working fluids in terms of a single dimensional coordinate space defined by the choice of critical temperature. The advantage of this framework is that it allows exploration of the performance advantages of working fluids for which full thermodynamic properties are not yet available. Predictions of the model for common fluids were examined and conclusions regarding optimal fluids for solar Rankine systems are discussed.
Assessment of a Biomass Gasification Co-Generation Plant Based on the UCS’s “Principles for Bioenergy Development”
Authors: Morehouse Jeffrey H. , Detwiler Kenneth W.
Published: June 2009

An assessment of the University of South Carolina’s (USC) biomass gasification plant, which produces steam and electricity, is made using the five “Guiding Principles” found in the April 2007 update of the Union of Concerned Scientists’ (UCS) Principles for Bioenergy Development document [1]. The UCS’s guiding principles are to... “help guide bioenergy development in a manner that maximizes opportunities and helps address the challenges associated with this renewable resource.” The USC biomass plant is the first commercial biomass gasification plant producing steam and electricity in the USA. It uses bark chips from the pulp wood industry as its fuel source. Gasification of the bark produces syngas which is then oxidized and used as the heat source to generate 60,000 lb/hour (maximum) of steam at 600 psig and 740 F. The steam first passes through a turbine-generator producing 1.5 MW (maximum) of electricity and then is circulated via the campus system at 115 psig and 325 F for heating and hot water use. The plant’s construction, operational conditions, and environmental and economic impacts are examined versus the five UCS guiding principles.
A Micro Heat Engine Executing an Internal Carnot Cycle
Authors: Lurie Eli , Kribus Abraham
Published: June 2009

A micro heat engine, based on a cavity filled with a stationary working fluid under liquid-vapor saturation conditions and encapsulated by two membranes, is described and analyzed. This engine design is easy to produce using MEMS technologies and is operated with external heating and cooling. The motion of the membranes is controlled such that the internal pressure and temperature are constant during the heat addition and removal processes, and thus the fluid executes a true internal Carnot cycle. A model of this Saturation Phase-change Internal Carnot Engine (SPICE) was developed including thermodynamic, mechanical and heat transfer aspects. The efficiency and maximum power of the engine are derived. The maximum power point is fixed in a three-parameter space, and operation at this point leads to maximum power density that scales with the inverse square of the engine dimension. Inclusion of the finite heat capacity of the engine wall leads to a strong dependence of performance on engine frequency, and the existence of an optimal frequency. Effects of transient reverse heat flow, and ‘parasitic heat’ that does not participate in the thermodynamic cycle are observed.
Pressurised Oxy-Coal Combustion Rankine-Cycle for Future Zero Emission Power Plants: Process Design and Energy Analysis
Authors: Gazzino Marco , Benelli Giancarlo
Published: June 2009

This paper presents the process design and the energy analysis for a coal-fired power plant based on pressurised oxycoal combustion and including carbon capture technologies. A combustion technology performing a pressurised combustion of coal in an atmosphere of O2/CO2/H2O and including flue gases recycling has been selected. Combustion and steam production occur in separated equipments and the combustor’s design allows achieving high ash removal efficiency. The Rankine cycle has been chosen as the most viable thermodynamic cycle in a short-term scenario. Oxygen required by the combustion process is supplied by a cryogenic Air Separation Unit (ASU) and a double-reheat ultrasupercritical cycle is employed with main steam conditions of 250bar/605°C and reheat steam temperatures of 605°C/620°C. All choices related to thermal cycle selection and process design have been conducted upon the principle of feasibility and reliability. In order to increase net plant efficiency both sensible and latent heat is recovered from the flue gas stream before entering the purification and compression section. By operating in pressure it becomes possible to recover a larger amount of heat than in the atmospheric case. As a result, all low pressure steam bleedings and the corresponding regenerative heat exchangers can be eliminated. Process simulation is carried out in the paper and the expected efficiency is evaluated, as well as other cycle performance parameters. Since a relevant benefit may arise from the combustion of cheap coals, the impact of burning high-ash content and low ash-fusion-temperature coals is assessed. The impact of energy penalties associated to oxygen production and the benefit arising from high heat-transfer coefficients due to the increased pressure of the flue gas are deeply investigated.
Development of a Program in Innovative and Sustainable Design of Automotive and Building Technologies
Authors: Tate Derrick , Maxwell Timothy , Flueckiger Urs Peter , Park Kuhn , Parten Micheal
Published: June 2009

This paper describes the development of a program in Innovative and Sustainable Design that focuses on transportation and building systems. Transportation and buildings consume approximately 75% of the energy used in the US and significantly contribute to the technical issues related to sustainable energy sources and the environment. The program will be organized into four areas that revolve around the nucleus of innovation, sustainability, and design processes: namely, research, educational, outreach, and collaborative arms. Research teams will design highly efficient buildings, vehicles, and mobility systems for the future. Students will learn design approaches to address the needs for energy-neutral building technologies and an efficient, environmentally friendly transportation system fueled by sustainable energy sources. Outreach efforts will recruit secondary school and community college students into engineering programs and expand visibility for the program. Collaborative projects will provide students and faculty with opportunities to work with engineers, designers, and scientists from other universities, government institutions, and industry on timely and technically important projects.
Frictional and Internal Leakage Losses in Rotary-Vane Two-Phase Refrigerating Expanders
Authors: Mahmoud A. M. , Sherif S. A. , Lear W. E.
Published: June 2009

Increasing the coefficient of performance of a vapor compression refrigeration system may be realized by utilizing work recovering expansion devices that lower the enthalpy of the refrigerant at the inlet of the evaporator. Depending on the operational and geometrical parameters of the expander, laminar and viscous two-phase leakage flow within the expander may be present. Single-phase leakage models available in the literature must then be modified or re-derived accordingly. A dynamic frictional model for the expander must also be developed for ideal operation (i.e. no internal leakage) and modified to account for internal leakage accordingly. This paper presents a comprehensive component-level model of inherent friction and internal leakage losses in a two-phase circular rotary-vane expander used in a vapor compression refrigeration system. The model establishes the performance of the expander as a function of geometric and fluid parameters. Accurate modeling and prediction of frictional and internal leakage losses is vital to being able to accurately estimate the efficiency, rotational speed, torque and power of/produced by the expander. Directions for future work are also discussed.
Parametric Estimation of Heat and Water Management Strategy Preventing Condensed Water Formation in Polymer Electrolyte Fuel Cells
Authors: Jung Hye-Mi , Lee Kwan-Soo , Um Sukkee
Published: June 2009

This work presents the comprehensive theoretical and numerical modeling efforts on the water transport phenomena in polymer electrolyte fuel cells and intends to elucidate an optimal water management strategy preventing condensed water formation in the anode and cathode channels. For a particular design of polymer electrolyte fuel cells, theoretical and numerical analyses on the inlet feed streams were conducted to set an optimal water transport strategy. The results showed that the favorable water transport scenario (half of produced water transported back to anode) requires less humidification at the gas channel inlets compared to the worst scenario (10% of the produced water diffused back to anode). It was also shown that for 80°C operation of fuel cells, the reactants should be super-saturated and the coolant temperature difference less than 5°C between the inlet and outlet has a significant effect on the humidification of reactant gases. For an optimal system, the inlet feed stream temperature and the temperature difference of the coolant should be carefully determined, considering the humidification capacity and the size of the radiator.
Performance and Emission Characteristics of Bio-Diesel as an Alternative Diesel Engine Fuel
Authors: Palit Samiddha , Mandal Bijan Kumar , Ghosh Sudip , Bhowal Arup Jyoti
Published: June 2009

Fast depletion of the conventional petroleum-based fossil fuel reserves and the detrimental effects of the pollutant emissions associated with the combustion of these fuels in internal combustion (IC) engines propelled the exploration and development of alternative fuels for internal combustion engines. Biodiesel has been identified as one of the most promising alternative fuels for IC engines. This paper discusses about the advantages and disadvantages of biodiesel vis-a-vis the conventional petro-diesel and presents the energetic performances and emission characteristics of CI engine using biodiesel and biodiesel-petrodiesel blends as fuels. An overview of the current research works carried out by several researchers has been presented in brief. A review of the performance analysis suggests that biodiesel and its blends with conventional diesel have comparable brake thermal efficiencies. The energy balance studies show that biodiesel returns more than 3 units of energy for each unit used in its production. However, the brake specific fuel consumption increases by about 9–14% compared to diesel fuel. But, considerable improvement in environmental performance is obtained using biodiesel. There is significant reduction in the emissions of unburned hydrocarbons, polyaromatic hydrocarbons (PAHs), soot, particulates, carbon monoxide, carbon dioxide and sulphur dioxide with biodiesel. But the NOx emission is more with biodiesel compared to diesel. A case study with Jatropha biodiesel as fuel and the current development status, both global and Indian, of biodiesel as a CI engine fuel have been included in the paper.
Thermodynamic Modeling of an Integrated DIR-SOFC/Biomass Gasification System
Authors: Colpan C. Ozgur , Dincer Ibrahim , Hamdullahpur Feridun
Published: June 2009

In this paper, a direct internal reforming SOFC (DIRSOFC) integrated with a downdraft biomass gasifier is modeled thermodynamically. As a case study, wood is selected as the biomass material and performance of the system at different operating temperature levels are studied. Change of the operating cell voltage, air utilization ratio, power output of the SOFC and electrical efficiency of the system with current density are investigated. Results show that operating the system at low temperature level yields higher electrical efficiency and air utilization ratio.
Zero Energy Houses and Embodied Energy: Regulatory and Design Considerations
Authors: Hernandez Patxi , Kenny Paul
Published: June 2009

Building energy performance regulations and standards around the world are evolving aiming to reduce the energy use in buildings. As we move towards zero energy buildings, the embodied energy of construction materials and energy systems becomes more important, as it represents a high percentage of the overall life cycle energy use of a building. However, this issue is still ignored by many regulations and certification methods, as happens with the European Energy Performance of Buildings Directive (EPBD), which focuses on the energy used in operation. This paper analyses a typical house designed to comply with Irish building regulations, calculating its energy use for heating and how water with the Irish national calculation tool, which uses a methodology in line with the EPBD. A range of measures to reduce the energy performance in use of this typical house are proposed, calculating the reduced energy demand and moving towards a zero energy demand building. A life-cycle approach is added to the analysis, taking into account the differential embodied energy of the implemented measures in relation to the typical house base-case, annualizing the differential embodied energy and re-calculating the overall energy use. The paper discusses how a simplified approach for accounting embodied energy of materials could be useful in a goal to achieve the lowest life-cycle energy use in buildings, and concludes with a note on how accounting for embodied energy is a key element when moving towards zero energy buildings.
A More Direct and Cost Effective Use of Wind Power for Buildings in Cold Climates
Authors: Pederson Mark , Kulkarni Manohar
Published: June 2009

In cold climates heating a home or building can consume a large amount of energy. The heating load on a building grows even larger when the cold is accompanied by wind. This paper proposes an environmentally friendly concept that offsets this load by directly and instantaneously using wind power. Current wind turbines that produce electricity have a high cost per energy unit. A large part of this cost comes from the generator, inverter, wiring, and their inefficiencies. This concept bypasses these components and creates low cost heat directly off of the turbine shaft. The heat is produced by rotating strong magnets inside a copper housing. Fields of the magnets induce a current in the copper housing which acts like a short circuit causing the energy to become heat. The heat that the housing produces can be transported by water lines or air ventilation to the building. With a promising low payback period this concept is very appealing to consumers interested in alternative energy systems. It can be added to any building design or any existing structure. The system is also maintenance free and in relation to other alternative energy systems its initial investment is very low. The turbine of choice for this concept is a Vertical Axis Wind Turbine. It performs well in industrial or residential areas even though these areas create turbulence in the wind. An experimental setup has been constructed for this concept and tested to find its performance characteristics.
Demonstration of an Energy Meter Using a Pump Flow Station
Authors: Wang Gang , Liu Mingsheng , Claridge David
Published: June 2009

Heating and cooling energy consumption measurements are critical for operations, controls, and fault detection and diagnosis of heating, ventilation and air conditioning (HVAC) systems. Generally water flow has to be measured in order to determine energy consumption in either chilled water systems or hot water systems. Economical and accurate water flow measurements are essential to develop energy meters. Since pump performance relates actual pump water flow to pump head and power, theoretically water flow through a pump can be determined by other pump performance characteristics, such as pump head and motor power. This paper presents the theoretical model of pump flow stations based on pump head and motor power, and the experiments and results of a cooling energy meter using a pump flow station developed on the chilled water system at a facility.
Operating Experience With a 240 kW Microturbine Combined Heating, Cooling and Power System
Authors: Ja¨a¨skela¨inen Hannu E. , Wallace James S.
Published: June 2009

A 240 kWe integrated microturbine chiller/heater power system was installed on the campus of the University of Toronto at Mississauga (UTM) in 2005 to provide heating or cooling in combination with electric power generation. The system consists of four 60 kWe microturbines fueled by natural gas and a 110 refrigeration ton (389 kW) lithium bromide absorption chiller that utilizes waste heat from the microturbines. The chiller can be operated in cooling mode to supply chilled water in summer for cooling, or in heating mode to supply hot water (140°F or 60°C) in winter for heating. Campus requirements for electrical power, heating and cooling are presented. Results from operating experience over a two year period 2005–2006 are presented. Recommendations are provided to guide future installations to make full use of the equipment’s potential.
Cost Optimization of a Plug-In Hybrid Electric Vehicle
Authors: Golbuff Sam , Kelly Elizabeth D. , Shelton Samuel V.
Published: June 2009

In order to decrease the use of petroleum and release of greenhouse gases such as carbon dioxide, the efficiency of transportation vehicles must be increased. One way to increase vehicle efficiency is by extending the electric-only operation of hybrid electric vehicles through the addition of batteries that can be charged using grid electricity. These plug-in hybrid electric vehicles (PHEVs) are currently being developed for introduction into the U.S. market. As with any consumer good, cost is an important design metric. This study optimizes a PHEV design for a mid-size, gasoline-powered passenger vehicle in terms of cost. Three types of batteries, Pb-acid, NiMH, and Li-ion, and three all-electric ranges of 10, 20, and 40 miles (16.1, 32.2, and 64.4 km) were examined. System modeling was performed using Powertrain Systems Analysis Toolkit (PSAT), an Argonne National Laboratory-developed tool. Performance constraints such as acceleration, sustained grade ability, and top speed were met by all systems. The societal impact of the least cost optimum system was quantified in terms of reduced carbon emissions and gasoline consumption. All of the cost optimal designs (one for each combination of all-electric distance and battery type) demonstrated more than a 60% reduction in gasoline consumption and 45% reduction in CO2 emissions, including the emissions generated from producing the electricity used to charge the battery pack, as compared with an average car in the current U.S. fleet. The least cost design for each all-electric range consisted of a Pb-acid design, including a necessary battery replacement of the battery pack twice during the 15 year assumed life. Due to the cost of the battery packs, the 10-mile all-electric range proved to be the least costly. Also, this system saved the most carbon dioxide emissions, a 53% reduction. The most fuel savings came from the PHEV40 system, yielding an 80% reduction in gasoline consumption.
Design, Simulation and Preliminary Results of an All Electric Net-Zero Energy Solar Home
Authors: Barnes Benjamin P. , Martinez Luis A. , Esram Trishan , Newell Ty A. , Chapman Patrick L.
Published: June 2009

This paper describes the mechanical systems, the DC-coupled electrical system, the simulation approach and the preliminary results of the University of Illinois entry in the 2007 Department of Energy Solar Decathlon competition. The competition showcased twenty net-zero energy solar powered houses. The University of Illinois entry was the only one that featured an all-electric design. No solar thermal collectors were used; space and water heating was accomplished primarily through heat pumps. Each of three house modules is sensibly conditioned with autonomous, custom mini-split heat pumps using all radiant and natural convection heat exchange for the interior side. Simulation methods are described and assumptions of wall and window properties, mechanical system performance and electrical system performance are disclosed. Details are provided on the theoretical analysis of internal heat transfer and the basic design of the custom mechanical system. The electrical system topology and equipment choices are presented and initial performance results are shown. Additionally, preliminary analysis is carried out on the data taken during the Solar Decathlon competition and on the observations of post-competition winter performance. The success in being awarded comfort conditioning points during the competition is discussed along with drawbacks not represented in the competition results.
An Estimation of the Performance Limits of Dry Cooling on Trough-Type Solar Thermal Plants
Authors: Deng Huifang , Boehm Robert F.
Published: June 2009

The southwestern US is an ideal location for solar power plants due to its abundant solar resource, while there is a difficulty in implementing wet cooling systems due to the shortage of water in this region. Dry cooling could be an excellent solution for this, if it could achieve a high efficiency and low cost as wet cooling. Some dry cooling systems are currently in operation, and investigations of their performance have been reported in the literature. This paper looks into the limits to the power production implicit in dry cooling, assuming that improvements might be made to the system components. Use of higher performance heat transfer surfaces is one such possible improvement. We have developed a model of a fairly typical, but simplified, solar trough plant, and simulated thermodynamic performance of this with the software Gatecycle. We have examined the power generation and cycle efficiency of the plant for the Las Vegas vicinity with conventional wet cooling and conventional dry cooling cases considered separately using this software. TMY2 data are used for this location for this purpose. Similarly, the same studies are carried out for “ideal” cooling systems as a comparison. We assumed that in the ideal dry cooling system, the condensing temperature is the ambient dry bulb temperature, and in the ideal wet cooling system, it is the ambient wet bulb temperature. It turned out that the ideal dry cooling system would significantly outperform the conventional wet cooling system, indicating the possibility of the dry cooling system being able to achieve increased performance levels with component improvements.
Thermodynamic Performance of a Gas Turbine Plant Combined With a Solid Oxide Fuel Cell
Authors: Haseli Yousef , Dincer Ibrahim , Naterer Greg F.
Published: June 2009

This paper undertakes a thermodynamic analysis of a high-temperature solid oxide fuel cell, combined with a conventional recuperative gas turbine. In the analysis the balance equations for mass, energy and exergy for the system as a whole and its components are written, and both energy and exergy efficiencies are studied for comparison purposes. These results are also verified with data available in the literature for typical operating conditions, the predictive model of the system is validated. The energy efficiency of the integrated cycle is obtained to be as high as 60.55% at the optimum compression ratio. These model findings indicate the influence of different parameters on the performance of the cycle and irreversibilities therein, with respect to the exergy destruction rate and/or entropy generation rate. The results show that a higher ambient temperature would lead to lower energy and exergy efficiencies, and lower net specific power. Furthermore, the results indicate that increasing the turbine inlet temperature results in decreasing both the energy and exergy efficiencies of the cycle, whereas it improves the total specific power output. However, an increase in either the turbine inlet temperature or compression ratio leads to a higher rate of irreversibility within the plant. It is shown that the combustor and SOFC contribute predominantly to the total irreversibility of the system; about 60 percent of which takes place in these components at a typical operating condition, with 31.4% for the combustor and 27.9% for the SOFC.
Thermodynamic Analysis of a Novel Ammonia-Water Rankine Cycle
Authors: Zamfirescu Calin , Dincer Ibrahim
Published: June 2009

In this paper we thermodynamically assess the performance of an ammonia-water Rankine cycle that uses no boiler, but rather the saturated liquid is flashed by a volumetric expander (e.g., reciprocating, centrifugal, screw or scroll type expander) for power generation. This cycle has no pinch point and thus the exergy of the heat source can be better used by matching the temperature profiles of the hot and the working fluids in the benefit of performance improvement. The second feature comes from the use of the ammonia-water mixture that offers further opportunity to better match the temperature profiles at the source and sink level. This fact brings ∼10% improvement of exergy efficiency with respect to the case when a single substance (e.g., steam) is used as working fluid. The influence of the expander efficiency, ammonia concentration and the coolant flow rate is investigated and reported for a case study. The applications of this cycle can be found in low power/low temperature heat recovery from geothermal sources, ocean thermal energy conversion, solar energy or process waste heat etc where the cycle competes with Kalina, supercritical or multi-pressure steam implementations of the Rankine cycle.
Solar Concentrating Systems Using Small Mirror Arrays
Authors: Goettsche Joachim , Hoffschmidt Bernhard , Schmitz Stefan , Sauerborn Markus , Buck Reiner , Teufel Edgar , Badstu¨bner Kathrin , Ifland David , Rebholz Christian
Published: June 2009

The cost of solar tower power plants is dominated by the heliostat field making up roughly 50% of investment costs. Classical heliostat design is dominated by mirrors brought into position by steel structures and drives that guarantee high accuracies under wind loads and thermal stress situations. A large fraction of costs is caused by the stiffness requirements of the steel structure, typically resulting in ∼20 kg/m2 steel per mirror area. The typical cost figure of heliostats is currently in the area of 150 €/m2 caused by the increasing price of the necessary raw materials. An interesting option to reduce costs lies in a heliostat design where all moving parts are protected from wind loads. In this way, drives and mechanical layout may be kept less robust thereby reducing material input and costs. In order to keep the heliostat at an appropriate size, small mirrors (around 10 cm × 10 cm) have to be used which are placed in a box with transparent cover. Innovative drive systems are developed in order to obtain a cost-effective design. A 0.5 m × 0.5 m demonstration unit will be constructed. Tests of the unit are carried out with a high-precision artificial sun unit that imitates the sun’s path with an accuracy of less than 0.5 mrad and creates a beam of parallel light with divergence less than 4 mrad.
A Simplified Model of Desiccant Wheel and Implementation in a Design Tool
Authors: Esfandiari Nia Fatemeh , van Paassen Dolf
Published: June 2009

A new class of heat and mass transfer model for a desiccant wheel has been presented and implemented in a design tool. Having studied the behavior of the system in different conditions and sensitivity studies, two physical parameters have been chosen to make simplified models or correlations. Using 1500 data of model solutions, two correlations have been made by an optimization routine in Matlab. These equations correlate outlet air conditions of a desiccant wheel to inlet air conditions of air streams and also the wheel and air speeds. The correlations are limited to be used only in the given range of air conditions and wheel speed. However, the range covers the practical situation that usually happens according to the weather data. The behavior of air conditions in Mollier diagram shows that the error for simulation of a typical cooling cycle to calculate supply air conditions is reduced with a factor of almost 3 times smaller. This shows that even in those ranges with low accuracy the correlations are useful. These simplified equations will be used in the design tools as has been presented in details in this paper.
CFD Analysis of Two-Phase Flow and Convective Heat Transfer in PEMFC Ducts
Authors: Yuan Jinliang , Zhang Huamin , Sunde´n Bengt
Published: June 2009

In this study, a three-dimensional computational method was developed to predict convective heat transfer combined with water phase change/two-phase flow in a PEMFC cathode duct. Momentum, heat transport and species equations have been solved by coupled source terms and thermo-physical properties of the multi-component mixture. Advanced boundary conditions are applied at the cathode duct external walls in the analysis, i.e., combined thermal boundary conditions of heat flux on the active surface and thermal insulation on the remaining solid walls. Moreover, effects of mass consumption and generation appearing on the active surface are implemented. The calculated results reveal that the thermal conditions at the interfaces vary along the main stream, and a big permeability of the porous layer promotes the bulk gas transport and the generated liquid water removal via the bottom interface between the flow duct and the porous layer, and a big convective heat transfer coefficient as well.
Recent Development of Micro Ceramic Reactors for Advanced Ceramic Reactor System
Authors: Suzuki Toshio , Yamaguchi Toshiaki , Fujishiro Yoshinobu , Awano Masanobu , Funahashi Yoshihiro
Published: June 2009

Ceramic reactors, which convert materials and energy electrochemically, are expected to solve various environmental problems, and use of micro reactor design was shown to realize high performance reactor with high thermal durability operable at lower temperatures. Our research project “Advanced Ceramic Reactor” supported by NEDO targets to develop new fabrication technology for such micro reactors and modules using conventional, commercially available materials. In this study, fabrication technology of micro tubular ceramic reactors have been investigated for aiming solid oxide fuel cells (SOFCs) application, such as small distributed power generators, APU for vehicles, and portable power sources. So far, micro tubular SOFCs under 1 mm diam. using doped ceria electrolyte and Ni-ceria based cermet for tubular support has been successfully developed and evaluated. The single micro tubular SOFC showed cell performance of 0.46 W/cm2 (@0.7 V) at 550 °C with H2 fuel. Bundle design for such tubular cell was also proposed and fabricated. Discussion will cover fabrication technology of single tubular SOFC and bundle, and optimization of the cell and bundle design by considering gas pressure loss and current collecting loss.