| 1. |
- Folkesson, Anders, et al.
(författare)
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Real life testing of a hybrid PEM fuel cell bus
- 2003
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Ingår i: Journal of Power Sources. - 0378-7753 .- 1873-2755. ; 118:1-2, s. 349-357
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Tidskriftsartikel (refereegranskat)abstract
- Fuel cells produce low quantities of local emissions, if any, and are therefore one of the most promising alternatives to internal combustion engines as the main power source in future vehicles. It is likely that urban buses will be among the first commercial applications for fuel cells in vehicles. This is due to the fact that urban buses are highly visible for the public, they contribute significantly to air pollution in urban areas, they have small limitations in weight and volume and fuelling is handled via a centralised infrastructure. Results and experiences from real life measurements of energy flows in a Scania Hybrid PEM Fuel Cell Concept Bus are presented in this paper. The tests consist of measurements during several standard duty cycles. The efficiency of the fuel cell system and of the complete vehicle are presented and discussed. The net efficiency of the fuel cell system was approximately 40% and the fuel consumption of the concept bus is between 42 and 48% lower compared to a standard Scania bus. Energy recovery by regenerative braking saves up 28% energy. Bus subsystems such as the pneumatic system for door opening, suspension and brakes, the hydraulic power steering, the 24 V grid, the water pump and the cooling fans consume approximately 7% of the energy in the fuel input or 17% of the net power output from the fuel cell system. The bus was built by a number of companies in a project partly financed by the European Commission's Joule programme. The comprehensive testing is partly financed by the Swedish programme "Den Grona Bilen" (The Green Car). A 50 kW(el) fuel cell system is the power source and a high voltage battery pack works as an energy buffer and power booster. The fuel, compressed hydrogen, is stored in two high-pressure stainless steel vessels mounted on the roof of the bus. The bus has a series hybrid electric driveline with wheel hub motors with a maximum power of 100 kW. Hybrid Fuel Cell Buses have a big potential, but there are still many issues to consider prior to full-scale commercialisation of the technology. These are related to durability, lifetime, costs, vehicle and system optimisation and subsystem design. A very important factor is to implement an automotive design policy in the design and construction of all components, both in the propulsion system as well as in the subsystems.
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| 2. |
- Hedström, Lars, 1977-, et al.
(författare)
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Description and modelling of the solar–hydrogen–biogas-fuel cell system in GlashusEtt
- 2004
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Ingår i: Journal of Power Sources. - : Elsevier BV. - 0378-7753 .- 1873-2755. ; :131, s. 340-350
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Tidskriftsartikel (refereegranskat)abstract
- The need to reduce pollutant emissions and utilise the world's available energy resources more efficiently has led to increased attention towards e.g. fuel cells, but also to other alternative energy solutions. In order to further understand and evaluate the prerequisites for sustainable and energy-saving systems, ABB and Fortum have equipped an environmental information centre, located in Hammarby Sjostad, Stockholm, Sweden, with an alternative energy system. The system is being used to demonstrate and evaluate how a system based on fuel cells and solar cells can function as a complement to existing electricity and heat production. The stationary energy system is situated on the top level of a three-floor glass building and is open to the public. The alternative energy system consists of a fuel cell system, a photovoltaic (PV) cell array, an electrolyser, hydrogen storage tanks, a biogas burner, dc/ac inverters, heat exchangers and an accumulator tank. The fuel cell system includes a reformer and a polymer electrolyte fuel cell (PEFC) with a maximum rated electrical output of 4 kW(el) and a maximum thermal output of 6.5 kW(th). The fuel cell stack can be operated with reformed biogas, or directly using hydrogen produced by the electrolyser. The cell stack in the electrolyser consists of proton exchange membrane (PEM) cells. To evaluate different automatic control strategies for the system, a simplified dynamic model has been developed in MATLAB Simulink. The model based on measurement data taken from the actual system. The evaluation is based on demand curves, investment costs, electricity prices and irradiation. Evaluation criteria included in the model are electrical and total efficiencies as well as economic parameters.
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| 3. |
- Johansson, Kristina, et al.
(författare)
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The Effect of Drive Cycles on the Performance of a PEM Fuel Cell System for Automotive Applications
- 2001
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Ingår i: Proceedings, ATTCE 2001-Automotive and Transport Technology Congress and Exhibition. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. ; , s. 417-426
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Konferensbidrag (refereegranskat)abstract
- The purpose of this system study was to compare the performance and fuel consumption of a pure fuel cell vehicle ( i.e. with no battery included) with an internal combustion engine (ICE) vehicle of similar weight in different drive cycles. Both light and heavy duty vehicles are studied. For light duty vehicles, the New European drive cycle, NEDC [70/220/EEC], the FTP75 [EPA] and a Swedish driving pattern from the city of Lund [ Ericsson, 2000 ] are utilised. The fuel consumption for these drive cycles was compared with ICE vehicles of similar weight, an Ibiza Stella 1.4 (year 2000) from Seat and a Volvo 960 2.5 E sedan (year 1995). For heavy duty vehicles, urban buses in this study, two drive cycles were employed, the synthetic CBD14 and the real bus route 85 from Gothenburg, Sweden. It can be concluded that marked improvements in fuel economy can be achieved for hydrogen-fuelled light and heavy duty vehicles. The fuel consumption of a small fuel cell vehicle was 50% less than the corresponding ICE vehicle in both the NEDC and the FTP75. With proper dimensioning of the system components, e.g. the engine, further reductions in fuel consumption can be achieved. The range of more than 500 km with 5 kg of hydrogen in a 345 bar fuel tank was comparable to an ICE vehicle. If the pressure is raised to 690 bar, a driving range of 600 km could be achieved. As the auxiliary system counteracts the increase in fuel cell efficiency, raising the minimum operating voltage from 0.6 to 0.75 V in a 50 kW fuel cell system, provides only a 5% reduction in fuel consumption. A fuel cell bus operated in the CBD14 and the bus route 85, compared with diesel-fuelled urban bus of similar weight, demonstrates a reduction in fuel consumption of 33 and 37 % respectively.
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| 4. |
- Vernersson, Thomas, et al.
(författare)
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On-Board Hydrogen Storage for Fuel Cell Vehicle
- 2001
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Ingår i: Proceedings of the 36th Intersociety Energy Conversion Engineering Conference. ; , s. 581-588
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Konferensbidrag (refereegranskat)abstract
- Methods for onboard storage of hydrogen were evaluated for use in a fuel cell vehicle. Compressed hydrogen gas and cryogenic liquid hydrogen seem to be the two most viable options. Both these storage options were modelled, for storage of 5 kg hydrogen, to be implemented in an automotive fuel cell system simulation model. Hydrogen discharge was simulated for different values of cell stack operating pressure and temperature, using a constant rate of hydrogen release, and the power requirement for heating of the hydrogen to fuel cell stack operating temperature was calculated. The calculations show that compressed gaseous hydrogen storage requires a heating capacity of 0.72 - 1 kW for stack operating temperatures of 343-368 K. In the case of liquid hydrogen storage, heating demand for vaporisation and heating of the fuel was calculated to between 10 and 13 kW for stack operating temperatures of 343-368 K. The fuel cell stack produces surplus heat that can be used for fuel heating. Calculations show that the heat content of the cooling medium is sufficient to heat the fuel stream to approximately 20 K below stack temperature, with temperature differences in heat exchangers being the limiting factor. The radiator/compartment heating and humidifier will also extract heat from the cooling medium. However, to reach system temperature an auxiliary heat source will be required. This could be in the form of an electrical heater or a hydrogen burner. Also, for liquid hydrogen storage, a power demand arises for maintaining operating pressure inside the storage vessel during hydrogen release. This was calculated to between 13 and 28 W for the fuel cell stack operating conditions simulated, and this power demand can be supplied by directing a stream of released and heated hydrogen through a coil running inside the storage vessel.
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| 5. |
- Wallmark, Cecilia, et al.
(författare)
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A pinch and exergy analysis of the configuration of a stationary polymer electrolyte fuel cell system
- 2004
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Ingår i: Energy-Efficient, Cost-Effective and Environmentally-Sustainable Systems and Processes, Vols 1-3. - MEXICO : INST MEXICANO DEL PETROLEO. - 9684890273 ; , s. 703-715
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Konferensbidrag (refereegranskat)abstract
- In this paper, a pinch-based evaluation and a detailed exergy analysis are applied in order to evaluate the configuration of a stationary polymer electrolyte fuel cell system. The low-pressure fuel cell system includes natural gas steam reforming and is designed to supply a building with heat and power. The exergy balance is calculated from the exergy content of the flows in the system, with the condensed water taken into consideration. By introducing the heat supplied from the combustor to the pinch composite curves, the design and evaluation of the heat exchanger network is aided. The convenient presentation obtained of the energy balance and the exergy destruction points out the importance of the different losses within the 23 components in the fuel cell system and will be used as a basis for future research. The analysis makes it clear that the total efficiency of the system configuration is nearly optimised at 98 % LHV (89 % HHV), but that the electrical efficiency is low. To increase the electrical efficiency, the design of the fuel cell stack has to be improved. The only way to increase the thermal efficiency without changing any system parameters is to decrease the return temperature from the heat sink. The modelling work is described in comparison to measured data. The thermodynamic equations, including a methodology for handling condensed water, are attached to the paper.
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| 6. |
- Wallmark, Cecilia, et al.
(författare)
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Design of stationary PEFC system configurations to meet heat and power demands
- 2002
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Ingår i: Journal of Power Sources. - 0378-7753 .- 1873-2755. ; 106:02-jan, s. 83-92
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents heat and power efficiencies of a modeled PEFC system and the methods used to create the system configuration. The paper also includes an example of a simulated fuel cell system supplying a building in Sweden with heat and power. The main method used to create an applicable fuel cell system configuration is pinch technology. This technology is used to evaluate and design a heat exchanger a PEFC system working under stationary conditions, in order to find a solution with high heat utilization. The heat exchanger network for network in the system connecting the reformer, the burner, gas cleaning, hot-water storage and the PEFC stack will affect the heat transferred to the hot-water storage and thereby the heating of the building. The fuel, natural gas, is reformed to a hydrogen-rich gas within a slightly pressurized system. The fuel processor investigated is steam reforming, followed by high- and low-temperature shift reactors and preferential oxidation. The system is connected to the electrical grid for backup and peak demands and to a hot-water storage to meet the varying heat demand for the building. The procedure for designing the fuel cell system installation as co-generation system is described, and the system is simulated for a specific building in Sweden during I year. The results show that the fuel cell system in combination with a burner and hotwater storage could supply the building with the required heat without exceeding any of the given limitations. The designed co-generation system will provide the building with most of its power requirements and would further generate income by sale of electricity to the power grid.
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| 7. |
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| 8. |
- Wallmark, Cecilia, et al.
(författare)
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Technical design and economic evaluation of a stand-alone PEFC system for buildings in Sweden
- 2003
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Ingår i: Journal of Power Sources. - 0378-7753 .- 1873-2755. ; 118:02-jan, s. 358-366
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Tidskriftsartikel (refereegranskat)abstract
- This paper deals with the prerequisites for a stand-alone fuel cell system installed to avoid replacing or upgrading an ageing, distant power grid connection which only supplies a few buildings with their power demands. The importance of sizing the included components in the energy system is presented in economic terms. The size of the fuel cell system and the energy storage system (battery, hot-water storage and hydrogen storage) are discussed in relation to the yearly distribution of the buildings' power demand. The main design idea is to decrease the size of the fuel cell system without making the battery too expensive and that the power requirements are fulfilled over test periods with decided length and power output. The fuel cell system installation is not economically viable for the presented conditions, but in the paper future feasible scenarios are presented. The calculated incomes are shown as a function of the size of the fuel cell system and energy storage, the electricity costs, the fuel costs including transportation, the prices of electricity and heat, and the fuel cell system costs and efficiencies. The main factor in the system's economic performance is the fuel price, which contributes more than half the costs for the fuel cell system-based energy system. The cost of the power grid is also determining for the result, where the distance to the main power grid is the important factor. The evaluation is performed from the utility company's point of view.
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| 9. |
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