Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N11/00—Investigating flow properties of materials, e.g. viscosity, plasticity; Analysing materials by determining flow properties
  • G01N11/02—Investigating flow properties of materials, e.g. viscosity, plasticity; Analysing materials by determining flow properties by measuring flow of the material
  • G01N11/04—Investigating flow properties of materials, e.g. viscosity, plasticity; Analysing materials by determining flow properties by measuring flow of the material through a restricted passage, e.g. tube, aperture
  • G01N11/08—Investigating flow properties of materials, e.g. viscosity, plasticity; Analysing materials by determining flow properties by measuring flow of the material through a restricted passage, e.g. tube, aperture by measuring pressure required to produce a known flow
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
  • H01M8/04082—Arrangements for control of reactant parameters, e.g. pressure or concentration
  • H01M8/04186—Arrangements for control of reactant parameters, e.g. pressure or concentration of liquid-charged or electrolyte-charged reactants
  • H01M8/04194—Concentration measuring cells
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/30—Hydrogen technology
  • Y02E60/50—Fuel cells

Definitions

• the invention relates to a method for determining the alcohol concentration in the alcohol / water mixture of fuel cells operated with this mixture, in particular direct methanol fuel cells.
• the invention further relates to a device for performing this method.
• a measuring device for determining the concentration of low molecular weight alcohols, such as methanol, in water or acids is known from EP 0 684 469 A1.
• This meter has a porous anode for the electrochemical oxidation of alcohol, one
• Cathode for the electrochemical reduction of oxygen an ion-conducting membrane arranged between the anode and cathode and a diffusion-limiting membrane, which is arranged on the side of the anode facing away from the ion-conducting membrane.
• the measuring device which essentially represents a fuel cell, is arranged in the fuel line, for example, and is kept potentiostatically at a defined cell voltage. Depending on the alcohol concentration, a current flows through this fuel cell, the size of which can be used to infer the concentration using a calibration curve. Such a procedure is relatively complex since current and voltage have to be measured or checked.
• DMFC Direct Methanol Fuel Cell
• the fuel methanol is directly electrochemically oxidized, ie implemented without the intermediate step of reforming (see, for example, Shoes M. Waidhas in K. Ledjeff (ed.) "Fuel cells: development, technology, application", CF Müller Verlag GmbH, Heidelberg 1995, pages 137 to 156).
• K. Ledjeff ed.
• the object of the invention is to provide a method for determining the alcohol concentration in the alcohol / water mixture of fuel cells operated with this mixture fulfills all the requirements placed on such a determination method. Above all, it is necessary that the concentration can be determined continuously and in parallel with the operation of the fuel cells or the stack, and that no disturbances occur due to carbon dioxide present in the electrolyte.
• the fuel is an alcohol.
• the alcohol is in particular methanol, ethanol, propanol or glycol.
• the method according to the invention takes advantage of the fact that the viscosity of an alcohol / water mixture depends significantly on the composition of the mixture, i.e. the viscosity changes with the alcohol content.
• the viscosity at 20 ° C. with a methanol content of 0 to 16% by mass increases from 1.0 to 1.5 (see: CRC Handbook of Chemistry and Physics, 69th edition, 1988, page D-238).
• the invention applies Hagen-Poiseuille's law when determining the alcohol concentration (in particular in the anode circuit of direct methanol fuel cells).
• the constriction is built directly into the anode circuit and the alcohol / water mixture is pressed through the constriction by means of the circulating pump, which already has the value dV / dt (flow rate). In this embodiment, however, the entire mixture has to be conveyed through the constriction, which could mean an increased expenditure of energy.
• the methanol / water mixture has a temperature in the range from 80 to 110 ° C., which could have an unfavorable effect on the viscosity differences.
• Amount of alcohol / water mixture must be pressed through the narrow point. This small amount, which is a has lower heat capacity, can be thermostatted to low temperatures if necessary. In this embodiment, however, an additional measurement of the flow rate (dV / dt) of the liquid in the bypass must be carried out.

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• Life Sciences & Earth Sciences (AREA)
• Chemical & Material Sciences (AREA)
• Immunology (AREA)
• Pathology (AREA)
• Analytical Chemistry (AREA)
• Biochemistry (AREA)
• General Health & Medical Sciences (AREA)
• General Physics & Mathematics (AREA)
• Physics & Mathematics (AREA)
• Health & Medical Sciences (AREA)
• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Sustainable Development (AREA)
• Sustainable Energy (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Fuel Cell (AREA)

Applications Claiming Priority (3)

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• 1999
  • 1999-09-24 DE DE19945931A patent/DE19945931A1/de not_active Ceased
• 2000
  • 2000-09-12 CA CA002385640A patent/CA2385640A1/en not_active Abandoned
  • 2000-09-12 EP EP00967565A patent/EP1218955A1/de not_active Withdrawn
  • 2000-09-12 JP JP2001527386A patent/JP2003510787A/ja not_active Withdrawn
  • 2000-09-12 WO PCT/DE2000/003168 patent/WO2001024297A1/de not_active Application Discontinuation
• 2002
  • 2002-03-25 US US10/105,850 patent/US6536262B2/en not_active Expired - Fee Related

Non-Patent Citations (1)

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