Abstract
In this paper, a finite time thermodynamic model of high temperature proton exchange membrane fuel cell (HT-PEMFC) is established, in which the irreversible losses of polarization and leakage current during the cell operation are considered. The influences of operating temperature, membrane thickness, phosphoric acid doping level, hydrogen and oxygen intake pressure on the maximum output power density Pmax and the maximum output efficiency ηmax are studied. As the temperature rises, Pmax and ηmax will increase. The decrease of membrane thickness will increase Pmax, but has little influence on the ηmax. The increase of phosphoric acid doping level can increase Pmax, but it has little effect on the ηmax. With the increase of hydrogen and oxygen intake pressure, Pmax and ηmax will be improved. This article also obtains the optimization relationship between power density and thermodynamic efficiency, and the optimization range interval of HT-PEMFC which will provide guidance for applicable use of HT-PEMFCs.
Highlights
In this paper, a finite time thermodynamic model of high temperature proton exchange membrane fuel cell (HT-PEMFC) is established, in which the irreversible losses of polarization and leakage current during the cell operation are considered
When theInrunning point is located in region 1, it has better performance; this paper, a finite time thermodynamic model of HT-PEMFC
Regions 3 4 5 the running point is located in the region takes the irreversibility caused by polarization and leakage current into account
Summary
HT-PEMFC converts chemical energy into electrical energy through electrochemical reaction of hydrogen and oxygen. The mass transfer mechanism of HT-PEMFC is much different from LT-PEMFC. LTPEMFC basically uses the Nafion membrane and the proton transport carrier sulfonic acid functional group can separate hydrogen ions and form hydronium ions with water molecules under humidified conditions; while in HT-PEMFCs, phosphoric acid replaces the humidified water and chemical reaction and mass transfer are based on a so-called. The chemical reaction and mass transfer within the anode, the cathode and the membrane can be expressed as Equations (1)–(3): Anode : H2 PO4− + H+ = H3 PO4. Hydrogen ions pass through proton exchange membrane and electrons flow to the cathode through the external circuit load; hydrogen ions combine with oxygen atoms and electrons at the cathode to form water molecules at relative higher temperatures over water boiling point. The total electrochemical reaction of HT-PEMFC can be formulated as Equations (4)–(6): Anode reaction : H2 → 2H+ + 2e−
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