Water recovery in a fuel cell system

Patent metadata

Field	Value
Publication number	US-2016359180-A1
Application number	US-201515120729-A
Country	US
Kind code	A1
Filing date	Feb 18, 2015
Priority date	Feb 24, 2014
Publication date	Dec 8, 2016
Grant date	—

Abstract

A fuel cell system comprises a fuel cell stack with a cathode exhaust outlet coupled to a cathode exhaust conduit. A condenser is provided in the cathode exhaust conduit for extracting water from a cathode exhaust stream in the cathode exhaust conduit. A compressor is disposed in the cathode exhaust conduit between the cathode exhaust outlet and the condenser and an expander is disposed downstream of the condenser for recovering energy from the condenser exhaust stream. By providing compressor and expander stages on either side of the condenser, the condenser performance can be enhanced by higher pressure operation independent of the fuel cell pressure. The parasitic load of this pressurised operation of the condenser is reduced by recovering the energy from the exhaust stream.

First claim

1 . A fuel cell system comprising:
a fuel cell stack having a cathode exhaust outlet coupled to a cathode exhaust conduit; a condenser in the cathode exhaust conduit for extracting water from a cathode exhaust stream in the cathode exhaust conduit; a first compressor disposed in the cathode exhaust conduit between the cathode exhaust outlet and the condenser; and, an expander disposed downstream of the condenser for recovering energy from the condenser exhaust stream.

2 . The fuel cell system of claim 1 in which the first compressor and the expander are coupled to pass energy recovered by the expander from the condenser exhaust to the first compressor.

3 . The fuel cell system of claim 2 in which the first compressor and the expander are mechanically coupled to pass said recovered energy.

4 . The fuel cell system of claim 3 further including a motor coupled to drive the first compressor and the expander.

5 . The fuel cell system of claim 1 further including a first water separator disposed between the cathode exhaust outlet and the first compressor.

6 . The fuel cell system of claim 1 or claim 5 further including a second water separator disposed between the condenser and the expander.

7 . The fuel cell system of claim 1 further including a water storage vessel disposed between an outlet of the condenser and a cathode inlet of the fuel cell stack.

8 . The fuel cell system of claim 1 further including a second compressor coupled to a cathode inlet of the fuel cell stack.

9 . The fuel cell system of claim 8 in which the second compressor and the expander are coupled to pass energy extracted by the expander from the condenser exhaust to the second compressor.

10 . The fuel cell system of claim 8 further including a motor coupled to drive the first compressor.

11 . The fuel cell system of claim 1 further including a controller configured to vary the power supplied to the first compressor as a function of volume of water in a water recirculation circuit.

12 . A fuel cell system comprising:
a fuel cell stack having a cathode exhaust outlet coupled to a cathode exhaust conduit; a first condenser in the cathode exhaust conduit for extracting water from a cathode exhaust stream in the cathode exhaust conduit; and, a refrigeration circuit coupled to the condenser to extract heat from the first condenser.

13 . The fuel cell system of claim 12 further comprising a second, higher temperature, condenser in the refrigeration circuit configured to receive heat extracted from the first condenser.

14 . The fuel cell system of claim 12 further including an expander disposed downstream of the first condenser for extracting energy from the first condenser exhaust stream.

15 . The fuel cell system of claim 12 further including a compressor coupled to a cathode fluid inlet of the fuel cell stack, in which the compressor and the expander are coupled to pass energy extracted by the expander from the first condenser exhaust stream to the compressor.

16 . The fuel cell system of claim 15 in which the compressor and the expander are mechanically coupled to pass said extracted energy.

17 . The fuel cell system of claim 16 further including a motor coupled to drive the compressor and the expander.

18 . A fuel cell system comprising:
a fuel cell stack having a cathode exhaust outlet coupled to a cathode exhaust conduit; a condenser in the cathode exhaust conduit for extracting water from a cathode exhaust stream in the cathode exhaust conduit; and, a refrigeration circuit including an evaporator unit in the cathode exhaust conduit, downstream of the condenser, to extract heat from the cathode exhaust stream in the cathode exhaust conduit.

19 . A fuel cell system comprising:
a fuel cell stack having a cathode fluid inlet and a cathode exhaust outlet, the cathode exhaust outlet being coupled to a cathode exhaust conduit; a first compressor coupled to the cathode fluid inlet for supplying cathode fluid to the cathode of the fuel cell stack; a condenser in the cathode exhaust conduit for extracting water from a cathode exhaust stream in the cathode exhaust conduit; and, an expander disposed downstream of the condenser for extracting energy from the condenser exhaust stream, the first compressor and the expander being coupled to pass energy recovered by the expander from the condenser exhaust to the first compressor.

20 . The fuel cell system of claim 19 in which the first compressor and the expander are mechanically coupled to pass said recovered energy.

21 . The fuel cell system of claim 20 further including a motor coupled to drive the first compressor and the expander.

22 . The fuel cell system of claim 19 further including a second compressor, in series with the first compressor, to supply cathode fluid to the cathode of the fuel cell stack, the first and second compressors being separately controllable.

23 . The fuel cell system of claim 20 in which the second compressor is motor-driven.

24 . The fuel cell system of claim 1 , further including a fuel generator, and a heat conduit configured to transfer heat dissipated in the condenser to the fuel generator.

25 . The fuel cell system of claim 1 , incorporated within a combined heat and power system, the system including a heat output element coupled to the condenser.

26 . The fuel cell system of claim 12 further including a fuel generator, and a heat conduit configured to transfer heat dissipated in the condenser to the fuel generator.

27 . The fuel cell system of claim 18 further including a fuel generator, and a heat conduit configured to transfer heat dissipated in the condenser to the fuel generator.

28 . The fuel cell system of claim 12 incorporated within a combined heat and power system, the system including a heat output element coupled to the condenser.

29 . The fuel cell system of claim 18 incorporated within a combined heat and power system, the system including a heat output element coupled to the condenser.

Assignees

• Intelligent Energy Ltd

Inventors

• Adcock Paul Leonard
• Burslem Benjamin

Classifications

• H01M2008/1095

  Fuel cells with polymeric electrolytes · CPC title

• H01M8/04164 Primary

  by condensers, gas-liquid separators or filters · CPC title

• H01M8/04111

  using a compressor turbine assembly · CPC title

• H01M8/04291

  Arrangements for managing water in solid electrolyte fuel cell systems (H01M8/04119 takes precedence) · CPC title

• H01M8/04067

  Heat exchange or temperature measuring elements, thermal insulation, e.g. heat pipes, heat pumps, fins · CPC title