Fuel cell cathode balance of plant freeze strategy

Patent metadata

Field	Value
Publication number	US-10290880-B2
Application number	US-201414260199-A
Country	US
Kind code	B2
Filing date	Apr 23, 2014
Priority date	Apr 23, 2014
Publication date	May 14, 2019
Grant date	May 14, 2019

Abstract

A system and method for a cathode subsystem in a fuel cell system. The system includes a fuel cell stack, a cathode inlet line that provides cathode air to a fuel cell stack and a cathode exhaust line that exhausts a cathode exhaust gas out of the fuel cell stack. Also included is a backpressure valve in the cathode exhaust line that is located downstream of a drip rail of the cathode exhaust line, where the drip rail includes a protrusion that prevents condensed water from building up near the backpressure valve. The drip rail further includes a sump that collects drips of condensed water from the protrusion of the drip rail. The system also includes a drain below a water vapor transfer unit that includes an orifice that is in a portion of the drain that is within the cathode exhaust line.

First claim

What is claimed is:

1. A fuel cell system with a cathode subsystem, said cathode subsystem comprising:
a fuel cell stack;
a cathode inlet line that provides cathode inlet air to the fuel cell stack;
a cathode exhaust line that exhausts a cathode exhaust gas out of the fuel cell stack; and
a backpressure valve and a drip rail positioned in the cathode exhaust line, said backpressure valve being located downstream of the drip rail in the cathode exhaust line, wherein the drip rail includes a protrusion that is positioned on an internal wall of the cathode exhaust line at a location higher than the backpressure valve, wherein an upper surface of the protrusion is slanted downwards from the internal wall in a direction towards a sump so as to redirect condensed water to an opposite side of the cathode exhaust line and prevent the condensed water from building up near the backpressure valve, wherein the sump is positioned in the cathode exhaust line between the drip rail and the backpressure valve to collect drips of the condensed water from the upper surface of the protrusion of the drip rail.

2. The system according to claim 1 further comprising a controller that is programmed to determine a temperature of the backpressure valve and to estimate liquid water near the backpressure valve, said controller performing a freeze purge strategy if the temperature and the liquid water near the backpressure valve reach predetermined threshold values.

3. The system according to claim 1 further comprising a by-pass line that selectively directs the cathode inlet air to the cathode exhaust line using a by-pass valve, said by-pass valve located near the cathode inlet line in the by-pass line, said by-pass line including at least one turn downstream of the by-pass valve that prevents water in the cathode exhaust line from back splashing against the by-pass valve.

4. The system according to claim 1 further comprising a charge air cooler and a water vapor transfer unit in the cathode inlet line, wherein the charge air cooler is located in the cathode inlet line and feeds into the water vapor transfer unit in the cathode inlet line, said charge air cooler being cooled by a coolant loop, wherein a pressure sensor is positioned on the charge air cooler such that a pressure of the cathode inlet air is measured after the air is cooled by the charge air cooler and the pressure of the cathode inlet air is measured before the water vapor transfer unit adds water to the cathode inlet air.

5. The system according to claim 4 further comprising a drain that is directly below the water vapor transfer unit, said drain including a sump that drains liquid water from the water vapor transfer unit into the cathode exhaust line through an orifice.

6. The system according to claim 5 further comprising a screen that sits in the drain directly above the orifice, wherein a portion of the drain that includes the orifice and the screen extends into the cathode exhaust line such that heat from the cathode exhaust line is able to melt ice that may accumulate at the orifice of the drain.

7. The system according to claim 6 wherein the portion of the drain that is near the screen and the orifice is made of a thermally conductive material.

8. The system according to claim 1 wherein the backpressure valve is an inverted P-valve that is located in a hill region of the cathode exhaust line.

9. A fuel cell system with a cathode subsystem, said cathode subsystem comprising:
a fuel cell stack;
a cathode inlet line that provides cathode inlet air to the fuel cell stack;
a cathode exhaust line that exhausts a cathode exhaust gas out of the fuel cell stack;
a water vapor transfer unit that transfers humidity from the cathode exhaust gas to the cathode inlet air;
a backpressure valve and a drip rail positioned in the cathode exhaust line, said backpressure valve being located downstream of the drip rail in the cathode exhaust line, wherein the drip rail includes a protrusion that is positioned on an internal wall of the cathode exhaust line at a location higher than the backpressure valve, wherein an upper surface of the protrusion is slanted downwards from the internal wall in a direction towards a sump so as to redirect condensed water to an opposite side of the cathode exhaust line and prevent the condensed water from building up near the backpressure valve, wherein the sump is positioned in the cathode exhaust line between the drip rail and the backpressure valve to collect drips of the condensed water from the upper surface of the protrusion of the drip rail;
a charge air cooler that is located in the cathode inlet line and that feeds the cathode inlet air into the water vapor transfer unit, said charge air cooler being cooled by a coolant loop, wherein a pressure sensor is positioned on the charge air cooler at a location such that a pressure of the cathode inlet air is measured by the pressure sensor after the air is cooled by the charge air cooler and the pressure of the cathode inlet air is measured before the water vapor transfer unit adds the humidity to the cathode inlet air;
a by-pass line that selectively directs the cathode inlet air from the cathode inlet line to the cathode exhaust line through a by-pass valve positioned in the by-pass line, said by-pass valve being located near the cathode inlet line in the by-pass line, said by-pass line including at least one 90° turn that is provided downstream of the by-pass valve that prevents water in the cathode exhaust line from back splashing against the by-pass valve; and
a controller that is programmed to determine a temperature at a location of the cathode subsystem and that is programmed to estimate liquid water at the location of the cathode subsystem, said controller being programmed and configured to perform a freeze purge strategy if the temperature and the estimated liquid water at the location reach predetermined threshold values.

10. The system according to claim 9 further comprising a drain that is directly below the water vapor transfer unit, said drain including a sump that drains liquid water from the water vapor transfer unit into the cathode exhaust line through an orifice.

11. The system according to claim 10 further comprising a screen that sits in the drain directly above the orifice, wherein a portion of the drain that includes the orifice and the screen extends into the cathode exhaust line such that heat from the cathode exhaust line is able to melt ice that may accumulate at the orifice of the drain.

12. The system according to claim 10 wherein at least a portion of the drain that includes the orifice and the screen is made of a thermally conductive material.

13. The system according to claim 9 further comprising a backpressure valve in the cathode exhaust line, said cathode backpressure valve being an inverted P-valve that is located in a hill region of the cathode exhaust line.

14. The system according to claim 3 wherein the by-pass line includes a plurality of 90° turns provided downstream of the by-pass valve.

15. The system according to claim 3 wherein a distance between the by-pass valve and the cathode exhaust line is at least 20 inches.

16. The system according to claim 1 wherein the drip rail is tapered.

17. The system according to claim 1 wherein the sump is shallow enough that the sump can be cleared of water while the fuel cell system is in use.

18. The system according to claim 1 wherein the drip rail can account for a 17° grade.

19. The system according to claim 1 wherein the sump can h

Assignees

• Gm Global Tech Operations Llc

Inventors

• Clingerman Bruce J
• Rogahn Aaron
• Burch Steven D
• Cartwright Michael

Classifications

• H01M2008/1095

  Fuel cells with polymeric electrolytes · CPC title

• H01M8/0432

  Temperature; Ambient temperature · CPC title

• H01M8/04201

  Reactant storage and supply, e.g. means for feeding, pipes · CPC title

• H01M8/04395

  of cathode reactants at the inlet or inside the fuel cell · CPC title

• H01M8/04179 Primary

  by purging or increasing flow or pressure of reactants · CPC title