METHOD AND SYSTEM FOR PREVENTING INJURY FROM HOT EXHAUST GAS

Abstract

In order to prevent injury from hot exhaust gas, water is condensed by a metal net in the exhaust pipe.

Claims

1.-9. (canceled)

10. A method of preventing injury from hot exhaust gas released from an exhaust system through an outlet of an exhaust pipe of a vehicle, the vehicle comprising a high temperature fuel cell system that is operating at temperatures in the range of 120-200° C. when producing electrical power, wherein the method comprises providing a wire mesh in the flow path of the exhaust gas through the exhaust system from the fuel cell to the exhaust pipe outlet, wherein the exhaust gas contains water vapor, and wherein the method comprises condensing water drops with the wire mesh for creating dried exhaust gas, and releasing the drops through the exhaust pipe and out of the exhaust pipe outlet together with the dried exhaust gas, wherein the method comprises A or B or a combination of A and B, wherein in A, a heat exchanger is provided for cooling the water vapor in the exhaust gas in the flow path to the exhaust pipe outlet and wherein the method comprises cooling the vapor to below its dew point upstream of the wire mesh in order to cause in-creased drop formation in the wire mesh; and wherein in B, the method comprises raising the dew point of the water vapor by raising the pressure of the water vapor in the exhaust system for increased condensation.

11. The method according to claim 10, wherein the fuel cell is a high temperature polymer electrolyte membrane HT-PEM fuel cell.

12. The method according to claim 10, wherein the method comprises providing the wire mesh inside the exhaust pipe of the vehicle, the exhaust pipe defining the flow path of the exhaust gas to the exhaust pipe outlet.

13. The method according to claim 10, wherein method comprises providing the wire mesh as a compressed metal mesh filter that is knitted or woven or made as a roll of metal wire sheets.

14. The method according to claim 10, wherein the method comprises providing the wire mesh with a length of between 10 mm and 10 cm when measured in the direction of the exhaust flow path, and wherein the wire mesh extends entirely across the exhaust flow path in order to prevent the water vapor to bypass the wire mesh.

15. A system for preventing injury from hot exhaust gas released from an exhaust system through an outlet of an exhaust pipe of a vehicle, the vehicle comprising a HT-PEM fuel cell system configured for operation at temperatures in the range of 120-200° C. when producing electrical power, wherein the system comprises a wire mesh in the flow path of the exhaust gas through the exhaust system from the fuel cell to the exhaust pipe outlet and the system is configured for condensing water drops by the wire mesh for creating dried exhaust gas and for releasing the drops through the exhaust pipe and out of out of the exhaust pipe outlet together with the dried exhaust gas, wherein the system comprises A or B or a combination of A and B, wherein in A, a heat exchanger is provided which is configured for cooling the exhaust gas with the water vapor in the flow path to the exhaust pipe outlet to below its dew point upstream of the wire mesh in order to cause increased drop formation in the wire mesh; and wherein in B, the system comprises means for raising the dew point of the water vapor by raising the pressure of the water vapor in the exhaust system for increased condensation.

16. The system according to claim 15, wherein the wire mesh is a compressed metal mesh filter that is knitted or woven or made as a roll of metal wire sheets and with a length of between 10 mm and 10 cm when measured in the direction of the exhaust flow path, and wherein the wire mesh extends entirely across the exhaust flow path in order to prevent the water vapor to bypass the wire mesh.

Description

DESCRIPTION OF THE DRAWING

[0026] Embodiments of the invention will be described in the FIGURES, wherein:

[0027] FIG. 1 a vehicle with a fuel cell system and an exhaust pipe comprising a wire mesh filter in the flow path of the water vapour.

DETAILED DESCRIPTION OF THE INVENTION

[0028] FIG. 1 illustrates vehicle 1 on ground 2 and containing a fuel cell 3 typically multiple fuel cells, for example as a stack of fuel cells, as part of a fuel cell system 4.

[0029] Advantageously, the fuel cell 3 is a high temperature polymer electrolyte membrane (HT-PEM) fuel cell. Typically, high temperature fuel cells operate in the temperature range of 120-200° C., and thus are producing heat as well. For example, the fuel cell 3 operates at a temperature of 170-185° C. This operation temperature is held constant by a correspondingly adjusted flow of first coolant in a cooling circuit through the fuel cell. For example, the temperature of the first coolant at the coolant inlet of the fuel cell is in the range of 160° C. to 170° C.

[0030] Apart from the fuel cells 3, the fuel cell system 4 comprises a combination of a reformer and corresponding reformer burner, and a temperature regulation system, including a cooling circuit. In addition, a power management system is provided. Fuel is provided from a fuel tank 5. For example, the fuel tank 5 contains alcohol, optionally methanol, to which water is added prior to catalytic transformation in a reformer for providing it as hydrogen fuel to the fuel cell.

[0031] As an example, in the reformer, the mix of methanol CH.sub.3OH and water H.sub.2O is catalytically converted into hydrogen gas H.sub.2. Simplified, the reactions in the process of methanol steam reaction include decomposition of methanol into carbon monoxide and hydrogen (CH.sub.3OH->2H.sub.2+CO), followed by the water-gas shift reaction (CO+H.sub.2O->CO.sub.2+H.sub.2). The mix of H.sub.2 and CO.sub.2 is then supplied as so-called syngas to the anode side of the fuel cell 3, typically fuel cell stack.

[0032] Air from the environment is sucked in and supplied at increased pressure, typically by using a compressor, to the cathode side of the fuel cell 3 in order to provide the necessary oxygen for the reaction with the hydrogen to produce water, after hydrogen ions H+ have passed the membrane from the anode side to the cathode side.

[0033] The exhaust gases from the fuel cell 3 leave the system through the exhaust 6 of the vehicle 1, for example as illustrated at the very rear of the vehicle 1. Together with the N.sub.2 and some of the O.sub.2 from the air, which has passed through the cathode side of the fuel cell system 4, the produced water vapor is released through the exhaust system. Optionally, the exhaust gas from the fuel cell is mixed with gas from the reformer. For example, the mix is then inserted into a condenser for condensation of the vapor

[0034] As for high temperature fuel cells, the vapor has a temperature far above 100° C., optionally even up to 220° C., the vapor contains a large portion of thermal energy, which potentially causes a risk for a human standing close behind the exhaust pipe 6 end at the rear of the vehicle 1.

[0035] In order to collect drops of water, a wire mesh 7 is provided in the flow path for the exhaust gas from the fuel cell 3, advantageously after a condenser. The wire mesh assists in the separation of water and provides drops 8 that drip out of the exhaust pipe 6 of the vehicle 1.

[0036] Potentially, a heat exchanger 9 is provided as an air cooler, by which the water vapor is cooled and the water more efficiently demisted by the wire mesh 7 prior to release through the outlet 6′ of the exhaust pipe 6. Advantageously, the water vapor is cooled below its dew point, which increases the efficiency of the drop formation by the wire mesh 7.

[0037] The heat exchanger 9 is optionally flow connected with a radiator cooler heat exchanger 10, for example at the front of the vehicle, which is a common location for such general cooler heat exchanger 10.

REFERENCE NUMBERS

[0038] 1 vehicle [0039] 2 ground [0040] 3 fuel cell [0041] 4 fuel cell system [0042] 5 tank [0043] 6 exhaust pipe of vehicle [0044] 6′ outlet of exhaust pipe [0045] 7 wire mesh [0046] 8 drops dripping out of exhaust 6 [0047] 9 cooler [0048] 10 radiator heat exchange cooler of vehicle