Humidifier for a fuel cell

1. A humidifier for a fuel cell, the humidifier comprising:

a body;

first and second humidifying spaces formed inside the body, wherein humidifying membranes through which inflow gas flows to be introduced into a fuel cell stack are installed in the first and second humidifying spaces;

an exhaust gas inlet and an exhaust gas outlet disposed at the body and configured to supply exhaust gas released from the fuel cell stack to the first and second humidifying spaces, the exhaust gas having higher humidity than the inflow gas;

a passing space formed inside the body and directly or indirectly communicated with the second humidifying space and the fuel cell stack, wherein the inflow gas flows into the passing space from the first humidifying space; and

a first valve installed in the passing space to allow the inflow gas introduced into the passing space to flow into the fuel cell stack passing through the second humidifying space or into the fuel cell stack without passing through the second humidifying space, or to allow some of the inflow gas introduced into the passing space to flow into the fuel cell stack passing through the second humidifying space and others of the inflow gas introduced into the fuel cell stack without passing through the second humidifying space,

wherein a flow path, in which the inflow gas introduced into the body flows into the fuel cell stack without passing through the second humidifying space, is configured to be selected by controlling the first valve.

2. The humidifier of claim 1 , wherein the first valve includes a first valve plate hingedly installed in the passing space, and

wherein the first valve plate is movable between a first position where the first valve plate allows the inflow gas introduced into the passing space to flow into the second humidifying space and a second position where the first valve plate allows the inflow gas introduced into the passing space to flow into the fuel cell stack except through the second humidifying space.

3. The humidifier of claim 2 , further comprising:

an elastic member configured to increase air tightness when the first valve plate is located in the first or second position.

4. The humidifier of claim 1 , further comprising:

a first communicating space formed inside the body, wherein the inflow gas not passing through the second humidifying space and/or the inflow gas passing through the second humidifying space flows into the first communicating space,

wherein the body includes a first inflow gas outlet that is open at one side of the body and through which the inflow gases introduced into the first communicating space are released toward the fuel cell stack.

5. The humidifier of claim 4 , wherein a cross-sectional area of the first inflow gas outlet is substantially equal to an entire cross-sectional area of a flow passage through which the inflow gas flows from the passing space into the second humidifying space.

6. The humidifier of claim 1 , wherein the first and second humidifying spaces are arranged parallel to each other with a partition wall therebetween such that the inflow gas flows in a first direction in the first humidifying space and flows in an opposite direction to the first direction in the second humidifying space.

7. The humidifier of claim 6 , wherein:

the exhaust gas inlet has one end communicated with the outside of the body and an opposite end communicated with the first and second humidifying spaces to cause the exhaust gas to flow into the body; and

the exhaust gas outlet has one end communicated with the first and second humidifying spaces and an opposite end communicated with the outside of the body to release the exhaust gas out of the body.

8. The humidifier of claim 1 , wherein the exhaust gas supply inlet and the exhaust gas outlet are configured to supply more exhaust gas to the second humidifying space than the first humidifying space.

9. The humidifier of claim 1 , wherein the humidifying membrane installed in the second humidifying space has a higher moisture permeability than the humidifying membrane installed in the first humidifying space.

10. The humidifier of claim 1 , wherein the humidifying membrane installed in the first humidifying space includes a plurality of hollow fiber membranes,

wherein the humidifying membrane installed in the second humidifying space includes a plurality of hollow fiber membranes, and

wherein the number of hollow fiber membranes installed in the first humidifying space is smaller than the number of hollow fiber membranes installed in the second humidifying space.

11. The humidifier of claim 1 , further comprising:

a second communicating space formed inside the body to guide the inflow gas introduced into the body toward the passing space without passing through the first humidifying space; and

a second valve configured to allow the inflow gas introduced into the body to flow into the first humidifying space or the second humidifying space or allow some of the inflow gas introduced into the body to flow into the first humidifying space and others of the inflow gas introduced into the body to flow into the second humidifying space.

12. The humidifier of claim 11 , wherein the first valve is positioned to cause all of the inflow gas introduced into the passing space to flow into the fuel cell stack without passing through the second humidifying space when the second valve is positioned to cause all of the inflow gas introduced into the body to flow into the second communicating space.