Apparatus for generating water vapor with heat-retaining medium and fuel cell system having the apparatus

1. A water-vapor generating apparatus comprises:

a chamber body having an inner space defined therein;

a partitioning member disposed within the inner space of the chamber body and configured to divide the inner space into a water-vapor discharge space and a heating space;

a tubular pipe having a first opened end connected to an external water-supply apparatus and a second opened end disposed in the water-vapor discharge space, wherein the tubular pipe extends through the heating space;

a heater configured to supply thermal energy to the heating space; and

a heat-retaining medium disposed in the water-vapor discharge space, the heat retaining medium comprising a material having a specific heat greater than that of the chamber body and the partitioning member and configured to absorb thermal energy and convert liquid water into water-vapor with the absorbed thermal energy,

wherein the chamber body has a water-vapor outlet connecting the water-vapor discharge space to a fuel reforming apparatus.

2. The apparatus of claim 1 , wherein the heater comprises a hot-gas supply apparatus configured to supply hot-gas to the heating space,

wherein the chamber comprises a gas inlet through which the hot-gas is injected from the hot-gas supply apparatus into the heating space; and a gas outlet through which the hot-gas in the heating space is discharged into an outside of the heating space.

3. The apparatus of claim 1 , wherein the heater comprises an electro-thermal heater disposed on a side wall of the chamber body defining the heating space therein.

4. The apparatus of claim 1 , wherein the heat-retaining medium comprises a plurality of beads or a medium having a foam or mesh structure.

5. The apparatus of claim 1 , wherein the water-vapor discharge space comprises a first sub-space to which the water-vapor outlet is connected and a second sub-space disposed below the first sub-space, the second sub-space receiving the heat-retaining medium, wherein a top portion of the second subspace is in communication with the first sub-space and lateral and bottom portions of the second sub-space are surrounded by the heating space.

6. The apparatus of claim 5 , wherein the partitioning member comprises:

a first partitioning sub-member coupled to the chamber body and configured to partition between the first sub-space and the heating space, the first partitioning sub-member having an opening formed therethrough; and

a second partitioning sub-member extending downward from the opening of the first partitioning sub-member, the second partitioning sub-member being configured to define the second sub-space therein, and to partition between the second sub-space and the heating space.

7. The apparatus of claim 6 , wherein an upper surface of the first partitioning sub-member extends to be tilted downwards toward the second space so that liquid water dropped on the upper surface of the first partitioning sub-member moves toward the second space via a gravity.

8. The apparatus of claim 5 , wherein the water-vapor generating apparatus further comprises a liquid-water detector disposed within the second space to sense liquid water present in the second space.

9. The apparatus of claim 8 , wherein the liquid-water detector comprises a temperature sensor or a liquid sensor disposed in the second space.

10. The apparatus of claim 5 , wherein the tubular pipe disposed in the heating space extends in a form of a coil surrounding the second space.

11. A fuel cell system comprising:

a water-vapor generating apparatus configured to convert liquid water supplied from a water-supply apparatus into water-vapor;

a fuel reforming apparatus configured to generate a fuel gas containing hydrogen by reacting hydrocarbon fuel with the water-vapor supplied from the water-vapor generating apparatus; and

a fuel cell stack configured to generate electricity using the fuel gas supplied from the fuel reforming apparatus and air supplied from an external air supply apparatus, wherein the water-vapor generating apparatus comprises:

a chamber body having an inner space defined therein;

a partitioning member disposed within the inner space of the chamber body and configured to divide the inner space into a water-vapor discharge space and a heating space;

a tubular pipe having a first opened end connected to an external water-supply apparatus and a second opened end disposed in the water-vapor discharge space, wherein the tubular pipe extends through the heating space;

a heater configured to supply thermal energy to the heating space; and

a heat-retaining medium disposed in the water-vapor discharge space, the heat retaining medium comprising a material having a specific heat greater than that of the chamber body and the partitioning member and configured to absorb thermal energy and convert liquid water into water-vapor with the absorbed thermal energy,

wherein the chamber body has a water-vapor outlet connecting the water-vapor discharge space to the fuel reforming apparatus.

12. The system of claim 11 , wherein the heater comprises a combustor configured to combust gas discharged from the fuel cell stack and to supply the combusted gas to the heating space.

13. The system of claim 11 , wherein the water-vapor generating apparatus further comprises a liquid-water detector disposed within the water-vapor discharge space to sense liquid water present in the water-vapor discharge space.