Gas and liquid contact apparatus – Contact devices – Porous sheet
Reexamination Certificate
2001-01-19
2004-06-29
Bushey, Scott (Department: 1724)
Gas and liquid contact apparatus
Contact devices
Porous sheet
C095S052000, C096S008000
Reexamination Certificate
active
06755399
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a humidifier, a fuel cell system utilizing the same and a humidification process, and particularly to a humidifier utilizing a hollow fiber membrane, a fuel cell system utilizing the same and a humidification process.
BACKGROUND ARTS
Fuel cell systems, especially solid polymer fuel cell systems are widely known as a power source for electric vehicles. In such fuel cell systems, a humidifier is used to moisture-exchange off gas, viz. moist gas discharged from a fuel cell, between its moisture and air as a dry gas, and to generate humidified air or humidified gas. Preferably, a humidifier used with such fuel cell systems is of a lower power consumption type, and is required compactness with less attachment space. For this reason, among many other humidifiers, such as a supersonic humidifier, a steam humidifier, a vaporizing humidifier and a nozzle injection type humidifier, a humidifier utilizing water permeable membranes, especially hollow fiber membranes is commonly used with a fuel cell.
A conventional humidifier utilizing hollow fiber membranes is disclosed in Japanese Laid-open Patent Publication No. HEI-7-71795. As shown in
FIG. 14
, a humidifier
300
comprises a housing
300
, on which is provided a first inlet
302
for introducing dry air and a first outlet
303
for discharging the dry air (humidified dry air). A bundle of hollow fiber membranes
304
consisting of a number of for example 5000 hollow fiber membranes is accommodated within the housing
301
.
At both ends of the housing
301
, fastening members
305
,
305
′ are provided for fixing the ends of the bundle
304
while leaving them open. Outside of the fastening member
305
is provided a second inlet
306
for introducing moist air or moist gas, and a second outlet
307
is provided outside of the fastening member
305
′ for discharging the moist air, moisture of which is separated and removed at the bundle of hollow fiber membranes
304
. The fastening members
305
,
305
′ are covered with a first head cover
308
and a second head cover
309
, respectively. And the second inlet
306
is formed on the first head cover
308
, while the second outlet
307
is formed on the second head cover
309
.
In the aforementioned humidifier
300
utilizing hollow fiber membranes, the moist air introduced from the second inlet
306
passes through the hollow fiber membranes forming the bundle of hollow fiber membranes
304
, and the moisture within the moist air is separated by capillary action of the hollow fiber membranes. The separated moisture moves outward of the hollow fiber membrane through a capillary tube of the membrane. The moisture-removed air is discharged from the second outlet
307
.
Meanwhile, dry air is supplied from the first inlet
302
. The dry air from the first inlet
302
flows outside of the hollow fiber membranes forming the bundle of hollow fiber membranes. Because the moisture separated from the moist air has moved outside of the hollow fiber membranes, the moisture humidifies the dry air. The humidified dry air is then discharged from the first outlet
303
.
However, in the conventional humidifier
300
shown in
FIG. 14
, the first air inlet
302
which introduces the dry air is formed on the housing
301
at the side near the center of the lengthwise direction thereof. For this reason, as shown in the black arrow of
FIG. 14
, the dry air flowing outside of the hollow fiber membranes in the bundle
304
of the hollow fiber membrane stored within the housing
301
flows the central portion in the lengthwise direction within the housing
301
. Consequently, the areas S residing near the ends of the bundle
304
of the hollow fiber membranes do not contribute to the exchange of water in a sufficient manner and, thus there is a problem that the ratio of moisture recovery at such portions unduly low in relative to the permeable water within the hollow fiber membranes.
SUMMARY OF THE INVENTION
The object of the present invention is to make it possible to water exchange in a sufficient manner even at the portions near the ends of the hollow fiber membranes of the bundle of the hollow fiber membranes stored within the housing to thereby improve the ratio of moisture recovery of the humidifier.
According to the present invention which can attain these and other objects, there is provided a humidifier having a plurality of water-permeable hollow fiber membranes placed along the lengthwise direction of a housing accommodated within the housing in which gases each having a different moisture content flow inside and outside said hollow fiber membranes to carry out moisture exchange whereby the dry air having a low moisture content is humidified, said humidifier comprising: a bypass channel, in which the gas flowing outside the hollow fiber membrane, formed on an approximately central portion of the cross-lengthwise direction of said housing along the lengthwise direction of said housing, said bypass channel having a diameter larger than that of said hollow fiber membrane, and an inlet which introduces the gas flowing outside the hollow fiber membrane into the housing and an outlet which discharges the gas flowing outside the hollow fiber membrane formed on said bypass channel.
The humidifier of the present invention has a bypass channel formed on an approximately central portion of the cross-lengthwise direction of said housing along the lengthwise direction of said housing. Since the bypass channel has a diameter larger than that of said hollow fiber membrane, the gas flowing outside the hollow fiber membrane is introduced into the bypass channel. By being passed through the bypass channel, the gas flowing outside the hollow fiber membrane can be transferred to every areas of the housing. Consequently, since the gas can be supplied over the entire area of the bundle of the hollow fiber membranes, the moisture exchange can be effectively carried out even at an end of the housing, enhancing the moisture recovery.
The term “an approximately central portion of the cross-lengthwise direction of the housing” used herein does not have a meaning of being completely accorded with the center of the cross-lengthwise direction of the housing (the center of the axis), but means to encompass the portion slightly out of the center. Furthermore, it is possible for the formation of the bypass channel if the circumference of the bypass channel is surrounded by the hollow fiber membranes.
In a preferred embodiment of the humidifier according to the present invention, a plurality of the outlets which discharge the gas flowing outside the hollow fiber membrane are formed on said bypass channel at several distance.
According to this embodiment, a plurality of the outlets which discharge the gas flowing outside the hollow fiber membrane are formed on said bypass channel at several distance.
In this embodiment, since a plurality of the outlets which discharge the gas flowing outside the hollow fiber membrane are formed on said bypass channel at several distance, the gas flowing outside the hollow fiber membrane can be discharged in the lengthwise direction in a substantial uniform manner. For this reason, the gas flowing outside the hollow fiber membrane can be supplied to substantially the entire areas of the housing. Accordingly, the moisture exchange can be carried out with higher efficiency.
According to this embodiment, an inlet port for the introduction of the gas flowing outside the hollow fiber membrane into the housing and an outlet port which discharges the gas flowing outside the hollow fiber membrane are formed on the housing, and said inlet port and said outlet port are placed opposite each other beyond the bypass channel.
In this embodiment, an inlet port for the introduction of the gas flowing outside the hollow fiber membrane into the housing and an outlet port which discharges the gas flowing outside the hollow fiber membrane are formed opposite each other beyond the bypass channel. For this reason, the gas flowing outside the holl
Katagiri Toshikatsu
Kusano Yoshio
Shimanuki Hiroshi
Suzuki Motohiro
Arent & Fox PLLC
Bushey Scott
Honda Giken Kogyo Kabushiki Kaisha
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