Humidifier

Details Humidifier Humidifier

2001-01-19

2003-11-25

Gulakowski, Randy (Department: 1746)

Chemistry: electrical current producing apparatus, product, and

With pressure equalizing means for liquid immersion operation

C095S044000, C096S008000

Reexamination Certificate

active

06653012

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. 23
, a humidifier
300
comprises a housing
301
, 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. 23
, 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. 23
, 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 first 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.
The second object of the present invention is to provide a humidifier which can improve the recovery of water utilizing a turbulent flow when the dry air flows outside a bundle of hollow fiber membranes composed of a plurality of water-permeable hollow fiber membranes accommodated within the housing of the hollow fiber membrane module.
The third object of the present invention is to provide a humidifier suitably used for the humidification of the fuel cell, which can improve the water-permeability from the moist gas to the dry gas.
(First Aspect)
According to the first of 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 gas inlet which introduce the gas flowing outside the hollow fiber membranes within the housing formed on an end of the lengthwise direction of the housing.
According to the first aspect of the present invention, a gas inlet which introduce the gas flowing outside the hollow fiber membranes within the housing is formed on an end of the lengthwise direction of the housing. For this reason, the gas flowing outside of the hollow fiber membranes can be spread over the ends of the housing and, thus the water exchange can be carried out in a sufficient manner, even at the ends of the bundle of the hollow fiber membranes.
In the humidifier according to the first aspect, an injector which injects the gas flowing outside the hollow fiber membranes may be placed directionally to an end of the lengthwise direction of the housing.
In this embodiment, the gas flowing outside the hollow fiber membranes is injected toward the end of the housing. For this reason, the gas flowing outside of the hollow fiber membranes can be spread over the ends of the housing. Consequently, the water exchange can be carried out in much more sufficient manner, not only at the center but also at the ends of the bundle of the hollow fiber membranes, improving the recovery of water.
In the humidifier according to the first aspect, an injector which injects the gas flowing outside the hollow fiber membranes may also be placed toward the center of the lengthwise direction of the housing, alternative to the direction of the end of the housing.
In this embodiment, the gas flowing outside the hollow fiber membranes is injected from the end(s) of the lengthwise direction of the housing toward the center of the housing. Due to the current of the gas flowing outside the hollow fiber membranes, the gas flowing outside the hollow fiber membranes can be supplied over the whole areas of the housing. As a result, the water can be effectively recovered from the entire areas of bundle of the hollow fiber membranes including the ends of the housing, improving the recovery of the water.
In the humidifier according to the first aspect where the injector is provided, a generator which generate a circular flow of the gas flowing outside the hollow fiber membranes injected from the injector may be provided.
According to this embodiment, the gas flowing outside the hollow fiber membranes is injected as a circular flow. This makes the gas flowing outside the hollow fiber membranes turbulent flow. Due to the turbulent flow of the gas flowing outside the hollow fiber membranes, the gas flowing outside the hollow fiber membranes can be spread over the entire area of the housing from one end to another end of the housing in much more effective manner. What is

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