WO2013061170A1

WO2013061170A1 - An air humidification system of a fuel cell stack and method thereof

Info

Publication number: WO2013061170A1
Application number: PCT/IB2012/051441
Authority: WO
Inventors: Raja MUNUSAMY; Bhut Bhaveshkumar DHIRAJLAL; Yogesha Sankenhalli ANNEGOWDA
Original assignee: Tata Motors Limited
Priority date: 2011-10-24
Filing date: 2012-03-27
Publication date: 2013-05-02

Abstract

The present disclosure relates to an air humidification system of a fuel cell stack. The system comprises, at least one heat exchanger having an air inlet manifold and air outlet manifold, wherein said air inlet manifold and said air outlet manifold are fluidly connected for supplying the air, and a coolant inlet manifold and coolant outlet manifold, wherein said coolant inlet manifold and said coolant outlet manifold are fluidly connected to supply the coolant, characterized in that, the air inlet manifold comprises: a water dispensing tube placed concentrically inside the manifold, wherein said water dispensing tube consists of plurality of perforations on its circumference for sprinkling the water; a slot tube placed concentrically in between the water dispensing tube and the manifold and a porous matrix sheet covered around the slotted tube for humidifying the air.

Description

"AN AIR HUMIDIFICATION SYSTEM OF A FUEL CELL STACK AND

METHOD THEREOF"

TECHINCAL FIELD

Embodiments of the present disclosure relates to a humidification system, more particularly embodiments relates to the air humidification system of a fuel cell stack.

BACKGROUND OF DISCLOSURE

Fuel cell is defined as an electrochemical cell that directly converts chemical energy of a fuel into electrical energy. Unlike a conventional battery, the fuel cell can continuously produce electricity as long as the fuel and air are supplied thereto. The fuel cell system generally comprises a fuel cell stack for generating electricity, a fuel supply system for supplying fuel (hydrogen) to the fuel cell stack, an air supply system for supplying oxygen in air, which is an oxidizing agent required for en electrochemical reaction, to the fuel cell stack, and a heat and water management system for removing reaction heat of the fuel cell stack to the outside of the fuel cell system and controlling the operation temperature of the fuel cell stack. The fuel cell system having generates electricity by the electrochemical reaction of hydrogen as fuel and oxygen in the air and exhausts heat and water as reaction by-products.

The fuel cell system requires humid air to facilitate the chemical reaction. The reactants in the fuel cell are humidified to keep polymer membrane wet and saturated with the water for sustained ionic conductivity.

The conventional humidification system comprises a dosing pump for supplying water to a nozzle placed inside the air inlet port. The nozzle sprinkles the water onto the air flowing through the air inlet port for humidification. Since, the water is sprinkled onto the air there will be no proper mixture of air and water, hence the proper humidification will not be possible with the conventional system. Further, there will be a pressure drop in the conventional humidification system because the water is directly sprinkled on the air, which will not be feasible for fuel cell stack working. In light of forgoing discussion, it is necessary to develop a system and method for an air humidification in fuel cell system to overcome the limitations stated above.

STATEMENT OF THE DISCLOSURE Accordingly, the present disclosure provides an air humidification system of a fuel cell stack comprising: at least one heat exchanger for humidifying the air, comprising: an air inlet manifold at a bottom end of a first side of the heat exchanger and air outlet manifold at a top end of a second side of the heat exchanger, wherein said air inlet manifold and said air outlet manifold are fluidly connected; and a coolant inlet manifold at the bottom end of the second side of the heat exchanger and coolant outlet manifold at the top end of the first side of the heat exchanger, wherein said coolant inlet manifold and said coolant outlet manifold are fluidly connected, characterized in that, the air inlet manifold comprises: a water dispensing tube placed concentrically inside the manifold, wherein said water dispensing tube consists of plurality of perforations on its circumference for sprinkling the water; a slot tube placed concentrically in between the water dispensing tube and the manifold; and a porous matrix sheet covered around the slotted tube for humidifying the air, and also provides for a method of humidifying an air by an air humidification system of a fuel cell stack, said method comprising acts of: supplying water through a water dispensing tube which sprinkles the water on to a porous matrix; supplying the air though an air inlet manifold around the porous matrix for humidifying the air; and passing the humidified air to a heat exchanger to equilibrate with a coolant supplied through a coolant inlet manifold.

SUMMARY OF THE DISCLOSURE

The shortcomings of the prior art are overcome and additional advantages are provided through the provision of a system and method as claimed in the present disclosure.

Additional features and advantages are realized through the techniques of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered a part of the claimed disclosure. One embodiment of the present disclosure provides an air humidification system of a fuel cell stack. The system comprises, at least one heat exchanger for humidifying the air, having an air inlet manifold at a bottom end of a first side of the heat exchanger and air outlet manifold at a top end of a second side of the heat exchanger, wherein said air inlet manifold and said air outlet manifold are fiuidly connected. And a coolant inlet manifold at the bottom end of the second side of the heat exchanger and coolant outlet manifold at the top end of the first side of the heat exchanger, wherein said coolant inlet manifold and said coolant outlet manifold are fiuidly connected. Characterized in that, the air inlet manifold comprises: a water dispensing tube placed concentrically inside the manifold, wherein said water dispensing tube consists of plurality of perforations on its circumference for sprinkling the water; a slot tube placed concentrically in between the water dispensing tube and the manifold; and a porous matrix sheet covered around the slotted tube for humidifying the air. In one embodiment of the present disclosure, the heat exchanger is plate type heat exchanger.

In one embodiment of the present disclosure, the number of heat exchangers are varied depending on the load requirement of the fuel cell stack.

In one embodiment of the present disclosure, a heater is provided in the heat exchanger for heating the coolant if the temperature of the coolant is below the predetermined limit.

In one embodiment of the present disclosure, a water drain port is provided in the air inlet manifold for removing the excess water in the air inlet manifold.

In one embodiment of the present disclosure, the porous matrix sheet is selected from at least one of glass fiber matrix, and polypropylene, polytetrafluro ethylene. In one embodiment of the present disclosure, at least one wire mesh covered around the porous matrix to hold the matrix firmly around the slotted tube. Another embodiment of the present disclosure relates to a method of humidifying an air by an air humidification system of a fuel cell stack. A said method fallow the steps of water is supplied through a water dispensing tube which sprinkles the water on to a porous matrix. Then the air is supplied though an air inlet manifold around the porous matrix for humidifying the air. And the humidified air is passed to a heat exchanger to equilibrate with a coolant supplied through a coolant inlet manifold.

The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.

OBJECTIVES OF THE DISCLOSURE One object of the present disclosure is to provide an air humidification system of a fuel cell stack which humidifies the air with no pressure drop across the air inlet manifold.

One object of the present disclosure is to provide an air humidification system of a fuel cell stack which has a glass fiber matrix wrapped around the water dispensing tube for better humidification of air.

One object of the present disclosure is to provide an air humidification system of a fuel cell stack which has a plate type heat exchanger which acts as heat sink or heat source depending on inlet condition of air.

BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES

The novel features and characteristic of the disclosure are set forth in the appended claims. The disclosure itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying figures. One or more embodiments are now described, by way of example only, with reference to the accompanying figures wherein like reference numerals represent like elements and in which: FIG. 1 illustrates a block diagram of fuel cell system.

FIG. 2 illustrates a perspective view of an air humidification system of the present disclosure.

FIG. 3 illustrates a cut section view of an air inlet manifold of the air humidification system of the present disclosure. FIG. 4 illustrates a line diagram of an air humidification system of a present disclosure.

The figures depict embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.

DETAILED DESCRIPTION

The foregoing has broadly outlined the features and technical advantages of the present disclosure in order that the detailed description of the disclosure that follows may be better understood. Additional features and advantages of the disclosure will be described hereinafter which form the subject of the claims of the disclosure. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the disclosure as set forth in the appended claims. The novel features which are believed to be characteristic of the disclosure, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present disclosure. To overcome the drawbacks mentioned in the background, a system and method for an air humidification in fuel cell system is discussed in the present disclosure. The system comprises main parts such as plurality of heat exchangers having an air inlet and outlet manifolds and coolant inlet and outlet manifolds for humidifying the air.

FIG. 1 illustrates a block diagram of the fuel cell system as one embodiment. The fuel cell system consist of major components such as air compressor (401), dosing pump (402), water dispensing system (103), plate type heat exchanger (201), controller (102) and the stack (101).

Air Compressor (401): Supplies required air flow to the system based on demand.

Humidifier System (200): Humidifies the air and takes required heat for humidification from the hot fluid coming out of the stack (101). Heats released by air compressor due to inefficiency in the compression process and fuel cell stack is used for air humidification and conditioning.

Heater (403): Heater will heat the coolant flowing from the fuel cell stack (101) to the heat exchanger (201) if the temperature of the coolant is below 40 Deg C.

Water Dispensing System (103): Water Dispensing System (103) includes air inlet manifold (202), glass fibre matrix (202c), and out-ports (203) for air, excess water port (202d). The water dispensing tube of the water dispensing system sprays the water in mist form into humidifier system (200) by means of pressurised water through Dosing pump (402).

Glass fibre matrix (202c): The Glass fiber matrix (202c) puts water vapor particles in the air so that air humidity gradually increases. Air passing through porous glass fibre matrix will be mix with water vapour content of the water; hence the uniform mixture of air and water is achieved. Fuel Cell Stack (101): Fuel Cell Stack (101) is a electrochemical device, which generates the Power and heat. For optimum performance and extended durability of Stack it is required to maintain its temperature between 65°C to 75°C. Temperature Sensor: It senses the temperature of the fluid.

Relative Humidity Sensor: It senses the relative humidity of the fluid.

Radiator (104): Removes the excess heat from the system by means of throwing the heat into atmosphere through fans. Heat dissipation of radiator (104) depends on no of fans switched on and flow rate of coolant running into system.

Coolant Pump (105): Circulate the coolant into system with variable speed drive to vary the flow rate of the coolant.

Controller (102): Electronics Control Unit (ECU) takes the input from sensors (in this case temperature and humidity sensor) and generates the control signals for radiator fans, Coolant pump, and Dosing Pump. Water Tank (106): The water tank (106) collects and stores the excess water coming out of water drain port and the fuel cell stack.

The air compressor (401) blows the required quantity of pressurized air to the air humidifier (200) with required pressure. The air humidifier (200) gets the air from compressor and vaporized water from water dispensing system (103) and produces humid air. The humid air is passed to the cathode compartment of fuel cell stack (101). A dosing pump (402) supplies water to the water dispensing system (103) for humidifying the air. Said dosing pump (102) is interfaced with the controller (102) for controlling the flow of water through the dosing pump based on the load demand of the fuel cell.

FIG. 2 is an exemplary embodiment which illustrates a perspective view of an air humidification system (200) of the present disclosure. The system comprises plurality of plate type heat exchangers (201) placed in series. The plate type heat exchanger (201) is a type of heat exchanger that uses metal plates to transfer heat between two fluids. This has a major advantage over a conventional heat exchanger in that the fluids are exposed to a much larger surface area because the fluids spread out over the plates. This facilitates the transfer of heat, and greatly increases the speed of the temperature change. An air inlet manifold (202) connected at bottom end (201a) of a first side (201b) of the heat exchangers (201) for supplying the air to the air humidification system (200). An air outlet manifold (203) connected at top end (201c) of a second side (20 Id) of the heat exchangers (200) for supplying the humidified air to the fuel cell stack (101). The air inlet manifold (202) and air outlet manifold (203) are fluidly connected for supplying air to the fuel cell stack (101). A coolant inlet manifold (204) connected at the bottom end (20 le) of the second side (20 Id) of the heat exchanger (201) for supplying the coolant emerging out of the stack to the heat exchanger (201). And a coolant outlet manifold (205) provided at the top end (20 If) of the first side (201b) of the heat exchanger (201) for passing the coolant back to the fuel cell stack (101). The said coolant inlet manifold (204) and said coolant outlet manifold (205) are fluidly connected for circulating the coolant inside the heat exchanger (201) to facilitate heat exchange between the humidified air and the coolant. Further, the said coolant inlet manifold (204) and coolant outlet manifold (205) are connected to the hydrogen humidifier.

FIG. 3 is an exemplary embodiment which illustrates a cut section view of an air inlet manifold of the air humidification system of the present disclosure. The air inlet manifold (202) comprises an air inlet side which is connected to an out let of an air compressor

(401) as shown in FIG. 3 for supplying compressed air to the air humidification system (200). A water dispensing tube (202a) having a diameter approximately three times less than the air inlet manifold (202) is placed concentrically inside the air inlet manifold (202). The water dispensing tube (202a) is consists of plurality of perforations on its top circumference for sprinkling the water. The said tube is connected to a dosing pump

(402) as shown in FIG. 3 for supplying the water for air humidification. The water and air are supplied in opposite directions in order to get a uniform mixture of water and air for proper humidification of the air. A slot tube (202b) is placed concentrically around the water dispensing tube inside the manifold (202). Said slot tube (202b) consists of plurality of concentric ribs throughout its length. And a porous matrix sheet (202c) wrapped around the slot tube using at least one wire mesh (202d). The porous matrix sheet (202c) absorbs the water sprinkled by the water dispensing tube (202a) and mix the water with the air passing from the air inlet side of the manifold (202) for humidifying the air. In one embodiment, the porous matrix sheet is selected from a group comprising but not limited to glass fiber matrix or any other porous matrix which serve the purpose. In one embodiment, a water drain port (202e) is provided in the air inlet manifold (202) for removing the excess water in the air inlet manifold (202) and the water coming out of the fuel cell stack (101). In one embodiment of the present disclosure, hot air is allowed to interact with wet porous matrix. Matrix with appropriate Porosity is chosen so that there is no pressure drop across the manifold. Air is cooled and get humidified. Humidified air along with mist of water carried into the plate heat exchanger (201) and allowed to equilibrate with hot fluid emerges out of the fuel cell stack. The plate heat exchanger of the present disclosure, acts either as heat sink or heat sources depending on the input condition of the air.

FIG. 3 is an exemplary embodiment which illustrates a line diagram an air humidification system of the present disclosure. The air is supplied to an air compressor (401) through an air inlet. The air compressor (401) compresses the air which increases the pressure and temperature of the air. The hot air is allowed to pass through the air inlet manifold (202) of the humidification system (200) for humidifying the air to humidify the reactants in the fuel cell to keep polymer membrane of the fuel cell stack (101) wet and saturated with the water for sustained ionic conductivity. The air inlet manifold (202) consists of the water dispensing tube (202a) placed axially for sprinkling the water onto the air passing through the manifold (202) for humidifying the air. The humidified air along with the mist is carried into the plate type heat exchanger (201) and allowed to equilibrate with the hot fluid emerges out of fuel cell stack (101). The humidification system (200) consists of heater (403) for heating the coolant flowing from the fuel cell stack (101) to the heat exchanger (201) when the temperature of the coolant is less than 40 degree Celsius. The air after humidification is passed into the fuel cell system for its operation. Table.l shows the values of load, temperature, pressure and humidity at node points A, B and C as shown in FIG. 3. In one embodiment, for idle operation if the fuel cell system the humidity of air at node C should not fall below 70.

Table.1

For ideal operation of the fuel cell system the humidity of the air at node C should be maintained at predetermined values as shown in the Table.l depending on the load. As the load increases the humidity value decreases. Thus load is inversely proportional to humidity.

Advantages:

The present disclosure provides an air humidification system of a fuel cell stack which humidifies the air with no pressure drop across the air inlet manifold. Hence it improves overall the efficiency of the fuel cell system. The present disclosure provides an air humidification system of a fuel cell stack which has a glass fiber matrix wrapped around the water dispensing tube for better humidification of air. Hence, it improves the humidity of the air. The present disclosure provides an air humidification system of a fuel cell stack which has a plate type heat exchanger which acts as heat sink or heat source depending on inlet condition of air. Hence, uniform temperature of the humidified of the air throughout operation of the fuel cell system. The present disclosure provides an air humidification system of a fuel cell stack which has a heater which heats the coolant flowing from fuel cell stack to the heat exchanger, if the temperature of the coolant is less than 40°C.

Equivalents

With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity.

It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as "open" terms (e.g., the term "including" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "includes" should be interpreted as "includes but is not limited to," etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles "a" or "an" limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an" (e.g., "a" and/or "an" should typically be interpreted to mean "at least one" or "one or more"); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of "two recitations," without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to "at least one of A, B, and C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, and C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to "at least one of A, B, or C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, or C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase "A or B" will be understood to include the possibilities of "A" or "B" or "A and B." While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims. Referral Numerals:

Reference number Description

101 Fuel cell stack

102 Controller

103 Water dispensing system

104 Radiator

105 Coolant pump

106 Water tank

200 Air humidification system

201 Plate type heat exchanger

201a Bottom end of first side of the heat exchanger

201b First side of the heat exchanger

201c Top end of second side of the heat exchanger

201d Second side of the heat exchanger

201e Bottom end of the second side of the heat exchanger

201f Top end of the first side of the heat exchanger

202 Air inlet manifold

202a Water dispensing tube

202b Slot tube

202c Porous matrix sheet

202d Wire mesh

202e Water drain port

203 Air outlet manifold

204 Coolant inlet manifold

205 Coolant outlet manifold 401 Air compressor

402 Dosing pump

403 Heater

Claims

We claim:

1. An air humidification system (200) of a fuel cell stack comprising:

at least one heat exchanger (201) for humidifying the air, comprising: an air inlet manifold (202) at a bottom end (201a) of a first side (201b) of the heat exchanger (201) and air outlet manifold (203) at a top end (201c) of a second side (20 Id) of the heat exchanger (201), wherein said air inlet manifold (202) and said air outlet manifold (203) are fluidly connected; and

a coolant inlet manifold (204) at the bottom end (201 e) of the second side (20 Id) of the heat exchanger (201) and coolant outlet manifold (205) at the top end (20 If) of the first side (201b) of the heat exchanger (201), wherein said coolant inlet manifold (204) and said coolant outlet manifold (205) are fluidly connected,

characterized in that,

the air inlet manifold (202) comprises:

a water dispensing tube (202a) placed concentrically inside the manifold (202), wherein said water dispensing tube (202a) consists of plurality of perforations on its circumference for sprinkling the water;

a slot tube (202b) placed concentrically in between the water dispensing tube (202a) and the manifold (202); and

a porous matrix sheet (202c) covered around the slotted tube (202b) for humidifying the air.

2. The system as claimed in claim 1, wherein the heat exchanger (201) is plate type heat exchanger.

3. The system as claimed in claim 1 , wherein the number of heat exchangers (201) are varied depending on the load requirement of the fuel cell stack.

4. The system as claimed in the claim 1, wherein a heater (403) is provided in the heat exchanger (201) for heating the coolant if the temperature of the coolant is below the predetermined limit.

5. The system as claimed in claim 1, wherein a water drain port (202e) is provided in the air inlet manifold (202) for removing the excess water in the air inlet manifold (202).

6. The system as claimed in claim 1 , wherein the porous matrix sheet (202c) is selected from at least one of glass fiber matrix, and polypropylene, polytetrafluroethylene.

7. The system as claimed in claim 1, wherein at least one wire mesh (202d) covered around the porous matrix (202c) to hold the matrix (202c) firmly around the slotted tube (202b).

8. A method of humidifying an air by an air humidification system (100) of a fuel cell stack, said method comprising acts of:

supplying a water through a water dispensing tube (202a) which sprinkles the water on to a porous matrix (202c);

supplying the air though an air inlet manifold (202) around the porous matrix (202c) for humidifying the air; and

passing the humidified air to a heat exchanger (201) to equilibrate with a coolant supplied through a coolant inlet manifold.

9. A vehicle comprising an air humidification system of a fuel cell stack as claimed in claim 1.

10. An air humidification system of a fuel cell stack and a method of humidifying an air by an air humidification system of a fuel cell stack are substantially as herein above described and as illustrated in accompanying drawings.