Patent Publication Number: US-2010119897-A1

Title: Hydrogen fuel cell systems

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This Application claims priority of Taiwan Patent Application No. 097143026, filed on Nov. 7, 2008, the entirety of which is incorporated by reference herein. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to hydrogen fuel cell systems, and more particularly to hydrogen fuel cell systems with enhanced operational efficiency. 
     2. Description of the Related Art 
     Generally, in a fuel cell employing hydrogen (H 2 ) as fuel, the equation for a redox reaction at a cathode side and an anode side is as follows. 
     At the anode side: H 2 →2H + +2e − ; 
     At the cathode side: 1/2O 2 +2H + +2e − →H 2 O. 
     Specifically, in the aforementioned fuel cell, hydrogen is carried by water steam to the anode side for reaction. Here, the water steam serves as a carrier and provides functions of enhancing conductivity and reducing reaction temperature. Accordingly, a hydrogen fuel cell is commonly used with a humidifier. 
     Referring to  FIG. 1 , a conventional humidifier  1  for a hydrogen fuel cell comprises a reservoir  11 , an input pipe  12 , an output pipe  13 , a heater  14 , a temperature controller  15 , a thermal insulation member  16 , a thermometer  17 , a level monitor  18 , and a hygrometer  19 . 
     The reservoir  11  receives water. 
     The input pipe  12  connects the reservoir  11  to a hydrogen supply source  2 . 
     The output pipe  13  connects the reservoir  11  to a hydrogen fuel cell module  3 . 
     The heater  14  is disposed in the reservoir  11 . 
     The temperature controller  15  is electrically connected to the heater  14 , controlling heating operation thereof. 
     The thermal insulation member  16  covers the output pipe  13 . 
     The thermometer  17 , level monitor  18 , and hygrometer  19  are disposed in the reservoir  11 , respectively detecting the water temperature, water level, and humidity in the reservoir  11 . 
     When the humidifier  1  operates, the heater  14  heats the water in the reservoir  11  to a predetermined temperature, vaporizing the water into high-temperature steam. Hydrogen is then transported into the reservoir  11  from the hydrogen supply source  2  via the input pipe  12 , mixing with the high-temperature steam. The mixed high-temperature steam and hydrogen are then transported to the hydrogen fuel cell module  3  via the output pipe  13 , performing a redox reaction. Here, the thermal insulation member  16  covering the output pipe  13  can prevent condensation of the high-temperature steam during transportation thereof. 
     Following are some drawbacks of the conventional humidifier  1 . Because the humidifier  1  must be equipped with the heater  14 , temperature controller  15 , thermal insulation member  16 , thermometer  17 , level monitor  18 , and hygrometer  19 , control thereof is complicated and overall manufacturing costs thereof is high. Moreover, when the humidifier  1  begins to operate, the hydrogen must be transported into the reservoir  11  only after the water temperature in the reservoir  11  reaches the predetermined temperature, consuming additional energy requiring additional time, and further delaying operation of the hydrogen fuel cell module  3 . 
     BRIEF SUMMARY OF THE INVENTION 
     A detailed description is given in the following embodiments with reference to the accompanying drawings. 
     An exemplary embodiment of the invention provides a hydrogen fuel cell system comprising a hydrogen fuel cell module, a gas/water distributor, a hydrogen input pipe, a reservoir, a water input pipe, a pump, a gas/water confluent device, and an output pipe. The gas/water distributor connects to the hydrogen fuel cell module. The hydrogen input pipe connects to the gas/water distributor, inputting hydrogen thereinto. The reservoir receives water. The water input pipe connects the gas/water distributor to the reservoir. The pump is connected to the water input pipe, transporting the water from the reservoir to the gas/water distributor. The gas/water confluent device connects to the hydrogen fuel cell module. The hydrogen fuel cell module is disposed between the gas/water distributor and the gas/water confluent device. The output pipe connects the gas/water confluent device to the reservoir. 
     The hydrogen fuel cell system further comprises an electromagnetic valve connected to the output pipe. 
     The hydrogen fuel cell system further comprises a controller electrically connected to the pump and electromagnetic valve, controlling operation thereof. 
     The hydrogen fuel cell system further comprises a check valve connected to the water input pipe and disposed between the reservoir and the pump. 
     The reservoir comprises an exhaust, discharging gas to the exterior of the reservoir. 
     The exhaust comprises a gas/liquid separation film. 
     Another exemplary embodiment of the invention provides a hydrogen fuel cell system comprising a hydrogen fuel cell module, a gas/water distributor, a hydrogen input pipe, a reservoir, a booster, a water input pipe, a gas/water confluent device, and a first output pipe. The gas/water distributor connects to the hydrogen fuel cell module. The hydrogen input pipe connects to the gas/water distributor, inputting hydrogen thereinto. The reservoir receives water. The booster is connected to the gas/water distributor. The water input pipe connects the reservoir to the booster, inputting the water from the reservoir into the booster and gas/water distributor. The gas/water confluent device connects to the hydrogen fuel cell module. The hydrogen fuel cell module is disposed between the gas/water distributor and the gas/water confluent device. The first output pipe connects the gas/water confluent device to the reservoir. 
     The hydrogen fuel cell system further comprises a second output pipe and an electromagnetic valve. The second output pipe is connected to the first output pipe. The electromagnetic valve is connected to the second output pipe. 
     The hydrogen fuel cell system further comprises a controller electrically connected to the electromagnetic valve and booster, controlling operation thereof. 
     The hydrogen fuel cell system further comprises a first check valve connected to the water input pipe. 
     The hydrogen fuel cell system further comprises a second check valve connected to the first output pipe. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein: 
         FIG. 1  is a schematic plane view of a conventional humidifier for a hydrogen fuel cell; 
         FIG. 2  is a schematic perspective view of a hydrogen fuel cell system of a first embodiment of the invention; and 
         FIG. 3  is a schematic perspective view of a hydrogen fuel cell system of a second embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following description is of the best-contemplated mode of carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims. 
     First Embodiment 
     Referring to  FIG. 2 , a hydrogen fuel cell system  100  comprises a hydrogen fuel cell module  110 , a gas/water distributor  120 , a hydrogen input pipe  130 , a reservoir  140 , a water input pipe  150 , a pump  160 , a check valve  170 , a gas/water confluent device  180 , an output pipe  190 , an electromagnetic valve  195 , and a controller  196 . 
     The gas/water distributor  120  connects to a top portion of the hydrogen fuel cell module  110 . Here, multiple and multi-layered micro-channels (not shown) are provided in the gas/water distributor  120 . 
     The hydrogen input pipe  130  connects a hydrogen supply source (not shown) to the gas/water distributor  120 , inputting hydrogen thereinto. For example, the hydrogen may be input into bottom-layer micro-channels (not shown) of the gas/water distributor  120  via the hydrogen input pipe  130 . 
     The reservoir  140  receives water and comprises an exhaust  141 , discharging gas to the exterior of the reservoir  140 . In this embodiment, the exhaust  141  may be a gas/liquid separation film. 
     The water input pipe  150  connects the gas/water distributor  120  to the reservoir  140 . 
     The pump  160  is connected to the water input pipe  150 , transporting the water from the reservoir  140  to the gas/water distributor  120 . For example, the water may be transported from the reservoir  140  to top-layer micro-channels (not shown) of the gas/water distributor  120  by the pump  160 . 
     The check valve  170  is connected to the water input pipe  150  and is disposed between the reservoir  140  and the pump  160 . Here, by disposition of the check valve  170 , the water can flow from the reservoir  140  to the gas/water distributor  120  and cannot flow from the gas/water distributor  120  to the reservoir  140 . 
     The gas/water confluent device  180  connects to a bottom portion of the hydrogen fuel cell module  110 . Here, the hydrogen fuel cell module  110  is disposed between the gas/water distributor  120  and the gas/water confluent device  180 . 
     The output pipe  190  connects the gas/water confluent device  180  to the reservoir  140 . 
     The electromagnetic valve  195  is connected to the output pipe  190 . 
     The controller  196  is electrically connected to the pump  160  and electromagnetic valve  195 , controlling operation thereof. 
     The following description is directed to operation of the hydrogen fuel cell system  100 . 
     The hydrogen is input into the bottom-layer micro-channels of the gas/water distributor  120  using the hydrogen input pipe  130 . At the same time, the controller  196  drives the pump  160  to operate, transporting the water from the reservoir  140  to the top-layer micro-channels of the gas/water distributor  120  via the water input pipe  150 . Here, the water flowing through the top-layer micro-channels of the gas/water distributor  120  transforms into micro-drops approximating to water steam. The micro-drops approximating to water steam uniformly flow into the bottom-layer micro-channels of the gas/water distributor  120 , uniformly mixing with the hydrogen. The uniformly mixed hydrogen and micro-drops then enter the hydrogen fuel cell module  110 , performing a redox reaction. Specifically, partially unused hydrogen and micro-drops are collected by the gas/water confluent device  180  and further enter the output pipe  190 . When the hydrogen and water accumulates to a specific level in the output pipe  190 , the controller  196  drives the electromagnetic valve  195  to open, enabling the hydrogen and water to flow back into the reservoir  140 . The hydrogen can then be discharged to the exterior of the reservoir  140  through the exhaust  141 . Accordingly, by the controller  196  repeatedly controlling the operation of the pump  160  and electromagnetic valve  195 , the redox reaction can be continuously performed in the hydrogen fuel cell module  110 , outputting electric power. 
     Second Embodiment 
     Referring to  FIG. 3 , a hydrogen fuel cell system  200  comprises a hydrogen fuel cell module  210 , a gas/water distributor  220 , a hydrogen input pipe  230 , a reservoir  240 , a booster  250 , a water input pipe  260 , a first check valve  271 , a gas/water confluent device  280 , a first output pipe  291 , a second check valve  272 , a second output pipe  292 , an electromagnetic valve  295 , and a controller  296 . 
     The gas/water distributor  220  connects to a top portion of the hydrogen fuel cell module  210 . Here, multiple and multi-layered micro-channels (not shown) are provided in the gas/water distributor  220 . 
     The hydrogen input pipe  230  connects a hydrogen supply source (not shown) to the gas/water distributor  220 , inputting hydrogen thereinto. For example, the hydrogen may be input into bottom-layer micro-channels (not shown) of the gas/water distributor  220  via the hydrogen input pipe  230 . 
     The reservoir  240  receives water. 
     The booster  250  is connected to a top portion of the gas/water distributor  220 . 
     The water input pipe  260  connects the reservoir  240  to the booster  250 , inputting the water from the reservoir  240  into the booster  250  and gas/water distributor  220 . For example, the water may be transported to top-layer micro-channels (not shown) of the gas/water distributor  220  via the booster  250 . 
     The first check valve  271  is connected to the water input pipe  260 . Here, by disposition of the first check valve  271 , the water can flow from the reservoir  240  to the booster  250  and cannot reversely flow thereto. 
     The gas/water confluent device  280  connects to a bottom portion of the hydrogen fuel cell module  210 . Here, the hydrogen fuel cell module  280  is disposed between the gas/water distributor  220  and the gas/water confluent device  280 . 
     The first output pipe  291  connects the gas/water confluent device  280  to the reservoir  240 . 
     The second check valve  272  is connected to the first output pipe  291 . Here, by disposition of the second check valve  272 , the water can flow from the gas/water confluent device  280  to the reservoir  240  and cannot reversely flow thereto. 
     The second output pipe  292  is connected to the first output pipe  291 . 
     The electromagnetic valve  295  is connected to the second output pipe  292 . 
     The controller  296  is electrically connected to the electromagnetic valve  295  and booster  250 , controlling operation thereof. 
     The following description is directed to operation of the hydrogen fuel cell system  200 . 
     The controller  296  drives the electromagnetic valve  295  to close. The hydrogen is then input into the bottom-layer micro-channels of the gas/water distributor  220  using the hydrogen input pipe  230 . At the same time, the controller  296  drives the booster  250  to perform a boosting operation, compulsively transporting the water from the reservoir  240  to the top-layer micro-channels of the gas/water distributor  220  via the booster  250 . Here, the water flowing through the top-layer micro-channels of the gas/water distributor  220  transforms into micro-drops approximating to water steam. The micro-drops approximating to water steam uniformly flow into the bottom-layer micro-channels of the gas/water distributor  220 , uniformly mixing with the hydrogen. The uniformly mixed hydrogen and micro-drops then enter the hydrogen fuel cell module  210 , performing a redox reaction. Specifically, partially unused hydrogen and micro-drops are collected by the gas/water confluent device  280  and further enter the first output pipe  291  and second output pipe  292 . Then, the controller  296  drives the electromagnetic valve  295  to open, discharging the hydrogen and water to the exterior of the hydrogen fuel cell system  200  via the second output pipe  292 . Accordingly, by repeatedly operating the booster  250  and electromagnetic valve  295 , the redox reaction can be continuously performed in the hydrogen fuel cell module  210 , outputting electric power. 
     In conclusion, the disclosed hydrogen fuel cell systems provide many advantages. Because heaters, temperature controllers, thermal insulation members, thermometers, level monitors, and hygrometers are not required by the disclosed hydrogen fuel cell systems, overall manufacturing costs of the disclosed hydrogen fuel cell systems are reduced. Moreover, as each of the disclosed hydrogen fuel cell systems uses only a controller to humidify the hydrogen, operation and control thereof are simplified. Additionally, the disclosed hydrogen fuel cell systems can be instantly operated as required, such that operational delay and energy-consuming problems can be prevented. 
     While the invention has been described by way of example and in terms of preferred embodiment, it is to be understood that the invention is not limited thereto. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.