Patent Application
20140131340
This application claims the priority benefit of Taiwan application serial no. 101142261, filed on Nov. 13, 2012. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.
The technical field relates to a heating method of a heating apparatus.
A fuel cell is a device which uses fuel to carry on chemical reactions for generating electricity. The fuel of the fuel cell may be selected from a variety of materials, for example, hydrogen gas, methanol, ethanol, and natural gas.
In an operating fuel cell, the fuel is reacted with oxygen gas through a catalyst to produce water. Some fuel may generate carbon dioxide as well. However, in comparison with other methods for generating electricity, such as thermal power generation, the exhaust amount of carbon dioxide of the operating fuel cell is small, and thus using the fuel cell to generate electricity may be deemed as a low-pollution method.
A direct methanol fuel cell (DMFC) is a device for generating electricity. It converts chemical energy into electricity by directly using methanol (aqueous solution) or methanol gas as the fuel, and the fuel conversion efficiency (i.e., the efficiency of converting chemical energy into electricity) may be changed with the variation in the operative temperatures. In most cases, the fuel efficiency is less than 40%, and the remaining chemical energy is converted into heat. Under normal circumstances, the heat generated by an operating fuel cell is considered as waste heat which needs to be dissipated through a specifically-designed mechanism; alternatively, dissipation of the waste heat may require additional energy. As a result, proper use of the heat generated by the fuel cell may be conducive to improvement of the fuel efficiency.
One of exemplary embodiments includes a heating method of a heating apparatus. The heating apparatus includes a fuel cell, a power storage device, a heat-electricity conversion element, and a switching unit. The fuel cell is adapted for charging the power storage device, and the power storage device is adapted for supplying electricity to the heat-electricity conversion element. The switching unit is adapted for switching the heating apparatus between a first mode and a second mode. The heating method of the heating apparatus includes a first heating process in which the fuel cell charges the power storage device and generates heat during a charging process, and a second heating process in which the power storage device supplies electricity to the heat-electricity conversion element and the heat-electricity conversion element generates heat. The first heating process and the second heating process are performed alternatively when the heating apparatus is switched to the first mode, and the first heating process and the second heating process are performed simultaneously when the heating apparatus is switched to the second mode.
Several exemplary embodiments accompanied with figures are described in detail below to further describe the disclosure in details.
The accompanying drawings are included to provide further understanding, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments and, together with the description, serve to explain the principles of the disclosure.
With reference to
The term “a power storage device” in the disclosure refers to a rechargeable device, and the power storage device may be a secondary battery or a capacitor. For example, a secondary battery may be a lead acid battery, a nickel cadmium battery, a nickel hydride battery, or a lithium ion battery. Of course, the embodiments of the disclosure do not limit the type of the power storage device; as long as the device can be charged by a fuel cell and supply electricity to another electronic element, the device falls within the scope of the disclosure.
The term “a heat-electricity conversion element” refers to an element which can make heat exchange with an external environment by consuming electricity. The term “heat exchange with an external environment” here indicates an action of transferring heat to the external environment. Here, the heat-electricity conversion element may be a resistive heater, for instance. The heat-electricity conversion element may also be a thermoelectric element composed of thermoelectric materials. The thermoelectric element has a cool end and a hot end, and as a result, in the present exemplary embodiment, the heat-electricity conversion element may cool down the external environment or heat up the external environment according to actual requirements.
The operative principle of the fuel cell is to convert chemical energy into electricity through a chemical reaction. Not only electricity but also a large amount of heat may be generated during the reaction. Taking a DMFC with the fuel efficiency of 20.8% as an example, about 4800 Wh (watts×hours) of energy may be obtained by consuming 1 L of methanol, wherein about 1000 Wh of energy is electrical energy, and about 3800 Wh of energy is heat. The heating method described in the exemplary embodiment of the disclosure is a method of exploiting heat generating during the operation of the fuel cell.
In the first embodiment, the heating apparatus 100 is a portable heating apparatus, such as a body-warming apparatus, a camera package, a heat preservation backpack, etc. In consideration of portability, the volume of the fuel cell 102 is often small, and the power output by the fuel cell 102 may be less than 50 W, for example, less than 10 W. Moreover, an internal temperature (that is, the reaction temperature of the chemical reaction in the fuel cell) of an operating fuel cell 102 may be lower than 70° C., for example, lower than 60° C. The fuel cell 102 described in this exemplary embodiment may be arbitrarily placed in any orientation, and the fuel cell 102 may be the one disclosed in Taiwan patent application No. 99144306. The fuel of the fuel cell 102 may be a methanol solution with a concentration greater than 50% v/v, and the fuel with the high concentration directly reacts on an anode of a membrane electrode assembly of the fuel cell 102 without being diluted in a mixing tank.
With reference to
The electricity of the heat-electricity conversion element 106 may be supplied by the power storage device 104, and thus the electricity of the power storage device 104 is reduced gradually as the time goes by. At the time t1, the electricity of the power storage device 104 is reduced to the predetermined lower limit. At this time, a first heating process is performed. In the first heating process, the fuel cell 102 is turned on and generates electricity to charge the power storage device 104. A voltage conversion device (not shown) may be disposed between the fuel cell 102 and the power storage device 104 if necessary. In addition to electricity generation, heat is also generated when the fuel cell 102 is turned on. Therefore, the heat required by the user (QL) can now be supplied by the fuel cell 102, rather than the heat-electricity conversion element 106. As a result, the heat-electricity conversion element 106 can be turned off when the fuel cell 102 is turned on (at the time t1).
In the time frame from t1 to t2, the power storage device 104 is charged by the fuel cell 102, so that the electricity of the power storage device 104 is increased gradually; at the same time, heat is generated by the fuel cell 102 to supply the heat QL. At the time t2, the electricity of the power storage device 104 reaches the predetermined upper limit, so that the fuel cell 102 is turned off. A second heating process is then performed; that is, the heat QL required to be supplied by the heating apparatus 100 is provided by the heat-electricity conversion element 106 now, which is similar to the condition at the time t0.
In this disclosure, “a first heating process” refers to a process in which the fuel cell 102 charges the power storage device 104 and generates heat during the charging process (i.e., the heating process during the time frame from t1 to t2), and “a second heating process” refers to a process in which the power storage device 104 supplies electricity to the heat-electricity conversion element 106, and the heat-electricity conversion element 106 generates heat (i.e., the heating process during the time frame from t0 to t1). The terms “first” and “second” are used to distinguish the two heating processes but not to define the sequence of the two heating processes. As a matter of fact, the first heating process and the second heating process may be performed alternatively (during the time frame from t0 to t2) or simultaneously (which will be described in detail below).
The heating process during the time frame from t2 to t3 is the same as that from t0 to t1; the heating process during the time frame from t3 to t4 is the same as that from t1 to t2, and so on. In case that the heating apparatus 100 is switched to the first mode, the first heating process and the second heating process described above may be constantly performed in an alternative manner. That is, the heating process in the first embodiment can supply heat stably as long as the fuel of the fuel cell 102 has not been completely consumed. To be more specific, the conventional portable heating apparatuses generate heat through consumption of electricity (i.e., the conventional portable heating apparatuses convert electricity into heat); however, after the electricity has been completely consumed, the conventional portable heating apparatuses can no longer generate heat nor generate and store electricity. To generate heat again, the conventional portable heating apparatuses must be charged from the external electricity. By contrast, the heating process described in the first embodiment not only generates heat through consumption of electricity (i.e., the heat-electricity conversion element 106 is applied to convert electricity into heat) but also generates heat at the time of generating and storing electricity (i.e., the fuel cell 102 is applied to convert chemical energy into heat). Thereby, heat may be constantly output to the external environment for a long time.
As shown in
At the time t7, if the heating apparatus 100 is no longer required to output the heat QH, the heating apparatus 100 is switched to the first mode, and thereby the heat-electricity conversion element 106 can be turned off. At this time, the heat QL (with the relatively small amount of heat) output by the heating apparatus 100 may be independently supplied by the fuel cell 102, and the fuel cell 102 may continuously charge the power storage device 104. As a result, the first heating process and the second heating process may be subsequently performed alternately.
In the previous embodiments, the situation in which the heat-electricity conversion element 106 is used to generate heat is described; however, the heat-electricity conversion element 106 may also be employed to perform a cooling process. For example, given that the power storage device 104 is charged by the fuel cell 102, if the fuel cell 102 generates an excessive amount of heat, and the resultant temperature of the heating apparatus 100 is overly high, the heat-electricity conversion element 106 may be switched to a mode in which electricity is consumed to remove the excessive amount of heat; thereby, the temperature of the heating apparatus 100 can be fine tuned.
In addition, based on the user's requirement for heat, the fuel cell may be in an operative mode with low fuel efficiency (i.e., the mode in which the power generation efficiency is reduced and the thermal generation efficiency is increased in case that the same amount of fuel is given) to generate more heat. For instance, the operative voltage may be lowered down, or an increasing amount of fuel may be used for reactions.
Moreover, in this exemplary embodiment, it is not necessary to transmit the electricity of the power storage device 104 only to the heat-electricity conversion element 106. The electricity of the power storage device 104 may be supplied to an external element 108 electrically connected with the power storage device 104 as long as there is a proper power output installed in the heating apparatus 100, as shown in
The heating apparatus 100 may further include a temperature detecting unit (not shown), an electricity detecting unit (not shown), and a control unit (not shown). The temperature detecting unit can detect the temperature of the heating apparatus 100; for example, the temperature detecting unit may be designed to detect the temperature of a portion of the heating apparatus 100 in contact with the human body when the heating apparatus 100 is a body-warming apparatus; the power detecting unit can detect the remaining electricity of the power storage device 104; the control unit can determine whether to turn on/off the fuel cell 102, whether to turn on/off the heat-electricity conversion element 106, and the power of the operating heat-electricity conversion element 106 according to the information obtained from the temperature detecting device and the electricity detecting device. The structures of the aforementioned elements, the actual configurations of these elements, and the circuitry connection correlations among these elements may be known to people having ordinary skill in the pertinent art, and the relevant descriptions may thus be omitted hereinafter.
Experimental examples are listed below to further explain a heating method of a heating apparatus according to the embodiments of the disclosure. However, the disclosure is not limited to the following experimental examples.
The heating apparatus used in experimental example 1 includes a direct methanol fuel cell system which includes a fuel cell, a moisturizing layer at a cathode terminal of the fuel cell, a fuel distribution unit at an anode terminal of the fuel cell, a control unit, a liquid fuel replenishment device, a fuel storage region, and a temperature detecting device. The liquid fuel replenishment device is controlled by the control unit to transfer highly-concentrated methanol fuel (68% of methanol aqueous solution) in the fuel storage region to the fuel distribution unit and further distribute the highly-concentrated methanol fuel to the fuel cell. The temperature detecting device detects an actual temperature of the fuel cell and provides the information about the temperature to the control unit. The control unit controls the operative temperature of the fuel cell to be at most 60° C.
An aluminium plate with a thickness of 300 μm is used as a heat conducting plate, and a resistive heater (a PI film heater occupying an area of 1×3 cm2) is disposed on the aluminium plate. The aluminium plate is in direct contact with the fuel cell to conduct the heat generated by the fuel cell. A lithium ion battery is further disposed in the heating apparatus. Such a structure is used as a basic model of the heating apparatus.
In experimental example 1, under the room temperature at 20° C., the heating process performed by the resistive heater and the heating process resulting from the electricity generation of the fuel cell proceed alternately to stably maintain the temperature of the aluminium plate at 37° C.˜43° C.
The arrangement of the heating apparatus in experimental example 2 is the same as that in experimental example 1. The difference between experimental example 2 and experimental example 1 lies in that experimental example 2 is conducted under the room temperature at 15° C.
As described above, a fuel cell, a heat-electricity conversion element, and a power storage device are collectively employed to conduct a method for using the heat generated by the operating fuel cell. Thus, the fuel efficiency is increased, and the energy may not be wasted. The heating method described in the embodiments of the disclosure can achieve the heating (warming) effects through an electricity generation process and an electricity consumption process, which can proceed alternately or simultaneously. Therefore, the system can be stably operated for a long time without external loads, and stable and long-term heat output may be ensured. At the time of electricity generation together with heat generation, if there is any external electricity requirement, for example, by the peripheral 3C products, electricity may also be supplied thereto.
It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the disclosed embodiments without departing from the scope or spirit of the disclosure. In view of the foregoing, it is intended that the disclosure cover modifications and variations of this disclosure provided they fall within the scope of the following claims and their equivalents.
| Number | Date | Country | Kind |
|---|---|---|---|
| 101142261 | Nov 2012 | TW | national |
