JP2001336823A - Discharged heat recovering device for fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a discharged heat recovering device for a fuel cell from being increased in its size without reducing its efficiency. SOLUTION: A cooling system 2 for use in cooling a fuel cell 1 is comprised of a thermal recovering segment 4 with a fuel cell 1 being applied as a heat source; a cooling segment 10 arranged at the downstream side of the cooling system of the thermal recovering segment 4; a cooling fan 11 for cooling the cooling segment 10; a heat exchanging segment 6 arranged at the downstream side of the cooling system of the cooling segment 10 so as to utilize heat recovered by the thermal recovering segment 4; a hot water feeding system 5 heat exchanging with the heat exchanging segment 6; and a hot water temperature detecting means 12 for use in sensing a temperature of the fed hot water flowing in the hot water feeding system 5, thereby the hot water feeding operation and the cooling operation can be switched without using either the system in a cooling tower or a switched valve and a discharged heat recovering device for a fuel cell having a high efficiency is realized with a simple structure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an exhaust heat recovery device for a fuel cell.

[0002]

2. Description of the Related Art A conventional exhaust heat recovery device for a fuel cell is disclosed in, for example, JP-A-6-44979. Hereinafter, an example of a conventional exhaust heat recovery device for a fuel cell will be described with reference to the drawings. FIG. 3 shows a configuration of a conventional exhaust heat recovery device for a fuel cell. The fuel cell exhaust heat recovery device shown in FIG. 3 includes a fuel cell 1 and a cooling system 2. Since the fuel cell 1 generates power and becomes hot due to reaction heat, the cooling water sent by the cooling water pump 3 in the heat recovery unit 4 adjacent to the fuel cell 1 recovers heat. In order to effectively use the heat recovered by the heat recovery unit 4, a heat exchange unit 6 is provided to exchange heat with hot water for hot water flowing in the adjacent hot water supply system 5. When the temperature of the hot water is low and has not reached the target temperature, the hot water supply operation is performed, and the cooling water having a high temperature in the heat recovery unit 4 exchanges heat with the hot water in the heat exchange unit 6. Then, the low-temperature cooling water circulates and returns to the heat recovery unit 4.
Cools the fuel cell 1. On the other hand, when the hot water temperature rises and reaches the target temperature, the cooling operation is started, the switching valve 8 is opened by the signal S1 from the hot water temperature detecting means 7, and the heat of the cooling water is radiated by the water from the cooling tower 9. Is done.

[0003]

As described above, in the conventional exhaust heat recovery apparatus for a fuel cell as described above, in order to radiate heat of the cooling water during the cooling operation, a cooling tower other than the cooling water system is used. Nine systems are required, and there is a problem that the apparatus becomes large. Further, when switching between the hot water supply operation and the cooling operation, the switching valve 8 is required, and there is a possibility that the efficiency of the fuel cell 1 itself may be reduced due to the power consumption of the valve. Therefore, an object of the present invention is to solve the above-described conventional problems, and specifically, to provide a fuel cell exhaust heat recovery device that can perform heat radiation of cooling water with a simple structure. . Further, an object of the present invention is to switch between the hot water supply operation and the cooling operation without using the switching valve 8,
It is an object of the present invention to provide a method for recovering exhaust heat of a fuel cell with improved efficiency.

[0004]

In order to solve the above problems, the present invention provides a heat recovery unit of the fuel cell as a heat source,
A cooling unit provided on the cooling system downstream of the heat recovery unit, a cooling fan for cooling the cooling unit, and heat provided on the cooling system downstream of the cooling unit and utilizing heat recovered by the heat recovery unit Provided is an exhaust heat recovery device for a fuel cell having a cooling system comprising: an exchange section; a hot water supply system for exchanging heat with the heat exchange section; and a hot water temperature detection means for detecting a temperature of hot water flowing through the hot water supply system. . It is effective that the exhaust heat recovery device further includes means for changing the rotation speed of the cooling fan.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION An exhaust heat recovery apparatus for a fuel cell according to the present invention is provided in a cooling system for cooling the fuel cell, a heat recovery section using the fuel cell as a heat source and a cooling system downstream of the heat recovery section. A cooling unit, a cooling fan that cools the cooling unit, a heat exchange unit that is provided downstream of the cooling system of the cooling unit and uses heat recovered by the heat recovery unit, and a hot water supply system that exchanges heat with the heat exchange unit. And a hot water supply temperature detecting means for detecting a temperature of hot water flowing through the hot water supply system. This makes it possible to switch between the hot water supply operation and the cooling operation without using a cooling tower system or a switching valve, and to achieve a highly efficient exhaust heat recovery device for a fuel cell with a simple structure. In addition, if the cooling fan is configured to be able to change the number of rotations, it is possible to control the hot water supply temperature during the hot water supply operation, and to provide a fuel cell exhaust heat recovery device capable of more detailed and wide-ranging hot water supply temperature control. Can be.

Embodiment 1 FIG. 1 is a diagram showing a configuration of an embodiment of a fuel cell exhaust heat recovery apparatus according to the present invention. In FIG. 1, a cooling unit 10 that radiates heat by cooling air from a cooling fan 11 is provided downstream of the cooling system 2. Hot water temperature detection means 12 compares the target temperature with the temperature of hot water, and outputs signal S2 when the temperature of hot water is lower. Other configurations are the same as those of the conventional fuel cell exhaust heat recovery apparatus shown in FIG. The operation of the heat recovery device for a fuel cell configured as described above will be described.
The cooling water that has exchanged heat with the fuel cell 1 first passes through the cooling unit 10. At this time, when the temperature of the hot water in the hot water supply system 5 is low and has not reached the target temperature, the hot water supply operation is performed, the cooling fan 11 is stopped, and no heat is radiated in the cooling unit 10 of the cooling water. In this state, the cooling water flows to the heat exchange unit 6. Then, the hot water and the cooling water exchange heat to increase the temperature of the hot water, and at the same time, the temperature of the cooling water decreases. Here, when the temperature of the hot water rises and reaches the target temperature, the cooling fan 11 is operated by the signal S2 from the hot water temperature detecting means 12 to perform the cooling operation, and the cooling water is cooled to lower its temperature. Therefore, only the temperature of the cooling water drops, and the hot water and the cooling water do not exchange heat in the heat exchange unit 6. Thus, switching between the hot water supply operation and the cooling operation can be performed without using the system of the cooling tower 9 or the switching valve. Therefore, a highly efficient exhaust heat recovery device for a fuel cell with a simple structure can be provided.

Embodiment 2 FIG. 2 is a diagram showing the configuration of another embodiment of a fuel cell exhaust heat recovery apparatus according to the present invention. In FIG. 2, the cooling fan 13 includes a rotation speed changing unit (for example, a voltage adjusting device that changes the power supply voltage of the cooling fan 13 as a DC fan and changes a power supply voltage) that changes the rotation speed of the cooling fan 13. Further, hot water supply temperature detecting means 14 compares the target temperature with the temperature of hot water, and outputs signal S3 that changes according to the temperature difference. Regarding the heat recovery device for a fuel cell configured as described above,
The operation will be described. First, consider the case where the cooling fan 13 cannot change the rotation speed. During hot water supply operation, if the target temperature of the hot water supply is low and the difference between the hot water temperature before heat exchange is small and the cooling water temperature is higher than the target temperature and the temperature difference with the hot water temperature is large, the hot water temperature and the cooling water become hot. If the hot water is replaced, the temperature of the hot water rapidly rises and becomes higher than the target temperature, so that accurate control may not be performed. Here, according to the present embodiment, when the difference between the target temperature of hot water supply and the temperature of hot water is small, cooling fan 13 operates at a rotation speed lower than the maximum rotation speed by means of hot water temperature detection means 14. However, since the temperature of the cooling water drops, the temperature of the hot water does not rise sharply. The rotation speed change means 15 may be controlled by a computer so that the change in the rotation speed can be appropriately adjusted according to the temperature of the hot water. Thereby, even when the target temperature of hot water supply is low, accurate control of the hot water supply temperature becomes possible. Therefore, it is possible to provide a fuel cell exhaust heat recovery device that can control a wider range of hot water supply temperature.

[0008]

As described above, according to the present invention, it is possible to switch between the hot water supply operation and the cooling operation without using a cooling tower system or a switching valve. Therefore, a highly efficient exhaust heat recovery device for a fuel cell with a simple structure can be provided. Further, even when the target temperature of hot water supply is low, accurate control of the hot water temperature can be performed. Therefore, it is possible to provide a fuel cell exhaust heat recovery device capable of controlling hot water supply temperature more widely.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of an exhaust heat recovery device for a fuel cell according to the present invention.

FIG. 2 is a configuration diagram showing another embodiment of the exhaust heat recovery device for a fuel cell according to the present invention.

FIG. 3 is a configuration diagram showing a conventional exhaust heat recovery device for a fuel cell.

[Brief description of reference numerals]

 DESCRIPTION OF SYMBOLS 1 Fuel cell 2 Cooling system 4 Heat recovery part 5 Hot water supply system 6 Heat exchange part 7 Hot water supply temperature detecting means 10 Cooling part 11 Cooling fan 12 Hot water supply temperature detecting means 13 Cooling fan 14 Hot water temperature detecting means 15 Number of rotation changing means

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Masataka Ozeki 1006 Oaza Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. F term (reference) 5H027 CC06 DD06 KK41

Claims (2)

[Claims] 1. A heat recovery unit of a fuel cell, a cooling unit provided downstream of the cooling system of the heat recovery unit, a cooling fan for cooling the cooling unit, and a cooling fan provided downstream of the cooling unit of the cooling unit. An exhaust heat recovery device for a fuel cell, comprising: a heat exchange unit; a hot water supply system that exchanges heat with the heat exchange unit; and a hot water temperature detection unit that detects a temperature of hot water flowing through the hot water supply system. 2. The fuel cell exhaust heat recovery apparatus according to claim 1, further comprising means for changing a rotation speed of said cooling fan.