U.S. patent application number 10/894261 was filed with the patent office on 2005-01-27 for fuel cell cogeneration system.
This patent application is currently assigned to Matsushita Electric Industrial Co., Ltd.. Invention is credited to Miyauchi, Shinji, Ueda, Tetsuya, Yamamoto, Yoshiaki.
Application Number | 20050019631 10/894261 |
Document ID | / |
Family ID | 34074685 |
Filed Date | 2005-01-27 |
United States Patent
Application |
20050019631 |
Kind Code |
A1 |
Miyauchi, Shinji ; et
al. |
January 27, 2005 |
Fuel cell cogeneration system
Abstract
A fuel cell cogeneration system comprises a fuel cell, a cooling
system for the fuel cell, a heater, a heat utilization portion
configured to store heat recovered in the cooling system to allow
the heat to be consumed, a detector configured to detect calories
remaining in the heat utilization portion, and a controller,
wherein the controller determines whether or not the calories
remaining in the heat utilization portion are at least not less
than the calories required to increase the temperature of the fuel
cell to the operating temperature, and based on determination,
increases the temperature of the fuel cell to the operating
temperature by supplying the remaining calories to the fuel cell
through the cooling system and/or by heating the cooling water in
the cooling system by the heater.
Inventors: |
Miyauchi, Shinji;
(Shiki-gun, JP) ; Ueda, Tetsuya; (Kasugai-shi,
JP) ; Yamamoto, Yoshiaki; (Osaka, JP) |
Correspondence
Address: |
AKIN GUMP STRAUSS HAUER & FELD L.L.P.
ONE COMMERCE SQUARE
2005 MARKET STREET, SUITE 2200
PHILADELPHIA
PA
19103-7013
US
|
Assignee: |
Matsushita Electric Industrial Co.,
Ltd.
|
Family ID: |
34074685 |
Appl. No.: |
10/894261 |
Filed: |
July 19, 2004 |
Current U.S.
Class: |
429/437 ;
429/442 |
Current CPC
Class: |
H01M 8/04052 20130101;
H01M 8/04029 20130101; H01M 8/04425 20130101; F24D 19/1051
20130101; F24D 2220/042 20130101; H01M 8/04373 20130101; F24D
2200/19 20130101; H01M 8/04723 20130101; F24D 2240/26 20130101;
H01M 8/04955 20130101; H01M 8/04738 20130101; Y02E 60/50 20130101;
H01M 8/04037 20130101; H01M 2250/405 20130101; F24D 17/001
20130101; Y02B 90/10 20130101; Y02P 80/15 20151101; Y02B 30/18
20130101; H01M 8/04358 20130101; H01M 8/04059 20130101 |
Class at
Publication: |
429/024 ;
429/026 |
International
Class: |
H01M 008/04 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 23, 2003 |
JP |
2003-278066 |
Claims
What is claimed is:
1. A fuel cell cogeneration system comprising: a fuel cell; a
cooling system configured to circulate an internal heat transfer
medium to allow said fuel cell to exchange heat with the internal
heat transfer medium; a heater configured to heat the internal heat
transfer medium; a heat utilization portion configured to store an
external heat transfer medium to allow consumers to consume the
external heat transfer medium; a heat utilization system configured
to circulate the external heat transfer medium through said heat
utilization portion to allow the internal heat transfer medium in
said cooling system to exchange heat with the external heat
transfer medium; a first detector configured to detect remaining
calories in said heat utilization portion; and a controller,
wherein at start of said fuel cell, said controller determines
whether or not the detected remaining calories in said heat
utilization portion are not less than a threshold which is not less
than fuel cell temperature increasing calories required to increase
a temperature of said fuel cell to an operating temperature,
determines a ratio between a first temperature increasing operation
and a second temperature increasing operation based on
determination as to whether or not the detected remaining calories
are not less than the threshold, the first temperature increasing
operation being performed in such a manner that the remaining
calories in said heat utilization portion are transferred to the
internal heat transfer medium by heat exchange to increase the
temperature of said fuel cell, and the second temperature
increasing operation being performed in such a manner that said
heater heats the internal heat transfer medium to increase the
temperature of said fuel cell, and increases the temperature of
said fuel cell to the operating temperature by both the first
temperature increasing operation and the second temperature
increasing operation or by either the first temperature increasing
operation or the second temperature increasing operation.
2. The fuel cell cogeneration system according to claim 1, wherein
said controller increases the temperature of said fuel cell to the
operating temperature mainly by the first temperature increasing
operation when the remaining calories are not less than the
threshold, and increases the temperature of said fuel cell to the
operating temperature mainly by the second temperature increasing
operation when the remaining calories are less than the
threshold.
3. The fuel cell cogeneration system according to claim 1, further
comprising: a second detector configured to detect a temperature of
the external heat transfer medium stored in said heat utilization
portion, wherein said controller increases the temperature of said
fuel cell to the operating temperature mainly by the second
temperature increasing operation when the remaining calories are
less than the threshold, and said controller determines whether or
not the detected temperature of the external heat transfer medium
is not lower than the operating temperature when the remaining
calories are not less than the threshold, determines the ratio
between the first temperature increasing operation and the second
temperature increasing operation based on determination as to
whether or not the detected temperature is not higher than the
operating temperature, and increases the temperature of said fuel
cell to the operating temperature by both the first temperature
increasing operation and the second temperature increasing
operation or by either the first temperature increasing operation
or the second temperature increasing operation.
4. The fuel cell cogeneration system according to claim 3, wherein
said controller increases the temperature of said fuel cell to the
operating temperature mainly by the first temperature increasing
operation when the temperature of the external heat transfer medium
is not lower than the operating temperature, and increases the
temperature of said fuel cell to the operating temperature mainly
by the second temperature increasing operation when the temperature
of the external heat transfer medium is lower than the operating
temperature.
5. The fuel cell cogeneration system according to claim 1, further
comprising: a third detector configured to detect ambient air
temperature outside said fuel cell, wherein said controller
increases the temperature of said fuel cell to the operating
temperature mainly by the first temperature increasing operation
when the temperature of the external heat transfer medium is not
lower than the operating temperature, and said controller
determines whether or not the temperature of the external heat
transfer medium is not lower than the detected ambient air
temperature when the temperature of the external heat transfer
medium is lower than the operating temperature, determines the
ratio between the first temperature increasing operation and the
second temperature increasing operation based on determination as
to whether or not the temperature of the external heat transfer
medium is not lower than the detected ambient air temperature, and
increases the temperature of said fuel cell by both the first
temperature increasing operation and the second temperature
increasing operation or by either the first temperature increasing
operation or the second temperature increasing operation.
6. The fuel cell cogeneration system according to claim 5, wherein
said controller increases the temperature of said fuel cell to the
operating temperature by using a combination of the first
temperature increasing operation and the second temperature
increasing operation when the temperature of the external heat
transfer medium is not lower than the detected ambient air
temperature, and increases the temperature of said fuel cell to the
operating temperature mainly by the second temperature increasing
operation when the temperature of the external heat transfer medium
is lower than the detected ambient air temperature.
7. The fuel cell cogeneration system according to claim 1, wherein
the threshold includes the fuel cell increasing calories and
predetermined calories, and said controller increases the
temperature of said fuel cell to the operating temperature mainly
by the first temperature increasing operation when the remaining
calories are not less than the threshold, and said controller
increases the temperature of said fuel cell to the operating
temperature mainly by the second temperature increasing operation
when the remaining calories are less than the threshold.
8. The fuel cell cogeneration system according to claim 7, wherein
the predetermined calories are start time period consumed calories
assumed to be consumed by consumers during a start time period from
when said fuel cell starts until a predetermined time elapses.
9. The fuel cell cogeneration system according to claim 8, further
comprising: a fourth detector configured to detect consumed
calories of the external heat transfer medium stored in said heat
utilization portion; a clock configured to measure time; and a
storage configured to store the detected consumed calories and the
measured time, wherein said controller calculates the start time
period consumed calories based on the measured time and the stored
consumed calories.
10. The fuel cell cogeneration system according to claim 9, wherein
said controller obtains the start time period consumed calories by
calculating an average value of consumed calories for a
predetermined period.
11. The fuel cell cogeneration system according to claim 9, wherein
the predetermined calories include a fixed amount and a correction
amount, and said controller changes the correction amount based on
the calculated start time period consumed calories.
12. The fuel cell cogeneration system according to claim 7, further
comprising: a fifth detector configured to detect ambient air
temperature outside said fuel cell, wherein said controller changes
the predetermined calories based on the detected ambient air
temperature.
13. The fuel cell cogeneration system according to claim 7, further
comprising: a sixth detector configured to detect a temperature of
the consumed external heat transfer medium, wherein said controller
changes the predetermined calories according to a frequency at
which the detected temperature of the consumed external heat
transfer medium is not higher than a predetermined value.
14. The fuel cell cogeneration system according to claim 1, wherein
the external heat transfer medium is water, and said heat
utilization portion is a tank.
15. The fuel cell cogeneration system according to claim 14,
wherein the tank is a layered hotwater tank.
16. The fuel cell cogeneration system according to claim 2, wherein
said controller increases the temperature of said fuel cell to the
operating temperature only by the first temperature increasing
operation when the remaining calories are not less than the
threshold, and increases the temperature of said fuel cell to the
operating temperature only by the second temperature increasing
operation when the remaining calories are less than the threshold.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a fuel cell cogeneration
system.
[0003] 2. Description of the Related Art
[0004] FIG. 16 is a block diagram showing a construction of the
conventional fuel cell cogeneration system (see Japanese Laid-Open
Patent Application Publication No. 2002-042841, page 3 to 6, FIG.
1).
[0005] Turning to FIG. 16, the fuel cell cogeneration system
comprises a fuel cell 1 configured to generate an electric power
using a fuel gas and an oxidizing gas, a fuel processor 2
configured to generate the fuel gas by subjecting a material to a
steam reforming reaction and a shift reaction, a fuel-gas
humidifier 5 configured to humidify the fuel gas to be supplied to
the fuel cell 1, an air supply device 6 configured to supply air as
the oxidizing gas to the fuel cell 1, and an oxidizing-gas
humidifier 7 configured to humidify the air.
[0006] The fuel cell cogeneration system further comprises a
cooling pipe 8 through which antifreezing fluid is sent to the fuel
cell 1 to adjust a temperature of the fuel cell 1, a pump 9
configured to circulate cooling water, and a heat exchanger 12
configured to exchange heat generated in the fuel cell 1 with an
external heat transfer medium (e.g., city water). With this
construction, the external heat transfer medium which has exchanged
heat with the fuel cell 1 flows in a direction and is stored in a
heat utilization means 16 such as a tank that recovers heat from
the fuel cell 1, and during start of the fuel cell 1, a heat
transfer controller 17 flows the external heat transfer medium from
the heat utilization means 16 to the fuel cell 1 in a reverse
direction so that the heat recovered by the heat utilization means
16 is transferred to the fuel cell 1 through the heat exchanger
12.
[0007] Like the conventional fuel cell cogeneration system, the use
of the hot water stored in the heat utilization means as the heat
for heating the fuel cell 1 during start, is optimal in terms of
reduction of the start time and energy use efficiency. However,
since consumers typically consume hot water regardless of the
amount of hot water remaining within the heat utilization means,
the hot water may run out with use when the hot water stored in the
heat utilization means is running short. Especially when the heat
utilization means is not internally equipped with a backup hot
water supply device for ensuring the hot water, consumers are
incapable of consuming the hot water. This presents a serious
inconvenience.
SUMMARY OF THE INVENTION
[0008] The present invention has been directed to solving the above
described problem, and an object of the present invention is to
provide a fuel cell cogeneration system capable of inhibiting hot
water from running out and of improving convenience.
[0009] In order to the achieve the above described object, there is
provided a fuel cell cogeneration system comprising: a fuel cell; a
cooling system configured to circulate an internal heat transfer
medium to allow the fuel cell to exchange heat with the internal
heat transfer medium; a heater configured to heat the internal heat
transfer medium; a heat utilization portion configured to store an
external heat transfer medium to allow consumers to consume the
external heat transfer medium; a heat utilization system configured
to circulate the external heat transfer medium through the heat
utilization portion to allow the internal heat transfer medium in
the cooling system to exchange heat with the external heat transfer
medium; a first detector configured to detect remaining calories in
the heat utilization portion; and a controller, wherein at start of
the fuel cell, the controller determines whether or not the
detected remaining calories in the heat utilization portion are not
less than a threshold which is not less than fuel cell temperature
increasing calories required to increase a temperature of the fuel
cell to an operating temperature, determines a ratio between a
first temperature increasing operation and a second temperature
increasing operation based on determination as to whether or not
the detected remaining calories are not less than the threshold,
the first temperature increasing operation being performed in such
a manner that the remaining calories in the heat utilization
portion are transferred to the internal heat transfer medium by
heat exchange to increase the temperature of the fuel cell, and the
second temperature increasing operation being performed in such a
manner that the heater heats the internal heat transfer medium to
increase the temperature of the fuel cell, and increases the
temperature of the fuel cell to the operating temperature by both
the first temperature increasing operation and the second
temperature increasing operation or by either the first temperature
increasing operation or the second temperature increasing
operation.
[0010] The controller may increase the temperature of the fuel cell
to the operating temperature mainly by the first temperature
increasing operation when the remaining calories are not less than
the threshold, and may increase the temperature of the fuel cell to
the operating temperature mainly by the second temperature
increasing operation when the remaining calories are less than the
threshold.
[0011] The fuel cell cogeneration system may further comprise: a
second detector configured to detect a temperature of the external
heat transfer medium stored in the heat utilization portion,
wherein the controller may increase the temperature of the fuel
cell to the operating temperature mainly by the second temperature
increasing operation when the remaining calories are less than the
threshold, and the controller may determine whether or not the
detected temperature of the external heat transfer medium is not
lower than the operating temperature when the remaining calories
are not less than the threshold, may determine the ratio between
the first temperature increasing operation and the second
temperature increasing operation based on determination as to
whether or not the detected temperature is not higher than the
operating temperature, and may increase the temperature of the fuel
cell to the operating temperature by both the first temperature
increasing operation and the second temperature increasing
operation or by either the first temperature increasing operation
or the second temperature increasing operation.
[0012] The controller may increase the temperature of the fuel cell
to the operating temperature mainly by the first temperature
increasing operation when the temperature of the external heat
transfer medium is not lower than the operating temperature, and
may increase the temperature of the fuel cell to the operating
temperature mainly by the second temperature increasing operation
when the temperature of the external heat transfer medium is lower
than the operating temperature.
[0013] The fuel cell cogeneration system may further comprise a
third detector configured to detect ambient air temperature outside
the fuel cell, wherein the controller may increase the temperature
of the fuel cell to the operating temperature mainly by the first
temperature increasing operation when the temperature of the
external heat transfer medium is not lower than the operating
temperature, and the controller may determine whether or not the
temperature of the external heat transfer medium is not lower than
the detected ambient air temperature when the temperature of the
external heat transfer medium is lower than the operating
temperature, may determine the ratio between the first temperature
increasing operation and the second temperature increasing
operation based on determination as to whether or not the
temperature of the external heat transfer medium is not lower than
the detected ambient air temperature, and may increase the
temperature of the fuel cell by both the first temperature
increasing operation and the second temperature increasing
operation or by either the first temperature increasing operation
or the second temperature increasing operation.
[0014] The controller may increase the temperature of the fuel cell
to the operating temperature by using a combination of the first
temperature increasing operation and the second temperature
increasing operation when the temperature of the external heat
transfer medium is not lower than the detected ambient air
temperature, and may increase the temperature of the fuel cell to
the operating temperature mainly by the second temperature
increasing operation when the temperature of the external heat
transfer medium is lower than the detected ambient air
temperature.
[0015] The threshold may include the fuel cell increasing calories
and predetermined calories, and the controller may increase the
temperature of the fuel cell to the operating temperature mainly by
the first temperature increasing operation when the remaining
calories are not less than the threshold, and the controller may
increases the temperature of the fuel cell to the operating
temperature mainly by the second temperature increasing operation
when the remaining calories are less than the threshold.
[0016] The predetermined calories may be start time period consumed
calories assumed to be consumed by consumers during a start time
period from when the fuel cell starts until a predetermined time
elapses.
[0017] The fuel cell cogeneration system may further comprise: a
fourth detector configured to detect consumed calories of the
external heat transfer medium stored in the heat utilization
portion; a clock configured to measure time; and a storage
configured to store the detected consumed calories and the measured
time, wherein the controller may calculate the start time period
consumed calories based on the measured time and the stored
consumed calories.
[0018] The controller may obtain the start time period consumed
calories by calculating an average value of consumed calories for a
predetermined period.
[0019] The predetermined calories may include a fixed amount and a
correction amount, and the controller may change the correction
amount based on the calculated start time period consumed
calories.
[0020] The fuel cell cogeneration system may further comprise a
fifth detector configured to detect ambient air temperature outside
the fuel cell, wherein the controller may change the predetermined
calories based on the detected ambient air temperature.
[0021] The fuel cell cogeneration system may further comprise: a
sixth detector configured to detect a temperature of the consumed
external heat transfer medium, wherein the controller may change
the predetermined calories according to a frequency at which the
detected temperature of the external heat transfer medium is not
higher than a predetermined value.
[0022] The external heat transfer medium may be water, and the heat
utilization portion may be a tank.
[0023] The tank may be a layered hotwater tank.
[0024] The controller may increase the temperature of the fuel cell
to the operating temperature only by the first temperature
increasing operation when the remaining calories are not less than
the threshold, and may increase the temperature of the fuel cell to
the operating temperature only by the second temperature increasing
operation when the remaining calories are less than the
threshold.
[0025] The above and further objects and features of the invention
will more fully be apparent from the following detailed description
with accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] FIG. 1 is a block diagram showing a construction of a fuel
cell cogeneration system according to a first embodiment of the
present invention;
[0027] FIG. 2 is a flowchart showing an operation to select a
temperature increasing means of the fuel cell cogeneration system
in FIG. 1;
[0028] FIG. 3 is a flowchart showing an operation to select a
temperature increasing means of a fuel cell cogeneration system
according to an alternative example 1 of the first embodiment;
[0029] FIG. 4 is a flowchart showing an operation to select a
temperature increasing means of a fuel cell cogeneration system
according to an alternative example 2 of the first embodiment;
[0030] FIG. 5 is a graph showing a time lapse variation in
remaining calories for a day;
[0031] FIG. 6 is a graph showing a time lapse variation in calories
consumed by consumers for a day;
[0032] FIG. 7 is a flowchart showing an operation to select a
temperature increasing means of a fuel cell cogeneration system
according to an alternative example 3 of the first embodiment;
[0033] FIG. 8 is a block diagram showing a construction of a fuel
cell cogeneration system according to a second embodiment of the
present invention;
[0034] FIG. 9 is a flowchart showing an operation to select a
temperature increasing means of the fuel cell cogeneration system
in FIG. 8;
[0035] FIG. 10 is a graph showing a variation in start time period
consumed calories relative to a variation in ambient air
temperature;
[0036] FIG. 11 is a flowchart showing an operation to select a
temperature increasing means of a fuel cell cogeneration system
according to an alternative example 1 of the second embodiment;
[0037] FIG. 12 is a graph showing a time lapse variation in monthly
average start time period consumed calories;
[0038] FIG. 13 is a block diagram showing a construction of a fuel
cell cogeneration system according to a third embodiment of the
present invention;
[0039] FIG. 14 is a flowchart showing an operation to select a
temperature increasing means of the fuel cell cogeneration system
in FIG. 13;
[0040] FIG. 15 is a flowchart showing an operation to select a
temperature increasing means of a fuel cell cogeneration system
according to a fourth embodiment of the present invention; and
[0041] FIG. 16 is a block diagram showing a construction of the
conventional fuel cell cogeneration system.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0042] Hereinafter, embodiments of the present invention will be
described with reference to the drawings.
[0043] (Embodiment 1)
[0044] FIG. 1 is a block diagram showing a construction of a fuel
cell cogeneration system according to a first embodiment of the
present invention.
[0045] Turning to FIG. 1, the fuel cell cogeneration system
(hereinafter simply referred to as cogeneration system) is chiefly
divided into a construction of hardware and a configuration of a
control system.
[0046] First of all, the construction of the hardware will be
described. The cogeneration system comprises a fuel cell 1
configured to generate an electric power using a fuel gas and an
oxidizing gas, a fuel processor 2 configured to generate a fuel gas
from a material and water and to supply the fuel gas to the fuel
cell 1, a fuel-gas humidifier 5 configured, to humidify the fuel
gas being supplied to the fuel cell 1 at a position in a flow path
extending to the fuel cell 1, an air supply device 6 configured to
supply air as an oxidizing gas to the fuel cell 1, and an
oxidizing-gas humidifier 7 configured to humidify the air being
supplied to the fuel cell 1 at a position in a flow path extending
to the fuel cell 1. The fuel processor 2 includes a reformer 3
configured to generate the fuel gas through a steam reforming
reaction of the material and a shifter 4 configured to shift the
fuel gas.
[0047] The cogeneration system comprises a cooling system
configured to cool the fuel cell 1 and a heat utilization system
configured to utilize heat recovered in the cooling system.
[0048] The cooling system includes a cooling water pipe 8 having
ends connected to an inlet and an outlet of a cooling water passage
(hereinafter referred to as an inner passage) 1a of the fuel cell 1
and configured to allow the cooling water (e.g., antifreezing
fluid) as an internal heat transfer medium to flow therethrough, a
cooling water pump 9 provided in the cooling water pipe 8 and
configured to circulate the cooling water, and a heat exchanger 12
provided in the cooling water pipe 8 and configured to exchange
heat owned by the cooling water with an external heat transfer
medium (e.g., stored hot water (city water)). The heat exchanger 12
has a pair of passages, one of which is connected to the cooling
water pipe 8.
[0049] A pipe 31 is provided to connect portions of the pipe 8
which are located on both sides of the heat exchanger 12. A cooling
water heater 100 configured to heat cooling water and a flow rate
control valve 13 are provided in the pipe 31. A flow rate control
valve 14 is provided at a position of the pipe 8 between a position
where the pipe 31 is connected to the pipe 8 and the heat exchanger
12. The cooling water heater 100 is, for example, formed by a
resistance heating type heater and configured to heat the cooling
water by a current supplied from a power supply (not shown)
connected to an electric power system.
[0050] The heat utilization system comprises a tank 16 as a heat
utilization portion, a pair of pipes 15a and 15b, and a circulating
direction switch means 17. The tank 16 employs a layered hotwater
tank. The tank 16 is tubular and provided such that its center axis
extends in a vertical direction. An upper end of the tank 16 is
connected to one end of the other of the pair of passages of the
heat exchanger 12 through a pipe 15a, and a lower end of the tank
16 is connected to the other end of the other of the passages of
the heat exchanger 12 through a pipe 15b. And, the circulating
direction switch means 17 is located in the pipe 15b.
[0051] The circulating direction switch means 17 includes a stored
hot water pump 20 configured to circulate the external heat
transfer medium, a discharge joint 23 and a suction joint 24
respectively connected to a discharge port and a suction port of
the pump 20, a first passage switch valve 21 connected to a portion
of the pipe 15b on the heat exchanger 12 side, the discharge joint
23, and the suction joint 24, and a second passage switch valve 22
connected to a portion of the pipe 15b on the tank 16 side, the
suction joint 24, and the discharge joint 23. In this construction,
when in the circulating direction switch means 17, the first
passage switch valve 21 is switched so that the portion of the pipe
15b on the heat exchanger 12 side is connected to the suction joint
24, and the second passage switch valve 22 is switched so that the
portion of the pipe 15b on the tank 16 side is connected to the
discharge joint 24, the hot water circulates as indicated by an
arrow B in such a manner that the hot water is taken out from the
upper end of the tank 16 and returns to the lower end of the tank
16. On the other hand, when in the circulating direction switch
means 17, the first passage switch valve 21 is switched so that the
portion of the pipe 15b on the heat exchanger 12 side is connected
to the discharge joint 23, and the second passage switch valve 22
is switched so that the portion of the pipe 15b on the tank 16 side
is connected to the suction joint 24, the hot water circulates as
indicated by an arrow A in such a manner that the hot water is
taken out from the lower end of the tank 16 and returns to the
upper end of the tank 16.
[0052] The heat utilization system includes a pipe 32 connected to
the lower end of the tank 16 to allow the city water to be supplied
therethrough, and a pipe 33 connected to the upper end of the tank
16 to allow the hot water stored in the tank 16 to be supplied to
consumers. In this construction, the city water sent to the tank 16
through the pipe 32 is heated by heat recovered from the fuel cell
1 and converted into hot water, which is taken out and supplied to
consumers through the pipe 33.
[0053] Next, the configuration of the control system will be
described. The cogeneration system includes a controller 201, first
to third tank temperature sensors 101A to 101C each configured to
detect remaining calories in the tank 16 and output signals
indicating temperatures of the tank 16, a meter 102 configured to
detect consumed calories, a stack temperature sensor 202 configured
to detect a temperature of a stack of the fuel cell 1 and output a
signal indicating the temperature, a first heat exchanger sensor 18
and a second heat exchanger temperature sensor 19. The controller
201 is configured by a processor, and includes a processor 105, a
storage 104, and a clock 103. Herein, as the processor, a
microcomputer is used. The processor 105 is CPU, and the storage
104 is semiconductor memory such as ROM or RAM.
[0054] The first to third temperature sensors 101A to 101C are each
formed by, for example, thermistor or thermocouple, and attached to
be capable of detecting a vertical temperature distribution of the
tank 16. The first to third temperature sensors 101A to 101C are
positioned at centers of surfaces of an upper portion 16a, a center
portion 16b, and a lower portion 16b of the tank 16,
respectively.
[0055] The signals output from the sensors 101A to 101C are input
to the processor 105 of the controller 201.
[0056] The stack temperature sensor 202 is formed by, for example,
thermistor or thermocouple, and provided on the stack of the fuel
cell 1. The signal output from the stack temperature sensor 202 is
input to the processor 105 of the controller 201.
[0057] The meter 102 is attached to the pipe 33 through which the
stored hot water is supplied to the consumers. The meter 102 is
configured to detect a flow rate of the stored hot water and output
a signal indicating the flow rate. The signal output from the flow
meter 102 is input to the processor 105 of the controller 201.
[0058] The first and second heat exchange sensors 18 and 19 are
each formed by, for example, thermistor. The first heat exchanger
temperature sensor 18 is attached to the pipe 15a in the vicinity
of a position where the pipe 15a is connected to the heat exchanger
12, and the second heat exchanger temperature sensor 19 is attached
to the pipe 15b in the vicinity of a position where the pipe 15b is
connected to the heat exchanger 12. Signals output from the first
and second heat exchange temperature sensors 18 and 19 are input to
the processor 105 of the controller 201.
[0059] The processor 105 is configured to control ON and OFF of the
cooling water heater 100 and an operation of the circulating
direction switch means 17.
[0060] Although not shown, signals output from desired sensors in
the cogeneration system are input to the processor 105, and desired
components in the cogeneration system are controlled by the
processor 105. The processor 105 performs calculation and
processing based on various inputs, and outputs control signals to
the components, thereby controlling the cogeneration system
including a control for selecting a temperature increasing
means.
[0061] Subsequently, an operation of the cogeneration system
constructed as described above will be described. As described
above, this operation is carried out under control of the
controller 201. It should be appreciated that the controller 201 is
always operating, to be precise, after the cogeneration system is
installed.
[0062] First, a typical operation will be described. The
cogeneration system has three types of operation modes, i.e., a
start mode, an operation mode, and a stop mode. In the start mode,
the cogeneration system carries out a predetermined operation to
start smoothly and safely. In the operation mode, the cogeneration
system generates an electric power. And, in the stop mode, the
cogeneration system performs a predetermined operation to stop
smoothly and safely.
[0063] Turning to FIG. 1, more specifically, in the operation mode,
a feed gas and water are supplied to the reformer 3, which
generates a fuel gas containing hydrogen-rich gas. The fuel gas is
supplied to the shifter 4, where concentration of hydrogen of the
fuel gas is enhanced through the shift reaction. The resulting fuel
gas is supplied to the fuel-gas humidifier 5 and humidified
therein. Then, the humidified fuel gas is supplied to a fuel
electrode (not shown) of the fuel cell 1.
[0064] Meanwhile, the air is supplied as the oxidizing gas from the
air supply device 6 to the oxidizing-gas humidifier 7 and
humidified therein. The humidified air is supplied to an air
electrode (not shown) of the fuel cell 1. The oxidizing gas reacts
with the fuel of the fuel electrode and thereby generates
electricity and heat.
[0065] The fuel and the oxidizing gas remaining unconsumed after
the above reaction are discharged outside the fuel cell 1. The
generated electricity is supplied to a load or the like through an
output portion (not shown).
[0066] In the cooling system and the heat utilization system, in
the operation mode, the flow rate control valve 13 is fully closed
and the flow rate control valve 14 is fully opened. The cooling
water pump 9 causes the cooling water to circulate through an
internal passage 1a of the fuel cell 1, the pipe 8, and the heat
exchanger 12. Thereby, heat (waste heat) generated in the fuel cell
1 is recovered from the fuel cell 1 by the cooling water, and
thereby the fuel cell 1 is cooled. The recovered heat is
transferred to the hot water within the heat exchanger 12.
[0067] In the circulating direction switch means 17, the first
passage switch valve 21 is switched so that the portion of the pipe
15b on the heat exchanger 12 side is connected to the discharge
joint 23, and the second passage switch valve 22 is switched so
that the portion of the pipe 15b on the tank 16 side is connected
to the suction joint 24, so that the stored hot water pump 20
causes the hot water to circulate in A direction in such a manner
that the water is taken out from the lower end of the tank 16 and
returns to the upper end of the tank 16. As a result, within the
heat exchanger 12, heat is transferred (recovered) from the cooling
water to the hot water and the cooling water is thereby cooled. The
hot water that has increased the temperature by the heat
transferred from the cooling water is stored in the tank 16 to have
a layered temperature distribution in which the temperature
increases from the lower side to the upper side. Thus stored hot
water is consumed by the consumers as desired through the pipe 33
and a water supply terminal such as a faucet. Then, the city water
is supplied to the tank 16 through the pipe 32 to replenish the
consumed hot water.
[0068] Subsequently, the operation to select the temperature
increasing means will be described with reference to FIGS. 1 and 2.
FIG. 2 is a flowchart showing an operation to select the
temperature increasing means of the cogeneration system in FIG.
1.
[0069] Turning to FIGS. 1 and 2, in the operation to select the
temperature increasing means, the processor 105 of the controller
201 calculates remaining calories Q of the tank 16 (Step S1) as
described below.
[0070] More specifically, temperatures of the upper portion 16a,
the center portion 16b, and the lower portion 16c of the tank 16
are input sequentially from the first to third tank sensors 101A to
101C to the processor 105, respectively. The processor 105
calculates the remaining calories Q in the tank 16 as described
below. First, the processor 105 multiplies a product of a volume of
the upper portion 16a of the tank 16 and the temperature of the
upper portion 16a of the tank 16 which is input from the first
temperature processor 105 by a predetermined coefficient, thus
calculating remaining calories in the upper portion 16a of the tank
16. And, the processor 105 multiplies a product of a volume of the
center portion 16b of the tank 16 and the temperature of the center
portion 16b of the tank 16 which is input from the second
temperature sensor 105B by a predetermined coefficient, thus
calculating remaining calories in the center portion 16b of the
tank 16. And, the processor 105 multiplies a product of a volume of
the lower portion 16c of the tank 16 and the temperature of the
lower portion 16c of the tank 16 which is input from the third
temperature sensor 101C by a predetermined coefficient, thus
calculating remaining calories in the lower portion 16c of the tank
16. Then, these calories are added to obtain the remaining calories
Q in the tank 16. It should be appreciated that the volumes of the
portions 16a to 16c of the tank 16 may be measured by
experiments.
[0071] Then, the processor 105 calculates calories (hereinafter
referred to as fuel cell temperature increasing calories) QF
required to increase the fuel cell 1 up to an operating temperature
(Step S2). Specifically, the signal is input from the stack
temperature sensor 202 to the processor 105, which converts the
signal to obtain the stack temperature. In the storage 104 of the
controller 201, the operating temperature of the fuel cell 1 and a
calorific capacity of the stack are stored. The processor 105 reads
out these from the storage 104, and multiplies a difference between
the operating temperature of the fuel cell 1 and the input stack
temperature by the calorific capacity of the stack, thus
calculating the fuel cell temperature increasing calories QF. In
order to simplify the calculation, a fixed value of the fuel cell
temperature increasing calories QF may be stored in the storage 104
and read out as desired without considering the stack
temperature.
[0072] Subsequently, the processor 105 determines whether or not
the fuel cell 1 is going to start (Step S3). As described above,
the controller 201 is always operating (i.e., in ON state), and
therefore, in the cogeneration system, portions other than the
controller 201 start and stop. As used herein, "start time of the
fuel cell 1" refers to a time at which a control signal to cause
the fuel cell 1 to start the start mode is output from the
controller 201 to the fuel cell 1. The time determined by the
processor 105 is not intended to be limited to the above "start
time", but may be a suitable time in the start mode according to
the design.
[0073] If it is determined that the fuel cell 1 is not going to
start, the processor 105 returns to Step S1. On the other hand, if
it is determined that the fuel cell 1 is going to start in Step S3,
the processor 105 determines whether or not the remaining calories
Q of the tank 16 are not less than the fuel cell temperature
increasing calories QF (i.e., threshold calories and hereinafter
referred to as a temperature increasing means select threshold QLT)
(Step S4).
[0074] If it is determined that the remaining calories Q are not
less than the temperature increasing calories QF in Step S4, the
remaining calories Q are consumed to increase the temperature of
the fuel cell 1 (Step S5), whereas if it is determined that the
remaining calories Q are less than the temperature increasing
calories QF in Step S4, the cooling water heater 100 is used to
increase the temperature of the fuel cell 1 (Step S6).
[0075] Hereinafter, these temperature increasing operations will be
described more specifically. When the remaining calories Q of the
tank 16 are consumed to increase the temperature of the fuel cell
1, the flow rate control valve 14 of the cooling system is fully
opened, the flow rate control valve 13 is fully closed, and the
cooling water pump 9 is operated. Also, in the circulating
direction switch means 17, the first passage switch valve 21 is
switched so that the portion of the pipe 15b on the heat exchanger
12 side is connected to the suction joint 24, and the second
passage switch valve 22 is switched so that the portion of the pipe
15b on the tank 16 side is connected to the discharge joint 23, and
the stored hot water pump 20 is operated. The pump 20 causes the
hot water to circulate as indicated by the arrow B in such a manner
that the hot water is taken out from the upper end of the tank 16
and returns to the lower end of the tank 16. Thereby, the heat
stored in the tank 16 is transferred from the hot water to the
cooling water within the heat exchanger 12. The resulting cooling
water flows through the internal passage 1a of the fuel cell 1 and
the heat from the cooling water increases the temperature of the
fuel cell 1.
[0076] Meanwhile, when the cooling water heater 100 is used to
increase the temperature of the fuel cell 1, the flow rate control
valve 14 of the cooling system is fully closed, the flow rate
control valve 13 is fully opened, and the cooling water pump 9 is
operated. In the circulating direction switch means 17, the pump 20
is stopped. Thereby, the cooling water heated by the cooling water
heater 100 flows through the internal passage 1a within the fuel
cell 1 and thereby increases the temperature of the fuel cell
1.
[0077] As should be appreciated from the foregoing, in the first
embodiment, only when the remaining calories Q of the tank 16 are
not less than the temperature increasing calories QF required to
increase the temperature of the fuel cell 1, the remaining calories
Q are consumed to increase the temperature of the fuel cell 1
without the use of the cooling water heater 100. This makes it
possible to inhibit the hot water from running out due to the
temperature increase in the fuel cell 1.
[0078] [Alternative Example 1 of Embodiment 1]
[0079] An alternative example 1 of the first embodiment will now be
described.
[0080] FIG. 3 is a flowchart showing an operation to select a
temperature increasing means in a fuel cell cogeneration system
according to the alternative example 1.
[0081] The construction of the alternative example 1 is
substantially identical to that of the first embodiment in FIGS. 1
and 2 except for the operation to select the temperature increasing
means under control of the controller 201. Specifically, as shown
in FIGS. 1 and 3, the processor 105 of the controller 201
calculates the fuel cell temperature increasing calories QF in Step
S2, and thereafter obtains stored hot water temperature TW and fuel
cell operating temperature TO in Step S11. More specifically, the
processor 105 converts the signal indicating the temperature of the
upper portion 16a of the tank 16 which is input from the first tank
temperature sensor 101A into a temperature according to a
predetermined formula, and uses this converted temperature as
stored hot water temperature TW. Also, the operating temperature TO
of the fuel cell 1 is prestored in the storage 104 of the
controller 201. The processor 105 reads out the operating
temperature TO from the storage 104 to thereby obtain it.
[0082] If it is determined that the remaining calories Q are not
less than the temperature increasing calories QF in Step S4,
thereafter, the processor 105 determines whether or not the stored
hot water temperature TW is not lower than the operating
temperature TO (Step S12). If it is determined that the stored hot
water temperature TW is not lower than the operating temperature TO
in Step S12, the remaining calories Q are used to increase the
temperature of the fuel cell 1 in Step S5, whereas if it is
determined that the temperature TW is lower than the operating
temperature TO in Step S12, the cooling water heater 100 is used to
increase the temperature of the fuel cell 1 in Step S6. In other
respect, the operation is identical to the operation in FIG. 2.
[0083] Consequently, it is possible to reliably increase the
temperature of the fuel cell 1 to the predetermined operating
temperature.
[0084] [Alternative Example 2 of Embodiment 1]
[0085] An alternative example 2 of the first embodiment will now be
described. FIG. 4 is a flowchart showing an operation to select a
temperature increasing means of a fuel cell cogeneration system
according to the alternative example 2 of the first embodiment.
FIG. 5 is a graph showing a time lapse variation in remaining
calories for a day. FIG. 6 is a graph showing a time lapse
variation in calories consumed by consumers for a day.
[0086] The construction of the alternative example 2 is
substantially identical to that of the first embodiment in FIGS. 1
and 2 except for the operation to select the temperature increasing
means under control of the controller 201. Specifically, as shown
in FIGS. 1 and 4, the processor 105 of the controller 201
calculates the remaining calories Q according to the above
described method in Step S1, and stores the calculated remaining
calories Q and time input from the clock 103 as associated with
each other in the storage 104. The remaining calories Q are stored
per day. Data of the remaining calories Q corresponding to a
predetermined days from now are stored, and sequentially erased
(overwritten) after an elapse of the predetermined days.
[0087] Then, the processor 105 calculates the temperature
increasing calories QF in Step S2, and thereafter, calculates
consumed calories E in Step S13. Specifically, the flow rates of
the stored hot water (hereinafter expressed as supplied hot water)
consumed through the pipe 33 are sequentially input from the meter
102 to the processor 105 of the controller 102. And, the
temperatures of the upper portion 16a of the tank 16 are
sequentially input from the first temperature sensor 101A of the
processor 105. The processor 105 multiplies a product of the flow
rate of the supplied hot water input from the meter 102 and the
temperature of the upper portion 16a of the tank 16 which is input
from the first tank temperature sensor 101A by a predetermined
coefficient, thus calculating the calories E consumed by the
consumers. The consumed calories E and the time input from the
clock 103 are stored as associated with each other in the storage
104. The consumed calories E are stored per day. Data of the
consumed calories E corresponding to a predetermined days from now
are stored, and sequentially erased (overwritten) after an elapse
of the predetermined days.
[0088] Then, the processor 105 determines whether or not the fuel
cell 1 is going to start (Step S3). The Steps S1, S2, S13, and S3
are repeated until the fuel cell 1 starts. When the fuel cell 1
starts, the processor 105 determines whether or not the remaining
calories Q of the tank 16 are not less than a total of temperature
increasing calories QF and start time period consumed calories ESA
of the consumed calories E (Step S4).
[0089] If it is determined that the remaining calories Q are not
less than the total of the temperature increasing calories QF and
the start time period consumed calories ESA in Step S4, the
remaining calories Q are consumed to increase the temperature of
the fuel cell 1 (Step S5), whereas when the remaining calories Q
are less than the total of the temperature increasing calories QF
and the start time period consumed calories ESA, the cooling water
heater 100 is used to increase the temperature of the fuel cell 1
(Step S5).
[0090] Subsequently, how the temperature increasing means is
determined will be described in detail. The processor 105 repeats
the operations in Steps S1, 2, 13, and 4 to 6, and thereby the time
lapse variation in the calories consumed per day and the time lapse
variation in the remaining calories per day are stored in the
storage 104.
[0091] The consumed calories (substantially the amount of supplied
hot water) E varies with an elapse of time per day as represented
by a solid line in FIG. 6. Turning to FIG. 6, calories are consumed
around six a.m., around twelve at noon, and around eighteen to
twenty four during a time period from the evening to night. In
particular, consumed calories ES1 around eighteen to twenty four
are more than the others. In this case, the remaining calories Q of
the tank 16 vary as represented by a solid line in FIG. 5, and
finally becomes Q1 at the end of the day (around twenty four).
[0092] In this alternative example 2, the cogeneration system is
configured to automatically start and stop. The cogeneration system
starts around six in the morning (time t1) and stops around twenty
four at night. Also, in the alternative example 2, the consumed
calories E as a reference to be used for determining the
temperature increasing means are determined considering life
pattern of the consumers. Specifically, consumed calories ES2
during the start time period (period tA (time: t1 to t2) are used
as a reference for determination and hereinafter referred to as
start time period consumed calories ESA. As used herein, "start
time period" means a time period from when the cogeneration system
starts until calorie consumption started upon start of the system
or after the start of the system stops for a predetermined time
period or longer. In the alternative example 2, the predetermined
time period is 60 minutes, but is not intended to be limited to
this, because the frequency at which the consumers consume calories
varies depending on how the consumers consume calories or the
number of consumers. For example, when the consumers consume
calories frequently or many consumers consume calories, the
predetermined time period is required to be set longer, whereas
when the consumers consume calories less frequently or the number
of consumers is less, the predetermined time period is required to
be set shorter. Thus, "start time period" can be determined
according to now the calories are actually consumed.
[0093] When the time lapse variation in the remaining calories Q
and the time lapse variation in the consumed calories E in a day
are represented by solid lines in FIGS. 5 and 6, the processor 105
determines, at start (time t1) of the fuel cell 1 in the following
day in Step S4, whether or not calories Q1 of the remaining
calories Q are not less than a total of consumed calories ES2 of
the start time period consumed calories ESA and the temperature
increasing calories QF. Here it is assumed that the remaining
calories Q1 are less than the total of the consumed calories ES2
and the temperature increasing calories QF. In this case, the
processor 105 determines that the remaining calories Q are less
than the total of the temperature increasing calories QF and the
start time period consumed calorie ESA, and uses the cooling water
heater 100 to increase the temperature of the fuel cell 1 (Step
S6). This makes it possible to inhibit the hot water from running
out in the case where the calories (ES2) are assumed to be consumed
during start of the fuel cell 1 according to the life pattern. In
FIG. 5, reduction amount QL1 of the remaining calories Q during a
time period tA corresponds to a total of the consumed calories ES2
and the temperature increasing calories QF.
[0094] When calories ES3 consumed during the time period from
eighteen to twenty four in that day are less as indicated by a
dashed line in FIG. 6, the remaining calories Q of the tank 16
finally become Q2 as indicated by a dashed line in FIG. 5. Here it
is assumed that the remaining calories Q2 are more than the total
of the consumed calories ES3 and the temperature increasing
calories QF. In this case, at start of the fuel cell 1 in the
following morning, the processor 105 determines that the remaining
calories Q are not less than the total of the temperature
increasing calories QF and the start time period consumed calories
ESA in Step 54 and starts the fuel cell 1 using the remaining
calories Q. By doing so, in the cogeneration system, the
temperature of the fuel cell 1 is increased while ensuring the
consumed calories ES2 during the time period tA. This results in
reduction QL2 of the remaining calories Q corresponding to the
total of the consumed calories ES2 caused by hot water supply and
the temperature increasing calories QF during the time period tA,
but the hot water will not run out at the end t2 of consumption of
the hot water.
[0095] As should be appreciated from the foregoing, in accordance
with the alternative example 2, the recovered heat can be
efficiently utilized during start of the fuel cell 1 depending on
the remaining calories Q stored in the tank 16 during the operation
without running out the hot water to be consumed by consumers.
[0096] While the consumed calories ES2 during the start time period
tA in preceding (previous) day are employed as the start time
period consumed calories ESA, a fixed value may be set as the
calories ESA for the sake of simplicity.
[0097] [Alternative Example 3 of Embodiment 1]
[0098] An alternative example 3 of the first embodiment will be
described. In the alternative example 2, the threshold QLT for
determination of the temperature increasing means is set
considering the life pattern of the consumers. Specifically, the
consumed calories ES2 during the start time period tA in the
previous day are used as the start time period consumed calories
ESA. However, the consumed calories ES2 vary from one day to
another. Especially when the difference in the consumed calories
ESA between a day and a previous day is large, it may be impossible
to appropriately inhibit the hot water from running out. The
alternative example 3 of the first embodiment is directed to
solving this problem.
[0099] FIG. 7 is a flowchart showing an operation to select a
temperature increasing means of a fuel cell cogeneration system
according to the alternative example 3.
[0100] The alternative example 3 differs from the alternative
example 2 in the following respects. Turning to FIG. 7, if it is
determined that the fuel cell 1 is not going to start in Step S3,
the processor 105 calculates an average value ESAA for each
predetermined time period of the start time period consumed
calories ESA (consumed calories ES2 during the time period tA in
the start time period), and stores the average value (hereinafter
expressed as average start time period consumed calories) ESAA of
the start time period consumed calories ESA in the storage 104. As
the predetermined period, for example, one week, one month, or
season is used. The average start time period consumed calories
ESAA are updated in each period longer than the predetermined
period.
[0101] In Step S4, the processor 105 determines whether or not the
remaining calories Q are not less than the total of the temperature
increasing calories QF and the average start time period consumed
calories ESAA. In other respect, the alternative example 3 is
similar to that of the alternative example 2.
[0102] In accordance with the alternative example 3 of the first
embodiment, since the average value ESAA is used as the start time
period consumed calories ESA which is considered to determine the
temperature increasing means select threshold QLT, variation in the
threshold QLT becomes smaller, and it is possible to inhibit the
hot water from running out when the difference in the consumed hot
water between a day and a previous day is large.
[0103] (Embodiment 2)
[0104] Although the temperature increasing means select threshold
QLT is set considering the life pattern of consumers in the
alternative examples 2 and 3 of the first embodiment, the life
pattern of the consumers varies depending on seasonal change. In
general, the calories used for hot water supply or air conditioning
in the morning tend to increase as ambient air temperature
decreases. In the second embodiment, the threshold OLT is set
considering the variation in the consumed calories during the start
time period due to such seasonal change.
[0105] FIG. 8 is a block diagram showing a construction of a fuel
cell cogeneration system according to the second embodiment of the
present invention. In FIG. 8, the same reference numerals as those
in FIG. 1 denote the same or corresponding parts which will not be
further described.
[0106] In the second embodiment, an ambient air temperature sensor
106 is attached at a proper position to detect ambient air
temperature. A signal indicating the detected temperature is input
from the ambient air temperature sensor 106 to the processor 105 of
the controller 201. Considering the detected ambient air
temperature, the processor 105 selects the temperature increasing
means. As the ambient air sensor 106, a temperature sensor such as
thermistor is used. In other construction, the second embodiment is
similar to the first embodiment (construction in FIGS. 1 and
2).
[0107] Subsequently, an operation of the cogeneration system so
constructed will be described. FIG. 9 is a flowchart showing an
operation to select a temperature increasing means of the
cogeneration system in FIG. 8. In FIG. 9, the same reference
numerals as those in FIG. 4 denote the same or corresponding steps
which will not be further described.
[0108] Turning to FIGS. 8 and 9, in the second embodiment, the
processor 105 calculates the fuel cell temperature increasing
calories QF in Step S2, and thereafter, calculates correction
amount QH based on the ambient air temperature in Step S15. And, in
Step S4, the processor 105 determines whether or not the remaining
calories Q are not less than a total of the temperature increasing
calories QF, reference start time period consumed calories QA, and
the correction amount QH. The other configuration is identical to
that of the first embodiment in FIGS. 1 and 2.
[0109] Hereinafter, the difference between the first embodiment and
the second embodiment will be described in detail.
[0110] FIG. 10 is a graph showing a variation in start time period
consumed calories ESA relative to a variation in ambient air
temperature TA (ambient air temperature--start time period consumed
calorie characteristic and hereinafter simply expressed as
characteristic).
[0111] In general, during the start time period tA, the consumed
calories increase as the ambient air temperature decreases. In the
second embodiment, the characteristic is prestored in the storage
104 of the controller 201. The characteristic is obtained from, for
example, experiment or simulation. FIG. 10 shows an example of the
characteristic. And, the reference start time period consumed
calories (hereinafter referred to as reference calories) QA for
setting the temperature increasing means select threshold QLT using
the characteristic is stored in the storage 104. The reference
calories QA may be set to a desired value. Herein, the reference
calories QA are set to start time period consumed calories
corresponding to standard ambient air temperature in the
characteristic.
[0112] In Step S15, the processor 105 converts the signal input
from the ambient air temperature sensor 106 into the ambient air
temperature TA and obtains it, and reads out the characteristic and
the reference start time period consumed calories QA from the
storage 104. And, the processor 10 obtains a difference .DELTA.AESA
between the start time period consumed calories ESA (ESA1 in FIG.
10) corresponding to the ambient air temperature TA (TA1 in FIG.
10) on the characteristic and the reference calories QA as
correction amount QH.
[0113] And, in Step S4, if it is determined that the remaining
calories Q are not less than a total of the temperature increasing
calories QF, the reference calories QA, and the correction amount
QA, that is,
Q.gtoreq.QF+QA+QH=QLT
[0114] the remaining calories Q are consumed to increase the
temperature of the fuel cell 1 (Step S5).
[0115] On the other hand, if it is determined that the remaining
calories Q are less than the total of the temperature increasing
calories QF, the reference calories QA, and the correction amount
QH, that is,
Q<QF+QA+QH=QLT
[0116] the cooling water heater 100 is used to increase the
temperature of the fuel cell 1 (Step S6).
[0117] In accordance with the second embodiment, since the
variation in the consumed calories during the start time period tA
due to seasonal change may be accommodated by automatically
correcting the temperature increasing means select threshold QLT,
it is possible to achieve convenient and energy-saving cogeneration
system capable of inhibiting hot water from running out.
[0118] While the above-identified characteristic is obtained from,
for example, experiment, the characteristic may alternatively
obtained in such a manner that the start time period consumed
calories ESA are calculated as in the first embodiment, the
calculated calories ESA and the ambient air temperature TA detected
by the ambient air temperature sensor 106 is stored in the storage
104 of the controller 201, and the processor 105 is statistically
process the calories ESA and the ambient air temperature TA stored
in the storage 104 by regression analysis, thereby obtaining the
characteristic.
[0119] [Alternative Example 1 of the Embodiment 2]
[0120] An alternative example 1 of the second embodiment will now
be described.
[0121] In the alternative example 1, the ambient air temperature
sensor 106 configured to detect the ambient air temperature, which
is shown in FIG. 8, is omitted. And, the processor 105 calculates
monthly average start time period consumed calories and selects
temperature increasing means based on the monthly average start
time period consumed calories. This follows that the temperature
increasing means is selected considering the ambient air
temperature. The other construction is identical to that in FIGS. 8
and 9.
[0122] Hereinafter, the difference between the construction of the
alternative example 1 and the construction in FIGS. 8 and 9 will be
described.
[0123] FIG. 11 is a flowchart showing an operation to select a
temperature increasing means of a fuel cell cogeneration system
according to the alternative example 1 of the second embodiment.
FIG. 12 is a graph showing a time lapse variation in monthly
average start time period consumed calories in the fuel cell
cogeneration system of the alternative example 1.
[0124] Turning to FIGS. 8 and 11, in the alternative example 1 of
the second embodiment, the processor 105 calculates the fuel cell
temperature increasing calories QF in Step S2 and then calculates
consumed calories E in Step S13 as in the alternative example 2 of
the first embodiment.
[0125] Thereafter, the processor 105 calculates correction amount
QH based on ambient air temperature in Step S15. And, if it is
determined that the fuel cell 1 is not going to start in Step S3,
thereafter, the processor 105 creates a monthly start time period
consumed calorie variation curve in Step S14'. The other
configuration is identical to that of the operation to select the
temperature increasing means in FIG. 9.
[0126] The processor 105 creates the curve in Step S14' in such a
manner that the start time period consumed calories SEA of the
consumed calories E calculated in Step S13 are added for each
month, and divided by the number of days in each month to obtain
monthly average start time period consumed calories ESAA, and the
calories ESAA are stored in the storage 104 as associated with the
each month. For example, this data for the last one year from now
are stored, and are sequentially erased (or overwritten) after an
elapse of one year. As shown in FIG. 12, the processor 105 linearly
interpolates plots of monthly average start time period consumed
calories ESAA for the last one year on time axis monthly average
start time period consumed calories ESAA axis plane to create the
time lapse variation curve of the monthly average start time period
consumed calories ESAA for one year (hereinafter expressed as
monthly start time period consumed calorie variation curve) and
stores the curve in the storage 104.
[0127] The reference start time period consumed calories QA for
setting the temperature increasing means select threshold QLT using
the monthly start time period consumed calorie variation curve are
stored. The reference calories QA may be set to a desired value,
but is set to standard monthly start time period consumed calories
in the monthly start time period consumed calorie variation
curve.
[0128] In Step S15, the processor 105 obtains current time from the
clock 103 and reads out the monthly start time period consumed
calorie variation curve and the reference calories QA from the
storage 104. And, the processor 105 obtains a difference
.DELTA.ESAA between the monthly average start time period consumed
calories ESAA (ESAA1 in FIG. 12) corresponding to the current time
t (t3 in FIG. 12) on the monthly start time period consumed calorie
variation curve, and the reference calories QA as correction amount
QH.
[0129] In Step S4, if it is determined that the remaining calories
Q are not less than a total of the fuel cell temperature increasing
calories QF, the reference calories QA, and the correction amount
QA, that is,
Q.gtoreq.QF+QA+QH=QLT
[0130] the remaining calories Q are consumed to increase the
temperature of the fuel cell 1 (Step S5).
[0131] On the other hand, in Step S4, if it is determined that the
remaining calories Q are less than the total of the temperature
increasing calories QF, the reference calories QA, and the
correction amount QH, that is,
Q<QF+QA+QH=QLT
[0132] the cooling water heater 100 is used to increase the
temperature of the fuel cell 1 (Step S6).
[0133] In accordance with the alternative example 2, since the
variation in the start time period consumed calories due to
seasonal change may be accommodated by automatically correcting the
temperature increasing means select threshold QLT, it is possible
to achieve convenient and energy-saving cogeneration system capable
of inhibiting hot water from running out. In addition, the ambient
air temperature sensor 106 may be omitted.
[0134] While the monthly start time period consumed calorie time
lapse variation curve is obtained in real time, this may
alternatively be obtained from experiment, etc, and stored in the
storage 104 of the controller 201.
[0135] While the correction amount QH is calculated based on either
the ambient air temperature--start time period consumed calorie
characteristic or the monthly start time period consumed calorie
time lapse variation curve, this may alternatively be done based on
both of them. In that case, for example, correction amount QH' and
correction amount QH" are calculated based on both of them, and the
correction amount QH may be obtained by adding these correction
amounts QH' and QH" by weighting in a predetermined ratio.
[0136] (Embodiment 3)
[0137] FIG. 13 is a block diagram showing a construction of a fuel
cell cogeneration system according to a third embodiment of the
present invention. In FIG. 13, the same reference numerals as those
in FIG. 8 denote the same or corresponding parts which will not be
further described.
[0138] Turning to FIG. 13, in the third embodiment, a supplied hot
water temperature sensor 107 is attached to the pipe 33 through
which the hot eater stored in the tank 16 is supplied to consumers
and configured to detect temperature of supplied hot water. An
output of the supplied hot water sensor 107 is input to the
processor 105 of the controller 201. And, the processor 105 selects
temperature increasing means considering the detected temperature
of the supplied hot water. The other configuration is identical to
that of the second embodiment.
[0139] Subsequently, an operation of the above constructed
cogeneration system will be described.
[0140] FIG. 14 is a flowchart showing an operation to select a
temperature increasing means of the fuel cell cogeneration system
in FIG. 13. In FIG. 14, the same reference numerals as those in
FIG. 9 denote the same or corresponding steps which will not be
further described.
[0141] Turning to FIG. 14, in the third embodiment, the processor
105 calculates correction amount QH based on the ambient air
temperature in Step S15, and then in Step S16, calculates a
correction coefficient Kh considering that the hot water may run
out. Specifically, the signal indicating the detected temperature
is input from the sensor 107 to the processor 105, which converts
the signal into supplied hot water temperature to thereby obtain
it. A predetermined threshold of the temperature of the supplied
hot water is prestored in the storage 104. The predetermined
threshold is set to, for example, a normal temperature of city
water. The processor 105 reads out the threshold from the storage
104 and compares the threshold to the obtained supplied hot water
temperature. When the supplied hot water temperature is not higher
than the threshold, the processor 105 determines that the hot water
has run out. This is based on the fact that the temperature of the
supplied hot water decreases to the temperature of the city water
when the hot water is running out.
[0142] Then, in Step S16, the processor 105 calculates the
correction coefficient Kh by which the correction amount QH is to
be multiplied. The correction coefficient Kh is 1.0 or more, and
increases according to the number of times the hot water has run
out per predetermined time (e.g., per day).
[0143] In Step S4, the processor 105 determines whether or not the
remaining calories Q are not less than a total of the temperature
increasing calories QF, the reference calories QA, and a product of
the correction amount QH and the correction coefficient Kh.
[0144] If it is determined that the remaining calories Q are not
less than the total of the temperature increasing calories QF, the
reference calories QA, and the product of the correction amount QH
and the correction coefficient Kh, that is,
Q.gtoreq.QF+QA+QH.times.Kh=QLT
[0145] the remaining calories Q are consumed to increase the
temperature of the fuel cell 1 (Step S5).
[0146] On the other hand, in Step S4, if it is determined that the
remaining calories Q are less than the total of the temperature
increasing calories QF, the reference calories QA, and the product
of the correction amount QH and the correction coefficient Kh, that
is,
Q<QF+QA+QH.times.Kh=QLT
[0147] the cooling water heater 100 is used to increase the
temperature of the fuel cell 1 (Step S6).
[0148] As should be appreciated from the foregoing, in the third
embodiment, if the hot water should run out due to an increase in
calories consumed by consumers, the cogeneration system is
controlled to accommodate such variation by automatically
increasing the temperature increasing means select threshold QLT.
Therefore, it is possible to achieve a convenient and energy-saving
cogeneration system which does not run out calories consumed by
consumers during start of the fuel cell 1.
[0149] It is obvious that the above described construction is
applicable to the alternative example 1 of the second embodiment in
the same manner as described above. In that case, the correction
amount QH calculated in the alternative example 1 of the second
embodiment may be multiplied by the correction coefficient Kh
obtained in Step S16, and in Step S4, it may be determined whether
or not the remaining calories Q are not less than the total of the
temperature increasing calories QF, the reference calories QA, and
the product of the correction amount QH and the correction
coefficient Kh.
[0150] (Embodiment 4)
[0151] In the fourth embodiment, the alternative example 1 of the
first embodiment is altered. Hardware of the fuel cell cogeneration
system of the fourth embodiment is configured as in the fuel cell
cogeneration system of the second embodiment in FIG. 8. That is,
the ambient air temperature sensor 106 is added to the construction
(FIG. 1) of the hardware of the fuel cell cogeneration system of
the alternative example 1 of the first embodiment. And, the
processor 105 of the controller 201 selects the temperature
increasing means considering the ambient air temperature and the
stored hot water temperature. The other configuration is identical
to that of the alternative example 1 of the first embodiment.
[0152] FIG. 15 is a flowchart showing an operation to select a
temperature increasing means in the cogeneration system of the
fourth embodiment in FIG. 15. In FIG. 15, the same reference
numerals as those denote the same or corresponding steps which will
not be further described.
[0153] Turning to FIGS. 8 and 15, in the fourth embodiment, the
processor 105 obtains the stored hot water temperature TW and the
fuel cell operating temperature TO in Step S11. Thereafter, in Step
S17, the processor 105 converts the signal indicating the detected
temperature which is input from the ambient air temperature sensor
106 into ambient air temperature to thereby obtain it.
[0154] In Step S4, the processor 105 determines whether or not the
remaining calories Q are not less than the temperature increasing
calories QF, and if it is determined that the remaining calories Q
are less than the temperature increasing calories QF in Step S4,
the cooling water heater 100 is used to increase the temperature of
the fuel cell 1 (Step S6), whereas when the remaining calories Q
are not less than the temperature increasing calories QF in Step
S4, the processor 105 advances to Step S12.
[0155] In Step S12, the processor 105 determines whether or not the
stored hot water temperature TW is not lower than the fuel cell
operating temperature TO. If it is determined that the stored hot
water temperature TW is not lower than the operating temperature
TO, the remaining calories Q are consumed to increase the
temperature of the fuel cell 1 (Step S5), whereas when the stored
hot water temperature TW is lower than the operating temperature TO
in Step S12, the processor 105 advances to Step S18.
[0156] In Step S18, the processor 105 determines whether or not the
stored hot water temperature TW is not lower than the ambient air
temperature TA. If it is determined that the stored hot water
temperature TW is lower than the ambient air temperature TA, the
cooling water heater 100 is used to increase the temperature of the
fuel cell 1. On the other hand, if it is determined that the stored
hot water temperature TW is not lower than the ambient air
temperature TA, both of (or combination of) the remaining calories
Q and the cooling water heater 100 are used to increase the
temperature of the fuel cell 1. In that case, for example, the
processor 105 first increases the temperature of the fuel cell 1
using the remaining calories Q, and when the stack temperature
detected by the stack temperature sensor 202 becomes near the
stored hot water temperature TW, the processor 105 stops using the
remaining calories Q to increase the temperature of the fuel cell
1. Thereafter, the processor 105 increases the temperature of the
fuel cell 1 using the cooling water heater 100.
[0157] (Embodiment 5)
[0158] In a fifth embodiment of the present invention, the
operation to increase the temperature of the fuel cell 1 of the
first to third embodiments is altered as described below.
[0159] More specifically, both of the remaining calories Q and the
cooling water heater 1 are used to increase the temperature of fuel
cell 1 in Step S5 of the operation to select the temperature
increasing means of the first to third embodiments. And, the former
is mainly employed rather than the latter (a ratio of use the
former to the use of the latter is set higher). In addition, in
Step S6, both of the cooling water heater 100 and the remaining
calories Q are used to increase the temperature of the fuel cell 1.
And, the former is mainly employed rather than the latter (a ratio
of use the former to the use of the latter is set higher). This
ratio is determined based on time allocation or flow rate
allocation of the cooling water.
[0160] Turning to FIGS. 1, 8 and 13, if this ratio is determined
based on the time allocation, the temperature of the fuel cell 1 is
increased while switching the use of the remaining calories Q and
the use of the cooling water heater 100 so that the remaining
calories Q and the cooling water heater 100 are respectively used
for time periods according to this ratio.
[0161] On the other hand, if this ratio is determined based on the
flow rate allocation of the cooling water, the flow rate control
valve 13 and the flow rate control valve 14 are opened
simultaneously and their open degrees are adjusted so that the
cooling water flows through these valves 13 and 14 at flow rates
according to this predetermined ratio. And, the cooling water pump
9 and the cooling water heater 10 are operated and the pump 20 is
operated, and the circulating direction switch means 17 is
controlled so that the hot water circulates in the B direction.
[0162] In accordance with this configuration, the effects produced
by the first to third embodiments are also substantially obtained
in the fourth embodiment. Nonetheless, if the cooling water heater
100 is used when only the remaining calories Q should be used to
start the fuel cell 1 in the first to third embodiments, energy
efficiency of the cogeneration system is correspondingly reduced.
On the other hand, the remaining calories Q are used when only the
cooling water heater 100 should be used to start the fuel cell 1 in
the first to third embodiments, calories (e.g., amount of supplied
hot water) capable of being consumed during the start time period
tA are correspondingly reduced.
[0163] While the remaining calorie detector 101 is constituted by a
plurality of temperature sensors 101A, 101B, and 101C attached to
the surface of the tank 16 to be vertically spaced apart from one
another in the first to fifth embodiments, this may alternatively
be, as shown in FIGS. 1, 8 and 13, constituted by a heat exchanger
outlet temperature sensor 18 and a heat exchanger inlet temperature
sensor 19 respectively attached to the outlet and the inlet of the
heat exchanger 12 (in the flow direction A of hot water), and flow
rate meters respectively attached to the pipes 15a and 15b, and the
processor 105 may calculate heat recovery calories from the product
of difference between temperatures detected by the sensors 18 and
19 and the flow rates of the hot water flowing through the pipes
15a and 15b which are measured by the flow rate meters, and may
subtract the consumed calories E from the heat recovery
calories.
[0164] While the recovered heat is used for hot water supply in the
first to fifth embodiments, the present invention is also
applicable to a case where the recovered heat is used or air
conditioning or drying, and in that case, the same effects are
obtained.
[0165] While the tank 16 is layered hotwater tank in the first to
fifth embodiments, other types may be employed.
[0166] While the antifreezing fluid and the water are used as the
internal heat transfer medium and the external heat transfer
medium, respectively, in the first to fifth embodiments, other heat
transfer media may alternatively be used.
[0167] While the controller 201 is configured to control the
operation of the whole fuel cell cogeneration system and the
operation to select the temperature increasing means in the first
to fifth embodiments, a plurality of controllers may alternatively
be arranged to correspond to a plurality of desired components in
the fuel cell cogeneration system, and may operate in cooperation
with one another. So, as used herein, the controller refers to a
single controller and a group of a plurality of controllers
configured to operate in cooperation with one another.
[0168] While the controller 201 contains the storage 104
constituted by the internal memory as the storage means in the
first to fifth embodiments, data storage medium and data storage
medium driver capable of writing and reading out data to and from
the data storage medium may alternatively be used as the storage
means.
[0169] Numerous modifications and alternative embodiments of the
invention will be apparent to those skilled in the art in the light
of the foregoing description. Accordingly, the description is to be
construed as illustrative only, and is provided for the purpose of
teaching those skilled in the art the best mode of carrying out the
invention. The details of the structure and/or function may be
varied substantially without departing from the spirit of the
invention.
* * * * *