JP2001193987A - Heat storage apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively use cold heat stored in a heat storage section 3 in a heat storage apparatus wherein in a heat storage time zone cold heat applied to brine in a brine circuit 1 with a chiller is stored in the heat storage section 3, while in an air conditioning time zone a room is cooled with cold heat of the chiller 2 and the heat storage section 3. SOLUTION: On the basis of a heat storage amount of a heat storage section 3 detected by a water level sensor 13 upon finishing of an air conditioning time zone, excess judgement means 31 and deficiency judgement means 34 judge whether or not the heat storage amount is excessive. In contrast, the heat storage amount is excessive, heat storage full use means 32 assembles an operation in a heat storage full use direction to an operation pattern in a next day air conditioning time zone, while, when the heat storage amount is insufficient, heat storage preserve means 35 arranges an operation in a heat storage preserve direction to an operation pattern in a next day air conditioning time zone.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat storage device such as an ice storage device, and more particularly to a measure for using up heat such as cold generated and stored in a non-use time period such as nighttime in a use time period such as daytime.

[0002]

2. Description of the Related Art For example, during the night when electric power rates are low, a heat medium in a heat medium circuit is cooled by a heat source, ice is made in a heat storage unit by the heat medium, and cold heat is stored.
BACKGROUND ART Ice heat storage devices that perform daytime cooling with a high electricity rate are widely known.

[0003]

However, the conventional ice thermal storage device has a problem that it is actually difficult to efficiently use the ice generated at night in the daytime.

[0004] The present invention has been made in view of the above points, and a main object of the present invention is to gradually change the operation pattern of the next day's air conditioning time zone based on the remaining heat storage at the end of the air conditioning time zone. Is to make it possible to efficiently use the heat such as cold generated and stored during the heat storage time zone during the air conditioning time zone.

[0005]

In order to achieve the above object, according to the present invention, when the amount of stored heat is excessive, the operation pattern of the next use time zone is changed from the end time of the use time to the start time. The operation in the direction of decreasing the heat storage amount is gradually increased toward.

Specifically, according to the first aspect of the present invention, as schematically shown in FIG. 1, a heat medium circuit (1) for circulating a heat medium, a heat medium and a heat medium A heat source (2) for applying heat to the heat medium in the circuit (1), and heat received and stored from the heat medium in the heat medium circuit (1);
A heat storage unit (3) for applying the stored heat to the heat medium; and a use-side heat exchanger (4) for extracting heat from the heat medium in the heat medium circuit (1) for use. When the heat medium in the heat medium circuit (1) is not used during a non-use time period, the heat source (2) applies heat to the heat medium in the heat medium circuit (1) and stores the heat of the heat medium. While the operation is performed based on the operation pattern based on the heat storage operation stored in the section (3), when the heat medium of the heat medium in the heat medium circuit (1) is used during a use time period, the heat source (2) is used. An operation pattern based on a standard operation in which heat is applied to the heat medium in the heat medium circuit (1) and the heat stored in the heat storage section (3) is applied to the heat medium in the heat medium circuit (1). The premise is a heat storage device that is operated based on the above.

[0007] A heat storage amount detecting means (13) for detecting the heat storage amount of the heat storage section (3), and a heat storage remaining amount which is the heat storage amount detected by the heat storage amount detecting means (13) at the end of the use time zone. Determining means (31) for determining whether or not is excessive, and when it is determined by the excess determining means (31) that the remaining amount of heat storage is excessive, the operation pattern in the next use time zone includes: The heat storage depletion means (3) which incorporates operation in the heat depletion direction in which the heat stored in the heat storage unit (3) is depleted.
2).

In the above configuration, during the non-use time period, the heat storage device is operated based on an operation pattern based on the heat storage operation. In the heat storage operation, heat is applied to the heat medium in the heat medium circuit (1) by the heat source (2), while the heat of the heat medium is stored in the heat storage unit (3).
Then, during the use time period, the heat storage device operates based on an operation pattern based on the standard operation. In the standard operation, heat is applied to the heat medium in the heat medium circuit (1) by the heat source (2), and the heat stored in the heat storage section (3) is transferred to the heat medium in the heat medium circuit (1). And the heat of the heat medium is taken out and used by the use side heat exchanger (4). On the other hand, the heat storage amount of the heat storage unit is detected by the heat storage amount detecting means. If the amount of heat extracted from the use-side heat exchanger (4) is smaller than the amount of heat stored in the heat storage unit (3), the heat is stored in the heat storage unit (3) at the end of the use time period. The heat will remain unused.

At this time, at the end of the use time period, the remaining heat storage amount detected by the heat storage amount detecting means (13) is judged by the excess judging means (31) whether or not it is excessive. When the excess determination means (31) determines that the heat is excessive, the heat storage depletion means (32) sets the heat storage unit (3) in the operation pattern of the next use time zone.
Operation in the direction of using up the heat stored by the vehicle will be incorporated. Therefore, at the end of the next use time zone, the heat storage remaining amount of the heat storage unit (3) decreases by the amount of the above-mentioned operation, and
As a result, the heat stored in the heat storage unit (3) during the non-use time zone is efficiently used.

According to a second aspect of the present invention, in the first aspect of the present invention, the excess determination means (31) is excessive when the remaining amount of heat storage is within a predetermined range having a lower limit and an upper limit. Is determined.

In the above configuration, when the excess storage means determines at the end of the use time zone whether or not the remaining heat storage amount detected by the heat storage amount detection means is excessive, When the heat storage remaining amount is within a predetermined range, it is determined that the heat storage amount is excessive. At this time, the above range has a lower limit and an upper limit. Therefore, it is determined that the heat storage remaining amount is excessive when the remaining heat storage amount is equal to or more than the lower limit value. It will be performed properly. On the other hand, it is determined that the heat storage remaining amount is excessive when the remaining heat amount is equal to or less than the upper limit value. For example, when the heat storage remaining amount is not actually used during the set use time zone, or when the load is extremely small. Even when there is an exceptionally large amount of heat storage such as when there is a use time zone, it is possible to appropriately determine whether or not the heat storage amount is excessive without being affected.

According to a third aspect of the present invention, in the first to third aspects of the present invention, the heat storage use-up means (32) is determined by the excess determination means (31) at the end of each use time period to be determined to be excessive. Then, it is assumed that the operation in the heat storage use-out direction is incorporated by a predetermined unit time from the end time of the next use time zone to the start time of the use time zone.

In the above configuration, each time the excess time determining means (31) determines that there is an excess at the end of each use time period, the heat storage use-up means (32) causes the heat storage to be performed in the operation pattern of the next use time period. When the operation in the exhaustion direction is incorporated, the operation in the heat storage exhaustion direction is incorporated for a predetermined unit time. In other words, the heat storage use-up means (32) gradually increases the ratio of the operation in the heat storage use-out direction to the operation pattern in each use time zone. Therefore, a situation in which the ratio of the operation in the heat storage exhaustion direction to the operation pattern in the next use time zone sharply increases and conversely the heat storage amount becomes insufficient becomes unlikely to occur.

[0014] The operation in the heat storage use-up direction is incorporated from the end time of the next use time zone to the start time of the use time zone. Accordingly, the operation based on the predetermined operation pattern is reliably performed from the start time of the next use time zone to the time when the operation in the heat storage use direction starts.

According to a fourth aspect of the present invention, when the heat storage amount detected by the heat storage amount detecting means (13) at the end of the use time period is 0, the heat storage section (3 And (3) calculating whether or not the heat storage amount of the heat storage section (3) is insufficient based on the shortage calculated by the shortage calculation means (33). Shortage determining means (34) for determining whether or not the shortage determination means (34) determines that there is a shortage.
And a heat storage means (35) for incorporating operation in a heat storage preserving direction for preserving the heat stored.

In the above configuration, if the actual load during the next use time period unexpectedly increases and the heat storage amount becomes insufficient, the heat storage amount detection means is terminated at the end of the use time period. According to (13), it is detected that the heat storage amount is 0. At this time, the shortage amount calculating means (33) calculates the shortage amount of the heat storage amount of the heat storage section (3), and based on the shortage amount, the shortage determination means (34) determines the heat storage amount of the heat storage section (3). It is determined whether the amount is insufficient. Then, when it is determined that the operation is insufficient, the heat storage preserving means (35) incorporates the operation in the heat storage preservation direction, which is the operation in the direction opposite to the heat storage exhaustion direction, into the operation pattern in the next use time zone. . Therefore, at the end of the next use time zone, the shortage of the heat storage amount of the heat storage unit (3) is reduced by the amount of the operation incorporated, and the heat storage unit (3)
The increase in the load on the heat source (2) due to the shortage of the heat storage amount can be suppressed.

According to a fifth aspect of the present invention, in the fourth aspect of the present invention, the shortage amount calculating means (33) is adapted to operate within a usage time period from the time when the heat storage amount detected by the heat storage amount detecting means (13) becomes zero. It is assumed that the shortage amount is calculated based on the amount of heat required until the time when the calculation is completed.

In the above configuration, the heat storage amount detected by the heat storage amount detecting means (13) at the end of the use time period is zero.
In this case, the shortage amount calculating means (33) performs the operation from the time when the heat storage amount detected by the heat storage amount detecting means (13) becomes 0 in the use time period to the time when the use time period ends. The shortage is calculated based on the amount of heat required during the period. Therefore, the operation of the shortage amount calculating means (33) in the fourth aspect of the present invention is specifically performed.

According to the sixth aspect of the present invention, the fourth and fifth aspects are described.
In the invention, the shortage determination means (34) determines that the shortage amount is
When within a predetermined range having a lower limit and an upper limit,
It is assumed that the configuration is such that it is determined to be insufficient.

In the above arrangement, the shortage judging means (3
When it is determined in 4) whether or not the heat storage amount of the heat storage unit (3) is insufficient, it is determined that the heat storage amount is insufficient when the shortage is within a predetermined range. At this time, the above range has a lower limit and an upper limit. Therefore, when the deficiency is equal to or more than the lower limit, it is determined that the deficiency is insufficient.
The determination as to whether or not the heat storage amount is insufficient is appropriately performed without being affected by the variation in load for each use time zone. On the other hand, when the shortage amount is less than the upper limit value, it is determined to be insufficient.For example, when sufficient heat storage is not performed for some reason during a non-use time period, or when the use time period is Even when the shortage amount is exceptionally large, such as in an extremely large peculiar time zone, it is possible to appropriately determine whether the shortage amount is insufficient without being affected by the shortage amount.

According to a seventh aspect of the present invention, in the above fourth to sixth aspects, the heat storage means (35) is determined by the shortage determining means (34) to be insufficient at the end of each use time zone. In addition, it is assumed that the operation in the heat storage preserving direction is incorporated for each predetermined unit time from the start time of the next use time zone to the scheduled end time of the use time zone.

In the above configuration, each time the shortage judging means (34) determines that the operation is excessive at the end of each use time zone, the operation in the heat storage preserving direction is incorporated by the heat storage preserving means (35). The operation in the heat storage preserving direction is incorporated for a predetermined unit time. In other words, the heat storage conserving means (35) gradually increases the ratio of the operation in the heat storage preserving direction to the operation pattern for each use time zone. Therefore,
A situation in which the ratio of the operation in the heat storage preserving direction to the operation pattern in the next use time zone sharply increases and conversely the heat storage amount becomes less likely to occur.

The operation in the heat storage preserving direction is incorporated from the start time of the next use time zone to the end time of the use time zone. Therefore, the operation based on the predetermined operation pattern is reliably performed from the time when the operation in the heat storage preservation direction ends to the end time of the use time zone.

According to an eighth aspect of the present invention, in the first to seventh aspects, the heat source (2) generates cold heat and applies the generated cold heat to the heat medium in the heat medium circuit (1). The heat storage unit (3) receives and stores cold heat from the heat medium in the heat medium circuit (1), and applies the cold heat to the heat medium, and uses the heat-side heat exchanger (4).
Is assumed to be used for extracting cold heat from the heat medium in the heat medium circuit (1) and cooling it.

In the above configuration, in the heat storage device, during a non-use time period, the heat source (2) applies cold to the heat medium in the heat medium circuit (1) and cools the heat medium to the heat storage section (3). The operation based on the operation pattern based on the heat storage operation that stores ice water in (1) is performed. On the other hand, during the use time zone, the heat source (2) applies cold heat to the heat medium in the heat medium circuit (1), and the heat stored in the heat storage section (3) is transferred to the heat medium in the heat medium circuit (1). The operation based on the operation pattern based on the standard operation given to the medium is performed.
Then, in the use side heat exchanger (4), cold heat is extracted from the heat medium in the heat medium circuit (1) and is used for, for example, indoor cooling. Therefore, the operation of the heat storage device according to the first to seventh aspects of the present invention is specifically performed.

[0026]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 schematically shows the entire configuration of a heat storage device according to an embodiment of the present invention. This heat storage device is used by being connected to an air conditioner (20) for cooling and heating the room.

The heat storage device is a brine circuit (1) as a heat medium circuit for circulating brine as a heat medium.
And a heat source that is provided on the brine circuit (1) to generate cold heat in the cooling mode, and to generate heat in the heating mode, and to apply the generated heat to the brine in the brine circuit (1). A chiller (2), and a heat storage unit provided on the brine circuit (1) for receiving and storing heat from the brine in the brine circuit (1), and for applying the stored heat to the brine ( 3) and a use-side heat exchanger (4) provided on the brine circuit (1) for extracting heat from the brine in the brine circuit (1) and using the same.

Specifically, the brine circuit (1) includes:
It has a main pipe that annularly connects the chiller (2), the heat storage section (3), and the use side heat exchanger (4), and the main pipe has first and second two bypass pipes ( 5),
(6) is connected. A brine pump (7) for circulating brine in the brine circuit (1) in a direction indicated by an arrow in FIG. 2 is provided between the use side heat exchanger (4) and the chiller (2) on the main pipe. Is provided.

The first bypass pipe (5) is disposed near the heat storage section (3), and has one end connected to the inlet side of the heat storage section (3) in the main pipe, and the other end connected to the main pipe. The main pipe is connected to the outlet side of the heat storage section (3).
The connection between the other end of the first bypass pipe (5) and the outlet of the heat storage section (3) in the main pipe has a first bypass pipe (5) and a heat storage section downstream of the connection. A first three-way valve (5a) for selectively communicating the part (3) is provided. When the first three-way valve (5a) is switched to the heat storage unit (3), the brine in the brine circuit (1) circulates through the heat storage unit (3), while the first bypass pipe ( By switching to the side of 5), circulation is performed around the heat storage section (3).

The second bypass pipe (6) is disposed near the use side heat exchanger (4), and has one end connected to the outlet side of the first three-way valve (5a) in the main pipe and the use side heat exchanger. The other end is connected between the outlet side of the use side heat exchanger (4) and the inlet side of the brine pump (7) in the main pipe while being connected between the inlet side of the exchanger (4). ing. In addition, the connection between the other end of the second bypass pipe (6) and the outlet side of the use side heat exchanger (4) in the main pipe has a second bypass pipe with respect to the downstream side of the connection. A second three-way valve (6a) is provided for selectively communicating (6) and the use side heat exchanger (4). When the second three-way valve (6a) is switched to the use side heat exchanger (4), the brine in the brine circuit (1) circulates through the use side heat exchanger (4). By switching to the side of the second bypass pipe (6), the circulation bypasses the use side heat exchanger (4).

Although the illustration of the chiller (2) is omitted,
A compressor (8) for compressing the refrigerant, an expansion section for expanding the refrigerant, and two heat exchangers for transferring cold or warm heat between the refrigerant and the refrigerant circuit on the refrigerant circuit in which the refrigerant is circulated. A plurality of pumps for circulating the refrigerant, and a plurality of heat exchangers for selectively switching the two heat exchangers between a function as a condenser for releasing heat from the refrigerant and a function as an evaporator for absorbing heat from the refrigerant. It consists of a bypass pipe and a switching valve. The main pipe of the brine circuit (1) is connected to one of the two heat exchangers, and in the cooling mode, one of the heat exchangers functions as a condenser and is operated as a condenser. Heat is applied to the brine in the circuit (1), and in the heating mode, it functions as an evaporator to apply cold to the brine.

The heat storage section (3) includes a heat storage tank (9) for storing water as a heat storage medium, and the heat storage tank (9).
A heat transfer pipe (10), which is arranged in the inside and is connected at both ends to a main pipe of the brine circuit (1), and a heat storage tank (9)
It has an air supply pipe (11) arranged at the bottom of the inside, and an air pump (12) for feeding air to the air supply pipe (11). When the brine in the brine circuit (1) passes through the heat transfer pipe (10), cold or hot heat is transferred to and from the water in the heat storage tank (9). By supplying air from the air supply pipe (11) into the heat storage tank (9) by the operation of the air pump (12), the water in the heat storage tank (9) is agitated. The heat storage tank (9) has a water level sensor (13) as a heat storage amount detecting means for detecting a water level in the heat storage tank (9), and a temperature (not shown) for detecting a water temperature in the heat storage tank (9). Sensor (eg, thermistor)
Is provided, for example, when storing cold heat,
Utilizing the fact that water changes in volume with a phase change, the amount of cold heat stored is detected by the water level in the heat storage tank (9) detected by the water level sensor (13).

On the other hand, the air conditioner (20) includes a circulation circuit (21) in which water as a heat medium is circulated so as to be circulated.
An indoor heat exchanger (22) provided on the circulation circuit (21) for extracting heat from water in the circulation circuit (21) and supplying cooling or heating air to the room.
And a circulation pump (23) provided on the circulation circuit (21) to circulate water in the circulation circuit (21). The outlet side of the circulation pump (23) and the inlet side of the indoor heat exchanger (22) in the circulation circuit (21) are connected to the use side heat exchanger (4) of the heat storage device.

The brine circuit of the heat storage device (1)
A temperature sensor (14) for detecting a brine temperature at an outlet side of the chiller (2) is provided on an outlet side of the chiller (2) in the main pipe of the first circuit in the main pipe of the brine circuit (1). Between the outlet side of the three-way valve (5a) and the inlet side of the use side heat exchanger (4), the use side heat exchanger (4)
A temperature sensor (15) for detecting a brine temperature, which is the temperature of the heat taken out by the device, is provided. Further, at the outlet side of the use side heat exchanger (4) in the circulation circuit (21) of the air conditioner (20), the heat of the brine is given by the use side heat exchanger (4), so that the indoor heat Temperature sensor (1) for detecting the temperature of the feed water sent to the exchanger (22)
6) is provided. And these three temperature sensors (14) to (16), the brine pump (7), the air pump (12), the first and second three-way valves (5a),
(6a) and the use side heat exchanger (4) are assembled as one unit. The detection signals of the three temperature sensors (14) to (16) are input to a controller (17) described below together with the water level sensor (13) and the like.

The controller (17) receives signals from a water level sensor (13), temperature sensors (14) to (16), and performs various controls based on a preset program. I have. Specifically, the start and stop of the brine pump (7), the chiller (2) and the air pump (12), the capacity control of the chiller (2), the first and second
The switching control of the three-way valves (5a) and (6a) is performed. Also,
The removal temperature automatic control of the first three-way valve (5a) is performed based on a detection signal of a temperature sensor (14) for detecting the removal temperature of the brine passing through the first three-way valve (5a). The automatic control of the feed water temperature of the second three-way valve (6a) is performed by detecting the temperature sensor (16) located on the outlet side of the use side heat exchanger (4) on the circulation circuit (21) of the air conditioner (20). This is performed based on the signal.

In the above heat storage device, basically, in the heat storage time period as a non-use time period in which the use side heat exchanger (4) is not used, the chiller (2) causes the inside of the brine circuit (1). The operation is performed based on an operation pattern based on a heat storage operation in which heat is applied to the brine and the heat of the brine is stored in the heat storage unit (3), while the usage of the usage-side heat exchanger (4) is performed. In the air conditioning time zone (for example, the time zone from 8:00 am to 6:00 pm) as a time zone, heat is applied to the brine in the brine circuit (1) by the chiller (2) and the heat is stored in the heat storage unit (3). An operation based on an operation pattern based on a standard operation for applying the stored heat to the brine in the brine circuit (1) is performed.

Here, the main operation control of the heat storage device configured as described above will be described with reference to the flowchart of FIG.

When the heat storage device is turned on, it is determined in step 1 whether or not the system is operating.
When the determination is YES, the process shifts to step 2 to determine whether the mode is the cooling mode. If the determination in step 2 is YES, the process proceeds to step 3 and enters the cooling mode. On the other hand, the determination in step 2 is N
If the answer is O, the routine goes to Step 5 and enters the heating mode.

In step 3, it is determined whether or not the current time is in the heat storage time zone. Then, if the determination is YES, the process shifts to step 10 to execute a subroutine of "ice making operation". On the other hand, if the determination is NO, the process shifts to step 4 to determine whether or not it is in the air conditioning time zone.
In the case of ES, the process proceeds to step 11 to execute a "cooling operation" subroutine.

In step 5 described above, it is determined whether or not the current time is in the heat storage time zone. If the determination is YES, the process proceeds to step 12 to execute a subroutine of "temperature storage operation". On the other hand, if the determination is NO, the process proceeds to step 6, where it is determined whether or not it is in the air conditioning time zone.
In the case of, the routine proceeds to step 13, where a subroutine "heating operation" is executed. Step 1 and Step 4
And in step 6, when the determination is NO,
Return to start.

Next, basic control of the ice making operation, the cooling operation, the warm storage operation and the heating operation will be described in order.

In the ice making operation, the chiller (2) applies cold heat to the brine, and switches the first three-way valve (5a) to the heat storage section (3). In addition, the second three-way valve (6
Regarding a), when the air conditioner (20) is operating, the air conditioner is switched to the second bypass pipe (6), while when the air conditioner (20) is not operating,
Automatic control of feed water temperature is performed based on the water temperature in the circulation circuit (21). When the ice making is completed, the chiller (2)
Is stopped, and the routine goes to Step 1 of the flowchart.

In the cooling operation, the cooling water of the second three-way valve (6a) is automatically controlled while mainly adding the cooling heat of the chiller (2) to the cooling heat of the heat storage section (3). At this time, when the peak cut command is input, the chiller (2) is stopped. For the first three-way valve (5a), while ice is present in the heat storage unit (3), the extraction temperature automatic control based on the extraction temperature of the brine is performed, and the air pump (1) is operated.
2) is actuated, while the first three-way valve (5
Switch a) to the side of the first bypass pipe (5) and stop the air pump (12).

In the warm storage operation, heat is applied to the brine by the chiller (2), and the first three-way valve (5a) is switched to the heat storage section (3). In addition, the second three-way valve (6
Regarding a), when the air conditioner (20) is operating, the air conditioner is switched to the second bypass pipe (6), while when the air conditioner (20) is not operating, the feed water temperature is automatically controlled. Then, when the heat storage is completed, the chiller (2) is stopped, and the process proceeds to step 1 of the above-mentioned flowchart.

In the heating operation, the temperature of the heat storage section (3) is mainly controlled, and the temperature of the second three-way valve (6a) is automatically controlled while appropriately adding the temperature of the chiller (2). The first three-way valve (5a) switches to the heat storage unit (3) when the air conditioner (20) starts heating, and performs automatic extraction temperature control after the heating start. When the heat storage is exhausted, the first three-way valve (5a) is switched to the first bypass pipe (5).

In this embodiment, as shown in FIG. 1, the controller (17) of the heat storage device includes a heat storage amount detecting means (13) comprising a water level sensor at the end of a daily air conditioning period in the cooling mode. Excessive judging means (31) for judging whether or not the heat storage amount, which is the heat storage amount detected by the water level sensor (hereinafter, referred to as a water level sensor), is excessive. When it is determined that there is, in the operation pattern of the air conditioning time zone of the next day, there is provided a heat storage exhaustion means (32) for incorporating an operation in the heat storage exhaustion direction in which the heat stored in the heat storage unit (3) is exhausted.

More specifically, the excess determination means (31)
Indicates that the remaining heat storage amount is lower than the lower limit value (for example, 5 to 10 of the total heat storage amount).
%) And an upper limit (for example, about 40 to 50%), it is determined to be excessive. In addition, the heat storage exhaustion means (3)
2) The excess determination means (3) at the end of the daily air conditioning time period.
Each time it is determined to be excessive according to 1), the operation in the heat storage exhaustion direction is performed for a predetermined unit time (for example, 1) from the end time of the air conditioning time zone to the start time of the air conditioning time zone on the next day.
Time).

Further, the controller (17) includes:
When the heat storage amount detected by the water level sensor (13) at the end of the air conditioning time period is 0, a shortage calculation means (33) for calculating the shortage of the heat storage in the heat storage section (3); An insufficiency determining means (34) for determining whether or not the heat storage amount of the heat storage section (3) is insufficient based on the insufficiency calculated by the calculating means (33); When it is determined that there is, in the operation pattern of the air conditioning time zone of the next day, a heat storage preserving means (35) that incorporates a heat storage preservation operation that preserves the heat stored by the heat storage unit (3).
Are provided.

Specifically, the shortage amount calculating means (33)
Calculates the shortage based on the amount of heat required from the time when the heat storage amount detected by the water level sensor (13) becomes 0 to the time when the air conditioning time period ends. . Further, the shortage determination means (34) determines that the shortage amount is within a predetermined range having a lower limit (for example, about 5 to 10%) and an upper limit (for example, about 40 to 50%). It has become.

Next, in the heat storage device configured as described above, with respect to the control for eliminating the excess or deficiency of the heat storage amount in the operation pattern during the air conditioning time period in the cooling mode, the chiller (2) is stopped and the heat storage unit ( The case 3) where the peak cut operation is performed only by the cold heat and the case where the peak cut operation is not performed will be described separately.

In the case where the peak cut operation is not performed, in this case, an operation pattern based on the standard operation is performed as the base pattern over the entire air-conditioning time period, as schematically shown in FIG. Will be In this standard operation, the chiller (2) applies cold to the brine in the brine circuit (1), and the cold stored in the heat storage unit (3) during the heat storage time zone is supplied to the brine in the brine circuit (1). Is given to That is, a certain amount of cold heat is extracted from the heat storage unit (3), and the remaining cold heat and the cold heat corresponding to the load fluctuation are provided by the chiller (2).

At the end of the air conditioning time period based on the base pattern, the excess storage means (31) determines whether or not the remaining amount of heat storage detected by the water level sensor (13) is excessive. When it is determined that there is, in the operation pattern in the air conditioning time period of the next day, the heat storage use means (32) sets the first heat storage use operation as the operation in the heat storage use direction in which the heat stored in the heat storage unit (3) is used up. Driving is incorporated. The first heat storage exhaustion operation is to increase the brine temperature at the outlet side of the chiller (2) to a predetermined temperature (for example, a temperature higher by 1 ° C. than in the standard operation) for a predetermined time. (Eg, one hour). In addition, the first heat storage exhaustion operation is incorporated at a time immediately before the end time of the air conditioning time zone, as shown in FIG. That is, if the air conditioning time period is from 8:00 am to 6:00 pm,
From 10:00 to 5:00 pm, the standard operation will be performed, and the first heat storage depletion operation (shown as “discharge 1” or “heat storage depletion operation 1” in the figure) is 5:00 pm Only one hour between 6:00 and 6:00 pm.

At the end of the air conditioning time period of the next day, when the excess determination means (31) again determines that the air conditioner is excessive, the heat storage exhaustion means (32) changes the first day operation pattern to the operation pattern of the next day. The thermal storage run-out operation is integrated for another hour. That is, the standard operation is performed from 8:00 am to 4:00 pm, and is incorporated only for two hours from 4:00 pm to 6:00 pm.

In this manner, the time of the first heat storage exhaustion operation is incorporated for one hour each time the daily air conditioning time period ends, and the operation pattern of the air conditioning time period is only the first exhaustion operation. At the end of the air conditioning hours of the day,
When it is determined that the operation is still excessive, the second heat storage exhaustion operation (denoted as “use-out 2” or “heat-storage use-out operation 2” in FIG. 5) is performed for a predetermined time (for example, one hour). )
Only incorporated into driving patterns. In this second heat storage exhaustion operation, the operation of the chiller (2) is stopped and the heat storage unit (3)
And the cold heat is applied to the brine only by the heat storage of the air conditioner, and is incorporated into the time immediately before the end time of the air conditioning time zone, as in the case of the first heat storage exhaustion operation. That is, the first heat storage exhaustion operation is performed from 8:00 am to 5:00 pm, and the second heat storage exhaustion operation is performed from 5:00 pm to 6:00 pm.

Further, at the end of the air conditioning time period of the next day, when the excess determination means (31) again determines that the air conditioner is excessive, the heat storage exhaustion means (32) changes the second day operation pattern to the operation pattern of the next day. The thermal storage run-out operation is integrated for another hour. That is, as shown in FIG. 6, the first heat storage depletion operation is performed from 8:00 am to 4:00 pm, and is incorporated for only two hours from 4:00 pm to 6:00 pm.

In this way, when the time of the second heat storage exhaustion operation is incorporated for one hour at the end of each air conditioning time zone, the operation pattern of the air conditioning time zone is finally changed. Only the second heat storage use-up operation will be performed.

On the other hand, if the heat storage amount becomes insufficient, the water level sensor (13) detects that the heat storage amount is 0 at the end of the air conditioning time zone of the day. At this time, the shortage amount calculating means (33) calculates the shortage of the heat storage amount of the heat storage unit (3), and based on the shortage, the shortage determination means (34) determines the heat storage amount of the heat storage unit (3). Is determined to be insufficient. Then, when it is determined that the heat storage is insufficient, the heat storage preserving means (35) incorporates the operation in the heat storage preservation direction, which is the operation in the direction opposite to the heat storage exhaustion direction, into the operation pattern of the air conditioning time zone of the next day. .

Specifically, for example, when it is determined that the heat storage amount is insufficient at the end of the air-conditioning time period in which the operation pattern includes only the standard operation, as shown in FIG. In the figure, "conservation" or "heat storage preservation operation" is included in the operation pattern for a predetermined time (for example, one hour). In the heat storage-sparing operation, the brine temperature at the outlet side of the chiller (2) is reduced to a predetermined temperature (for example, a temperature lower by 2 ° C. than in the standard operation). In addition, the heat storage-sparing operation is included in the time immediately after the start time of the air conditioning time zone, contrary to the case of the first and second heat storage exhaustion operations. That is, the heat storage-sparing operation is incorporated only for one hour from 8:00 am to 9:00 am, and the standard operation is performed from 9:00 am to 6:00 pm.

At the end of the air conditioning time period of the next day, if the shortage judging means (34) again determines that the air conditioner is in shortage, the heat storage preserving means (35) applies the heat storage preservation to the operation pattern of the next day. Driving is integrated for another hour. That is, the heat storage-sparing operation is incorporated for only 2 hours from 8:00 am to 10:00 am, and the standard operation is performed from 10:00 am to 6:00 pm.

As described above, when the time of the heat storage-sparing operation is incorporated for each hour at the end of the daily air-conditioning time zone, finally, the operation pattern of the air-conditioning time zone is limited to the heat storage-sparing operation only. However, if the amount of heat storage is still insufficient, it means that the capacity of the heat storage tank (9) of the heat storage unit (3) itself is insufficient.

When the amount of heat storage is insufficient due to the operation pattern in which the first heat storage use-up operation and the second heat storage use-up operation are incorporated, when the second heat storage use-up operation is incorporated in the operation pattern, Every time the shortage is determined, the second heat storage exhaustion operation is replaced with the first heat storage exhaustion operation for one hour from the start time to the end time of the air conditioning time zone. If the amount of heat is still insufficient even when only the first heat storage exhaustion operation is performed, the first heat storage exhaustion operation is switched to the standard operation for each hour from the start time to the end time of the air conditioning time zone every time the shortage is determined. It will be replaced. Conversely, when the amount of heat storage becomes excessive due to the operation pattern incorporating the heat storage-sparing operation, the heat storage-sparing operation is switched to the standard operation for each hour from the end time of the air-conditioning time zone to the start time every time the excess is determined. It will be replaced.

-When the peak cut operation is performed-In the peak cut operation, a predetermined time period (for example, from 1:00 pm to 4:00 pm) in the air conditioning time period of a day.
Done in In this peak cut operation, the chiller (2)
Is forcibly stopped, and indoor cooling air conditioning is performed only by the cold stored in the heat storage unit (3) during the heat storage time zone.

The driving base pattern in this case is shown in FIG.
As shown in (2), during the period from the start time of the air conditioning time zone to the start time of the peak cut operation (between 8:00 am and 1:00 pm), the above-described heat storage preservation operation is performed, and the peak cut operation is started. The standard operation is performed from the end time to the end time of the air conditioning time zone (from 4:00 pm to 6:00 pm).

At the end of the air-conditioning period in which the operation according to the base pattern is performed, the result of the determination whether the remaining heat storage amount detected by the water level sensor (13) is excessive by the excess determining means (31). When it is determined that the operation is excessive, first, the standard operation is incorporated into the base pattern in the air conditioning time period of the next day by the heat storage use means (32) as the operation in the heat storage use direction. In particular,
This standard operation is incorporated for a predetermined time (for example, one hour) from the end time of the air conditioning time zone to the start time, but in the case of the base pattern, the end time of the peak cut operation and the end time of the air conditioning operation Until the standard operation is already performed, the standard operation is incorporated into the time immediately before the start time of the peak cut operation as shown in FIG. That is, after the heat storage-sparing operation is performed from 8:00 am to 0:00 pm, the standard operation is performed from 0:00 pm to 1:00 pm, and from 1:00 pm to 4:00 pm After the peak cut operation is performed, the standard operation is performed again from 4:00 pm to 6:00 pm.

At the end of the air conditioning time period of the next day, when the excess determination means again determines that the air conditioner is excessive, the heat storage exhaustion means incorporates the standard operation for another hour into the operation pattern of the next day. . That is, after the heat storage-sparing operation is performed from 8:00 am to 11:00 am, the standard operation is performed at a time other than the peak cut operation time from 11:00 am to 6:00 pm.

In this manner, the standard operation is incorporated for each hour at the end of the daily air conditioning period, and the operation pattern during the air conditioning period is only the peak cut operation and the standard operation. At the end of the air-conditioning period, when it is determined that the operation is still excessive, the first heat storage exhaustion operation is incorporated into the time immediately before the end time of the air-conditioning period on the following day for one hour. That is, the standard operation is performed from 8:00 am to 5:00 pm excluding the time of the peak cut operation, and the first heat storage exhaustion operation is performed from 5:00 pm to 6:00 pm.

Further, when it is determined that the air conditioner is excessive at the end of the air conditioning time zone of the next day, the first heat storage exhaustion operation is performed in the operation pattern of the next day as shown in FIG.
Incorporated for another hour. That is, the standard operation is performed from 8:00 am to 1:00 pm, and the first heat storage exhaustion operation is performed from 4:00 pm to 6:00 pm when the peak cut operation ends.

As described above, the first heat storage exhaustion operation is incorporated at the end of each aerial time zone every day, and the air conditioning on the day when the operation pattern excluding the peak cut operation is only the first heat storage exhaustion operation is performed. At the end of the time period, if it is determined that the operation is still excessive, the second heat storage exhaustion operation is incorporated into the time immediately before the end time of the next day's air conditioning time period for one hour. That is, the first heat storage exhaustion operation is performed at times other than the peak cut operation between 8:00 am and 5:00 pm, and the second heat storage exhaustion operation is performed between 5:00 pm and 6:00 pm Becomes
After that, if the excess determination continues, the operation patterns are only the peak cut operation and the second heat storage exhaustion operation.

On the other hand, if the heat storage amount becomes insufficient, the water level sensor (13) detects that the heat storage amount is 0 at the end of the air conditioning time zone on that day. At this time, the shortage amount calculating means (33) calculates the shortage of the heat storage amount of the heat storage unit (3), and based on the shortage, the shortage determination means (34) determines the heat storage amount of the heat storage unit (3). Is determined to be insufficient. Then, when it is determined that the heat storage is insufficient, the heat storage preserving means (35) incorporates the operation in the heat storage preservation direction, which is the operation in the direction opposite to the heat storage exhaustion direction, into the operation pattern of the air conditioning time zone of the next day. .

Specifically, for example, when it is determined that the heat storage amount is insufficient at the end of the air conditioning time zone based on the base pattern, as shown in FIG. Incorporated in driving patterns instead of driving. That is, the one-hour standard operation immediately after the end of the cut operation is replaced with the heat storage-preserving operation. Therefore, the standard operation is performed only for one hour immediately before the end of the air conditioning time zone.

At the end of the air conditioning time period of the next day,
When it is determined to be insufficient, another hour of heat storage-sparing operation is incorporated. That is, except for the peak cut operation, the operation pattern in the air conditioning time zone is performed only by the heat storage preservation operation. If the heat storage amount is still insufficient, it means that the capacity of the heat storage tank (9) of the heat storage unit (3) itself is insufficient.

Therefore, according to the present embodiment, the cool heat given to the brine in the brine circuit (1) by the chiller (2) during the heat storage time zone is stored in the heat storage section (3), and the heat is stored in the air conditioning time zone. Sometimes, in a heat storage device configured to perform indoor cooling by cooling of the chiller (2) and the heat storage unit (3), the water level sensor (13) at the end of the air conditioning time zone.
The excess determination means (31) and the shortage determination means (34) determine the excess or deficiency of the heat storage amount based on the heat storage amount of the heat storage unit (3) detected by the above, and when the heat storage amount is excessive,
While the operation of the heat storage use direction is incorporated into the operation pattern of the air conditioning time zone of the next day by the heat storage use means (32),
When the heat storage amount is insufficient, the heat storage preserving means (35) incorporates the operation in the heat storage preserving direction into the operation pattern in the air conditioning time zone of the next day, so that the cold stored in the heat storage unit (3) is used efficiently. be able to.

Further, when the operation in the direction of using up the heat storage or in the direction of preserving the heat storage is incorporated, it is incorporated only for a predetermined unit time. By incorporating such an operation, conversely, the amount of heat storage becomes insufficient. It is possible to steadily eliminate the excess and deficiency of the heat storage amount without causing a situation of becoming excessive.

Further, when an excessive determination is made at each end of the air-conditioning time zone and the operation in the heat storage exhaustion direction is incorporated every day, the time from the end time of the air-conditioning time zone to the start time of the air-conditioning time zone is increased. On the other hand, when the operation is performed in the direction of the heat storage preservation every day when the shortage is determined at the end of the air conditioning time zone and the operation in the heat storage preserving direction is performed every day, the air conditioning time zone is started from the start time of the air conditioning time zone. In order to avoid the situation where the amount of heat stored is insufficient and air conditioning is hindered even if the amount of usage in the first half of the air conditioning time zone increases unexpectedly, as it is incorporated in the order of one hour toward the end time of On the other hand, even when the amount of use in the latter half of the air conditioning time zone unexpectedly decreases, it is possible to avoid the waste that a large amount of heat storage remains.

In the above-described embodiment, the operation in the heat storage exhaustion direction is performed by a predetermined unit time from the end time of the air-conditioning time zone toward the start time of the air-conditioning time zone each time the determination is excessive at the end of the air conditioning time zone. Incorporation is performed, but how many unit times are incorporated, and at what time during the air conditioning time zone, the time can be appropriately set according to the degree of the heat storage use direction and other conditions.

Further, in the above embodiment, every time when the shortage is determined at the end of the air conditioning time zone, the operation in the heat storage preserving direction is performed for a predetermined unit time from the start time of the air conditioning time zone toward the end time of the air conditioning time zone. Incorporation is performed, but how much time is to be incorporated and at what time during the air-conditioning time zone can be appropriately set according to the degree of heat storage preservation direction and other conditions.

In the above embodiment, the cooling operation in the cooling mode in which the heat storage section takes out the cold stored by the ice making operation is described. However, in the present invention, the heat storage section stores the cold heat by the hot storage operation. The present invention can also be applied to a heating operation in a heating mode in which heat is taken out.

Further, in the above embodiment, the case of the heat storage device capable of performing both the cooling mode and the heating mode has been described. However, the present invention can be applied to a heat storage device dedicated to the cooling mode.

[0080]

As described above, according to the first aspect of the present invention, the heat applied to the heat medium in the heat medium circuit by the heat source during the non-use time zone is stored in the heat storage unit, and the use time is reduced. In the heat storage device, the heat of the heat source and the heat storage unit is used for cooling and heating the room when the heat storage unit is in the zone, and based on the heat storage amount of the heat storage unit detected by the heat storage amount detection unit at the end of the use time zone, The determination means determines whether or not the heat storage amount is excessive, and when the heat storage amount is excessive, the heat storage use-out means incorporates the operation in the heat storage use-out direction into the operation pattern of the next use time zone, The heat stored in the heat storage unit can be used efficiently.

According to the second aspect of the present invention, the excess determination means is configured to determine the excess when the heat storage remaining amount is within the predetermined range having the lower limit value and the upper limit value.
The operation in the heat storage use direction can be appropriately incorporated without being influenced by the variation of the load on the user side or a unique environmental change in which the load on the user side extremely fluctuates.

According to the third aspect of the present invention, each time the excess storage means is judged to be excessive at the end of each use time zone, the heat storage use-up means is used from the end time of the next use time zone. As the system is configured to incorporate the operation in the heat storage exhaustion direction by a predetermined unit time toward the start time of the time zone, the amount of heat storage becomes insufficient due to an unexpected increase in the load during the first half of the usage time zone, which hinders use. The situation of coming can be avoided.

According to the fourth aspect of the present invention, the heat storage amount detected by the heat storage amount detecting means at the end of the use time period is zero.
In this case, the shortage amount calculating means for calculating the shortage amount of the heat storage amount of the heat storage unit, and whether the heat storage amount of the heat storage unit is insufficient based on the shortage amount calculated by the shortage amount calculation means is determined. Shortage determination means to perform, and when the shortage determination means determines that there is a shortage, a heat storage preservation means for incorporating operation in a heat storage preservation direction for preserving heat stored in the heat storage unit in an operation pattern of the next use time zone. So that
Combined with the effect of the first aspect of the present invention, the amount of heat storage can be optimized.

According to the fifth aspect of the present invention, the shortage amount calculating means is required between the time when the heat storage amount detected by the heat storage amount detecting means becomes 0 and the time when the use time period ends. Since the shortage amount is calculated based on the heat amount, the shortage amount of the heat storage amount can be appropriately obtained, and thus the effect of the fifth aspect can be specifically obtained.

According to the sixth aspect of the present invention, the shortage judging means is configured to judge the shortage when there is a shortage within a predetermined range having a lower limit and an upper limit. The operation in the heat storage preserving direction can be appropriately incorporated without being influenced by load variations or unusual environmental changes in which the load on the user side fluctuates extremely.

According to the seventh aspect of the invention, each time the shortage judging means judges that the heat storage preserving means is insufficient at the end of each use time zone, the heat storage means is used from the start time of the next use time zone. Since the operation in the heat storage preserving direction is configured to be incorporated by a predetermined unit time toward the scheduled end time of the time zone, the amount of heat storage becomes excessive due to an unexpected decrease in load in the latter half of the usage time zone. It is possible to avoid being wasted.

According to the eighth aspect of the present invention, the heat source generates cold heat and applies the generated cold heat to the heat medium in the heat medium circuit. While receiving and storing the cold heat from the heat medium, the stored cold heat is to be given to the heat medium, and the use-side heat exchanger is
Since the cooling medium is taken out from the heating medium in the heating medium circuit and used for cooling, an ice heat storage device having the effects of the inventions of claims 1 to 7 can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an overall configuration of a heat storage device of the present invention.

FIG. 2 is a circuit diagram showing an overall configuration of the heat storage device according to the embodiment of the present invention.

FIG. 3 is a flowchart showing main operation control of the heat storage device.

FIG. 4 is a characteristic diagram showing an operation base pattern when a peak cut operation is not performed.

FIG. 5 is a characteristic diagram of an operation pattern schematically showing the first half of a process in which the operation in the heat storage use-out direction is incorporated every time the heat storage amount is determined to be excessive.

FIG. 6 is a characteristic diagram of an operation pattern schematically showing a latter half of a process in which the operation in the heat storage use-out direction is incorporated.

FIG. 7 is a characteristic diagram of an operation pattern schematically showing a process in which an operation in a heat storage preserving direction is incorporated every time a shortage of heat storage is determined.

FIG. 8 is a characteristic diagram showing an operation base pattern when a peak cut operation is performed.

FIG. 9 is a characteristic diagram of an operation pattern schematically showing the first half of a process in which the operation in the heat storage use-out direction is incorporated every time the heat storage amount is determined to be excessive.

FIG. 10 is a characteristic diagram of an operation pattern schematically showing a latter half of a process in which the operation in the heat storage use-out direction is incorporated.

FIG. 11 is a characteristic diagram of an operation pattern schematically showing a process in which the operation in the heat storage preserving direction is incorporated every time the heat storage amount is determined to be insufficient.

[Explanation of symbols]

 (1) brine circuit (heat medium circuit) (2) chiller (heat source) (3) heat storage section (4) use side heat exchanger (13) water level sensor (heat storage amount detection means) (31) excess determination means (32) Heat storage exhaustion means (33) Shortage calculation means (34) Shortage determination means (35) Heat storage preservation means

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Shoji Morii 1304 Kanaokacho, Sakai City, Osaka Prefecture Daikin Industries, Ltd. Sakai Seisakusho Kanaoka Factory F-term (reference) 3L060 AA03 CC05 CC19 DD02 DD07 EE31 EE41

Claims (8)

[Claims] A heat medium circuit for circulating a heat medium (1)
A heat source (2) for generating heat and applying the generated heat to the heat medium in the heat medium circuit (1); and receiving and storing heat from the heat medium in the heat medium circuit (1). A heat storage unit (3) for applying the stored heat to the heat medium; and a use-side heat exchanger (4) for extracting heat from the heat medium in the heat medium circuit (1) for use. When the heat of the heat medium in the heat medium circuit (1) is not used during a non-use time period, the heat source (2) applies heat to the heat medium in the heat medium circuit (1) and the heat medium Is operated based on an operation pattern based on a heat storage operation in which the heat of the heat medium is stored in the heat storage section (3), and during a use time period in which the heat of the heat medium in the heat medium circuit (1) is used. Heat is applied to the heat medium in the heat medium circuit (1) by the heat source (2) and the heat storage section (3) A heat storage device configured to be operated based on an operation pattern based on a standard operation for applying the heat stored in the heat medium to the heat medium in the heat medium circuit (1). Heat storage amount detection means (13) for detecting the heat storage amount; and the heat storage amount detection means (13) at the end of the use time period
Excess determination means (31) for determining whether or not the remaining amount of heat, which is the amount of heat storage detected by the above, is excessive. When the excess determination means (31) determines that the remaining amount of heat storage is excessive, And a heat storage use means (32) for incorporating an operation in a heat storage use direction in which the heat stored in the heat storage unit (3) is used up in an operation pattern of a next use time zone. 2. The heat storage device according to claim 1, wherein the excess storage means determines that the excess amount of heat is excessive when the remaining amount of heat storage is within a predetermined range having a lower limit and an upper limit. A heat storage device comprising: 3. The heat storage device according to claim 1, wherein the heat storage use-up means (32) is provided each time it is determined by the excess determination means (31) that there is an excess at the end of each use time zone. A heat storage device characterized in that the operation in the heat storage use-out direction is incorporated for a predetermined unit time from the end time of the next use time zone to the start time of the use time zone. 4. The heat storage device according to claim 1, wherein when the heat storage amount detected by the heat storage amount detecting means at the end of the use time period is 0, the heat storage unit includes the heat storage unit. And (3) calculating whether or not the heat storage amount of the heat storage unit (3) is insufficient based on the shortage calculated by the shortage calculation means (33). A shortage determination unit (34) for determining whether the heat storage unit (3) has stored the heat stored in the operation pattern in the next use time zone when the shortage determination unit (34) determines that there is a shortage. A heat storage device characterized by comprising a heat storage preserving means (35) for incorporating operation in a heat storage preserving direction. 5. The heat storage device according to claim 4, wherein the shortage amount calculating means (33) terminates the use time period from the time when the heat storage amount detected by the heat storage amount detecting means (13) becomes zero. A heat storage device characterized in that it is configured to calculate a shortage amount based on the amount of heat required until then. 6. The heat storage device according to claim 4, wherein the shortage determination unit determines that the shortage is insufficient when the shortage is within a predetermined range having a lower limit and an upper limit. The heat storage device characterized by being comprised as follows. 7. The heat storage device according to claim 4, wherein the heat storage preserving means (35) each time the shortage determining means (34) determines that the heat storage is insufficient at the end of each use time zone, A heat storage device characterized in that operation in a heat storage preserving direction is incorporated for a predetermined unit time from a start time of a next use time zone to a scheduled end time of the use time zone. 8. The heat storage device according to claim 1, wherein the heat source (2) generates cold heat and transfers the generated cold heat in the heat medium circuit (1). The heat storage unit (3) receives and stores cold heat from the heat medium in the heat medium circuit (1), and applies the stored cold heat to the heat medium. A heat storage device characterized in that the use-side heat exchanger (4) is used for extracting cold heat from the heat medium in the heat medium circuit (1) to cool the heat medium.