JP6604167B2 - Hot water storage water heater - Google Patents

Description

  The present invention relates to a hot water storage type hot water supply apparatus such as a heat pump hot water supply apparatus.

The heat pump hot water supply device is a boiling system in which hot water in a hot water storage tank is sent to a heat exchanger (condensation heat exchanger) for heating hot water in a heat pump through a predetermined hot water circulation path and heated and then returned to the hot water tank. Raising operation is possible. In general, in such a boiling operation, generally, the output of the heat pump is made constant, and the number of revolutions of the circulation pump provided in the hot water circulation path is controlled to thereby control the hot water. Is controlled to be heated to a desired temperature.
In recent years, such a type of heat pump hot water supply apparatus tends to be downsized and its output reduced from the viewpoint of reducing the size and cost of the entire apparatus.

However, when the output of the heat pump is reduced, there are the following problems.
That is, when increasing the temperature rise during hot water heating by the heat pump to, for example, about 50 to 65 ° C., it is necessary to reduce the number of revolutions of the circulation pump and considerably reduce the flow rate of hot water sent to the heat exchanger of the heat pump. There is. However, if this is done, pitting corrosion is likely to occur in the heat exchanger of the heat pump due to the fact that the flow rate of the high-temperature hot water flowing through the hot water circulation path becomes considerably low. Therefore, it is desirable to appropriately prevent this.

  In Patent Document 1, when performing a boiling operation of hot water in a hot water storage tank, the total amount of hot water in the hot water storage tank is circulated multiple times with a heat pump, thereby increasing the hot water temperature in multiple stages. The means to let you do is described. However, according to such means, although it is not necessary to make the rotational speed of the circulation pump too low, it may not be possible to accurately prevent pitting corrosion simply by performing the boiling operation a plurality of times. is there. Patent Document 1 does not mention a specific method for preventing pitting corrosion. Further, in Patent Document 1, since the entire amount of hot water in the hot water storage tank is boiled a plurality of times, it is not possible to suitably cope with boiling only part of the hot water in the hot water storage tank to a desired temperature. There is also a disadvantage that wastes to boil more than necessary.

Japanese Patent No. 4295241

  The present invention has been conceived under the circumstances as described above, and appropriately prevents pitting corrosion from easily occurring in a heat exchanger for hot water heating of an external heat source machine such as a heat pump. It is an object to provide a hot water storage type hot water supply device that can be used.

  In order to solve the above problems, the present invention takes the following technical means.

The hot water storage type hot water supply apparatus provided by the present invention is provided in a hot water storage path, an external heat source unit having a heat exchanger for heating hot water, and a hot water circulation path connecting the heat exchanger and the hot water storage tank,
And, using this hot water circulation path, the hot water in the hot water storage tank is sent to the heat exchanger to be heated and then heated to return to the hot water storage tank. A hot water storage type hot water supply apparatus comprising a control means capable of controlling the hot water heating temperature by the heat exchanger by changing the control means when performing the boiling operation, When boiling water in the hot water storage tank is boiled up to a target boiling temperature at a time, the rotation speed of the circulation pump or a parameter corresponding thereto is not more than a predetermined value, and the target boiling temperature is a predetermined temperature. It is determined in advance whether or not the specific condition is met, and when it is determined that the specific condition is satisfied, the specific condition is not applied. A pre-boiling operation for raising the total amount of hot water in the hot water storage tank to a temperature lower than the target boiling temperature after increasing the rotation speed of the ring pump, and then hot water in the hot water storage tank; It is characterized in that it is configured to perform a control to perform an operation of boiling up to the target boiling temperature.
Here, the “parameter” corresponds to, for example, the flow rate or flow velocity of hot water in the hot water circulation path.

According to the configuration of the present invention described above, the following effects can be obtained.
That is, when boiling hot water in a hot water storage tank is heated to a target boiling temperature, the number of rotations of the circulation pump or a parameter corresponding thereto is not more than a predetermined value, and the target boiling temperature is not less than a predetermined temperature. When the condition is met, a preliminary boiling operation is performed so as to avoid such a state, and then the boiling to the target boiling temperature is performed. Therefore, it is avoided that hot hot water flows through the hot water circulation path connecting the heat exchanger of the external heat source machine and the hot water storage tank at a considerably low speed, and appropriately prevents pitting corrosion from occurring easily in the heat exchanger. be able to. Such a pitting corrosion prevention effect is an effect that cannot be obtained by the means described in Patent Document 1 in which the boiling operation is simply performed in a plurality of times without considering the flow rate of high-temperature hot water in the hot water circulation path. It is.
Further, according to the present invention, at the time of the final boiling performed after the preliminary boiling operation, it is only necessary to boil the necessary amount of hot water, and it is not always necessary to boil the total amount of hot water in the hot water storage tank. Therefore, the efficiency is high, and it is possible to prevent a lot of waste from occurring in the heated hot water.

  In the present invention, it is preferable that the predetermined value in the specific condition is a value for the number of rotations of the circulation pump, and the circulating pump has a flow rate of hot water in the hot water circulation path of 0.2 m / sec. The predetermined temperature under the specific condition is 60 ° C. or lower.

According to such a configuration, the following effects can be obtained.
For example, a heat exchanger for heating hot water of an external heat source machine such as a heat pump generally tends to cause pitting corrosion when the flow rate of hot water flowing inside is 0.2 m / sec or less and 60 ° C. or more. It has been found. On the other hand, according to the said structure, it is avoided appropriately that it corresponds to the said conditions which are easy to produce pitting corrosion, and a pitting corrosion prevention effect can be improved more.

  In the present invention, it is preferable that, when only a part of hot water in the hot water storage tank is heated to the target boiling temperature, the control means uses a temporary target boiling temperature during the preliminary boiling operation. The hot water supply set temperature is set to be higher.

According to such a configuration, even after a hot water boiling operation in the hot water storage tank, even if a part of the hot water heated to the target boiling temperature is consumed for hot water supply, In this case, hot water having a temperature higher than the hot water supply set temperature remains. Therefore, even if the need for hot water further arises thereafter, the remaining hot water in the hot water storage tank can be used for hot water supply. Since there is no need to further heat the residual hot water, energy efficiency can be improved.

  Other features and advantages of the present invention will become more apparent from the following description of embodiments of the present invention with reference to the accompanying drawings.

It is a schematic explanatory drawing which shows an example of the hot water storage type hot water supply apparatus which concerns on this invention. It is a flowchart which shows the example of the operation control performed in the heat pump of FIG.

  Hereinafter, preferred embodiments of the present invention will be specifically described with reference to the drawings.

  A hot water storage type hot water supply device WH shown in FIG. 1 is a heat pump hot water supply device, and includes a heat pump H and a hot water storage tank unit U.

The heat pump H includes a refrigeration cycle 1 similar to that conventionally known. The refrigeration cycle 1 includes, for example, an evaporative heat exchanger 10 for absorbing heat from the outside air (atmosphere), a compressor 11, and a heat exchanger 12 for heating hot water (condensation heat) on a circulation flow path of a refrigerant such as CO _2. An exchanger) and an expansion valve 13 are provided.

  The hot water storage tank unit U is provided in the forward and backward piping portions 3a and 3b and the outward piping portion 3b that constitute the hot water circulation path 3 that connects the hot water storage tank 2, the heat exchanger 12 of the heat pump H, and the hot water storage tank 2. A circulation pump P, a main control unit 4 to which a remote controller 40 is connected, and an auxiliary heat source unit 8.

  Hot water replenishment from the outside to the hot water storage tank 2 is performed via a lower pipe 50 connected to the lower part of the hot water storage tank 2. The lower end of the lower pipe 50 is a water inlet 50 a to which a water supply pipe 90 is connected. For example, tap water sent from the water supply pipe 90 flows into the hot water storage tank 2. The circulation pump P has a variable rotational speed (the number of rotations), and by driving the circulation pump P, hot water existing in the lower region in the hot water storage tank 2 passes through the piping portion 3b on the outgoing side of the hot water circulation path 3. Then, a heating operation can be performed in which the water is sent to the heat exchanger 12 of the heat pump H and heated, and thereafter passes through the return side piping section 3a and is returned to the upper portion in the hot water storage tank 2. In the boiling operation, the boiling temperature of the hot water can be controlled by changing the rotation speed of the circulation pump P. The hot water heated using the heat pump H is stored sequentially from the upper side to the lower side in the hot water storage tank 2. The hot water storage tank 2 is provided with a plurality of temperature sensors Sa for detecting the internal hot water temperature at appropriate intervals in the vertical direction, and the temperature distribution of the hot water in the hot water storage tank 2 and It is possible to judge the amount of heat storage based on this. A temperature sensor Sb for detecting an incoming water temperature Ta to the heat pump H (an incoming water temperature to the heat exchanger 12) is provided in the outgoing piping section 3b.

Hot water is discharged from the hot water storage tank 2 through an upper pipe 51 connected to the upper part of the hot water storage tank 2. For example, a hot water tap 91 and a bathtub 92 are connected to the hot water outlet 51 a at the end of the upper pipe 51 and the hot water outlet 52 a of the pipe 52 branched and connected to the upper pipe 51. Has been. Although illustration explanation is omitted, it is also possible to branch-connect a pipe that enables hot water supply to the hot water heating terminal to the upper pipe 51. The auxiliary heat source unit 8 is configured such that the hot water temperature discharged through the upper pipe 51 is the hot water supply set temperature Tc (the hot water supply temperature set by the user using the remote controller 40 or the hot water supply temperature set by the main control unit 4 according to various conditions. ) For heating the hot water when it is less. The auxiliary heat source unit 8 is a combustion type heat source unit that includes a burner 80 that burns fuel gas and a heat exchanger 81 that performs hot water heating using the combustion gas generated by the burner 80. The upper pipe 51 is also provided with an overflow prevention valve V1, a mixing valve V2 for controlling the amount of hot water mixed into the upper pipe 51 from the branch pipe 53 branched and connected to the lower pipe 50, and the like.

  The main control unit 4 performs operation control of each part of the hot water storage hot water supply device WH and various data processing controls by cooperating with the auxiliary control unit 4A provided in the heat pump H, and is referred to in the present invention. It corresponds to an example of a control means. The main control unit 4 is configured to execute control as described later when boiling water in the hot water storage tank 2 is boiled to a target boiling temperature Tt in accordance with heat demand.

  Next, an example of the operation of the hot water storage type hot water supply device WH and an operation processing procedure executed by the main control unit 4 will be described with reference to the flowchart shown in FIG.

  In the case where the hot water boiling operation in the hot water storage tank 2 is performed, a pre-hot water circulation operation is executed prior to this (S1). This pre-hot water circulation operation is for confirming whether or not the boiling operation can be normally executed by driving the circulation pump P for a predetermined time, but by executing this operation, Data such as the temperature Ta of water entering the heat pump H is collected. In accordance with the pre-hot water circulation operation described above, the main control unit 4 includes conditions such as the target boiling temperature Tt (final boiling target temperature), the output of the heat pump H, and the outside air temperature in addition to the incoming water temperature Ta to the heat pump H. Based on the above, the number of revolutions Na of the circulation pump P required to boil hot water in the hot water storage tank 2 to the target boiling temperature Tt at once is obtained (S2).

Next, the main control unit 4 determines whether or not both of the following a and b (a and b) are satisfied as the specific condition (S3).
Specific conditions:
a. Rotation speed Na of circulation pump P ≦ predetermined rotation speed N1
b. Target boiling temperature Tt ≧ predetermined temperature Tb
Here, the predetermined rotational speed N1 is, for example, the rotational speed of the circulating pump P at which the flow rate of hot water in the hot water circulation path 3 is 0.2 m / sec, or a higher rotational speed (for example, the flow speed is 0.2 m / sec). The number of rotations obtained by adding an appropriate margin to the number of rotations. Since the flow rate of hot water varies depending on the capacity of the circulation pump P, the inner diameter of the hot water circulation path 3, and the like, the rotational speed N1 of the circulation pump P is determined in consideration of these factors.
The predetermined temperature Tb is, for example, 60 ° C. or a temperature lower than this (in consideration of various errors, the temperature is appropriately lower than 60 ° C., for example, any one of 57 to 59 ° C.).

  When the main controller 4 determines that the specific condition is not met, the main controller 4 performs a normal boiling operation, that is, an operation of boiling hot water in the hot water storage tank 2 to the target boiling temperature Tt at once by the heat pump H. (S3: NO, S8). When the amount of boiling reaches the amount of heat demand that is predicted, the boiling operation is completed (S9: YES, end). If the specific condition is not met, the flow rate of hot water flowing through the hot water circulation path 3 is 0.2 m / sec or less and the hot water temperature does not reach 60 ° C. or higher. Even so, there is no possibility that the heat exchanger 12 is likely to cause pitting corrosion.

  On the other hand, when it is determined that the specific condition is satisfied (S3: YES), in other words, when it is determined that pitting corrosion is likely to occur in the heat exchanger 12, hot water to be heated to the target boiling temperature Tt. However, depending on whether the total amount of water in the hot water storage tank 2 is “boiling up” or “partial boiling”, different control is performed as described below.

In the case of “boiling all”, the following control is performed.
After the rotational speed of the circulation pump P is set to a rotational speed Nb higher than the predetermined rotational speed N1 in the specific condition, boiling (preliminary boiling) of hot water in the hot water storage tank 2 is started (S4: NO, S7). The rotational speed Nb is, for example, the rotational speed of the circulation pump P at which the flow rate of hot water in the hot water circulation path 3 is about 0.4 m / sec. However, other rotation speeds can be used. Furthermore, the rotation speed Nb is not a fixed value, and may be changed as appropriate according to various conditions.

  Thereafter, when the preliminary boiling of the entire amount of hot water in the hot water storage tank 2 is completed and the incoming water temperature Ta to the heat pump H rises, the main control unit 4 performs the processing of step 2 described above, that is, the circulation pump P. The process for obtaining the rotational speed Na is executed again (S6: YES, S2). This is because, in the preliminary boiling described above, the circulating pump P is driven at a higher speed than the original number of revolutions, so that the hot water in the hot water storage tank 2 is heated to the target boiling only by preliminary boiling. It is difficult to boil up to the temperature Tt, because it is necessary to perform a re-boiling operation, and it is necessary to prevent pitting corrosion of the heat exchanger 12 even during this re-boiling. As a result of the above-described preliminary boiling, when the specific condition is not met, a normal boiling operation with the boiling temperature as the target boiling temperature Tt is performed thereafter, and the hot water in the hot water storage tank 2 is heated. The whole amount is boiled (S3: NO, S8, S9).

  Unlike the above, if it is determined in step S3 that the specific condition is still satisfied, the preliminary boiling operation is repeated and the final boiling is not performed when the specific condition is not satisfied. The raising operation is executed (S3: YES, S4: NO, S7, S6: YES, S2, S3: NO, S8, S9). However, in normal hot water storage operation, in most cases, it is considered that the number of preliminary boiling operations is only one.

  According to the series of operation control described above, when boiling hot water, it is appropriately avoided that the flow rate of the hot water flowing through the hot water circulation path 3 is a low speed of 0.2 m / sec or less. It is possible to appropriately prevent or suppress the pitting corrosion occurrence phenomenon of the heat exchanger 12 due to the decrease in the flow velocity of the heat exchanger 12.

In the case of “partial boiling”, the following control is performed.
First, the point that the preliminary boiling is performed in a state where the rotational speed of the circulation pump P is higher than the predetermined rotational speed N1 in the specific condition is the same as in the case of “boiling of the whole amount”. However, when performing the preliminary boiling, the main control unit 4 sets a temperature higher than the hot water supply set temperature as the temporary target boiling temperature Tt ′, and the rotational speed of the circulation pump P is set to the temporary target boiling. It is set as the rotation speed which can be heated up at temperature Tt '(S4: YES, S5). The basic control other than this is the same as in the case of “boiling of the whole amount”, and the final boiling operation is executed at the stage where the specific conditions are not met as a result of the preliminary boiling. (S6: YES, S2, S3: NO, S8, S9: YES, end). However, in this case, only part of the hot water in the hot water storage tank 2 is heated to the target boiling temperature Tt.

  In such a series of operation control, as in the case of “boiling of the whole amount” described above, the pitting corrosion occurrence phenomenon of the heat exchanger 12 due to the decrease in the flow rate of the hot water is appropriately prevented or suppressed. Is possible. In addition, after the above-described boiling was completed, some of the hot water in the hot water storage tank 2 was heated to the target boiling temperature Tt, and other hot water was heated to a temperature higher than the hot water supply set temperature. Is in a state. For this reason, even if there is further heat demand after the consumption of the part of hot water, the hot water supply operation at the hot water supply set temperature can be appropriately performed in response to this. In this case, for example, it is not necessary to perform hot water heating using the auxiliary heat source unit 8, so that energy efficiency is good.

The present invention is not limited to the contents of the above-described embodiment. The specific configuration of each part of the hot water storage type hot water supply apparatus according to the present invention can be variously modified within the range intended by the present invention.

  In the above-described embodiment, as a method for determining whether or not the flow rate of the hot water in the hot water circulation path is equal to or lower than the predetermined flow rate, it is determined whether the rotation speed of the circulation pump is equal to or lower than the predetermined rotation speed N1. . However, this invention is not limited to this, You may use parameters other than the rotation speed of a circulation pump. As already described, for example, the flow rate or flow rate of hot water in the hot water circulation path can be used as this parameter.

  In the above-described embodiment, when preliminary boiling is performed on the premise of “partial boiling” in step S5 of FIG. 2, the temporary target boiling temperature Tt ′ that is higher than the hot water supply set temperature is set. However, the present invention is not limited to this, and the rotational speed of the circulation pump P is simply set to the predetermined rotational speed without setting the temporary target boiling temperature Tt ′ as in the case of “boiling of the whole amount” in step S7. Preliminary boiling may be performed higher than N1. On the other hand, in the case of “total boiling” in step S7, a temporary target boiling temperature Tt ′ that is higher than the hot water supply set temperature may be set.

  The external heat source machine is not limited to a heat pump. For example, the present invention is also applied to a case where hot water in a hot water storage tank is fed into a heat exchanger for hot water heating in a cogeneration system and the boiling temperature is controlled by controlling the rotation speed of a circulation pump. Can do.

WH Hot water storage type water heater H Heat pump (external heat source machine)
U Hot water storage tank unit P Circulation pump 12 Heat exchanger (Condensation heat exchanger: Heat exchanger for hot water heating)
2 Hot water storage tank 3 Hot water circulation path 4 Main control unit (control means)

Claims (3)

A hot water storage tank,
An external heat source machine having a heat exchanger for hot water heating,
It is provided in a hot water circulation path connecting the heat exchanger and the hot water storage tank, and hot water in the hot water storage tank is sent to the heat exchanger by using this hot water circulation path, and then heated in the hot water storage tank. A circulating pump that enables return boiling operation;
Control means capable of controlling the hot water heating temperature by the heat exchanger by changing the rotational speed of the circulation pump;
A hot water storage hot water supply device comprising:
The control means includes
In the case of performing the boiling operation, when the hot water in the hot water storage tank is boiled up to a target boiling temperature at a time, the rotation speed of the circulation pump or a parameter corresponding thereto is a predetermined value or less, In addition, it is determined in advance whether or not the specific condition that the target boiling temperature is equal to or higher than a predetermined temperature is satisfied, and if it is determined that the specific condition is satisfied, the circulation is performed so that the specific condition is not satisfied. After increasing the number of revolutions of the pump, a preliminary boiling operation is performed in which the entire amount of hot water in the hot water storage tank is heated to a temperature lower than the target boiling temperature, and then hot water in the hot water storage tank is discharged. A hot water storage type hot water supply apparatus configured to perform a control to perform a boiling operation to the target boiling temperature. The hot water storage type hot water supply device according to claim 1,
The predetermined value in the specific condition is a value for the rotation speed of the circulation pump, and the rotation speed of the circulation pump at which the flow rate of hot water in the hot water circulation path is 0.2 m / sec, or more. And the number of rotations
The hot water storage type hot water supply apparatus in which the predetermined temperature in the specific condition is 60 ° C. or lower. The hot water storage type hot water supply device according to claim 1 or 2,
The control means includes
When only a part of hot water in the hot water storage tank is heated to the target boiling temperature, a temperature higher than the hot water supply set temperature is set as a temporary target boiling temperature during the preliminary boiling operation. This is a hot water storage type hot water supply device.

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