JP2005172361A - Storage type water heater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a storage type water heater capable of determining tank heat storage quantity used in controlling a temperature of the hot water, without mounting a wasteful hot water temperature sensor in a hot water storage tank. <P>SOLUTION: A tank heat storage quantity operating means 3b is mounted on a control device 1 for controlling the overall storage type water heater, heat radiating characteristic database composed of a relational expression and a corresponding table for uniquely determining tank heat radiating quantity per a unit time corresponding to the outside air temperature, is stored in a database storing means 3c, the tank heat storage quantity operating means 3b performs the operation of natural heat radiation in accompany with the lapse of time, the operation of used heat quantity used by the hot water storage tank 1 in supplying the hot water, the operation of added heat quantity added to the hot water storage tank 1 by the operation of a heat pump unit 2, and the operation of tank heat storage quantity of the hot water storage tank 1 based on "added heat quantity-used heat quantity-natural heat radiation", and a heat pump control means 3a controls the operation of the heat pump unit 2 on the basis of results of the operations to supply the hot water of a set temperature. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention provides a hot water storage tank for storing hot water for hot water supply therein, a circulation circuit for sending the lowermost water in the hot water storage tank to the uppermost part in the hot water storage tank, and the circulation circuit. A heat pump unit that heats the flowing water to produce hot water, and controls the operation of the heat pump unit to store hot water in the hot water storage tank, and adjusts the amount of hot water supplied from the hot water storage tank to discharge hot water at the set temperature. And a hot water storage type hot water supply apparatus including the control device.

  Conventionally, there is a hot water storage type hot water supply device that stores hot water heated by a heat pump unit in a hot water storage tank. As this type of hot water supply device, the lowermost water in the hot water storage tank is heated by the heat pump unit and sent to the uppermost part of the hot water storage tank as hot water, making use of the specific gravity difference of water at different temperatures, It is known that hot water is stored in the upper side of the hot water storage tank so as not to mix with the water in the lower side of the hot water storage tank.

  When hot water in the hot water storage tank is to be supplied (for example, opening a faucet or the like to consume hot water outside the hot water storage tank), hot water is supplied from the hot water supply pipe connected to the uppermost part of the hot water storage tank, and Water is supplied into the hot water storage tank from the connected water supply pipe.

  As such a hot water storage type hot water supply device, a plurality of thermistors are installed as hot water temperature sensors in the hot water storage tank, and the hot water temperature from the top to the bottom of the tank is measured at multiple points at equal intervals, and the amount of heat stored in the tank There is a hot water storage type hot water supply apparatus that calculates the above and uses it for operation control of the heat pump unit (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 5-118660

  However, in the hot water storage type hot water supply apparatus described in Patent Document 1, a plurality of hot water temperature sensors are provided in order to detect the hot water temperature distribution in the hot water storage tank in order to calculate the amount of heat consumed by the hot water supply for a certain period. When the hot water storage tank is used only in a limited area such as hot water supply, it is sufficient to know the temperature near the outlet at the top of the tank and the inlet at the bottom of the tank. It is useless to provide a hot water temperature sensor to determine the amount of heat consumed.

  The present invention has been made in view of the above, and an object of the present invention is to provide a hot water storage type hot water supply apparatus that can determine the amount of heat stored in a tank used for hot water temperature control without providing a useless hot water temperature sensor in the hot water storage tank.

  In order to solve the above-mentioned problems, the invention according to claim 1 is a circulation system in which a hot water storage tank for storing hot water for hot water supply therein and a lowermost water in the hot water storage tank are sent to the uppermost part in the hot water storage tank. A circuit, a heat pump unit that is provided in the circulation circuit and heats the water flowing through the circulation circuit to make hot water, and controls the operation of the heat pump unit to store hot water in the hot water storage tank, and from the hot water storage tank A hot water storage hot water supply apparatus comprising a control device for adjusting the amount of hot water to be supplied and discharging hot water at a set temperature, wherein the control device has a relational expression that uniquely determines a tank heat dissipation amount per unit time according to an environmental temperature. Stores a heat dissipation characteristic database consisting of a correspondence table, calculates the amount of natural heat release with the elapsed time using the above heat dissipation characteristic database, and calculates the amount of heat used from the hot water storage tank by hot water supply The heat storage unit calculates the amount of heat added by the operation of the heat pump unit and the heat storage amount calculation means for calculating the heat storage amount of the hot water storage tank by “addition heat amount−used heat amount−natural heat release amount”, and the tank heat storage amount calculation means. Heat pump control means for controlling the operation of the heat pump unit according to the amount of heat stored in the tank.

  According to a second aspect of the present invention, there is provided the hot water storage type hot water supply apparatus according to the first aspect, wherein the control device is provided with a position at regular intervals from the uppermost part to the lowermost part of the hot water storage tank according to the environmental temperature. The temperature distribution characteristic database consisting of a relational expression and correspondence table in which the hot water temperature is uniquely determined from the heat storage amount is stored, and the heat pump control means stores the tank heat storage amount obtained by the tank heat storage amount calculation means and the temperature distribution characteristic. It is characterized in that the operation of the heat pump unit is controlled in consideration of the temperature distribution in the hot water storage tank assumed from the database.

  According to the hot water storage type hot water supply apparatus according to claim 1, the “heat pump unit obtained by calculation by the tank heat storage amount calculation means without providing the hot water temperature detection means such as a plurality of thermistors in the hot water storage tank and actually measuring the temperature distribution. The amount of heat stored in the tank can be determined from the amount of heat added by the heat source, the amount of heat used by the hot water supply, and the amount of natural heat released using the heat dissipation measurement database. Since the operation of the unit is controlled, there is no need to provide useless hot water temperature detection means.

  Moreover, according to the hot water storage type hot water supply apparatus according to claim 2, by using the temperature distribution characteristic database, the internal temperature of the hot water storage tank assumed from the tank heat storage amount obtained by the tank heat storage amount calculating means and the temperature distribution characteristic database is obtained. Considering the temperature distribution, the heat pump control means controls the operation of the heat pump unit, so that more suitable control can be expected.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a diagram showing a schematic configuration of an embodiment of a hot water storage type hot water supply apparatus according to the present invention.

  In the figure, reference numeral 1 denotes a metal (for example, stainless steel) hot water storage tank having excellent corrosion resistance, and a heat insulating material (not shown) is arranged on the outer periphery so that hot water for hot water can be kept warm for a long time. It has become.

  The hot water storage tank 1 has, for example, a vertically long cylindrical shape, and an introduction port 11 is provided on the bottom surface thereof. The introduction port 11 is a water supply pipe for introducing tap water into the lowermost part of the hot water storage tank 1. An introduction pipe 15 is connected.

  The introduction pipe 15 is provided with a water supply thermistor 21 as temperature detection means, and outputs temperature information in the introduction pipe 15 to the control device 3 (detailed later). Then, the downstream side of the position where the water supply thermistor 21 of the introduction pipe 15 is provided and the mixing valve 16 (detailed later) are connected by a pipe which is a bypass path.

  On the other hand, a lead-out port 13 is provided at the top of the hot water storage tank 1, and a lead-out pipe 14, which is a hot water supply path for leading out hot water in the hot water storage tank 1, is connected to the lead-out port 13.

  The mixing valve 16 can adjust the mixing ratio of hot water supplied from the outlet pipe 14 and tap water supplied from the pipe 15 by adjusting the opening area ratio. The mixing valve 16 is an electric valve that adjusts the opening degree of each path by driving a valve body by a drive source such as a servo motor, and is operated by a control signal from the control device 3 and controls an operating state. The data is output to the device 3.

  Connected to the outlet side of the mixing valve 16 is a pipe 17 which is a mixed hot water path to a faucet, a shower, a bath and the like. The pipe 17 is provided with a hot water supply thermistor 71 as temperature detection means and a flow rate counter 72 as hot water supply amount detection means. The hot water thermistor 71 is temperature information in the pipe 17, and the flow rate counter 72 is in the pipe 17. The flow rate information is output to the control device 3, respectively.

  A suction port 18 is provided at the lower part of the hot water storage tank 1 for sucking the water in the lowermost part of the hot water storage tank 1, and a discharge port for discharging hot water to the uppermost part of the hot water storage tank 1 at the upper part of the hot water storage tank 1. An outlet 19 is provided. The suction port 18 and the discharge port 19 are connected by a circulation circuit 20, branched by a three-way valve 23, connected to a branch pipe 20 ′ connected to the discharge port 19, and forward and return paths of the circulation circuit 20. Can be switched to reflux. A part of the circulation circuit 20 is disposed in the heat pump unit 2.

  A heat exchanger (not shown) is provided in a portion of the circulation circuit 20 arranged in the heat pump unit 2, and heat exchange of water in the hot water storage tank 1 sucked from the suction port 18 with high-temperature carbon dioxide refrigerant is performed. Then, the water in the hot water storage tank 1 can be boiled up by returning the water from the discharge port 19 into the hot water storage tank 1. As described above, when carbon dioxide, which is a natural refrigerant, is used for the heat exchanger of the heat pump unit 2, the refrigerant discharge temperature from the compressor can be increased by using the supercritical region, such as It is possible to efficiently boil hot water (for example, about 90 °) higher than in the case of adopting.

  The heat pump unit 2 is operated by a control signal from the control device 3 and outputs its operating state to the control device 3.

  Further, on the outer wall surface of the hot water storage tank 1, a tank upper thermistor 31 is disposed near the introduction port 13 on the upper surface of the tank, and a tank lower thermistor 32 is disposed near the introduction port 11 on the bottom surface of the tank. The temperature information of water is output to the control device 3.

  Further, the control device 3 is based on temperature information from the thermistors 21, 31, 32, 71, flow rate information from the flow rate counter 72, signals from operation switches provided on the operation panel 4, and the like. ON / OFF and the opening control of the mixing valve 16 are performed.

  The operation panel 4 is installed indoors such as in a bathroom or kitchen, and the hot water storage tank 1 and the heat pump unit 2 are installed in appropriate places such as outdoors. The control device 3 may be provided in the vicinity of the operation panel 4 or may be provided in the vicinity of the hot water storage tank 1 or the heat pump unit 2.

  Next, the detailed structure of the control apparatus 3 and the operation | movement of the hot water storage type hot-water supply apparatus by the control are demonstrated.

When a power switch (not shown) of the hot water storage hot water supply device is turned on, the control device 3 is based on temperature information from the thermistors 31 and 32 provided in the hot water storage tank 1, time information set by the operation panel 4, and the like. Then, the heat pump unit 2 is operated to heat the water in the hot water storage tank 1 to make hot water (for example, 90 ° hot water). The heat pump control means 3a performs this heating control.
Further, the heat pump unit 2 includes a flow rate counter that measures the amount of water passing through the heat exchanger, and measurement information of the flow rate counter is transmitted to the control device 3. Then, if the heating amount per unit water heated by the heat exchanger in the heat pump unit 2 is known, the amount of heat added by the heat pump unit 2 can be obtained from “unit heating amount × heat exchanger flow rate”. This calculation process is performed by the tank heat storage amount calculation means 3b.

  Further, the heat pump unit 2 is provided with an outside air temperature thermistor 22 that detects the temperature of the outside air. In order to prevent the circulation circuit 20 from freezing due to a temperature drop, the temperature information of the outside air temperature thermistor 22 is below a specified value. In this case, the control device 3 switches the bypass three-way valve 23 from the transfer 20 ′ side to the suction port 18 side and performs the freeze prevention operation for operating the heat pump unit 2.

  In addition, as heat dissipation characteristic information unique to the produced hot water storage type hot water supply apparatus, a relational expression in which the tank heat dissipation amount per unit time is uniquely determined at the detected temperature of the outside temperature thermistor 22 and a database of correspondence tables are created in advance. If the database is stored in the database storage means 3c of the control device 3, the amount of natural heat released from the hot water storage tank 1 is determined as "tank heat dissipation per unit time corresponding to outside temperature x duration of outside temperature". Can do. This calculation process is also performed by the tank heat storage amount calculation means 3b.

  The above-mentioned heat dissipation characteristic database is created by obtaining measured data of the amount of heat released from the tank over time, with the hot water storage tank 1 and heat pump unit 2 placed in a constant temperature environment at the prototype / experimental stage of a hot water storage type hot water supply device. it can.

  Depending on the installation environment of the hot water storage type hot water supply apparatus, the installation location of the hot water storage tank 1 and the heat pump unit 2 may be separated, and the detected temperature of the outside temperature thermistor 22 provided in the heat pump unit 2 is set as the temperature of the installation location of the hot water storage tank 1. Considering the processing, there may be a case where a large error occurs between the actual tank heat dissipation amount and the calculated tank heat dissipation amount. In such a case, separately from the outside temperature thermistor 22 provided in the heat pump unit 2, an outside temperature thermistor is provided directly or in the vicinity of the hot water storage tank 1, and the detection information of the outside temperature thermistor is used as the heat dissipation amount of the hot water storage tank 1. It may be used for the calculation of.

  When the flow rate counter 72 detects the flow of water in the pipe 17, hot water is about to be used in a faucet, shower, bath, or the like. At this time, based on the temperature information from the water supply thermistor 21, the tank upper thermistor 31, and the hot water supply thermistor 71, the control device 3 sets the mixing valve 16 so as to have an appropriate opening ratio according to the set temperature from the operation panel 4. Adjust the valve position.

  When hot water is used in this manner, from the flow rate measured by the flow rate counter 72 and the temperature information from the water supply thermistor 21 and the hot water supply thermistor 71, “(hot water supply temperature−water supply temperature) × use flow rate” The amount of heat used can be determined. Then, each time hot water is used, the amount of heat used is sequentially obtained, and the amount of heat consumed from the hot water storage tank 1 can be obtained by integrating the obtained amount of heat used. The heat storage amount calculation means 3b also performs the calculation processing of the amount of heat used and the integration processing of the heat consumption.

  As described above, by using the three parameters (addition heat amount by the heat pump unit 2, natural heat radiation amount from the hot water storage tank 1, and heat consumption amount from the hot water storage tank 1) obtained by the tank heat storage amount calculating means 3b of the control device 3. The amount of stored heat in the hot water storage tank 1 can be obtained as in the following equation.

    Tank heat storage amount = additional heat amount-heat consumption amount-natural heat dissipation amount

  Note that the amount of heat stored in the tank at the reference start time of the measurement can be estimated from the temperatures of the tank upper thermistor 31 and the tank lower thermistor 32 and the total capacity of the hot water storage tank 1 at that time. Therefore, if the amount of heat stored in the tank at the time of starting the measurement is set as an initial value, the amount of heat consumed by the hot water supply and the amount of heat lost due to natural heat dissipation are subtracted and the amount of heat added by the heat pump unit 2 is added as needed. The amount of heat stored in the tank at that time can be obtained.

  That is, in the hot water storage type hot water supply apparatus according to the present embodiment, the amount of heat stored in the hot water storage tank 1 is obtained only at the first time as a reference for starting measurement using the detected temperatures of the tank upper thermistor 31 and the tank lower thermistor 32. After that, the tank heat storage amount can be obtained at any time by the tank heat storage amount calculation means 3b of the control device 3, and the hot water supply control at the temperature set on the operation panel 4 can be performed smoothly.

  For example, when the hot water supply set temperature at the time of hot water supply is equal to or lower than the hot water supply temperature assumed from the tank heat quantity at that time, the control device 3 first brings the mixing valve 16 into communication with the water supply pipe 15 and the hot water supply pipe 17. The direction of the pipe 14 is cut off, and then the ratio of the opening area of the mixing valve 16 is roughly adjusted from the detected temperature of the water supply thermistor 21 and the detected temperature of the tank upper thermistor 31, and then based on the temperature information from the hot water supply thermistor 71. The opening area ratio of the mixing valve 16 is finely adjusted so that the hot water supply temperature becomes the set temperature, so that the hot water can be discharged at the set temperature.

  On the other hand, when the hot water supply set temperature at the time of hot water supply is higher than the hot water supply temperature assumed from the amount of heat of the tank at that time, the control device 3 operates the heat pump unit 2 to supply hot hot water from the discharge port 19 above the hot water storage tank 1. To supply hot hot water from the outlet 13 to the outlet pipe 14. In this way, if the hot water supplied from the hot water storage tank 1 to the mixing valve 16 is hot water equal to or higher than the preset temperature, the same control as in the case where the hot water hot water preset temperature at the time of hot water supply is equal to or lower than the hot water temperature assumed from the amount of tank heat. When the control device 3 performs the operation, the hot water can be discharged at the set temperature.

  In addition, the method of assuming the hot water supply temperature from the amount of heat stored in the tank used for control by the control device of the hot water storage type hot water supply apparatus according to the present embodiment is not particularly limited. For example, it can be roughly estimated from the water storage volume of the hot water storage tank 1. You may use the average hot water temperature in a tank.

  However, since there is actually a difference in hot water temperature between the upper part and the lower part of the hot water storage tank 1, the temperature of the hot water actually stored in the upper part of the hot water storage tank 1 does not operate the heat pump unit 2. If the average hot water temperature in the hot water storage tank 1 does not reach the hot water supply temperature even when the temperature is high enough, the control device 3 determines that hot water cannot be supplied at the set temperature and operates the heat pump unit 2. Become. And since the amount of natural heat radiation increases as the hot water temperature in the hot water storage tank 1 is higher, if the heat pump unit 2 is operated excessively, there is a possibility that economic efficiency will deteriorate.

  However, even if the control device 3 controls the operation of the heat pump unit 2 from the detection information of the tank upper sensor 31 that can detect the actual hot water temperature in the upper part of the hot water storage tank 1, a problem arises. For example, even if the hot water supply temperature assumed from the amount of heat stored in the tank is equal to or lower than the set temperature, the temperature detected by the tank upper sensor 31 is equal to or higher than the set temperature for hot water supply. Therefore, the controller 3 performs hot water supply control without operating the heat pump unit 2. In this case, the set temperature cannot be maintained during hot water supply, and the hot water temperature may temporarily decrease, which may impair the reliability of the hot water supply device.

  Therefore, the temperature distribution of the entire hot water in the hot water storage tank 1 in the manufactured hot water storage hot water apparatus is radiated as time elapses, and the temperature distribution characteristic information is used as the temperature distribution characteristic information. A database of relational expressions and correspondence tables in which the hot water temperature at each position from the upper part to the lowest part is uniquely determined from the amount of stored heat is created in advance, and this temperature distribution characteristic database is stored in the database storage means 3c of the control device 3. Then, since it becomes possible to predict the temperature distribution when the hot water temperature decreases due to natural heat radiation with the passage of time from the amount of heat stored in the hot water storage tank 1, it is impossible to maintain the set temperature during hot water supply. It can be determined in advance that the heat pump unit 2 is operated.

  The temperature distribution characteristic database described above was stored in the hot water storage tank 1 at a constant temperature environment by providing temperature thermistors at regular intervals from the uppermost part of the hot water storage tank 1 to the lowermost part in the prototype / experimental stage of the hot water storage type hot water supply apparatus. It can be created by changing the heat storage amount of hot water in various ways and acquiring the measured data of the temperature distribution transition over time for each heat storage amount.

  As described above, the operation of heat storage by the control device 3 that performs overall control at the time of tapping is not particularly limited. For example, in the midnight time zone where the electricity rate is low, the current heat storage amount is changed to midnight. A target heating amount to be heated by the end of the time zone (for example, a maximum heat storage amount of the hot water storage tank 1 assumed from the device performance is stored in advance, and a value obtained by subtracting the current heat storage amount from the maximum heat storage amount, that is, The amount of heat required for the reconstructed heat amount) is calculated, the heat pump unit 2 is operated so that this target heat amount can be realized, the water in the hot water storage tank 1 is boiled, and it is sufficient in the midnight time zone. You may make it ensure heat storage amount.

  In addition, an error is inevitably mixed in the heat storage amount calculated by the tank heat storage amount calculation means 3b of the control device 3, so that the difference between the actual value and the calculated value may increase as the operation time of the device increases. Therefore, the reset may be performed at an appropriate timing. For example, every day, at the end of the midnight time zone, the heat storage amount of the hot water storage tank 1 is obtained from the measured temperature of the tank upper thermistor 31 and the tank lower thermistor 32 and set as an initial value, and then after the daytime, the next midnight time zone ends. You may make it perform control using the heat storage amount by a calculation. Of course, it may be reset every week or every month.

1 is a schematic configuration diagram of a hot water storage type hot water supply apparatus according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hot water storage tank 2 Heat pump unit 3 Control apparatus 3a Heat pump control means 3b Tank heat storage amount calculating means 3c Database storage means 4 Operation panel 11 Inlet 13 Outlet 14 Outlet pipe 15 Water supply pipe 16 Mixing valve 17 Hot water supply pipe 18 Inlet 19 Discharge port DESCRIPTION OF SYMBOLS 20 Circulation circuit 20 'Branch piping 21 Water supply thermistor 22 Outside temperature thermistor 23 Bypass three way valve 31 Tank upper thermistor 32 Tank lower thermistor 71 Hot water supply thermistor 72 Flow counter

Claims (2)

A hot water storage tank for storing hot water for hot water supply,
A circulation circuit for sending the lowermost water in the hot water storage tank to the uppermost part in the hot water storage tank;
A heat pump unit that is provided in the circulation circuit and heats the water flowing through the circulation circuit to form hot water;
A controller for controlling the operation of the heat pump unit to store hot water in a hot water storage tank and adjusting the amount of hot water supplied from the hot water storage tank to discharge hot water at a set temperature;
In a hot water storage type hot water supply device comprising:
The control device
Stores a heat dissipation characteristic database consisting of relational expressions and correspondence tables that uniquely determine the tank heat dissipation per unit time according to the environmental temperature,
Calculation of natural heat dissipation with elapsed time using the above heat dissipation characteristic database, calculation of heat consumption used from hot water storage tank by hot water supply, calculation of heat addition by operation of heat pump unit, "additional heat amount-heat consumption-natural heat Tank heat storage amount calculation means for calculating the heat storage amount of the hot water storage tank by "heat dissipation amount";
Heat pump control means for controlling the operation of the heat pump unit according to the tank heat storage amount calculated by the tank heat storage amount calculation means;
A hot water storage type hot water supply apparatus comprising: In the control device,
Depending on the environmental temperature, the temperature distribution characteristic database consisting of a relational expression and correspondence table in which the hot water temperature by position at a fixed interval from the top to the bottom of the hot water tank is uniquely determined from the heat storage amount is stored,
The heat pump control means controls the operation of the heat pump unit in consideration of the temperature distribution in the hot water storage tank assumed from the tank heat storage amount obtained by the tank heat storage amount calculation means and the temperature distribution characteristic database. The hot water storage type hot-water supply device according to claim 1.

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