JP2010054131A - Storage type hot water supply device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a storage type hot water supply device surely estimating temperature distribution of hot water and water in a hot water storage tank by directly solving a heat energy balancing formula. <P>SOLUTION: This storage type hot water supply device includes: the hot water storage tank; a heating means for heating the hot water/water in the hot water storage tank; a load side circuit for supplying the hot water/water in the hot water storage tank to a load side; a temperature sensor for measuring a temperature of the hot water/water flowing into the hot water storage tank, a flow rate sensor for measuring a flow rate of the hot water/water flowing into the hot water storage tank; and a temperature sensor for detecting an outside air temperature, and it further includes a temperature distribution calculating means for calculating a temperature of each layer inside of the hot water storage tank vertically divided into the plurality of layers on the basis of a temperature measurement value of the temperature sensor and a flow rate measurement value of the flow rate sensor, on the basis of the summation of inflow heat quantity from a pipe connected to each layer, heat radiation based on difference between a temperature of each layer and the outside air temperature, and a heat transferring amount of each layer to the layers vertically adjacent thereto. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a hot water storage type hot water supply apparatus, and more particularly to a hot water storage type hot water supply apparatus provided with a temperature distribution calculating means of a hot water storage tank.

  Conventionally, in a hot water storage hot water supply device such as a heat pump hot water supply device, by circulating water in the tank between the hot water storage tank and the heat pump heating means, hot water is returned to the upper part of the tank and boiled up. At that time, a large number of temperature sensors were provided in the hot water storage tank to grasp the temperature distribution in the tank and to estimate the heat storage amount. However, if hot water and low-temperature water exist in the hot water storage tank, a temperature boundary layer is generated between them, so there is a problem that accurate heat storage cannot be estimated unless the position and temperature distribution state of the temperature boundary layer are known. It was.

  As a solution to this problem, when boiling hot water in a hot water storage tank, the hot water in the tank moves and passes through the position of a temperature sensor provided in the hot water storage tank over time. A method of estimating the temperature distribution of the mixed layer (temperature boundary layer) based on the temperature history of the sensor and the moving speed of hot water in the hot water storage tank is known (for example, see Patent Document 1).

JP 2006-214622 A (page 3-4, FIG. 1)

  However, in the invention disclosed in Patent Document 1, since the temperature distribution of the hot water in the hot water storage tank is not known unless the hot water passes through the position of the temperature sensor, the hot water storage amount depends on the position of the temperature sensor and the hot water movement speed. Depending on the situation, the temperature distribution cannot be calculated, and there is a problem that the time during which the heat storage amount cannot be grasped continues for a long time. In order to solve the above problem, it is possible to solve the problem by installing a large number of temperature sensors, but the problem that the cost becomes high remains.

  In addition, in a multi-function hot water storage hot water supply device that connects a hot water storage tank to a bath (tub water) reheating heat exchanger, floor heating heat exchanger, etc., intermediate hot water (about 30-50 ° C.) is provided in the middle of the hot water storage tank. However, the temperature distribution in the hot water storage tank fluctuates in a complicated manner. However, in the invention disclosed in Patent Document 1, an accurate temperature is maintained until the hot water in the hot water storage tank moves and passes through the temperature sensor again. There was a problem that the distribution could not be grasped.

  The present invention has been made to solve the above-described problems, and provides a hot water storage type hot water supply apparatus that can accurately estimate the temperature distribution of hot water in a hot water storage tank by directly solving the thermal energy balance equation. The purpose is to provide.

  The hot water storage type hot water supply apparatus according to the present invention includes a hot water storage tank, heating means for heating hot water in the hot water storage tank, a load side circuit for supplying hot water in the hot water storage tank to a load side, and hot water flowing into the hot water storage tank. A temperature sensor that measures temperature, a flow sensor that measures the flow rate of hot water flowing into the hot water storage tank, a temperature sensor that detects the outside air temperature, a temperature measurement value of the temperature sensor, and a flow rate measurement value of the flow sensor. Based on the temperature of each layer divided into a plurality of layers in the hot water storage tank in the vertical direction, the amount of heat input from the pipe connected to each layer, the amount of heat released based on the difference between the temperature of each layer and the outside air temperature, On the other hand, it is provided with a temperature distribution calculating means for calculating from the sum of the heat transfer amounts with the layers adjacent in the vertical direction.

  In the hot water storage type hot water supply apparatus according to the present invention, the temperature of each layer obtained by dividing the hot water storage tank into a plurality of layers in the vertical direction is calculated based on the difference between the amount of heat input from the pipe connected to each layer and the temperature of each layer and the outside air temperature. Calculated from the sum of the heat dissipation amount based on the heat dissipation amount of the layers adjacent to the upper and lower layers, that is, equipped with temperature distribution calculation means for directly solving the thermal energy balance equation. Can be accurately estimated. In addition, the temperature distribution calculating means can determine an accurate temperature distribution that takes into account temperature mixing caused by the inflow of medium-temperature water.

  Embodiments of a hot water storage type hot water supply apparatus according to the present invention will be described below with reference to the drawings.

Embodiment 1 FIG.
"overall structure"
FIG. 1 is a configuration diagram showing an overall configuration of a hot water storage type hot water supply apparatus according to Embodiment 1 of the present invention, and FIG. 2 is a schematic configuration diagram showing an outline of a control system of the hot water storage type hot water supply apparatus.
The hot water storage type hot water supply apparatus according to the present embodiment includes a hot water storage unit A, a heat source unit B, and a load side circuit C.
The hot water storage unit A includes a hot water storage tank 1, a general hot water supply side mixing valve 2a, a bath side mixing valve 2b, a pressure reducing valve 3, a solenoid valve 4, a control unit 10, water pumps 14a, 14b, 14c, a bath recuperation heat exchanger 15, A heat insulating material 20 is provided (sensors and piping will be described later), and these components are housed in a metal outer case 30. The hot water storage tank 1 is made of metal such as stainless steel or resin, and a heat insulating material 20 is disposed outside the hot water storage tank 1 so that hot water (hereinafter referred to as high temperature water) can be kept warm for a long time. it can. The primary side of the bath remedy heat exchanger 15 is connected with an outgoing pipe 25 from the upper part of the hot water storage tank 1 and a return pipe 26 to the intermediate part of the hot water storage tank 1, and a reciprocating pipe with the bathtub 5 on the secondary side. 27 is connected. Pumps 14 b and 14 c are connected to the primary side and secondary side flow paths of the bath remedy heat exchanger 15, respectively. In FIG. 1, the tank is shown as one configuration example, but two or more hot water storage tanks may be connected in series or in parallel and installed in the hot water storage unit A.

The heat source unit B has a built-in heater (not shown) such as a heat exchanger that heats up water at a city water temperature (hereinafter referred to as water or low-temperature water) to a target hot water temperature. The heat source unit B is a heat pump that uses, for example, HFC or CO ₂ as a refrigerant, a compressor (not shown), a water heat exchanger (condenser, not shown) that exchanges heat between water and the refrigerant, outside air And an air heat exchanger (evaporator, not shown), an expansion valve (not shown), etc. for exchanging heat between the refrigerant and the refrigerant. Further, instead of the heat pump, the heating source may be replaced with an electric heater, gas, or the like, or the heating source may be built in the hot water storage tank 1.

  In the load side circuit C, for example, a bathtub 5 that stores hot water supplied from the bath side mixing valve 2b, hot water supplied from the general hot water side mixing valve 2a, and city water supplied from a water source are mixed. A mixing plug 6 for supplying hot water or a floor heating device (not shown) is connected. A shower (not shown) may be connected to the mixing plug 6. Reference numeral 7 denotes a remote controller capable of information input / output (setting of hot water supply temperature, start or stop operation of hot water supply to a bathtub, etc.) with a hot water storage system composed of a hot water storage unit A and a heat source unit B. A plurality of remote controllers 7 may be installed for the bath side and kitchen.

Next, the piping configuration of the hot water storage system will be described.
The city water temperature water supplied from the water source is branched into the hot water storage tank 1, the mixing valves 2 a and 2 b, and the mixing plug 6. Connected to the lower part of the hot water storage tank 1 are a city water introduction pipe 21 and a pipe 23 for feeding the water in the lower part of the hot water storage tank 1 to the heat source unit B. The water sent from the lower part of the hot water storage tank 1 is heated to the target temperature by the heat source unit B, and returned to the upper part of the hot water storage tank 1 via the pipe 24 connected from the heat source unit B to the upper part of the hot water storage tank 1. Water circulation between the hot water storage tank 1 and the heat source unit B is performed by a pump 14a. The pump 14a may be built in the heat source unit B.

  In the upper part of the hot water storage tank 1, a hot water outlet pipe 22 is provided in addition to the primary side outgoing pipe 25 of the bath recuperation heat exchanger 15, and the hot water discharged from the hot water storage tank 1 is supplied with the pipe 22. Are branched into two from the hot water supply side mixing valve 2a and the bath side mixing valve 2b. On the other hand, a water pipe 28 from a water source is branched and connected to the water side inlets of the mixing valves 2a and 2b through the pressure reducing valve 3 so that hot water and water are mixed in the mixing valves 2a and 2b. Each hot water is supplied as hot water of temperature. On the bath side, the bath-side mixing valve 2b and the bathtub 5 are connected by a pipe 29 via the electromagnetic valve 4, and the hot water supplied from the bath-side mixing valve 2b is stored in the bathtub 5. On the general hot water supply side, the hot water supplied from the general hot water supply side mixing valve 2a via the pipe 30 is mixed with the water supplied from the water source via the water pipe 31 and supplied from the mixing tap 6. ing.

  In the example of FIG. 1, the configuration of the mixing tap 6 is taken as an example, but the mixing tap is connected to, for example, a kitchen faucet, a bathroom faucet, a bathroom currant and shower, and the like. It is good also as a structure corresponding to each mixing plug by increasing the number of mixing valves. Further, the mixing valves 2a and 2b are electric valves that drive the valve body by a drive source such as a servo motor, for example, and a structure capable of controlling the hot water supply temperature by adjusting the mixing ratio of high-temperature water and water by moving the valve body. belongs to.

Next, sensors and a control unit provided in the hot water storage unit A will be described.
A flow rate sensor for measuring the hot water supply flow rate is provided on the outlet side of the mixing valves 2a and 2b, a flow rate sensor 11a is provided on the outlet side of the general hot water supply side mixing valve 2a, and a flow rate is provided on the outlet side of the bath side mixing valve 2b. A sensor 11b is provided, and a flow rate sensor 11c for measuring the flow rate of water circulating between the heat source unit B and the hot water storage tank 1 when boiling the water in the hot water storage tank 1 is provided. A flow rate sensor 11 d is provided for measuring the water flow rate of the primary flow path that flows between the hot water storage tank 15 and the hot water storage tank 1. And the temperature sensor which measures the temperature of the hot water flowing through each piping is provided. That is, the temperature sensor 12c is used to measure the water temperature at the water inlet of the mixing valves 2a and 2b, and the temperature sensor 13a is used to measure the temperature of the hot water at the hot water inlet of the mixing valves 2a and 2b and the temperature at the top of the tank. 1, the temperature sensor 13a is provided on the surface of the can at the upper part of the tank, but it may be configured to directly measure the temperature of the hot water inside the tank upper part of the tank). The temperature sensor 12a is provided with a temperature sensor 12b for measuring the hot water supply temperature on the outlet side of the bath-side mixing valve 2b, and a temperature sensor 12d for measuring the boiling temperature of hot water heated by the heat source unit B. Further, a temperature sensor 12f is used for measuring the temperature of the return water to the hot water storage tank 1 on the primary side connected to the bath reheating heat exchanger 15, and a temperature sensor 12f is used for measuring the return water temperature from the bathtub 5 on the secondary side. Temperature sensor 12e is provided That. In addition to the temperature sensor 13a, the hot water storage tank 1 is provided with a temperature sensor 13b for measuring the hot water temperature in the intermediate portion of the hot water tank. A temperature sensor 16 for measuring the outside air temperature is provided in the exterior case 30. Each of the temperature sensors 12a to 12f, 13a, and 13b is brazed to the surface of the pipe or tank, welded, screwed, fixed to a folder, or the like, or inside the pipe or tank to directly measure the water temperature. An installation method in which the sensor is immersed may be used.

FIG. 2 shows a connection configuration of sensors connected to the control unit 10, the remote controller 7, the heat source unit B, and valves (mixing valve, electromagnetic valve). The control unit 10 and the sensors are wired by a communication cable so that signals can be exchanged. The communication between the control unit 10 and the sensors may be via wireless.
The control unit 10 is built in the hot water storage unit A, and includes a measurement unit (not shown) that measures sensors such as temperature and flow rate, and a calculation unit that performs processing such as calculation, comparison, and determination based on the measurement results (see FIG. (Not shown), a driving unit (not shown) for driving valves and the like based on the calculation result, and a transmission / reception unit (not shown) for transmitting / receiving operation information to the heat source unit B and the like. In addition, a storage unit (not shown) that stores approximate expressions and tables for calculating results obtained by the calculation unit and predetermined functions is also built in, and the stored contents are referred to as necessary. It is possible to rewrite. The processes such as measurement, calculation, and driving are processed by a microcomputer, and the storage unit is constituted by a semiconductor memory or the like. Further, the processing result by the microcomputer is displayed on the control unit 10 by an LED or a monitor, a warning sound or the like is output, or a communication means (not shown) such as a telephone line, a LAN line, or a wireless communication is used to reach a remote place. An output unit (not shown) for outputting information, an operation input from a remote controller or a switch on the board, or an input for inputting communication data information from a communication means (not shown) such as a telephone line, a LAN line, or a radio. A portion (not shown) is provided. In the above configuration example, the control unit 10 is built in the hot water storage unit A, but the main control unit is provided in the hot water storage unit A, and the sub control unit having a part of the function of the control unit is provided on the heat source unit B side. The main control unit and the sub-control unit may perform data communication to perform cooperative processing, a configuration in which the remote controller has those functions, or a configuration in which a control unit is provided outside the hot water storage unit A. Good.

<Explanation of hot water storage operation>
The high-temperature water boiled in the heat source unit B, which is a heating source, flows into the hot water storage tank 1 from above through a pipe 24 connecting the heat source unit B and the hot water storage unit A. A volume of water (high-temperature water or low-temperature water) flowing into the hot water storage tank 1 moves from the upper part to the lower part of the hot water storage tank 1. Then, low temperature water corresponding to the inflow volume is discharged from the lower part of the hot water storage tank 1 by the water pump 14a, and returns to the heat source unit B through the pipe 23 connected to the pipe. In this way, a circulation circuit is formed between the heat source unit B and the hot water storage tank 1, and the low temperature water in the hot water storage tank 1 is sequentially heated to a high temperature and stored in the hot water storage tank 1. This hot water storage operation is basically performed at night when the electricity rate is low, but if the amount of stored hot water is insufficient during the day, it can also be operated during the day (additional boiling) to prevent running out of hot water. It becomes possible.

<Explanation of hot water supply operation>
The boiling water temperature of the hot water storage tank 1 can be set in advance by the remote controller 7, and the water temperature of the hot water storage tank 1 is heated to the target boiling water temperature by the heat pump heat source of the heat source unit B at midnight. Further, the hot water supply temperature on the general hot water supply side and the set temperature of the bathtub can be set in advance by the remote controller 7. In addition, when the amount of hot water storage is insufficient during daytime hours, it is possible to compensate for the shortage of hot water storage by operating the heat source unit B and storing additional hot water in the hot water storage tank 1.

(Hot-water supply operation to the general hot water supply side)
When the mixing tap 6 is opened, the control unit 10 controls the general hot water supply side mixing valve 2a so that the temperature detected by the temperature sensor 12a on the general hot water supply side becomes the set hot water supply temperature. Hot water to be supplied with hot water and water from a water source are mixed at an appropriate temperature (for example, 42 ° C.).

(Hot-water supply operation to the bath hot-water supply side)
The hot water supply temperature to the bathtub 5 can be set in advance by the remote controller 7 and the hot water supply operation to the bathtub 5 is performed. In order to fill the hot water, first press the hot water switch with the remote controller 7. As a result, a hot water filling command is output, and the control unit 10 controls the bath hot water supply side mixing valve 2b so that the temperature detected by the bath side temperature sensor 12b is set, and the piping 29 The solenoid valve 4 provided in is opened and hot water filling to the bathtub 5 is started. After the hot water filling to the bathtub 5 is started, the integrated flow rate is counted by the flow rate sensor 11b provided in the pipe 29 on the bathtub side, and the hot water filling is continued until the amount of the hot water bath set in advance by the remote controller 7 is reached. When the integrated flow rate reaches the set amount of bathtub hot water, the solenoid valve 4 is closed to complete the hot water filling.

(Memorial operation of bathtub water)
In accordance with a command from the remote controller 7, a memorial operation when the bathtub water is cooled is executed. When the chasing operation is started, the pumps 14b and 14c connected to the primary side and secondary side channels of the bath chasing heat exchanger 15 are driven. Thereby, it becomes possible to heat-exchange the hot water of the hot water storage tank 1 and the hot water of the bathtub 5, and the heating of the bathtub water can be tracked. At this time, medium temperature water (about 40 to 60 ° C.) after heat exchange with the bath water is returned to the hot water storage tank 1 side from the intermediate portion in the vertical direction of the hot water storage tank 1 or the pipe 26 connection portion at the bottom. In the hot water storage tank 1, the hot water in the hot water storage tank 1 connected to the pipe 26 is mixed with the hot water returning from the bath reheating heat exchanger 15, and the temperature distribution in the hot water storage tank 1 is complicated due to the temperature difference between the two. To change.

(Method for estimating hot water temperature distribution in hot water storage tanks)
In order to accurately estimate the temperature distribution of the hot water in the hot water storage tank 1, it is necessary to solve the flow and temperature diffusion in the tank in consideration of the influence of the water flow and the buoyancy caused by the temperature difference. An analysis method for solving the temperature distribution in the hot water storage tank in consideration of the influence of such buoyancy is described, for example, in Document 2 below.

  (Reference 2) Toshima, Okajima, Watanabe, Kazama: Simulation of temperature distribution in hot water storage tank of multifunction heat pump water heater, Proceedings of Academic Lectures of Society of Air Conditioning and Sanitation Engineering, 2004.9, pp. 69-72

The outline is described below.
FIG. 3 shows a calculation model of the temperature distribution in the hot water storage tank. In the model, hot water in the tank is divided into small sections of 1 to n layers in order from the top. Each divided layer is assumed to be a completely mixed layer, and the temperature of each layer is obtained by successively solving Formula (1), which is a thermal energy balance equation, for each layer at regular time intervals.
The thermal energy balance equation in the j layer is expressed by the following equation.

ここで、
ρ［ｋｇ／ｍ³］：水密度、Ｃｐ［Ｊ／ｋｇＫ］：水比熱、Ｖ［ｍ³］：タンク容積、Ｔ［Ｋ］：温度、ｔ［ｓ］：時間、Ｇｈ［ｍ³／ｓ］：加熱ポンプ流量、Ｇｂ［ｍ³／ｓ］：追焚きポンプ流量、Ｇｆ［ｍ³／ｓ］：床暖ポンプ流量、Ｇtop［ｍ³／ｓ］：上部出湯流量、Ｇmid［ｍ³／ｓ］：中温水出湯流量、Ｋ［Ｗ／ｍ²Ｋ］：タンク熱通過率、λ［Ｗ／ｍＫ］：熱伝導率、Ａｔ［ｍ³］：タンク断面伝熱面積、Ａｊ［ｍ³］：ｊ層タンク側面伝熱面積、Ｔａ［Ｋ］：外気温度、ｄ［ｍ］：タンク分割高さ
である。

here,
ρ [kg / m ³ ]: Water density, Cp [J / kgK]: Water specific heat, V [m ³ ]: Tank volume, T [K]: Temperature, t [s]: Time, Gh [m ³ / s ]: Heating pump flow rate, Gb [m ³ / s]: Reheating pump flow rate, Gf [m ³ / s]: Floor warming pump flow rate, Gtop [m ³ / s]: Upper hot water flow rate, Gmid [m ³ / s ]: Medium hot water discharge flow rate, K [W / m ² K]: Tank heat passage rate, λ [W / mK]: Thermal conductivity, At [m ³ ]: Tank cross-sectional heat transfer area, Aj [m ³ ]: j layer tank side surface heat transfer area, Ta [K]: outside air temperature, d [m]: tank division height.

Each term on the right side of Equation (1) will be described.
Right-side first term: an inflow term to the j-th layer, which is represented by the sum of the flow rate x temperature difference from each surface.
Second term on the right side: This is a heat dissipation term from the tank side wall. Here, the heat transfer rate K is determined from the experimental results.
3rd term and 4th term on right side: Terms related to heat conduction between upper and lower layers adjacent to the jth layer.

  Here, when equation (1) is solved as it is, only the local water temperature where the inflow from the tank side surface changes as shown in FIG. 4 (b) changes, which is different from the actual phenomenon (see FIG. 4 (a)). Result. This is due to the way of solving the upper and lower interlayer heat conduction terms in the third and fourth terms on the right side. In solving equation (1), the influence of buoyancy caused by the density difference due to the difference in water temperature is taken into account. It is necessary to solve the temperature diffusion. Therefore, in the third and fourth terms on the right side, the density of adjacent layers relative to the j layer is compared, and when buoyancy occurs, it is assumed that the thermal conductivity of that layer has been improved. If the value of λ is set to a value λz that is larger than the thermal conductivity λw of normal water (referred to room temperature water), and there is no reversal in density (no influence of buoyancy), normal heat transfer of water Calculate with the rate λw. Here, the thermal conductivity λz when buoyancy occurs is determined from the experimental results.

Specifically, the calculation is as follows. Compared with the density [rho _j of j layer, the density of one on the j-1-layer [rho _j-1, and the density [rho _{j + 1} of one of a j + 1 layer,
When ρ _j-1 > ρ _j λ _j-1 = λz [W / mK]
When _{ρ j-1 ≦ ρ j λ} j-1 = λw [W / mK]
When ρ _j > ρ _{j + 1} λ _{j + 1} = λz [W / mK]
When ρ _j ≦ ρ _{j + 1} λ _{j + 1} = λw [W / mK]
Based on the above assumption, temperature diffusion can be solved simply by simulating buoyancy without directly solving the flow in the tank.

  In the present embodiment, the calculation of the formula (1) is performed by the control unit 10 to estimate the temperature distribution of hot water in the hot water storage tank 1 every moment. And when applying Formula (1) to an actual apparatus (actual machine), in this Embodiment, the contents explained below are applied.

  In an actual apparatus, there are error factors such as a flow rate sensor error, a temperature sensor error, and a change in the tank heat passage rate due to the influence of sunlight and wind and rain. Therefore, even if the equation (1) is directly solved by an actual apparatus, an error occurs. If no correction is made, the error may accumulate and become a large error. In response to this, in the present embodiment, the hot water storage tank is provided with temperature sensors (also referred to as tank temperature sensors) 13a and 13b that measure and refer to the temperature of the hot water. At the positions of the tank temperature sensors 13a and 13b, the replacement process for replacing the temperature estimated values based on the equation (1) with the measured temperature values of the tank temperature sensors 13a and 13b is sequentially performed.

  FIG. 5 shows a conceptual diagram of sequential temperature correction, that is, a diagram showing a transition due to correction of the temperature distribution in the hot water storage tank. FIG. 5 shows the boiling operation of the hot water storage tank, and shows how time passes from left to right. In the figure on the left, there is a difference between the estimated temperature distribution (dashed line) and the actual value (solid line), but the hot water in the tank moves and passes the position of the temperature sensor (tank temperature sensor 13b) in the middle of the tank. As a result, the prediction error is corrected, and in the figure on the right where the error part has passed, it can be seen that the error is corrected and the estimated value and the actual value completely match. For this reason, even if an error occurs in the predicted temperature distribution value, the error portion can be corrected by passing through the position of the temperature sensor (tank temperature sensor 13b). Further, according to this correction method, even if the flow rate flowing through the tank cannot be accurately measured by the flow rate sensor and includes an error, the temperature distribution can be predicted with the error being minimized. The position of the temperature sensor (tank temperature sensor 13b) is ideally provided in an intermediate portion where the hot water in the tank passes frequently. In addition, if it is desired to improve the detection accuracy when the detection accuracy is important, for example, when the amount of remaining hot water is small, the detection accuracy of an arbitrary region can be improved by providing the detection accuracy in the lower part of the tank. Further, by providing a plurality of tank temperature sensors, the accuracy can be further improved.

  In FIG. 5, a temperature sensor (tank temperature sensor 13a) is also provided at the top of the tank. Regarding the temperature distribution of the hot water storage tank 1, the uppermost part of the tank is usually the hottest, and almost the same high temperature part is formed from the uppermost part of the tank to the temperature boundary layer position. When the heat storage amount in the hot water storage tank is estimated from the tank temperature distribution, the influence of the high temperature part becomes large, so that it is a problem to improve the prediction accuracy of the high temperature part.

  In this embodiment, in order to solve this problem, a tank temperature sensor 13a is provided at the uppermost part of the tank, and the temperature of the high temperature part (see FIG. 5) from the upper part of the tank to the temperature boundary layer position is linked to the temperature of the uppermost part of the tank. It is treated as something that changes. As a result, even if an error such as a deviation occurs in the predicted heat release to the air in the high-temperature part, which has a large effect on the heat storage amount prediction, the temperature is sequentially corrected, so the prediction accuracy of the temperature distribution and the heat storage amount prediction value is improved. It becomes possible to raise.

  A specific temperature correction method for the high temperature part will be described below. In the calculation method of Formula (1), the tank temperature estimated value in the divided section is calculated and updated from the upper side to the lower side. In this calculation, when the estimated tank temperature is higher than the water temperature (temperature measured value) of the tank temperature sensor 13a provided at the top of the tank (when temperature reversal occurs), the estimated tank temperature is the tank temperature. The estimated tank temperature value is replaced with the measured temperature value of the tank temperature sensor 13a until the temperature becomes lower than the measured temperature value of the sensor 13a. That is, it is assumed that all the temperatures in the high temperature part change at the same temperature.

  As an advantage of the above method, it is possible to cope with a temperature distribution change when low temperature water flows into the upper part of the hot water storage tank. The contents will be described below.

  FIG. 6 shows the rise change of the boiling temperature (heat exchanger outlet water temperature) from the start of the heat pump as a heating device. Since heat pumps have large heat capacities such as heat exchangers and compressors, they cannot be instantaneously started up at a high boiling temperature, and when starting, the boiling temperature tends to gradually rise as shown in FIG. Until reaching A in FIG. 6, water having a temperature lower than the boiling setting temperature, that is, the temperature at the top of the hot water storage tank flows. When the low-temperature water flows into the upper part of the hot water storage tank 1 in this way, the high-temperature water in the high-temperature part is cooled, and the water temperature in the high-temperature part decreases as a whole. This phenomenon is unavoidable when a heating device that is difficult to instantly raise the boiling temperature, such as a heat pump type, is unavoidable, and this phenomenon occurs every time the heat pump is started. For this reason, in order to improve the hot water tank temperature distribution prediction accuracy, it is necessary to cope with this phenomenon. According to the high temperature part temperature correction method of the present embodiment described above, in order to sequentially update the water temperature of the high temperature part based on the temperature measurement value of the tank temperature sensor 13a in the upper part of the tank when low temperature water flows in, the heat pump Therefore, it is possible to correct an appropriate temperature distribution corresponding to the characteristics, and to improve the prediction accuracy.

  Subsequently, in the present embodiment, a calculation method when the medium-temperature water flows into the tank middle part will be described. The inflow of medium-temperature water is, for example, in the vicinity of the return pipe when adding a load-side heat exchanger (not shown) such as a floor heating operation or the like for operation of the bathtub tracking circuit in FIG. Occurs. In the calculation method according to the conventional formula (1) described above, when density inversion occurs in the upper and lower sides of adjacent divided layers with tanks (when the density of the upper layer is greater than the density of the lower layer) The thermal conductivity of water was calculated with a large value by simulating the buoyancy generated. In this embodiment, when applying an actual device, in order to reduce the calculation load on the actual device, the density calculation of water is eliminated, and only the temperature comparison between the upper and lower layers is possible. That is, the density of water tends to decrease almost monotonously with increasing temperature. Therefore, the relationship “high density = low temperature” is established. Therefore, the temperature of the upper and lower layers is compared, and if the temperature of the upper layer is lower than the temperature of the lower layer, it is determined that density reversal has occurred, and in this case, the thermal conductivity of water between the upper and lower layers By calculating as a large value, it becomes possible to accurately estimate the tank temperature distribution even when the medium-temperature water flows in, as in the conventional calculation method.

  The value of the heat transfer rate K used in the second term on the right side of the equation (1) is determined by a test, but in an actual apparatus, a difference may occur due to individual differences. As a coping method for this, in the present embodiment, the heat passage rate is based on the actual measurement from the difference between the measured temperature average values of the temperature sensors 12a to 12f, 13a, and 13b from the start point to the end point of a certain time zone and the average outside air temperature. K is calculated and corrected sequentially. As a result, it is possible to appropriately correct an error in the heat transfer rate K caused by an individual difference, a model difference, or an external condition difference of an actual device.

  In the bathtub remedy circuit formed between the hot water storage tank 1 and the bath remedy heat exchanger 15 shown in FIG. 1, the water pump and the pipe loss are always the same, so that even if the flow rate is treated as a fixed value, it is large. There is no hindrance. For this reason, the water flow rate during the operation of the remedy circuit may be obtained in advance by testing, and this value may be used in the temperature distribution prediction to omit the flow rate sensor 11d. As a result, the number of parts is reduced and the cost can be reduced.

In addition, when the first bath retreat operation is performed with an actual device, the required time from the start to the stop operation of the retreat operation, the amount of change in the heat storage amount calculated from the temperature distribution of the hot water storage tank during this time, and the bath A method may be used in which the flow rate is estimated from the average value of the inlet / outlet temperature difference on the hot water storage tank side of the heat exchanger 15 and this flow rate is used thereafter. Here, the memory flow rate is obtained by the following equation.
Mourning flow rate [kg / s] = Tank heat storage amount change [kJ] due to Mourning ÷ Mourning time [s]
÷ Average value of temperature difference between inlet and outlet of the heat exchanger [K]
÷ Specific heat of water [kJ / kg / K] (2)
In this way, by obtaining the amount of memorial heat from the actual measurement data of the actual device, it is possible to absorb individual differences of the actual device and accurately estimate the flow rate. Therefore, the accuracy of tank temperature distribution calculation can be increased.

  When the heat source unit B shown in FIG. 1 is a heat pump, it is possible to estimate the water flow rate of the heat pump water heating circuit flowing into the hot water storage tank 1 by functionalizing the heating capacity characteristic of the heat pump and storing it in the control unit 10. It becomes. The heating capacity of the heat pump can be expressed as a function of the outside air temperature, the inflow water temperature, and the boiling temperature that affect the operation characteristics of the heat pump (Patent Document 1). As a result, the flow sensor 11c can be deleted, and the cost reduction of the hot water supply system can be realized.

  Moreover, when the pump used for the water flow control of the heat source unit B is a DC power supply pump, it becomes possible to estimate the water flow rate from the correlation between the applied voltage and the water flow rate. Since the applied voltage is an output value from the control unit 10, the control unit 10 recognizes the applied voltage, and the water flow rate can be estimated by storing and applying the correlation equation to the control unit 10. As a result, the flow sensor 11c can be deleted, and the cost reduction of the hot water supply system can be realized.

A method of calculating the heat storage amount stored in the hot water storage tank 1 using the hot water storage tank temperature distribution calculated as described above will be described.
The amount of heat storage is obtained by the following equation.

ここで、
ρ［ｋｇ／ｍ³］：水密度、Ｃｐ［Ｊ／ｋｇＫ］：水比熱、Ｖ［ｍ³］：タンク分割区間の容積、Ｔｉ［℃］：タンク分割区間の温度、Ｔｃ［℃］：市水温度、ｉ：タンク分割区間番号、ｎ：タンク分割数
である。

here,
ρ [kg / m ³ ]: water density, Cp [J / kgK]: water specific heat, V [m ³ ]: volume of tank division section, Ti [° C.]: temperature of tank division section, Tc [° C.]: city Water temperature, i: tank division section number, n: number of tank divisions.

  As described above, by using the hot water storage tank temperature distribution obtained in the present embodiment, it is possible to calculate an accurate heat storage amount, and an accurate hot water storage tank heat storage amount can be known at any time. Thereby, it becomes possible to boil accurately according to the heat storage amount required at the time of boiling the hot water storage tank at midnight, and it is possible to contribute to energy saving because no extra boiling is performed. In addition, since an accurate amount of heat storage can be always grasped even during daytime hours, it is possible to accurately determine the time when additional boiling should be started when the amount of heat storage is insufficient. As a result, it is possible to prevent inconvenience such as running out of hot water due to the delay in starting the boiling operation.

It is a block diagram of the hot water storage type hot water supply apparatus which concerns on Embodiment 1 of this invention. It is a schematic block diagram of the control system of the hot water storage type hot water supply apparatus. It is a calculation model figure of the temperature distribution in a hot water storage tank. It is the figure which represented the change of the temperature distribution in a hot water storage tank in the case of the inflow from a tank side surface comparing an actual and a calculation result. It is a figure showing transition by correction of temperature distribution in a hot water storage tank. It is a figure showing the rising change of the boiling temperature of a heating source.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Hot water storage tank, 2a General hot water supply side mixing valve, 2b Bath hot water supply side mixing valve, 3 Pressure reducing valve, 4 Solenoid valve, 5 Bathtub, 6 Mixing plug, 7 Remote control, 10 Control part, 11a, 11b, 11c, 11d 12a, 12b, 12c, 12d, 12e Temperature sensor, 13a, 13b Temperature sensor (tank temperature sensor), 14a, 14b, 14c Water pump, 15 Bath recuperation heat exchanger, 16 Temperature sensor, 20 Thermal insulation, 30 Exterior case , A Hot water storage unit, B Heat source unit, C Load side circuit.

Claims (12)

A hot water storage tank,
Heating means for heating hot water in the hot water storage tank;
A load side circuit for supplying hot water from the hot water storage tank to the load side;
A temperature sensor for measuring the temperature of hot water flowing into the hot water storage tank;
A flow rate sensor for measuring the flow rate of hot water flowing into the hot water storage tank;
A temperature sensor for detecting the outside air temperature;
Based on the temperature measurement value of the temperature sensor and the flow rate measurement value of the flow sensor, the temperature of each layer divided into a plurality of layers in the hot water storage tank in the vertical direction, the inflow heat amount from the pipe connected to each layer, A temperature distribution calculating means for calculating from the sum of the amount of heat released based on the difference between the temperature of each layer and the outside air temperature and the amount of heat transferred to the layers adjacent to each layer vertically;
A hot water storage type hot water supply apparatus characterized by comprising: It has a tank temperature sensor that measures the temperature of the hot water storage tank,
The temperature distribution calculating means includes
The hot water storage type hot water supply apparatus according to claim 1, wherein the temperature distribution calculation result of each layer is compared with the temperature measurement value of the tank temperature sensor, and the temperature distribution calculation result is sequentially corrected.   The hot water storage type hot water supply apparatus according to claim 2, wherein a tank temperature sensor for measuring the temperature of the hot water storage tank is provided at least at the uppermost part of the hot water storage tank. The temperature distribution calculating means includes
When the tank temperature estimation value in the divided section is updated from the upper side to the lower side of the hot water storage tank, and the tank temperature estimation value is higher than the temperature measurement value of the tank temperature sensor provided at the top of the hot water storage tank The hot water storage according to claim 3, wherein the estimated tank temperature value is replaced with the measured temperature value of the tank temperature sensor until the estimated temperature value of the tank is lower than the measured temperature value of the tank temperature sensor. Water heater.   The thermal conductivity of water, which is a coefficient for calculating the amount of heat transfer between layers above and below each of the above layers, when the temperature of the upper layer is lower than the temperature of the lower layer, than the thermal conductivity of water at room temperature The hot water storage type hot water supply apparatus according to any one of claims 1 to 4, wherein the hot water storage apparatus has a large value.   The coefficient used for calculation of the heat release based on the difference between the temperature of each layer and the outside air temperature is corrected from the difference between the temperature average value of the temperature sensor for a predetermined time and the outside air temperature average value. The hot water storage type hot water supply apparatus according to any one of? A remedy heat exchanger for recognizing bath water, and a forward pipe and a return pipe for connecting the hot water storage tank and the remedy heat exchanger,
The hot water storage type hot water supply apparatus according to any one of claims 1 to 6, wherein the temperature distribution calculation means calculates the re flow rate as a fixed value.   The hot water storage type hot water supply apparatus according to claim 7, wherein a tank temperature sensor for measuring the temperature of the hot water storage tank is provided at least above a connection position of the return pipe.   8. A remedy flow rate estimating means for estimating a remedy flow rate from the amount of heat and time required for remedy and the average value of the temperature difference between the return and return to the remedy heat exchanger is provided. Or the hot water storage type hot-water supply apparatus of 8 or 8. The heating means is a heat pump;
The hot water storage type hot water supply apparatus according to any one of claims 1 to 9, further comprising a calculation means for estimating a water flow rate of a heat pump heating circuit from performance characteristics of the heating means. The heating means comprises a water pump;
The hot water storage type hot water supply apparatus according to any one of claims 1 to 10, further comprising a calculation means for estimating a water flow rate of the heating circuit from a water pump control value.   The hot water storage type hot water supply apparatus according to any one of claims 1 to 11, further comprising heat storage amount calculation means for calculating a heat storage amount in the hot water storage tank from a temperature distribution in the hot water storage tank.

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