JP5975427B2 - Hot water supply device and hot water storage type hot water supply system provided with the same - Google Patents

Description

  The present invention relates to a hot water supply device such as a gas hot water supply device, and a hot water storage hot water supply system including the same.

Conventionally, a water heater 9 having a structure as shown in FIG. 4 is widely known. The hot water supply device 9 recovers heat from combustion gas generated by the burner 90 using a heat exchanger 91 and performs hot water heating. An incoming water temperature sensor Sa, a flow rate sensor Sb, and a tapping temperature sensor Sc are provided on the upstream side and the downstream side of the heat exchanger 91.
In such a hot water supply device 9, the combustion amount control of the burner 90 is executed as a means for setting the tapping temperature to a desired target tapping temperature. Conventionally, the control as shown in the block diagram of FIG. It is considered as a system.
In this control system, the feed forward combustion amount (FF combustion amount) (t) determined from the incoming water temperature θ _in (t), the target outgoing hot water temperature θ _sv (t), and the flow rate q (t), and the outgoing hot water temperature θ The sum of feedback combustion amount (FB combustion amount) (t) for adjusting _out (t) to the target hot water temperature θ _sv (t) is calculated.
(FF combustion amount) (t) is (FF combustion amount) (t) = (θ _sv (t) −θ _in (t)) · q (t).
Here, in the control system described above, most of the combustion amount of the burner 90 is occupied by the FF combustion amount. Therefore, it is important to make the value of the FF combustion amount appropriate in order for the control system to function properly.

  However, in the past, as described below, there is still room for improvement.

The incoming water temperature sensor Sa is provided away from the heat exchanger 91 on the upstream side in the water flow direction. For this reason, it takes time until the hot water whose temperature has been detected at the position of the incoming water temperature sensor Sa reaches the heat exchanger 91 and starts to be heated, resulting in a time lag. In the latent heat recovery type hot water supply apparatus, since the heat exchange part for latent heat recovery is provided upstream of the heat exchange part for sensible heat recovery that is strongly heated by the burner, the time lag is large.
However, conventionally, when calculating the FF combustion amount, the time lag as described above is not taken into consideration at all. For this reason, the value of the FF combustion amount cannot be asserted as the optimum value for controlling the tapping temperature to the target temperature. If the time lag is large, the tapping temperature is changed when the incoming water temperature changes greatly. The phenomenon that changed greatly.
On the other hand, when water is introduced into the hot water supply device 9 from the water pipe, the temperature of the incoming water does not change suddenly. However, for example, when water is supplied from the hot water storage tank to the hot water supply device 9, There are relatively many cases where the incoming water temperature changes suddenly. Therefore, in such a case, it is particularly necessary to prevent the phenomenon described above.

  As a means for suppressing the above-mentioned problems, data of a change in the incoming water over time is sequentially stored in a memory so as to correspond to the time lag described above, and when calculating the FF combustion amount, the memory It is conceivable that predetermined correspondence data is read from the data stored in. However, if such a means is adopted, there is a disadvantage that a large amount of memory is consumed.

Japanese Patent No. 3386575

  The present invention has been conceived under the circumstances described above, and reduces the amount of change in the hot water temperature when the incoming water temperature changes greatly without causing a problem of consuming a large amount of memory. An object of the present invention is to provide a hot water supply device capable of promoting stabilization of the hot water temperature and a hot water storage type hot water supply system including the hot water supply device.

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

The hot water supply apparatus provided by the first aspect of the present invention includes a burner and a heat exchanger that recovers heat from the combustion gas generated by the burner, and the water flow rate and water input to the heat exchanger are provided. A hot water supply apparatus configured to periodically execute a process of calculating a combustion amount of the burner based on a temperature and a target hot water temperature, and to perform drive control of the burner, and is used for calculating the combustion amount As the incoming water temperature, a filtered incoming water temperature is used, and this filtered incoming water temperature is based on the actual incoming water temperature detected using the incoming water temperature sensor and the filtered incoming water temperature used in the previous combustion amount calculation. It is the temperature calculated, Comprising: It is the temperature prescribed | regulated so that the value may change corresponding to the said water flow rate.
Preferably, the heat exchanger includes a sensible heat recovery heat exchange section heated by the burner, and a latent heat recovery heat exchange section located upstream of the heat exchange section in the water flow direction. It is said.

  The hot water storage type hot water supply system provided by the second aspect of the present invention includes a hot water storage tank and an auxiliary heat source device capable of heating hot water sent from the hot water storage tank to a predetermined outlet. In the hot water storage type hot water supply system, the hot water supply device provided by the first aspect of the present invention is used as the auxiliary heat source machine.

  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 system provided with the hot water supply apparatus which concerns on this invention. It is explanatory drawing which shows the specific example of the filtered incoming water temperature used for calculation of a combustion amount. It is a simulation figure which shows the specific example of the change of tapping temperature with respect to the change of the amount of incoming water. It is explanatory drawing which shows an example of the conventional hot water supply apparatus typically. It is a block diagram which shows the control system of the conventional hot water supply apparatus.

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

A hot water storage type hot water supply system SY shown in FIG. 1 includes a hot water storage tank 1, a hot water supply device WH as an auxiliary heat source machine, and a control unit 2. The hot water storage tank 1 stores hot water heated by, for example, a heat pump (not shown) as a main heat source device, and when the circulation pump P1 is driven, the hot water in the hot water storage tank 1 is heated via the piping 30a. Then, it is returned to the upper part in the hot water storage tank 1 through the piping part 30b and flows in. A water inlet pipe 31 and a hot water outlet pipe 32 are also connected to the lower part and the upper part of the hot water storage tank 1, and when a hot water tap (not shown) connected to the hot water outlet 32a of the hot water outlet pipe 32 is opened, the water inlet 31a is opened. The hot water in the hot water storage tank 1 flows out toward the hot water outlet 32a and is supplied to the hot water tap.

  The hot water supply device WH is used to heat hot water flowing out of the hot water storage tank 1 when the hot water temperature in the hot water storage tank 1 is lower than the target hot water supply temperature, for example. This hot water supply device WH has a structure similar to, for example, an existing gas instantaneous water heater, and has a burner 40, a fan 41, and a heat exchanger 42 that recovers heat from combustion gas generated using the burner 40. ing. The heat exchanger 42 is a so-called latent heat recovery type having heat exchange parts 42a and 42b for sensible heat recovery and latent heat recovery. Piping portions 33a and 33b for entering and leaving hot water into the heat exchanger 42 are connected to the hot water discharge pipe 32 of the hot water storage tank 1, and the hot water in the hot water storage tank 1 is exchanged by switching the three-way valve V1. It is possible to make it go to 42 and to make it go to the hot water outlet 32a after heating. In addition, the point which has the incoming water temperature sensor Sa, the flow sensor Sb, and the tapping temperature sensor Sc is the same as that of the hot water supply apparatus 9 demonstrated in FIG.

  The control unit 2 is configured by using, for example, a microcomputer, and in addition to executing the operation control of each part of the hot water storage type hot water supply system SY, it also executes the hot water temperature control of the hot water supply device WH. In this hot water temperature control, the combustion amount of the burner 40 (described in the background art) is based on the data from the incoming water temperature sensor Sa and the flow rate sensor Sb and the data of the target hot water temperature of the hot water supply device WH set using a remote controller or the like. The amount of combustion corresponding to the amount of FF combustion, and hereinafter referred to as FF combustion amount as appropriate). Specific contents of this processing will be described below.

  The control unit 2 samples the various data described above at a predetermined cycle n and performs operation control. The period n is 0.1 seconds, for example. In view of the case of actual control, in the following description, a function of the control period n is used instead of the function of time t.

First, the target hot water temperature θ _sv (n), the actual incoming water temperature data θ _in (n), and the data of the incoming water flow rate q (n) of the heat exchanger 42 are sampled at a period n and are acquired by the control unit 2. The actual incoming water temperature data θ _in (n) is the latest incoming water temperature data detected using the incoming water temperature sensor Sa.
Accordingly, the time lag L is determined as a function L (q (n)) of the incoming water flow rate q (n). Here, the time lag L corresponds to the time lag described in the section of the background art, and until the hot water supplied to the hot water supply device WH passes through the incoming water temperature sensor Sa and reaches the entrance of the heat exchanger 42. It corresponds to the required time. Therefore, the time lag L is closely related to the incoming water flow rate q (n). Basically, if the incoming water flow rate q (n) increases, L (q (n)) decreases. As a method for determining the time lag L, a formula for calculating the time lag L is prepared in advance and then obtained by calculation, or a data table indicating the relationship between the time lag L and the incoming flow rate q (n) by performing a test in advance. It is possible to adopt a technique such as creating it. As an example of a formula for calculating the time lag L, L = A (q (n) ² ) + B (q (n)) + C (where A to C are constants) may be mentioned. This equation captures that the time lag L changes in a quadratic function with respect to the change in the incoming water flow rate q (n). In the equation, the values of A to C may be obtained by experiments so as to be appropriate values.

Next, the filtered incoming water temperature θ ′ _in (n) is obtained using the following equation 1.

θ ′ _in (n) = (L / L + 1) · θ ′ _in (n−1) + (1 / L + 1) · θ _in (n) Equation 1

Here, θ ′ _in (n−1) is the filtered incoming water temperature used in the previous calculation of the combustion amount. θ _in (n) is the actual incoming water temperature data described above.

After obtaining the filtered water inlet temperature θ ′ _in (n), the burner 40 is calculated using the following equation (2).
FF combustion amount (n) is obtained.

FF combustion amount (n) = (θ _sv (n) −θ ′ _in (n)) · q (n) Equation 2

At the time of controlling the hot water temperature of the hot water supply device WH, the hot water temperature control is executed using the value of the FF combustion amount (n) obtained by Expression 2. The control system for the tapping temperature of the hot water supply device WH is the data corresponding to the FF combustion amount (n) calculated by the equation 2 instead of the transfer function G _FF (s) in the control system shown in FIG. Is replaced with a transfer function that outputs.

  Next, the operation of the hot water storage type hot water supply system SY will be described.

First, as described above, the FF combustion amount of the burner 40 is calculated using the equation 2. The equation 2 includes the filtered incoming temperature θ ′ _in (n) as a parameter. Here, the filtered incoming water temperature θ ′ _in (n) uses the previous value θ ′ _in (n−1) as a parameter, as shown in Equation 1. In addition, the time lag L is included in the parameter, and it is specified that the value of the filtered incoming water temperature θ ′ _in (n) increases as the time lag L increases. Therefore, when the incoming water flow rate is small and the time lag L is large, the filtered incoming water temperature θ ′ _in (n) is a value greatly affected by the past incoming water temperature.
By such a thing, when the actual incoming water temperature changes with a big width | variety, it is suppressed that the tapping water temperature changes with a big width | variety in connection with this. In addition, an effect of mitigating the sudden change in the FF combustion amount corresponding to the change in the actual incoming water temperature can be obtained. Such an effect is preferable in stabilizing the tapping temperature.

Further, in Equation 1, the coefficient of the actual incoming water temperature data θ _in (n) is (1 / L + 1), whereas the coefficient of the filtered incoming water temperature θ ′ _in (n) is larger (L / L + 1), and the filtered incoming water temperature θ ′ _in (n) is more weighted than the actual incoming water temperature data θ _in (n). For this reason, even if the actual incoming water temperature data θ _in (n) changes, it is further suppressed that the value of the filtered incoming water temperature θ ′ _in (n) fluctuates greatly.

FIG. 2 shows a specific example of the relationship between the filtered incoming water temperature θ ′ _in (n) calculated using Equation 1 and the actual incoming water temperature. In the figure, the incoming water flow rate q (n) and the time lag L are constant. In the figure, there is a great change in the actual incoming water temperature at the portion indicated by reference numeral a1. On the other hand, when the time lag L is 10 or 30, the filtered incoming water temperature θ ′ _in (n) changes behind the change in the actual incoming water temperature, and the change becomes gradual.

FIG. 3 shows a simulation result of the actual incoming water temperature and the outgoing hot water temperature when the FF combustion amount obtained by Equation 1 and Equation 2 is used, and the time lag L is 0, 10, 20, 30. It is shown. However, the time lag L = 0 corresponds to the conventional example. The flow rate q (n) and the time lag L are constant.
In the figure, the actual incoming water temperature is changing rapidly, and the hot water temperature is changing accordingly. However, overshoot H1 and H3 and undershoots D1 to D3 are smaller when time lag L = 10, 20, and 30, compared to overshoot H0 and undershoot D0 when time lag L = 0. Yes. In addition, an “annealing effect” is obtained in which sudden changes are alleviated. From such data, it can be understood that the tapping characteristics are greatly improved in the present invention.

Since the hot water supply device WH of the present embodiment is a latent heat recovery type, as described above, the time lag L is large. Moreover, since hot water is supplied from the hot water storage tank 1 to the hot water supply device WH, there is a high possibility that the actual incoming water temperature will change suddenly. Therefore, it is very meaningful to apply the above-described control to such a hot water supply device WH in order to improve the hot water discharge characteristic.
In addition, according to the control described above, it is possible to avoid a problem that a large amount of memory is consumed in order to obtain the FF combustion amount by calculation.

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

  As the calculation formula for the filtered water temperature and the calculation formula for the combustion amount, different formulas from Formula 1 and Formula 2 can be used. The filtered water temperature is basically the temperature calculated based on the actual water temperature detected using the water temperature sensor and the filtered water temperature used when calculating the previous combustion amount. Any temperature may be used as long as the value changes according to the incoming water flow rate to the vessel. Therefore, for example, the coefficients (L / L + 1) and (1 / L + 1) in Equation 1 can have different contents. For example, the combustion amount may be further corrected after it is calculated using Equation 2.

  The hot water supply apparatus according to the present invention can be other than the latent heat recovery type. The burner may be an oil burner instead of the gas burner. The hot water storage type hot water supply system according to the present invention may be of a type in which hot water heated by using exhaust heat of a fuel cell is stored in a hot water storage tank, for example, instead of the heat pump type.

As described above, according to the present invention, the adverse effect due to the time lag occurring between the incoming water temperature detection time and the incoming time to the heat exchanger is reduced, and when the incoming water temperature changes suddenly with a large fluctuation range, The effect of reducing the fluctuation range and mitigating rapid changes can be obtained. As a result, stable tapping characteristics can be obtained.
Such effects are, for example, a condition in which the temperature of the incoming water is likely to change suddenly when water is supplied from the hot water storage tank to the hot water supply device, and a condition in which the time lag is increased by the hot water supply device being a latent heat recovery type. Is particularly effective.

SY Hot water storage hot water system WH Hot water supply system Sa Water temperature sensor θ ' _in (n) Filtered water temperature 1 Hot water storage tank 2 Control unit 42 Heat exchanger

Claims (3)

A burner and a heat exchanger for recovering heat from the combustion gas generated by the burner,
A hot water supply apparatus configured to periodically execute a process of calculating a combustion amount of the burner based on an incoming water flow rate, an incoming water temperature, and a target hot water temperature to the heat exchanger, and to perform drive control of the burner. And
As the incoming water temperature used to calculate the combustion amount, a filtered incoming water temperature is used,
This filtered incoming water temperature is a temperature calculated based on the actual incoming water temperature detected using the incoming water temperature sensor and the filtered incoming water temperature used at the time of the previous combustion amount calculation. The hot water supply apparatus is characterized in that the temperature is defined such that the value thereof changes in response to. The hot water supply device according to claim 1,
The heat exchanger includes a heat exchange unit for recovering sensible heat that is heated by the burner, and a heat exchange unit for recovering latent heat that is located upstream of the heat exchange unit in the direction of water flow. . A hot water storage tank,
An auxiliary heat source machine capable of heating hot water sent from the hot water storage tank to a predetermined outlet,
A hot water storage hot water system comprising:
A hot water storage hot water supply system, wherein the hot water supply device according to claim 1 or 2 is used as the auxiliary heat source machine.

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