JPH0968369A - Heat pump hot-water supplier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To permit highly efficient hot-water reserving by a method wherein a calorific value, necessary for reserving hot-water, is operated and the optimum operating frequency is obtained from the operated necessary calorific value to operate a heat pump hot-water supplier with the obtained optimum operating frequency. SOLUTION: An inverter heat pump 1 is characterized so that the thermal efficiency of low-frequency operation is higher than that of high-frequency operation. Accordingly, the hot-water reserving temperature in a hot-water reserving tank 2 is detected by a temperature sensor 4 to operate the necessary calorific value for completing hot-water reservation by a microcomputer and the like and operate the lowest frequency of the inverter heat pump 1, which permits the finishing of hot-water reservation until a predetermined time, then, the lowest frequency becomes the optimum operating frequency, capable of operating the hot-water supplier with the maximum thermal efficiency. The hot-water supplier is operated continuously in the time band of midnight power with the lowest frequency (optimum operating frequency) whereby hot-water is reserved with a high efficiency compared with a case wherein hot-water is reserved by a constant output like as a conventional method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat pump water heater which can heat water in a hot water storage tank using a heat pump.

[0002]

2. Description of the Related Art A conventional heat pump water heater is shown in FIG. This is the hot water storage tank 101
The hot water inside is circulated to the heat pump 102, and the hot water inside the hot water storage tank 101 is stored while being heated with a uniform temperature distribution. With this heat pump water heater, when it is in the midnight electric power time zone, the hot water storage operation is started by the operation of the heat pump 102, the water in the hot water storage tank 101 is heated by the hot water storage heat exchanger 103, and the hot water storage tank 101 is heated by the effect of natural convection. While the inside is well mixed, the temperature is raised and the hot water is stored. The temperature sensor 104 detects that the hot water storage tank 101 is full, and ends the hot water storage.

[0003]

However, in the above-described conventional example, even if the amount of remaining hot water and the start time of hot water storage differ depending on the day, the inside of the heat pump 102 is not affected by the amount of remaining hot water and the hot water storage start time is early. Even when it is late, the hot water cannot be stored efficiently because it is operated at a constant output. The present invention has been made in view of this point, and an object of the present invention is to provide a heat pump water heater capable of realizing hot water storage with high efficiency.

[0004]

A heat pump water heater according to claim 1 of the present invention is a heat pump water heater comprising an inverter heat pump and a hot water storage tank, and temperature detecting means for each of the vertical layers in the hot water storage tank, A calculating means for calculating a necessary heat quantity based on the temperature detected by the temperature detecting means, a selecting means for obtaining an optimum operating frequency based on the necessary heat quantity calculated by the calculating means, and an operation at the optimum operating frequency obtained by the selecting means. And a control means for controlling.

Here, the optimum operating frequency means a frequency at which operation can be performed with the highest thermal efficiency. Since the inverter heat pump has a characteristic that the heat efficiency is higher when it is operated at a lower frequency than when it is operated at a high frequency, the lowest frequency is the optimum operation frequency. For example, in the case of continuous operation at the lowest frequency during the midnight power hours, the thermal efficiency is increased.

A heat pump water heater according to a second aspect of the present invention is the heat pump water heater according to the first aspect, in which hot water in the hot water storage tank is circulated to an inverter heat pump to heat water in the hot water storage tank, It is characterized in that the inside is mixed and the temperature is raised with a uniform temperature distribution to store hot water.

A heat pump water heater according to a third aspect of the present invention is the heat pump water heater according to the first aspect, wherein a hot water storage heat exchanger connected to an inverter heat pump is provided in the hot water storage tank to remove water in the hot water storage tank. It is characterized by heating, mixing the inside of the hot water storage tank, raising the temperature with a uniform temperature distribution, and storing the hot water.

A heat pump water heater according to a fourth aspect of the present invention is the heat pump water heater according to the first aspect, further comprising a temperature expansion valve for controlling the flow rate so that the outlet temperature of the inverter heat pump becomes a constant hot water storage temperature. Taking out low-temperature water from the lower part of the hot water storage tank, heating it with an inverter heat pump, returning the heated hot water to a constant hot water storage temperature to the upper part of the hot water storage tank, and storing hot water while forming a layer with a constant hot water storage temperature. It is a feature.

A heat pump water heater according to a fifth aspect of the present invention is the heat pump water heater according to the first aspect, further comprising an inverter pump for controlling a flow rate so that an outlet temperature of the inverter heat pump becomes a constant hot water storage temperature. Characterized by taking out low-temperature water from the lower part of the tank, heating it with an inverter heat pump, returning the heated hot water to a constant hot water storage temperature to the upper part of the hot water storage tank, and forming a layer with a constant hot water storage temperature. It is what

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. FIG. 1 is a configuration diagram of a heat pump water heater according to an embodiment of the present invention. As shown in FIG. 1, this heat pump water heater is a heat pump water heater including an inverter heat pump 1 and a hot water storage tank 2, and is detected by the temperature detecting means in each of the vertical layers in the hot water storage tank 2 and the temperature detecting means. A calculation means for calculating a necessary heat quantity based on the temperature, a selection means for obtaining an optimum operation frequency based on the necessary heat quantity calculated by the calculation means, and a control means for operating at the optimum operation frequency obtained by the selection means It is a thing.

Further, as shown in FIG. 1, in this heat pump water heater, a temperature sensor 4 is installed for each layer in the hot water storage tank 2 as temperature detecting means for each layer in the vertical direction.
The boundaries of the layers are indicated by broken lines in FIG. A microcomputer or the like is used as a calculating means for calculating the required heat quantity and a selecting means for obtaining the optimum operating frequency. The inverter heat pump 1 is installed as a control means for operating at the optimum operating frequency.

The required amount of heat is calculated by obtaining the temperature difference between the hot water storage temperature and the temperature detected by the temperature detection means for each level in the vertical direction in the hot water storage tank 2 and using this to calculate the specific heat of water, the water density and the hot water storage tank. The heat quantity required for each vertical floor in the hot water storage tank 2 is calculated by multiplying the volume of each vertical floor in 2 and the necessary heat quantity for each vertical floor in the hot water storage tank 2 is summed up. It is a thing. The above calculation is performed using a microcomputer or the like.

A method of selecting the optimum operating frequency is necessary based on the relationship between the heating capacity per unit time of the inverter heat pump 1 and the frequency in relation to the relationship between the inverter heat pump 1 and the hot water storage tank 2. The optimum operating frequency for obtaining the heating capacity of the inverter heat pump 1 per unit time is obtained. The above calculation is performed using a microcomputer or the like.

In this heat pump water heater, a hot water storage heat exchanger 3 connected to the inverter heat pump 1 is provided in the hot water storage tank 2 to heat the water in the hot water storage tank 2, and the hot water storage tank is subjected to natural convection or forced convection. The inside of 2 is mixed, the temperature is raised with a uniform temperature distribution, and hot water is stored. In this case, since the water in the hot water storage tank 2 is heated, it is sufficient to circulate the water in the hot water storage tank 2, and it is not necessary to circulate the water outside the hot water storage tank 2.

The heat pump water heater has a safety valve 9 on the hot water supply side, and the safety valve 9 is opened when the inside of the hot water storage tank 2 has a certain pressure or more. Further, the pressure reducing valve 10 is provided on the water supply side, and the pressure on the water supply side having a high pressure is reduced and used.

The method of using this heat pump water heater will be described below. For example, consider a case where hot water is used to store hot water at midnight. It is assumed that the midnight power hours are from 11:00 pm to 7:00 am. The user does not use hot water during the midnight power hours, and starts using the hot water at 7:00 am. In such a case, if the hot water storage start time is 11:00 pm and the hot water storage should be completed by 7 am, on a day with a small amount of remaining hot water, a large heating amount (inverter frequency is large) must be used for operation. Although hot water storage cannot be completed by the time, hot water storage can be completed by a predetermined time on a day with a large amount of remaining hot water even with a small heating amount (small frequency of the inverter).

By the way, the inverter heat pump 1 has a characteristic that the thermal efficiency is higher when it is operated at a low frequency than when it is operated at a high frequency.

Therefore, when the hot water storage temperature is detected by the temperature sensor 4, the amount of heat required to complete the hot water storage is calculated by a microcomputer, and the minimum frequency of the inverter heat pump 1 that can complete the hot water storage by a predetermined time is calculated,
The lowest frequency is the optimum operating frequency that allows operation with the highest thermal efficiency. By continuously operating in the midnight power time zone at the lowest frequency, hot water can be stored with high efficiency as compared with the case of storing hot water with a constant output as in the conventional example.

A method of calculating the necessary heat quantity, minimum frequency, etc. will be described below. If the required amount of heat is Q (kcal), Q is calculated by the formula shown in Table 1.

[0020]

[Table 1]

Table 1 shows that the hot water storage tank 2 is divided into n layers having the same volume in the vertical direction, the required amount of heat is calculated for each layer, and the required amount of heat is summed to obtain the required amount of heat Q (kcal).
Is to be calculated.

The first term in Table 1 is the required heat quantity of the first part from the top of the hot water storage tank 2 divided into n pieces. That is, [specific heat of water C × density of water ρ × (hot water storage temperature T _F −temperature T _{1 of the first} part from the top of the hot water storage tank 2) × hot water storage tank 2
Is the volume V / n] of the first part from the top.

Similarly, the second to nth terms are calculated and summed to calculate the required heat quantity Q (kcal).

When the heating capacity of the inverter heat pump 1 is QHP (kcal / hour), QHP = Q / hot water storage time is calculated. Furthermore, the heating capacity QHP (kcal / hour) and frequency (H
The relationship of z) is shown in FIG. FIG. 6 is a graph showing the relationship between the heating capacity QHP (kcal / hour) of the inverter heat pump 1 and the frequency (Hz). In FIG. 6, the vertical axis represents the heating capacity QHP (kcal / hour) of the inverter heat pump 1, and the horizontal axis represents the frequency (Hz). In the graph of FIG. 6, the frequency (Hz) corresponding to the heating capacity QHP (kcal / hour) of the inverter heat pump 1
This is the lowest frequency.

FIG. 2 is a block diagram of a heat pump water heater according to another embodiment of the present invention. This heat pump water heater is similar to the heat pump water heater of FIG. 1, but in this case, the hot water in the hot water storage tank 2 is circulated to the inverter heat pump 1 to heat the water in the hot water storage tank 2 to cause natural convection or forced convection. The difference is that the inside of the hot water storage tank 2 is mixed and the temperature is raised with a uniform temperature distribution to store hot water. Therefore, the heat exchanger 3 for storing hot water is not provided, but the circulation pump 6 is provided. Other configurations are the same as in the case of FIG. 1 and can be used in the same manner as in the case of FIG.

FIG. 3 is a block diagram of a heat pump water heater according to still another embodiment of the present invention. This heat pump water heater is similar to the heat pump water heater in FIG.
In this case, the temperature expansion valve 5 that controls the flow rate so that the outlet temperature of the inverter heat pump 1 is constant and reaches the hot water storage temperature.
Equipped with, take out low temperature water from the bottom of the hot water storage tank 2,
The point that the hot water heated by the inverter heat pump 1 and heated to a constant temperature is returned to the upper part of the hot water storage tank 2 to form a layer having a constant hot water storage temperature while expanding the layer from top to bottom to store hot water. different.

That is, since hot water having a constant hot water storage temperature always returns to the upper portion of the hot water storage tank 2, the hot water storage tank 2 always has a constant hot water storage even when the hot water storage operation is just started. Since there is hot water at the temperature, when hot water is used from the upper part of the hot water storage tank 2, hot water having a constant hot water storage temperature can be used even during hot water storage operation, and there is no concern of running out of hot water.

Further, the capillary 7 is installed in parallel with the temperature expansion valve 5. The role of the capillary 7 is to completely close the temperature expansion valve 5 and prevent water from passing when the temperature of the temperature sensing part is equal to or lower than the set temperature and the inverter heat pump 1 is in the heating operation. In such a state, water is heated by the inverter heat pump 1, and there arises a problem that the temperature sensing portion of the temperature expansion valve 5 cannot be detected even if the temperature rises above a certain temperature in the inverter heat pump 1. In such a case, by installing the capillary 7 in parallel with the temperature expansion valve 5, a minimum flow rate can be secured in the temperature sensing section, and the inverter heat pump 1
To prevent it from overheating. The hot water storage tank 2 is provided with several temperature sensors 4 in the vertical direction so that the hot water storage status can be seen.

Other configurations are the same as those in the case of FIG. 2 and can be used in the same manner as in the case of FIG.

FIG. 4 is a block diagram of a heat pump water heater which is still another embodiment of the present invention. This heat pump water heater is similar to the heat pump water heater of FIG. 3, but in this case, an inverter pump 8 is provided instead of the temperature expansion valve 5 and the capillary 7, and when the water in the hot water storage tank 2 is sent to the inverter heat pump 1, The difference is that the flow rate is controlled so that the outlet temperature of the inverter heat pump 1 becomes a constant hot water storage temperature. Other configurations are the same as in the case of FIG. 3 and can be used in the same manner as in the case of FIG.

As described above, the heat pump water heater of the present invention can provide a heat pump water heater which can store hot water with high efficiency.

[0032]

In the heat pump water heater according to the first aspect of the present invention, the optimum operating frequency of the inverter heat pump capable of storing the required amount of heat in a certain time with high thermal efficiency is calculated, and the inverter heat pump is operated at the optimum operating frequency. By doing so, hot water storage can be realized with high efficiency. It can also be used to efficiently store hot water by continuously operating it without raising the frequency during the midnight power hours.

In the heat pump water heater according to claim 2 of the present invention, in addition to the effect of the heat pump water heater according to claim 1, hot water is stored by mixing the inside of the hot water storage tank and raising the temperature with a uniform temperature distribution. can do. Further, since the water in the hot water storage tank is heated, it is sufficient to circulate the water in the hot water storage tank, and it is not necessary to circulate the water outside the hot water storage tank. In the heat pump water heater according to claim 3 of the present invention,
In addition to the effect of the heat pump water heater according to the first aspect, it is possible to mix the inside of the hot water storage tank and raise the temperature with a uniform temperature distribution to store the hot water.

In the heat pump water heater according to claim 4 of the present invention, in addition to the effect of the heat pump water heater according to claim 1, this layer is formed while forming a layer having a constant hot water storage temperature in the hot water storage tank. Since the hot water is expanded from the top to the bottom in the hot water storage tank, hot water with a constant hot water storage temperature can be used even during hot water storage operation.

In the heat pump water heater according to claim 5 of the present invention, in addition to the effect of the heat pump water heater according to claim 1, this layer is formed while forming a layer having a constant hot water storage temperature in the hot water storage tank. Since the hot water is expanded from the top to the bottom in the hot water storage tank, hot water with a constant hot water storage temperature can be used even during hot water storage operation. Furthermore, the structure of the heat pump water heater can be simplified.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a heat pump water heater according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a heat pump water heater according to another embodiment of the present invention.

FIG. 3 is a configuration diagram of a heat pump water heater according to still another embodiment of the present invention.

FIG. 4 is a configuration diagram of a heat pump water heater which is still another embodiment of the present invention.

FIG. 5 is a configuration diagram of a conventional heat pump water heater.

FIG. 6 is a graph showing the relationship between the heating capacity of an inverter heat pump and frequency.

[Explanation of symbols]

 1 Inverter heat pump 2 Hot water storage tank 3 Hot water heat exchanger 4 Temperature detection means 5 Temperature expansion valve 8 Inverter pump

Claims (5)

[Claims] 1. A heat pump hot water supply apparatus comprising an inverter heat pump and a hot water storage tank, wherein temperature detecting means for each layer in the vertical direction in the hot water storage tank, and calculation means for calculating a necessary amount of heat based on the temperature detected by the temperature detecting means. A heat pump water heater comprising: a selecting unit that obtains an optimum operating frequency based on the required heat quantity calculated by the calculating unit; and a control unit that operates at the optimum operating frequency obtained by the selecting unit. 2. The hot water in the hot water storage tank is circulated to an inverter heat pump to heat the water in the hot water storage tank, and the hot water in the hot water storage tank is mixed to raise the temperature with a uniform temperature distribution to store the hot water. The heat pump water heater according to claim 1. 3. A hot water storage heat exchanger connected to an inverter heat pump is provided in the hot water storage tank to heat water in the hot water storage tank, mix the hot water storage tank, and raise the temperature with a uniform temperature distribution to store hot water. The heat pump water heater according to claim 1, wherein 4. An inverter heat pump is provided with a temperature expansion valve for controlling the flow rate so that the outlet temperature becomes a constant hot water storage temperature, low temperature water is taken out from the lower part of the hot water storage tank, heated by the inverter heat pump, and heated to a constant temperature. 2. The heat pump water heater according to claim 1, wherein the hot water having the hot water storage temperature is returned to the upper portion of the hot water storage tank to store hot water while forming a layer having a constant hot water storage temperature. 5. An inverter heat pump is provided with an inverter pump for controlling the flow rate so that the outlet temperature of the inverter heat pump becomes a constant hot water storage temperature. 2. The heat pump water heater according to claim 1, wherein the hot water having the hot water storage temperature is returned to the upper part of the hot water storage tank and is stored while forming a layer having a constant hot water storage temperature.