JPS6030944A - Hot-water storage type hot-water supply device - Google Patents

Abstract

PURPOSE:To contrive to save the maintenance cost by a method wherein a hot-water supply device utilizing the midnight electric power service and a heat pump are combined with each other, and the heat pump is operated during the midnight time zone or operated only within the period of lower energy cost excluding the midnight time zone. CONSTITUTION:The open air temperature and the lower part temperature T1 of a hot-water storage tank 1 are detected by the open air temperature sensor 17 and a lower part temperature sensor 14 just after the starting of midnight electric power service time zone. Those temperature signals are inputted into a memory device 18 which stores the performance characteristics data of a heat pump device 3, then a heat pump heating up temperature T2 is obtained by a calculating part 21, while the temperature T2 is achieved by the heating with whole efficiency eta shown by eta>1. Further, the average performance Q of the heat pump required for heating of the lower part temperature T1 up to the heat pump heating up temperature T2 is obtained by a calculating part 22. Thereafter, the required time for heating up of the storage tank 1 is obtained by calculating parts 23, 24 and 25. When the obtained time is included within 8hr for midnight electric power service time, the time distribution is not required, accordingly, the heat pump device 3 is operated by the general electric power service simultaneously with the starting of the midnight electric power service. On the other hand, during the operation of the heat pump device 3, when the average performance of the heat pump is low due to the lower temperature of the open air, a heating body 2 is made energized by the midnight electric power service. The time presetting of above operation is made by a time distribution device 26.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hot water storage type water heater equipped with a heating element and a heat pump as a heat source.

A typical hot water storage type water heater is a water heater that uses late-night electricity. This water heater that uses late-night electricity is subject to the late-night electricity rate system for the purpose of increasing the electricity load during the night, and the electricity rate is cheaper than the electricity rate for general household use. It has secured a stable market due to its low maintenance costs, safety and hygiene, and other features. However, the discount rate for this electricity bill tends to be compressed, and the maintenance costs are becoming relatively high when compared with other heat source water heaters such as kerosene and gas.

On the other hand, heat pumps are widely used as air conditioners, but it is clear that if they are used as a heat source for water heaters on late-night electricity, it is quite advantageous in terms of maintenance costs.

However, the problems when using a heat pump alone as a heat source for a water heater are: (1) The capacity depends on the outside temperature, so it is possible to maintain a stable hot water temperature.
The amount of hot water cannot be secured.

(2) The temperature on the condenser side varies depending on the type of refrigerant, but there is not much difference, and the upper limit of the hot water temperature that can be obtained by heat exchange is 50
~55°C. For this reason, the hot water storage efficiency is lower than that of a water heater that uses late-night electricity, which stores hot water at about 85 degrees Celsius.

There were performance issues such as:

This 3! The new system combines a water heater that uses late-night electricity with a heat pump, and operates the heat pump only during late-night hours or other times when energy costs are lower. The objective is to provide a hot water storage type water heater that, when operated, takes advantage of the excellent features of a water heater that uses late-night electricity while improving maintenance costs. The present invention will be explained below based on the drawings.

FIG. 1 is a schematic diagram showing an embodiment of a hot water storage type water heater according to the present invention, in which 1 is a hot water storage tank, 2 is a heating element provided at the bottom of the hot water storage tank 1, 3 is a heat pump device, and 4 is a pressure pump device. m machine, 5 is a water-cooled condenser, 6 is an expansion valve, T is an evaporator,
8 is a suction pipe, 9 is a discharge pipe, and a water-cooled condenser 5. It is connected to the suction pipe 8 via the circulation pump IOY, and is connected to the lower side surface of the hot water storage tank 1, respectively. Reference numeral 11 denotes a water supply pipe connected to the lower side of the hot water storage tank 1. A hot water supply pipe 12 is connected to the upper part of the hot water storage tank 1, and a hot water tap 13 is provided at the tip of the hot water supply pipe 12.

Next, I will explain how it works. During boiling by the heat pump device 3, water sent from the lower part of the hot water storage tank 1 via the suction pipe 8 to the water-cooled condenser 5 by the operation of the circulation pump 1o is heated by the action of the heat pump device 3, and is then discharged. It returns to the hot water storage tank 1 via the pipe 9'4. By repeating this cycle, all the water in the hot water storage tank 1 is boiled. Even during boiling by the heating element 2, the heating element 2 is provided at the bottom of the hot water storage tank 1 and boils the entire water in the hot water storage tank 1. The hot water that has been boiled in this way is
By opening the pipe, the water source water enters the bottom of the hot water storage tank 1 through the water supply pipe 11, and the same amount of hot water is pushed up into the hot water supply pipe 12.
．． It is made available for use via the tap 13.

FIG. 2 is a control block diagram showing an example of control. Second
In the control diagram shown in the figure, 14 is the hot water storage tank 1.
15 is a remaining hot water amount sensor for detecting the amount of remaining hot water in the hot water storage tank 1; 16 is an upper temperature sensor for detecting the upper temperature in the hot water storage tank 1; be. 17 is an outside temperature sensor for detecting the outside temperature; 18 is a storage device into which characteristic data of the heat pump device 3 regarding the outside temperature, hot water temperature, and operating efficiency is input; and 19 is the temperature detected by each of the temperature sensors. It is an operation time setting device that sets the operation time of the heating element 2 and the heat pump device 3 based on the data in the storage device 18.
is a control device for operating the heating element 2 and the heat pump device 3 based on the time setting by the operating time setting device 19.

FIG. 3 is a block diagram showing details of the operating time setting device 19 shown in FIG. A calculation unit calculates the heat pump local temperature that can be heated by the heat pump device 3 based on the characteristic data of the heat pump device @3 stored in flt1B; 22 is a heat pump calculated by the calculation unit 21 for the heat pump device 3; A calculation section 23 calculates the average capacity of the heat pump when the operation reaches the local temperature, which is detected by the heat pump local temperature determined by the calculation section 21, the heat pump average capacity determined by the calculation section 22, and the remaining hot water amount sensor 15. Calculation unit that calculates the heat pump time from the amount of remaining hot water, 2
4 is the heat pump local temperature determined by the calculation unit 21, the remaining hot water amount detected by the remaining hot water amount sensor 15, and the upper temperature sensor 1.
6 is a calculation unit that calculates the heating time of the lower layer heating element from the detected upper temperature, and 25 is a calculation unit that calculates the heating time of the upper and lower heating elements from the upper temperature. 26 is the arithmetic unit 23 and the arithmetic unit 2
This is a time allocating device that allocates time based on the three local time periods calculated by the calculation unit 25 and the calculation unit 25.

Next, the operation will be explained with reference to the capacity vs. temperature diagram in FIG. 4 and the time vs. temperature diagram in FIG. 5.

Now, the total capacity of hot water storage tank 1 w V (lL 'A hot water amount'
vVt 74).

Lower temperature (T, guC), upper temperature v'rs ('c), rated boiling temperature w T,' (℃), heat pump discharge temperature F determined from the storage device 18 with reference to the outside air temperature and the lower temperature. l'T.

(℃), and the average capacity of the heat pump is Q (kcal
/hr), and the rated power consumption of the heating element 2 is assumed to be W (KW).

In Fig. 4, the vertical axis shows the intended capacity in the height direction of the hot water storage tank 1, and the horizontal axis shows the same temperature (corresponding to the height direction of the hot water storage tank 1); in the local state, the temperature T, (℃
) 'r is represented by a rectangle with the right side as A.

It is divided into four parts B, C, and D. Part A is the remaining hot water amount V
, (1) represents the residual hot water heat quantity consisting of the upper temperature 'r and ('c), and part B is the local distribution by the heat pump device 3, 0
The upper temperature is T! The heating element 2 boils the lower layer until it reaches ('C), and the local temperature is T.
, ('C) and then the heat dissipation causes T, (°C
) The heating element 2 is used to heat up the temperature that has dropped to .

Next, the operations of the storage device 18 and the operating time setting device 19 will be explained with respect to the model shown in FIG. Here, to simplify the explanation, we will first consider only the case of operation using late-night electricity. The heat pump device 3 is operated only when the ratio of the amount of heat obtained in the hot water storage tank 1, that is, the overall efficiency (η), to all the electrical inputs of the compressor, blower, and circulation pump of the heat pump device 3 is greater than 1.

First, the outside temperature sensor 17 immediately after entering the late-night power supply period.
and the outside temperature detected by the lower temperature sensor 14 and the following temperature T
, ('C) % - Input the characteristic data of the heat pump device 3 into the storage device 18 to determine that the overall efficiency η is η
〉1 heat pump discharge temperature T! ('C) in section 21, and further calculate the lower temperature T I (℃) as the heat pump discharge temperature IT!
Heat pump average capacity Q (kc) when returning home to (“C)
a l/hr) is determined by the Y calculation unit 22. Next, the calculation section 23
boils the lower layer (V V+ ) (1) of hot water storage tank 1 to the heat pump discharge temperature 'r, ('c) (
(Part B in Figure 4) is determined by the time H, '&.

The calculation unit 24 has the lower layer at the upper temperature T! It also includes the boiling time for boiling the lower layer with heating element 2 until it becomes the same as CC) (section C in Figure 4). Th'J,! Let the capacity of the heating element 2 be W (KWH). (I KWH=
860 kcal).

Further, the calculation unit 25 calculates the total capacity V (1) of the hot water storage tank 1.
This is to find the time HsY required to boil the water up to the rated boiling temperature T4 (the middle part of Figure 4).

CT, -Trixv H3= (time) X860 Demaru.

As described above, each required energization time H1゜H,,
Once H, the operating time is distributed by primary time division @, 26.

When the total time of H, ', -H,,H, respectively, falls within 8 hours of the late-night power supply time, time allocation is not performed, and the heat pump device 3 is operated with general power at the same time as the late-night power supply starts, When the detected value of the lower temperature sensor 14 reaches the heat pump discharge temperature T, the operation of the heat pump device 3 is stopped, and late-night power supply to the heating element 2 is started.

When the detected value of the upper temperature sensor 16 reaches the rated boiling temperature T4, the control device 20 cuts off the power supply to the heating element 2.
is activated. FIG. 5 is a heating characteristic diagram in which the temperature of the hot water storage tank 1 is plotted on the vertical axis and time is plotted on the horizontal axis, and the curve a-b-c-d is (H1+H,→-H3)=8 (.

FIG. 4 is a graph showing heating by the heat pump device 3 for the three portions shown in FIG. 4 between a and b. Furthermore, the area between b and c shows the heating by the heating element 2 targeting the part C in Fig. 4. Furthermore, the line between c and d shows heating by the heating element 2, which also targets part D in FIG. here,
The reason why the slopes between b and c and between C and C6 are different is because the amount of hot water to be boiled is different.

On the other hand, the outside temperature is low (heat pump average capacity Q (kcal)
/hr) is low, (Hs +Ht +us)
>8. In this case, if the heat pump device 3 heats up to the heat pump discharge temperature T2, the a-
As shown between f, it becomes impossible to reach the rated exhaust temperature T4 within the 8-hour late night energization period. For this reason, it is necessary to supply late-night power to the heating element 2 while the heat pump device 3 is in operation. The time allocation device 26 sets this time, and the simultaneous operation time H,)S1-S1-S1- for which the heat pump device 3 and the heating element 2'lt should be operated simultaneously is set as follows.・The time (H, +Hs) for heating parts C and D in Fig. 4 by the heating element 2 is a fixed value, and the time available for heating the parts C and D to the heat pump discharge temperature T2 is (s H2H,). Since it is time, QX (8-H2-H,) + WX860 XH.

= (T2-'rt) x (v-■+) This simultaneous operation time H4 applies. In this case, the operation is a-e in Figure 5.
As shown in the curves -b-c-d, the heat pump device 3 is in operation between a and b, and the heat pump device 3 is in operation between e and
and the simultaneous operation of the heating element 2. During b-c-6, the control device 20 operates to operate the heating element 2.

Although the above is a description of the case where late-night power is used, the present invention also operates the heat pump device 3 using general power during the day. That is, when the heat pump device 3 is operated using only late-night power as described above, the heat pump device 3 cannot be operated in the daytime when the outside temperature is high even though the coefficient of performance of the heat pump device 3 is higher than at night.

Therefore, in the present invention, the heat pump device 3 is operated using daytime general electricity if the energy cost is lower than using late-night electricity even if it uses daytime electricity, and this judgment is made. This is done in the control device 20.

FIG. 6 shows a 72m
It is a chart. In the figure, 0) to (5) indicate each step.

First, it is determined whether it is the midnight power supply time (1), and if it is the midnight power supply time, the heat pump device 3 and the heating element 2 are operated by the midnight power (2). On the other hand, if it is not the midnight power supply time in step (1), it is determined whether the system is in operation (y) (3). The operating state is when hot water is used. When the heat pump device 3 is in operation, the daytime energy cost ηd and the nighttime energy cost η are compared, and if ηd>ηゎ (4), the heat pump device 3 is operated by the general power source during the daytime. If not, return to step (1).

Here, the daytime energy cost ηd is Qa '1a-y.

It is indicated by. Qa is the daytime calorific value kcal/hr, Y4
] Shows the general electricity unit price of KWI (.

In addition, the nighttime energy cost η, is expressed as I1 7·=77, and Q is the nighttime calorific value kcal/hr, Yl
indicates the unit price of late-night electricity at IKWH.

This makes it possible to operate at a lower rate overall even when using general electricity, which is higher than late-night electricity.

In the above explanation, boiling is started by the heat pump device 3, but during late-night power operation, it is configured to operate only when the overall efficiency η is 1 or more as a prerequisite, and when the outside temperature is low. If the overall efficiency is 1 or less due to frost or the like, the heating element 2 may be configured to be energized from the beginning.

As explained in detail above, the hot water storage type water heater of the present invention detects outside air temperature and hot water temperature7, compares daytime energy cost and nighttime energy cost, and operates the heat pump device using cheap power. In addition, we designed the heat pump to operate in parallel with the heating element as needed using late-night electricity, making it possible to increase the operation rate of the heat pump, which has low maintenance costs, and further reduce costs. It has the advantage of being able to measure

[Brief explanation of drawings]

Fig. 1 is a schematic configuration diagram showing an embodiment of the hot water storage type water heater of the present invention, Fig. 2 is a control program diagram of the invention, and Fig. 3 is a diagram 1177 showing details of the operating time setting device. FIG. 4 is a diagram showing a specific example of this invention, FIG. 5 is a time vs. temperature diagram,
FIG. 6 is a tool for explaining the operation of an embodiment of this invention.
It is a chart. In the figure, 1 is a hot water storage tank, 2 is a heating element, 3 is a heat pump device, 14 is a lower temperature sensor, 15 is a remaining hot water amount sensor, 1
6 is an upper temperature sensor, 17 is an outside temperature sensor, 18 is a storage device, 19 is an operating time setting device, and 20 is a control device. Note that the same reference numerals in the figures indicate the same or similar parts. Agent Masuo Oiwa (2 others) Figure 1 Figure 2 Figure 2 Figure 4 Figure 4 Temperature ('C). Figure 5 layer

Claims (1)

[Claims] In a hot water storage type water heater equipped with a heat pump as a heat source and a heating element that uses late-night electricity, a lower temperature detection means for detecting the lower temperature of the hot water storage tank and a remaining amount of hot water for detecting the amount of remaining hot water in the hot water storage tank are provided. a detection means, an upper temperature detection means for detecting the upper temperature of the hot water storage tank, an outside temperature detection means for detecting the outside air temperature, and a storage device into which operation characteristics of the heat pump regarding the outside air temperature, the hot water temperature, and the operation efficiency are input. , an operation time setting means for late-night power, which sets the operation time of the heat pump and the heating element based on the detection values detected by the respective detection means and the operation characteristics stored in the storage device; During the power supply time, the operation is performed based on the time setting by the operation time setting means, and during the time period other than the midnight power supply time, the daytime energy cost when operating on general electricity and the cost when operating on late night electricity are calculated. A hot water storage type water heater characterized by being equipped with a control device that compares energy costs at night and operates according to the one with the lowest cost.