JP2007198731A - Hot water storage type water heater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hot water storage type water heater, capable of reducing the electric power rate by performing efficient boiling-up in a predetermined time zone. <P>SOLUTION: The hot water storage type water heater comprises a hot water storage tank 110 for storing hot water to be supplied, a heat pump device 120 for heating water in the tank 110 into hot water, and a control device 130 for operation-controlling the heat pump device 120 in a predetermined time zone determined mainly according to power cost so that hot water in the tank 110 has a necessary boiling-up heating value Q per day. When the control device 130 determines that the tank 110 is not filled with hot water at the time of storing hot water of the necessary boiling-up heating value Q in the predetermined time zone at a predetermined boiling-up temperature Tp and a predetermined boiling-up flow rate, the control device changes at least either the predetermined boiling-up temperature Tp or the heating capacity of the heat pump device 120 so as to increase the predetermined boiling-up flow rate W to fill the tank 110 with hot water. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a hot water storage type hot water supply apparatus that stores hot water for hot water supply heated by a heat pump device in a hot water storage tank.

  As a conventional hot water storage type hot water supply apparatus, as shown in Patent Document 1, a heating means that heats hot water is provided with a heat pump heat collector and a solar heat collector. In this hot water storage type hot water supply apparatus, heat pumps are collected in a predetermined time period determined according to the electric power cost, for example, a late night time period (specifically, for example, from 23:00 on the current day to 7:00 on the next day) in which the electric charge is low in a lighting contract by time. Boil most of the hot water in the tank by operating the heater. In other daytime hours, hot water can be supplemented by operating solar collectors or heat pump collectors in addition to the shortage that was not boiled in midnight hours or the amount used in daytime hours. I try to boil it up.

JP 2002-195650 A

  However, it is best that the boiling of the hot water is completed in the midnight hours when the solar power collector and the heat pump collector are not operated during the daytime hours, and the power rate is low. Predetermined boiling may not be completed due to a decrease in the capacity of the heating means due to changes in usage amount, seasonal hot water temperature or outside air temperature. In such a situation, it is important how efficiently the amount of heat that can be boiled is obtained, but in Patent Document 1, there is no particular consideration for this point.

  In view of the above problems, an object of the present invention is to provide a hot water storage type hot water supply apparatus that can efficiently raise water in a predetermined time zone and reduce an electricity bill.

  In order to achieve the above object, the present invention employs the following technical means.

  According to the first aspect of the present invention, a hot water storage tank (110) for storing hot water for hot water supply therein, a heat pump device (120) for heating the water in the hot water storage tank (110) into hot water, and a hot water storage tank (110) Control for controlling the operation of the heat pump device (120) in a predetermined time period mainly determined according to the power cost so that the hot water in the hot water (Q) required for hot water supply in one day is provided. In the hot water storage type hot water supply apparatus including the device (130), the control device (130) sets the required amount of heating heat (Q) at a predetermined time zone at a predetermined boiling temperature (Tp) and a predetermined boiling flow rate (V). When hot water is stored, if it is determined that the hot water storage tank (110) is not filled with hot water, the predetermined boiling temperature (Tp) or the heat pump device (120) is increased so that the predetermined boiling flow rate (V) increases. And changing at least one of the heat capacity, it is characterized in that to satisfy with hot water to the hot water storage tank (110).

  As a result, if the amount of heat that can be stored in the hot water is the same even if the required amount of boiling heat (Q) cannot be ensured, the boiling temperature (Tp) should be lower than the predetermined value, and a larger amount of hot water should be stored. Since the heat pump device (120) can be operated at a higher energy efficiency (coefficient of performance) than storing a small amount of hot water, power consumption can be reduced.

  Further, by changing the heating capacity in the increasing direction, the boiling flow rate (V) can be increased and the hot water storage tank (110) can be filled with the required boiling heat quantity (Q). That is, boiling due to the operation of the heat pump device (120) outside the predetermined time period can be eliminated, and the electricity bill can be reduced as a whole.

  The invention according to claim 2 is characterized in that the controller (130) changes the boiling temperature (Tp) to a lower side as the outside air temperature (Ta) is lower.

  Thereby, the difference of the temperature (Tw) of the water which falls corresponding to outside temperature (Ta) and the boiling temperature (Tp) after a change can be made equivalent or small. Therefore, the heating capacity of the heat pump device (120) can be reduced to operate at a point with high energy efficiency (coefficient of performance), and power consumption can be reduced.

  The invention according to claim 3 is characterized in that the controller (130) changes the heating capacity to the higher side as the outside air temperature (Ta) is lower.

  Thereby, the heat storage amount of the hot water storage type hot water supply device (100) can be kept substantially constant with respect to the change in the outside air temperature (Ta).

  In the invention according to claim 4, the control device (120) has a predetermined boiling temperature (Tp) in a temperature region where the outside air temperature (Ta) causes frost formation in the heat absorption part (124) in the heat pump device (120). ) Is changed to a lower side, or the heating capacity is changed to a higher side.

  This makes it possible to efficiently raise water during frosting that hinders boiling.

  In addition, the code | symbol in the parenthesis attached | subjected to each said means shows the correspondence with the specific means of embodiment description later mentioned.

  Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a schematic diagram showing a schematic configuration of a hot water storage type hot water supply apparatus 100 of the present embodiment. The hot water storage type hot water supply device 100 mainly includes a hot water storage tank 110, a heat pump device 120, and a control device 130.

  The hot water storage tank 110 is a tank made of metal (for example, made of stainless steel) having excellent corrosion resistance, and a heat insulating material (not shown) is arranged on the outer peripheral portion, and keeps hot water for hot water supply for a long time. To be able to. The hot water storage tank 110 has a vertically long shape in consideration of space efficiency at the time of installation, and the tank capacity L thereof is 370 L so as to cover the amount of hot water supply in a general household. An introduction port 111 is provided on the bottom surface of the hot water storage tank 110, and an introduction pipe 141 for introducing tap water into the hot water storage tank 110 is connected to the introduction port 111. The introduction pipe 141 is provided with a thermistor 143a, and the thermistor 143a outputs temperature information of tap water flowing through the introduction pipe 141 to the control device 130 described later.

  On the other hand, a lead-out port 112 is provided at the uppermost part of the hot water storage tank 110, and a lead-out pipe 142 for leading out hot water in the hot water storage tank 110 is connected to the lead-out port 112. A tap water supply pipe 145 is connected to the outlet pipe 142, and a mixing valve 146 is disposed at a junction with the water supply pipe 145. The mixing valve 146 adjusts the opening area ratio (ratio of the opening degree on the hot water side communicating with the outlet pipe 142 and the opening degree on the water side communicating with the water supply pipe 145), so that the currant, shower, bath, etc. on the downstream side In addition, hot water and water are appropriately mixed to supply hot water.

  In addition, a cold water outlet 113 is provided at the lower part of the hot water storage tank 110 to let out the tap water supplied from the introduction pipe 141 into the hot water storage tank 110, and the upper part of the hot water storage tank 110 is provided in the hot water storage tank 110. A hot water inlet 114 through which hot water flows is provided. The cold water outlet 113 and the hot water inlet 114 are connected by a circulation circuit 147, and a pump 148 is provided on the circulation circuit 147 on the cold water outlet 113 side. A part of the circulation circuit 147 is connected to a water heat exchanger 122 in the heat pump device 120 described later.

  Further, a plurality of thermistors 143b are arranged on the outer wall surface of the hot water storage tank 110 at predetermined intervals in the vertical direction so that temperature information at each water level in the hot water storage tank 110 is output to the control device 130 described later. ing.

The heat pump device 120 is a heating means using, for example, CO ₂ as a refrigerant, and an outdoor heat exchanger 124 including an electric compressor 121, a water heat exchanger 122, an expansion valve 123, and a blower 125 is sequentially connected by a refrigerant pipe 126. Closed circuit. The electric compressor 121 is provided with an inverter 127, and the inverter 127 varies the electric power supplied to the electric compressor 121. In addition, an outdoor air temperature sensor 124a is provided on the upstream side of the air flow generated by the blower 125 of the outdoor heat exchanger 124, and the outdoor air temperature sensor 124a provides temperature information of the outdoor air flowing into the outdoor heat exchanger 124 to be described later. Output to the control device 130.

  The heat pump device 120 changes the temperature of the refrigerant to high temperature and high pressure by the electric compressor 121 and performs heat exchange with cold water (tap water) supplied from the hot water storage tank 110 in the water heat exchanger 122 to obtain a predetermined temperature (boiling up). The hot water is boiled in hot water having a temperature Tp (for example, 90 ° C.), and the hot water is stored in the hot water storage tank 110. The outdoor heat exchanger 124 absorbs heat from the outside air with respect to the refrigerant radiated by the water heat exchanger 122.

  The control device 130 mainly controls the operation of the electric compressor 121 and the pump 148. The controller 130 receives temperature information from the outside air temperature sensor 124a and temperature information from the thermistors 143a and 143b. Further, as shown in FIG. 2, the control device 130 stores in advance control characteristics indicating the relationship of the compressor rotational speed N of the electric compressor 121 to the outside air temperature Ta. This control characteristic assumes that the compressor rotational speed N increases from N1 to N2 as the outside air temperature Ta decreases from 43 ° C to -10 ° C.

  Then, the control device 130 varies the rotational speeds of the electric compressor 121 and the pump 148 based on the input information, control characteristics, and results obtained from various predetermined arithmetic expressions (described later), mainly in the midnight time zone. Boil the hot water at In addition, as described in the section of the prior art, the midnight time zone is a predetermined time zone determined according to the power cost, for example, a time zone in which the electricity rate is low in the electric lamp contract according to time zone. It corresponds to from 23:00 to 7:00 on the next day (in some cases, it may be from 22:00 to 8:00).

  Note that when hot water or the like (not shown) is opened and hot water is supplied, hot water is led out from the outlet 112 of the tank 110. Along with this, tap water is introduced from the inlet 111 to the lower part of the hot water storage tank 110. If it is determined that the hot water in the hot water storage tank 110 has become less than a predetermined amount of heat according to the temperature information at each water level from the thermistor 143b according to the hot water supply at this time, the hot water in the hot water storage tank 110 regardless of the midnight time zone. In order to increase the amount of heat obtained by a predetermined arithmetic expression, the heat pump device 120 is operated.

  In the present invention, the operation control of the electric compressor 121 and the pump 148 during boiling at midnight time is characterized, and the details thereof will be described in detail with reference to the flowchart shown in FIG.

  First, at 23:00, which is the start time of the midnight time zone, the outside air temperature Ta is grasped from the outside air temperature sensor 124a in step S100. In step S110, (1) calculation of the heating condition, (2) determination of the compressor speed N of the electric compressor 121, and (3) calculation of the boiling flow rate V are performed.

  In the calculation of the boiling condition (1), the required boiling heat amount Q of hot water required on the day and the required boiling time Ha necessary for obtaining this required boiling heat amount Q are calculated. Necessary boiling heat quantity Q is calculated by the following formula 1.

ここで、Ｌは貯湯タンク１１０のタンク容量（３７０Ｌ）、Ｌｚは２３時時点における貯湯タンク１１０内の残湯量であり、（Ｌ−Ｌｚ）は必要沸き上げ量となる。Ｔｐは沸き上げ温度、Ｔｗは水道水の平均給水温度である。

Here, L is the tank capacity (370L) of the hot water storage tank 110, Lz is the amount of hot water in the hot water storage tank 110 at 23:00, and (L-Lz) is the required boiling amount. Tp is the boiling temperature, and Tw is the average water supply temperature of tap water.

  The remaining hot water amount Lz is obtained from a temperature information at each water level of the thermistor 143b by a predetermined arithmetic expression. The boiling temperature Tp is set in the range of 65 ° C. to 90 ° C., and the initial value of this control is 90 ° C. The average water supply temperature Tw is a temperature obtained from the thermistor 143a.

  Further, the required boiling time Ha is calculated by the following formula 2.

ヒートポンプ定格能力Ｐはここでは４．５ｋｗのものとしている。尚、ヒートポンプ装置１２０の室外側熱交換器１２４に着霜を伴う温度条件、即ち外気温度Ｔａが５℃以下では、ヒートポンプ定格能力Ｐは０．８掛けとした３．６ｋｗとする。

Here, the heat pump rated capacity P is 4.5 kw. In addition, under the temperature condition accompanied by frost formation on the outdoor heat exchanger 124 of the heat pump device 120, that is, the outside air temperature Ta is 5 ° C. or less, the heat pump rated capacity P is set to 3.6 kW multiplied by 0.8.

  The compressor rotational speed N in (2) is determined as a value corresponding to the outside air temperature Ta using the control characteristics described in FIG.

  The boiling flow rate V of {circle around (3)} is calculated by the following mathematical formula 3.

そして、ステップＳ１２０で沸き上げ流量Ｖ×深夜時間（８時間）は、必要沸き上げ量（Ｌ−Ｌｚ）より大きいか否かを判定する。即ちこれは、深夜時間（８時間）のうちに必要沸き上げ量（Ｌ−Ｌｚ）の沸き上げを完了して貯湯タンク１１０内を満タンにできるか否かを意味する。

In step S120, it is determined whether or not the boiling flow rate V × midnight time (8 hours) is greater than the required boiling amount (L-Lz). That is, this means whether the boiling of the required boiling amount (L-Lz) can be completed within midnight (8 hours) and the hot water storage tank 110 can be filled up.

  If an affirmative determination is made in step S120, the boiling start time is set by going back the required boiling time Ha from 7 o'clock, which is the end time of the midnight time zone in step S130, and boiling starts when that time comes. .

  However, if NO is determined in step S120, the required amount of boiling (L-Lz), that is, the required amount of heating Q cannot be obtained in the midnight time zone, and the setting of the boiling temperature Tp is determined in step S140. Decrease by the fixed amount α, and return to step S110 again. Lowering the boiling temperature Tp means increasing the flow rate of tap water flowing through the water heat exchanger 122 (circulation circuit 147), and here, the rotational speed of the pump 148 is increased.

  When the boiling temperature Tp is lowered, in the calculation in step S110, the required boiling heat amount Q is reduced, the required boiling time Ha is shortened, and the boiling flow rate V is increased. Then, by repeating step S140 and step S110, in step S120, although the boiling temperature Tp is lower than the initial 90 ° C., a condition for satisfying the required boiling amount (L-Lz) in 8 hours is set. In S130, boiling is started.

  Accordingly, if the amount of heat that can be stored in the hot water is the same even if the required amount of heat Q can not be secured, the boiling temperature Tp should be lower than the initial value (90 ° C.), and a larger amount of hot water should be stored. Since the heat pump device 120 can be operated at a point of higher energy efficiency (coefficient of performance) than storing a small amount of hot water (FIG. 4), the power consumption can be reduced and the electricity bill can be reduced.

  Moreover, the heating capability of the heat pump apparatus 120 can be kept substantially constant by increasing the compressor rotation speed N in accordance with the decrease in the outside air temperature Ta.

  Furthermore, in this control, since the hot water storage tank 110 is filled up and heated every day, the internal hot water is sequentially renewed and can be used hygienically.

(Second Embodiment)
A second embodiment of the present invention is shown in FIG. In the second embodiment, when it is determined in step S121 that the boiling flow rate V × midnight time (8 hours) is less than the required boiling amount (L-Lz) in step S121. In S150, the compressor rotational speed N is increased by a predetermined amount β.

  When the compressor rotation speed N increases, the refrigerant flow rate increases and the heating capacity of the heat pump device 120 increases. When the heating capacity is increased, the required boiling time Ha is shortened, and the boiling flow rate V per hour is increased. By repeating Step S150 and Step S110, the required amount of boiling (L-Lz) is set to 8 hours in Step S121. In step 130, boiling is started. Note that when the compressor rotational speed N is increased, N2 is set as the upper limit as described with reference to FIG. 2, and the determination is made in step S121.

  Thereby, the boiling flow rate V can be increased, and the hot water storage tank 110 can be filled with the required heating heat quantity Q, so that boiling by the operation of the heat pump device 120 outside the midnight time zone can be made unnecessary. Electricity charges can be reduced. Moreover, when the use of electric power is a contract only for midnight hours, there is no shortage of hot water and the hot water does not run out.

  Moreover, since the operation of the electric compressor 121 corresponding to the required amount of boiling (L-Lz) is performed, noise is not unnecessarily deteriorated and energy efficiency is not reduced.

(Other embodiments)
In the first and second embodiments, it has been described that the boiling temperature Tp (the rotational speed of the pump 148) and the compressor rotational speed N are individually changed. However, in the control of the present invention, both It is good also as what changes together.

  The outdoor air temperature Ta is determined in a wide range from a low temperature to a high temperature. However, it is usually difficult to ensure the required boiling amount (L-Lz). The outdoor heat exchanger 124 of the heat pump device 120 is difficult. Is a temperature region where frost formation occurs (specifically, a region of 5 ° C. or lower). Therefore, the control of the present invention is suitable for application to the temperature region where frost formation occurs, and efficient boiling is possible. It becomes.

It is a schematic diagram which shows schematic structure of the hot water storage type hot-water supply apparatus in embodiment of this invention. It is a control characteristic figure which shows the number of rotations of the compressor to outside air temperature. It is a flowchart which shows the boiling control in 1st Embodiment. It is a graph which shows the energy efficiency with respect to boiling temperature. It is a flowchart which shows the boiling control in 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Hot water storage type hot water supply apparatus 110 Hot water storage tank 120 Heat pump apparatus 124 Outdoor heat exchanger (heat absorption part)
130 Controller

Claims (4)

A hot water storage tank (110) for storing hot water for hot water supply inside,
A heat pump device (120) for heating the water in the hot water storage tank (110) to form the hot water;
The heat pump device (120) in a predetermined time period mainly determined according to the power cost so that the hot water in the hot water storage tank (110) has a necessary heating amount (Q) required for hot water supply for one day. A hot water storage hot water supply apparatus comprising a control device (130) for controlling the operation of
The controller (130) is configured to store the hot water storage tank (110) when storing the required boiling heat quantity (Q) at a predetermined boiling temperature (Tp) and a predetermined boiling flow rate (V) in the predetermined time period. ) When it is determined that the inside is not filled with the hot water, at least one of the predetermined boiling temperature (Tp) or the heating capacity of the heat pump device (120) is changed so that the predetermined boiling flow rate (V) increases. Then, the hot water storage type hot water supply apparatus is characterized in that the hot water storage tank (110) is filled with the hot water.   The hot water storage hot water supply apparatus according to claim 1, wherein the controller (130) changes the boiling temperature (Tp) to a lower side as the outside air temperature (Ta) is lower.   The hot water storage type hot water supply apparatus according to any one of claims 1 and 2, wherein the control device (130) changes the heating capability to a higher side as the outside air temperature (Ta) is lower.   The control device (120) changes the predetermined boiling temperature (Tp) to a lower side in a temperature region where the outside air temperature (Ta) causes frost formation in the heat absorption part (124) in the heat pump device (120). Or the said heating capability is changed to the high side, The hot water storage type hot-water supply apparatus in any one of Claims 1-3 characterized by the above-mentioned.

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