JP5385694B2 - Heat pump water heater - Google Patents

Description

  The present invention relates to a heat pump type water heater.

  Conventionally, in this type of heat pump water heater, a hot water storage tank for storing hot water and a hot water storage tank unit containing hot water supply functional parts, a compressor, a water heat exchanger, an expansion valve, and an air heat exchanger are annularly arranged. And a circulation circuit in which the water side of the water heat exchanger and the hot water storage tank are connected through a circulation pump and a flow sensor so that water can circulate.

  Then, the target flow rate of water is calculated from the incoming water temperature of the water to be heated, the target boiling temperature, and the rated heating capacity, and the rotation speed of the circulation pump is controlled so that the flow rate detected by the flow sensor becomes the target flow rate. The opening of the expansion valve is controlled so that the temperature of the refrigerant discharged from the refrigerant reaches the target refrigerant temperature, and the number of revolutions of the compressor is controlled to increase or decrease so that the outlet water temperature of the water heat exchanger becomes the target boiling temperature. The boiling operation was performed. (Patent Document 1)

JP 2007-327725 A

  By the way, in this conventional system, when the flow rate sensor is abolished for cost reduction, the heating operation can be performed by fixing the number of revolutions of the circulation pump according to the target flow rate. The flow resistance varies depending on the installation site due to the difference in piping length and height difference between tank units, and the flow rate changes. When the installation conditions change, the target rated heating capacity can be maintained simply by fixing the rotation speed of the circulation pump. There was a problem that could not be done.

In order to solve the above-described problems, the present invention provides a hot water storage tank unit in which a hot water storage tank for storing hot water is stored, a compressor, a water heat exchanger, a decompression means, and an evaporator in an annular shape. A heat pump unit having a heat pump cycle, a circulation circuit for connecting the hot water storage tank and the water heat exchanger so that water can be circulated by a circulation pump, and a boiling temperature sensor for detecting the outlet hot water temperature of the water heat exchanger And controlling the number of revolutions of the compressor so that the boiling temperature detected by the boiling temperature sensor becomes a predetermined target boiling temperature, and the predetermined heating capacity, the target boiling temperature, and the temperature of the heated water Control means for controlling the circulation pump so as to achieve a target rotational speed corresponding to the target flow rate calculated from the above, and a hot water storage temperature sensor for detecting the hot water storage temperature at a predetermined capacity of the hot water storage tank Sa and the time calculating means for calculating a time (estimated time) which is the hot water storage from the start boiling to the position of the predetermined capacity, time required for being hot-water from the start boiling to a position of a predetermined capacity (actual time) changes and time measuring means for measuring, the target rotational speed by correcting the target flow rate if the calculated prediction time and the comparing actual time measured by the time measuring means, the difference is more than a predetermined by the time calculation means And a target flow rate correcting means.

  According to a second aspect of the present invention, the time measuring means measures time excluding the time when boiling is interrupted.

Thus, according to the present invention, even if the piping conditions between the heat pump unit and the hot water storage tank unit are different for each installation site and the circulation resistance of the circulation circuit changes, the boiling operation is performed without greatly deviating from the target flow rate. It is now possible to carry out the heating while maintaining the target heating capacity.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic block diagram of the heat pump hot water storage type water heater of one Embodiment of this invention. The block diagram which shows the functional structure of the same embodiment.

Next, the heat pump type water heater according to the first embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, 1 is a hot water storage tank unit having a hot water storage tank 2 for storing hot water, 3 is a heat pump unit for heating hot water in the hot water storage tank 2, and 4 is heat connected to the lower part of the hot water storage tank 2. A circulation circuit comprising an incoming water pipe 5 and a heat exchange hot water pipe 6 connected to the upper part of the hot water storage tank 2, 7 is a water supply pipe connected to the lower part of the hot water storage tank 2 for supplying water to the hot water storage tank 2, 8 A hot water supply pipe connected to the upper part of the hot water storage tank 2 for supplying hot water stored in the hot water.

  A plurality of hot water storage tanks 9 are provided on the upper and lower sides of the hot water storage tank 2, and a hot water storage temperature sensor 10 detects the temperature of the hot water in the hot water storage tank 2. Is a hot water storage control means for controlling

  The heat pump unit 3 decompresses the refrigerant 11 that has passed through the water heat exchanger 12, the compressor 11 that compresses the refrigerant, the water heat exchanger 12 that exchanges heat between the high-temperature and high-pressure refrigerant and the hot water in the hot water storage tank 2. A heat pump cycle 15 in which an expansion valve 13 as a pressure reducing means and an air heat exchanger 14 as an evaporator for evaporating a low-temperature and low-pressure refrigerant from the expansion valve 13 are connected in an annular shape by a refrigerant pipe; A circulation pump 16 is provided in the middle of the circulation circuit 4 on the water side to circulate hot water in the hot water storage tank 2. This heat pump cycle 15 is filled with a carbon dioxide refrigerant so as to be in a supercritical state on the high pressure side. The circulation pump 16 is provided with a rotation speed sensor 17.

  Reference numeral 18 denotes a discharge refrigerant temperature sensor that is provided between the compressor 11 and the water heat exchanger 12 and detects the discharge refrigerant temperature Tci. Reference numeral 19 denotes an incoming water temperature sensor that detects the incoming water temperature Twi on the water side of the water heat exchanger 12. , 20 is a boiling temperature sensor for detecting the boiling temperature Two on the water side of the water heat exchanger 15.

  Reference numeral 21 denotes a heating control means for receiving the output of each sensor in the heat pump unit 3 and controlling the operation of each device. The heating control means 21 is communicably connected to the hot water storage control means 10, and in cooperation with the hot water storage control means 10, a heat pump hot water heater. The control apparatus which controls this is comprised.

  The hot water storage control means 10 includes a target boiling temperature determining means 22 for determining the target boiling temperature Tt from the past usage amount of hot water in the hot water storage tank 2, the target boiling temperature Tt and the temperature of the heated water. The target flow rate calculation means 23 for calculating the target flow rate Ft of the heated water flowing through the water heat exchanger 12 from Tw and the predetermined heating capacity W of the heat pump unit 3, and the circulation pump from the relationship between the flow rate stored in advance and the rotational speed Target rotational speed determining means 24 for determining a target rotational speed Nt of 16 and a target time (predicted time te) during which hot water at the target boiling temperature Tt is stored from the start of boiling to a predetermined capacity in the hot water storage tank 2 Time calculating means 25 that calculates based on the flow rate Ft, and the time (actual result) from the start of boiling to the time when hot water at the target boiling temperature Tt is stored up to a predetermined capacity in the hot water storage tank 2 And a target flow rate correction unit 27 that corrects the target flow rate Ft using the predicted time te calculated by the time calculation unit 25 and the actual time tr measured by the time measurement unit 26. Is provided.

  This hot water storage control means 10 has a target rotation temperature corrected by the target boiling temperature Tt determined by the boiling temperature determination means 22, the target rotation speed Nt determined by the target rotation speed determination means 24, or the target flow rate correction means 27. The number Nt is transmitted to the heating control means 21.

  The heating control means 21 determines a target value of the discharge refrigerant temperature Tci based on the target boiling temperature Tt received from the hot water storage control means 10, and the discharge refrigerant temperature Tci detected by the discharge temperature sensor 18 after the start of boiling is the target value. , The opening of the expansion valve 13 is adjusted, the driving frequency of the compressor 11 is adjusted so that the boiling temperature Two detected by the boiling temperature sensor 20 matches the target boiling temperature Tt, and The drive frequency of the circulation pump 16 is adjusted so that the detected rotation speed N of the circulation pump 16 matches the target rotation speed Nt.

Next, the operation of this embodiment will be described.
When hot water is supplied, when a user opens a faucet (not shown), city water flows from the water supply pipe 7 at the bottom of the hot water tank 2 and is boiled from the upper part of the hot water tank 2 and stored in the midnight hours. The hot water that is present is supplied to the hot water supply pipe 8.

  In the midnight time zone, the hot water storage control means 10 instructs the heating control means 21 to start a boiling operation so as to start the boiling operation so that the hot water in the hot water storage tank 2 reaches a predetermined target boiling temperature Tt. Here, the predetermined target boiling temperature Tt is determined by the target boiling temperature determining means 22 so as to ensure the predicted amount of the hot water supply amount on the next day from the actual hot water supply results such as the maximum value and average value of the past hot water supply amount. Therefore, it is determined in the range of 65 ° C to 90 ° C.

  When the target boiling temperature Tt is determined, the hot water storage control means 10 sets the temperature detected by the hot water storage temperature sensor 9d at the lowermost of the hot water storage temperature sensors 9 as the temperature Tw of the heated water, and the target flow rate calculation means 22 Necessary for boiling up the water to be heated at the temperature Tw to the target boiling temperature Tt with the predetermined heating capacity W from the target boiling temperature Tt, the temperature Tw of the water to be heated and the predetermined heating capacity W of the heat pump unit 3. The target flow rate Ft is obtained by the following equation (1) stored in advance.

Ft = W / (Tt−Tw) (1)
(The unit conversion and specific heat constants are omitted in the formula)

  Then, the target rotational speed determination means 24 determines the target rotational speed Nt of the circulation pump 16 from the relationship between the flow rate and the rotational speed stored in advance based on the target flow rate Ft calculated by the target flow rate calculation means 23.

  The heating control means 21 determines the target value of the discharge refrigerant temperature Tci based on the target boiling temperature Tt received from the hot water storage control means 10, and the discharge refrigerant temperature Tci detected by the discharge temperature sensor 18 after the start of boiling reaches the target value. The opening of the expansion valve 13 is adjusted so as to match, the drive frequency of the compressor 11 is adjusted so that the boiling temperature Two detected by the boiling temperature sensor 20 matches the target boiling temperature Tt, and the circulation The drive frequency of the circulation pump 16 is adjusted so that the detected rotational speed N of the pump 16 matches the target rotational speed Nt, and the low-temperature heated water taken out from the lower part of the hot water storage tank 2 is heated to the target boiling temperature Tt. Then, it is returned to the upper part of the hot water storage tank 2 so as to be stacked, and the boiling operation is performed.

  At this time, the time calculating means 25 is the time required for the amount of hot water that is boiled by the heat pump unit 3 and stored in a stacked form from the upper part of the hot water storage tank 2 to be stored to a predetermined capacity position of the hot water storage tank 2 ( Prediction time te) is calculated from the target flow rate Ft. Here, the predetermined capacity of the hot water storage tank 2 is a capacity from the upper part of the hot water storage tank 2 to any one predetermined position of the hot water storage temperature sensors 9a to 9d. For example, in this embodiment, the hot water storage temperature sensor 9b. Is provided at the position of the capacity V from the top of the hot water storage tank 2, V becomes a predetermined capacity, and the predicted time te is obtained from the following equation (2).

te = V / Ft (2)

  When the boiling is started, the time measuring means 26 stores the hot water, which is heated by the heat pump unit 3 and stored in a layered form from the upper part of the hot water storage tank 2, up to a predetermined capacity of the hot water storage tank 2. Measure time (actual time tr) required for. Here, time counting is started at the start of boiling, the time counting is stopped when the temperature of the hot water storage temperature sensor 9b is lower than the target boiling temperature Tt by a predetermined temperature, and the count time from the start of boiling is a record. Time tr is assumed.

  It should be noted that the count stop is set to a temperature lower than the target boiling temperature Tt by a predetermined temperature, and the temperature is lowered due to natural heat dissipation of the heated hot water flowing into the upper portion of the hot water storage tank 2 and mixing with the low temperature hot water existing in the hot water storage tank 2. Even if there is, it is possible to detect that the predetermined capacity has been boiled.

  In addition, when the defrosting operation of the air heat exchanger 14 is started during the boiling, the time measuring means 25 interrupts the time counting during the defrosting operation so that the boiling of a predetermined capacity is performed. The time actually taken up is measured.

  Then, the target flow rate correction unit 27 compares the predicted time te calculated by the time calculation unit 25 with the actual time tr measured by the time measurement unit 26. The correction coefficient K for correcting the calculated target flow rate Ft is calculated, and the target flow rate calculation means 23 multiplies the target flow rate Ft by the correction coefficient K, and here, the target flow rate Ft is multiplied by te / tr, thereby achieving the target The deviation between the flow rate Ft and the actual flow rate is corrected, and the corrected target flow rate Ftr is calculated.

  Next, the target rotational speed determination means 24 determines the target rotational speed Nt of the circulation pump 16 from the relationship between the flow rate and the rotational speed stored in advance based on the corrected target flow rate Ftr.

  Then, the heating control means 21 adjusts the drive frequency of the circulation pump 16 so that the detected rotation speed N of the circulation pump 16 matches the target rotation speed Nt corresponding to the corrected target flow rate Ftr.

  At the next boiling time, the target flow rate calculation means 23 calculates the corrected target flow rate Ftr by multiplying the target flow rate Ft by the correction coefficient K, and uses the corrected target flow rate Ftr for the boiling operation. Like to do.

  Thus, even if the flow rate sensor is abolished for cost reduction, even if a difference in piping conditions between the heat pump unit 3 and the hot water storage tank unit 1 occurs, the boiling operation can be performed without greatly deviating from the target flow rate. Thus, the target rated heating capacity can be maintained, and the boiling operation can be completed by the end time of the midnight time zone.

  The time measuring means 26 stops the counting of the actual time tr by detecting the temperature lower than the target boiling temperature Tt by the hot water storage temperature sensor 9 at a predetermined capacity position. For example, the count of the actual time tr may be stopped by detecting a constant temperature (for example, 50 ° C.) that can be regarded as hot water boiled by the heat pump unit 3 with the hot water storage temperature sensor 9.

DESCRIPTION OF SYMBOLS 1 Hot water storage tank unit 2 Hot water storage tank 3 Heat pump unit 4 Circulation circuit 9 Hot water storage temperature sensor 11 Compressor 12 Water heat exchanger 13 Expansion valve (pressure reduction means)
14 Air heat exchanger (evaporator)
15 Heat pump cycle 16 Circulation pump 20 Boiling temperature sensor 21 Heating control means (control means)
25 Time calculation means 26 Time measurement means 27 Target flow rate correction means

Claims (2)

A hot water storage tank unit containing a hot water storage tank for storing hot water, a heat pump unit having a heat pump cycle in which a compressor, a water heat exchanger, a decompression means and an evaporator are connected in an annular shape, the hot water storage tank and the water heat A circulation circuit that connects the exchanger with a circulation pump so that water can circulate, a boiling temperature sensor that detects an outlet hot water temperature of the water heat exchanger, and a boiling temperature that is detected by the boiling temperature sensor are predetermined targets. The rotation speed of the compressor is controlled so that the boiling temperature is reached, so that the target rotation speed corresponds to the target flow rate calculated from the predetermined heating capacity, the target boiling temperature, and the temperature of the water to be heated. Control means for controlling the circulation pump, a hot water storage temperature sensor for detecting a hot water storage temperature at a predetermined capacity position of the hot water storage tank, and hot water storage from the start of boiling to a predetermined capacity position. Time (predicted time) and time calculation means for calculating, and time measuring means for measuring a time required for being hot-water from the start boiling to the position of the predetermined capacity (actual times), the prediction calculated by the time calculation means comparing the actual time measured in hours and the time measuring means, heat pump, characterized in that the difference is a target flow rate correction means for changing the target rotational speed by correcting the target flow rate if more than a certain Type water heater.   The heat pump type hot water heater according to claim 1, wherein the time measuring means measures time except for the time when boiling is interrupted.

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