JP3864981B2 - Heat pump water heater - Google Patents

Description

  The present invention relates to a heat pump water heater.

As a conventional heat pump hot water supply apparatus, a hot water supply apparatus as described in Patent Document 1 has been proposed. As shown in FIG. 6, the heat pump hot water supply apparatus in Patent Document 1 includes a refrigerant circulation circuit 7 in which a compressor 2, a radiator 3, a decompression unit 4, and a heat absorber 5 are connected by a refrigerant flow path 1 configured in a closed circuit. A heat exchanger 10 having a water channel 9 for exchanging heat with the refrigerant channel a8 of the radiator 3, a water supply pipe 11 for supplying tap water to the water channel 9, and the water channel 9 and a shower or faucet A hot water supply circuit 13 for connecting the hot water supply terminal 12 such as a temperature sensor 14 provided in the hot water supply circuit 13 for detecting the hot water supply temperature, and an inverter 15 for controlling the rotation speed of the compressor 2. The output frequency of the inverter 15 is converted according to the difference between the detected temperature and the set temperature. That is, in the conventional hot water supply apparatus, the control is performed such that the rotation speed of the compressor 2 is increased when the hot water supply temperature is lower than the set temperature, and the rotation speed is decreased when the hot water supply temperature is high.
JP-A-2-223767

  However, in the configuration of the conventional hot water supply apparatus, the hot water supply load during hot water supply is not constant. In particular, since the flow rate is varied by the user depending on the purpose of hot water supply, the hot water supply load changes greatly. For example, in the case of hot water supply for home use, a large flow rate of 10 to 20 L / min is used when supplying hot water to a shower or bath, but 3 to 5 L / min for washing dishes in the kitchen or hot water supply to the wash surface. Small flow rate. Also, the hot water supply load varies greatly depending on the seasonal change in the temperature of the water supply.

  A hot water supply load that changes greatly due to changes in flow rate and water temperature can be controlled by changing the number of rotations of the compressor according to the difference between the hot water supply temperature and the set temperature as in conventional heat pump hot water supply devices. If the hot water heating capacity is exceeded, hot water having a temperature lower than the target temperature will be produced, which may cause discomfort to the user.

  In addition, since the heat pump hot water supply apparatus as in the conventional example takes time to rise in the pressure and temperature of the entire refrigerant circulation circuit at the start of hot water supply, there is a delay in the rise of the hot water temperature from the water flow path of the heat exchanger. In the conventional configuration at the start of this hot water supply, since the rotation speed of the compressor is only set based on the difference between the hot water supply temperature and the set temperature, it takes time to reach the target hot water temperature for hot water supply with a large flow rate.

  As described above, the conventional heat pump hot water supply apparatus has problems such as being unable to supply hot water at a target temperature when a hot water supply load such as a large flow rate is large, or taking time to reach the target temperature.

  The present invention solves the above-described conventional problems, and an object of the present invention is to provide a heat pump hot water supply apparatus that has good controllability of hot water temperature and has a rapid rise in hot water temperature.

In order to solve the above-described problems, the heat pump water heater of the present invention includes a refrigerant circuit including a compressor, a radiator, a decompression unit, and a heat absorber, and a water flow path that performs heat exchange with the radiator. A heat exchanger, a water supply pipe for supplying tap water to the water flow path, a hot water supply circuit connected so as to pass water from the water flow path to the hot water supply terminal, and a water amount adjusting means for adjusting a water amount of the water flow path, A flow rate detection means for detecting the flow rate of the hot water supply circuit, and when the flow rate detection means determines that the hot water supply is stopped without detecting the amount of water, when a predetermined time has passed since the hot water supply stopped, The heat pump hot water supply device is characterized in that the opening of the water amount adjusting means is reduced to a predetermined opening.
The rise time of the temperature and pressure of the refrigerant circuit at the start of hot water supply becomes longer because the amount of heat taken from the heat exchanger increases as the amount of water flowing through the water flow path increases. Therefore, the rising speed of the hot water temperature from the water flow path also slows down, and it takes a long time to reach the target temperature. However, according to the present invention, the water amount is reduced by the water amount adjusting means at the start of hot water supply. And the temperature rise of the heat exchanger can be accelerated, and the time for the tapping temperature to reach the target temperature can be shortened.

  In addition, a refrigerant circulation circuit including a compressor, a radiator, a decompression unit, and a heat absorber, a heat exchanger having a water channel for exchanging heat with the radiator, and a water supply pipe for supplying tap water to the water channel And a hot water supply circuit connected to pass water from the water flow path to the hot water supply terminal, a water amount adjusting means for adjusting the amount of water in the hot water supply circuit, and a flow rate detecting means for detecting the flow rate of the hot water supply circuit, At the start of hot water supply, the water amount adjusting means is set to an initial opening previously throttled by a predetermined amount, and if the flow rate detecting means detects the amount of water and determines that hot water is being supplied, a predetermined time has elapsed since the start of hot water supply. The heat pump hot water supply device is characterized in that the opening of the water amount adjusting means is fully opened.

  According to the present invention, by decreasing the amount of water until a predetermined time has elapsed since the start of hot water supply, the rising rate of the hot water temperature is accelerated, and the decrease in the amount of water is canceled when the predetermined time is reached. Thereafter, hot water can be supplied at the original hot water flow rate.

  As described above, according to the present invention, it is possible to provide a heat pump hot water supply apparatus that has good responsiveness and stability in hot water supply control and that has a quick rise in hot water temperature.

  The invention according to claim 1 is a refrigerant circulation circuit including a compressor, a radiator, a decompression unit, and a heat absorber, a heat exchanger provided with a water channel for exchanging heat with the radiator, and a water pipe in the water channel. A water supply pipe for supplying water, a hot water supply circuit connected so as to pass water from the water flow path to the hot water supply terminal, a water amount adjusting means for adjusting the amount of water in the water flow path, and a flow rate detection for detecting the flow rate of the hot water supply circuit And when the flow rate detecting means determines that the hot water supply is stopped without detecting the amount of water, when the predetermined amount of time has passed since the hot water supply stopped, the opening of the water amount adjusting means is set to the predetermined opening degree. It is set as the heat pump hot-water supply apparatus characterized by setting it as the restrict | squeezed state.

  The rise time of the temperature and pressure of the refrigerant circuit at the start of hot water supply becomes longer because the amount of heat taken from the heat exchanger increases as the amount of water flowing through the water flow path increases. Therefore, the rising speed of the hot water temperature from the water flow path also slows down, and it takes a long time to reach the target temperature. However, according to the present invention, the water amount is reduced by the water amount adjusting means at the start of hot water supply. And the temperature rise of the heat exchanger can be accelerated and the time for the tapping temperature to reach the target temperature can be shortened.

  The invention according to claim 2 is a refrigerant circulation circuit including a compressor, a radiator, a decompression unit, and a heat absorber, a heat exchanger provided with a water channel for exchanging heat with the radiator, and a water pipe in the water channel. A water supply pipe for supplying water, a hot water supply circuit connected to pass water from the water flow path to the hot water supply terminal, and a water amount adjusting means for adjusting the amount of water in the hot water supply circuit, wherein the flow rate detecting means detects the water amount. If it is determined that the hot water is being supplied, when the predetermined time has elapsed since the hot water supply was started, the opening of the water amount adjusting means is fully opened.

  According to the present invention, by decreasing the amount of water until a predetermined time has elapsed since the start of hot water supply, the rising rate of the hot water temperature is accelerated, and the decrease in the amount of water is canceled when the predetermined time is reached. Thereafter, hot water can be supplied at the original hot water flow rate.

  Embodiments of the present invention will be described below with reference to the drawings. In the conventional example and each example, parts having the same configuration and the same operation are denoted by the same reference numerals, and detailed description thereof is omitted.

Example 1
FIG. 1 is a configuration diagram of a heat pump type hot water supply apparatus in Embodiment 1 of the present invention. In FIG. 1, reference numeral 7 denotes a refrigerant circulation circuit, in which a compressor 2, a radiator 3, a decompression unit 4, and a heat absorber 5 are connected to a closed circuit by a refrigerant flow path 1. The refrigerant circuit 7 uses, for example, carbon dioxide (CO2) as a refrigerant, and uses a supercritical heat pump cycle in which the refrigerant pressure on the high-pressure side is equal to or higher than the critical pressure of the refrigerant. The compressor 2 is driven by a built-in electric motor (not shown), and compresses and sucks the sucked refrigerant to a pressure exceeding the critical pressure. Reference numeral 10 denotes a heat exchanger provided with a water channel 9 for exchanging heat with the refrigerant channel a8 of the radiator 3. A water supply pipe 11 for directly supplying tap water to the water flow path 9 and a hot water supply circuit 13 for passing hot water discharged from the water flow path 9 through a hot water supply terminal 12 including a shower 16 and a faucet 17 are connected. . Reference numeral 18 denotes a water amount adjusting means for adjusting the amount of water in the water flow path 9, which is constituted by an electric throttle valve and provided in the water supply pipe 11.

  Reference numeral 19 denotes a control means, a hot water supply load detection means 20 for obtaining a hot water supply load which is the amount of hot water supply to the hot water supply circuit 13, a heat quantity detection means 21 for detecting the heating amount of the water flow path 9 in the heat exchanger 10, and a compressor. Heating control means 22 for controlling the frequency and the decompression means is provided.

  The control means 19 drives the throttle valve, which is the water amount adjusting means 18, by a predetermined amount in advance so as to reduce the amount of water at the start of hot water supply, and the value of the hot water supply load detection means 20 sets the value of the heat quantity detection means 21. When exceeding, the water amount adjusting means 18 controls the water flow rate of the water flow path 9 to be lowered so that the value of the hot water supply load detecting means 20 matches the value of the heat amount detecting means 21.

  The water supply pipe 11 is provided with a flow rate detection means 23 for detecting the flow rate of the hot water supply circuit 13 and a water temperature detection means 24 for detecting the temperature of the water supply to the heat exchanger 10. The hot water supply circuit 13 is provided with hot water temperature detection means 25 for detecting the temperature of the hot water discharged from the water flow path 9. Reference numeral 26 denotes temperature setting means for setting a target temperature for hot water supply, and the user arbitrarily sets the temperature. Reference numeral 27 denotes an outside air temperature detecting means for detecting the air temperature.

  The heat exchanger 10 is configured so that the flow direction of the refrigerant flow path a8 and the flow direction of the water flow path 9 are opposed to each other, and the flow paths are in close contact with each other so as to facilitate heat transfer. With this configuration, heat transfer between the refrigerant flow path a8 and the water flow path 9 is made uniform, and heat exchange efficiency is improved. In addition, hot water can be discharged.

  The heating control means 22 includes a frequency control means 28 for changing the rotation speed of the compressor 2 so that the deviation between the hot water temperature output from the hot water temperature detection means 25 and the temperature setting means 26 and the target temperature is reduced. Further, the frequency of the compressor 2 is controlled by a known PID (not shown). Further, the heating control means 22 controls the opening degree of the decompression means 4 so that the refrigerant discharge temperature of the compressor 2 is a predetermined temperature and the pressure balance of the refrigerant circulation circuit 7 becomes appropriate.

  FIG. 2 is a control flowchart of the water amount adjusting means 18 at the start of hot water supply in the first embodiment. In FIG. 2, 30 determines whether hot water is being supplied. The determination condition is that hot water is being supplied when the flow rate detection means 23 detects the amount of water. And when it determines with there being no water quantity and being stopped, it progresses to 31. Here, it is determined whether 10 minutes have elapsed since the hot water supply was stopped. If 10 minutes have elapsed, the initial opening 60% of the water amount adjusting means 18 is set at 32. If it is determined at 31 that it is less than 10 minutes, the initial opening of 32 is not set. 10 minutes in 31 is a time for determining whether or not to reduce the amount of water when restarting hot water supply, and is set according to the cooling rate of the refrigerant circulation circuit 7 and the heat exchanger 10, so long as it is easy to cool A short time is set, and if it is difficult to cool, a long time is set.

  If it is determined at 30 that hot water is being supplied, the process proceeds to 34. Here, it is determined whether or not 5 minutes have elapsed since the start of hot water supply. If 5 minutes have elapsed, the opening of the water amount adjusting means 18 is fully opened at 35. Set to%. Even if it is less than 5 minutes at 34, if the hot water temperature Thw exceeds the target temperature Tset-5K at 36, the opening of the water amount adjusting means 18 is set to fully open at 35. And when the conditions of 34 and 36 are not satisfied, the opening degree of the water quantity adjusting means 18 remains the initial opening degree.

  The initial opening 60% at 32 is a level at which the water volume can be reduced without a sense of incongruity to the user, and needs to be set to a value at which the rise of the tapping temperature is quickened.

  According to the present invention, by decreasing the amount of water until the tapping temperature of the water flow path reaches a predetermined value, the rising speed of the tapping temperature is accelerated, and when the predetermined amount is reached, the decrease in the amount of water is released. Hot water can be supplied with the original hot water flow rate.

  FIG. 3 is a control flowchart of the water amount adjusting means 18 during hot water supply in the first embodiment. In FIG. 3, reference numeral 40 denotes a hot water supply load calculation of the hot water supply load detection means 20. Here, the difference between the water temperature Tw (° C.) detected by the water temperature detecting means 24 and the target temperature Tset (° C.) set by the temperature setting means 26 is multiplied by the flow rate W (L / min) detected by the flow rate detecting means 23. Then, this is multiplied by the conversion coefficient (60/860) to obtain the hot water supply load Qhw (kW). Although the calculation accuracy is deteriorated, the hot water supply load may be calculated by using the water temperature as a representative fixed value or the target temperature as a fixed value. According to this, the water temperature detecting means 24 and the temperature setting means 26 become unnecessary, and can be operated even at the time of failure.

  41 shows the setting of the heating amount Qhx (kW) in the heat amount detecting means 21. This reads the heating amount Qhx from the heating amount table 42 from the outside air temperature To (° C.) detected by the outside air temperature detector 27 and the water temperature Tw of the water temperature detector 24. The values in this table 42 are set in advance by experimentally determining the maximum heating amount under the combination conditions of the outside air temperature and the water temperature. This table may be a mathematical expression. Moreover, it is good also as a table | surface of the ternary heating amount of outside temperature, water temperature, and target temperature, the binary data which consists of another two elements out of outside temperature, water temperature, and target temperature may be sufficient. Although the system is worse, a single table with only one element may be used. This reduces the amount of experiment and reduces the memory.

  In the case where the hot water supply load Qhw exceeds the heating amount Qhx, the opening amount reduction setting for reducing the water amount by the water amount adjusting means 18 is performed in 44. On the other hand, if Qhw is smaller than Qhx in 43, the opening degree setting for returning the water amount by the water amount adjusting means 18 is performed in 45. The control here acts to reduce the amount of water so that the hot water supply load matches the heating amount when the hot water supply load exceeds the heating amount. 46 and 47 define an upper limit value for opening reduction, and 48 and 49 define a lower limit value for opening reduction. The lower limit is set to -70%. Even if the amount of water adjustment means 18 advances due to an abnormality or the like, a minimum opening of 30% is ensured so that it is fully closed and hot water supply is not stopped. ing.

  50 sets the opening degree of the water amount adjusting means 18. Here, the final opening setting X is obtained by adding the reduced opening Xd to the opening Xi at the start of hot water supply described in FIG. Then, at 51, the water amount adjusting means 18 is driven to the set opening degree.

  The operation and action of the above configuration will be described. When the faucet 17 is opened, tap water starts to flow from the water supply pipe 11. This is detected by the flow rate detection means 23, a signal is sent to the control means 19, and the compressor 2 is started.

  At this time, since the water amount adjusting means 18 is restricted to the initial opening, the amount of water is suppressed and the hot water is discharged. Therefore, the amount of heat exchange from the heat radiation means 3 to the water flow path 9 of the refrigerant circulation circuit 7 is suppressed, the temperature rise speed of the compressor 2 and the heat exchanger 10 is increased, and the temperature rise speed of the tapping temperature from the water flow path 9 is increased. Becomes faster. When the hot water temperature rises to (target temperature -5K) or higher, the initial opening degree throttled by the water amount adjusting means 18 is released, and the full opening is restored. At this time, since the pressure and temperature of the compressor 2 and the heat exchanger 10 are sufficiently increased, even if the amount of water is restored, the tapping temperature can be reached without decreasing.

  The heating control means 22 controls the frequency of the compressor 2 based on the deviation between the tapping temperature and the target temperature. The high-temperature and high-pressure refrigerant gas discharged from the compressor 2 flows into the radiator 3 and heats the water flowing through the water flow path 9. The heated water is discharged from the hot water supply terminal 12 through the hot water supply circuit 13. On the other hand, the refrigerant cooled by the radiator 3 is decompressed by the decompression means 4 and flows into the heat absorber 5, where it absorbs natural energy such as atmospheric heat and solar heat to evaporate and returns to the compressor 2. Accordingly, the hot water is detected, and the high-temperature and high-pressure refrigerant gas from the compressor 1 immediately flows into the radiator 3 to heat the water, and the hot water can be used from the hot water supply terminal 12 as it is.

  The heating control means 22 during hot water supply calculates the frequency using the known PID control from the deviation between the tapping temperature and the target temperature. That is, feedback control of the tapping temperature is performed. The proportional constant, integral coefficient, and differential coefficient, which are control constants here, need to be set in advance to optimum values for achieving both control response and stability. The feedback control may be PI control, P control, fuzzy or neuro control.

  When hot water supply at a large flow rate such as hot water supply at two or more places occurs during hot water supply and a hot water supply load exceeding the maximum heating amount in the heat exchanger 10 is generated, the control means 19 moves the water amount adjusting means 18 in the throttle direction. Since it is driven and the amount of water is reduced until the hot water supply load substantially coincides with the maximum heating amount, it is possible to maintain the target temperature without drastically lowering the hot water temperature.

  Even when the flow rate changes from a large flow rate to a normal flow rate, if the hot water supply load falls below the maximum heating amount, the throttling at the water amount adjusting means 18 changes from a decrease in the water amount to a return to the water amount and returns to the fully open operation, so that the user does not feel strange. Hot water operation is possible.

  In the first embodiment, the refrigerant circulation circuit is a supercritical refrigerant circulation circuit in which the pressure of the refrigerant is equal to or higher than the critical pressure. However, a refrigerant circulation circuit having a general critical pressure or lower may be used.

(Example 2)
FIG. 4 is a control flowchart of the water amount adjusting means 18 at the time of hot water supply of the heat pump hot water supply apparatus according to Embodiment 2 of the present invention. In addition, the thing of the same structure as the hot water supply apparatus of Example 1 gives the same code | symbol, and abbreviate | omits description. In FIG. 4, the difference from the configuration of the first embodiment is that the water amount adjusting means 18 is controlled by a set value of 55 water amount upper limit. 55, the upper limit WL (L / min) of the water amount is calculated from the maximum heating amount Qhx (kW) obtained by 41, the target temperature Tset (° C.), and the water temperature Tw (° C.). Then, it is determined at 56 whether or not the water amount W (L / min) detected by the flow rate detection means 23 exceeds the upper limit WL of the water amount, and if it exceeds 44, the opening for reducing the water amount by the water amount adjustment means 18 at 44. Make reduction settings. On the other hand, if it does not exceed, an opening increase setting for returning the water amount by the water amount adjusting means 18 is performed at 45.

  As described above, in Example 2, the upper limit of the amount of water is set from the maximum amount of heating, and control is performed so that the detected value of the amount of water does not exceed this upper limit.

(Example 3)
FIG. 5 is a control flowchart of the water amount adjusting means 18 at the time of hot water supply of the heat pump hot water supply apparatus according to Embodiment 3 of the present invention. In addition, the thing of the same structure as the hot water supply apparatus of Example 1 gives the same code | symbol, and abbreviate | omits description. In FIG. 5, the difference from the configuration of the first embodiment is that a second target value that is 5K lower than the target temperature set by the temperature setting means 26 is set, and the hot water temperature is set to the second temperature after 3 minutes from the start of hot water supply. When the heating control means 22 sets the frequency of the compressor 2 to the upper limit, the amount of water is reduced. Specifically, the control is as follows.

  In 60, the frequency of the compressor 2 of the heating control means 22 is set. That is, the frequency F is calculated using a known PID control from the deviation between the hot water temperature Thw and the target temperature Tset.

  61 determines whether 3 minutes have passed since the start of hot water supply. If it is less than 3 minutes, the opening reduction setting for reducing the amount of water is set to 0% at 62, and the decrease in the amount of water is prohibited. If it is determined in 61 that 3 minutes or more have elapsed, the process proceeds to 63.

  If the control frequency F of the compressor 2 is equal to or higher than the upper limit value Fmax and the hot water temperature Thw is lower than the target temperature Tset-3K, the opening amount reduction setting for reducing the water amount by the water amount adjusting means 18 is performed at 44. On the other hand, if the condition of 63 is not satisfied, the opening amount increase setting for returning the water amount by the water amount adjusting means 18 is performed at 45.

  3 minutes from the start of 61 hot water supply sets the time until the capacity and temperature of the entire system rise, and this value varies depending on the system conditions.

  The determination in 63 determines whether or not the maximum heating amount has been reached by the frequency F, and determines whether or not the capacity is insufficient by the tapping temperature Thw. And by these both, it determines with having reached the maximum heating amount and having fallen in capacity. In the third embodiment, the determination accuracy is improved by determining both the frequency F and the tapping temperature Thw. However, even if each determination is made independently, it is possible to determine the lack of ability sufficiently accurately.

  In the above embodiments 1 to 3, a hot water storage device having no hot water storage tank or heat storage material has been described, but if it is configured to supply hot water heated by a heat pump during hot water supply directly to the hot water supply terminal, The same effect can be obtained by having a hot water storage tank in parallel with the heat exchanger, having a hot water storage tank in series with the heat exchanger, and further having a heat storage material in the water circuit or refrigerant circuit. can get.

The block diagram of the heat pump hot-water supply apparatus in Example 1 of this invention Control flow chart of water amount adjusting means at the start of hot water supply in Embodiment 1 of the present invention Control flow chart of water amount adjusting means at the time of hot water supply in Embodiment 1 of the present invention Control flow chart of water amount adjusting means at the time of hot water supply in Embodiment 2 of the present invention Control flow chart of water amount adjusting means during hot water supply in Embodiment 3 of the present invention Configuration diagram of conventional heat pump water heater

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 Compressor 3 Radiator 4 Pressure reduction means 5 Heat absorber 7 Refrigerant circulation circuit 9 Water flow path 10 Heat exchanger 11 Water supply pipe 12 Hot water supply terminal 13 Hot water supply circuit 18 Water quantity adjustment means 20 Hot water supply load detection means 21 Heat quantity detection means 22 Heating control means 23 Flow rate detection means 24 Water temperature detection means 25 Hot water temperature detection means 26 Temperature setting means 27 Outside air temperature detection means

Claims (2)

A refrigerant circulation circuit including a compressor, a radiator, a decompression unit, and a heat absorber; a heat exchanger including a water channel that exchanges heat with the radiator; a water supply pipe that supplies tap water to the water channel; A hot water supply circuit connected so as to pass water from the water flow path to the hot water supply terminal, a water amount adjusting means for adjusting the amount of water in the water flow path, and a flow rate detecting means for detecting a flow rate of the hot water supply circuit. If the detection means does not detect the amount of water and it is determined that the hot water supply is stopped, the opening of the water amount adjustment means is reduced to the predetermined opening when a predetermined time has elapsed since the hot water supply stopped. Heat pump water heater. A refrigerant circulation circuit including a compressor, a radiator, a decompression unit, and a heat absorber; a heat exchanger including a water channel that exchanges heat with the radiator; a water supply pipe that supplies tap water to the water channel; A hot water supply circuit connected to pass water from the water flow path to the hot water supply terminal, a water amount adjusting means for adjusting the amount of water in the hot water supply circuit, and a flow rate detecting means for detecting the flow rate of the hot water supply circuit, Sometimes when the water amount adjusting means is set to an initial opening previously throttled by a predetermined amount, and when the flow rate detecting means detects the amount of water and determines that hot water is being supplied, a predetermined time has elapsed since the start of hot water supply. The heat pump hot water supply apparatus is characterized in that the opening of the water amount adjusting means is fully open.

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