JP2011089707A - Hot water storage type water heater, and control method of hot water storage type water heater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an efficient and compact device miniaturizing a hot water supply tank size in regard to a hot water storage type water heater using heat of air and the sun as a heat source. <P>SOLUTION: The hot water storage type water heater has a heat pump cycle carrying out heat exchange with a brine transferring heat of air or the sun. First hot water storage operation of carrying out boiling by an air heat source is carried out in the night, second hot water storage operation of carrying out boiling using solar heat as a heat source is carried out in the day, and a boiling temperature of the second hot water storage operation is set higher than a boiling temperature of the first hot water storage operation. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a hot water storage type hot water supply apparatus and a control method therefor, and particularly relates to boiling in the case where hot water is supplied by driving a heat pump using solar heat as a heat source.

  As a conventional hot water storage type hot water supply device, a hot water tank circulation circuit for circulating water from a hot water tank, a heat pump circuit comprising a compressor and an expansion valve, a solar heat circulation circuit for collecting solar heat and circulating a refrigerant, and collecting solar heat Heat exchanger exchanges heat to heat tank circulating water, heat pump circuit refrigerant exchanges heat to heat tank circulation water, heat pump circuit refrigerant and solar heat circulation circuit Hot water storage type water heater equipped with a third heat exchanger for exchanging heat with the refrigerant, which heats 40% to 70% of the required amount of water in the heat pump circuit during the night time, and the remaining amount of hot water during the day A hot water storage type hot water supply apparatus that heats the minutes by a solar heat circulation circuit and a heat pump circuit is described (for example, Patent Document 1).

  Further, the solar cell panel, a heat pump cycle, a hot water circuit for heating water by a heat pump cycle radiator, a hot water supply tank for storing the heated water, and a heat storage means for exchanging heat with the evaporator of the heat pump cycle are provided. In the solar power generation system, hot water boiled using a heat pump cycle is stored in a hot water tank in the midnight hours and the heat storage means is cooled. Describes a hot water storage type hot water supply apparatus that cools a solar cell panel using a cooled heat storage material (for example, Patent Document 2).

JP 2007-170690 A (0056 column). Japanese Patent Laying-Open No. 2006-183933 (columns 0036 to 0047, FIGS. 1 and 6).

  However, in the hot water storage type hot water supply apparatus of Patent Document 1, since the hot water heated at night is adjusted by the amount of hot water, there is a problem that the operation efficiency is low.

  Moreover, in the hot water storage type hot water supply apparatus of Patent Document 2, hot water is boiled only using the heat pump cycle at night, and there is a problem that the operation efficiency of the heat pump cycle is low.

  The present invention has been made in order to solve the above-described problems. After heating hot water in the first hot water supply operation mode in which hot water is heated using outside air as a heat source, solar water or solar heat is used as a heat source. An object of the present invention is to obtain a hot water storage type hot water supply apparatus having high operating efficiency and its control method by heating the hot water to a temperature higher than the temperature of the hot water boiled in the first hot water supply operation mode in the hot water supply operation mode of No. 2. .

The hot water storage type hot water supply apparatus according to the present invention is:
A water refrigerant heat exchanger that acts as a compressor, an expansion valve, a radiator and heats cold water to hot water, a first evaporator that evaporates the refrigerant using air as a heat source, and a heat medium heated by sunlight or solar heat as a heat source A refrigeration cycle having a second evaporator for heating the refrigerant as
A hot water supply tank for storing hot water heated by the water refrigerant heat exchanger;
A first hot water storage operation mode for operating the first evaporator and the water-refrigerant heat exchanger at night to store the hot water at a first boiling temperature;
The refrigeration cycle is controlled in a second hot water storage operation mode in which the second evaporator and the water-refrigerant heat exchanger are operated during the day to store hot water at a second boiling temperature higher than the first boiling temperature. And a control device for performing the above.

The control method of the hot water storage type hot water supply apparatus according to the present invention is as follows:
A water refrigerant heat exchanger that acts as a compressor, an expansion valve, a radiator and heats cold water to hot water, a first evaporator that evaporates the refrigerant using air as a heat source, and a heat medium heated by sunlight or solar heat as a heat source A refrigeration cycle having a second evaporator for heating the refrigerant as
A hot water supply tank for storing hot water heated by the water refrigerant heat exchanger;
A control method for a hot water storage hot water supply device comprising a control device for controlling the refrigeration cycle,
A first step in which the controller controls the refrigeration cycle to store the hot water at a first boiling temperature at night;
A second step of detecting the temperature of the heat medium;
A third step in which when the temperature detected in the second step is equal to or higher than a predetermined value, the control device stores the hot water at a second boiling temperature higher than the first boiling temperature in the daytime;
It is characterized by having.

  The present invention brings about an effect that the operation efficiency can be improved by further boiling the hot water boiled at night using solar heat higher than the outside air in the daytime as a heat source to raise the boiling temperature of the hot water stepwise.

The block diagram of the hot water storage type hot-water supply apparatus which concerns on Embodiment 1 of this invention. The flowchart which shows the control operation of the hot water storage type hot water supply apparatus which concerns on Embodiment 1 of this invention. The flowchart which showed S1 of control operation of the hot water storage type hot water supply apparatus which concerns on Embodiment 1 of this invention. The another flowchart which showed S1 of control operation of the hot water storage type hot water supply apparatus which concerns on Embodiment 1 of this invention. The block diagram of the hot water storage type hot water supply apparatus which concerns on Embodiment 2 of this invention. The relationship figure of the refrigerant | coolant pressure and enthalpy of the hot water storage type hot-water supply apparatus which concerns on Embodiment 2 of this invention.

Embodiment 1 FIG.
FIG. 1 shows a configuration of a refrigerant circuit, a hot water supply circuit, and a photovoltaic power generation panel cooling circuit of a hot water storage type hot water supply apparatus of the present invention. In FIG. 1, a boiling water circuit 20 a, a refrigerant circuit 20 b constituting a refrigeration cycle, and a panel cooling circuit 20 c for cooling the photovoltaic power generation panel 2 via the panel cooler 3 are mounted in the water heater 1. The boiling circuit 20 a is configured by connecting the hot water supply tank 4, the pump 9 a, the water refrigerant heat exchanger 6, and the hot water supply tank 4 in a ring shape, and water held in the hot water supply tank 4 flows. The refrigerant circuit 20b is configured by connecting the compressor 5, the water refrigerant heat exchanger 6 as a radiator, the expansion valves 7a and 7b, the air heat exchanger 8a as an evaporator, and the brine heat exchanger 8b in a ring shape to form a refrigeration cycle. Carbon dioxide is used as the refrigerant. The panel cooling circuit 20c is configured by connecting the panel cooler 3, the pump 9b, and the brine heat exchanger 8b attached to the back surface of the photovoltaic power generation panel 2 in an annular shape, and brine is used as a heat transfer medium. In this embodiment, the panel cooler 3 collects heat and transfers heat to the brine using the cooling panel 3 as a heat source. However, other configurations may be used, and a solar heat collector capable of collecting solar heat may be used.

  In addition, a control device 13 that performs measurement and control of the water heater 1 is mounted in the water heater 1. The compressor 5 is a type in which the rotation speed is controlled by an inverter and the capacity is controlled. The water-refrigerant heat exchanger 6 is a plate-type or double-pipe heat exchanger, and heat exchange is performed between the refrigerant flowing in and the water flowing through the boiling circuit 20a. The expansion valves 7a and 7b are electronic expansion valves whose opening degrees are variable, the air heat exchanger 8a is connected to the water refrigerant heat exchanger 6 via the expansion valve 7a, and the brine heat exchanger 8b is connected to the water refrigerant heat exchanger 6 via the expansion valve 7b. It is connected. The air heat exchanger 8a performs heat exchange between the outside air blown by the fan and the refrigerant. The brine heat exchanger 8b is a plate-type or double-tube type heat exchanger, and heat exchange is performed between the refrigerant flowing in and the brine flowing through the panel cooling circuit 20c.

The hot water supply tank 4 stores hot water while forming temperature stratification, and hot water is stored in the upper part and low temperature water is stored in the lower part. The pumps 9a and 9b are of a type in which the number of revolutions is controlled by an inverter and the capacity is controlled. The pump 9a circulates water in the boiling circuit 20a, and the pump 9b circulates brine flowing in the panel cooling circuit 20c. The hot water supply tank 4 is connected to a hot water outlet end 21a and a water supply end 21b. When the hot water is discharged from the hot water outlet end 21a based on the demand on the load side, the hot water from the hot water supply tank 4 and the city water supplied from the hot water supply end 21b are mixed by the three-way valve 10 and become the temperature required by the load side. Is done. The amount of hot water decrease in the hot water supply tank 4 at the time of hot water is supplied to the hot water supply tank 4 from the cold water supply end 21b and stays in the lower part of the hot water supply tank 4.

  A temperature sensor 11 is provided in the water heater 1, and measures the refrigerant temperature, water temperature, and brine temperature at the installation location. The temperature sensor 11a is arranged on the suction side of the compressor 5, and the temperature sensor 11b is arranged on the discharge side of the compressor 5, and measures the refrigerant temperature at the arrangement place. The temperature sensor 11c is installed on the inflow side of the hot water supply tank 4 of the boiling circuit 20a, and the temperature sensor 11j is installed on the downstream side of the pump 9a of the boiling circuit 20a, and measures the temperature of water flowing through the boiling circuit 20a. The temperature sensors 11 d to 11 i are installed on the inner surface of the hot water supply tank 4 and measure the water temperature at the installation position height in the hot water supply tank 4. The temperature sensor 11k measures the hot water temperature at the outlet end 21a, and the temperature sensor 11l measures the inflow temperature of the brine heat exchanger 8b of the brine flowing through the panel cooling circuit 20c. The water heater 1 is provided with a pressure sensor 12, the pressure sensor 12 a is disposed on the discharge side of the compressor 5, and the pressure sensor 12 b is disposed on the suction side of the compressor 5.

  The control device 13 in the water heater 1 is based on the measurement information of each temperature sensor 11 and pressure sensor 12 and the operation content instructed by the user of the device, and the operation method of the compressor 5 and the opening degree of the expansion valves 7a and 7b. The fan air flow rate of the air heat exchanger 8a, the operation method of the pumps 9a and 9b, the opening degree of the three-way valve 10 and the like are controlled. The control device 13 has a timer function for measuring time and time.

  Next, the operation of the hot water storage type hot water supply apparatus will be described. In this apparatus, hot water is stored in the hot water supply tank 4 using the first hot water storage operation in which hot water is stored in the hot water supply tank 4 at night using air as a heat source, and the brine flowing in the panel cooling circuit 20c in the daytime as a heat source. A second hot water storage operation is performed.

  The hot water storage situation of the hot water supply tank 4 in the hot water storage operation will be described. The target value of the boiling temperature in the hot water storage operation is set to 55 ° C. in the first hot water storage operation and 90 ° C. in the second hot water storage operation. In general, in a home where a hot water storage type hot water supply apparatus is applied, the amount of hot water consumption from evening to night when hot water is used for hot water filling, showering, etc. is the largest in the day. For this reason, during the midnight hours, the amount of hot water held in the hot water supply tank 4 is small, and most of it is low temperature water supplied from city water. In the first hot water storage operation, the low-temperature water is operated so that the hot water in the hot water supply tank 4 is replaced with hot water having a substantially boiling temperature.

  The second hot water storage operation is performed in the daytime following the first hot water storage operation. The consumption of hot water from morning to daytime at home is generally small, and a large amount of hot water at 55 ° C. stored in the first hot water storage operation remains in the hot water tank 4. In the second hot water storage operation, the hot water is boiled to 90 ° C. and held in the hot water supply tank 4. The second hot water storage operation is performed during the daytime when power is generated by the photovoltaic power generation panel 2. After the second hot water storage operation, it becomes evening, and the hot water stored in the hot water tank 4 is used to cope with the hot water supply load from evening to night.

  In this apparatus, the temperature of the initial city water, generally about 15 ° C., is finally raised to 90 ° C. in the hot water supply tank 4. Since the first hot water storage operation and the second hot water storage operation are boiled in two stages, the boiling temperature of the first hot water storage operation is raised so that the heating capacity required for one hot water storage operation does not become excessive. It is desirable to set the temperature to an intermediate level between the initial (city water) temperature at the start and the final boiling temperature. For example, when boiling from 15 ° C. to 90 ° C., an intermediate temperature of about 55 ° C. is desirable. As a result, the heating capacity required for one hot water storage operation becomes excessive, and a situation in which the efficiency decreases can be avoided, so that the operating efficiency of the apparatus can be increased. The initial temperature may be detected by using a detected value of the temperature sensor 11i or the temperature sensor 11j, or may be detected by providing another temperature sensor at the water supply end 21b.

  In addition, you may change the boiling temperature of a 1st hot water storage operation | movement at any time according to an operating condition. When the amount of solar radiation is large and the calorific value of the photovoltaic power generation panel 2 increases and the brine temperature becomes higher than the outside air temperature in summer (for example, April to September), the second hot water storage operation is performed. The efficiency increases, and the deviation of the operation efficiency from the first hot water storage operation increases. In such a case, the boiling temperature of the first hot water storage operation is set lower than the intermediate value between the initial temperature of the hot water supply tank 4 and the final boiling temperature. Thereby, since the situation where the efficiency of one hot water storage operation becomes low can be avoided, the operation efficiency of the apparatus can be increased on average.

  Conversely, if the amount of solar radiation is small, such as during winter (for example, from October to March), or in cloudy or rainy weather, the calorific value of the photovoltaic power generation panel 2 is reduced, and the difference between the brine temperature and the outside air temperature is small. The operation efficiency of the second hot water storage operation decreases. In such a case, the boiling temperature in the first hot water storage operation is set higher than the intermediate value between the initial temperature of the hot water tank 4 and the final boiling temperature, and the required hot water supply capacity in the second hot water storage operation. Set less. Thereby, since the situation where the efficiency of one hot water storage operation becomes low can be avoided, the operation efficiency of the apparatus can be increased on average.

  Also, considering the temperature drop due to heat dissipation of hot water stored in the hot water tank 4 from the end of the first hot water storage operation to the start of the second hot water storage operation, the boiling temperature of the first hot water storage operation is set. An intermediate value between the initial (city water) temperature at the start of boiling in the first hot water storage operation and the final boiling temperature, or a value higher than a predetermined value by a predetermined value may be used. The predetermined value may be changed in summer and winter when the outside air temperatures are different, and may be a small value in summer and a large value in winter.

  Note that the brine temperature in the second hot water storage operation depends on the amount of heat generated in the photovoltaic power generation panel 2. When the amount of solar radiation is large, the power generation amount of the solar power generation panel 2 is increased, and accordingly, the heat generation amount of the solar power generation panel 2 is also increased. Therefore, the temperature of the photovoltaic power generation panel 2 also rises, and the temperature of the brine heated by the panel cooler 3 also rises. When the temperature increase width of the photovoltaic power generation panel 2 is increased, the power generation efficiency is decreased. Therefore, it is necessary to suppress the temperature increase to an appropriate value. Therefore, an operation for decreasing the brine temperature is performed. When the brine temperature decreases, the temperature difference between the brine in the panel cooler 3 and the photovoltaic power generation panel 2 increases, and the heat exchange amount also increases. As the heat exchange amount in the panel cooler 3 is increased, the heat exchange amount on the boiling circuit 20a side is also increased, and the brine temperature is reduced.

  Therefore, when the temperature of the photovoltaic power generation panel 2 rises and it is necessary to suppress the rise, the high pressure target of the refrigeration cycle that is the capacity control target of the compressor 5 is increased so that the heat exchange amount in the refrigeration cycle increases. While changing the value higher, the discharge temperature of the refrigeration cycle which is the opening control target of the expansion valve 7b is also changed higher. Thereby, the refrigerant temperature in the water refrigerant heat exchanger 6 increases, and the temperature difference with water increases, so the amount of heat exchange in the water refrigerant heat exchanger 6 increases. As the amount of heat exchange in the water-refrigerant heat exchanger 6 increases, the amount of heat exchange in the brine heat exchanger 8b also increases, so that the brine is further cooled in the brine heat exchanger 8b. Thereby, the brine temperature which flows into the panel cooler 3 falls, cooling of the photovoltaic power generation panel 2 is accelerated | stimulated, and a temperature rise is also suppressed. By this control, it is possible to avoid a decrease in power generation efficiency of the photovoltaic power generation panel 2 and obtain a larger amount of power generation.

  Moreover, when there is little solar radiation amount, the electric power generation amount of the solar power generation panel 2 falls, and the heat_generation | fever amount in the solar power generation panel 2 also reduces in connection with it. Therefore, the temperature of the photovoltaic power generation panel 2 also decreases, and the temperature of the brine heated by the panel cooler 3 also decreases. When the decrease range of the brine temperature increases, the operating low pressure of the refrigeration cycle also decreases and the efficiency of the refrigeration cycle decreases. Therefore, it is necessary to suppress the decrease in the brine temperature to an appropriate value.

  Therefore, when it is necessary to suppress the decrease in the brine temperature, the high pressure target value of the refrigeration cycle that is the capacity control target of the compressor 5 is changed to be low and the expansion is performed so that the heat exchange amount in the refrigeration cycle is reduced. The discharge temperature of the refrigeration cycle, which is the opening control target of the valve 7b, is also changed to a low value. Thereby, the refrigerant temperature in the water refrigerant heat exchanger 6 is lowered and the temperature difference with water is reduced, so that the heat exchange amount in the water refrigerant heat exchanger 6 is reduced. As the amount of heat exchange in the water-refrigerant heat exchanger 6 decreases, the amount of heat exchange in the brine heat exchanger 8b also decreases, so that brine cooling in the brine heat exchanger 8b is also suppressed. As a result, an excessive decrease in the brine temperature can be avoided and the operating low pressure of the refrigeration cycle is increased, so that the operating efficiency of the refrigeration cycle can be maintained high.

Next, a control method in each hot water storage operation will be described with reference to FIG. FIG. 2 is a flowchart showing the control method of the first embodiment. When the operation starts, first, the control device 13 determines whether to perform the first hot water storage operation or the second hot water storage operation (S1). The determination in S1 will be described with reference to the flowcharts shown in FIGS. With respect to the operation time of each hot water storage operation, in FIG. 3, it is determined whether or not it is a late-night charge time zone in S11. If it is the midnight fee time zone, the process proceeds to S2, and if it is not the midnight fee time zone, the process proceeds to S12a. As described above, the first hot water storage operation is performed in the midnight time zone. Generally, the midnight power rate is set, and is performed during a time zone in which the electricity rate is low, for example, from 23:00 to 7:00 the next morning. Next, in S12a, it is determined whether or not it is a predetermined daytime period. If it is the daytime predetermined time zone, the process proceeds to S6. The hot water storage operation No. 2 is defined in advance as a time after noon where the amount of solar radiation is large, for example, between 9:00 and 15:00.
Although the second hot water storage operation is performed in the daytime, it is also performed for cooling the solar power generation panel 2, and therefore, the case where the operation is performed based on the necessity of cooling of the solar power generation panel 2 is described with reference to FIG. explain. In the same manner as in FIG. 3, it is determined in S11 whether or not it is a late night charge time zone. Next, in S12b, when it is a predetermined daytime period, the process proceeds to S13. In S13, when the predetermined time of S12b, for example, 7 o'clock in the morning, is reached, only the brine pump 9b in the water heater 1 is driven, and the process proceeds to S14. In S14, the temperature of the brine is detected by the temperature sensor 11l, and when the brine temperature reaches a predetermined temperature or higher, for example, 30 ° C. or higher, the process proceeds to S6 and the second hot water storage operation is started. Generally, the power generation efficiency of the photovoltaic power generation panel 2 decreases as the brine temperature increases. However, since the suction temperature of the refrigerant sucked into the compressor 5 increases, the operation efficiency of the compressor 5 increases. Therefore, in S14, the predetermined temperature may be determined in advance based on the power generation efficiency of the solar power generation panel 2 to be maintained and stored in the control device 13, or the power generation efficiency of the solar power generation panel 2 and the operation efficiency of the compressor 5 may be stored. Alternatively, it may be determined in advance based on the optimum value and stored in the control device 13. Further, if the predetermined temperature is set to be equal to or higher than the critical temperature of carbon dioxide, the refrigerant sucked into the compressor 5 becomes a high-pressure supercritical state, so that the pressure is increased from the low-pressure gas phase state to the high-pressure supercritical state. It is possible to eliminate the load on the compressor 5 minutes. When the brine temperature is not equal to or higher than the predetermined temperature in S14, the process returns to S13, and the pump 9b is controlled to reduce the flow rate of the brine. As described above, when the first hot water storage operation is performed, the process proceeds to S2, and when the second hot water storage operation is performed, the process proceeds to S6.

  Next, the first hot water storage operation from S2 to S5 will be described. When shifting from S1 to S2, a target value of the boiling temperature in the first hot water storage operation is set (S2). In the present embodiment, the target value of the boiling temperature is set to 55 ° C. as described above.

  Next, each actuator is driven based on the target value of the boiling temperature (S3), the water circulating from the hot water supply tank 4 is heated to a high temperature by the water / refrigerant heat exchanger 6, and the air is heated by the air heat exchanger 8a. Exchange is performed (S4).

  S3 and S4 will be described in detail. In the first hot water storage operation, the compressor 5 and the pump 9a are driven, and the low-temperature water in the hot water supply tank 4 conveyed by the pump 9a is converted into a water / refrigerant heat exchanger of the refrigerant circuit 20b. Heat at 6. The fan of the air heat exchanger 8a is driven to exchange heat with the outside air. The pump 9b is stopped and the expansion valve 7b is also closed, so that the refrigerant and the brine of the panel cooling circuit 20c are not exchanged in heat.

  In the refrigerant circuit 20b, the high-temperature and high-pressure gas refrigerant boosted by the compressor 5 flows into the water-refrigerant heat exchanger 6 and is cooled by heat radiation while heating the low-temperature water flowing into the water-refrigerant heat exchanger 6, Becomes a refrigerant. Thereafter, the refrigerant is depressurized by the expansion valve 7a to become a low-pressure two-phase refrigerant, absorbs heat from the outside air by the air heat exchanger 8a, evaporates, becomes a low-pressure low-temperature gas, and is sucked into the compressor 5.

The low temperature water in the lower part of the hot water supply tank 4 is transported by the pump 9a, heated by the water / refrigerant heat exchanger 6 to become hot hot water, and then returned to the upper part of the hot water supply tank 4. In the hot water supply tank 4, hot hot water stays in the upper part and low temperature water stays in the lower part to form a temperature stratification, and a temperature boundary layer is formed between the hot water and the low temperature water. The proportion of water decreases, the proportion of hot water increases, and the temperature boundary layer moves to the lower part of the hot water supply tank 4.

  The boiling temperature is detected by the temperature sensor 11c, and the operation capacity of the pump 9a is controlled so that this temperature becomes the target temperature. For example, if the boiling temperature is higher than the target value, the operation capacity of the pump 9a is increased, and if it is lower than the target value, the operation capacity of the pump 9b is decreased.

  In the refrigerant circuit 20b, the capacity of the compressor 5 and the opening degree of the expansion valve 7 are controlled according to the boiling temperature set value. In the capacity control of the compressor 5, the high pressure of the refrigeration cycle is controlled to be a target value set in accordance with the boiling temperature set value. For example, when the target value of the boiling temperature is 55 ° C., 9 .5 MPa is set. When the high pressure of the refrigeration cycle measured by the pressure sensor 12b is lower than the target value, the operating capacity of the compressor 5 is controlled to be high, and when the high pressure of the refrigeration cycle measured by the pressure sensor 12b is higher than the target value. The operating capacity of the compressor 5 is controlled to be low. The opening degree control of the expansion valve 7a is controlled so that the discharge temperature of the refrigeration cycle becomes a target value set according to the boiling temperature setting value. For example, when the target value of the boiling temperature is 55 ° C. Set to 70 ° C. When the discharge temperature of the refrigeration cycle measured by the temperature sensor 11b is lower than the target value, the opening degree of the expansion valve 7a is controlled to be small, and the discharge temperature of the refrigeration cycle measured by the temperature sensor 11b is higher than the target value. In this case, the opening degree of the expansion valve 7a is largely controlled.

  Next, the control device 13 determines whether or not hot water at the boiling temperature target value has accumulated in the hot water supply tank 4 (S5). If the boiling temperature target value has not been reached, the process returns to S3. If it is determined that the boiling temperature target value has been reached, the process returns to S1 and then proceeds to the second hot water storage operation in S6. In the determination of S5, based on the temperature sensors 11d to 11i installed in the hot water tank 4, the hot water stagnation state is grasped, and the temperature detected by the temperature sensor 11i provided at the lowermost part of the hot water tank 4 and the boiling are detected. When the temperature difference from the temperature target value is within a predetermined value, for example, within 10 ° C., it is determined that hot water at the boiling temperature target value has accumulated in the hot water supply tank 4. In this case, the operation of the compressor 5, the pump 9a, etc. is stopped, and the first hot water storage operation is terminated.

  Next, the second hot water storage operation from S6 to S9 will be described. When shifting from S1 to S6, a target value of the boiling temperature in the second hot water storage operation is set (S6). In the present embodiment, the target value of the boiling temperature is set to 90 ° C. as described above.

  Next, each actuator is driven based on the target value of the boiling temperature (S7), the water circulating from the hot water supply tank 4 is heated to a high temperature by the water / refrigerant heat exchanger 6, and the water is heated by the brine heat exchanger 8b. Exchange is performed (S8).

  S7 and S8 will be described in detail. In the second hot water storage operation, the compressor 5 and the pump 9a are driven, and the low-temperature water in the hot water supply tank 4 conveyed by the pump 9a is transferred to the water / refrigerant heat exchanger of the refrigerant circuit 20b. Heat at 6. In addition, the pump 9b is operated and heat is exchanged between the brine flowing through the panel cooling circuit 20c and the refrigerant. On the other hand, the fan of the air heat exchanger 8a is stopped, the expansion valve 7a is also closed, and the refrigerant and the outside air are not exchanged in heat.

  In the refrigerant circuit 20b, the high-temperature and high-pressure gas refrigerant boosted by the compressor 5 flows into the water-refrigerant heat exchanger 6 and is cooled by heat radiation while heating the low-temperature water flowing into the water-refrigerant heat exchanger 6, Becomes a refrigerant. Thereafter, the refrigerant is depressurized by the expansion valve 7b to become a low-pressure refrigerant, and the brine heat exchanger 8b absorbs heat from the brine flowing through the panel cooling circuit 20c, is heated, heated, and then sucked into the compressor 5. Since the brine temperature is generally higher than the outside air temperature and is 40 to 60 ° C. and thus higher than the critical temperature of the carbon dioxide refrigerant, 30 ° C., the low pressure side of the refrigeration cycle is generally driven in a supercritical state. Therefore, as in the first hot water storage operation, a two-phase region is generated on the low pressure side and the refrigerant evaporates, but the temperature rises sequentially as it is heated.

  The low temperature water in the lower part of the hot water supply tank 4 is transported by the pump 9a, heated by the water / refrigerant heat exchanger 6 to become hot hot water, and then returned to the upper part of the hot water supply tank 4. Further, the brine flowing through the panel cooling circuit 20c is conveyed by the pump 9b and flows into the panel cooler 3 to suppress the temperature rise of the photovoltaic power generation panel 2 that operates during the daytime and receives and generates power, and inside the panel cooler 3, While the solar power generation panel 2 is cooled, the temperature of itself increases. The brine that has reached a high temperature flows out of the panel cooler 3 and then flows into the hot water heater 1 and passes through the pump 9b and then flows into the brine heat exchanger 8b. Here, the brine cools itself while giving heat to the refrigerant, becomes a low temperature, and flows out of the water heater 1. Since the solar power generation panel 2 is heated by receiving sunlight in an outside air atmosphere, it generally has a higher temperature than the outside air. Since the brine temperature in the panel cooler 3 is also heated by the photovoltaic power generation panel 2, the brine temperature is higher than the outside air, and is about 40 to 60 ° C.

  In the second hot water storage operation, the hot water flows from the hot water supply tank 4 from the photovoltaic power generation panel 2 through the panel cooler 3, the brine heat exchanger 8b, and the water / refrigerant heat exchanger 6 using sunlight and solar heat as heat sources. It will be the driving that is conveyed to. When the heat dissipation before and after each heat exchange is small, the heat balance in the refrigeration cycle is maintained, so the heat exchange amount in the panel cooler 3 and the heat amount for the power required for refrigerant compression in the compressor 5 are added. The amount of heat is transferred to the hot water flowing from the hot water tank 4.

  The boiling temperature is detected by the temperature sensor 11c, and the operation capacity of the pump 9a is controlled so that this temperature becomes the target temperature. The control method of the pump 9a is the same as in the first hot water storage operation.

  The target value of the high pressure of the refrigeration cycle in the refrigerant circuit 20b is raised as the boiling temperature rises and set to 14 MPa. Similarly, the target value of the discharge temperature of the refrigeration cycle is also raised and set to 100 ° C. as the boiling temperature rises. Then, the operation capacity of the compressor 5 and the opening degree of the expansion valve 7b are controlled so as to realize this target value, and the control method is performed in the same manner as in the first hot water storage operation.

  Operation control of the panel cooling circuit 20c is performed by the pump 9b, and the brine temperature at the outlet of the panel cooler 3 detected by the temperature sensor 11l is controlled to be a predetermined value. For example, the control target value of the brine temperature is set to 60 ° C. Is set. When the brine temperature measured by the temperature sensor 11l is higher than the target value, the operating capacity of the pump 9b is increased. When the brine temperature measured by the temperature sensor 11l is lower than the target value, the operating capacity of the pump 9b is increased. Decrease.

  In the second hot water storage operation, as in the first hot water storage operation, the control device 13 determines whether hot water at the boiling temperature target value has accumulated in the hot water supply tank 4 (S9). If the boiling temperature target value has not been reached, the process returns to S7, and if it is determined that the boiling temperature target value has been reached, the hot water storage operation is terminated. In the determination of S9, when the temperature difference between the temperature detected by the temperature sensor 11i provided at the lowermost part of the hot water tank 4 and the boiling temperature target value is within a predetermined value, for example, within 10 ° C., the boiling temperature It is determined that the target value of hot water has accumulated in the hot water supply tank 4, the operation of the compressor 5, the pumps 9a, 9b, etc. is stopped, and the second hot water storage operation is terminated.

  With the above control, the hot water temperature stored in the hot water supply tank 4 through the first hot water storage operation and the second hot water storage operation can be set high. When the hot water is discharged, as described above, the hot water discharged from the hot water supply tank 4 and the city water are mixed by the three-way valve 10 and discharged at the temperature required by the load. At this time, if the hot water temperature in the hot water supply tank 4 is high, the amount of city water mixed when realizing the load side required temperature increases, so that a larger amount of hot water can be supplied. Therefore, when the amount of hot water supplied at the load-side required temperature is constant, when the hot water temperature in the hot water supply tank 4 is high, the amount of hot water that must be held in the hot water supply tank 4 is smaller than when the hot water temperature in the hot water supply tank 4 is low. Can be less. Therefore, the volume of the hot water supply tank 4 can be reduced with respect to a predetermined hot water supply load, and the hot water heater 1 itself can be configured compactly.

  In the first hot water storage operation, the heat source of the refrigeration cycle is outside air, and in the second hot water storage operation, the heat source is brine. In general, in the refrigeration cycle, the efficiency decreases as the temperature difference between the high pressure side and the low pressure side increases. Even in the first hot water storage operation, it is possible to drive the refrigeration cycle by setting the same high temperature as the second hot water storage operation as the boiling temperature, but in this case, the temperature difference between the high and low pressures of the refrigeration cycle is widened. However, the operating efficiency is reduced. Therefore, in the second hot water storage operation, a brine temperature that is higher than the outside air is used as a heat source. Thereby, the temperature difference between the high and low pressures of the refrigeration cycle can be reduced, and even when the hot water temperature stored in the hot water supply tank 4 is operated high, the efficiency of the refrigeration cycle can be increased and the operating efficiency of the apparatus can be increased.

  In the conventional hot water storage type hot water supply apparatus, there are cases where the hot water storage operation is performed at night and in the daytime. However, the boiling temperature of each hot water storage operation is generally the same, and a predetermined amount in the hot water tank 4 is maintained during the hot water storage operation at night. In the daytime hot water storage operation, the operation of boiling the remaining low temperature water in the hot water supply tank 4 is performed. In such an operation, when trying to obtain the effect of making the hot water tank 4 similar to this embodiment compact, it is necessary to set the boiling temperature as high as about 90 ° C. In the operation used for the heat source, the temperature difference between the high pressure side and the low pressure side in the refrigeration cycle is widened, and the operation efficiency is remarkably lowered. For example, compared with the case where the boiling temperature in the night operation is 55 ° C., about 40%. Efficiency is reduced. Even if the refrigeration cycle is driven using solar heat as a heat source in the daytime and high efficiency is obtained, the efficiency of operation at night is greatly reduced, and the efficiency of the apparatus is reduced. In the present embodiment, as described above, the boiling temperature is set in two stages, and the temperature difference between the high and low pressures of the refrigeration cycle in each of the first and second hot water storage operations is reduced. Therefore, it is possible to avoid a significant decrease in efficiency and to obtain a highly efficient device.

  Further, in the conventional hot water storage type hot water supply apparatus, only the first hot water storage operation is generally performed, and the temperature of the hot water stored in the hot water supply tank 4 is operated so as to be approximately 60 ° C. or higher at which Legionella bacteria can be sterilized. It was. In this apparatus, since the inside of the hot water supply tank 4 is heated to a temperature of about 60 ° C. or higher that can sterilize Legionella bacteria, the boiling temperature in the first hot water storage operation is about 60 ° C. You can drive with: Therefore, even in the first hot water storage operation, it is possible to perform an operation with higher efficiency than the conventional hot water storage type hot water supply apparatus.

  In the second hot water storage operation, the power generated by the photovoltaic power generation panel 2 may be used as power for driving the compressor 5 and the pumps 9a and 9b. In this case, since the power consumption required for hot water supply is only the power required for the first hot water storage operation, further high-efficiency operation can be realized.

Embodiment 2. FIG.
In the second embodiment, a configuration in which an internal heat exchanger 14 is provided in the refrigerant circuit for the refrigeration cycle that operates in the second hot water storage operation will be described. The same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted. As shown in FIG. 5, in the internal heat exchanger 14, the high-pressure refrigerant at the inlet of the expansion valve 7b and the low-pressure refrigerant at the outlet of the brine heat exchanger 8b exchange heat. By mounting the internal heat exchanger 14, the refrigerant enthalpy in the brine heat exchanger 8b operates in a lower region than when not mounted. In the second hot water storage operation, since the low pressure of the refrigeration cycle is driven in a supercritical state, the temperature decreases as the refrigerant enthalpy decreases. Therefore, heat exchange is possible even at a lower brine temperature.

  Depending on the operating conditions, the amount of solar radiation may be small and the brine temperature will not rise. If the internal heat exchanger 14 is not installed under this condition, the refrigeration cycle of the refrigeration cycle will be able to exchange heat between the brine and the refrigerant. The operation is performed with the low pressure lowered. For this reason, the difference between the high and low pressures of the refrigeration cycle increases, the required power of the compressor 5 increases, and the operation efficiency of the refrigeration cycle decreases. When the internal heat exchanger 14 is provided as shown in FIG. 5, the refrigerant temperature can be lowered even at the same low pressure, so that it is not necessary to lower the low pressure of the refrigeration cycle even if the brine temperature is lowered. The increase in required power can be avoided, so that the operating efficiency of the refrigeration cycle can be maintained high, and the operating efficiency of the apparatus can be increased.

  Similarly, for the refrigeration cycle operating in the first hot water storage operation, an internal heat exchanger in which the high-pressure refrigerant at the inlet of the expansion valve 7a and the low-pressure refrigerant at the outlet of the air heat exchanger 8a exchange heat. 14 can be provided, but it is better not to provide the internal heat exchanger 14 for the refrigeration cycle operating in the first hot water storage operation. In the refrigeration cycle that operates in the first hot water storage operation, generally, the outside air temperature is equal to or lower than the critical temperature of the carbon dioxide refrigerant. Therefore, the low pressure of the refrigeration cycle is equal to or lower than the critical pressure, and the operation of evaporating in the two-phase part is performed. In this case, even if the operating enthalpy of the refrigerant is lowered by the internal heat exchanger 14, the refrigerant temperature does not change. Therefore, the lowering of the low pressure when the heat source (air) temperature is lowered is avoided, and the operation efficiency is maintained. The effect cannot be obtained.

  The relationship between the refrigerant pressure and the enthalpy in the first hot water storage operation and the second hot water storage operation when the internal heat exchanger 14 is used will be described with reference to FIG. FIG. 6A shows the case of the first hot water storage operation, and FIG. 6B shows the case of the second hot water storage operation. 6 (a) and 6 (b), points A1 and A2 indicate the state of the refrigerant at the inlet of the compressor 5, points B1 and B2 indicate the state of the refrigerant at the outlet of the compressor 5, and point C1 is Point D1 at the outlet of the water refrigerant heat exchanger 6 indicates the state of the refrigerant at the inlet of the air heat exchanger 8a, point C2 is at the outlet of the water refrigerant heat exchanger 6, and point D2 is brine heat. The state of the refrigerant at the inlet of the exchanger 8b is shown. In addition, the arrow in a figure has shown the flow of the refrigerant | coolant.

  When the internal heat exchanger 14 is used, the refrigerant at points A1 and C1 in FIG. 6 (a) is used in the first hot water storage operation, and the refrigerant at points A2 and C2 in FIG. 6 (b) is used in the second hot water storage operation. When the temperatures of the refrigerants at points A1 and C1, and points A2 and C2 are compared, the refrigerants at points C1 and C2 have higher temperatures, so points A1, C1, and A2 The state of the refrigerant at point C2 moves to points a1, c1, a2, and c2, respectively. And after a refrigerant | coolant passes the internal heat exchanger 14, when heat exchange is carried out by the water heat exchanger 6a which is a heat radiator, the air heat exchanger 8a which is an evaporator, or the brine heat exchanger 8b, FIG. The operation is performed in the a1b1c1d1 and a2b2c2d2 cycles shown in a) and (b). That is, point B1 is moved to point b1, point D1 is moved to point d1, point B2 is moved to point b2, and point D2 is moved to point d2.

  Here, comparing the state change of the refrigerant at the outlet of the expansion valve in the first hot water storage operation and the second hot water storage operation, the point d1 shown in FIG. 6A is in the two-phase region of the refrigerant, and the point D1 It is isothermal with other refrigerants. On the other hand, the refrigerant at point d2 shown in FIG. 6B is in a supercritical state, and the temperature is lower than that of the refrigerant at point D2. Therefore, even if the brine temperature falls, it is not necessary to lower the low pressure of the refrigeration cycle, and an increase in required power of the compressor 5 can be avoided.

  Further, the internal heat exchanger 14 has a demerit that the pressure loss due to the increase of the refrigerant path on the suction side of the compressor 5 occurs and the efficiency is lowered. Further, the heat exchange at the suction side of the compressor 5 raises the suction temperature, and the discharge temperature of the compressor 5 also rises. In the first hot water storage operation, the boiling temperature is set lower than that of the conventional hot water supply apparatus. Therefore, when the discharge temperature rises, the temperature rises excessively than the temperature required for boiling. When the temperature rises more than necessary, the power required for the compressor 5 increases accordingly, and the operating efficiency decreases. Therefore, as in this device, when the boiling operation is performed in two stages and one of the low pressure side heat source temperatures (air and brine) of each boiling operation is equal to or higher than the critical temperature of the refrigerant and one is equal to or lower than the critical temperature of the refrigerant. It is desirable that the internal heat exchanger 14 be provided only for the refrigeration cycle in which the heat source temperature is equal to or higher than the critical temperature of the refrigerant because the operation efficiency is most enhanced.

  In the present embodiment, the brine for cooling the photovoltaic power generation panel 2 is used as the heat source for the second hot water storage operation. However, other configurations may be used as long as sunlight and solar heat are used as the heat source. However, the same effect can be obtained. For example, a solar heat collector may be provided, and hot water heated by the heat collector or brine may be used.

  INDUSTRIAL APPLICATION This invention can be utilized for the hot water storage type hot-water supply apparatus which drives a heat pump using solar heat as a heat source, and implements hot water supply.

1 Water heater,
2 solar panels,
3 Panel cooler,
4 Hot water tank
5 compressors,
6 Water refrigerant heat exchanger,
7a, 7b expansion valve,
8a Air heat exchanger,
8b brine heat exchanger,
9a, 9b pump,
10 Three-way valve,
11a, 11b, 11c, 11d, 11e, 11f, 11g, 11h, 11i, 11j, 11k, 11l temperature sensor,
12a, 12b pressure sensor,
13 control device,
14 Internal heat exchanger,
21a Hot spring end,
21b Water supply end

Claims (10)

A water refrigerant heat exchanger that acts as a compressor, an expansion valve, a radiator and heats cold water to hot water, a first evaporator that evaporates the refrigerant using air as a heat source, and a heat medium heated by sunlight or solar heat as a heat source A refrigeration cycle having a second evaporator for heating the refrigerant as
A hot water supply tank for storing hot water heated by the water refrigerant heat exchanger;
A first hot water storage operation mode for operating the first evaporator and the water-refrigerant heat exchanger at night to store the hot water at a first boiling temperature;
The refrigeration cycle is controlled in a second hot water storage operation mode in which the second evaporator and the water-refrigerant heat exchanger are operated during the day to store hot water at a second boiling temperature higher than the first boiling temperature. A control device to be
A hot water storage type hot water supply apparatus characterized by comprising: In the summer, the first boiling temperature is set lower than the intermediate value between the temperature of the cold water heated by the water refrigerant heat exchanger and the second boiling temperature, and in the winter, the first boiling temperature is set to the water refrigerant heat. The hot water storage type hot water supply apparatus according to claim 1 or 1, wherein the hot water storage apparatus is set to be higher than an intermediate value between the temperature of the cold water heated by the exchanger and the second boiling temperature. 2. The hot water storage type hot water supply apparatus according to claim 1, wherein the first boiling temperature is approximately 60 degrees or less and the second boiling temperature is approximately 60 degrees or more. 4. The first hot water storage operation mode is performed in a predetermined time zone at night when the late-night electricity rate is set, and the second hot water storage operation mode is performed in a predetermined time zone in the daytime of the next day. The hot water storage type hot water supply device according to crab. Heat the heat medium with a collector that uses a solar power generation panel as a heat source,
The hot water storage type hot water supply apparatus according to any one of claims 1 to 4, wherein the second hot water storage operation mode is performed when the heat medium becomes a predetermined temperature or higher. The hot water storage type hot water supply apparatus according to claim 5, wherein in the second hot water storage operation mode, the compressor is driven by electric power generated by the solar power generation panel. The hot water storage type hot water supply apparatus according to any one of claims 1 to 6, wherein the refrigerant is carbon dioxide. An internal heat exchanger for exchanging heat with the refrigerant before exiting the water refrigerant heat exchanger and entering the expansion valve and the refrigerant before exiting the second evaporator and before entering the compressor;
The hot water storage type hot water supply apparatus according to claim 7, comprising: The hot water storage type hot water supply apparatus according to claim 8, wherein the refrigerant before exiting the expansion valve and entering the second evaporator is in a supercritical state. A water refrigerant heat exchanger that acts as a compressor, an expansion valve, a radiator and heats cold water to hot water, a first evaporator that evaporates the refrigerant using air as a heat source, and a heat medium heated by sunlight or solar heat as a heat source A refrigeration cycle having a second evaporator for heating the refrigerant as
A hot water supply tank for storing hot water heated by the water refrigerant heat exchanger;
A control method for a hot water storage hot water supply device comprising a control device for controlling the refrigeration cycle,
A first step in which the controller controls the refrigeration cycle to store the hot water at a first boiling temperature at night;
A second step of detecting the temperature of the heat medium;
A third step in which when the temperature detected in the second step is equal to or higher than a predetermined value, the control device stores the hot water at a second boiling temperature higher than the first boiling temperature in the daytime;
A method for controlling a hot water storage type hot water supply apparatus, comprising:

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