JP2009250461A - Heat pump hot water supply device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat pump hot water supply device capable of detecting scale in a heat exchanger for hot water supply at an early time. <P>SOLUTION: This heat pump hot water supply device comprises: a heat pump cycle; a hot water storage tank 20; a water circuit connected to an upper portion of the hot water storage tank 20 from a lower portion in the hot water storage tank 20 through a heat exchanger 12 for hot water supply; a circulation pump 23 for conveying hot water/water in the water circuit; a flow rate detecting means 20F for detecting a flow rate in the water circuit; a target hot water supply temperature setting means 44 for setting a target hot water supply temperature after heat exchange by the heat exchanger for hot water supply; and a pump output detecting means 23A for detecting the output of the circulation pump 23. The target hot water supply temperature is limited when the flow rate detected by the flow rate detecting means 20F is lowered though the output of the circulation pump 23 detected by the pump output detecting means 23A is same as the output of the circulation pump 23 in the last operation in operation by driving the circulation pump 23. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a heat pump water heater.

  Conventionally, means for detecting flow rate changes, means for detecting pressure changes, means for detecting changes in pump output, and detecting changes in hot water heating capacity in order to quickly detect abnormalities in the water circuit flowing through the hot water heat exchanger. There has been proposed a heat pump hot-water supply device provided with a means for performing the above.

  And the heat pump hot-water supply apparatus provided with the various means which alert | reports abnormality based on the clogging detection of a water circuit by these detection means, the means to stop the operation of a compressor, etc. is proposed (for example, patent document 1). reference).

In Patent Document 1, it is possible to improve reliability by quickly detecting clogging of the water circuit.
JP 2004-116942 A

  However, in general, water for hot water supply such as tap water and groundwater contains hardness components such as calcium and magnesium, and depending on the region, contains very much such hardness components. Therefore, when water containing a relatively large amount of hardness component is heated to a high temperature for a long time with a heat exchanger for hot water supply of a heat pump water heater, the hardness component precipitates as a scale around the vicinity of the outlet portion of the water circuit that becomes the highest temperature. there is a possibility.

  If such a scale adheres to and accumulates on the heat transfer surface of the water circuit of the heat exchanger for hot water supply or the inner circumference of the pipes that make up the water circuit, it becomes a flow resistance of water and pressure loss increases. The load of the water pump is increased, or the heat resistance of the heat transfer surface when heat is exchanged between the refrigerant and the water, and the performance as a heat exchanger is significantly reduced. Furthermore, when the water circuit is completely blocked by the scale, there is a problem that the hot water supply operation by the heat pump hot water supply device becomes impossible.

  This invention solves the said conventional subject, and it aims at providing the heat pump hot water supply apparatus which can detect the scale of the heat exchanger for hot water supply at an early stage.

  In order to solve the above-mentioned conventional problems, a heat pump hot water supply apparatus of the present invention includes a heat pump cycle configured by sequentially connecting a compressor, a hot water heat exchanger, an expansion valve, and an evaporator in an annular manner through a refrigerant pipe, A hot water storage tank for storing liquid for use, a water circuit connected from the lower part of the hot water storage tank to the upper part of the hot water storage tank via the hot water supply heat exchanger, and a circulation for transporting the hot water in the water circuit A pump, flow rate detecting means for detecting a flow rate in the water circuit, target hot water temperature setting means for setting a target hot water temperature after heat exchange in the hot water heat exchanger, and output of the circulation pump A pump output detecting means for detecting the output of the circulating pump, and when the circulating pump is driven to operate, the output of the circulating pump detected by the pump output detecting means is the same as the output of the circulating pump at the previous operation. However, when the flow rate detected by the flow rate detecting means is low, by limiting the target hot water temperature, scale clogging can be found quickly and scale clogging has been found. It is possible to prevent the occurrence of further scale later and to extend the life of the heat exchanger for hot water supply.

  The present invention can provide a heat pump hot water supply apparatus that can detect the scale of a heat exchanger for hot water supply at an early stage.

  A heat pump hot water supply apparatus according to a first aspect of the present invention includes a heat pump cycle configured by sequentially connecting a compressor, a hot water heat exchanger, an expansion valve, and an evaporator in an annular manner through a refrigerant pipe, and a hot water storage tank for storing hot water liquid. A water circuit connected from the lower part of the hot water storage tank to the upper part of the hot water storage tank via the heat exchanger for hot water supply, a circulation pump for conveying hot water in the water circuit, A flow rate detecting means for detecting a flow rate, a target hot water temperature setting means for setting a target hot water temperature after heat exchange in the hot water heat exchanger, and a pump output detecting means for detecting an output of the circulation pump. The output of the circulating pump detected by the pump output detecting means when the circulating pump is driven to operate is the same as the output of the circulating pump at the previous operation. When the flow rate detected by the discharge means is reduced, by limiting the target hot water temperature, it is possible to find scale clogging as soon as possible and to generate further scale after finding scale clogging. It can suppress and can prolong the life of the heat exchanger for hot water supply.

  A heat pump hot water supply apparatus according to a second aspect of the present invention includes a heat pump cycle configured by sequentially connecting a compressor, a hot water heat exchanger, an expansion valve, and an evaporator in an annular manner by a refrigerant pipe, and a hot water storage tank for storing hot water liquid. A water circuit connected from the lower part of the hot water storage tank to the upper part of the hot water storage tank via the heat exchanger for hot water supply, a circulation pump for conveying hot water in the water circuit, Water pressure detection means for detecting water pressure, target hot water temperature setting means for setting a target hot water temperature after heat exchange in the hot water heat exchanger, and pump output detection means for detecting the output of the circulation pump When the circulating pump is driven and operated, the output of the circulating pump detected by the pump output detecting means is the same as the output of the circulating pump during the previous operation. When the water pressure detected by the force detection means is reduced, by limiting the target tapping temperature, scale clogging can be found quickly and further scale clogging occurs after the clogging is found. It is possible to extend the life of the heat exchanger for hot water supply.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, this invention is not limited by this embodiment.

(Embodiment 1)
FIG. 1 is a circuit configuration diagram of the heat pump water heater in the first embodiment of the present invention. First, the heat pump circuit of the heat pump hot water supply apparatus according to this embodiment will be described.

  The heat pump circuit 10 according to the present embodiment preferably uses carbon dioxide as a refrigerant and is operated in a state where the critical pressure is exceeded on the high pressure side. The heat pump circuit 10 is configured by connecting a compressor 11, a hot water supply heat exchanger 12, a main expansion valve 13A, a capillary tube 13B, and an evaporator 14 in this order by piping. The heat pump circuit 10 includes a temperature sensor 10 </ b> A that detects the temperature of the compressor 11, a temperature sensor (discharge refrigerant temperature detection means) 10 </ b> B that detects a refrigerant temperature discharged from the compressor 11, and a refrigerant pressure discharged from the compressor 11. And a temperature sensor 10D for detecting the intake air of the evaporator 14. Here, the temperature sensor 10 </ b> A detects cold start, and the pressure sensor 10 </ b> C detects abnormality of the compressor 11 or the heat pump circuit 10.

Next, the water circuit of the heat pump water heater according to this embodiment will be described. A bottom pipe 21 of the hot water storage tank 20 is connected to a water supply pipe 32 such as a water pipe via a pressure reducing valve 31.
The bottom piping 22 of the hot water storage tank 20 is connected to the inflow side of the water piping 12 </ b> A of the hot water supply heat exchanger 12 through the circulation pump 23. The upper circulation pipe 24 of the hot water storage tank 20 is connected to the outflow side of the water pipe 12A. In this way, a water circuit is formed by sequentially connecting the bottom of the hot water storage tank 20, the circulation pump 23, and the hot water supply heat exchanger 12 with the hot water supply pipe. The hot water storage tank 20 according to the present embodiment is a stacked hot water storage tank, and is configured so that stirring in the tank is prevented and high temperature water is accumulated at the top and low temperature water is accumulated at the bottom.

  On the other hand, the upper hot water supply pipe 33 of the hot water storage tank 20 is connected to the mixing valve 34. Further, a water discharge pipe 35 branched from the bottom pipe 21 of the hot water storage tank 20 is connected to the mixing valve 34. The outlet circuit on the outflow side of the mixing valve 34 is connected to a faucet 36 for hot water supply such as a kitchen or a washroom. This tapping circuit is provided with a flow sensor 30A for detecting the tapping amount and a temperature sensor 30B for detecting the tapping temperature.

The hot water storage tank 20 is provided with a plurality of temperature sensors 20A, 20B, 20C for detecting the amount of hot water in the hot water storage tank 20. In addition, a temperature sensor (incoming water temperature detecting means) 20 </ b> D for detecting the incoming water temperature derived from the bottom pipe 22 of the hot water storage tank 20 is provided in the inflow side pipe of the water pipe 12 </ b> A. In addition, the upper circulation pipe 24 is provided with a temperature sensor 20E that detects a tapping temperature derived from the water pipe 12A. Further, a flow meter (flow rate detecting means) 20F for detecting the flow rate of water derived from the water pipe 12A is provided.
Further, a pressure gauge (water pressure detecting means) 20G for detecting the water pressure derived from the water pipe 12A is provided.

  Hereinafter, the hot water storage operation of the heat pump hot water supply apparatus according to the present embodiment will be described.

  When the time reaches a predetermined time or the temperature sensors 20A, 20B, and 20C in the hot water storage tank 20 detect that the amount of hot water in the hot water storage tank 20 has become less than a predetermined amount, the heat pump circuit 10 is operated to store hot water. Start driving. In the heat pump circuit 10, the refrigerant compressed by the compressor 11 dissipates heat in the hot water supply heat exchanger 12, is depressurized by the main expansion valve 13A and the capillary tube 13B, then absorbs heat in the evaporator 14, and in a gas state. It is sucked into the compressor 11.

  On the other hand, by the operation of the circulation pump 23, the water in the hot water storage tank 20 is guided to the water pipe 12A through the bottom pipe 22, and the hot water heated by the water pipe 12A passes through the upper circulation pipe 24. It is returned to the hot water storage tank 20. The capacity control in the compressor 11 and the opening degree control in the expansion valve 13 are controlled such that the refrigerant discharge refrigerant temperature detected by the temperature sensor 10B maintains a preset temperature.

  Next, target hot water temperature setting control during hot water storage operation of the heat pump hot water supply apparatus according to the present embodiment will be described with reference to FIGS.

  The boiling of hot water in the hot water storage tank 20 is controlled by a plurality of boiling modes, and each of the plurality of boiling modes has a different boiling setting. As long as the same heating mode is selected, the hot water in the hot water storage tank 20 is controlled to be heated at the same setting every night.

  For a predetermined time from the start of the compressor 11, the operation is performed in the normal operation mode in which the target hot water temperature set at the start is maintained. After operating for a predetermined time at the target hot water temperature, when the detection values obtained by the flow meter 20F, the pressure gauge 20G, and the pump output detection means 23A are lower than the detection values during the previous operation, they are determined in advance. Operate at the target hot water temperature limit value.

  First, the target hot water temperature setting control function will be described with reference to FIG.

  FIG. 2 is a block diagram showing a target hot water temperature setting control function of the heat pump hot water supply apparatus according to the first embodiment of the present invention.

  The target hot water temperature determining means 40 has a flow rate comparing means 41 and a pump output comparing means 43.

  First, when the boiling operation is started, a relational expression between the pump output and the flow rate flowing through the water circuit is previously obtained, and the flow rate corresponding to the pump output detected by the pump output comparison unit 43 is calculated. The current flow rate is detected by the flow rate detection unit 20F, and the flow rate calculated from the pump output is compared by the flow rate comparison unit 41. As a result, when the current flow rate is low, the target hot water temperature setting means 44 limits the target hot water temperature.

  The limit value in the target hot water temperature setting means 44 is a predetermined hot water temperature value determined in advance, and the expansion valve opening manipulated variable determining means 45 opens the expansion valve from the value detected by the discharge refrigerant temperature detecting means 10B. Determine the degree. The expansion valve opening degree control means 46 controls the main expansion valve 13A based on the expansion valve opening degree operation amount determined by the expansion valve opening degree operation amount determining means 45.

  FIG. 3 is a flowchart showing a flow of determination of a target hot water temperature value of the heat pump hot water supply apparatus according to the first embodiment of the present invention. After the start of operation, the operation is performed in a normal operation mode that maintains the target hot water temperature set at the time of startup.

  First, at step 1, an operation elapsed timer is started. When the elapsed time a exceeds a predetermined time T at step 2, the flow rate of the water circuit flowing through the hot water supply heat exchanger is set at step 3. It is detected by the flow rate detection means. When the flow rate value detected in step 4 (current operation flow rate) is compared with the flow rate calculated from the relationship between the pump output and the flow rate, and the current operation flow rate is lower than the calculated operation flow rate (step 5) Is set to a predetermined value (target hot water temperature limit value). The target discharge refrigerant temperature is determined so as to reach the target hot water temperature limit value (step 6), and the expansion valve opening operation amount is determined (step 7).

  Further, although the flow rates are compared in the present embodiment, the comparison may be made by water pressure instead of the flow rate. In that case, a water pressure comparing means 42 is provided in the target hot water temperature determining means 40, and a water pressure detecting means 20G for detecting the water pressure in the water circuit is further provided. Then, the water pressure comparing means 42 compares the detected value obtained by the water pressure detecting means 20G with the detected value calculated from the relational expression between the water pressure and the pump output, and if the detected value is lower than the calculated detected value, The temperature setting means 44 limits the target hot water temperature.

  FIG. 4 is a flowchart for determining the target hot water temperature value based on the water pressure. After the start of operation, the operation is performed in a normal operation mode that maintains the target hot water temperature set at the time of startup.

  First, in step 1, an operation elapsed timer is started. In step 2, when the elapsed time a exceeds a predetermined time T, the pressure of the water circuit flowing through the hot water supply heat exchanger is set in step 3. Detected by water pressure detecting means. The water pressure value detected in step 4 (current operation water pressure) is compared with the water pressure calculated from the relationship between the pump output and the water pressure, and the current operation water pressure is lower than the calculated water pressure. If it is present (step 5), the target hot water temperature is set to a predetermined value (target hot water temperature limit value). The target discharge refrigerant temperature is determined so as to reach the target hot water temperature limit value (step 6), and the expansion valve opening operation amount is determined (step 7).

  Although the present embodiment has been described with the case of having a hot water storage tank, it may be an instantaneous water heater type heat pump hot water supply apparatus that discharges hot water heated by a hot water supply heat exchanger as it is.

  Further, the compressor 11 has a compressor configuration without an accumulator, and since there is no accumulator, it is possible to reduce the size and weight of the heat pump hot water supply body.

  Furthermore, the heat pump circuit is a supercritical heat pump cycle in which the pressure of the refrigerant is equal to or higher than the critical pressure. By heating the hot water or air, the refrigerant in the hot water heat exchanger is pressurized above the critical pressure. Therefore, it does not condense even if the temperature is lowered due to heat deprived by the water in the hot water heat exchanger. Therefore, it becomes easy to form a temperature difference between the refrigerant and water over the entire area of the heat exchanger for hot water supply, so that hot water can be obtained and the heat exchange efficiency can be increased.

  Furthermore, the refrigerant to be used is carbon dioxide, and by using relatively inexpensive and stable carbon dioxide for the refrigerant, the product cost can be suppressed and the reliability can be improved. In addition, carbon dioxide has an ozone depletion coefficient of zero and a global warming coefficient of about 1/700 of the alternative refrigerant HFC-407C, which is very small.

  Further, in the present embodiment, a relational expression between the pump output and the flow rate (water pressure) is previously stored, and the pump output is the same, but the flow rate calculated from the relational expression is below. The temperature of the hot water is limited, but it has a plurality of relational expressions in advance, and once it falls below the flow rate calculated from the relational expression, it has a low slope from the relational expressions that it had in advance. The durability of the heat exchanger for hot water supply can be further improved by selecting the equation and using it in the relational equation between the pump output and the flow rate in the future.

  Further, the relational expression is not limited, and there is no problem even if the relationship between a plurality of pump outputs and flow rates is mapped and stored.

  As described above, the present invention can provide a heat pump water heater that can quickly detect scale clogging and improve the durability of the heat exchanger for hot water supply, and can extend the service life. Although the heat pump type hot water heater has a hot water storage tank, it can also be applied to a heat pump type hot water heater that does not have a hot water storage tank and that can supply hot water directly from the hot water heat exchanger to the hot water supply terminal. .

The circuit block diagram of the heat pump hot-water supply apparatus in the 1st Embodiment of this invention The block diagram which shows the target hot water temperature setting control function of the heat pump hot water supply device A flowchart for determining a target hot water temperature value of the heat pump hot water supply apparatus. The flowchart which determines the target hot-water temperature value in other embodiment

Explanation of symbols

10 heat pump circuit 10B temperature sensor (discharge refrigerant temperature detection means)
DESCRIPTION OF SYMBOLS 11 Compressor 12 Hot water supply heat exchanger 12A Water piping 13A Main expansion valve 14 Evaporator 20 Hot water storage tank 20F Flow rate detection means 20G Water pressure detection means 23A Pump output detection means 40 Target hot water temperature determination means 41 Flow rate comparison means 42 Water pressure Comparison means 43 Pump output comparison means 44 Target hot water temperature setting means 45 Expansion valve opening operation amount determination means 46 Expansion valve opening degree control means

Claims (2)

A heat pump cycle in which a compressor, a hot water heat exchanger, an expansion valve, and an evaporator are sequentially connected in an annular manner by a refrigerant pipe; a hot water storage tank for storing hot water liquid; and the hot water supply from the lower part of the hot water storage tank A water circuit connected to the upper part of the hot water storage tank via a heat exchanger for use, a circulation pump for conveying hot water in the water circuit, a flow rate detecting means for detecting a flow rate in the water circuit, and A target hot water temperature setting means for setting a target hot water temperature after heat exchange in the hot water heat exchanger, and a pump output detection means for detecting an output of the circulation pump, and driving the circulation pump. Even when the output of the circulating pump detected by the pump output detecting means during operation is the same as the output of the circulating pump at the previous operation, the flow rate detected by the flow rate detecting means is reduced. Expediently, the heat pump hot water supply apparatus and performs restriction of the target hot water temperature. A heat pump cycle in which a compressor, a hot water heat exchanger, an expansion valve, and an evaporator are sequentially connected in an annular manner by a refrigerant pipe; a hot water storage tank for storing hot water liquid; and the hot water supply from the lower part of the hot water storage tank A water circuit connected to the upper part of the hot water storage tank via a heat exchanger for use, a circulation pump for conveying hot water in the water circuit, a water pressure detecting means for detecting the water pressure in the water circuit, A target hot water temperature setting means for setting a target hot water temperature after heat exchange in the hot water heat exchanger, and a pump output detection means for detecting an output of the circulation pump, and driving the circulation pump. Although the output of the circulation pump detected by the pump output detection means is the same as the output of the circulation pump at the previous operation, the water pressure detected by the water pressure detection means decreases. If that is the heat pump hot water supply apparatus and performs restriction of the target hot water temperature.

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