JP2012042177A - Heat pump type hot water generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat pump type hot water generator achieving high efficiency and high stability of the temperature of hot water.SOLUTION: The heat pump type hot water generator includes: a low temperature-side refrigerating cycle A successively connecting a compressor 1, a condenser 2, an expansion valve 3 and an evaporator 4 with a refrigerant pipeline; a high temperature-side refrigerating cycle B successively connecting a compressor 5, a condenser 6, an expansion valve 7 and an evaporator 8 with a refrigerant pipeline; and an intermediate heat exchanger 15 for heat exchanging between the evaporator of the high temperature-side refrigerating cycle and the condenser of the low temperature-side refrigerating cycle. The heat pump type hot water generator is configured to generate hot water by the condenser in the high temperature-side refrigerating cycle. The compressor of the low temperature-side refrigerating cycle includes a volume controllable compressor, and the volume of the compressor in the low temperature-side refrigerating cycle is controlled to obtain a target temperature of the compressor in the low temperature-side refrigerating cycle.

Description

  The present invention relates to a heat pump type hot water generator using a two-way refrigeration cycle, and particularly relates to one that produces hot hot water.

  Some heat pump type hot water generators use a two-way refrigeration cycle having a high-side refrigeration cycle and a low-side refrigeration cycle in order to produce high-temperature hot water. In such operation control of the two-way refrigeration cycle, in order to perform highly efficient and stable operation, the ratio of the pressure ratios of the compressors in the high-side refrigeration cycle and the low-side refrigeration cycle is set to a predetermined ratio. (See, for example, Patent Document 1).

JP 2009-133539 A

  In the operation control of the two-way refrigeration cycle described in Patent Document 1, since the refrigerant is generally different between the high-side refrigeration cycle and the low-side refrigeration cycle, appropriate pressure ratios are different. Also, the appropriate pressure ratio varies depending on the characteristics of the refrigerant or the compressor itself. For these reasons, even if the ratio between the pressure ratios of the plurality of refrigerant circuits is maintained at a predetermined ratio, each refrigerant circuit is not always operated at an appropriate pressure ratio. In addition, an appropriate ratio of the pressure ratios of the plurality of refrigerant circuits varies depending on various combinations. For this reason, it is difficult to obtain a high-efficiency heat pump type hot water generator using a two-way refrigeration cycle.

  In the case of use as a refrigeration system in which an evaporator of a low-source side refrigeration cycle is connected to the load side, the purpose is to control to a predetermined pressure range, while controlling the operating state based on the pressure ratio It is not impossible to control the pressure following the load at the same time.

  However, in the case of a heat pump type hot water generator that generates high-temperature water by connecting the condenser of the high-end refrigeration cycle to the load side, it is necessary to control the hot water temperature within a predetermined temperature range, but it is not necessarily unique. Are not related to each other, and it is difficult to simultaneously control the operation state and the hot water temperature based on the pressure ratio using the refrigerant pressure. The invention described in Patent Document 1 Is difficult to apply to a heat pump hot water generator.

  Also, the response speed of the hot water outlet temperature and the refrigerant pressure according to the operating state of the compressor is different, and the change speed of the refrigerant pressure is faster.Therefore, when the control based on the pressure ratio by the refrigerant pressure is performed, the hot water temperature There is also a problem of impairing stability.

  An object of the present invention is to obtain a heat pump type hot water generator capable of improving efficiency and improving the stability of hot water temperature.

  In order to solve the above problems, the present invention sequentially includes a low-source side refrigeration cycle in which a compressor, a condenser, an expansion means, and an evaporator are sequentially connected by a refrigerant pipe, and a compressor, a condenser, an expansion means, and an evaporator. A high-source side refrigeration cycle connected by refrigerant piping; and an intermediate heat exchanger for exchanging heat between the condenser of the low-source side refrigeration cycle and the evaporator of the high-source-side refrigeration cycle, and the high-source side refrigeration cycle In the heat pump type hot water generator configured to generate hot water using a condenser, a compressor of the low-source side refrigeration cycle is a compressor whose capacity can be controlled, and a condenser temperature of the low-source side refrigeration cycle is a target. The capacity control of the compressor of the low-source side refrigeration cycle is performed so as to reach a temperature.

  ADVANTAGE OF THE INVENTION According to this invention, while being able to achieve high efficiency, the heat pump type hot water generator which can also improve stability of warm water temperature can be obtained.

The refrigeration cycle block diagram which shows Example 1 of the heat pump type hot water generator of this invention. The diagram which shows the relationship between the condensing temperature of the condenser in a low element side refrigerating cycle, and the operating efficiency (COP) of a low element side refrigerating cycle. The diagram which shows the relationship between the evaporation temperature of the evaporator in a high refrigeration cycle, and the operating efficiency (COP) of a high refrigeration cycle. The diagram which showed the driving | operation efficiency (COP) of the high yuan side refrigeration cycle and the low yuan side refrigeration cycle on the same figure, and also showed the total operation efficiency which combined the driving efficiency of the high yuan side and the low yuan side. The refrigeration cycle block diagram which shows Example 2 of the heat pump type hot water generator of this invention.

  Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a configuration diagram of a refrigeration cycle showing Example 1 of the heat pump type hot water generator of the present invention. In the figure, A is a low-source side refrigeration cycle, and a compressor 1, a condenser 2, an expansion valve 3, and an evaporator 4 are sequentially connected by piping. B is a high-end refrigeration cycle, and is composed of a compressor 5, a condenser 6, an expansion valve 7, and an evaporator 8 sequentially connected by piping. Further, the condenser 2 in the low refrigeration cycle and the evaporator 8 in the high refrigeration cycle are configured to exchange heat with each other in the intermediate heat exchanger 15, thereby constituting a two-way refrigeration cycle. .
In addition, R410A etc. are suitable as a refrigerant | coolant of the said low side refrigeration cycle A, and R134a etc. are suitable as a refrigerant | coolant of the said high side refrigeration cycle B.

  In the low-source side refrigeration cycle A, the high-temperature and high-pressure gas refrigerant compressed by the compressor 1 is cooled by heat exchange with the evaporator 8 of the high-source side refrigeration cycle B in the condenser 2 to be condensed and liquefied. The condensed and liquefied high-pressure liquid refrigerant is decompressed by an expansion valve (expansion means) 3 and then evaporated and exchanged with the outside air in an evaporator 4 to form a low-temperature and low-pressure gas refrigerant. This constitutes the refrigeration cycle.

  Similarly, also in the high-source side refrigeration cycle B, the high-temperature and high-pressure gas refrigerant compressed by the compressor 5 is cooled and condensed into hot water whose load-side temperature is reduced in the condenser 6. The condensed and liquefied high-pressure liquid refrigerant is decompressed by an expansion valve (expansion means) 7 and then evaporated by exchanging heat with the condenser 2 of the low-source side refrigeration cycle A by an evaporator 8 to produce a low-temperature and low-pressure gas refrigerant. Thus, a refrigeration cycle returning to the compressor 5 is configured again.

  As the compressor 1 of the low-source side refrigeration cycle A, a variable-speed compressor that can control the rotational speed by an inverter 9 is used. Further, 12 is an outside air temperature sensor for detecting the outside air temperature, 13 is a low side condensing temperature sensor for detecting the temperature of the refrigerant discharged from the condenser 2 of the low side refrigeration cycle, and 14 is a high side refrigeration cycle B. This is a high-side hot water outlet temperature sensor for detecting the outlet temperature of hot water heated by the condenser 6. The temperature data detected by these temperature sensors 12 to 14 is sent to the control device 11, and the control device 11 determines the rotational speed of the low-source compressor 1 via the inverter 9 based on these temperature information. Control or ON / OFF control of the compressor 5 on the high side.

  That is, the low-side compressor 1 controls the rotational speed (capacity control) so that the temperature of the low-side condenser 2 becomes the target temperature based on the temperature data detected by the low-side condensation temperature sensor 13. Is done. Further, the high-end compressor 5 is controlled to turn on / off so that the outlet temperature of the hot water falls within a predetermined range (set temperature) based on the temperature data detected by the high-end hot water outlet temperature sensor 14. Is done. As described above, in this embodiment, the capacity control of the compressor of the low-side refrigeration cycle is performed so that the temperature of the condenser of the low-side refrigeration cycle becomes the target temperature, and in the high-side refrigeration cycle, The compressor is operated and controlled according to the outlet temperature of the hot water from the condenser of the high refrigeration cycle, and the compressor of the high refrigeration cycle and the compressor of the low refrigeration cycle are controlled independently. Is done.

  FIG. 2 is a graph showing the relationship between the condensation temperature of the condenser 3 in the low-side refrigeration cycle A and the operating efficiency (COP) of the low-side refrigeration cycle. When performing operation to supply hot water as a heat pump type hot water generator, the operation efficiency (COP) in the low-source side refrigeration cycle A is higher as the condensation temperature is lowered, as shown by the curve C in FIG. I understand that

  FIG. 3 is a diagram showing the relationship between the evaporation temperature of the evaporator 8 in the high-side refrigeration cycle B and the operating efficiency (COP) of the high-side refrigeration cycle. When performing operation to supply hot water as a heat pump type hot water generator, the operation efficiency (COP) in the high-side refrigeration cycle B increases as the evaporation temperature increases, as shown by the curve D in FIG. I understand that

  FIG. 4 shows the operation efficiency (COP) of the high-source side refrigeration cycle and the operation efficiency (COP) of the low-source side refrigeration cycle shown in FIG. It is the diagram which also showed the total operation efficiency (COP). In FIG. 4, a curve C1 corresponds to the curve C indicating the operation efficiency in the low-source side refrigeration cycle A shown in FIG. 2, and is an operation efficiency curve when the outside air temperature is 5 ° C. A curve D1 corresponds to the curve D indicating the operation efficiency in the high-side refrigeration cycle B shown in FIG. 3, and is a curve indicating the operation efficiency when the hot water outlet temperature is 60 ° C. Further, the total operating efficiency (COP) of the operating efficiency (curve C1) on the low element side and the operating efficiency (curve D1) on the high element side is represented by a curve E. From this total operating efficiency curve E, the operating conditions that optimize the operating efficiency (COP) of the entire device as a heat pump hot water generator are the operating efficiency curve C of the low-source side refrigeration cycle and the operating efficiency of the high-source side refrigeration cycle. It turns out that it becomes the circumference | surroundings of the driving point (alpha) where the curve D crossed. That is, in order to operate at the operating point α, the target temperature is set so that the condensation temperature of the low-source side refrigeration cycle at that time (approximately equal to the evaporation temperature of the high-source side refrigeration cycle) is t1, By controlling the number of revolutions of the compressor 1 on the low-source side, it is possible to substantially maximize the operating efficiency (COP) of the entire device.

  In the heat pump hot water generator, the set temperature (or set temperature range) of the hot water temperature to be supplied to the load may be changed depending on the load condition. At this time, the operating efficiency of the high-source side refrigeration cycle increases the condensation temperature in the high-side refrigeration cycle when the hot water outlet temperature is increased, so that the higher the condensation temperature is, as in the relationship shown in FIG. Efficiency is lowered. That is, as shown in FIG. 4, when the hot water outlet temperature is set to 70 ° C., the operating efficiency curve changes to D2, and when it is set to 80 ° C., the operating efficiency curve changes to D3. When the set temperature of the hot water is changed in this way, the operating efficiency curve also changes, so that the operating conditions that optimize the operating efficiency of the entire device also change. For example, when the outside air temperature remains at 5 ° C. and the set temperature of the hot water is raised to 70 ° C., the operating conditions that optimize the operating efficiency of the entire device are the operating efficiency curve C1 of the low-source side refrigeration cycle, Since it is in the vicinity of the operating point β where the operating efficiency curve D2 of the former-side refrigeration cycle intersects, it is possible to improve the operating efficiency of the entire device by changing the operating point from α to β. In order to operate with the operating point changed to β, the target temperature may be set so that the condensation temperature of the low-source side refrigeration cycle becomes t2, and the low-side compressor 1 may be controlled in rotational speed.

  On the other hand, when the set temperature of the hot water remains at 60 ° C. and the outside air temperature changes from 5 ° C. to 10 ° C., the operating condition that optimizes the operating efficiency of the entire device is the operating efficiency curve C2 of the low-source side refrigeration cycle. Since it is around the operating point γ where the operating efficiency curve D1 of the high-source side refrigeration cycle intersects, the operating efficiency of the entire device can be improved by changing the operating point from α to γ. In order to operate with the operating point changed to γ, the target temperature is changed so that the condensation temperature of the low-side refrigeration cycle is changed from t1 to t2, and the rotational speed of the low-side compressor 1 is controlled.

  According to the present embodiment described above, the target temperature of the condenser in the low refrigeration cycle is determined based on the outside air temperature and the set temperature of hot water produced by the condenser of the high refrigeration cycle, The condensing temperature of the low-source side refrigeration cycle is such that the total operating efficiency (COP) that combines the operating efficiency of the low-source side refrigeration cycle and the operating efficiency of the high-source-side refrigeration cycle is the highest operating point. Since the compressor of the low-source side refrigeration cycle is controlled so as to reach this condensation temperature, it is possible to achieve high efficiency and not to control based on the pressure ratio but to the condensation temperature. Since it is controlled based on this, a heat pump hot water generator capable of enhancing the stability of the hot water temperature can be obtained.

  Further, according to the present embodiment, the compressors 1 and 5 of the high-side refrigeration cycle A and the low-side refrigeration cycle B are independently controlled based on the temperatures related to the respective condensers. In the former-side refrigeration cycle B, the hot water temperature can be controlled within a predetermined temperature range (target temperature) in accordance with the load-side situation. On the other hand, in the low source side refrigeration cycle A, the rotation speed control of the compressor 1 is performed so as to maintain the condensation temperature of the condenser in the low source side refrigeration cycle at a predetermined temperature. Therefore, it is possible to control both the low-source side refrigeration cycle A and the high-source side refrigeration cycle B so as to be in an operating state with higher operating efficiency. That is, the compressor 5 is operated with priority given to following the state of the load for the high-source side refrigeration cycle B, and the condensation temperature at which the efficiency of the entire device becomes higher is set for the low-source side refrigeration cycle A. By controlling the compressor 1 so as to maintain the condensing temperature, it is possible to achieve both the operation according to the load condition and the high efficiency of the equipment.

  In particular, according to this embodiment, the compressor 1 of the low-source side refrigeration cycle A can finely adjust the rotational speed so that the condensation temperature of the condenser in the low-source side refrigeration cycle is maintained at a predetermined temperature. Higher-accuracy control can be easily performed, and operation with further improved control stability is possible as compared with the conventional control based on the pressure ratio that varies depending on the operation state.

  FIG. 5 is a configuration diagram of a refrigeration cycle showing Embodiment 2 of the present invention, and the portions denoted by the same reference numerals as those in FIG. 1 indicate the same or corresponding portions. In this embodiment, the compressor 5 of the high-side refrigeration cycle B is also controlled as a variable speed compressor driven by an inverter 10. That is, the hot water outlet temperature from the condenser of the high-side refrigeration cycle is detected by a high-side hot water outlet temperature sensor, and compression in the high-side refrigeration cycle is performed so that the hot water outlet temperature falls within a predetermined range. The number of revolutions of the machine is controlled. Other configurations and controls are the same as those in the first embodiment, and a description thereof will be omitted.

  According to the present embodiment, the same effect as that of the embodiment shown in FIG. 1 can be obtained, and the compressor 5 of the high-side refrigeration cycle can also finely adjust the rotation speed, so that the hot water having a more stabilized temperature can be obtained. Can be supplied to the load. In addition, since the compressor capacity can be finely adjusted according to the load-side situation, the operation efficiency (COP) of the entire device can be further improved.

  In Examples 1 and 2 described above, both the low-side refrigeration cycle and the high-side refrigeration cycle have been described with the operation mode having no four-way switching valve as a single refrigeration cycle. The present invention can be similarly implemented even when at least one of the refrigeration cycles on the high-end side is configured by a refrigeration cycle having a four-way switching valve.

A Low refrigeration cycle B High refrigeration cycle 1, 5 Compressor 2 Low refrigeration cycle condenser 3, 7 Expansion valve (expansion means)
4 Evaporator 6 Condenser 8 Evaporators 9 and 10 in the high-end refrigeration cycle Inverter 11 Control device 12 Outside air temperature sensor 13 Low-end side condensing temperature sensor 14 High-end hot water outlet temperature sensor 15 Intermediate heat exchanger.

Claims (7)

A low-source side refrigeration cycle in which a compressor, a condenser, an expansion means, and an evaporator are sequentially connected by a refrigerant pipe; and a high-source side refrigeration cycle in which a compressor, a condenser, an expansion means, and an evaporator are sequentially connected by a refrigerant pipe; An intermediate heat exchanger for exchanging heat between the condenser of the low original refrigeration cycle and the evaporator of the high original refrigeration cycle is configured to generate hot water by the condenser of the high original refrigeration cycle. In the heat pump hot water generator,
The compressor of the low-source side refrigeration cycle is a compressor whose capacity can be controlled,
The heat pump hot water generator is characterized in that the capacity of the compressor of the low-source side refrigeration cycle is controlled so that the temperature of the condenser of the low-side refrigeration cycle becomes a target temperature.   The heat pump hot water generator according to claim 1, wherein the target temperature of the condenser in the low-source side refrigeration cycle is based on an outside air temperature and a set temperature of hot water produced by the condenser of the high-source side refrigeration cycle. A heat pump type hot water generator characterized by being determined.   The heat pump hot water generator according to claim 2, wherein the total operating efficiency of the operating efficiency of the high-source-side refrigeration cycle and the operating efficiency of the low-source-side refrigeration cycle is the operating point where the total operating efficiency is the highest. A heat pump type hot water generator characterized in that the condensation temperature of the low-source side refrigeration cycle is determined, and the capacity of the compressor of the low-source side refrigeration cycle is controlled so as to reach this condensation temperature.   The heat pump type hot water generator according to any one of claims 1 to 3, wherein the compressor in the low-source side refrigeration cycle is an inverter-driven variable speed compressor, and the condenser temperature in the low-source side refrigeration cycle And the number of revolutions of the compressor is controlled so that the detected temperature of the condenser is maintained at a predetermined temperature.   The heat pump type hot water generator according to any one of claims 1 to 4, wherein the compressor in the high-source side refrigeration cycle is controlled in accordance with an outlet temperature of hot water from a condenser in the high-source side refrigeration cycle. A heat pump type hot water generator, wherein the compressor of the high-end side refrigeration cycle and the compressor of the low-end side refrigeration cycle are independently controlled.   6. The heat pump hot water generator according to claim 5, wherein an outlet temperature of hot water from a condenser of the high-end refrigeration cycle is detected, and the high-end refrigeration cycle is set so that the hot water outlet temperature falls within a predetermined range. A heat pump type hot water generator characterized by ON / OFF control of a compressor in   The heat pump hot water generator according to claim 5, wherein the compressor in the high-side refrigeration cycle is an inverter-driven variable speed compressor, and the outlet temperature of hot water from the condenser in the high-side refrigeration cycle , And the number of revolutions of the compressor in the high-side refrigeration cycle is controlled so that the temperature of the hot water outlet is within a predetermined range.

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