JP2014167352A - Heating system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly efficient heating system capable of discharging high temperature hot water while securing a necessary amount of hot water by utilizing characteristics of a new cooling medium.SOLUTION: A heating system includes: a first refrigeration cycle 4 including a first water-cooling medium heat exchanger 4a for exchanging heat between water and a cooling medium, and using an HFC cooling medium which has unsaturated carbon as the cooling medium; a second refrigeration cycle 5 including a second water-cooling medium heat exchanger 5a, and using a cooling medium chosen from one of an HFC cooling medium which does not have unsaturated carbon and a natural cooling medium as the cooling medium; and a water pipe 3 for circulating water in a water heat exchange pipe of the first and the second water-cooling medium heat exchangers 4a and 5a. Also, the first water-cooling medium heat exchanger 4a and the second water-cooling medium heat exchanger 5a are connected in parallel to the water pipe 3, water is heated by the first water-cooling medium heat exchanger 4a and the second water-cooling medium heat exchanger 5a respectively, the water sent out from the first water-cooling medium heat exchanger 4a and the second water-cooling medium heat exchanger 5a are made confluent, and it is supplied to a utilization side.

Description

  Embodiments of the present invention relate to a heating system.

In recent years, CO ₂ reduction has become an urgent task from the viewpoint of preventing global warming, and as part of this, the use of a heat pump system as an alternative to a combustion apparatus has been studied. For example, introduction of a high-temperature heat pump heating system as an alternative to boilers in industrial processes and introduction of a heat pump heating system as an alternative to household gas / kerosene water heaters.

Currently used heat pump heating systems include those using CO ₂ refrigerant as a refrigerant, those using R410A, and those using R134a. There is a request that the return water temperature is 50 ° C. or higher at ˜90 ° C. For cold districts, there is a demand for an outside temperature of -20 ° C and a hot water temperature of 80 ° C. Since these demands are severe operating conditions for the heat pump heating system, the current situation is that the spread to these areas has not progressed much.

  The heat pump heating system that is currently popular has the property that, as the incoming water temperature increases, the operating pressure on the high-pressure side increases and the compressor discharge temperature also increases. Also, the operating efficiency decreases as the incoming water temperature increases. Since the discharge temperature of the compressor has an allowable limit in terms of reliability, the temperature at which hot water can be discharged decreases as the incoming water temperature increases. On the other hand, as the outside air temperature decreases, the compressor discharge temperature also increases, so that the temperature at which hot water can be discharged decreases as the outside air temperature decreases.

The temperature at which hot water can be discharged under such conditions varies depending on the refrigerant used, and R134a can achieve a higher hot water temperature than CO ₂ refrigerant or R410A, but at the same hot water temperature, the efficiency is slightly lower. . In addition, since R134a has a gas density lower than that of the CO ₂ refrigerant and R410A, there is a disadvantage that the equipment such as the diameter of the refrigerant pipe is increased.

  Therefore, as a means for solving these problems, a heat pump heating system (hereinafter referred to as conventional 1) that constitutes a dual refrigeration cycle that uses R134a for the high temperature side refrigeration cycle and R410A for the low temperature side refrigeration cycle can be considered. ing.

  In addition, a series-connected heating system (hereinafter referred to as “conventional 2”) in which water is preheated to a medium temperature in a refrigeration cycle using R410A and then heated to a final required temperature by a refrigeration cycle using R134a is considered. It has been.

JP 2007-198693 A

  However, in the conventional two-way refrigeration cycle configuration, high-temperature hot water can be discharged, but there is a problem that the efficiency of the entire system is lowered because the efficiency loss in the intermediate heat exchanger is large.

  On the other hand, in the conventional series-connected heating system, there is no irreversible efficiency loss due to the intermediate heat exchanger, and the efficiency is higher than that of the two-way refrigeration cycle if the preheating temperature by the pre-stage side refrigeration cycle is optimized. However, since the incoming water temperature of the refrigeration cycle on the rear stage side (R134a side) is high, the temperature at which the hot water can be discharged is lower than in the dual cycle.

  By the way, in recent years, HFC (hydrofluorocarbon) refrigerant having unsaturated carbon having a GWP (global warming potential) of one digit has been developed, and proposals for use in car air conditioners and stationary air conditioners have been made. Although this HFC refrigerant has been developed as an alternative to R134a, it has a feature that the discharge temperature of the compressor is low, and when the present inventor examined its use in a heat pump heating system, hot water discharge hotter than R134a. And obtained new knowledge that it is possible to obtain hot water close to 100 ° C.

  The problem to be solved by the present invention is to provide a high-efficiency heating system capable of high-temperature hot water discharge while ensuring the necessary amount of hot water using the characteristics of the HFC refrigerant.

  The heating system of the present embodiment includes a first refrigeration cycle that includes a first water-refrigerant heat exchanger for exchanging heat between water and a refrigerant, and uses an HFC refrigerant having unsaturated carbon as a refrigerant. A second refrigeration cycle using a refrigerant selected from any one of an HFC refrigerant and a natural refrigerant having no water and an unsaturated carbon as a refrigerant, and the first and second water- And a water pipe for circulating water through the water heat exchange pipe of the refrigerant heat exchanger.

  In the present embodiment, the first water-refrigerant heat exchanger and the second water-refrigerant heat exchanger are connected in parallel to the water pipe, and the first water-refrigerant heat exchanger and the second water are connected. -Water is each heated with a refrigerant | coolant heat exchanger, the water sent from the 1st water-refrigerant heat exchanger and the 2nd water-refrigerant heat exchanger is merged, and it supplies to a utilization side.

The system block diagram of the heating system which concerns on 1st Embodiment. The graph which shows the effect of 1st Embodiment shown in FIG. The system block diagram of the heating system which concerns on 2nd Embodiment.

  Hereinafter, the present embodiment will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same or an equivalent part in several drawing.

(First embodiment)
FIG. 1 is a system configuration diagram of a heating system according to the first embodiment. As shown in FIG. 1, the heating system 1 is a heat pump type heating system, and a first water-refrigerant of a first refrigeration cycle 4 is connected to a water pipe 3 of a hot water storage tank 2 which is an example of the use side. The heat exchanger 4a and the second water-refrigerant heat exchanger 5a of the second refrigeration cycle 5 are connected in parallel.

  The hot water storage tank 2 is a tank having a required capacity for storing hot water heated by the first and second refrigeration cycles 4 and 5, and a water pipe for circulating water or hot water by connecting the hot water inlet IN and the hot water outlet OUT. 3 is provided.

  The water pipe 3 includes a first water branch pipe 3a for sending hot water from the hot water storage tank 2 to a water heat exchange pipe (not shown) of the first water-refrigerant heat exchanger 4a, and the first water branch pipe 3a. And a second water branch pipe 3b that feeds water to a water heat exchange pipe (not shown) of the second water-refrigerant heat exchanger 5a.

  These first and second water branch pipes 3a and 3b are respectively provided with first and second flow control valves 6 and 7, respectively. Furthermore, the 1st, 2nd water branch pipe 3a, 3b forms the warm water mixing part M in the connection part of the warm water exit side. In addition, the water pipe 3 is provided with a water supply pump 8 in the middle thereof, and the hot water from the hot water storage tank 2 is supplied to the water heat exchange pipes of the first and second water-refrigerant heat exchangers 4a and 5a. To do.

  The first refrigeration cycle 4 includes a first compressor 4b, a first four-way valve 4c, a refrigerant heat exchange pipe (not shown) of the first water-refrigerant heat exchanger 4a, a first expansion valve 4d, and air cooling, for example. A first outdoor heat exchanger 4e of the type is connected by a first refrigerant pipe 4f to constitute a refrigeration cycle in which an HFC (hydrofluorocarbon) refrigerant having unsaturated carbon is circulated.

  Examples of HFC refrigerants having unsaturated carbon include HFO1234yf and HFO1234ze, which are low-pressure refrigerants having a lower pressure at the same saturation temperature than HFC refrigerants having no unsaturated carbon, which will be described later. In this embodiment, HFO1234yf is used as the HFC refrigerant having unsaturated carbon.

  For this reason, the first refrigeration cycle 4 is capable of hot hot water at 100 ° C., for example, at an evaporation temperature of −20 ° C.

  On the other hand, the second refrigeration cycle 5 includes a second compressor 5b, a second four-way valve 5c, a refrigerant heat exchange pipe (not shown) of the second water-refrigerant heat exchanger 5a, a second expansion valve 5d, and a second The two outdoor heat exchangers 5e are connected by a second refrigerant pipe 5f to constitute a refrigeration cycle that circulates an HFC refrigerant having no unsaturated carbon. In this embodiment, R410A is used as an HFC refrigerant that does not have unsaturated carbon. For this reason, the second refrigeration cycle 5 can perform hot water extraction at an intermediate temperature (for example, 60 ° C. to 70 ° C.) with high efficiency.

  Further, the operating frequency of the first and second compressors 4b and 5b and the opening degree of the first and second flow rate regulating valves 6 and 7 are controlled by the hot water control means S, and the first and second compressions are performed. The temperature and flow rate of hot water sent from the first and second water-refrigerant heat exchangers 4a and 5a depending on the operating frequency of the machines 4b and 5b and the opening degree of the first and second flow rate control valves 6 and 7. Is to be controlled.

  Next, the operation of the heating system 1 will be described.

  When the first and second refrigeration cycles 4 and 5 and the water pump 8 are operated, the hot water in the hot water storage tank 2 is pumped from the hot water outlet OUT at the lower part of FIG. Further, the first and second water branch pipes 3a and 3b of the first and second refrigeration cycles 4 and 5 are flowed according to the valve opening ratios of the first and second flow control valves 6 and 7, respectively. Distributed to.

  The hot water flowing through the water heat exchange pipe of the first water-refrigerant heat exchanger 4a on the first refrigeration cycle 4 side is heated to, for example, 90 ° C. by the refrigerant flowing through the refrigerant heat exchange pipe, It flows into the mixing part M.

  On the other hand, the hot water passing through the water heat exchange pipe of the second water-refrigerant heat exchanger 5a of the second refrigeration cycle 5 is heated to, for example, 70 ° C. hot water by the refrigerant flowing through the refrigerant heat exchange pipe. It flows into the warm water mixing part M.

  Therefore, in this warm water mixing section M, the 90 ° C. warm water from the first refrigeration cycle 4 and the 70 ° C. warm water from the second refrigeration cycle 5 are mixed, so that the flow rates of both warm water are equal. In this case, the temperature becomes 80 ° C., and the water is supplied into the hot water storage tank 2 and stored. Hot water heated to a predetermined temperature in the hot water storage tank 2 is supplied to a hot water supply terminal (not shown).

  The hot water set temperature of the first and second refrigeration cycles 4 and 5 is controlled by the operating frequency of the first and second compressors 4b and 5b and the opening degree of the first and second flow control valves 6 and 7. It is appropriately controlled according to the flow rate of the hot water.

  Therefore, according to this warming system 1, while setting the hot water supply hot water temperature by the side of the 1st refrigeration cycle 4 in which high temperature hot water discharge is possible, the hot water supply by the side of the 2nd freezing cycle 5 where the temperature which can be discharged hot water is low is set. By setting the temperature low and increasing the delivery hot water flow rate, it is possible to ensure the required amount of hot water required from the use side even at the time of high temperature hot water.

  FIG. 2 is a graph showing an example of COP (coefficient of performance) of the heating system 1 according to the present embodiment configured as described above in comparison with the above-described conventional examples 1 and 2 and the like. That is, FIG. 2 shows that the evaporation temperature of the first and second outdoor heat exchangers 4e and 5e acting as an evaporator is −20 ° C., the temperature of water supplied to the hot water storage tank 2 from the outside is 10 ° C. When operating temperature is 80 ° C., the COP (coefficient of performance) of the heating system 1 of this embodiment and the conventional examples 1 and 2 is shown on the vertical axis, and the low-pressure refrigerant with respect to the hot water supply load of the entire system The horizontal axis shows the load ratio of the side refrigeration cycle. Therefore, the entire hot water supply load is “1” on the horizontal axis.

  Since the conventional example 1 has a two-way refrigeration cycle configuration in which R134a is used for the high temperature side refrigeration cycle and R410A is used for the low temperature side refrigeration cycle, there is no concept of the load ratio of the refrigeration cycle on the low pressure refrigerant side to the hot water supply load. In FIG. 2, it is depicted as a COP constant (for example, 2.73) line as indicated by a broken line.

  In addition, the conventional example 2 which is a serial connection heating system in which water is preheated to about a medium temperature in the R410A side refrigeration cycle and then heated to a final required temperature using the R134a side refrigeration cycle has the same saturation temperature. When the load ratio of the refrigeration cycle on the high temperature side using R134a, which is a low-pressure refrigerant whose pressure at R4 is lower than R410A, is gradually increased, for example, from about 0.43 to about 0.71, the COP is also increased from about 2.75 to about Gradually rises to 2.85.

  Further, the “conventional configuration” in FIG. 2 uses the same two types of refrigerants as in the present embodiment, for example, the low-pressure refrigerants HFO1234yf and R410A, and each water-refrigerant heat exchange of the two refrigeration cycles using these refrigerants. In this case, the load ratio of the refrigeration cycle on the low-pressure refrigerant (HFO1234yf) side is about 0.43 to about 0.00. When gradually increased to 71, the COP gradually increases from about 2.66 to about 2.85.

  On the other hand, according to the present embodiment, the COP is 2.9 or more in the entire region where the load ratio on the low-pressure refrigerant side is about 0.43 to about 0.71, and from the conventional examples 1 and 2 and the “conventional configuration” Also shows a high COP.

  That is, in the first refrigeration cycle 4 using the HFC refrigerant having unsaturated carbon, since the density of this refrigerant is small, when increasing the amount of hot water delivered, the system is increased in size, but the delivered hot water Since it is easy to increase the temperature, the delivery hot water temperature is set higher than the delivery hot water temperature of the second refrigeration cycle 5, for example, 90 ° C.

On the other hand, natural refrigerants such as R410A and CO ₂ that do not have unsaturated carbon have a high density, so it is easy to increase the amount of hot water delivered without increasing the size of the system, but the temperature of the delivered hot water is about It is not easy to increase the temperature as in the first refrigeration cycle 4.

  For this reason, in the second refrigeration cycle 5, the temperature of the hot water to be sent is stopped at an intermediate temperature (for example, 60 ° C. to 70 ° C.) lower than the temperature of the hot water to be sent in the first refrigeration cycle 4 to mainly secure the amount of hot water delivered. I am trying.

  And by mixing the hot water with different temperatures sent from the first and second refrigeration cycles 4 and 5 in this way in the hot water mixing section M, hot water required at the use side can be discharged. In addition, it is possible to ensure the required amount of hot water at the time of high temperature hot water discharge, and as can be seen from FIG. 2, the COP (coefficient of performance) can be increased, and the efficiency can be improved. it can.

  In addition, since the first and second refrigeration cycles 4 and 5 have different delivery hot water temperatures, each upper limit of the sendable hot water temperature determined for each type of refrigerant depending on the evaporation temperature and the temperature of the supplied water. It can be easily adapted to: For this reason, generation | occurrence | production of the malfunction of the heating system 1 can be reduced and the improvement of reliability can be aimed at.

  Furthermore, since the HFC refrigerant containing unsaturated carbon used in the first refrigeration cycle 4 does not adversely affect the organic material and the like, the same material as the conventional one should be used for the components of the first compressor 4b. Therefore, the cost of the system can be reduced.

(Second Embodiment)
The second embodiment is a control method for controlling the temperature of hot water discharged from the heating system 1 according to the first embodiment to a hot water temperature T requested by the user. Hereinafter, this control method will be described.

First, the flow rate of hot water required by the use side (hot water storage tank 2) (use side required hot water flow rate) is W, the same temperature (use side required hot water temperature) is T, and the first and second refrigeration cycles from the hot water storage tank 2 side. Assuming that the temperature of the return water, which is the water supplied to 4, 5, is Tin, it is sent from the first and second water-refrigerant heat exchangers 4a, 5a of the first and second refrigeration cycles 4, 5. The following formula is established between the flow rates W1 and W2 of the hot water and the temperatures T1 and T2 of the hot water sent from the first and second water-refrigerant heat exchangers 4a and 5a.
[Equation 1]
W = W1 + W2 (1)
W (T-Tin) = W1 (T1-Tin) + W2 (T2-Tin) (2)
However, T1> T2.

  The following first temperature set value A1 is determined based on the temperature at which the second refrigeration cycle 5 can be operated efficiently, and the second temperature set value A2 is the maximum temperature at which the second refrigeration cycle 5 can discharge hot water. Based on the above.

(1) Therefore, when the hot water temperature T requested by the user is lower than the first temperature set value A1 (T <A1), the hot water control means S uses the hot water flow rate W2 of the second water-refrigerant heat exchanger 5a. The opening degree of the first and second flow rate control valves 6 and 7 is controlled so that the flow rate is larger than the warm water flow rate W1 of the first water-refrigerant heat exchanger 4a (W2> W1). Furthermore, the hot water temperature at the time of mixing in the hot water mixing unit M from the first and second water-refrigerant heat exchangers 4a and 5a is the hot water temperature required by the user (user-side required hot water temperature) T Thus, the warm water temperatures T1 and T2 of the first and second water-refrigerant heat exchangers 4a and 5a are obtained from the above formulas (1) and (2).
And the operating frequency of the 1st, 2nd compressor 4b, 5b is controlled so that the warm water temperature sent from the 1st and 2nd water-refrigerant heat exchangers 4a, 5a may become T1, T2.

(2) When the hot water temperature T requested by the user side is higher than the first temperature set value A1 and lower than the second temperature set value A2 (A1 <T <A2), the hot water control means S Of the first and second flow rate control valves 6 and 7 so that the warm water flow rate W2 of the water-refrigerant heat exchanger 5a is equal to the warm water flow rate W1 of the first water-refrigerant heat exchanger 4a (W2 = W1). Control the opening. Furthermore, the above formula (1) is set so that the hot water temperature at the time of mixing in the hot water mixing section M from the first and second water-refrigerant heat exchangers 4a and 5a becomes the use-side required hot water temperature T. And (2), the delivery temperatures T1 and T2 of the first and second refrigeration cycles 4 and 5 are obtained.
And the operating frequency of the 1st, 2nd compressor 4b, 5b is controlled so that the warm water temperature sent from the 1st and 2nd water-refrigerant heat exchangers 4a, 5a may become T1, T2.

(3) When the hot water temperature T requested by the user is equal to or higher than the second temperature set value A2 (T> A2), the hot water control means S sets the hot water flow rate W2 of the second water-refrigerant heat exchanger 5a to the first. The opening degree of the first and second flow rate regulating valves 6 and 7 is controlled so as to be smaller than the warm water flow rate W1 of the water-refrigerant heat exchanger 4a (W2 <W1). Furthermore, the above formula (1) and the formula (1) are set so that the hot water temperature at the time of mixing in the hot water / hot water mixing section M from the first and second water-refrigerant heat exchangers 4a and 5a becomes the user-side required hot water temperature T. From (2), the delivery temperatures T1, T2 of the first and second water-refrigerant heat exchangers 4a, 5a are obtained.
And the operating frequency of the 1st, 2nd compressor 4b, 5b is controlled so that the warm water temperature sent from the 1st and 2nd water-refrigerant heat exchangers 4a, 5a may become T1, T2.

  Also in the second embodiment, the same effect as that of the first embodiment can be obtained, and hot water having a temperature according to a request on the use side can be easily supplied with higher efficiency.

(Third embodiment)
3rd Embodiment is a control method in the case of performing heat insulation operation in the heating system 1 which concerns on the said 1st Embodiment. In the following, the first temperature set value B1 is determined based on the temperature at which the second refrigeration cycle 5 can be operated efficiently, and the second temperature set value B2 is set so that the second refrigeration cycle 5 can be operated. Determined based on return water temperature.

  That is, there is almost no consumption of the hot water of the hot water storage tank 2 on the use side, and the warm water temperature difference between the inlet IN side and the outlet OUT side of the hot water storage tank 2 is small (for example, 20 ° C. to 30 ° C.) Based on the return water temperature TR which is the temperature of the water supplied to the first and second water-refrigerant heat exchangers 4a and 5a by the control means S, control is performed as follows.

(1) When the return water temperature TR from the use side is lower than the first temperature set value B1 (TR <B1), the hot water flow rate W2 of the second water-refrigerant heat exchanger 5a is set to the first water- The opening degree of the first and second flow rate adjusting valves 6 and 7 is controlled so as to be larger than the warm water flow rate W1 of the refrigerant heat exchanger 4a (W2> W1). Furthermore, the above formula (1) and the formula (1) are set so that the hot water temperature at the time of mixing in the hot water mixing unit M from the first and second water-refrigerant heat exchangers 4a and 5a becomes the use-side required hot water temperature T. The hot water temperatures T1, T2 of the first and second water-refrigerant heat exchangers 4a, 5a are obtained from (2).
And the operating frequency of the 1st, 2nd compressor 4b, 5b is controlled so that the warm water temperature sent from the 1st, 2nd water-refrigerant heat exchanger 4a, 5a becomes T1, T2.

(2) When the return water temperature TR from the use side is higher than the first temperature set value B1 and lower than the second temperature set value B2 (B1 <TR <B2), the second water-refrigerant The opening degree of the first and second flow rate control valves 6 and 7 is set so that the warm water flow rate W2 of the heat exchanger 5a is equal to the warm water flow rate W1 of the first water-refrigerant heat exchanger 4a (W2 = W1). Control. Furthermore, the above formulas (1) and (1) are set so that the hot water temperature at the time of mixing in the hot water mixing section M from the first and second water-refrigerant heat exchangers 4a and 5a becomes the user-side required hot water temperature T. The hot water temperatures T1, T2 of the first and second water-refrigerant heat exchangers 4a, 5a are obtained from 2).
And the operating frequency of the 1st, 2nd compressor 4b, 5b is controlled so that the warm water temperature sent from the 1st, 2nd water-refrigerant heat exchanger 4a, 5a becomes T1, T2.

  (3) When the return water temperature TR from the use side is equal to or higher than the second temperature set value B2 (TR> B2), the hot water flow rate W2 of the second water-refrigerant heat exchanger 5a is set to zero, The opening degree of the first and second flow rate control valves 6 and 7 is controlled so that the hot water flow rate W1 of the water-refrigerant heat exchanger 4a becomes the use-side required hot water flow rate W (W1 = W). Furthermore, the operating frequency of the first compressor 4b is controlled by only the first water-refrigerant heat exchanger 4a so that the mixed hot water temperature in the hot water mixing section M becomes the use-side required hot water temperature T. The hot water temperature T1 of the first water-refrigerant heat exchanger 4a is set to be higher than the hot water temperature T2 of the second water-refrigerant heat exchanger 5a (T1> T2) as described above. is there.

  With this control method, the effects of the first embodiment can be obtained, and a highly efficient heat retaining operation corresponding to a wide range of hot water temperatures is possible.

(Fourth embodiment)
The heating system 1A according to the fourth embodiment includes the first refrigeration cycle 4 and the second refrigeration cycle 5 according to the first embodiment in the first and second casings 11 and 12, respectively. The main feature is that the first and second refrigeration cycle units 13 and 14 are housed and configured.

  The heating system 1A deletes the water pump 8 interposed in the water pipe 3, while the first and second water branch pipes 3a and 3b of the first and second refrigeration cycle units 13 and 14 are removed. In the middle of each, instead of the first and second flow rate regulating valves 6, 7, first and second water pumps 15, 16 are interposed, respectively.

  Furthermore, the heating system 1A can attach and detach the inlet side and the outlet side of the first water branch pipe 3a of the first refrigeration cycle unit 13 and the outlet side and the inlet side of the water pipe 3 of the hot water storage tank 2 respectively. A pair of first joints 17a and 17b to be connected is provided. The first joints 17a and 17b are provided with on-off valves (not shown), and the pipes of the first water branch pipes 3a can be appropriately opened and closed.

  Similarly, a pair of second joints detachably connect the inlet side and outlet side of the water branch pipe 3 of the second refrigeration cycle unit 14 and the outlet side and inlet side of the water pipe 3 of the hot water storage tank 2 respectively. 18a and 18b are provided. These second joints 18a and 18b are also provided with open / close valves (not shown) so that the pipes of the second water branch pipes 3b can be appropriately opened and closed.

  Therefore, according to this heating system 1A, the effects of the first embodiment can be obtained, the number of combined first refrigeration cycle units 13 employing an HFC refrigerant containing unsaturated carbon, and unsaturated carbon are not included. The number of combinations of the second refrigeration cycle units 14 can be freely set, and an optimum system can be assembled according to the business condition in which the hot water supply system is introduced. For example, the number of first refrigeration cycle units 13 of HFC refrigerant containing unsaturated carbon is increased in places where there is a high temperature demand or in cold regions, and the second use of HFC refrigerant containing no unsaturated carbon is used in warming areas. It is possible to increase the number of refrigeration cycle units 14. The operation of each refrigeration cycle unit 13, 14 may be configured to be controllable by a central remote controller.

  In the above embodiment, the first and second water-refrigerant heat exchangers 4a and 5a are configured to exchange heat with hot water that passes through the water heat exchange pipe and refrigerant that flows through the refrigerant heat exchange pipe. However, the present invention is not limited to this. For example, one of water and refrigerant to be heat exchanged is used as the shell of the first and second water-refrigerant heat exchangers 4a and 5a. A shell and tube type may be used. Furthermore, a replenishment system for replenishing water from the outside to the hot water storage tank 2 may be provided.

  As described above, the heating system according to each embodiment can discharge hot water at a high temperature required on the use side, and also can ensure the required amount of hot water discharge even at the time of high temperature hot water discharge. , COP (coefficient of performance) can be increased, and high efficiency can be achieved.

  As mentioned above, although several embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1,1A ... Heating system, 2 ... Hot water storage tank (use side), 3 ... Water piping, 4 ... 1st freezing cycle, 4a ... 1st water-refrigerant heat exchanger, 5 ... 2nd freezing cycle, 5a ... 2nd water-refrigerant heat exchanger, 11 ... 1st housing | casing, 12 ... 2nd housing | casing, 13 ... 1st refrigeration cycle unit, 14 ... 2nd refrigeration cycle unit, 17a, 17b ... 1st joint, 18a, 18b ... 2nd joint.

Claims (4)

A first refrigeration cycle comprising a first water-refrigerant heat exchanger for exchanging heat between water and refrigerant and using an HFC refrigerant having unsaturated carbon as a refrigerant;
A second refrigeration cycle comprising a second water-refrigerant heat exchanger and a refrigerant selected from any one of an HFC refrigerant and a natural refrigerant having no unsaturated carbon as the refrigerant; and the first and second waters A water pipe for circulating water through the water heat exchange pipe of the refrigerant heat exchanger;
Connecting the first water-refrigerant heat exchanger and the second water-refrigerant heat exchanger in parallel to the water pipe;
Water is heated in each of the first water-refrigerant heat exchanger and the second water-refrigerant heat exchanger,
A heating system characterized in that the water sent from the first water-refrigerant heat exchanger and the second water-refrigerant heat exchanger are combined and supplied to the use side. 2. A heating system according to claim 1, further comprising hot water control means for controlling the temperature and flow rate of the hot water sent from the first and second water-refrigerant heat exchangers according to the required load. . The temperature and flow rate of hot water sent from the first and second water-refrigerant heat exchangers to the user side according to the temperature of water supplied to the first and second water-refrigerant heat exchangers, respectively. The heating system according to claim 1, further comprising a hot water control means for controlling. The first refrigeration cycle is accommodated in a first casing to constitute a first refrigeration cycle unit, and the second refrigeration cycle is accommodated in a second casing to constitute a second refrigeration cycle unit. The water pipes can be connected to the water heat exchange pipes of the first and second water-refrigerant heat exchangers of the first and second refrigeration cycle units, respectively. The heating system according to any one of the above.

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