JP2021134933A - Feedwater heating system - Google Patents

Abstract

To further improve efficiency in a feedwater heating system using both of a heat pump circuit and a heat exchanger for heat recovery.SOLUTION: A feedwater heating system 1 includes: a vapor compression-type heat pump circuit 10 in which a compressor 11, a condenser 12, an expansion valve 13 and an evaporator 14 are annularly connected by a refrigerant circulation line L9, and which takes out hot heat by the condenser 12 by driving the compressor 11; a heat recovery heat exchanger 40; a heat source fluid line L5 for circulating the heat source fluid successively to the heat recovery heat exchanger 40 and the evaporator 14; a water supply line L1 for circulating feedwater W1 successively to the heat recovery heat exchanger 40 and the condenser 12; refrigerant flow rate adjustment means controlled on the basis of a superheating degree of a gas refrigerant R flowing into the compressor 11, and adjusting a flow rate of the refrigerant; feedwater flow rate adjustment means controlled on the basis of a hot water tapping temperature of the feedwater W1 flowing out from the condenser 12 and adjusting a feedwater flow rate; and control means for controlling the refrigerant flow rate adjustment means and the feedwater flow rate adjustment means.SELECTED DRAWING: Figure 1

Description

The present invention relates to a water supply heating system.

In recent years, factories and other business establishments have been making efforts to utilize unused heat discarded in various facilities for the purpose of reducing the emission of carbon dioxide, which is a greenhouse gas. Therefore, as shown in Patent Document 1 and Patent Document 2, an unused heat utilization system (water supply heating system) that heats the boiler feed water by a heat pump circuit using waste hot water as a heat source and reduces the fuel consumption of the boiler. Has been proposed.

Japanese Unexamined Patent Publication No. 2013-210118 Japanese Unexamined Patent Publication No. 2014-169819

The water supply heating system described in Patent Documents 1 and 2 can be applied not only to the heating of boiler water supply but also to the heating of irrigation water in various production processes. In the system according to Patent Document 1, the heat source fluid (waste hot water) is circulated in the order of the evaporator and the heat recovery heat exchanger, and the water supply (cold water) is supplied in the order of the heat recovery heat exchanger, the supercooler and the condenser. It is a structure to be distributed. With this configuration, the system according to Patent Document 1 has succeeded in significantly increasing the COP (coefficient of performance: energy consumption efficiency) as compared with the conventional heat pump system without a heat exchanger for heat recovery and a supercooler. There is. On the other hand, this system has a problem that the heat exchanger for heat recovery becomes ineffective when the temperature of the heat source fluid becomes relatively low (for example, 40 ° C. or lower).
On the other hand, the system according to Patent Document 2 has a configuration in which a heat source fluid (waste hot water) is circulated in the order of a heat recovery heat exchanger and an evaporator. With this configuration, in the system according to Patent Document 2, if the temperature of the heat source fluid is higher than that of the water supply, the effectiveness of the heat recovery heat exchanger can be maximized. The system according to Patent Document 2 enables heat recovery at a high COP for heat source fluids in a wide temperature range, but is further applied to business establishments that have set high-level carbon dioxide emission reduction targets. High efficiency is desired.

The present invention has been made in view of the above problems, and an object of the present invention is to further improve the efficiency of a water supply heating system in which a heat pump circuit and a heat exchanger for heat recovery are used in combination.

The present invention comprises a steam compression type heat pump circuit in which a compressor, a condenser, an expansion valve and an evaporator are cyclically connected by a refrigerant circulation line, and heat is taken out by the condenser by driving the compressor, and heat for heat recovery. The exchanger, the heat source fluid line that circulates the heat source fluid in the order of the heat recovery heat exchanger and the evaporator, the water supply line that circulates the water supply in the order of the heat recovery heat exchanger and the condenser, and the compression. A refrigerant flow rate adjusting means that is controlled based on the degree of superheat of the gas refrigerant flowing into the machine to adjust the refrigerant flow rate, and a water supply flow rate adjustment that is controlled based on the hot water discharge temperature of the supply water flowing out from the compressor to adjust the water supply flow rate. The present invention relates to a water supply heating system including means, a refrigerant flow rate adjusting means, and a control means for controlling the water supply flow rate adjusting means.

Further, the heat source fluid line has a connection configuration in which the heat source fluid and the supply water are heat-exchanged by the counterflow in the heat recovery heat exchanger, and then the heat source fluid and the liquid refrigerant are heat-exchanged by the counterflow in the evaporator. Is preferable.

Further, a suction temperature sensor that detects the suction temperature of the gas refrigerant flowing into the compressor, a steam pressure sensor that detects the steam pressure of the gas refrigerant flowing out of the evaporator, and a hot water discharge temperature of the water supply flowing out of the condenser. The control means obtains the evaporation temperature of the liquid refrigerant from the detection pressure of the vapor pressure sensor, and subtracts the evaporation temperature from the detection temperature of the suction temperature sensor to detect the gas refrigerant. The degree of superheat is calculated, the refrigerant flow rate adjusting means is controlled so that the calculated degree of superheat becomes the target degree of superheat, and the water supply flow rate adjusting means is controlled so that the detected temperature of the hot water temperature sensor becomes the target hot water temperature. Is preferable.

Further, it is preferable that the heat source temperature sensor for detecting the temperature of the heat source fluid before flowing into the evaporator is provided, and the control means sets the target superheat degree according to the detection temperature of the heat source temperature sensor.

Further, when the control means determines that the fluctuation of the detection temperature of the heat source temperature sensor is large, it is preferable to increase the target degree of superheat.

Further, when the control means determines that the detection temperature of the heat source temperature sensor is stable, it is preferable to reduce the target degree of superheat.

Further, it is preferable that the water supply temperature sensor for detecting the temperature of the water supply water before flowing into the condenser is provided, and the control means sets the target hot water discharge temperature according to the detection temperature of the water supply temperature sensor.

Further, the water supply temperature sensor for detecting the temperature of the water supply water before flowing into the condenser is provided, the target hot water discharge temperature can be set to a value between the upper limit value and the lower limit value, and the lower limit value is the water supply. It is preferable that the value is obtained by adding a predetermined value to the detection temperature of the temperature sensor, and the higher the detection temperature of the water supply temperature sensor, the higher the value.

Also, one or two bypass lines that bypass the water supply to the heat recovery heat exchanger and / or bypass the heat source fluid to the heat recovery heat exchanger, and the water supply and heat source fluid. It is preferable to provide a preheating mode switching means for switching between a preheating mode for supplying water to be distributed to the heat recovery heat exchanger and a preheating stop mode for distributing at least one of the water supply and the heat source fluid to the bypass line at the same time.

Further, a heat exchanger pre-inflow water supply temperature sensor that detects the temperature of the water supply before flowing into the heat recovery heat exchanger and heat that detects the temperature of the heat source fluid before flowing into the heat recovery heat exchanger. The control means includes a heat source temperature sensor before inflow of the exchanger, and the control means determines the first detected temperature by the water supply temperature sensor before inflow of the heat exchanger and the second detected temperature by the heat source temperature sensor before inflow of the heat exchanger. By comparison, when the first detection temperature is lower than the second detection temperature, the preheating mode switching means is controlled so as to execute the water supply preheating mode, and the first detection temperature is the second detection temperature. If it exceeds, it is preferable to control the preheating mode switching means so as to execute the preheating stop mode.

Further, the control means has a signal input unit that receives a preheating mode designation signal that specifies the type of the water supply preheating mode or the preheating stop mode, and the water supply preheating according to the preheating mode designation signal input to the signal input unit. It is preferable to have a preheating mode switching control unit that controls the preheating mode switching means so as to execute the mode or the preheating stop mode.

According to the present invention, it is possible to further improve the efficiency of a water supply heating system in which a heat pump circuit and a heat exchanger for heat recovery are used in combination.

It is a figure which shows typically the water supply heating system which concerns on one Embodiment of this invention. It is a block diagram which shows the control part of the said embodiment. It is a graph which shows the fluctuation of the detection temperature of a heat source temperature sensor. It is a figure which shows the settable range of the target hot water temperature in the said embodiment. It is a Moriel diagram for explaining a heat pump cycle. It is a state transition diagram of the water flow mode switching control in the said embodiment. It is a flowchart which shows the flow of the setting process of the target superheat degree in the said embodiment. It is a flowchart which shows the flow of the preheating mode switching control in the said embodiment. It is a figure which shows typically the water supply heating system which concerns on the modification of the said embodiment.

Hereinafter, a preferred embodiment of the water supply heating system 1 of the present invention will be described with reference to the drawings. In addition, the "line" in this specification is a general term of a line capable of flowing a fluid such as a flow path, a path, and a pipeline.

FIG. 1 is a diagram schematically showing a configuration of a water supply heating system 1 according to the present embodiment. As shown in FIG. 1, the water supply heating system 1 is a system that supplies hot water W1 heated by the heat recovery heat exchanger 40 and the heat pump circuit 10 to hot water demand points as hot water W2.

More specifically, the water supply heating system 1 of the present embodiment includes a make-up water tank 70 for storing the make-up water W used as the water supply W1, a heat recovery heat exchanger 40 for heating the water supply W1, and a heat pump circuit. A hot water tank 60 for storing the heated supply water W1 as hot water W2, and a heat source water tank 50 for storing heat source water W5 as a heat source fluid are provided.
Further, in the water supply heating system 1 of the present embodiment, the water supply line L1 for circulating the water supply W1 in the order of the heat recovery heat exchanger 40 and the condenser 12 of the heat pump circuit 10 and the hot water W2 in the hot water tank 60 are heat-recovered. A recirculation line L2 that recirculates to the upstream side of the heat exchanger 40, a bypass line L3 that bypasses the water supply W1 to the heat recovery heat exchanger 40, and hot water W2 in the hot water tank 60 are supplied to hot water demand points. It is provided with a hot water supply line L4 for performing the heat recovery, and a heat source fluid line L5 for circulating the heat source water W5 as the heat source fluid through the heat exchanger 40 for heat recovery and the evaporator 14 of the heat pump circuit 10.

The make-up water tank 70 is a tank for storing the make-up water W used as the supply water W1 to be heated by the heat recovery heat exchanger 40 and the heat pump circuit 10, and the water supply line L1 is connected to the make-up water tank 70.

The heat recovery heat exchanger 40 is an indirect heat exchanger that performs indirect heat exchange between the water supply W1 flowing through the water supply line L1 and the heat source water W5 flowing through the heat source fluid line L5. More specifically, the heat recovery heat exchanger 40 heats between the water supply W1 before passing through the condenser 12 of the heat pump circuit 10 and the heat source water W5 before passing through the evaporator 14 of the heat pump circuit 10. Make a replacement.
The water supply W1 of the water supply line L1 passes through the heat recovery heat exchanger 40 and the condenser 12 in this order, and the heat source water W5 of the heat source fluid line L5 passes through the heat recovery heat exchanger 40 and the evaporator 14 in this order.

The heat pump circuit 10 is a steam compression type heat pump circuit in which a compressor 11, a condenser 12, an expansion valve 13, and an evaporator 14 are connected in an annular shape by a refrigerant circulation line L9, and heat is taken out by the condenser 12 by driving the compressor 11. Is. Refrigerant R flows through the refrigerant circulation line L9.
The compressor 11 has an electric motor 15 as a drive source, and compresses a gaseous refrigerant R such as chlorofluorocarbon gas into a high-temperature and high-pressure refrigerant R. The condenser 12 dissipates heat to the water supply W1 sent through the water supply line L1 to condense and liquefy the refrigerant R from the compressor 11. The expansion valve 13 reduces the pressure and temperature of the refrigerant R by passing the refrigerant R sent from the condenser 12. The evaporator 14 absorbs heat from the heat source water W5 sent through the heat source fluid line L5 to evaporate the refrigerant R sent from the expansion valve 13.
In this way, in the heat pump circuit 10, in the evaporator 14, the refrigerant R takes heat from the outside and vaporizes, while in the condenser 12, the refrigerant R dissipates heat to the outside and condenses. Utilizing such a principle, the heat pump circuit 10 draws heat from the heat source water W5 in the evaporator 14 and heats the water supply W1 in the water supply line L1 in the condenser 12.

In the refrigerant circulation line L9 of the heat pump circuit, a suction temperature sensor 17 that detects the suction temperature of the gas refrigerant R flowing into the compressor 11 and a steam pressure sensor 18 that detects the vapor pressure of the gas refrigerant R flowing out of the evaporator 14 And are provided.

Here, the expansion valve 13 constitutes a refrigerant flow rate adjusting means for adjusting the flow rate of the refrigerant R flowing through the refrigerant circulation line L9 of the heat pump circuit 10. Specifically, the expansion valve 13 is configured as a proportionally controlled needle valve, and the stroke of the needle valve is changed by controlling the rotation speed of the drive stepping motor to adjust the valve opening degree, thereby increasing the flow rate of the refrigerant R. Can be adjusted.

The hot water tank 60 is a tank that stores the supply water W1 heated by the heat recovery heat exchanger 40 and the heat pump circuit 10 as hot water W2.
The hot water W2 stored in the hot water tank 60 can be circulated and heated. Specifically, the hot water W2 in the hot water tank 60 merges with the water supply line L1 through the reflux line L2, and is heated again through the heat recovery heat exchanger 40 and the condenser 12 through the water supply line L1. , It is possible to return to the hot water tank 60.
The hot water tank 60 is provided with a hot water temperature sensor 61 that detects the temperature of the hot water W2 in the hot water tank 60. Further, the hot water tank 60 is provided with a water level detecting unit 62 for detecting the water level in the hot water tank 60. In the present embodiment, the water level detection unit 62 is composed of an electrode type water level detector including a plurality of electrode rods. Specifically, two electrode rods 621 and 622 having different lengths are inserted and held at different height positions of the lower end portions thereof. In the present embodiment, the electrode rods 621 and 622 are inserted into the hot water tank 60 with the height position of the lower end portion lowered in order. Each of the electrode rods 621 and 622 detects the presence or absence of a water level at the lower end portion depending on whether or not the lower end portion thereof is immersed in water.
In the present embodiment, the control unit 100 performs switching control of the water flow mode, which will be described later, by using the detection results of the hot water temperature sensor 61 and the water level detection unit 62. The details of this control will be described later.

The heat source water tank 50 stores the heat source water W5 as the heat source fluid of the heat pump circuit 10. As the heat source water W5, for example, waste hot water from a factory is used. The heat source water tank 50 is provided with an overflow line (not shown) that overflows a predetermined amount of heat source water. Further, the heat source water tank 50 is provided with a water level detection unit (not shown) for monitoring that the heat source water does not fall below a predetermined low water level.

The upstream side of the water supply line L1 is connected to the make-up water tank 70, and the downstream side thereof is connected to the hot water tank 60. Then, from the upstream side, the water supply line L1 includes a water supply pump 21, a first check valve 23, a first water supply temperature sensor 24, a three-way valve 25 arranged at a bypass line branch, and a heat recovery heat exchanger 40. The second water supply temperature sensor 26, the condenser 12, and the hot water temperature sensor 27 are sequentially arranged.

The rotation speed of the water supply pump 21 can be controlled by an inverter. By changing the rotation speed of the water supply pump 21, the flow rate of water supplied to the hot water tank 60 via the water supply line L1 can be adjusted in the case of the transient water flow mode described later. That is, the water supply pump 21 constitutes a water supply flow rate adjusting means in the transient water flow mode.
The first check valve 23 is provided on the upstream side of the confluence portion of the reflux line L2, which will be described later. This prevents the hot water W2 from flowing into the make-up water tank 70 side in the circulation water flow mode described later.
The first water supply temperature sensor 24 is a heat exchanger pre-inflow water supply temperature sensor that detects the temperature of the water supply W1 before it flows into the heat recovery heat exchanger 40. The first water supply temperature sensor 24 is provided on the upstream side of the branch portion of the bypass line L3.
The three-way valve 25 is arranged at a branch portion of the bypass line L3. The three-way valve 25 is a means for switching whether or not to bypass the water supply W1 to the heat recovery heat exchanger 40, and constitutes a preheating mode switching means. The bypass line L3 is a bypass line that bypasses the water supply W1 to the heat recovery heat exchanger 40.
The second water supply temperature sensor 26 is a water supply temperature sensor that detects the temperature of the water supply W1 before flowing into the condenser 12 of the heat pump circuit 10. The second water supply temperature sensor 26 is arranged on the upstream side of the condenser 12, and in the present embodiment, is arranged on the downstream side of the heat recovery heat exchanger 40.
The hot water temperature sensor 27 detects the hot water temperature of the heated water supply W1 flowing out of the condenser 12.

The upstream side of the reflux line L2 is connected to the hot water tank 60, and the downstream side thereof is connected to the water supply line L1. A recirculation pump 31 (circulation pump 31) and a second check valve 33 are sequentially arranged on the recirculation line L2 from the upstream side.

The rotation speed of the reflux pump 31 can be controlled by an inverter. By changing the rotation speed of the recirculation pump 31, it is possible to adjust the water supply flow rate that circulates so as to return to the hot water tank 60 via the recirculation line L2 and the water supply line L1 in the case of the circulation water flow mode described later. That is, the recirculation pump 31 constitutes a water supply flow rate adjusting means in the circulation water flow mode.
The second check valve 33 is provided in the recirculation line L2 on the upstream side of the confluence of the water supply line L1 and the recirculation line L2. This prevents the make-up water W from the make-up water tank 70 from flowing into the hot water tank 60 side in the transient water flow mode described later.

By providing such a water supply line L1 and a recirculation line L2, when the water supply pump 21 is operated with the recirculation pump 31 stopped, the replenishment water W from the replenishment water tank 70 is used as the replenishment water W1 for heat exchange for heat recovery. Water can be supplied to the hot water tank 60 while being heated through the vessel 40 and the condenser 12 in this order. This is called the transient water flow mode. On the other hand, when the reflux pump 31 is operated with the water supply pump 21 stopped, the hot water W2 in the hot water tank 60 is used as the water supply W1 and is passed through the heat recovery heat exchanger 40 and the condenser 12 in this order to reheat the hot water. It can be returned to the tank 60 to circulate the stored water in the hot water tank 60. This is called a circulating water flow mode. Further, when both the water supply pump 21 and the reflux pump 31 are stopped, the water flow to the heat recovery heat exchanger 40 and the condenser 12 can be stopped. This is called the water flow stop mode.

That is, in the present embodiment, the water supply pump 21 and the recirculation pump 31 distribute the hot water W2 to the recirculation line L2 and the transient water flow mode in which the hot water W2 is passed through the condenser 12 without being circulated to the recirculation line L2. It constitutes a water flow mode switching means for switching between a circulating water flow mode in which water is passed through the condenser 12 and a water flow stop mode in which water flow to the condenser 12 is stopped.

Then, the hot water W2 in the hot water tank 60 is supplied to the hot water demand point through the hot water supply line L4.
The hot water supply line L4 is provided with a hot water supply pump 63. An example of a hot water demand location is the use of steam boilers for water supply. However, the destination of the hot water W2 is not limited to the steam boiler. For example, hot water W2 produced by the water supply heating system 1 of the present embodiment may be used for cleaning containers for foods, beverages, and chemicals, sterilizing pastorizers (sterilizing bottles), and the like. In this case, the supply of hot water W2 in a high temperature range of about 60 ° C. to 80 ° C. may always be required. According to the water supply heating system 1 of the present embodiment, in such an application in which the supply of hot water having a temperature within a predetermined temperature range is always required, for example, only the water supply W1 heated in the hot water tank 60 is used. In a system in which hot water is supplied (a system in which unheated make-up water is not directly supplied to the hot water tank 60), hot water can be efficiently heated and supplied while maintaining the temperature. ..

In the heat source fluid line L5, a heat source supply pump 53, a first heat source temperature sensor 54, a heat recovery heat exchanger 40, a second heat source temperature sensor 55, and an evaporator 14 are sequentially arranged from the upstream side.
By operating the heat source supply pump 53, the heat source water W5 from the heat source water tank 50 can be circulated in the order of the heat recovery heat exchanger 40 and the evaporator 14.
The first heat source temperature sensor 54 is a heat source temperature sensor before inflow of the heat exchanger that detects the temperature of the heat source water W5 before flowing into the heat recovery heat exchanger. In the present embodiment, the first heat source temperature sensor 54 is provided in the heat source fluid line L5, but this sensor may be provided in the heat source water tank 50.
The second heat source temperature sensor 55 is a heat source temperature sensor that detects the temperature of the heat source fluid that exchanges heat with the refrigerant R in the evaporator 14. In the present embodiment, the temperature of the heat source water W5 before flowing into the evaporator 14 is detected. The second heat source temperature sensor 55 is arranged on the upstream side of the evaporator 14, and in the present embodiment, is arranged on the downstream side of the heat recovery heat exchanger 40.

As described above, the heat source fluid line L5 has a connection configuration in which the heat source water W5 is circulated in the order of the heat recovery heat exchanger 40 and the evaporator 14.
In this way, by flowing the heat source water W5 through the heat recovery heat exchanger 40 first, the amount of preheat of the water supply W1 can be increased, and the heat output of the heat recovery heat exchanger 40 can be increased. The higher the temperature of the heat source water W5, the greater the effect of increasing the heat output.

Further, in the heat source fluid line L5, as shown in FIG. 1, after heat exchange between the heat source water W5 and the supply water W1 by the heat recovery heat exchanger 40 by counterflow, the heat source water W5 and the liquid refrigerant R are exchanged by the evaporator 14. The connection configuration is such that heat is exchanged by the counter flow.
In this way, the heat source water W5 flows in the order of the heat recovery heat exchanger 40 and the evaporator 14, and the heat recovery heat exchanger 40 and the evaporator 14 each flow in a counterflow with respect to the flow direction of the water supply W1. Thereby, the heat recovery amount can be maximized.

Next, the control unit 100 of the water supply heating system 1 of the present embodiment will be described. FIG. 2 is a block diagram of a control unit 100 as a control means of the water supply heating system 1 of the present embodiment. The control unit 100 includes a target superheat degree setting unit 111, a superheat degree calculation unit 112, a refrigerant flow rate control unit 113, a target hot water temperature settable range determination unit 121, a target hot water temperature setting unit 122, and a water supply flow rate control unit. It includes 123, a water flow mode switching control unit 130, a preheating mode switching control unit 140, a signal input unit 150, and a storage unit 160.

The target superheat degree setting unit 111 acquires the temperature of the heat source water W5 as the heat source fluid detected by the second heat source temperature sensor 55 as the heat source temperature sensor, and the target superheat according to the detected temperature of the second heat source temperature sensor 55. Set the degree. For example, when the temperature of the heat source water W5 as the heat source fluid is low, the target superheat degree is set low. As a result, the circulating flow rate of the refrigerant R increases, and the amount of heat recovered can be increased even with the low-temperature heat source water W5.
In this way, by setting an appropriate target degree of superheat according to the temperature of the heat source water W5 as the heat source fluid, heat recovery in the evaporator 14 can be prevented while preventing damage to the compressor 11 due to liquid compression or poor lubrication. The amount can be increased.

Further, when the target superheat degree setting unit 111 determines that the fluctuation of the detection temperature of the second heat source temperature sensor 55 is large, the target superheat degree setting unit 111 may perform control to increase the target superheat degree.
FIG. 3 is a graph when the vertical axis is the detection temperature T of the second heat source temperature sensor 55 and the horizontal axis is the time t, and is a graph showing the fluctuation of the detection temperature of the second heat source temperature sensor 55. For example, as shown in FIG. 3, when the amount of change ΔT of the detection temperature T of the second heat source temperature sensor 55 per unit time t0 exceeds a predetermined threshold value ΔT0, the fluctuation of the detection temperature of the second heat source temperature sensor 55 changes. It is determined that it is large, and control is performed to increase the target degree of superheat. For example, ΔT0 = 5 ° C. and t0 = 1min, and control is performed to increase the target degree of superheat when there is a fluctuation larger than 5 ° C./min. At this time, for example, if the target superheat degree up to that point has been set to 5 ° C., the target superheat degree is set to, for example, 10 ° C. In the example of FIG. 3, the amount of decrease ΔT of the detection temperature T per unit time t0 is larger than the predetermined threshold value ΔT0. Therefore, since it is considered that the temperature of the heat source water W5 changes suddenly, the target superheat degree is changed to, for example, 10 ° C.

As a result, the heat pump circuit 10 can be stably driven even when a situation is confirmed in which the temperature of the heat source water W5 as the heat source fluid suddenly changes.
For example, even when the temperature of the heat source water W5 suddenly drops due to a sudden change, the refrigerant R can be reliably vaporized by the evaporator 14 by setting the target superheat degree to a high value. , It is possible to prevent damage to the compressor 11 due to liquid compression.

Further, when the target superheat degree setting unit 111 determines that the detection temperature of the second heat source temperature sensor 55 is stable, the target superheat degree setting unit 111 may perform control to reduce the target superheat degree.
For example, when the detection temperature T of the second heat source temperature sensor 55 is within a predetermined temperature range for a predetermined time, it is determined that the detection temperature of the second heat source temperature sensor 55 is stable. Further, when the detection temperature T is less than the predetermined threshold value ΔT0 for the predetermined time and the change amount ΔT per unit time t0, it may be determined that the detection temperature of the second heat source temperature sensor 55 is stable. At this time, control is performed to reduce the target degree of superheat. For example, when the target superheat degree up to that point has been set to 10 ° C., the target superheat degree is changed to, for example, 5 ° C.

By setting the lower limit of the target superheat degree to, for example, 5 ° C., damage to the compressor 11 due to liquid compression can be prevented. Further, by setting the upper limit value of the target superheat degree to, for example, 10 ° C., the circulating flow rate of the refrigerant R can be maintained at a predetermined flow rate or higher, and a decrease in the heat recovery amount can be prevented.

In this way, when the temperature of the heat source water W5 as the heat source fluid is stable, the circulating flow rate of the refrigerant R is increased by setting the target superheat degree to a low value, and the amount of heat recovered by the evaporator 14 is increased. Can be increased.

In the present embodiment, the detection temperature of the second heat source temperature sensor 55 is used as the heat source temperature sensor to set the target superheat degree, but the temperature of the heat source water W5 before flowing into the evaporator 14 ( The first heat source temperature sensor 54 may be used as the heat source temperature sensor for detecting the heat source temperature before the inflow of the evaporator. Although not immediately before flowing into the evaporator 14, the first heat source temperature sensor 54 can also indirectly detect the temperature of the heat source fluid that exchanges heat with the refrigerant R in the evaporator 14, and is a heat source. It is possible to confirm the situation where the temperature of the water W5 changes suddenly. However, it is more preferable to use the second heat source temperature sensor 55 to measure the temperature of the heat source water W5 immediately before flowing into the evaporator 14.

The superheat degree calculation unit 112 calculates the superheat degree of the refrigerant R flowing into the compressor 11.
Specifically, the superheat degree calculation unit 112 obtains the evaporation temperature of the liquid refrigerant R from the detection pressure of the steam pressure sensor 18, and subtracts the evaporation temperature from the detection temperature of the suction temperature sensor 17 to obtain the superheat degree of the gas refrigerant R. calculate.

The refrigerant flow control unit 113 controls the refrigerant flow control means so that the calculated superheat degree (value calculated by the superheat degree calculation unit 112) becomes the target superheat degree (set value by the target superheat degree setting unit 111), and the refrigerant R Adjust the flow rate.
As a specific control, for example, the calculated superheat degree calculated in real time by the superheat degree calculation unit 112 is used as a feedback value, and the valve opening degree of the expansion valve 13 is adjusted so that the calculated superheat degree converges to the target superheat degree. It is preferable to adopt feedback control. As the feedback control, in addition to the proportional control (P control), an operation amount calculation algorithm that combines the integral control (I control) and / or the differential control (D control) can be adopted.

In this way, the superheat degree calculation unit 112 accurately calculates the superheat degree of the gas refrigerant R, and the refrigerant flow rate control unit 113 controls so as to keep the value constant, whereby the heat of the condenser 12 with respect to the water supply W1 is generated. The output is stable. As a result, the fluctuation of the flow rate of the supply water W1 that is heated and supplied as hot water is reduced.

The target hot water temperature settable range determination unit 121 acquires the temperature of the water supply W1 before flowing into the condenser 12 detected by the second water supply temperature sensor 26 as the water supply temperature sensor, and detects the second water supply temperature sensor 26. Determine the settable range of the target hot water temperature according to the temperature.

FIG. 4 is a diagram showing a settable range of the target hot water temperature, which is determined according to the detection temperature of the second water supply temperature sensor 26. The horizontal axis of FIG. 4 is the detection temperature of the second water supply temperature sensor 26 (water supply temperature before the inflow of the condenser), and the vertical axis is the corresponding target hot water discharge temperature.
The settable range of the target hot water temperature in the present embodiment is a triangular region shown in the settable range A. That is, in the present embodiment, the target hot water temperature can be set to a value between the upper limit value and the lower limit value, and the lower limit value is a value obtained by adding a predetermined value to the detection temperature of the second water supply temperature sensor 26. Therefore, the higher the detection temperature of the second water supply temperature sensor 26, the higher the value. More specifically, the lower limit value is a value obtained by adding 15 ° C. to the detection temperature of the second water supply temperature sensor 26, and the upper limit value is a constant temperature, 75 ° C. in the present embodiment.

A predetermined value (for example, 15 ° C.) for setting the lower limit value is stored in the storage unit 160 described later. In this case, it is preferable that this predetermined value can be set by an external input or the like. Alternatively, the lower limit value based on this predetermined value may be stored in the storage unit 160.

In this way, by setting the area shown in the settable range A as the settable range of the target hot water temperature, the system is set so that the temperature difference between the water supply W1 on the inlet side and the outlet side of the condenser 12 becomes sufficiently large. Since the control is performed, it is possible to prevent insufficient supercooling of the refrigerant R flowing through the heat pump circuit 10, and it is possible to suppress an excessive supply flow rate of the water supply W1 in the control of the water supply flow rate adjusting means by the water supply flow rate control unit 123 described later. can.

Even when the settable range of the target hot water temperature is a quadrangular region in which both the upper limit value and the lower limit value are constant values, that is, even when the lower limit value is constant, for example, FIG. If the region is as shown in the settable range B shown in the above, it is possible to prevent insufficient supercooling of the refrigerant R and suppress an excessive flow rate of the water supply W1. However, in this case, the allowable range of the heat source water temperature and the settable range of the target hot water temperature are narrowed.

When the target hot water temperature is set to a temperature lower than the lower limit value shown in the settable range A, for example, when it is not so different from the detection temperature of the second water supply temperature sensor 26, the refrigerant R is insufficiently supercooled. there is a possibility.

This will be described with reference to the Moriel diagram (ph diagram) shown in FIG.
The vertical axis of the Moriel diagram is the pressure (p) of the refrigerant, and the horizontal axis is the specific enthalpy (h) of the refrigerant. Then, the saturated liquid line Y1 and the saturated vapor line Y2 are shown in the Moriel diagram. Such a Moriel diagram can represent the state change of the refrigerant R during the heat pump cycle. The refrigerant R is in a supercooled liquid state (state of liquid refrigerant R) on the left side of the saturated liquid line Y1, a wet steam state in which a gas-liquid mixture is formed between the saturated liquid line Y1 and the saturated steam line Y2, and a saturated steam line. The superheated steam state (the state of the gas refrigerant R) is set on the right side of Y2.

The solid line indicated by R (a → b → c → d) in FIG. 5 indicates the transition of the state of the refrigerant R in the heat pump cycle in the proper state.
The superheated vapor state gas refrigerant R sucked into the compressor 11 is adiabatic compressed in the compressor 11 to become a high temperature and high pressure superheated steam state gas refrigerant R (a → b), and then condensed and excessively condensed by the condenser 12. By being cooled, it becomes a liquid refrigerant R in a supercooled liquid state (b → c), and after that, it becomes a refrigerant R in a wet steam state by being adiabatically expanded by the expansion valve 13 (c → d). Then, the refrigerant R in the wet steam state is evaporated and heated in the evaporator 14 to become the gas refrigerant R in the superheated steam state (d → a). In such a cycle, the refrigerant R circulates. Explaining the process of (b → c) in FIG. 5 in detail, the condenser 12 releases the latent heat and the sensible heat of the gas refrigerant R to change the gas refrigerant R into the liquid refrigerant R, and The liquid refrigerant R is overcooled.

Here, when the target hot water temperature is set to a temperature lower than the lower limit value shown in the settable range A, the temperature difference between the water supply W1 on the inlet side and the outlet side of the condenser 12 becomes small, so that the refrigerant R is the condenser. There is a possibility that the temperature of 12 will not be sufficiently condensed and supercooled (b → c'). As a result, the position of "c'" indicating the state of the refrigerant R after passing through the condenser 12 shifts to the right side as compared with the proper case. That is, the refrigerant R in the "c'" state is insufficiently supercooled. It is also possible that the liquid refrigerant R is not sufficiently in the state. In this case, it cannot be said that the operation can be performed with an appropriate heat pump cycle.
However, in the present embodiment, since the lower limit value is a value obtained by adding a predetermined value to the detection temperature of the second water supply temperature sensor 26, the temperature difference between the water supply W1 on the inlet side and the outlet side of the condenser 12 is at least. The system is controlled so as to be larger than a predetermined value, and the above-mentioned problem does not occur. That is, it can be operated with a heat pump cycle in an appropriate state.

The target hot water temperature setting unit 122 sets the target hot water temperature within the above-mentioned target hot water temperature settable range according to the detection temperature of the second water supply temperature sensor 26. For example, within the above-mentioned settable range A, an arbitrary target hot water temperature can be set based on the request of the hot water demand location and the like.
That is, the target hot water temperature setting unit 122 acquires the detection temperature of the second water supply temperature sensor 26, and is a value obtained by adding a predetermined value to the detected temperature of the acquired second water supply temperature sensor 26, and is the second water supply. The higher the detection temperature of the temperature sensor 26, the higher the lower limit value, and the target hot water temperature can be set. As a result, it is possible to operate with a heat pump cycle in an appropriate state, and it is possible to widen the setting range of the target hot water temperature.

In addition, a value obtained by adding a predetermined value to the detection temperature of the second water supply temperature sensor 26 may be automatically set as the target hot water discharge temperature.

The water supply flow rate control unit 123 controls the water supply flow rate adjusting means so that the detection temperature of the hot water temperature sensor 27 becomes the target hot water temperature (set value set by the target hot water temperature setting unit 122), and adjusts the flow rate of the water supply W1.
As specific control, for example, the drive frequency of the water supply pump 21 or the recirculation pump 31 is adjusted so that the hot water temperature detected in real time by the hot water temperature sensor 27 is used as a feedback value and the hot water temperature converges to the target hot water temperature. It is preferable to adopt feedback control. As the feedback control, in addition to the proportional control (P control), an operation amount calculation algorithm that combines the integral control (I control) and / or the differential control (D control) can be adopted.

In the transient water flow mode described later, the water supply pump 21 capable of inverter control constitutes the water supply flow rate adjusting means, and in the circulating water flow mode, the reflux pump 31 capable of inverter control constitutes the water supply flow rate adjusting means. To configure.

The water supply flow rate adjusting means may be configured by another aspect. For example, when the water supply pump 21 and the recirculation pump 31 are composed of pumps capable of only on / off control, a flow rate adjusting valve capable of proportional control may be provided on the downstream side of each pump, and these may be used as the water supply flow rate adjusting means. Further, a flow rate adjusting valve capable of proportional control may be provided on the downstream side of the confluence of the water supply line L1 and the reflux line L2, and this may be used as the water supply flow rate adjusting means.
Further, as a configuration to replace the water supply pump 21 and the recirculation pump 31, an on-off valve is provided in the water supply line L1 and the recirculation line L2, or a three-way valve is provided at the confluence of the water supply line L1 and the recirculation line L2. A pump capable of inverter control may be provided on the downstream side of the confluence of the water supply line L1 and the reflux line L2, and this may be used as the water supply flow rate adjusting means.

In this way, by setting an appropriate target hot water temperature according to the temperature of the water supply W1 before flowing into the condenser 12, it is possible to prevent the occurrence of insufficient supercooling, excessive water supply flow rate, etc. in the condenser 12. can.
Further, by setting the lower limit value of the range of the target hot water temperature that can be set according to the temperature of the water supply W1 before flowing into the condenser 12, it is possible to surely prevent the supercooling shortage in the condenser 12 and evaporate. The amount of heat recovered in the vessel 14 can be stabilized. Further, it is possible to prevent the flow rate of the water supply W1 from becoming excessive and suppress deterioration due to an overload of the water supply pump 21 or the like.

In this embodiment, the detection temperature of the second water supply temperature sensor 26 is used to set the target hot water temperature, but the temperature of the water supply W1 before flowing into the condenser 12 (water supply before the condenser inflow). The first water supply temperature sensor 24 may be used as the water supply temperature sensor that indirectly detects the temperature). However, in order to perform more stable control, it is preferable to use the second water supply temperature sensor 26 to measure the temperature of the water supply W1 immediately before flowing into the condenser 12.

As described above, in the water supply heating system 1 of the present embodiment, the heat source water W5 is circulated in the order of the heat recovery heat exchanger 40 and the evaporator 14. The water supply heating system 1 of the present embodiment includes a refrigerant flow rate adjusting means that is controlled based on the degree of superheat of the gas refrigerant R flowing into the compressor 11 and adjusts the refrigerant flow rate. Further, the water supply flow rate adjusting means which is controlled based on the hot water temperature of the water supply W1 flowing out from the condenser 12 and adjusts the water supply flow rate is provided. The control unit 100 includes a refrigerant flow rate control unit 113 that controls the refrigerant flow rate adjusting means, and a water supply flow rate control unit 123 that controls the water supply flow rate adjusting means.

As a result, the heat source water W5 is first flowed through the heat recovery heat exchanger 40, so that the heat output of the heat recovery heat exchanger 40 is increased and the preheat amount of the water supply W1 is increased. The higher the heat source water temperature, the greater the effect of increasing the heat output. When the heat recovery amount of the heat recovery heat exchanger 40 increases, the heat recovery amount of the heat pump circuit 10 can be relatively reduced. That is, when the same system heat output as when the heat source water W5 is passed in the order of the evaporator 14 and the heat recovery heat exchanger 40 is obtained, the output of the compressor can be reduced to reduce the power consumption of the heat pump circuit 10. can.
At this time, by first flowing the heat source water W5 through the heat recovery heat exchanger 40, the temperature of the heat source water W5 flowing into the evaporator 14 decreases, but further control is added, that is, the flow rate of the refrigerant based on the degree of superheat. Due to the multiple effect of the combination of adjustment and adjustment of the water supply flow rate based on the hot water temperature, for example, the heat input of the evaporator 14 is increased by adjusting the refrigerant flow rate according to the low superheat degree setting, and the water supply flow rate according to the low hot water temperature setting. Due to the multiple effects of further increasing the heat output of the heat recovery heat exchanger 40 and increasing the heat output of the evaporator 14, the heat source water W5 is first flowed to the heat recovery heat exchanger 40 by adjusting the COP of the system. Can be greatly increased.

The water flow mode switching control unit 130 performs water flow mode switching control for switching between a transient water flow mode, a circulation water flow mode, and a water flow stop mode. More specifically, the water flow mode switching control unit 130 controls the water supply pump 21 and the recirculation pump 31 as the water flow mode switching means, and allows water to flow to the condenser 12 without circulating the hot water W2 to the recirculation line L2. Control to switch between the transient water flow mode, the circulating water flow mode in which hot water W2 is circulated through the reflux line L2 and the water is passed through the condenser 12, and the water flow stop mode in which the water flow to the condenser 12 is stopped. conduct.

In the transient water flow mode, the recirculation pump 31 is stopped while the water supply pump 21 is driven, and the heat source supply pump 53 and the compressor 11 of the heat pump circuit 10 are driven. In the circulation water flow mode, the drive of the water supply pump 21 is stopped, the reflux pump 31 is driven, and the heat source supply pump 53 and the compressor 11 of the heat pump circuit 10 are driven. In the water flow stop mode, the drive of the water supply pump 21 and the recirculation pump 31 is stopped, and the drive of the compressor 11 of the heat pump circuit 10 is also stopped. It is also preferable to stop the drive of the heat source supply pump 53.

In the present embodiment, the water supply pump 21 and the recirculation pump 31 constitute the water flow mode switching means, but the water flow mode switching means may be configured by another aspect. For example, a three-way valve provided at the confluence of the water supply line L1 and the recirculation line L2 and a water supply pump provided at the downstream side of the confluence of the water supply line L1 and the recirculation line L2 constitute a water flow mode switching means. You can also do it. In this case, the water flow mode is switched by switching the three-way valve and turning the water supply pump on and off.

In this way, by enabling the operation in the circulating water flow mode in addition to the transient water flow mode, the hot water tank 60 can be circulated and heated to maintain the hot water storage temperature as needed. Further, in the circulation water flow mode, the recirculation line L2 is used to allow the stored water in the hot water tank 60 to flow in front of the heat recovery heat exchanger 40, so that the temperature of the heat source water W5 is stored in the hot water tank 60. When the temperature of the hot water W2 is higher than the temperature of the hot water W2, the hot water W2 flowing as the water supply W1 is heated not only by the condenser 12 but also by the heat recovery heat exchanger 40 before that. Therefore, it is heated efficiently.

Here, the water flow mode switching control unit 130 can control the water supply to the hot water tank 60 and also perform the water flow mode switching control based on the temperature of the hot water W2 in the hot water tank 60.
Specifically, the water flow mode switching control unit 130 is a water flow mode switching means so as to execute the transient water flow mode when a new water supply is executed to the confluence point of the recirculation line L2. When the new water supply to the confluence is stopped and the detection temperature of the hot water temperature sensor 61 is lower than the predetermined set temperature, the water flow mode switching means is executed so as to execute the circulation water flow mode. When the new water supply to the confluence is stopped and the detection temperature of the hot water temperature sensor 61 exceeds the predetermined set temperature, the water flow mode switching means is executed so as to execute the water flow stop mode. To control.

This water flow mode switching control will be described in detail with reference to the state transition diagram shown in FIG. 6A.
The water flow mode switching control unit 130 monitors the water level of the hot water W2 in the hot water tank 60 by the water level detection unit 62 while executing each water flow mode, and the temperature of the hot water W2 in the hot water tank 60 by the hot water temperature sensor 61. To monitor. During the execution of the water flow stop mode, the detection position of the electrode rod 622 of the water level detection unit 62 is exceeded, and the detection temperature of the hot water temperature sensor 61 is lower than the first set temperature (for example, 2 to 3 ° C. than the target hot water discharge temperature). When the temperature exceeds the temperature), the water flow mode switching control unit 130 continues the water flow stop mode.

<Event E1>
When the water level in the hot water tank 60 drops and falls below the detection position of the electrode rod 622 of the water level detection unit 62 during the execution of the water flow stop mode, the water flow mode switching control unit 130 stops the reflux pump 31. The water supply pump 21 is driven while maintaining the above. By driving the water supply pump 21, new make-up water W is supplied to the confluence of the reflux line L2. Therefore, the water flow mode switching control unit 130 connects the heat source supply pump 53 and the compressor 11. Drive to shift to transient water flow mode. In the one-pass water flow mode, hot water W2 adjusted to a predetermined target hot water temperature is supplied to the hot water tank 60.

<Event E2>
When the water level in the hot water tank 60 rises and exceeds the detection position of the electrode rod 621 of the water level detection unit 62 during the execution of the one-pass water flow mode, the water flow mode switching control unit 130 of the recirculation pump 31 The water supply pump 21 is stopped while maintaining the stop. When the water supply pump 21 is stopped, the supply of new make-up water W to the confluence of the reflux line L2 is stopped. Therefore, the water flow mode switching control unit 130 sets the heat source supply pump 53 and the compressor 11 to the compressor 11. Stop and shift to the water flow stop mode. In the water flow stop mode, the supply of hot water W2 to the hot water tank 60 is stopped.

<Event E3>
If the detection temperature of the hot water temperature sensor 61 falls below the set temperature during the execution of the water flow stop mode, the reflux pump 31 is driven while maintaining the stop of the water supply pump 21. By driving the recirculation pump 31, the water circulation of the stored water is executed in a state where the supply of the new make-up water W is stopped at the confluence of the recirculation line L2. , The heat source supply pump 53 and the compressor 11 are driven to shift to the circulation water flow mode. In the circulating water flow mode, the hot water W2 reheated to a predetermined target hot water temperature is supplied to the hot water tank 60.

<Event E4>
If the detected temperature of the hot water temperature sensor 61 exceeds the set temperature during the execution of the circulating water flow mode, the water flow mode switching control unit 130 stops the recirculation pump 31 while maintaining the stop of the water supply pump 21. Then, the heat source supply pump 53 and the compressor 11 are stopped to shift to the water flow stop mode. In the water flow stop mode, the circulation of the hot water W2 to the hot water tank 60 is stopped.

<Event E5>
When the water level in the hot water tank 60 drops and falls below the detection position of the electrode rod 622 of the water level detection unit 62 during the execution of the circulation water flow mode, the water flow mode switching control unit 130 stops the reflux pump 31. And drive the water supply pump 21. By driving the water supply pump 21, new make-up water W is supplied to the confluence of the reflux line L2. Therefore, the water flow mode switching control unit 130 connects the heat source supply pump 53 and the compressor 11. Shift to the transient water flow mode while driving. In the one-pass water flow mode, hot water W2 adjusted to a predetermined target hot water temperature is supplied to the hot water tank 60.
In this embodiment, the transition from the transient water flow mode to the circulating water flow mode is not performed. This is to give priority to the supply of the make-up water W to the hot water tank 60 and to quickly recover the water level because the mode shifts to the one-pass water flow mode when the demand for hot water is large. Further, since the hot water outlet temperature in the transient water flow mode is higher than the hot water storage temperature of the hot water tank 60, the hot water storage temperature can be raised in a short time.

The set temperature for determining the continuation of the water flow stop mode and the set temperature for determining the transition from the water flow stop mode to the circulating water flow mode may be the same temperature or different temperatures. .. If the temperatures are different, the latter set temperature is lower than the former set temperature.

In addition, in performing the above-mentioned switching control of the water flow mode, it is determined whether or not a new water supply by the make-up water W or the like is executed at the confluence of the return line L2 in the driving state (driving) of the water supply pump 21. It may be performed based on a command signal or a drive feedback signal).
Further, a flow rate sensor (not shown) may be arranged on the upstream side of the confluence of the return line L2 in the water supply line L1 and a determination may be made based on the detection result of the flow rate sensor.

According to the mode switching control according to the state transition diagram of FIG. 6A, when the demand for hot water is sufficient and the supply of make-up water W is required, the system can be operated in the transient water flow mode in which the system COP is maximized. can. Further, when the demand for hot water is small and the supply of the make-up water W is not necessary, the temperature of the stored water can be raised in the circulating water flow mode when the temperature of the stored water in the hot water tank 60 drops. Further, when the demand for hot water is small and the supply of the make-up water W is not necessary, if the temperature of the stored water in the hot water tank 60 does not substantially decrease, it is possible to stand by in the water flow stop mode.

With the configuration described above, hot water W2 having a set temperature or higher can always be secured in the hot water tank 60. Further, since the circulation water flow mode is executed only when the temperature of the stored water in the hot water tank 60 drops, wasteful power consumption is not generated due to excessive water circulation.

The preheating mode switching control unit 140 performs preheating mode switching control for switching between the water supply preheating mode and the preheating stop mode. More specifically, the preheating mode switching control unit 140 controls the three-way valve 25 as the preheating mode switching means, and simultaneously distributes the water supply W1 and the heat source water W5 to the heat recovery heat exchanger 40, and the water supply preheating mode and the water supply. Control is performed to switch between the preheating stop mode in which W1 is distributed to the bypass line L3.

In the present embodiment, the three-way valve 25 constitutes the preheating mode switching means, but the preheating mode switching means may be configured by another aspect. For example, two-way valves may be provided on the upstream side of the confluence with the bypass line L3 and the bypass line L3 in the water supply line L1, and the preheating mode switching means may be configured by these two-way valves.

The bypass line is not limited to the one that bypasses the water supply W1 to the heat recovery heat exchanger 40, and may be the one that bypasses the heat source water W5 to the heat recovery heat exchanger 40. In this case, the heat source water W5 is circulated to the bypass line in the preheating stop mode.
That is, the preheating mode is provided with one or two bypass lines for bypassing the water supply W1 to the heat recovery heat exchanger 40 and / or bypassing the heat source water W5 for the heat recovery heat exchanger 40. A mode in which the switching means switches between a water supply preheating mode in which the water supply W1 and the heat source water W5 are simultaneously circulated to the heat recovery heat exchanger 40 and a preheating stop mode in which at least one of the water supply W1 and the heat source water W5 is circulated in the bypass line. It should be.
As a result, the heat recovery heat exchanger 40 can be selectively used depending on the situation.

Here, the preheating mode switching control unit 140 is the first by the first water supply temperature sensor 24 (heat exchanger pre-inflow water supply temperature sensor 24) that detects the temperature of the water supply W1 before flowing into the heat recovery heat exchanger 40. First heat source temperature sensor 54 (heat source temperature sensor 54 before inflow of heat exchanger) that detects the detected temperature (water supply temperature before inflow of heat exchanger) and the temperature of heat source water W5 before flowing into the heat recovery heat exchanger 40. It is possible to acquire the second detection temperature (heat source temperature before the inflow of the heat exchanger) and the preheating mode switching control based on the first detection temperature and the second detection temperature.
Specifically, the preheating mode switching control unit 140 compares the first detected temperature by the first water supply temperature sensor 24 with the second detected temperature by the first heat source temperature sensor 54, and the first detected temperature is the second. When the temperature is lower than the detected temperature, the preheating mode switching means is controlled so as to execute the water supply preheating mode, and when the first detected temperature is higher than the second detected temperature, the preheating stop mode is executed. Controls the preheating mode switching means.
The system COP can be maximized by such automatic preheating mode switching according to the water supply temperature and the heat source water temperature.

The preheating mode switching control unit 140 can switch the preheating mode switching means between the preheating modes at least when the water flow mode is the circulating water flow mode. In this case, the preheating mode switching control unit 140 sets the preheating mode switching means to the preheating mode when the water flow mode is the transient water flow mode, and preheats and stops the preheating mode switching means when the water flow stop mode. It may be set to the mode.
As a result, for example, in the transient water flow mode in which the make-up water W, which often has a relatively low temperature as the water supply W1, is used, the heat exchanger for heat recovery is actively utilized, while the temperature is relatively high as the water supply W1. In the circulating water flow mode using the stored water of the hot water tank 60, which is often the case, the heat recovery heat exchanger can be selectively used according to the temperature relationship between the water supply W1 and the heat source water W5.
However, in order to enable efficient heating even under various make-up water temperatures and heat source water temperatures, the preheating mode switching control unit 140 is used when the water flow mode is the circulation water flow mode or the transient water flow mode. , The preheating mode switching means may be configured to be switchable between the preheating modes.

The signal input unit 150 includes a first signal input unit 151 that receives a water flow mode designation signal that specifies any of a transient water flow mode, a circulation water flow mode, and a water flow stop mode.
The water flow mode switching control unit 130 switches the water flow mode so as to execute the transient water flow mode, the circulating water flow mode, or the water flow stop mode according to the water flow mode designation signal input to the first signal input unit 151. Control the means. Then, the water flow mode switching control unit 130 stops the new water supply to the confluence portion of the recirculation line L2 by controlling the water supply pump 21 or the like when the circulation water flow mode or the water flow stop mode is executed.
Thereby, for example, it is possible to operate in the transient water flow mode in which the system COP is maximized by using an external signal with make-up water. In addition, it is possible to keep the stored water warm in the circulating water flow mode by using an external signal without make-up water.

The signal input unit 150 also includes a second signal input unit 152 that receives a preheating mode designation signal that specifies either a water supply preheating mode or a preheating stop mode.
The preheating mode switching control unit 140 controls the preheating mode switching means so as to execute the water supply preheating mode or the preheating stop mode according to the preheating mode designation signal input to the second signal input unit 152.
As a result, the system COP can be maximized by switching the passive preheating mode according to the external signal.

The storage unit 160 stores various information necessary for control, such as various threshold values.

Next, an example of the flow of control by the control unit 100 of the present embodiment will be described.

FIG. 6B is a flowchart showing an example of the flow of the target superheat degree setting process by the target superheat degree setting unit 111 of the control unit 100.

First, when the system is started, the target superheat degree setting unit 111 sets the target superheat degree to a higher temperature, for example, 10 ° C. in step S1.

Next, in step S2, it is determined whether or not the detection temperature of the second heat source temperature sensor 55 is stable and equal to or less than a predetermined heat source temperature threshold value (for example, 60 ° C.). When it is determined that the detection temperature of the second heat source temperature sensor 55 is stable (ΔT ≦ ΔT 0, see FIG. 3) and is equal to or less than the predetermined heat source temperature threshold value (step S2: YES), the target in step S3. Set the degree of superheat to a small value, for example 5 ° C. On the other hand, if it is determined that the detection temperature of the second heat source temperature sensor 55 is not stable, or if it is determined that the predetermined heat source temperature threshold is exceeded (step S2: NO), the process returns to step S1 and the target overheating is continued. Maintain the degree at 10 ° C.

After setting the target superheat degree to 5 ° C. in step S3, in step S4, it is determined whether or not the fluctuation of the detected temperature of the second heat source temperature sensor 55 is large, or whether or not the predetermined heat source temperature threshold value is exceeded. If it is determined that the fluctuation of the detected temperature of the second heat source temperature sensor 55 is large (ΔT> ΔT0, see FIG. 3), or if it is determined that the predetermined heat source temperature threshold is exceeded (step S4: YES), step S5. In, the target degree of superheat is increased and set to, for example, 10 ° C. On the other hand, if it is determined that the fluctuation of the detection temperature of the second heat source temperature sensor 55 is not large and is equal to or less than the predetermined heat source temperature threshold value (step S4: NO), the process returns to step S3 and the target superheat degree is continuously set to 5 ° C. Maintain to.
As a result, the heat pump circuit 10 can be stably driven even when a situation is confirmed in which the temperature of the heat source water W5 as the heat source fluid suddenly changes.

Next, the preheating mode switching control will be described. The water flow mode switching control is as described above (see FIG. 6A).
FIG. 6C is a flowchart showing an example of a flow of preheating mode switching control for switching between the water supply preheating mode and the preheating stop mode by the preheating mode switching control unit 140 of the control unit 100. In this example, the preheating mode switching control unit 140 has the first detection temperature (heat exchanger pre-inflow water supply temperature) by the first water supply temperature sensor 24 (heat exchanger pre-inflow water supply temperature sensor) and the first heat source temperature sensor 54. The preheating mode switching control is performed based on the detection result of the second detection temperature (heat source temperature before inflow of the heat exchanger) by the (heat source temperature sensor before inflow of the heat exchanger).

In step S11, the preheating mode switching control unit 140 determines whether or not the circulating water flow mode is being executed. When the circulating water flow mode is executed (step S21: YES), in step S12, the detection results of the first detected temperature by the first water supply temperature sensor 24 and the second detected temperature by the first heat source temperature sensor 54 are obtained. compare. Then, when the first detection temperature is lower than the second detection temperature (step S12: YES), the water supply preheating mode is executed in step S13. On the other hand, when the first detection temperature is not lower than the second detection temperature (step S12: NO), the preheating stop mode is executed in step S14.

In step S11, it is determined whether or not the transient water flow mode or the circulating water flow mode is executed, and if the transient water flow mode or the circulating water flow mode is executed, the process proceeds to step S12. Control may be adopted.

FIG. 7 is a diagram schematically showing a modified example of the water supply heating system 1 of the first embodiment.
The condenser 12 of the heat pump circuit 10 in the present embodiment has a function of condensing and supercooling the refrigerant R. However, as shown in this modification, the condenser of the heat pump circuit 10 mainly includes a condenser 12A that has a function of condensing the refrigerant R and a supercooler 12B that mainly has a function of supercooling the refrigerant R. It may be separated. In this case, the refrigerant R of the heat pump circuit 10 preferably releases latent heat in the condenser 12A and sensible heat in the supercooler 12B. That is, in the condenser 12A, the gas refrigerant R is condensed to become the liquid refrigerant R, the liquid refrigerant R is supplied to the supercooler 12B, and the liquid refrigerant R is further cooled (supercooled) in the supercooler 12B. NS.
The supercooler 12B is an indirect heat exchanger that exchanges heat between the water supply W1 sent to the condenser 12A and the refrigerant R flowing from the condenser 12A to the expansion valve 13. The supercooler 12B can supercool the refrigerant R from the condenser 12A to the expansion valve 13 by using the water supply W1 to the condenser 12A, and also use the refrigerant R from the condenser 12A to the expansion valve 13. The water supply W1 to the condenser 12A can be heated.
By separating the heat exchangers for condensing and supercooling the refrigerant R in this way, the design of the heat exchanger can be facilitated and the cost can be reduced. In addition, a general-purpose heat exchanger can be used.
In this modification, the second water supply temperature sensor 26 as a water supply temperature sensor that detects the temperature of the water supply W1 before flowing into the condenser 12 of the heat pump circuit 10 is arranged on the upstream side of the supercooler 12B. Is preferable.

If the temperature of the hot water W2 in the hot water tank 60 is allowed to decrease to some extent, such as when the hot water demand point is a steam boiler, the make-up water tank does not go through the heat recovery heat exchanger 40 and the heat pump circuit 10. A make-up water line (not shown) may be provided to enable direct water supply from the 70 to the hot water tank 60. In this case, when the water level of the hot water W2 in the hot water tank 60 drops below the detection position of the electrode rod longer than the electrode rod 622, the make-up water pump provided in the make-up water line is driven to make up the make-up water. The make-up water W can be directly supplied from the tank 70 to the hot water tank 60.

In the present embodiment, the heat source water W5 is used as the heat source fluid of the heat pump circuit 10, but the heat source fluid is not limited to the heat source water W5, and various fluids such as air and exhaust gas can be used. The heat source fluid itself lowers in temperature while applying heat (sensible heat) to the water supply W1 in the heat recovery heat exchanger 40, and itself while applying heat (sensible heat) to the refrigerant R of the heat pump circuit 10 in the evaporator 14. It is preferable to use a fluid that lowers the temperature.

The drive source of the compressor 11 of the heat pump circuit 10 is not limited to the electric motor. For example, the compressor 11 may be driven by a steam motor that uses steam to generate power, or may be driven by a gas engine. In this case, the output of the compressor 11 may be adjusted by adjusting the amount of steam supplied to the steam motor or the amount of gas supplied to the gas engine to adjust the flow rate of the refrigerant.

According to the water supply heating system 1 of the first embodiment described above, the effects shown in the following (1A) to (11A) are obtained.

(1A) In the water supply heating system 1 of the present embodiment, the compressor 11, the condenser 12, the expansion valve 13, and the evaporator 14 are connected in an annular shape by the refrigerant circulation line L9, and the compressor 11 is driven by the compressor 12. A steam compression type heat pump circuit 10 for taking out heat, a heat recovery heat exchanger 40, a heat source fluid line L5 for circulating heat source fluid in the order of heat recovery heat exchanger 40 and evaporator 14, and heat recovery heat exchange. A water supply line L1 that circulates water supply W1 in the order of the vessel 40 and the condenser 12, a refrigerant flow rate adjusting means that is controlled based on the degree of superheat of the gas refrigerant R flowing into the compressor 11 to adjust the refrigerant flow rate, and a condenser 12 It is provided with a water supply flow rate adjusting means for adjusting the water supply flow rate, which is controlled based on the hot water discharge temperature of the water supply water W1 flowing out from the water supply W1, and a control means for controlling the refrigerant flow rate adjusting means and the water supply flow rate adjusting means.
In this way, by first flowing the heat source water W5 as the heat source fluid through the heat recovery heat exchanger 40, the heat output of the heat recovery heat exchanger 40 is increased, and the preheating amount of the water supply W1 is increased. The higher the temperature of the heat source water, the greater the effect of increasing the heat output. Since the heat recovery amount of the heat recovery heat exchanger 40 increases, the heat recovery amount of the heat pump circuit 10 can be relatively reduced. When the same system heat output as when the heat source water W5 is passed in the order of the evaporator 14 and the heat recovery heat exchanger 40 is obtained, the output of the compressor 11 can be reduced to reduce the power consumption of the heat pump circuit 10. ..
At this time, by first flowing the heat source water W5 through the heat recovery heat exchanger 40, the temperature of the heat source water W5 flowing into the evaporator 14 decreases, but further control is added, that is, the flow rate of the refrigerant based on the degree of superheat. Due to the multiple effect of the combination of adjustment and adjustment of the water supply flow rate based on the hot water temperature, for example, the heat input of the evaporator 14 is increased by adjusting the refrigerant flow rate according to the low superheat degree setting, and the water supply flow rate according to the low hot water temperature setting. Due to the multiple effects of further increasing the heat output of the heat recovery heat exchanger 40 and increasing the heat output of the evaporator 14, the heat source water W5 is first flowed to the heat recovery heat exchanger 40 by adjusting the COP of the system. Can be greatly increased.

(2A) In the heat source fluid line L5 of the water supply heating system 1 of the present embodiment, the heat source fluid and the water supply W1 are heat-exchanged by the heat recovery heat exchanger 40 by the counterflow, and then the heat source fluid and the liquid are exchanged by the evaporator 14. This is a connection configuration in which the refrigerant R exchanges heat with a counterflow.
In this way, the heat source water W5 flows in the order of the heat recovery heat exchanger 40 and the evaporator 14, and the heat recovery heat exchanger 40 and the evaporator 14 each flow in a counterflow with respect to the flow direction of the water supply W1. Thereby, the heat recovery amount can be maximized.

(3A) The water supply heating system 1 of the present embodiment detects the suction temperature sensor 17 that detects the suction temperature of the gas refrigerant R flowing into the compressor 11 and the steam pressure of the gas refrigerant R flowing out of the evaporator 14. A steam pressure sensor 18 and a hot water temperature sensor 27 for detecting the hot water temperature of the water supply W1 flowing out of the condenser 12 are provided, and the control means obtains the evaporation temperature of the liquid refrigerant R from the detected pressure of the steam pressure sensor 18. , The evaporation temperature is subtracted from the detection temperature of the suction temperature sensor 17, the superheat degree of the gas refrigerant R is calculated, the refrigerant flow rate adjusting means is controlled so that the calculated superheat degree becomes the target superheat degree, and the hot water temperature sensor 27 is detected. The water supply flow rate adjusting means is controlled so that the temperature reaches the target hot water discharge temperature.
In this way, by accurately calculating the degree of superheat of the gas refrigerant R and keeping the value constant, the heat output of the condenser 12 with respect to the preheated water supply W1 is stabilized. This reduces fluctuations in the hot water flow rate. Further, for example, a high heat output can be maintained by appropriately increasing the water supply flow rate according to the set value of the target hot water temperature and keeping the flow rate within a certain range.

(4A) The water supply heating system 1 of the present embodiment includes a heat source temperature sensor that detects the temperature of the heat source fluid before flowing into the evaporator 14, and the control means controls the target overheating according to the detection temperature of the heat source temperature sensor. Set the degree.
In this way, by setting an appropriate target degree of superheat according to the temperature of the heat source fluid, it is possible to increase the amount of heat recovered by the evaporator 14 while preventing damage to the compressor 11 due to liquid compression.
For example, when the heat source water temperature is low, the refrigerant circulation flow rate increases by setting the target superheat degree low. As a result, the amount of heat recovered can be increased even with the low-temperature heat source water W5. By setting the lower limit of the target superheat degree to, for example, 5 ° C., damage to the compressor 11 due to liquid compression can be prevented. Further, by setting the upper limit value of the target superheat degree to, for example, 10 ° C., the refrigerant circulation flow rate can be maintained at a predetermined flow rate or higher, and a decrease in the heat recovery amount can be prevented.

(5A) The control means of the water supply heating system 1 of the present embodiment increases the target degree of superheat when it is determined that the fluctuation of the detection temperature of the heat source temperature sensor is large.
As a result, the heat pump circuit 10 can be stably driven even when a situation is confirmed in which the temperature of the heat source fluid suddenly changes.
For example, even when the temperature of the heat source fluid drops sharply, the refrigerant can be reliably vaporized by the evaporator 14 by setting the target superheat degree to a high value, so that the compressor 11 by liquid compression can be used. Damage can be prevented.

(6A) The control means of the water supply heating system 1 of the present embodiment reduces the target degree of superheat when it is determined that the detection temperature of the heat source temperature sensor is stable.
As a result, when the temperature of the heat source fluid is stable, the refrigerant circulation flow rate can be increased by setting the target superheat degree to a low value, and the amount of heat recovered by the evaporator 14 can be increased.

(7A) The water supply heating system 1 of the present embodiment includes a water supply temperature sensor that detects the temperature of the water supply before flowing into the condenser 12, and the control means is a target hot water discharge temperature according to the detection temperature of the water supply temperature sensor. To set.
In this way, by setting an appropriate target hot water temperature according to the temperature of the water supply, it is possible to prevent the occurrence of insufficient supercooling in the condenser 12 and excessive flow rate of the water supply.

(8A) The water supply heating system 1 of the present embodiment includes a water supply temperature sensor that detects the temperature of the water supply before flowing into the condenser 12, and the target hot water temperature is set to a value between the upper limit value and the lower limit value. It is possible, and the lower limit value is a value obtained by adding a predetermined value to the detection temperature of the water supply temperature sensor, and is a value higher as the detection temperature of the water supply temperature sensor becomes higher.
In this way, by setting the lower limit of the range of the target hot water temperature that can be set according to the water supply temperature, it is possible to surely prevent insufficient supercooling in the condenser 12 and reduce the amount of heat recovered in the evaporator 14. It can be stabilized. Further, it is possible to prevent the water supply flow rate from becoming excessive and suppress deterioration due to the overload of the water supply pump 21.

(9A) The water supply heating system 1 of the present embodiment is one that bypasses the water supply W1 to the heat recovery heat exchanger 40 and / or bypasses the heat source fluid to the heat recovery heat exchanger 40. Or two bypass lines, a water supply preheating mode in which the water supply W1 and the heat source fluid are simultaneously circulated to the heat recovery heat exchanger 40, and a preheating stop mode in which at least one of the water supply W1 and the heat source fluid is circulated in the bypass line. It is provided with a preheating mode switching means for switching.
As a result, the pressure loss of the water supply W1 and / or the heat source water W5 can be reduced by bypassing the heat recovery heat exchanger 40 under the condition that the heat recovery heat exchanger 40 cannot exert its effect, and the water supply pump 21 and the heat source can be used. The system COP including the feed pump 53 can be improved.

(10A) The water supply heating system 1 of the present embodiment includes a heat exchanger pre-inflow water supply temperature sensor 24 that detects the temperature of the water supply W1 before flowing into the heat recovery heat exchanger 40, and a heat recovery heat exchanger. A heat exchanger pre-inflow heat source temperature sensor 54 for detecting the temperature of the heat source fluid before flowing into 40 is provided, and the control means are a first detected temperature by the heat exchanger pre-inflow water supply temperature sensor 24 and a heat exchanger. The second detection temperature by the heat source temperature sensor 54 before inflow is compared, and when the first detection temperature is lower than the second detection temperature, the preheating mode switching means is controlled so as to execute the water supply preheating mode. When the first detection temperature exceeds the second detection temperature, the preheating mode switching means is controlled so as to execute the preheating stop mode.
The system COP can be maximized by automatically switching the preheating mode according to the water supply temperature and the heat source water temperature.

(11A) The control means of the water supply heating system 1 of the present embodiment is a signal input unit 150 that receives a preheating mode designation signal that specifies the type of water supply preheating mode or preheating stop mode, and preheating that is input to the signal input unit 150. It has a preheating mode switching control unit 140 that controls a preheating mode switching means so as to execute a water supply preheating mode or a preheating stop mode according to a mode designation signal.
The system COP can be maximized by switching the passive preheating mode according to such an external signal.

Further, according to the water supply heating system 1 of the first embodiment described above, the effects shown in the following (1B) to (8B) are also obtained.

(1B) In the water supply heating system 1 of the present embodiment, the compressor 11, the condenser 12, the expansion valve 13, and the evaporator 14 are connected in an annular shape by the refrigerant circulation line L9, and the condenser 12 is driven by the drive of the compressor 11. A steam compression type heat pump circuit 10 for taking out heat, a heat recovery heat exchanger 40, a heat source fluid line L5 for circulating a heat source fluid to a heat recovery heat exchanger 40 and an evaporator 14, and a heat recovery heat exchanger. The water supply line L1 that distributes the water supply W1 in the order of 40 and the condenser 12, the hot water tank 60 that stores the hot water W2 generated by the condenser 12, and the hot water W2 in the hot water tank 60 are transferred from the heat recovery heat exchanger 40. A recirculation line L2 that recirculates to the upstream side, a transient water flow mode in which hot water W2 is passed through the condenser 12 without flowing the hot water W2 through the recirculation line L2, and a condenser 12 while circulating hot water W2 through the recirculation line L2. It includes a water flow mode switching means for switching between a circulating water flow mode for passing water and a water flow stop mode for stopping water flow to the condenser 12, and a control means for controlling the water flow mode switching means.
In this way, by enabling the operation in the circulating water flow mode in addition to the transient water flow mode, the hot water tank 60 can be circulated and heated to maintain the hot water storage temperature as needed. In the circulating water flow mode, since the stored water flows in front of the heat recovery heat exchanger 40, efficient heating can be performed when the stored water temperature <heat source water temperature.

(2B) The water supply heating system 1 of the present embodiment is one that bypasses the water supply W1 to the heat recovery heat exchanger 40 and / or bypasses the heat source fluid to the heat recovery heat exchanger 40. Or two bypass lines, a water supply preheating mode in which the water supply W1 and the heat source fluid are simultaneously circulated to the heat recovery heat exchanger 40, and a preheating stop mode in which at least one of the water supply W1 and the heat source fluid is circulated in the bypass line. It is provided with a preheating mode switching means for switching.
As a result, the heat recovery heat exchanger 40 can be selectively used depending on the situation.

(3B) The control means of the water supply heating system 1 of the present embodiment can switch the preheating mode switching means between the water supply preheating mode and the preheating stop mode at least in the circulation water flow mode.
Thereby, for example, the heat recovery heat exchanger 40 can be positively utilized in the transient water flow mode, and the heat recovery heat exchanger 40 can be selectively utilized in the circulating water flow mode.

(4B) The heat source fluid line L5 of the water supply heating system 1 of the present embodiment has a connection configuration in which the heat source fluid is circulated in the order of the heat recovery heat exchanger 40 and the evaporator 14.
As a result, the amount of preheat of the water supply W1 can be increased by first flowing the heat source water W5 as the heat source fluid through the heat recovery heat exchanger 40, and the heat output of the heat recovery heat exchanger 40 can be increased. The higher the temperature of the heat source water, the greater the effect of increasing the heat output.

(5B) The water supply heating system 1 of the present embodiment includes a hot water temperature sensor 61 that detects the temperature of the hot water W2 in the hot water tank 60, and the control means supplies new water to the confluence of the recirculation line L2. Is executed, the water flow mode switching means is controlled so as to execute the transient water flow mode, new water supply to the merging point is stopped, and the detection temperature of the hot water temperature sensor 61 is the set temperature. If it is below, the water flow mode switching means is controlled so as to execute the circulation water flow mode, the new water supply to the merging point is stopped, and the detection temperature of the hot water temperature sensor 61 exceeds the set temperature. If so, the water flow mode switching means is controlled so as to execute the water flow stop mode.
As a result, when the demand for hot water is sufficient and the supply of make-up water W is required, the system can be operated in the over-passage mode in which the system COP is maximized. Further, when the demand for hot water is small and the supply of the make-up water W is not necessary, the temperature of the stored water can be raised in the circulating water flow mode when the temperature of the stored water in the hot water tank 60 drops.

(6B) The water supply heating system 1 of the present embodiment includes a heat exchanger pre-inflow water supply temperature sensor 24 that detects the temperature of the water supply W1 before it flows into the heat recovery heat exchanger 40, and a heat recovery heat exchanger. A heat exchanger pre-inflow heat source temperature sensor 54 for detecting the temperature of the heat source fluid before flowing into the heat exchanger 40 is provided, and the control means are the first detected temperature by the heat exchanger pre-inflow water supply temperature sensor 24 and the heat exchanger. The second detection temperature by the heat source temperature sensor 54 before inflow is compared, and when the first detection temperature is lower than the second detection temperature, the preheating mode switching means is controlled so as to execute the water supply preheating mode. When the first detection temperature exceeds the second detection temperature, the preheating mode switching means is controlled so as to execute the preheating stop mode.
The system COP can be maximized by automatically switching the preheating mode according to the water supply temperature and the heat source water temperature.

(7B) The control means of the water supply heating system 1 of the present embodiment is a first signal input unit that receives a water flow mode designation signal that specifies one of a transient water flow mode, a circulation water flow mode, and a water flow stop mode. Water flow that controls the water flow mode switching means so as to execute the transient water flow mode, the circulation water flow mode, or the water flow stop mode according to the water flow mode designation signal input to 151 and the first signal input unit 151. It has a mode switching control unit 130, and the water flow mode switching control unit 130 stops new water supply to the confluence point of the recirculation line L2 when the circulation water flow mode or the water flow stop mode is executed.
Thereby, for example, the system can be operated in the over-distribution mode in which the system COP is maximized by using an external signal with a supply of make-up water. In addition, it is possible to keep the stored water warm in the circulation mode by using an external signal without supplying make-up water.

(8B) The control means of the water supply heating system 1 of the present embodiment is a second signal input unit 152 that receives a preheating mode designation signal that specifies either a water supply preheating mode or a preheating stop mode, and a second signal input unit 152. The preheating mode switching control unit 140 controls the preheating mode switching means so as to execute the water supply preheating mode or the preheating stop mode according to the preheating mode designation signal input to.
As a result, for example, the passive preheating mode can be switched according to an external signal, and the system COP can be maximized.

Further, according to the water supply heating system 1 of the first embodiment described above, the effects shown in the following (1C) to (7C) are also obtained.

(1C) In the water supply heating system 1 of the present embodiment, the compressor 11, the condenser 12, the expansion valve 13, and the evaporator 14 are connected in an annular shape by the refrigerant circulation line L9, and the compressor 11 is driven by the condenser 12. The temperature of the heat source fluid that exchanges heat between the steam compression type heat pump circuit 10 that takes out heat, the refrigerant flow rate adjusting means that adjusts the flow rate of the refrigerant R flowing through the heat pump circuit 10, and the refrigerant R is detected by the evaporator 14. A heat source temperature sensor and a control means for controlling the refrigerant flow rate adjusting means are provided, and the control means sets a target degree of overheating according to the detection temperature of the heat source temperature sensor and overheats the refrigerant R flowing into the compressor 11. The refrigerant flow rate adjusting means is controlled so that the degree becomes the target degree of overheating.
In this way, by setting an appropriate target degree of superheat according to the temperature of the heat source fluid, it is possible to increase the amount of heat recovered by the evaporator 14 while preventing damage to the compressor 11 due to liquid compression.
For example, when the heat source water temperature is low, the refrigerant circulation flow rate increases by setting the target superheat degree low. As a result, the amount of heat recovered can be increased even if the heat source fluid is the low temperature heat source water W5. By setting the lower limit of the target superheat degree to, for example, 5 ° C., damage to the compressor 11 due to liquid compression can be prevented. Further, by setting the upper limit value of the target superheat degree to, for example, 10 ° C., the refrigerant circulation flow rate can be maintained at a predetermined flow rate or higher, and a decrease in the heat recovery amount can be prevented.

(2C) The control means of the water supply heating system 1 of the present embodiment increases the target degree of superheat when it is determined that the fluctuation of the detection temperature of the heat source temperature sensor is large.
As a result, the heat pump circuit 10 can be stably driven even when a situation is confirmed in which the temperature of the heat source fluid suddenly changes.
For example, even when the temperature of the heat source fluid drops sharply, the refrigerant can be reliably vaporized by the evaporator 14 by setting the target superheat degree to a high value, so that the compressor 11 by liquid compression can be used. Damage can be prevented.

(3C) The control means of the water supply heating system 1 of the present embodiment reduces the target degree of superheat when it is determined that the detection temperature of the heat source temperature sensor is stable.
As a result, when the temperature of the heat source fluid is stable, the refrigerant circulation flow rate can be increased by setting the target superheat degree to a low value, and the amount of heat recovered by the evaporator 14 can be increased.

(4C) The water supply heating system 1 of the present embodiment detects the suction temperature sensor 17 for detecting the suction temperature of the gas refrigerant R flowing into the compressor 11 and the vapor pressure of the gas refrigerant R flowing out from the evaporator 14. A vapor pressure sensor 18 is provided, and the control means obtains the evaporation temperature of the liquid refrigerant R from the detection pressure of the vapor pressure sensor 18, and subtracts the evaporation temperature from the detection temperature of the suction temperature sensor 17 to obtain the degree of superheat of the gas refrigerant R. Is calculated, and the refrigerant flow rate adjusting means is controlled so that the calculated superheat degree becomes the target superheat degree.
In this way, by accurately calculating the degree of superheat of the gas refrigerant R and keeping the value constant, the heat output of the condenser 12 with respect to the preheated water supply W1 is stabilized. This reduces fluctuations in the hot water flow rate.

(5C) The water supply heating system 1 of the present embodiment includes a water supply flow rate adjusting means for adjusting the water supply flow rate flowing through the condenser 12, and a hot water discharge temperature sensor 27 for detecting the hot water discharge temperature of the water supply W1 flowing out from the condenser 12. The control means controls the water supply flow rate adjusting means so that the detection temperature of the hot water temperature sensor 27 becomes the target hot water discharge temperature.
As a result, the water supply W1 can always be heated to a desired temperature and the hot water can be discharged.

(6C) The water supply heating system 1 of the present embodiment includes a water supply temperature sensor that detects the temperature of the water supply W1 before flowing into the condenser 12, and the control means is a target hot water discharge according to the detection temperature of the water supply temperature sensor. Set the temperature.
In this way, by setting an appropriate target hot water discharge temperature according to the temperature of the water supply W1, it is possible to prevent the occurrence of insufficient supercooling in the condenser 12 and excessive water supply flow rate.

(7C) The water supply heating system 1 of the present embodiment includes a water supply temperature sensor that detects the temperature of the water supply W1 before flowing into the condenser 12, and the target hot water temperature is set to a value between the upper limit value and the lower limit value. It can be set, and the lower limit value is a value obtained by adding a predetermined value to the detection temperature of the water supply temperature sensor, and is a value higher as the detection temperature of the water supply temperature sensor becomes higher.
In this way, by setting the lower limit of the range of the target hot water temperature that can be set according to the water supply temperature, it is possible to surely prevent insufficient supercooling in the condenser 12 and reduce the amount of heat recovered in the evaporator 14. It can be stabilized. Further, it is possible to prevent the water supply flow rate from becoming excessive and suppress deterioration due to the overload of the water supply pump 21.

Although the preferred embodiment of the water supply heating system of the present invention has been described above, the present invention is not limited to the above-described embodiment and can be appropriately modified.

1 Water supply heating system 10 Heat pump circuit 11 Compressor 12 Condenser
12A condenser
12B supercooler
13 Expansion valve (refrigerant flow rate adjusting means)
14 Evaporator 17 Suction temperature sensor 18 Steam pressure sensor 21 Water supply pump (water supply flow rate adjusting means, water flow mode switching means)
24 1st water supply temperature sensor (heat exchanger water supply temperature sensor before inflow, water supply temperature sensor)
25 Three-way valve (preheating mode switching means)
26 Second water supply temperature sensor (water supply temperature sensor)
27 Hot water temperature sensor 31 Reflux pump (water supply flow rate adjusting means, water flow mode switching means)
40 Heat exchanger for heat recovery 50 Heat source water tank 53 Heat source supply pump 54 First heat source temperature sensor (heat source temperature sensor before inflow of heat exchanger, heat source temperature sensor)
55 Second heat source temperature sensor (heat source temperature sensor)
60 Hot water tank 61 Hot water temperature sensor 62 Water level detection unit 63 Hot water supply pump 70 Makeup water tank 100 Control unit 111 Target superheat degree setting unit 112 Superheat degree calculation unit 113 Refrigerant flow control unit 121 Target hot water temperature settable range determination unit 122 Target hot water discharge Temperature setting unit 123 Water supply flow control unit 130 Water flow mode switching control unit 140 Preheating mode switching control unit 150 Signal input unit 151 1st signal input unit 152 2nd signal input unit L1 Water supply line L2 Reflux line L3 Bypass line L4 Hot water supply line L5 Heat source fluid line L9 Refrigerant circulation line R Refrigerant (gas refrigerant, liquid refrigerant)
W Make-up water W1 Supply water W2 Hot water W5 Heat source water (heat source fluid)

Claims (11)

A steam compression type heat pump circuit in which a compressor, a condenser, an expansion valve and an evaporator are cyclically connected by a refrigerant circulation line, and heat is taken out by the condenser by driving the compressor.
Heat exchanger for heat recovery and
A heat source fluid line that distributes the heat source fluid in the order of the heat recovery heat exchanger and the evaporator, and the heat source fluid line.
A water supply line that distributes water in the order of the heat recovery heat exchanger and the condenser,
A refrigerant flow rate adjusting means that is controlled based on the degree of superheat of the gas refrigerant flowing into the compressor and adjusts the refrigerant flow rate.
A water supply flow rate adjusting means that is controlled based on the temperature of the water supply flowing out of the condenser and adjusts the water supply flow rate.
A water supply heating system including the refrigerant flow rate adjusting means and a control means for controlling the water supply flow rate adjusting means. The heat source fluid line has a connection configuration in which the heat source fluid and the supply water are heat-exchanged by the counterflow in the heat recovery heat exchanger, and then the heat source fluid and the liquid refrigerant are heat-exchanged by the counterflow in the evaporator. Item 1. The water supply heating system according to item 1. A suction temperature sensor that detects the suction temperature of the gas refrigerant flowing into the compressor, and
A steam pressure sensor that detects the steam pressure of the gas refrigerant flowing out of the evaporator, and
A hot water temperature sensor that detects the hot water temperature of the supply water flowing out of the condenser is provided.
The control means
The evaporation temperature of the liquid refrigerant is obtained from the detection pressure of the vapor pressure sensor, and the superheat degree of the gas refrigerant is calculated by subtracting the evaporation temperature from the detection temperature of the suction temperature sensor, and the calculated superheat degree becomes the target superheat degree. By controlling the refrigerant flow rate adjusting means so as to
The water supply heating system according to claim 1 or 2, wherein the water supply flow rate adjusting means is controlled so that the detection temperature of the hot water discharge temperature sensor reaches the target hot water discharge temperature. A heat source temperature sensor for detecting the temperature of the heat source fluid before flowing into the evaporator is provided.
The water supply heating system according to claim 3, wherein the control means sets the target superheat degree according to the detection temperature of the heat source temperature sensor. The water supply heating system according to claim 4, wherein the control means increases the target degree of superheat when it is determined that the fluctuation of the detection temperature of the heat source temperature sensor is large. The water supply heating system according to claim 4 or 5, wherein when the control means determines that the detection temperature of the heat source temperature sensor is stable, the target superheat degree is reduced. A water supply temperature sensor for detecting the temperature of the water supply before flowing into the condenser is provided.
The water supply heating system according to any one of claims 3 to 6, wherein the control means sets the target hot water temperature according to the detection temperature of the water supply temperature sensor. A water supply temperature sensor for detecting the temperature of the water supply before flowing into the condenser is provided.
The target hot water temperature can be set to a value between the upper limit value and the lower limit value, and the lower limit value is a value obtained by adding a predetermined value to the detection temperature of the water supply temperature sensor, and is detected by the water supply temperature sensor. The water supply heating system according to any one of claims 3 to 6, wherein the higher the temperature, the higher the value. One or two bypass lines that bypass the water supply to the heat recovery heat exchanger and / or bypass the heat source fluid to the heat recovery heat exchanger.
A preheating mode switching means for switching between a water supply preheating mode in which the water supply and the heat source fluid are simultaneously circulated to the heat recovery heat exchanger and a preheating stop mode in which at least one of the water supply and the heat source fluid is circulated in the bypass line is provided. ,
The water supply heating system according to any one of claims 1 to 8. A heat exchanger pre-inflow water supply temperature sensor that detects the temperature of the water supply before it flows into the heat recovery heat exchanger, and
A heat exchanger pre-inflow heat source temperature sensor that detects the temperature of the heat source fluid before flowing into the heat recovery heat exchanger is provided.
The control means
The first detected temperature by the water supply temperature sensor before the inflow of the heat exchanger and the second detected temperature by the heat source temperature sensor before the inflow of the heat exchanger are compared.
When the first detection temperature is lower than the second detection temperature, the preheating mode switching means is controlled so as to execute the water supply preheating mode.
When the first detection temperature exceeds the second detection temperature, the preheating mode switching means is controlled so as to execute the preheating stop mode.
The water supply heating system according to claim 9. The control means
A signal input unit that receives a preheating mode designation signal that specifies the type of the water supply preheating mode or the preheating stop mode, and
9. A preheating mode switching control unit that controls the preheating mode switching means so as to execute the water supply preheating mode or the preheating stop mode according to the preheating mode designation signal input to the signal input unit. Water supply heating system described in.

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