JP6304996B2 - Water heater - Google Patents

Description

  The present invention relates to a hot water supply apparatus that heats a fluid using a heat pump.

  In a conventional hot water supply apparatus, a hot water supply having a heat pump apparatus that uses a heat pump (refrigeration cycle) as a heat source of the hot water supply apparatus to heat a fluid such as water that circulates in a water circuit or the like (hereinafter, water will be described as a representative). The device is known.

  In such a hot water supply apparatus, for example, a capacity control unit that controls the capacity of the compressor to be changeable, and a flow rate of water flowing through the water circuit by driving the feed water pump (hereinafter referred to as a water flow rate of the feed water pump) can be changed. There are some which have a flow control part to control (for example, refer to patent documents 1). For example, when the water temperature on the water inlet side of the refrigerant-water heat exchanger that exchanges heat between the refrigerant and water is equal to or lower than a predetermined temperature, the flow control unit fixes the water flow rate of the water supply pump and the capacity control unit compresses the water. Control to change the machine's ability. On the other hand, when the water temperature on the water inlet side of the refrigerant-water heat exchanger exceeds a predetermined temperature, the capacity control unit performs control to fix the capacity of the compressor and the flow rate control unit to vary the flow rate of the pump.

JP 2002-228276 A (FIG. 1)

  However, in the heat pump apparatus of the hot water supply apparatus as in the above cited reference 1, the saturation temperature obtained at the same saturation pressure (condensation pressure) differs depending on the refrigerant used in the heat pump. For this reason, in the case of a refrigerant in which the saturation pressure has to be increased in order to obtain a predetermined saturation temperature, the refrigerant piping or the like may be changed.

  For example, consider the case of sterilizing Legionella. In order to suppress the growth of Legionella in the hot water storage tank, 65 ° C. is secured as the hot water temperature. This is because if the water temperature is less than 55 ° C., the bactericidal effect due to heat cannot be expected. Here, in the hot water supply device, for example, in order to secure a hot water temperature of 65 ° C., when R407C is used as the refrigerant in the heat pump device and when R410A is used as the refrigerant, the condensing pressure is higher in R410A. .

  In the hot water supply device of the above cited document 1, one of the capacity of the compressor or the flow rate of the pump is fixedly controlled based on the water temperature on the water inlet side of the refrigerant-water heat exchanger. For this reason, the water temperature on the water inlet side of the refrigerant-water heat exchanger and the water temperature on the water outlet side cannot be controlled simultaneously (linked control), and the increase in the condensation pressure of the refrigerant could not be controlled. .

  The present invention has been made to solve the above-described problems, and an object of the present invention is to obtain a hot water supply apparatus that can discharge water at a higher temperature while suppressing an increase in the condensation pressure of the refrigerant. is there.

A hot water supply apparatus according to the present invention includes a variable capacity compressor that compresses a refrigerant, a refrigerant-water heat exchanger that performs heat exchange between the refrigerant and water, a decompression apparatus that depressurizes the refrigerant by adjusting an opening degree, and a refrigerant by heat exchange. An evaporator that evaporates water is connected to a pipe to form a refrigerant circuit, and a water flow variable feed water pump that forms a flow of water that passes through the refrigerant-water heat exchanger, and water that flows into the refrigerant-water heat exchanger The water inlet temperature detecting means for detecting the water inlet temperature, the water outlet temperature detecting means for detecting the water outlet temperature of the water flowing out from the refrigerant-water heat exchanger, and the water inlet temperature become a predetermined first temperature. A controller that variably controls the flow rate of the water supply pump so that the water outlet temperature becomes a predetermined second temperature, and the refrigerant capacity is fixed. The vessel has a flow direction of refrigerant and a flow of water. A heat exchanger flowing opposite the direction control device, and controls the water flow by the feed water pump so that the temperature of the detection of the water outlet temperature detection means becomes a second temperature, and the refrigerant - water The condensing temperature in the refrigerant-water heat exchanger is adjusted by controlling the compressor so that water flowing out from the heat exchanger circulates and the water inlet temperature flowing into the refrigerant-water heat exchanger becomes the first temperature. To do .

  According to the hot water supply apparatus of the present invention, for example, it is possible to heat water to a higher hot water temperature without changing the condensing pressure of the refrigerant with respect to a hot water supply load fluctuation at the site, and to maintain and control the high hot water temperature. it can.

It is a figure which shows the structure of the hot water storage system which has a heat pump apparatus in embodiment of this invention. It is a figure which shows the structure of the apparatus of the control system which concerns on embodiment of this invention. It is the schematic which shows the relationship between a water temperature when a hot water supply use load from a hot water storage tank falls, a compressor, and a water supply pump capability. It is a Ts diagram which shows the temperature change of the refrigerant | coolant and water which flow through the refrigerant | coolant-water heat exchanger which concerns on embodiment of this invention. It is a flowchart which shows the process sequence by the control apparatus 15 which concerns on embodiment of this invention.

Embodiment.
In the present embodiment, a hot water supply apparatus provided with a hot water storage tank will be described as an example of the hot water supply apparatus according to the present invention. Here, in FIG. 1 and the following drawings, the same reference numerals denote the same or corresponding parts, and are common to the whole text of the embodiments described below. And the form of the component represented by the whole specification is an illustration to the last, Comprising: It does not limit to the form described in the specification. In the drawings, the size relationship of each component may be different from the actual one. The level of temperature, pressure, etc. is not particularly determined in relation to absolute values, but is relatively determined in terms of the state and operation of the apparatus.

  FIG. 1 is a diagram showing a configuration of a hot water storage system having a heat pump device according to an embodiment of the present invention. In FIG. 1, the flow direction of the refrigerant is indicated by solid arrows, and the flow direction of water is indicated by broken arrows. As shown in FIG. 1, the hot water storage system of the present embodiment includes a heat pump device 1 and a water circuit 6. Heat is transferred between the heat pump device 1 and the water circuit 6 via a refrigerant / water heat exchanger 12 such as a plate type or a double pipe type. Here, it is assumed that the refrigerant-water heat exchanger 12 of the present embodiment is a counterflow type heat exchanger such that the refrigerant flow direction and the water flow direction are opposed to each other.

  The heat pump device 1 constitutes a heat pump circuit (refrigerant circuit) that circulates a refrigerant by connecting the compressor 2, the condenser 3, the decompression device 4, and the evaporator 5 by piping. And in the condenser 3, it becomes a heat source which heats the water which flows through the water circuit 6 by dissipating heat to the refrigerant and exchanging heat.

  The compressor 2 draws in refrigerant, compresses it, and discharges it. Based on control by the ability control means 13 described later, for example, the capacity (feeding amount per unit time) can be changed by arbitrarily changing the drive frequency. The refrigerant side flow path of the refrigerant-water heat exchanger 12 serves as a condenser (heat radiator) 3. The condenser 3 radiates heat to the refrigerant, and heats the water flowing through the water heat exchanger 9 that becomes the water-side flow path of the refrigerant-water heat exchanger 12. For example, the decompression device 4 having an expansion valve or the like decompresses the refrigerant flowing through the refrigerant circuit. The evaporator (cooler) 5 evaporates the refrigerant by exchanging heat between air and the refrigerant, for example.

  The water circuit 6 includes a water supply pump 7, a water heat exchanger 9, and a hot water tank 11. The water supply pump 7 pressurizes and circulates the water in the water circuit 6. Based on the control by the water flow rate control means 14 described later, for example, the flow rate of water flowing through the water circuit 6 can be changed by arbitrarily changing the drive frequency. Further, the water-side flow path of the refrigerant-water heat exchanger 12 serves as the water heat exchanger 9. The water heat exchanger 9 exchanges heat between the refrigerant flowing through the condenser 3 and water. Water is heated by heat exchange, and the refrigerant is cooled. The hot water storage tank 11 stores heated water (hot water). Further, a water inlet temperature detecting means 8 and a water outlet temperature detecting means 10 which are temperature sensors for detecting the temperature (water temperature) of water flowing into and out of the water heat exchanger 9 are attached to the water circuit 6.

  Here, operation | movement of each component apparatus of a hot water supply apparatus is demonstrated. First, operation | movement of each component apparatus by the side of the heat pump apparatus 1 is demonstrated based on the flow of the refrigerant | coolant which circulates through a refrigerant circuit. The compressor 2 compresses the sucked refrigerant and discharges it in a gas phase of high temperature and pressure. The refrigerant flows into the condenser 3. The discharged refrigerant flows into the condenser 3. In the condenser 3, the refrigerant is condensed and liquefied by heat exchange of water flowing through the water heat exchanger 9 (water circuit 6). The condensed and liquefied refrigerant passes through the decompression device 4. The decompression device 4 decompresses the condensed and liquefied refrigerant. The decompressed refrigerant flows into the evaporator 5. The evaporator 5 evaporates and gasifies the refrigerant by heat exchange with, for example, outdoor air (outside air). The compressor 2 sucks the evaporated gas refrigerant.

  Next, operation | movement of each component apparatus by the side of the water circuit 6 is demonstrated based on the flow of water. The water supply pump 7 is driven, and a water flow is generated in the water circuit 6. The water stored in the hot water tank 11 flows into the water heat exchanger 9. The water flowing into the water heat exchanger 9 is heated by heat exchange with the refrigerant passing through the condenser 3 of the heat pump device 1. The heated water flows out of the water heat exchanger 9 and returns to the hot water tank 11.

  FIG. 2 is a diagram showing the configuration of the control system apparatus according to the embodiment of the present invention. The capacity control means 13 includes, for example, an inverter circuit and adjusts the capacity (drive frequency) of the compressor 2. The water flow rate control means 14 has, for example, an inverter circuit, and adjusts the drive rotation speed (drive frequency) of the water supply pump 7 to adjust the water flow rate of the water supply pump.

  Moreover, in this Embodiment, it has the control apparatus 15 which controls the whole hot water supply apparatus. A signal including the water inlet temperature detected by the water inlet temperature detecting means 8 is input to the control device 15 in the present embodiment. Further, a signal including the water outlet temperature detected by the water outlet temperature detection means 10 is input. Then, a command signal related to the capacity of the compressor 2 is sent to the capacity control means 13. In addition, a command signal related to the water flow rate (drive rotational speed) of the water supply pump 7 is sent to the water flow rate control means 14.

  When the control device 15 determines that the water inlet temperature related to the detection by the water inlet temperature detecting means 8 is lower than a predetermined first temperature (for example, 55 ° C.), the control device 15 is capable of performing variable control on the capacity of the compressor 2. A command signal is sent to the control means 13. Further, the water flow rate of the water supply pump 7 is fixedly controlled, a command signal is sent to the water flow rate control means 14 so as to maintain the flow rate of the water circulating in the water circuit 6, and the water related to the detection by the water outlet temperature detection means 10. The outlet temperature is controlled to be a predetermined temperature (for example, 60 ° C.).

  When it is determined that the water inlet temperature related to the detection by the water inlet temperature detecting means 8 has reached the first temperature (for example, 55 ° C.), a command signal for fixedly controlling the capacity of the compressor 2 is controlled. Send to means 13. Further, by sending a command signal to the water flow rate control means 14 so as to variably control the water flow rate of the water supply pump 7, the water outlet temperature related to the detection by the water outlet temperature detection means 10 becomes the second temperature (for example, 65 ° C.). Control to become.

  Further, when the control device 15 determines that the temperature related to detection by the water inlet temperature detection means 8 exceeds a predetermined third temperature (for example, 57 ° C.), the control device 15 issues a command for performing variable control on the capability of the compressor 2. The temperature is sent to the means 13 so as to lower the condensation temperature, and the water inlet temperature related to detection by the water inlet temperature detecting means 8 is controlled to be the first temperature (for example, 55 ° C.). Further, a command is sent to the water flow rate control means 14 so as to variably control the water flow rate of the water supply pump 7 so that the water outlet temperature related to the detection by the water outlet temperature detection means 10 becomes the second temperature (for example, 65 ° C.). Control in conjunction with. Here, it is desirable that the third temperature is the same as the first temperature, but here the temperature is set slightly higher than the first temperature in consideration of control stability, temperature error, and the like.

  FIG. 3 is a schematic view showing the relationship between the water temperature and the compressor and feed water pump capacity when the hot water use load from the hot water storage tank is lowered. Here, Fig.3 (a) is a figure which shows the relationship in the hot water supply apparatus of this Embodiment. FIG.3 (b) is a figure which shows the relationship in the conventional hot water supply apparatus.

  For example, when the control in the compressor 2 and the feed water pump 7 are separately performed (not performed in conjunction with each other) as in the conventional hot water supply apparatus as shown in FIG. 3B, first, the water outlet temperature is determined. In order to maintain a high temperature, the capacity of the compressor 2 is reduced. And when the hot water supply use load decreases and the capacity of the compressor 2 reaches the minimum, the water outlet temperature is controlled to be maintained at a constant temperature by increasing the flow rate by the feed water pump 7. It was.

  However, during this time, the water inlet temperature rises. Furthermore, when the water inlet temperature rises, the temperature difference between the refrigerant passing through the condenser 3 and the water inlet temperature becomes smaller, and the condensation pressure rises as the condensation temperature rises.

  Therefore, in the hot water supply apparatus of the present embodiment, the capacity of the compressor 2 is reduced so that the water inlet temperature becomes the first temperature, and the flow rate of the water supply pump 7 is reduced so that the water outlet temperature becomes the second temperature. By performing the control to be interlocked, the water outlet temperature and the water inlet temperature are both maintained at desired temperatures while suppressing the condensation temperature, and the pressure increase of the refrigerant passing through the condenser 3 is suppressed.

  FIG. 4 is a Ts diagram showing temperature changes of refrigerant and water flowing through the refrigerant-water heat exchanger according to the embodiment of the present invention. The control device 15 sends a command signal to the capacity control means 13 so as to fix the capacity of the compressor 2 when the water inlet temperature detected by the water inlet temperature detection means 8 reaches a first temperature (for example, 55 ° C.). Send. Further, a command signal is sent to the water flow rate control means 14 so as to reduce the water flow rate of the water supply pump 7 to reduce the water flow rate. The heat exchange time is lengthened, and the water passing through the water heat exchanger 9 is heat exchanged to the superheated steam region of the refrigerant without increasing the refrigerant condensation temperature in the condenser 3 (increasing the refrigerant pressure). In other words, the water outlet temperature related to detection by the water outlet temperature detecting means 10 is raised to a second temperature (for example, 65 ° C.).

  FIG. 5 is a flowchart showing a processing procedure by the control device 15 according to the embodiment of the present invention. Based on FIG. 4, the operation | movement in the hot water supply apparatus of this Embodiment is demonstrated. First, in step S1, the compressor 2 and the water supply pump 7 are driven, and the operation of the hot water supply apparatus is started (step S1). In step S2, a command signal is sent to the water flow rate control means 14, and the water flow rate of the water supply pump 7 is fixedly controlled by a predetermined water flow rate (step S2). At this time, the flow rate of the water circuit 6 (the flow rate of water flowing into and out of the water heat exchanger 9) is also constant. In step S3, a command signal is sent to the capacity control means 13, and the capacity of the compressor 2 (so that the water outlet temperature related to detection by the water outlet temperature detection means 10 becomes constant at a predetermined temperature (for example, 60 ° C.)). The driving is variably controlled (step S3).

  Next, in step S4, it is determined whether or not the water inlet temperature related to detection by the water inlet temperature detecting means 8 is less than a first temperature (for example, 55 ° C.) (step S4). If it is determined that the temperature is lower than the first temperature, the process returns to step S3 and the same control process is continued until it is determined that the temperature is equal to or higher than the first temperature.

  On the other hand, if it is determined in step S4 that the water inlet temperature related to detection by the water inlet temperature detecting means 8 is equal to or higher than the first temperature, a command signal is sent to the capacity control means 13 in step S5, and the capacity of the compressor 2 is Is fixedly controlled (step S5). Further, in step S6, a command signal is sent to the water flow rate control means 14 so that the water outlet temperature related to detection by the water outlet temperature detecting means 10 becomes constant at the second temperature (for example, 65 ° C.). The water flow rate is variably controlled to control the flow rate through the water circuit 6 (step S6).

  When variable flow rate control of the feed water pump 7 is performed in step S6, it is determined in step S7 whether or not the water inlet temperature of the water inlet temperature detecting means 8 has exceeded a third temperature (for example, 57 ° C.) (step S7). ). If it determines with not having exceeded 3rd temperature, it will return to step S6 and the water flow rate of the feed water pump 7 will be variably controlled so that water outlet temperature may become fixed with 2nd temperature.

  For example, the case where the hot water supply use load falls and the temperature of the water (hot water) stored in the hot water storage tank 11 rises is assumed. If it is determined that the temperature exceeds the third temperature, in step S8, a command signal is sent to the capacity control means 13, and the water inlet temperature related to the detection by the water inlet temperature detection means 8 is constant at the first temperature (eg, 55 ° C.). Then, the variable control of the capacity of the compressor 2 is performed (step S8). At this time, the water supply pump 7 continues the variable control in which the water outlet temperature related to the detection by the water outlet temperature detecting means 10 is constant at the second temperature (for example, 65 ° C.).

  Next, in step S9, it is determined whether or not the water inlet temperature related to detection by the water inlet temperature detecting means 8 is lower than a first temperature (for example, 55 ° C.) (step S9). If it is determined that the temperature is not lower than the first temperature, the process returns to step S6 and the same control process is continued until it is determined that the temperature is lower than the first temperature.

  On the other hand, if it is determined in step S9 that the water inlet temperature related to detection by the water inlet temperature detecting means 8 has become lower than the first temperature, the process returns to step S4, and the capacity of the compressor 2 is fixed to the capacity control means 13. A control command signal is sent to continue the control process.

  As described above, according to the hot water supply apparatus of the present embodiment, by controlling the flow rate of the water supply pump 7, the temperature of the water flowing out of the water heat exchanger 9 is changed to the superheated steam of the refrigerant flowing into the condenser 3. The temperature can be raised to near the temperature. At this time, if the water inlet temperature rises, the compressor 2 and the feed water pump 7 are controlled in conjunction with each other, for example, the compressor 2 is variably controlled to lower the condensation temperature, so that the water flowing into the water heat exchanger 9 is controlled. Both the temperature and the temperature of the outflowing water can be controlled.

  DESCRIPTION OF SYMBOLS 1 Heat pump apparatus, 2 Compressor, 3 Condenser, 4 Decompression apparatus, 5 Evaporator, 6 Water circuit, 7 Water supply pump, 8 Water inlet temperature detection means, 9 Water heat exchanger, 10 Water outlet temperature detection means, 11 Hot water storage Tank, 12 Refrigerant-water heat exchanger, 13 Capacity control means, 14 Water flow rate control means, 15 Control device.

Claims (4)

Variable capacity compressor for compressing refrigerant, refrigerant-water heat exchanger for exchanging heat between the refrigerant and water, a decompression device for depressurizing the refrigerant by opening adjustment, and an evaporator for evaporating the refrigerant by heat exchange Connect the pipes to configure the refrigerant circuit,
A water supply variable feed pump that forms a flow of water that passes through the refrigerant-water heat exchanger;
Water inlet temperature detection means for detecting the water inlet temperature of the water flowing into the refrigerant-water heat exchanger;
Water outlet temperature detecting means for detecting the water outlet temperature of the water flowing out of the refrigerant-water heat exchanger;
When it is determined that the water inlet temperature has reached a predetermined first temperature, the capacity of the compressor is fixedly controlled so that the water outlet temperature becomes a predetermined second temperature. A control device that variably controls the water flow rate,
The refrigerant-water heat exchanger is a heat exchanger in which a direction in which the refrigerant flows and a direction in which the water flows are opposed to each other,
The control device controls the water flow rate by the feed water pump so that the temperature related to detection by the water outlet temperature detection means becomes the second temperature, and the water flowing out from the refrigerant-water heat exchanger is Circulating, adjusting the condensing temperature in the refrigerant-water heat exchanger by controlling the compressor so that the water inlet temperature flowing into the refrigerant-water heat exchanger becomes the first temperature. A hot water supply device. The controller is
When it is determined that the temperature related to detection by the water inlet temperature detection means exceeds the third temperature set to be equal to or higher than the first temperature, control is performed to reduce the capacity of the compressor, and the water outlet temperature is The hot water supply apparatus according to claim 1, wherein the water flow rate is variably controlled by the water supply pump so that the second temperature is reached.   The hot water supply according to claim 1 or 2, wherein the control device performs variable control of a water flow rate by the water supply pump so that a temperature related to detection by the water outlet temperature detection means becomes the second temperature. apparatus. The control device, from the start of the operation until it is judged that the water inlet temperature is the first temperature, claim 1-3, characterized in that fixed control the water supply pump The hot water supply apparatus according to one item.

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