JP6038402B2 - Vapor compression refrigeration cycle - Google Patents

Description

  The present invention relates to an intermediate injection type refrigeration cycle using HFO refrigerants such as HFO-1234yF and HFO-1234ze, which are low GWP refrigerants, and particularly to improvement of the operation efficiency thereof.

Conventionally, for example, the use of specific chlorofluorocarbons that have been used in water heaters and air conditioners has been subject to regulations due to concerns about the destruction of the ozone layer and global warming. In Europe, conversion to low GWP refrigerant is being promoted due to F-gas regulations. From such a background, it is expected that the existing refrigerant such as HFC will be converted to an HFO refrigerant in the future.
However, this HFO refrigerant has a disadvantage that the refrigerant at the compressor outlet has a low density, a low latent heat amount, and a low discharge temperature as compared with the conventional HFC refrigerant. For this reason, when this refrigerant is used for hot water supply and heating, the COP is reduced, that is, the operation efficiency is reduced.

  By the way, about the efficiency improvement of this refrigerating cycle operation, the refrigerant | coolant efficiency is improved by the intermediate injection system as one method, but the coefficient of performance COP (Coefficient of Performance) by the intermediate injection circuit in this main refrigeration cycle by it is performed. This improvement is realized by improving the efficiency of the compressor and improving the cycle efficiency. Generally, to improve this cycle efficiency, the refrigerant temperature is raised. When the refrigerant temperature is raised, the refrigerant circulation amount on the gas cooler side is increased and the heating capacity and the COP are improved. As one specific method for realizing this, for example, an intermediate injection port inlet may be provided in advance on the side surface of the compressor, and a refrigerant in a heated gas state may be injected from this portion.

  Regarding this intermediate injection system, the relationship between the refrigerant suction SH (superheat: superheat degree) at the intermediate injection port of the compressor and the refrigerant discharge temperature at the compressor outlet is shown in FIG. From this, it can be confirmed that as the suction SH at the intermediate injection port of the compressor increases, the refrigerant discharge temperature at the compressor outlet, and consequently the coefficient of performance COP of the refrigeration cycle, improve.

As this type of conventional example, there is one shown in Patent Document 1,
As for the outline of the conventional vapor compression refrigeration cycle, a compressor having an injection port serving as a refrigerant passage in the middle part of the compression stroke for compressing and discharging the sucked refrigerant, a four-way valve, a heat source side expansion device, a heat source side It comprises a heat exchanger, a load side expansion device, and a load side heat exchanger, which are connected in an annular shape so that the refrigerant circulates.
(See Patent Document 1)

  The configuration of the vapor compression refrigeration cycle disclosed in Patent Document 1 will be described below with reference to FIG. This configuration is basically the same except for the above-mentioned Patent Document 1 and specific components (liquid receiver 4), and FIG. 1 will be used as appropriate in the description of the configuration of the prior art.

  This vapor compression refrigeration cycle is a vapor compression refrigeration cycle 100 having an intermediate injection port 16 for injecting HFO as a new refrigerant into the compressor 1, and the compressor 1 and the heat on the high temperature side. A refrigeration cycle constructed by connecting a condenser 3 as an exchanger, an expansion valve 8 as a second expansion device, and an evaporator 7 as a low-temperature heat exchanger with refrigerant piping, and this refrigeration cycle The compressor 1, the condenser 3, the expansion valve 8, and the evaporator 7 are connected to each other by a refrigerant pipe for circulating the refrigerant. .

  The operation of the vapor compression refrigeration cycle according to Patent Document 1 will be described with reference to the PH diagram (pressure-specific enthalpy diagram) in FIG. In this PH diagram, the vertical axis indicates the refrigerant pressure P and the horizontal axis indicates the specific enthalpy H of the refrigerant. FIG. 11 shows a saturation curve (C) composed of a saturated liquid line and a saturated vapor line. , And a PH line (L).

First, the outline of the PH line (L) corresponding to the above-mentioned Patent Document 1 will be described. The outline is a substantially unequal leg trapezoidal part (the former) whose upper side is longer than the lower side, and its unequal leg trapezoid. The two figures are combined with the parallelogram part (the latter) in contact with the upwardly rising part so as to be included in the part.
In the former, the straight line pd is composed of the upper side, the straight line de is composed of the short leg side, the straight line ef is composed of the lower side (lower side <upper side), and the straight line fp is composed of the long leg side. In the latter, the straight line ap is composed of the upper side, the straight line pi is composed of the right side, the straight line ij is composed of the lower side, and the straight line ja is composed of the left side. Since b and c overlap and are the same point, b and c are displayed.

  Moreover, the part of the dashed-dotted line described inside the substantially unequal leg trapezoid corresponds to the intermediate injection. The portion of the alternate long and short dash line is composed of a straight line b-g parallel to the straight line de and a straight line gh parallel to the straight line ef. Further, i and j are located on an extension line of the straight line gh.

  Here, each of a to j located in FIG. 11 corresponds to each of a to j of the refrigeration cycle in FIG. In FIG. 1, each of a to j indicates a position on the configuration of the refrigeration cycle. In FIG. 11, a to j indicate the state of the refrigerant corresponding to these positions.

  In FIG. 11, a indicates the state of the refrigerant corresponding to the outlet of the compressor 1, where the pressure is Pa and the specific enthalpy is Ha.

During the period from a to b, the state a shifts to a state b located in the left direction parallel to the horizontal axis along the solid line. This corresponds to the fact that when the refrigerant passes through the condenser 3, it condenses from the gas state to the liquid state, thereby releasing the heat and reducing the enthalpy. In the state b (c), compared with the state a, the pressure Pb is unchanged, the pressure is Pb (Pc) = Pa, and the specific enthalpy is reduced to Hb (Hc).
c shows the state of the refrigerant flowing through the inlet of the second expansion device 8, and c is plotted at the same position as b. Here, in the PH diagram of FIG. 11, b and c are plotted at the same position, although the position of the refrigerant flowing in the refrigerant pipe is different in the configuration shown in FIG. 1, but shown in FIG. This is because the state of the refrigerant (pressure, specific entropy) on the PH diagram is the same.

  During the period from c to d, the state c shifts to a state d located in the left direction parallel to the horizontal axis along the solid line. This is because when the refrigerant passes through the internal heat exchanger 5, the main refrigerant pipe connected to the evaporator 7 and the sub refrigerant pipe (described later) connected to the injection port 16 exchange heat with each other. That is, the main refrigerant pipe releases heat and the sub refrigerant pipe absorbs heat. The refrigerant flowing through the main refrigerant pipe corresponds to reducing its enthalpy. In the state d, as compared with the state c, the pressure Pd remains unchanged, Pd = Pc, and the specific enthalpy decreases to Hd.

  During the period from d to e, the state d shifts to a state e located in a downward direction parallel to the vertical axis along the solid line. This corresponds to the fact that the refrigerant expands when the refrigerant passes through the first expansion device 6, thereby reducing the pressure. In the state e, as compared with the state d, the specific enthalpy is unchanged, He = Hd, and the pressure is reduced to Pe.

  During the period from e to f, the state e shifts to a state f located in the right direction parallel to the horizontal axis along the solid line. This corresponds to the fact that when the refrigerant passes through the evaporator 7, it absorbs heat by condensing from the liquid state to the gas state, and this refrigerant increases the enthalpy. In the state f, as compared with the state e, the pressure Pf is unchanged, Pf = Pe, and the specific enthalpy increases to Hf.

  During the period from f to i, the state f shifts to a state i positioned in the upper right direction along a straight solid line that rises to the right. This corresponds to the refrigerant 1 increasing its pressure and enthalpy by condensing the refrigerant to an intermediate pressure inside the compressor 1. In the state i, the pressure Pf increases to Pi, and the specific enthalpy Hf increases to Hi.

  Similarly, during a period from b (c) to g corresponding to the intermediate injection, the state b (c) shifts to a state g positioned in the downward direction parallel to the vertical axis along the alternate long and short dash line. This corresponds to the fact that when the refrigerant passes through the second expansion device 8, the pressure expands due to the refrigerant expanding. In the state g, as compared with the state c, the specific enthalpy is unchanged, Hg = Hc, and the pressure is reduced to Pg.

  During the period from g to h, the state g shifts to a state h located in the right direction parallel to the horizontal axis along the alternate long and short dash line. This corresponds to the fact that when the refrigerant passes through the internal heat exchanger 5, the refrigerant absorbs heat by heat exchange, and this refrigerant increases its enthalpy. In the state h, as compared with the state g, the pressure Ph remains unchanged, Ph = Pg, and the specific enthalpy increases to Hh. Here, h is on the saturation curve (C) line or inside the C line.

  During the period from h, i to j, h, i, j are on the same straight line, and the state h moves toward the state j in the right direction along the alternate long and short dash line, On the contrary, the state moves to a state j where i is located in the left direction parallel to the horizontal axis along the one-dot chain line toward j. This is because the refrigerant of the two systems, the refrigerant supplied via the main refrigerant pipe and the refrigerant supplied via the sub refrigerant pipe, are mixed inside the compressor 1 and subjected to heat averaging, resulting in a total refrigerant. This corresponds to the enthalpy of being averaged. In the state j, as compared with the state i, the pressure Pj is unchanged and Pj = Ph = Pi, and the specific enthalpy Hj is an average value of Hh and Hi.

  During the period from j to a, the state j shifts to a state a located in the upper right direction along a straight solid line rising upward. As the compressor 1 compresses the refrigerant from medium pressure to high pressure, the refrigerant increases pressure and enthalpy. In the state a, the pressure Pj increases to Pa, and the specific enthalpy Hj increases to Ha.

Thus, the pressure is Pa and the specific enthalpy is Ha, the refrigerant returns to the original refrigerant state a flowing through the outlet of the compressor 1, and one cycle is completed.
As is clear from the above description, in the PH line (L) diagram, the first compression step in the period from f to i and the second in the period from j to a are shown. There are two compression processes of the compression process, and a portion corresponding to both of the two compression processes is simply referred to as a compression process.

Japanese Unexamined Patent Publication No. 2013-15264 (paragraph 0014, FIG. 1)

  However, in the conventional intermediate injection system shown in FIG. 11, the suction SH is not sufficiently given to the refrigerant injected from the injection port 16. That is, in FIG. 11, h is on the curve of the saturated vapor line, j is slightly on the right side of the saturated vapor line, and is on the left side of the compression process in the PH diagram for the vapor compression refrigeration cycle. For this reason, the portion corresponding to the compression process in the PH diagram does not exist at an appropriate position on the PH diagram. That is, this is because the control device 18 does not sufficiently give the intake SH to the refrigerant inside the compressor 1 and the expansion valve 8 cannot be controlled so that j is located on the right side of the saturated vapor line.

  For this reason, it is necessary to heat up the circulating water temperature on the secondary side to a predetermined temperature (for example, 60 ° C.) using the heat generated from the condenser 3 which is a high-temperature side heat exchanger. In order to obtain heat for operation, there is a limit in the operation by this conventional injection method.

  Thus, instead of the conventional HFC, in the refrigeration cycle using the HFO refrigerant as a new refrigerant, the discharge temperature at the outlet of the compressor is greatly reduced, so there is a limit to its hot water supply capacity naturally, Even if the injection amount is determined according to the above proposal, the performance improvement effect and the reliability improvement effect due to the intermediate injection cannot be sufficiently obtained.

  The present invention was made to solve the above-mentioned problems, and even when using an HFO refrigerant that tends to lower the discharge temperature on the compressor outlet side, the refrigerant discharge temperature is prevented from lowering, A highly efficient hot water supply / heating refrigeration cycle is obtained.

The vapor compression refrigeration cycle of the present invention is
A vapor compression refrigeration cycle using HFO as a refrigerant,
The vapor compression refrigeration cycle is
A compressor provided with an injection port for injecting refrigerant circulating in the vapor compression refrigeration cycle;
A pressure sensor and a temperature sensor for measuring the pressure and temperature close to the injection port;
An expansion device that opens and closes the refrigerant so as to compress and expand;
A control device for controlling the opening degree of the expansion device based on the pressure and temperature obtained by the pressure sensor and the temperature sensor,
In the control device, the portion corresponding to the compression step in the PH diagram relating to the vapor compression refrigeration cycle is located outside the saturation curve composed of the saturated liquid line and the saturated vapor line, and from the critical pressure. Is located on the lower enthalpy region side than the saturated vapor line and is supplied via the main refrigerant pipe, and is supplied via the sub refrigerant pipe connected to the injection port. The state in which the two refrigerants are mixed and heat averaged in the compressor is positioned on the higher enthalpy region side than the state in which the compressor compresses the refrigerant to an intermediate pressure inside the compressor. to, and controls the expansion device.

  The vapor compression refrigeration cycle according to the invention keeps the temperature of the refrigerant injected into the intermediate injection compressor in an appropriate overheated state inside the compressor, and even when using the HFO refrigerant, It is possible to prevent the discharge temperature from being lowered at the outlet of the compressor caused by the injection, and to improve the operating efficiency (COP) of the refrigeration cycle.

1 is a circuit diagram of a vapor compression refrigeration cycle 100 showing Embodiment 1 of the present invention. FIG. 3 is a PH diagram illustrating a state of a refrigerant according to the first embodiment. FIG. 6 is a PH diagram showing an image of an increase in discharge temperature when heating refrigerant is supplied to the intermediate injection port 16. It is an opening degree control flowchart of the 2nd expansion device 8 concerning Embodiment 1. FIG. It is a circuit diagram of the vapor | steam compression refrigerating cycle 200 at the time of using the ventilation type heat exchanger 10 based on Embodiment 2. FIG. FIG. 10 is a block diagram showing an outline of a signal flow according to the second embodiment. FIG. 10 is a circuit diagram of a vapor compression refrigeration cycle 300 when exhaust heat from a control panel is used according to a modification of the second embodiment. 6 is a circuit diagram of a vapor compression refrigeration cycle 400 when exhaust heat of the compressor 1 is used according to Embodiment 3. FIG. FIG. 10 is a block diagram illustrating an outline of a signal flow according to a third embodiment. FIG. 6 is a circuit diagram of a vapor compression refrigeration cycle 500 when using gas refrigerant injection in a liquid receiver 4 according to a fourth embodiment. It is a PH diagram which shows the state of the refrigerant | coolant which concerns on the conventional injection circuit 9. FIG. The relationship between inhalation SH and the coefficient of performance COP in the intermediate injection port 16 is shown.

Embodiment 1 FIG.
FIG. 1 shows an entire vapor compression refrigeration cycle 100 according to Embodiment 1 of the present invention. Hereinafter, as an example, a hot water supply refrigeration cycle installed as a home water heater or a building water heater will be described.

  Prior to describing a specific detailed configuration, first, the vapor compression refrigeration cycle 100 and main circuits constituting it will be described.

Hereinafter, the first embodiment will be specifically described with reference to FIG.
The vapor compression refrigeration cycle 100 includes a compressor 1 that compresses a refrigerant, a four-way valve 2 that changes the flow direction of the refrigerant, a condenser 3, a liquid receiver 4 that is a high-pressure container that stores high-pressure liquid refrigerant, An internal heat exchanger 5 to be exchanged, an evaporator 7, a first expansion device 6 and a second expansion device 8 for expanding the refrigerant, and an injection circuit 9 for heating the refrigerant injected from the injection port 16 Has been.
Further, a pressure sensor 13 and a temperature sensor 14 for measuring the pressure and temperature of the refrigerant are provided in the vicinity of the inlet of the injection port 16, and a control device 18 for controlling the opening degree of the second expansion device 8 is further provided. Is provided. The control device 18 has a function of controlling the opening degree of the second expansion device 8 based on the refrigerant information obtained by the pressure sensor 13 and the temperature sensor 14.

  The liquid receiver 4 is installed in the middle path of the pipe connecting the output side of the condenser 3 and the input side of the second expansion device 8, and the gas-liquid two-phase flow stored in the liquid receiver 4 The refrigerant in the state is branched from the middle of the main refrigerant pipe described later. Of the refrigerant in the gas-liquid two-phase flow state stored in the liquid receiver 4, one is the upper inlet of the internal heat exchanger 5 through the second expansion device 8, and the other is the internal heat exchanger 5. Flows into the lower entrance.

  The internal heat exchanger 5 includes, inside, a main refrigerant pipe connecting the liquid receiver 4 and the expansion device 6, and a sub refrigerant pipe connecting the liquid receiver 4 and the expansion device 6 via the second expansion device 8. These two refrigerant pipes are arranged close to each other, and heat exchange is performed between the refrigerant flowing through the main refrigerant pipe and the refrigerant flowing through the sub refrigerant pipe. As a result, heat is released from the main refrigerant pipe to the sub refrigerant pipe, heat is absorbed from the sub refrigerant pipe to the main refrigerant pipe, the temperature of the refrigerant flowing through the main refrigerant pipe decreases, and the refrigerant flowing through the sub refrigerant pipe Temperature rises.

  The first expansion device 6 and the second expansion device 8 use expansion valves so as to compress and expand the refrigerant in the main refrigerant pipe and the sub refrigerant pipe, respectively. The injection circuit 9 heats the refrigerant that is injected into the compressor 1 from the injection port 16 including the sub refrigerant pipe.

  The injection port 16 is formed on the side surface of the compressor 1 in order to inject the refrigerant in a heated gas state into the compressor 1. Further, the pressure sensor 13 and the temperature sensor 14 are installed in the vicinity of the injection port 16 and measure the pressure and temperature of the refrigerant. A temperature sensor 17 is also installed at the inlet of the internal heat exchanger 5. Furthermore, the outside air temperature sensor 15 is disposed in the vicinity of the condenser 3 and measures the air temperature in the vicinity of the condenser 3.

  The control device 18 is connected to the second expansion device 8 via a communication line or the like, and based on the refrigerant information obtained by the pressure sensor 13 and the temperature sensor 14, the second expansion device. 8 is controlled. For example, the control device 18 is configured so that the refrigerant injected from the compressor injection port is heated steam having a superheat degree of 20 ° C. or higher and a high-low pressure ratio inside the compressor of 0.35 or higher. The opening degree of the second expansion device 8 is controlled.

  The condenser 3 corresponds to a heat exchanger on the high temperature side, and the high heat obtained by the condenser 3 is used as a heat source for high temperature on the secondary side. Similarly, the evaporator 7 corresponds to a low-temperature heat exchanger, and the low heat obtained by the evaporator 7 is used as a low-temperature heat source on the secondary side.

First, an outline of the PH line (L) of this embodiment will be described.
The operation of the vapor compression refrigeration cycle of the present invention will be described later, but the outline thereof is conventional except that the states h and j shown in FIG. 11 are shifted to the right (shifted to the high enthalpy region side). The description is omitted because it is the same as the PH diagram of FIG. 2, and the differences from the prior art will be mainly described with reference to FIG.

The approximate shape of the PH line (L) in FIG. 2 is in contact with a substantially uneven trapezoidal trapezoidal part (the former) whose upper side is longer than the lower side, and an upwardly shouldered part of the unequal legged trapezoidal part. The point that two figures with the parallelogram portion (the latter) are synthesized is the same, but the latter is different in that it is outside the former.
Also, each of a to j (refrigerant state) located in FIG. 2 corresponds to each of the refrigeration cycle a to j (position on the configuration of the refrigeration cycle) in FIG. Although the points are the same, the operation of the vapor compression refrigeration cycle of the present invention is different in that it corresponds to FIG.

  The operation period of the vapor compression refrigeration cycle of the present invention is divided into a first period (a period from a to g), a second period (a period from g to h), and a third period (h to a It is divided into three periods). Of these, the first period and the third period are the same as in the prior art. Here, the second period (the period from g to h) different from the prior art will be described mainly.

During the period from g to h, the state g shifts to a state h located in the right direction parallel to the horizontal axis along the alternate long and short dash line. This corresponds to the fact that when the refrigerant passes through the internal heat exchanger 5, the refrigerant absorbs heat by heat exchange, and this refrigerant increases its enthalpy. In the state h, as compared with the state g, this corresponds to the fact that the pressure Ph remains unchanged, Ph = Pg, and the specific enthalpy increases to Hh. Here, h is outside the saturation curve (C) line.
That is, during the period from the point g to the point h, the state g moves further along the alternate long and short dash line in the right direction parallel to the horizontal axis as described in FIG. This indicates that when the refrigerant passes through the internal heat exchanger 5, the refrigerant absorbs more heat than described in FIG. 11 by heat exchange, and the refrigerant that has absorbed this heat The enthalpy of the refrigerant supplied from the injection port 16 and inside the compressor 1 is further increased.

  More specifically, states h and j are shifted to the high enthalpy region side (right side) as compared with the conventional PH diagram previously described with reference to FIG. That is, it can be seen that the specific enthalpy of the refrigerant is increased in the compressor 1 in the first embodiment of the present invention.

As described above, in the PH diagram of FIG. 2 relating to the vapor compression refrigeration cycle 100, the portions corresponding to these two compression steps are both present in the region satisfying the following three conditions.
Condition 1: It is located outside a saturation curve (C) composed of a saturated liquid line and a saturated vapor line.
Condition 2: Located below the critical pressure. (In other words, the states h and j on the PH line (L) are below the states a and p)
Condition 3: It is located on the high enthalpy region side sufficiently from the saturated vapor line. (In other words, the states h and j on the PH line (L) are on the right side of the state i)
That is, this is because the control device 18 controls the opening / closing operation of the expansion valve 8 so that the refrigerant SH is sufficiently provided with the suction SH inside the compressor 1 and the point j is located on the right side of the saturated vapor line. It is none other than being.

  Further, the portion of the straight line a-p from the point a to the point p indicates the increase ΔH in the refrigerant discharge temperature. (See FIG. 3).

  In the vapor compression refrigeration cycle 100, the adjustment of the refrigerant temperature by the opening degree control of the second expansion device 8 is realized by performing the processing procedure shown in FIG. 4 (hereinafter, step S1 to step S5). This will be described with reference to FIG.

  When the operation command for the vapor compression refrigeration cycle 100 is turned ON, the outside air temperature sensor 15 detects the air temperature in the vicinity of the condenser 3. (Step S1).

  The control device 18 detects the pressure value of the refrigerant from the pressure sensor 13 and acquires the temperature of the refrigerant from the temperature sensor 15. Thereafter, the control device 18 calculates the saturation temperature of the refrigerant at the pressure based on the pressure value obtained from the pressure sensor 13. (Step S2).

  When the calculation of the saturation temperature of the refrigerant is completed in step S2, the control device 18 compares the saturation temperature with the temperature obtained by the temperature sensor 17 installed at the inlet of the internal heat exchanger 5 to overheat the refrigerant. The degree SH is calculated. (Step S3). Here, the superheat degree SH is a temperature difference between the temperature on the inlet side of the internal heat exchanger 5 and the temperature on the outlet side.

  Next, the superheat degree SH is compared with a superheat degree target value SHs that is a preset target value, and the control device 18 determines the opening degree of the second expansion device 8 based on the comparison result.

As a result of comparing the superheat degree SH with the superheat degree target value SHs, when the superheat degree target value SHs is larger than the superheat degree SH (superheat degree target value SHs> superheat degree SH), the opening degree of the second expansion device 8 When the superheat degree target value SHs is smaller than the superheat degree SH (superheat degree target value SHs <superheat degree SH), the opening degree of the second expansion device 8 is controlled to be increased. (Step S4).
Here, in step S <b> 4, the control device 18 instructs the second expansion device 8 to determine the opening degree of the second expansion device 8 and the determination result.

In step S4, the control device 18 further determines whether or not control is necessary after performing the opening degree control of the second expansion device 8. That is, it is determined whether or not the continuous operation of the vapor compression refrigeration cycle 100 is necessary. If further continuous operation is necessary, the process proceeds to YES and returns to S1. If the continuous operation is not necessary, the process proceeds to NO and control is performed. The opening control of the second expansion device 8 by the device 18 is finished. (Step S5).
Here, step S5 is a step of determining whether or not the opening degree of the second expansion device 8 is calculated again.

  Thereafter, the processes in steps S1 to S5 are repeated.

Embodiment 2. FIG.
In the vapor compression refrigeration cycle 200 showing the second embodiment of the present invention, the system configuration, the PH diagram, and the control flow are basically the same as those in the first embodiment, and are therefore omitted. 5 will be mainly described with reference to FIG.

  In the second embodiment, a blower heat exchanger 10 as a second heating means is newly installed in the vicinity of the auxiliary refrigerant pipe introduced into the injection port 16, and the internal heat exchanger 5 and the blower heat are installed. The refrigerant injected into the compressor 1 from the injection port 16 is heated using two types of heating means with the exchanger 10.

  For this reason, it becomes easy to add the superheat degree SH to the HFO refrigerant flowing through the auxiliary refrigerant pipe introduced into the injection port 16, and compared with the first embodiment, the discharge temperature on the outlet side of the compressor is prevented from being lowered. In addition, a more efficient hot water supply / heating refrigeration cycle can be realized.

  Further, in the second embodiment, in addition to using two types of heating means, a fan is attached to the blower heat exchanger 10 as the second heating means, and the rotation speed is controlled by an inverter. For this reason, it is possible to obtain a sufficient amount of heat exchange while designing the heat exchanger in a compact manner, and it is possible to stably supply superheated refrigerant at a desired temperature from the injection port 16 of the compressor. In the second embodiment, the states h and j are shifted to the high enthalpy region side (right side) as compared with the PH diagram of the first embodiment.

  Further, in the refrigeration cycle according to the second embodiment, the fan installation can be omitted by increasing the heat exchanger area of the blower heat exchanger 10.

Further, the exhaust heat of the control panel may be used as a heat source in addition to the blower heat exchanger 10 (see FIG. 7). In this case, an effect of adding a further superheat degree SH is expected.
As shown in FIG. 6, the control device 18 uses the pressure sensor 13 and the temperature sensor 14 to detect the refrigerant value detected by the second expansion device 8 and the blower heat exchange. The flow of control signals when controlling the instrument 10 is shown.

Embodiment 3 FIG.
In the vapor compression refrigeration cycle 300 showing the third embodiment of the present invention, the system configuration, the PH diagram, and the control flow are basically the same as those in the first embodiment, and are therefore omitted. 8 will be mainly described with reference to FIG.

  In the third embodiment, a circulating heat exchanger 11 as a second heating means is provided at the same position as the blower heat exchanger 10 of the second embodiment, and is replaced. In other words, in the vicinity of the sub refrigerant pipe introduced into the injection port 16, circulation heat exchange is a second heating means for exchanging heat with the liquid (air or brine) from which the exhaust heat of the compressor 1 is recovered. The heater 11 and the pump 12 are newly installed to heat the refrigerant injected into the compressor 1 from the injection port 16 using two types of heating means, that is, the internal heat exchanger 5 and the circulation heat exchanger 11. carry out.

  Here, the circulation heat exchanger 11 heats the refrigerant flowing through the sub refrigerant pipe using the liquid (air or brine) recovered from the exhaust heat of the compressor 1 in the vicinity of the sub refrigerant pipe. The pump 12 is disposed in the middle of a pipe connecting the compressor 1 and the circulation heat exchanger 11, and circulates liquid (air or brine) recovered from the exhaust heat of the compressor 1.

  For this reason, it becomes easy to add the superheat degree SH to the HFO refrigerant flowing through the auxiliary refrigerant pipe introduced into the injection port 16, and compared with the first embodiment, the discharge temperature on the outlet side of the compressor is prevented from being lowered. In addition, a more efficient hot water supply / heating refrigeration cycle can be realized. In the third embodiment, the states h and j are shifted to the high enthalpy region side (right side) as compared with the PH diagram of the first embodiment.

In the above, as a modified example of the third embodiment, the injection circuit 9 is directly wound around the compressor 1 to perform heat exchange, whereby the circulation heat exchanger 11 and the pump 12 and the accompanying heat (water or brine) are attached. The liquid circuit consisting of can also be omitted. Here, the modification of the third embodiment is a liquid-type winding type, but the heat source is still a liquid-type heating type.
As shown in FIG. 9, the control device 18 uses the second expansion device 8 and the circulation heat exchange based on the detected values of the refrigerant detected by the pressure sensor 13 and the temperature sensor 14. The flow of control signals when controlling the vessel 11 and the pump 12 is shown.

Embodiment 4 FIG.
In the vapor compression refrigeration cycle 500 showing the fourth embodiment of the present invention, the system configuration, the PH diagram, and the control flow are basically the same as those in the first embodiment, and are therefore omitted. 10 will be mainly described with reference to FIG.

  In the fourth embodiment, the gas portion (gas refrigerant) in the gas phase which has become the heating vapor among the refrigerant in the gas-liquid two-phase flow state stored in the receiver 4 is second from the upper portion of the receiver 4. This gas refrigerant output path is added so as to flow into the input side of the expansion device 8, thereby improving the heat exchange efficiency in the internal heat exchanger 5 as a single heating means.

  Regarding the configuration of the fourth embodiment, the difference from the first to third embodiments in the configuration is that an additional output path for the gas refrigerant is additionally provided in the upper part of the liquid receiver 4. One end of the refrigerant pipe is in contact with the liquid surface near the upper part of the receiver 4, and the other end is connected to the input side of the second expansion device 8. Of the refrigerant in the gas-liquid two-phase flow state stored in the liquid receiver 4, the gas portion in the gas phase that has become heated steam flows into the input side of the second expansion device 8, and the second The liquid part flows into the lower inlet of the internal heat exchanger 5 through the expansion device 8. Thereafter, heat is exchanged between the refrigerant flowing through the sub refrigerant pipe and the refrigerant flowing through the main refrigerant pipe inside the internal heat exchanger 5.

  For this reason, in the internal heat exchanger 5, it becomes easy to add the superheat degree SH to the HFO refrigerant flowing through the sub refrigerant pipe introduced into the injection port 16, and compared with the first embodiment, at the compressor outlet side. The discharge temperature can be prevented from decreasing, and a more efficient hot water supply / heating refrigeration cycle can be realized. In the fourth embodiment, the states h and j are shifted to the high enthalpy region side (right side) as compared with the PH diagrams of the first to third embodiments.

  As described above, in the present invention, even when an HFO refrigerant that tends to lower the discharge temperature is used, the temperature of the refrigerant that is intermediately injected into the compressor is maintained in an appropriate overheated state, and the discharge temperature at the outlet of the compressor. Can be prevented, and as a result, the operating efficiency (COP) of the refrigeration cycle can be improved.

  By the way, although the example which connected one condenser 3 and one evaporator 7 was used in the above-mentioned explanation, a plurality of condensers and evaporators may be connected.

  In the above description, the example using the heating operation is described, but it goes without saying that the same effect can be obtained even when this is replaced with the cooling operation. This system is an example, and the present invention is not limited to this system configuration.

  Further, the vapor compression refrigeration cycle of the present invention may be applied not only to the hot water supply utilization field but also to other fields.

  Needless to say, the techniques disclosed in the embodiments may be appropriately combined without departing from the gist of the present invention.

1 compressor, 2 four-way valve, 3 condenser, 4 receiver, 5 internal heat exchanger, 6 first expansion device, 7 evaporator, 8 second expansion device, 9 injection circuit, 10 blower type heat exchange , 11 Circulating heat exchanger, 12 Pump, 13 Pressure sensor, 14 Temperature sensor, 15 Outside air temperature sensor, 16 Injection port, 17 Temperature sensor, 18 Controller, 100, 200, 300, 400, 500 Vapor compression refrigeration cycle

Claims (5)

A vapor compression refrigeration cycle using HFO as a refrigerant,
The vapor compression refrigeration cycle is
A compressor provided with an injection port for injecting refrigerant circulating in the vapor compression refrigeration cycle;
A pressure sensor and a temperature sensor for measuring the pressure and temperature close to the injection port;
An expansion device that opens and closes the refrigerant so as to compress and expand;
A control device for controlling the opening degree of the expansion device based on the pressure and temperature obtained by the pressure sensor and the temperature sensor,
In the control device, the portion corresponding to the compression step in the PH diagram relating to the vapor compression refrigeration cycle is located outside the saturation curve composed of the saturated liquid line and the saturated vapor line, and from the critical pressure. Is located on the lower enthalpy region side than the saturated vapor line and is supplied via the main refrigerant pipe, and is supplied via the sub refrigerant pipe connected to the injection port. The state in which the two refrigerants are mixed and heat averaged in the compressor is positioned on the higher enthalpy region side than the state in which the compressor compresses the refrigerant to an intermediate pressure inside the compressor. And a vapor compression refrigeration cycle, wherein the expansion device is controlled. A blower heat exchanger is provided in the vicinity of the refrigerant pipe introduced into the injection port,
The vapor compression refrigeration cycle according to claim 1, wherein the refrigerant injected from the injection port is heated using the blower heat exchanger. A circulation heat exchanger is provided in the vicinity of the refrigerant pipe introduced into the injection port,
2. The vapor compression refrigeration cycle according to claim 1, wherein the refrigerant injected from the injection port is heated using the circulation heat exchanger. A liquid receiver connected to the input side of the expansion device;
An output path for the gas refrigerant is added so that the gas part in the gas phase that has become the heating vapor flows into the input side of the expansion device among the gas-liquid two-phase flow state refrigerant stored in the receiver. The vapor compression refrigeration cycle according to any one of claims 1 to 3, wherein the vapor compression refrigeration cycle is performed. The control device includes:
Controlling the opening degree of the expansion device so that the refrigerant injected from the injection port is heated steam having a superheat degree of 20 ° C. or higher and a high / low pressure ratio inside the compressor of 0.35 or higher. The vapor compression refrigeration cycle according to any one of claims 1 to 4.

Images