JP2017155944A - Refrigeration cycle device and hot water heating device including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refrigeration cycle device capable of improving heating capacity and efficiency by controlling into a proper refrigeration cycle state quickly, even in a low outside air temperature.SOLUTION: A refrigeration cycle device includes: a first temperature sensor 61 for detecting a refrigerant temperature at a bypass passage 3 outlet; a first pressure sensor 51 for detecting an intake refrigerant pressure of a compressor 21; a second temperature sensor 62 for detecting a discharge temperature of the compressor 21; and a control device 4. By controlling in such a manner that, when a refrigerant overheating degree at the bypass passage 3 outlet is large and a temperature rise value in predetermined time of a discharge refrigerant temperature of the compressor 21 becomes equal to or greater than a predetermined value, the opening of a main expansion valve 24 and a bypass expansion valve 31 is operated in a closing direction by a predetermined opening degree, an abnormal rise of the discharge temperature at the time when the refrigerant is started to circulate in the bypass passage 3 can be suppressed. Thus, even when the outside temperature is low, high operation efficiency and sufficient heating capacity can be acquired.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a refrigeration cycle apparatus that bypasses a part of refrigerant flowing out of a radiator and performs heat exchange between the mainstream refrigerant and the bypass refrigerant to supercool the mainstream refrigerant.

  Conventionally, this type of refrigeration cycle apparatus and hot water heating apparatus is provided with a supercooling heat exchanger on the downstream side of the radiator of the refrigerant circuit, and from the radiator by allowing the expanded refrigerant to flow into the supercooling heat exchanger. The refrigerant that has flowed out is supercooled (see, for example, Patent Document 1).

  FIG. 5 shows a conventional refrigeration cycle apparatus described in Patent Document 1. As shown in FIG.

  As shown in FIG. 5, the refrigeration cycle apparatus 100 includes a refrigerant circuit 110 that circulates a refrigerant and a bypass 120. The refrigerant circuit 110 is configured by connecting a compressor 111, a radiator 112, a supercooling heat exchanger 113, a main expansion valve 114, and an evaporator 115 in an annular shape by piping.

  The bypass 120 branches from the refrigerant circuit 110 between the supercooling heat exchanger 113 and the main expansion valve 114, and enters the refrigerant circuit 110 between the evaporator 115 and the compressor 111 via the supercooling heat exchanger 113. linked. The bypass passage 120 is provided with a bypass expansion valve 121 upstream of the supercooling heat exchanger 113.

  Further, the refrigeration cycle apparatus 100 includes a temperature sensor 141 that detects the temperature of the refrigerant discharged from the compressor 111 (compressor discharge pipe temperature) Td, and the temperature of the refrigerant that flows into the evaporator 115 (evaporator inlet temperature). A temperature sensor 142 for detecting Te, a temperature sensor 143 for detecting the temperature (bypass side inlet temperature) Tbi of the refrigerant flowing into the supercooling heat exchanger 113 in the bypass passage 120, and the supercooling heat exchanger 113 in the bypass passage 120 And a temperature sensor 144 for detecting the temperature (bypass side outlet temperature) Tbo of the refrigerant flowing out of the refrigerant.

  The target temperature Td (target) of the discharge pipe of the compressor is set from the evaporator inlet temperature Te detected by the temperature sensor 142, and the discharge pipe temperature Td detected by the temperature sensor 141 is set to the target temperature Td (target). ), The difference (Tbo−Tbi) between the main expansion valve controller that controls the main expansion valve 114 and the bypass side outlet temperature Tbo and the bypass side inlet temperature Tbi in the supercooling heat exchanger 113 is a predetermined value. It is comprised from the bypass expansion valve control part which controls the bypass expansion valve 121 so that it may become a target value.

Japanese Patent Laid-Open No. 10-68553

  However, in the conventional configuration, the bypass expansion valve 121 operates so as to control the temperature difference between the inlet side and the outlet side of the bypass passage 120, that is, the degree of superheat of the bypass passage 120 outlet. The state cannot be controlled to a wet state.

Therefore, when the bypass expansion valve 121 is opened at the time of heating operation at an extremely low temperature such as an outside air temperature of −20 ° C., the bypass passage 120 is changed until the refrigerant flow rate in the bypass passage 120 increases to an appropriate amount. The flowing refrigerant is heated extremely in the supercooling heat exchanger 113, the suction refrigerant state of the compressor 111 becomes excessively overheated, and the discharge temperature of the compressor 111 may rise abnormally.

  Therefore, since the bypass path 120 cannot be used at a cryogenic outside air temperature and the effect of improving the operation efficiency due to the use of the bypass path 120 cannot be obtained, the efficiency is low and sufficient heating capacity cannot be secured. Had.

  The present invention solves the above-mentioned conventional problems, and provides a refrigeration cycle apparatus capable of improving heating capacity and efficiency even at a low outside air temperature by quickly controlling to an appropriate refrigeration cycle state. With the goal.

  In order to solve the conventional problems, a refrigeration cycle apparatus of the present invention includes a compressor, a radiator, a supercooling heat exchanger, a main expansion means, a refrigerant circuit in which an evaporator is connected in an annular shape, and the radiator. Branched from the refrigerant circuit between the main expansion means, and connected to the compressor circuit of the compressor or the refrigerant circuit between the evaporator and the compressor via the supercooling heat exchanger The bypass passage, bypass expansion means provided on the upstream side of the supercooling heat exchanger in the bypass passage, a first temperature sensor for detecting the temperature of the refrigerant flowing out of the supercooling heat exchanger, A first saturation temperature detecting means for detecting a saturation temperature of the refrigerant sucked into the compressor; a second temperature sensor for detecting a temperature of the refrigerant discharged from the compressor; and a controller. The temperature detected by the temperature sensor is the first saturation. The main expansion means and the bypass expansion means when the temperature rise value in a predetermined time of the temperature detected by the second temperature sensor is higher than a predetermined value that is higher than the saturation temperature detected by the temperature detection means. The opening is operated in the closing direction.

  As a result, it is possible to detect that the refrigerant mass flow rate in the bypass passage is excessively small. In this case, by increasing the pressure reduction amount in the main expansion means and the bypass expansion means, the evaporation of the refrigerant in the low pressure side evaporator is promoted. The liquid refrigerant staying on the low pressure side moves to the high pressure side.

  Therefore, the refrigerant at the inlet of the bypass expansion means is in a liquid state, and the refrigerant mass flow rate to the bypass passage rapidly increases, so that the refrigerant at the outlet of the bypass passage is saturated in a short time. The rise can be suppressed.

  ADVANTAGE OF THE INVENTION According to this invention, the refrigerating-cycle apparatus which can improve a heating capability and efficiency also at low outdoor temperature can be provided by controlling to a suitable refrigerating-cycle state rapidly.

Schematic configuration diagram of a refrigeration cycle apparatus according to Embodiment 1 of the present invention. (A) The figure which shows the relationship between the opening degree of the main expansion means of the same refrigeration cycle apparatus, and discharge temperature (b) The figure which shows the relationship between the opening degree of the bypass expansion means of the same refrigeration cycle apparatus, and discharge temperature The figure which shows the flowchart of the operation control of the same refrigeration cycle apparatus The figure which shows the relationship between the operation time at the time of normal operation of the refrigeration cycle apparatus, and its state change Schematic configuration diagram of a conventional refrigeration cycle apparatus

A first invention includes a compressor, a radiator, a supercooling heat exchanger, a main expansion unit, a refrigerant circuit in which an evaporator is annularly connected, and a branch from the refrigerant circuit between the radiator and the main expansion unit A bypass path connected to the compressor chamber of the compressor or the refrigerant circuit between the evaporator and the compressor via the supercooling heat exchanger, and the excess of the bypass path. Bypass expansion means provided on the upstream side of the cooling heat exchanger, a first temperature sensor for detecting the temperature of the refrigerant flowing out of the supercooling heat exchanger, and detecting the saturation temperature of the refrigerant sucked into the compressor A first saturation temperature detecting means, a second temperature sensor for detecting a temperature of the refrigerant discharged from the compressor, and a control device, wherein the temperature detected by the first temperature sensor is the first temperature sensor. Higher than the saturation temperature detected by the saturation temperature detection means, The opening degree of the main expansion means and the bypass expansion means is operated in the closing direction when the temperature rise value at a predetermined time of the temperature detected by the second temperature sensor becomes a predetermined value or more. The refrigeration cycle apparatus.

  Thus, it can be determined that the refrigerant mass flow rate in the bypass passage is excessively small, and in this case, by increasing the pressure reduction amount in the main expansion means and the bypass expansion means, evaporation of the refrigerant in the low pressure side evaporator is promoted. The liquid refrigerant staying on the low pressure side moves to the high pressure side.

  Therefore, the refrigerant at the inlet of the bypass expansion means is in a liquid state, and the refrigerant mass flow rate to the bypass passage rapidly increases, so that the refrigerant at the outlet of the bypass passage is saturated in a short time. The rise can be suppressed.

  Therefore, even when the outside air temperature is extremely low such as −20 ° C., the effect of increasing the enthalpy difference in the evaporator by heat exchange between the mainstream refrigerant in the supercooling heat exchanger and the refrigerant flowing through the bypass, and high pressure The pressure loss reduction effect of the low-pressure side refrigerant path by bypassing the refrigerant from the side to the low-pressure side can be utilized, and higher operating efficiency and sufficient heating capacity can be obtained.

  The second invention is characterized in that, in the first invention, when the temperature increase value is larger than when the temperature rise value is small, the operation amount in the closing direction of the main expansion means and the bypass expansion means is large.

  As a result, the amount of operation of the main expansion means and the bypass expansion means according to the degree of shortage of the decompression amount is obtained, so that the refrigerant state at the inlet of the bypass expansion means is quickly liquefied even in a wide range of load conditions, and the bypass path can be shortened in a shorter time The refrigerant at the outlet can be controlled to be saturated.

  Therefore, excessive increase of the discharge temperature of the compressor with respect to the target can be reduced, and the controllability of the refrigeration cycle and the reliability of the compressor can be further improved.

  According to a third invention, in the first or second invention, a third temperature sensor that detects a temperature of the refrigerant flowing out of the radiator, and a second saturation temperature detection that detects a saturation temperature of the refrigerant flowing through the radiator. Means, a fourth temperature sensor for detecting the temperature of the utilization side heat medium flowing into the radiator, and a fifth temperature sensor for detecting the temperature of the utilization side heat medium flowing out of the radiator. The degree of supercooling, which is the temperature difference between the temperature detected by the third temperature sensor and the saturation temperature detected by the second saturation temperature detection means, is determined by the temperature detected by the fourth temperature sensor and the fifth temperature sensor. When the temperature difference between the detected temperature and the detected temperature becomes a predetermined temperature, the operation of the main expansion means and the bypass expansion means in the closing direction is terminated.

  As a result, when the degree of supercooling of the refrigerant at the outlet of the radiator exceeds an appropriate value, the closing operation of the main expansion means and the bypass expansion means is terminated. Reduction can be suppressed.

  Therefore, it is possible to prevent the operation in the refrigeration cycle having a low efficiency due to excessive throttling of the main expansion means and the bypass expansion means, so that energy efficiency can be further improved.

  A fourth invention is a hot water heating apparatus including the refrigeration cycle apparatus according to any one of the first to third inventions, and not only when the radiator is a refrigerant-to-air heat exchanger, but also to the refrigerant-to-water heat exchange. It can also be applied to the case of a vessel.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 shows a schematic configuration diagram of a refrigeration cycle apparatus and a hot water heating apparatus according to a first embodiment of the present invention.

  In FIG. 1, the refrigeration cycle apparatus 1 </ b> A includes a refrigerant circuit 2 that circulates refrigerant, a bypass 3, and a control device 4.

  As the refrigerant, for example, a non-azeotropic refrigerant mixture such as R407C, a pseudo-azeotropic refrigerant mixture such as R410A, or a single refrigerant such as R32 can be used.

  The refrigerant circuit 2 includes a compressor 21, a radiator 22, a supercooling heat exchanger 23, a main expansion valve (main expansion means) 24, and an evaporator 25 that are annularly connected by piping.

  In the present embodiment, a sub-accumulator 26 and a main accumulator 27 that perform gas-liquid separation are provided between the evaporator 25 and the compressor 21. The refrigerant circuit 2 is provided with a four-way valve 28 for switching between normal operation and defrosting operation.

  In the present embodiment, the refrigeration cycle apparatus 1A constitutes heating means of a hot water heating apparatus that uses hot water generated by the heating means for heating, and the radiator 22 exchanges heat between the refrigerant and water. It is a heat exchanger that heats water.

  Specifically, a supply pipe 71 and a recovery pipe 72 are connected to the radiator 22, water is supplied to the radiator 22 through the supply pipe 71, and water (hot water) heated by the radiator 22 is the recovery pipe 72. It has come to be collected through.

  The hot water collected by the collection pipe 72 is sent to a heater such as a radiator directly or via a hot water storage tank, and thereby heating is performed.

  In the present embodiment, the bypass passage 3 branches from the refrigerant circuit 2 between the supercooling heat exchanger 23 and the main expansion valve 24, and the evaporator 25 and the compressor 21 are connected via the supercooling heat exchanger 23. In between, it is connected to the refrigerant circuit 2 between the sub-accumulator 26 and the main accumulator 27.

  The bypass passage 3 is provided with a bypass expansion valve (bypass expansion means) 31 on the upstream side of the supercooling heat exchanger 23.

  In the refrigerant circuit 2, a first pressure sensor 51 that detects the pressure (intake pressure) Ps of the refrigerant sucked into the compressor 21 and a temperature (discharge temperature) Td of the refrigerant discharged from the compressor 21 are detected. The second temperature sensor 62 that detects the pressure (condensation pressure) Pc of the refrigerant flowing out of the radiator 22, and the temperature of the refrigerant (radiator outlet temperature) Tco that flows out of the radiator 22. And a third temperature sensor 63 is provided.

The bypass passage 3 is provided with a first temperature sensor 61 that detects the temperature (bypass passage outlet temperature) Tbo of the refrigerant flowing out of the supercooling heat exchanger 23.

  On the other hand, the supply pipe 71 has a fourth temperature sensor 64 that detects the temperature (incoming temperature) Twi of water flowing into the radiator 22, and the recovery pipe 72 has a temperature of water flowing out of the radiator 22 (outflow temperature). ) A fifth temperature sensor 65 for detecting Two is provided.

  The control device 4 is detected by the first pressure sensor 51, the second pressure sensor 52, the first temperature sensor 61, the second temperature sensor 62, the third temperature sensor 63, the fourth temperature sensor 64, and the fifth temperature sensor 65. Based on the detected value or the like, the rotational speed of the compressor 21, the switching of the four-way valve 28, and the opening degrees of the main expansion valve 24 and the bypass expansion valve 31 are operated.

  In the normal operation, the refrigerant discharged from the compressor 21 is sent to the radiator 22 through the four-way valve 28, and in the defrosting operation, the refrigerant discharged from the compressor 21 is sent through the four-way valve 28. It is sent to the evaporator 25. In FIG. 1, the direction of refrigerant flow during normal operation is indicated by arrows.

  First, the state change of the refrigerant in the normal operation of the refrigeration cycle apparatus 1A of the present embodiment will be described based on FIG.

  The high-pressure refrigerant discharged from the compressor 21 flows into the radiator 22 and radiates heat to the water passing through the radiator 22. The high-pressure refrigerant flowing out of the radiator 22 flows into the supercooling heat exchanger 23 and is supercooled by the low-pressure refrigerant decompressed by the bypass expansion valve 31. The high-pressure refrigerant that has flowed out of the supercooling heat exchanger 23 is distributed to the main expansion valve 24 side and the bypass expansion valve 31 side.

  The high-pressure refrigerant distributed to the main expansion valve 24 is decompressed and expanded by the main expansion valve 24 and then flows into the evaporator 25. Here, the low-pressure refrigerant flowing into the evaporator 25 absorbs heat from the air.

  On the other hand, the high-pressure refrigerant distributed to the bypass expansion valve 31 side is decompressed by the bypass expansion valve 31 and expanded, and then flows into the supercooling heat exchanger 23. The low-pressure refrigerant that has flowed into the supercooling heat exchanger 23 is heated by the high-pressure refrigerant that has flowed out of the radiator 22. Thereafter, the low-pressure refrigerant that has flowed out of the supercooling heat exchanger 23 merges with the low-pressure refrigerant that has flowed out of the evaporator 25, and is sucked into the compressor 21 again.

  In the configuration of the refrigeration cycle apparatus 1A according to the present embodiment, the pressure of the refrigerant sucked into the compressor 21 at the low outside air temperature decreases and the refrigerant circulation amount decreases, thereby reducing the heating capacity of the radiator 22. It is for preventing.

  In order to realize this, the enthalpy difference in the evaporator 25 is increased by supercooling, and the refrigerant having a small endothermic effect that flows through the low-pressure side portion of the refrigerant circuit 2 by flowing the refrigerant through the bypass passage 3 by the bypass passage 3. It is important to reduce the amount of phase refrigerant and thereby reduce the pressure loss at the low pressure side portion of the refrigerant circuit 2.

  If the pressure loss in the low pressure side portion of the refrigerant circuit 2 is reduced, the pressure of the refrigerant sucked into the compressor 21 is increased by that amount, and the specific volume is reduced, so that the refrigerant circulation amount is increased.

  Further, if the enthalpy difference in the evaporator 25 is increased, even if the mass flow rate of the refrigerant passing through the evaporator 25 is reduced by circulating the refrigerant through the bypass passage 3, the heat absorption amount in the evaporator 25 is secured. can do.

That is, if the degree of supercooling of the refrigerant and the mass flow rate of the refrigerant in the bypass passage 3 are maximized, the maximum heating capacity improvement effect of the radiator 22 and the coefficient of performance improvement effect of the refrigeration cycle apparatus 1A can be obtained.

  However, when the effect of flowing the refrigerant through the bypass passage 3 is utilized at an extremely low temperature such as -20 ° C. or when the load on the use side is small, until the flow rate of the refrigerant flowing through the bypass passage 3 becomes appropriate During this period, there is a problem that the discharge temperature of the compressor rises abnormally.

  Therefore, it is important to suppress the abnormal increase in the discharge temperature in order to utilize the performance improvement effect by circulating the refrigerant through the bypass passage 3 under a wide range of conditions and improve the efficiency of the device.

  Therefore, in the present embodiment, the control device 4 determines that the bypass passage outlet temperature Tbo is equal to or higher than a predetermined temperature Tm from the suction saturation temperature Ts calculated based on the suction pressure Ps during normal operation (particularly at the start of bypass). When the change amount Atd of the discharge temperature Td at a predetermined time is higher than the predetermined change amount Am, the main expansion valve 24 and the bypass expansion valve 31 are calculated based on the change amount Atd. The operation opening degree Otm and the opening degree corresponding to the bypass expansion valve operation opening degree Otb are operated in the closing direction.

  Further, the control device 4 calculates the degree of supercooling Sc calculated from the difference between the condensation saturation temperature Tc calculated based on the condensation pressure Pc and the radiator outlet temperature Tco, based on the difference between the outlet water temperature Two and the incoming water temperature Twi. The operation of the main expansion valve 24 and the bypass expansion valve 31 in the opening closing direction is terminated when the temperature difference Dw of the water becomes equal to or greater than the predetermined temperature difference Dm.

  Further, the control device 4 sets the predetermined opening for operating the opening of the main expansion valve 24 and the bypass expansion valve 31 in the closing direction, for example, as shown in FIG. Therefore, an excessive increase in the discharge temperature can be suppressed.

  Next, the control specifications during normal operation of the refrigeration cycle apparatus 1A of the present embodiment will be specifically described based on the flowchart shown in FIG.

  FIG. 4 is a diagram showing the relationship between the operation time and the state change during normal operation of the refrigeration cycle apparatus 1A of the present embodiment.

  First, the control device 4 includes a first pressure sensor 51, a second pressure sensor 52, a first temperature sensor 61, a second temperature sensor 62, a third temperature sensor 63, a fourth temperature sensor 64, and a fifth temperature sensor 65. The discharge temperature Td, the bypass outlet temperature Tbo, the radiator outlet temperature Tco, the incoming water temperature Twi, the outgoing water temperature Two, the suction pressure Ps, and the condensation pressure Pc are detected (step S1).

  Next, the suction saturation temperature Ts at the pressure of the refrigerant sucked into the compressor 21 is calculated from the suction pressure Ps detected by the pressure sensor 51 (step S2). The calculation of the suction saturation temperature Ts is performed using a refrigerant physical property formula.

  Then, the bypass passage outlet temperature Tbo and the suction saturation temperature Ts are compared, and it is determined whether Tbo is higher than Ts by a predetermined temperature Tm that is set in advance (step S3).

  If the bypass passage outlet temperature Tbo is not higher than the suction saturation temperature Ts by a predetermined temperature Tm or more (NO in step S3), it is determined that the refrigerant flow rate in the bypass passage 3 is appropriate, and the routine proceeds to normal control.

On the other hand, if the bypass passage outlet temperature Tbo is higher than the suction saturation temperature Ts by a predetermined temperature Tm or more (YES in step S3), it is determined that the refrigerant flow rate in the bypass passage 3 is insufficient, and then the second temperature. A discharge temperature change amount Atd is calculated from the discharge temperature Td detected by the sensor 62 (step S4).

  The calculation of the discharge temperature change amount Atd is obtained from the difference between the discharge temperature Td (n) detected this time and the discharge temperature Td (n−1) detected a predetermined time ago.

  Next, the control device 4 determines whether or not the calculated discharge temperature change amount Atd is greater than or equal to a predetermined change amount Am set in advance (step S5).

  If the discharge temperature change amount Atd is less than the predetermined change amount Am (NO in step S5), it is determined that the increase rate of the discharge temperature is slow and that there is no abnormal temperature increase, and the routine proceeds to normal control.

  On the other hand, if the discharge temperature change amount Atd is equal to or greater than the predetermined change amount Am (YES in step S5), it is determined that the discharge temperature rises rapidly and the discharge temperature may reach the upper limit value, and the process proceeds to step S6. Transition.

  In step S6, the water temperature difference Dw is calculated from the difference between the water temperature Two and the water temperature Twi.

  Then, the condensation saturation temperature Tc of the refrigerant at the radiator 22 outlet is calculated from the condensation pressure Pc detected by the second pressure sensor 52, and the supercooling degree Sc is calculated from the difference between the condensation saturation temperature Tc and the radiator outlet temperature Tco. Calculated (step S7).

  Thereafter, the control device 4 compares the degree of supercooling Sc with the water temperature difference Dw, and determines whether Sc is greater than Dw by a predetermined temperature difference Dm or more (step S8).

  When the degree of supercooling Sc is greater than the water temperature difference Dw by a predetermined temperature difference Dw or more (YES in step S8), the refrigerant state at the outlet of the radiator 22 is in the liquid state, and the liquid refrigerant does not stay on the low pressure side. Determine and shift to normal control.

  On the other hand, if the degree of supercooling Sc is not greater than the water temperature difference Dw by a predetermined temperature difference Dw or more (NO in step S8), the refrigerant at the outlet of the radiator 22 is not sufficiently supercooled, and the refrigerant stays on the low pressure side. The process proceeds to step S9.

  In step S9, the operation opening degree Otm of the main expansion valve 24 and the operation opening degree Otb of the bypass expansion valve 31 are respectively calculated from the calculated discharge temperature change amount Atd. The calculation method of each operation opening degree Otm and Otb may be set as a function of the discharge temperature change amount Atd, for example, Otm = fm (Atd), Otb = fb (Atd).

  Then, the opening degree Otm of the main expansion valve 24 is operated in the closing direction, and the opening degree Otb of the bypass expansion valve 31 is operated in the closing direction.

  That is, in the present embodiment, as shown in FIG. 4, the control device 4 has a large refrigerant superheat degree at the outlet of the bypass passage 3 and has a predetermined temperature rise value for a predetermined time of the refrigerant discharge temperature of the compressor 21. When the value exceeds the value, the opening degree of the main expansion valve 24 and the bypass expansion valve 31 is controlled so as to operate at a predetermined opening degree in the closing direction, and the predetermined opening degree increases as the temperature rise value at a predetermined time increases. It is set to be.

In this state, the opening degrees of the main expansion valve 24 and the bypass expansion valve 31 are operated in the closing direction, whereby the evaporation of the refrigerant in the evaporator 25 is promoted, and the low-pressure parts such as the sub-accumulator 26 and the main accumulator 27 The refrigerant staying in a low dryness state is moved to the high pressure side.

  As a result, the refrigerant at the outlet of the radiator 22 is liquefied, so that the refrigerant mass flow rate to the bypass passage 3 side is rapidly increased and the outlet refrigerant of the bypass passage 3 is controlled to be saturated, as shown in FIG. In addition, an abnormal increase in the discharge temperature of the compressor 21 can be suppressed.

  Therefore, even when the outside air temperature is extremely low such as −20 ° C., the effect of increasing the enthalpy difference in the evaporator 25 due to heat exchange between the mainstream refrigerant and the bypass refrigerant in the subcooling heat exchanger 23 by bypass, and the refrigerant The effect of reducing the pressure loss of the low-pressure side refrigerant path due to the bypass can be utilized, and higher operating efficiency and sufficient heating capacity can be obtained.

  Moreover, since the excessive raise of discharge temperature can be suppressed more, the controllability of a refrigerating cycle and the reliability of the compressor 21 can further be improved.

  Further, as shown in FIG. 4, in the control device 4, the refrigerant supercooling degree at the outlet of the radiator 22 is larger than the temperature difference between the water flowing out from the radiator 22 and the water flowing into the radiator 22 by a predetermined value or more. Sometimes, the opening degree of the main expansion valve 24 and the bypass expansion valve 31 is set so as to end the control for the predetermined opening degree operation in the closing direction.

  As a result, when the degree of supercooling of the refrigerant at the outlet of the radiator 22 exceeds an appropriate value, the closing operation of the main expansion valve 24 and the bypass expansion valve 31 is terminated. An abnormal drop in low pressure can be suppressed.

  Therefore, it is possible to prevent the operation in the refrigeration cycle having a low efficiency due to excessive throttling of the main expansion means and the bypass expansion means, so that energy efficiency can be further improved.

  That is, based on the flowchart shown in FIG. 3 of the present embodiment, the refrigerant at the outlet of the radiator 22 is liquefied in a short time by operating the refrigeration cycle apparatus 1A normally, and the refrigerant mass flow rate toward the bypass path 3 is increased. By rapidly increasing, the refrigerant state at the outlet of the bypass passage 3 is controlled to a saturated state in a short time as indicated by point a ″ in FIG. 4. Therefore, as shown in FIG. The rise can be suppressed.

  Furthermore, the appropriate value of the refrigerant supercooling degree at the outlet of the radiator 22 can be determined from the temperature difference between the water flowing out from the radiator 22 and the water flowing into the radiator 22, and before the decompression amount of the expansion valve becomes excessively large. Since the closing operation is completed, an abnormal increase in the discharge pressure and an abnormal decrease in the suction pressure can be suppressed.

  In FIG. 1, the first pressure sensor 51 is provided between the position where the bypass path 3 in the refrigerant circuit 2 is connected and the main accumulator 27, but the first pressure sensor 51 is connected to the evaporator 25 and the compressor 21. As long as it is between, it may be provided at any position in the refrigerant circuit 2. Alternatively, the pressure sensor 51 may be provided on the downstream side of the subcooling heat exchanger 23 in the bypass passage 3.

  Further, in the present embodiment, the suction saturation temperature is calculated by the first pressure sensor 51, but the suction saturation temperature detects the temperature of the portion where the low-pressure two-phase refrigerant flows in the refrigerant circuit 2 and the bypass passage 3. It may be substituted.

Further, the bypass passage 3 is not necessarily branched from the refrigerant circuit 2 between the supercooling heat exchanger 23 and the main expansion valve 24, and the refrigerant circuit 2 is interposed between the radiator 22 and the supercooling heat exchanger 23. You may branch from.

  Moreover, the connection part of the bypass path 3 does not necessarily need to be the suction piping of the compressor 21, and in the case of a compressor having an injection mechanism, it may be connected to, for example, an injection port.

  In FIG. 1, the second pressure sensor 52 is provided between the radiator 22 and the supercooling heat exchanger 23 in the refrigerant circuit 2, but the second pressure sensor 52 is connected to the main expansion from the discharge pipe of the compressor. It may be provided at any position in the refrigerant circuit 2 as long as it is between the valves. When the pressure loss of the pipe is large, a value obtained by correcting the pressure loss may be used as the detection value.

  Furthermore, the main expansion means and bypass expansion means of the present invention are not necessarily expansion valves, and may be an expander that recovers power from the expanding refrigerant. In this case, for example, the rotational speed of the expander may be controlled by changing the load with a generator connected to the expander.

  INDUSTRIAL APPLICABILITY The present invention is particularly useful for a hot water heater that generates hot water using a refrigeration cycle apparatus and uses the hot water for heating.

DESCRIPTION OF SYMBOLS 1A Refrigeration cycle apparatus 2 Refrigerant circuit 3 Bypass path 4 Control apparatus 21 Compressor 22 Radiator 23 Supercooling heat exchanger 24 Main expansion valve (main expansion means)
25 Evaporator 31 Bypass expansion valve (Bypass expansion means)
51 1st pressure sensor (1st saturation temperature detection means)
52 Second pressure sensor (second saturation temperature detecting means)
61 1st temperature sensor 62 2nd temperature sensor 63 3rd temperature sensor 64 4th temperature sensor 65 5th temperature sensor

Claims (4)

A refrigerant circuit in which a compressor, a radiator, a supercooling heat exchanger, a main expansion unit, and an evaporator are connected in a ring shape; and the refrigerant circuit is branched between the radiator and the main expansion unit, and the supercooling heat Via a exchanger, a compression chamber of the compressor, or a bypass connected to the refrigerant circuit between the evaporator and the compressor;
Bypass expansion means provided on the upstream side of the subcooling heat exchanger in the bypass path;
A first temperature sensor for detecting the temperature of the refrigerant flowing out of the supercooling heat exchanger;
First saturation temperature detection means for detecting a saturation temperature of refrigerant sucked into the compressor;
A second temperature sensor for detecting the temperature of the refrigerant discharged from the compressor;
A control device;
With
The temperature detected by the first temperature sensor is higher than the saturation temperature detected by the first saturation temperature detecting means, and the temperature rise value at a predetermined time of the temperature detected by the second temperature sensor is a predetermined value. When it becomes above, the opening degree of the said main expansion means and the said bypass expansion means is operated in a closing direction, The refrigerating-cycle apparatus characterized by the above-mentioned. 2. The refrigeration cycle apparatus according to claim 1, wherein the amount of operation of the main expansion unit and the bypass expansion unit in the closing direction is larger when the temperature increase value is larger than when the temperature increase value is small. A third temperature sensor for detecting the temperature of the refrigerant flowing out of the radiator;
Second saturation temperature detection means for detecting the saturation temperature of the refrigerant flowing through the radiator;
A fourth temperature sensor for detecting the temperature of the use side heat medium flowing into the radiator;
A fifth temperature sensor for detecting the temperature of the use side heat medium flowing out of the radiator;
With
The degree of supercooling, which is the temperature difference between the temperature detected by the third temperature sensor and the saturation temperature detected by the second saturation temperature detecting means, is the temperature detected by the fourth temperature sensor and the fifth temperature. 2. The operation in the closing direction of the opening degree of the main expansion means and the bypass expansion means is terminated when a predetermined temperature becomes larger than a temperature difference with a temperature detected by a sensor. Or the refrigeration cycle apparatus of 2. The hot-water heating apparatus provided with the refrigeration cycle apparatus of any one of the said Claims 1-3.

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