JP4206870B2 - Refrigeration cycle equipment - Google Patents

Description

  The present invention relates to a refrigeration cycle apparatus having a plurality of condensers, and more particularly to a refrigeration cycle apparatus capable of adjusting both the temperature and humidity of supply air.

  As a conventional refrigeration cycle apparatus of this type, a refrigerant compressor, a first heat exchanger, a second heat exchanger, a refrigerant reheater, and a four-way valve are used, and a first electromagnetic valve is provided in a liquid pipe of the first heat exchanger. A four solenoid valve is provided in the gas pipe of the second heat exchanger, a second solenoid valve is provided in the liquid pipe of the second heat exchanger, and a third solenoid valve is provided in the gas pipe of the refrigerant reheater. Are connected to the third and fourth solenoid valves, the gas pipe of the first heat exchanger, the accumulator, and the refrigerant compressor, respectively, and the supply air passage sequentially passes through the first heat exchanger and the refrigerant reheater. It has become. And when using a 1st heat exchanger as an evaporator, a 1st solenoid valve is open | released and the refrigerant | coolant decompressed by the expansion device flows into a 1st heat exchanger.

  On the other hand, when heating supply air, a 1st heat exchanger is used as a condenser. The refrigerant condensed in the first heat exchanger passes through the check valve, passes through the opened second electromagnetic valve and expansion device, and flows into the second heat exchanger functioning as an evaporator. That is, the check valve is arranged to bypass any of the expansion devices when the refrigerant flow direction is reversed. The check valve provided on the pipe connected from the refrigerant reheater to the liquid pipe is arranged so that the refrigerant does not flow into the reheater when the first heat exchanger is used as a condenser. is there.

  In this conventional refrigeration cycle apparatus, the supply air can be heated in a mode in which the first heat exchanger is used as a condenser and the second heat exchanger as an evaporator, and the first heat exchanger is used as an evaporator, In the mode in which the heat exchanger is used as a condenser, the supply air can be cooled. Further, in the mode in which the first heat exchanger is used as an evaporator and the refrigerant reheater is used as a condenser, the supply air can be dried at room temperature. (For example, see Patent Document 1)

  Also, for example, with the same configuration as described above, the refrigerant can be circulated through both the second heat exchanger and the refrigerant reheater, the flow rate of each decompression means can be adjusted, and the flow rate ratio can be controlled. Some control the temperature of the supply air at the outlet of the reheater. (For example, see Patent Document 2)

JP 10-82585 A (page 2-3, FIG. 1) JP-A-5-340594 (page 3-4, Fig. 1-3)

  However, in the conventional configuration, since the reheater or the second heat exchanger is selected as the heat exchanger for condensing the refrigerant, the amount of heating in the reheater is determined by its size, and the supply air It is difficult to control the temperature and humidity at predetermined values.

  In the case where the reheater outlet temperature is adjusted to the target value by using the reheater and the second heat exchanger at the same time and controlling the refrigerant flow rate ratio, the reheater is used when the reheat amount is not required. Since a large amount of liquid refrigerant accumulates in the refrigerant circuit, a large amount of refrigerant is sealed in the refrigerant circuit, which not only increases the cost due to the increase in the size of the liquid receiver installed in the refrigeration cycle, but also when the compressor is started. The liquid back of the liquid causes deterioration of reliability.

  The present invention was made to solve the above problems, and by switching the operation mode according to the purpose, it is possible to adjust the temperature and humidity of the supply air to desired values, and An object is to obtain a refrigeration cycle apparatus that is low in cost and highly reliable with a constant amount of refrigerant regardless of the amount of reheat.

The refrigeration cycle apparatus of the present invention is a refrigeration cycle apparatus in which at least a compressor, a condenser, a decompression unit, and an evaporator are sequentially connected by piping, and a plurality of the condensers are arranged in parallel, and the outlet side of the condenser The pipe is provided with first pressure reducing means capable of adjusting the flow rate, and at least one of the condensers is disposed in the same air path as the evaporator, and a second pressure reducing means is provided in the inlet side pipe of the condenser. In the cooling and dehumidifying operation, the pressure P2 of the condenser disposed in the same air path as the evaporator and the pressure P1 of the condenser radiating heat to the outside air become different condensation pressures, and the target temperature of the supply air is reached. Based on this, the second pressure reducing means is controlled so that the heating amount becomes a predetermined value, and the refrigerant flows out of each condenser according to the operating frequency of the compressor so that the humidity of the supply air becomes the target value. Excessive refrigerant却度 in which controls the first pressure reducing means, respectively, as a constant value.

Further, in the refrigeration cycle apparatus of the present invention, when the amount of reheat is not required , the pressure P2 of the condenser disposed in the same air path as the evaporator and the pressure P1 of the condenser that radiates heat to the outside air are different. The second decompression means is controlled to be closed so that the condensation pressure is reached, the condenser side disposed in the same air path as the evaporator is opened, and the condenser side that radiates heat to the outside flows out. Each of the first pressure reducing means is controlled so that the degree of supercooling of the refrigerant to be maintained becomes a constant value.

Further, the refrigeration cycle apparatus of the present invention includes a four-way valve that switches a flow direction of the refrigerant discharged from the compressor, and is disposed in the same air path as the evaporator among the plurality of condensers during a heating operation. The heat exchanger that is not used functions as an evaporator.

  In the refrigeration cycle apparatus of the present invention, the evaporator includes an on-off valve that closes a part of the refrigerant flow path.

Further, the refrigeration cycle apparatus of the present invention is a refrigeration cycle apparatus in which at least a compressor, a condenser, a decompression unit, and an evaporator are sequentially connected by piping, and a plurality of the condensers are arranged in parallel, A first pressure reducing means capable of adjusting the flow rate is provided in each outlet side pipe, and at least one of the condensers is disposed in the same air path as the evaporator, and a second pipe is connected to the inlet side pipe of the condenser. of a pressure reducing means, among the plurality of condenser, the evaporator and at least one or more condensers of which does not equal the air passage, said compressor to divert part of the liquid refrigerant flowing out from the condenser The third depressurization means and the internal heat exchanger are provided in the branch circuit that circulates to the suction side, and in the cooling and dehumidification operation at low outside air, when the reheat amount is maximized, the second depressurization means is fully opened. the third pressure reducing means After decompression of a more diverted liquid refrigerant, the low-pressure side outlet temperature of the internal heat exchanger by heat exchange between the main flow of the liquid refrigerant is obtained by controlled so as to have a predetermined degree of superheat.

  Further, the refrigeration cycle apparatus of the present invention includes pressure detection means for detecting at least one of the discharge pressure and the suction pressure of the compressor so that the pressure value detected by the pressure detection means does not deviate from a predetermined range. And an evaporator heat exchange amount adjusting means for adjusting the heat exchange amount of the evaporator.

  In the refrigeration cycle apparatus of the present invention, the second pressure reducing means has a valve that can be driven by an electric motor, and adjusts the flow resistance by continuously changing the gap between the valve and the valve seat. It is.

  Further, in the refrigeration cycle apparatus of the present invention, the second decompression means includes a plurality of capillary tubes and open / close valves having different flow path resistances arranged in parallel, and the flow path resistance is adjusted stepwise by opening / closing the open / close valves. Is.

  In the refrigeration cycle apparatus of the present invention, the second pressure reducing means is an on-off valve that can be opened and closed at high speed.

According to the refrigeration cycle apparatus according to the present invention, in the refrigeration cycle apparatus in which at least a compressor, a condenser, a decompression unit, and an evaporator are sequentially connected by piping, a plurality of the condensers are arranged in parallel, and the condenser The outlet side piping is provided with a first pressure-reducing means capable of adjusting the flow rate, and at least one of the condensers is disposed in the same air path as the evaporator. During the cooling and dehumidifying operation, the pressure P2 of the condenser disposed in the same air passage as that of the evaporator and the pressure P1 of the condenser that radiates heat to the outside air have different condensation pressures. Each of the condensers is controlled in accordance with the operating frequency of the compressor such that the humidity of the supplied air becomes the target value while controlling the second pressure reducing means so that the heating amount becomes a predetermined value based on the target temperature. Spill from Since the degree of supercooling of the refrigerant to control the first pressure reducing means, respectively, as a constant value, it becomes possible to condense a different condensing pressure in each condenser, the water content of the air supplied to the target chamber After adjustment with the evaporator, the temperature can be adjusted with a condenser in the same air path, and the temperature and humidity of the supplied air can be controlled simultaneously.

Further, according to the refrigeration cycle apparatus of the present invention, when the reheat amount is unnecessary , the pressure P2 of the condenser disposed in the same air path as the evaporator and the pressure P1 of the condenser that radiates heat to the outside air The second decompression means is controlled to be closed so that the condensation pressures are different from each other, the condenser side disposed in the same air passage as the evaporator is open, and the condenser side radiates heat to the outside air since the degree of supercooling of the refrigerant flowing out to control the first pressure reducing means, respectively, as a constant value, it becomes possible to condense a different condensing pressure in each condenser, whereby the heat dissipation in the condenser Even when the temperature of the heat source to be changed is different, the ratio of the heat radiation amount can be arbitrarily adjusted, and the refrigerant amount is not biased and collected on one side.

Further, according to the refrigeration cycle apparatus of the present invention, a four-way valve that switches the flow direction of the refrigerant discharged from the compressor is provided, and is arranged in the same air path as the evaporator among the plurality of condensers during the heating operation. Since the heat exchanger that is not provided functions as an evaporator, the supply air can be heated and supplied to the target chamber.

  Further, according to the refrigeration cycle apparatus of the present invention, since the evaporator includes an on-off valve that closes a part of the refrigerant flow path, even when the outside air is at a high temperature of 35 ° C. or higher, the condensation pressure is Problems that rise abnormally and problems that the compressor input increases abnormally can be avoided.

Further, according to the refrigeration cycle apparatus of the present invention, in the refrigeration cycle apparatus in which at least a compressor, a condenser, a decompression unit, and an evaporator are sequentially connected by piping, a plurality of the condensers are arranged in parallel, and the condensation A first pressure-reducing means capable of adjusting the flow rate is provided in each outlet side pipe of the condenser, and at least one of the condensers is disposed in the same air path as the evaporator, and is connected to the inlet side pipe of the condenser. At least one of the second decompression means and the condenser that does not have the same air path as the evaporator among the plurality of condensers, a part of the liquid refrigerant flowing out from the condenser is shunted, A branch circuit that circulates to the suction side of the compressor is provided with a third decompression means and an internal heat exchanger, and in the cooling and dehumidification operation at the time of low outside air, when the maximum reheat amount is operated, the second decompression means is fully opened. as well as, the third reduction of After decompression of the liquid refrigerant diverted by means, since the low-pressure side outlet temperature of the internal heat exchanger by heat exchange between the main flow of the liquid refrigerant is controlled to be a predetermined degree of superheat, the outside air is 10 Even in the case of a low temperature of ℃ or less, it is possible to prevent a large amount of refrigerant from accumulating in a condenser whose air path is not the same as that of the evaporator, and two-phase refrigerant flows into a decompression means such as an electric expansion valve. It is possible to avoid problems caused by.

  The refrigeration cycle apparatus according to the present invention further includes pressure detection means for detecting at least one of the discharge pressure and the suction pressure of the compressor, and the pressure value detected by the pressure detection means is out of a predetermined range. Since the evaporator heat exchange amount adjusting means for adjusting the heat exchange amount of the evaporator is provided so that the evaporator is not frosted during low outside air. Furthermore, problems such as an abnormal increase in high pressure and an increase in abnormal compressor input can be avoided even during high outside air.

  Further, according to the refrigeration cycle apparatus of the present invention, the second pressure reducing means has a valve that can be driven by an electric motor, and the flow path resistance is adjusted by continuously changing the gap between the valve and the valve seat. Thus, the amount of heating in the reheater can be finely adjusted, and the accuracy of temperature control of the supply air is improved.

  Further, according to the refrigeration cycle apparatus of the present invention, the second decompression means includes a plurality of capillary tubes and open / close valves having different flow path resistances arranged in parallel, and the flow path resistance is gradually increased by opening / closing the open / close valves. Since the adjustment is performed, the equipment cost can be reduced.

  Further, according to the refrigeration cycle apparatus of the present invention, since the second pressure reducing means is an on-off valve that can be opened and closed at high speed, the cost can be further reduced.

Embodiment 1 FIG.
1 is a refrigerant circuit diagram showing the configuration of a refrigeration cycle apparatus according to Embodiment 1 of the present invention. In the figure, 1 is a compressor and 2 is a four-way valve. 3 is an outdoor heat exchanger, and the amount of heat exchange with the outside air can be adjusted by changing the number of rotations of the outdoor blower 4 that is provided in the vicinity of the outdoor heat exchanger 3 and blows outside air to the heat exchanger. . Reference numeral 5 denotes a reheater, which is connected to the outdoor heat exchanger 3 in parallel. In the outdoor heat exchanger 3 and the reheater 5, first decompression means (electric expansion valves) 6 and 7 that are throttle means are arranged in the liquid side pipes that are connected to the condensation outlets, respectively. In FIG. 5, the second decompression means 8 is also arranged in the gas side pipe on the condensation inlet side. Reference numeral 9 denotes a supply-side heat exchanger, which is disposed in the supply air passage 10 and exchanges heat with the air supplied by the supply blower 11. The reheater 5 is also arranged on the downstream side of the supply side heat exchanger 9 in the supply air passage 10 and exchanges heat with the air after heat exchange with the supply side heat exchanger 9. ing. In the refrigerant circuit diagram shown in FIG. 1, the refrigerant discharged from the compressor 1 passes through the four-way valve 2 (flow in the solid line direction in the figure) and enters the outdoor heat exchanger 3 or reheater 5 connected in parallel. After flowing in and exchanging heat, the pressure is reduced by passing through the first pressure reducing means (electric expansion valves) 6, 7, and then merges into one flow path and flows into the supply side heat exchanger 9. After the heat is exchanged by the supply side heat exchanger 9 and the heat is absorbed and absorbed, it is sucked into the compressor 1 through the four-way valve 2 and circulated. In the present embodiment, the supply blower 11 draws in outside air and adjusts the temperature and humidity of the air supplied to the target chamber so as to reach a target value.

  In the refrigeration cycle apparatus of the present embodiment configured as described above, the temperature and humidity of the air supplied to the air-conditioning target room can be freely adjusted, and the refrigerant amount distribution can be stably controlled. Hereinafter, the operation of this refrigeration cycle apparatus will be described in the order of cooling dehumidification operation and heating operation.

  First, the refrigeration cycle operation during the cooling and dehumidifying operation will be described with reference to FIG. 1 and FIG. FIG. 2 is a Ph diagram representing the refrigeration cycle operation during the cooling and dehumidifying operation, in which the vertical axis represents pressure [MPa] and the horizontal axis represents specific enthalpy [kJ / kg]. Note that points A to D in FIG. 2 correspond to positions A to D shown in the refrigerant circuit diagram of FIG. In FIG. 1, the four-way valve 2 forms a flow path in the solid line direction, and guides the high-temperature and high-pressure gas refrigerant (point A) discharged from the compressor 1 to both the outdoor heat exchanger 3 and the reheater 5 in parallel. . In the outdoor heat exchanger 3, when the refrigerant dissipates heat to the outside air and condensates, the rotational speed of the outdoor blower 4 is adjusted so that the condensation pressure in the outdoor heat exchanger 3 becomes a predetermined pressure value P1. Is done. The first pressure reducing means (electric expansion valve) 6 provided in the condensation outlet side pipe of the outdoor heat exchanger 3 has a degree of supercooling of the liquid refrigerant flowing out of the outdoor heat exchanger 3 of, for example, about 5 [deg]. The opening is adjusted to be

  In the reheater 5 connected in parallel with the outdoor heat exchanger 3, first, a gas refrigerant (decompressed to a certain pressure value P2 by the second decompression means 8 provided in the piping on the inlet side at the time of condensation) (B point) flows in and heat-exchanges with the cooled supply air SA1 mentioned later, and is condensed and liquefied. The condensation pressure value P2 on the reheater side at this time is adjusted by the second decompression means 8 so that the air heating amount in the reheater 5 becomes a predetermined value based on the target temperature of the supply air. The first pressure reducing means (electric expansion valve) 7 provided in the condensation outlet side pipe of the reheater 5 has a predetermined degree of supercooling degree of the refrigerant at the outlet of the reheater 5, similarly to the outdoor heat exchanger 3 side. For example, the opening degree is adjusted to be about 5 [deg].

  The liquid refrigerant that has flowed out of the outdoor heat exchanger 3 and the reheater 5 is decompressed by the first decompression means (electric expansion valves) 6 and 7 as described above, and is joined after the pressure value P3 is reached. It becomes a phase refrigerant (C point) and flows into the supply side heat exchanger 9. The supply side heat exchanger 9 exchanges heat with the outside air OA supplied from the supply blower 11, where the low-pressure two-phase refrigerant evaporates to become a gas refrigerant (point D), and again through the four-way valve 2. It is sucked into the compressor 1. In addition, the air SA1 cooled and dehumidified by passing through the supply side heat exchange 9 is guided to the supply air passage 10, passes through the reheater 5, and is reheated to become air SA2 having a target temperature. Supplied to the target room. At this time, the operating frequency of the compressor 1 is adjusted so that the moisture content of the supply air SA2 becomes the target value, and the humidity of the supply air SA2 is also adjusted to the target value.

  Here, the change of this supply air is demonstrated based on FIG. 1 and FIG. FIG. 3 is an air line diagram showing changes in supply air during the cooling and dehumidifying operation, in which the horizontal axis represents dry bulb temperature and the vertical axis represents absolute humidity. The refrigeration cycle apparatus of this embodiment adjusts the temperature and humidity of the supply air SA2 supplied to the air-conditioning target room to target values. The target values of the supply air SA2 are a temperature T2 [° C.] and a humidity X2. [kg / kg], the outside air OA which is the air of the supply source is To [° C.] and Xo [kg / kg]. First, the outside air OA is cooled and dehumidified to the state SA1 that has been cooled by passing through the supply-side heat exchanger 9. That is, the temperature decreases from To [° C.] to T1 [° C.], and the humidity decreases from Xo [kg / kg] to X2 [kg / kg]. At this time, the compressor 1 is controlled to an operating frequency commensurate with the cooling amount Δi [kJ / kg] required for cooling and dehumidification. Then, it passes through the reheater 5 and is heated from temperature T1 to temperature T2 [° C.]. CT2 [° C.] higher than the temperature T2 is a saturation temperature of the condensing pressure P2 in the reheater 5, and the condensing pressure P2 in the reheater is adjusted by the second decompression means 8 so that the supply air SA2 Is controlled to T2.

  As described above, in the present embodiment, the amount of reheat is adjusted by changing the condensation pressure P2 in the reheater while keeping the supercooling degree of the liquid refrigerant flowing out from the reheater 5 constant. Yes. Of course, even when the amount of reheat is not required at all, the second pressure reducing means (electric expansion valve capable of adjusting the flow rate) 8 is completely closed and the first pressure reducing means (electric expansion valve) 7 is opened. Thus, the reheater 5 communicates with the low pressure side, and liquid refrigerant does not accumulate. Therefore, the amount of liquid refrigerant staying in the reheater is almost unchanged regardless of the operating conditions, so that it is not necessary to install a liquid receiver for storing excess refrigerant in the refrigerant circuit, or the container can be made smaller. Furthermore, since the amount of the enclosed refrigerant can be reduced, problems such as liquid back at startup and transient high pressure rise can be reduced, and reliability is improved.

Next, the operation during the heating operation will be described with reference to FIG.
During the heating operation, the four-way valve 2 sets the refrigerant flow path in the direction of the broken line in the figure. The high-temperature and high-pressure gas refrigerant discharged from the compressor 1 flows into the supply-side heat exchanger 9 through the four-way valve 2 and exchanges heat with the outside air supplied from the supply blower 11 to be condensed and liquefied. At this time, the opening degree of the first decompression means (electric expansion valve) 6 is adjusted so that the outlet refrigerant supercooling degree of the supply side heat exchanger 9 is about 5 [deg]. On the other hand, the first pressure reducing means (electric expansion valve) 7 on the reheater side is closed, and there is no flow of refrigerant to the reheater 5. Then, the liquid refrigerant flowing out from the supply side heat exchanger 9 is decompressed by the first decompression means (electric expansion valve) 6, enters a low pressure two-phase state, and flows into the outdoor heat exchanger 3. Here, the outside air sent from the outdoor blower 4 absorbs heat and evaporates, and is sucked into the compressor 1 again via the four-way valve 2. Further, the supply air is heated by the supply side heat exchanger 9 and is supplied to the target chamber at a high temperature without changing the temperature in the reheater 5. The amount of heating at this time is adjusted by the operating frequency of the compressor 1.

Embodiment 2. FIG.
FIG. 4 is a refrigerant circuit diagram of a refrigeration cycle apparatus according to Embodiment 2 of the present invention. In the present embodiment, the purpose is to expand the operable range of high outside air conditions and low outside air conditions based on the refrigeration cycle apparatus shown in FIG. 1 described above. The same reference numerals are given to the same or corresponding parts as in FIG. 1, and the detailed description is omitted.

  In this embodiment, the supply-side heat exchanger is divided into 9a and 9b, and the solenoid valve 12 is arranged in the piping of one of the supply-side heat exchangers (9b in FIG. 4). Further, an internal heat exchanger 14 such as a double pipe is disposed between the outdoor heat exchanger 3 and the first pressure reducing means (electric expansion valve) 6. Low-pressure refrigerant branched from the main-stream high-pressure refrigerant and decompressed by a third decompression means (electric expansion valve) 13 that partially branches and decompresses the main stream flowing out of the outdoor heat exchanger 3 and flowing through the internal heat exchanger 14. Constitutes a branch circuit that exchanges heat with the main refrigerant and flows to the suction side of the compressor. A suction pressure sensor 15 for detecting the suction pressure is supplied to the suction side pipe of the compressor 1, a discharge pressure sensor 16 for detecting the discharge pressure is supplied to the discharge side pipe of the compressor 1, and a supply pipe is supplied to the connection pipe of the supply side heat exchanger 9. The control means 18 provided with the temperature sensor 17 which detects the refrigerant | coolant temperature in a side heat exchanger, and was connected so that communication with each of these sensors was carried out, The ventilation volume of the supply air blower 11 based on the detected pressure or temperature data, Alternatively, the heat transfer area of the supply side heat exchanger on the evaporator side can be adjusted by opening and closing the electromagnetic valve 12, and an evaporator heat exchange amount adjusting means is provided. Hereinafter, in this embodiment, the operation during the cooling and dehumidifying operation when the outside air is at a high temperature and when the outside air is at a low temperature will be described.

  When the outside air is at a high temperature, for example, 35 ° C. or more in the cooling and dehumidifying operation mode, the evaporation pressure in the supply side heat exchangers 9a and 9b that exchange heat with the outside air increases. Along with this, the density of the gas refrigerant sucked into the compressor 1 also increases, so that the refrigerant circulation amount increases. However, since the heat source that dissipates heat also in the outdoor heat exchanger 3 is high-temperature outside air, However, there is a possibility that the high pressure will rise abnormally due to insufficient condensing capacity.

  In the refrigeration cycle apparatus of this embodiment, the compressor discharge pressure and the suction pressure are always detected by the suction pressure sensor 15 and the discharge pressure sensor 16. When the discharge pressure or the suction pressure exceeds a preset upper limit value, the control means 18 sends a command to the supply blower 11 to reduce the air volume. In the supply-side heat exchangers 9a and 9b, the amount of heat exchange decreases due to a decrease in the amount of passing air, and the evaporation pressure decreases. As the evaporation pressure decreases, the refrigerant circulation rate also decreases, and the condensation pressure also decreases.

  Further, when the supply air volume is fixed to the required amount and the change is not allowed, the control means 18 closes the electromagnetic valve 12. Thereby, the heat transfer area of the supply side heat exchanger 9 decreases, and the evaporation pressure decreases. The subsequent state change is as described above. Here, although the supply side heat exchanger is divided into two parts 9a and 9b in the figure, it may be divided into three or more parts. By the operation as described above, an operation in which the discharge pressure exceeds the upper limit can be avoided, and the reliability of the refrigeration cycle apparatus can be improved.

  Subsequently, a case where the outside air is at a low temperature, for example, 10 ° C. or less will be described. When the outside air is at a low temperature, the evaporation temperature of the supply-side heat exchanger 9 becomes 0 ° C. or lower, and frost formation may occur. If frost formation occurs, the heat exchange is hindered and a defrosting operation is required. However, during the defrosting operation, the installation value that requires the temperature and humidity of the supply air is significantly deviated.

  Therefore, in the refrigeration cycle apparatus of this embodiment, the control means 18 calculates the evaporation temperature in the supply side heat exchanger 9 from the suction pressure detected by the suction pressure sensor 15, and the temperature is below 0 ° C. Sends a command to the supply blower 11 to reduce the air volume. The required cooling capacity for dehumidifying to the set water content is reduced due to the decrease in the supply-side blast volume, and the operation frequency of the compressor 1 is controlled to be reduced. As a result, the evaporation temperature rises and frost formation can be avoided. Here, the method of calculating the evaporation temperature from the suction pressure has been described. However, as shown in FIG. 4, the temperature sensor 17 is provided in the evaporation inlet side pipe of the supply side heat exchanger 9 serving as an evaporator to directly set the evaporation temperature. It may be detected. When R407C, which is a non-azeotropic refrigerant, is used as the refrigerant, the temperature at the evaporator inlet side pipe of the supply side heat exchanger 9 as shown in FIG. A sensor 17 is installed. In the case of other refrigerants, it is preferably installed in the middle of the evaporator.

  Another problem in the cooling and dehumidifying operation during low outside air is the refrigerant amount distribution when the reheater 5 is used. When operating at the maximum amount of reheat, the second decompression means 8 is fully opened, and the condensation pressure of the reheater 5 and the condensation pressure of the outdoor heat exchanger 3 are substantially equal, but the reheater 5 is a supply side heat exchanger. Heat exchange is performed with air having a temperature lower than that of the outside air cooled at 9, for example, 5 ° C. air, and the outdoor heat exchanger 3 performs heat exchange with the outside air, for example, 10 ° C. air. Therefore, if the refrigerant flow rate is such that the condensing temperature is 15 ° C., the reheater 5 has a temperature difference of 10 deg. Therefore, it is easy to set the degree of supercooling to 5 deg. If the refrigerant temperature does not coincide with the outside air temperature, the degree of supercooling does not reach 5 deg.

  In such a situation, the first pressure reducing means (electric expansion valve) 6 on the outdoor heat exchanger 3 side is narrowed, a lot of refrigerant flows through the reheater 5, and a small amount flows into the outdoor heat exchanger 3. Only the refrigerant flows, and a very long liquid portion is generated inside the refrigerant. That is, a large amount of liquid refrigerant accumulates in the outdoor heat exchanger 3. Further, in order to avoid this, if the first decompression means (electric expansion valve) 6 is inadvertently opened, the refrigerant passing through the first decompression means 6 becomes a two-phase state, which causes hunting or abnormal noise. There are concerns about the occurrence of defects.

  In the refrigeration cycle apparatus of this embodiment, an internal heat exchanger 14 is disposed on the condensation outlet side of the outdoor heat exchanger 3, and is configured to exchange heat with a decompressed liquid refrigerant flowing out of itself. . When it is determined that the difference between the outside air temperature and the condensation temperature is equal to or less than a predetermined value, the third pressure reducing means (electric expansion valve) 13 is configured such that, for example, the low-pressure side outlet temperature of the internal heat exchanger 14 has a predetermined superheat degree. The opening is adjusted. The refrigerant flowing out of the outdoor heat exchanger 3 as a condenser is cooled by the low-pressure two-phase refrigerant flowing through the low-pressure side of the internal heat exchanger 14, and has a predetermined degree of supercooling, for example, 5 degrees. It flows into the first pressure reducing means (electric expansion valve) 6. At this time, the high-pressure side inlet state of the internal heat exchanger 14 is slightly in a two-phase state.

  As described above, when the reheater 5 is used when the outside air is low, by ensuring the degree of supercooling with the internal heat exchanger 14, it is possible to avoid the accumulation of refrigerant in the outdoor heat exchanger 3 and the first It is possible to avoid problems due to the two-phase refrigerant flowing into the decompression means 6.

  Here, the configuration of the second decompression means 8 will be described. In the first embodiment and the second embodiment described above, a single flow rate adjusting valve is illustrated as having the same configuration as a normal electric expansion valve. The structure of the normal electric expansion valve is shown in FIG. 5, and the structure is such that the needle valve 31 is moved directly through the screw portion 35 by the electric motor using the coil 33 and the magnet 34, and the gap with the valve seat 32 is continuously formed. The flow path resistance is adjusted by changing to the above. By using such a flow rate adjusting means, the condensation pressure in the reheater can be continuously adjusted, and fine heating amount control can be realized.

  However, since the second pressure reducing means 8 is disposed at a portion where the gas refrigerant passes on the condensation inlet side, the pipe diameter is larger than that on the liquid side, and the same configuration as that of a normal electric expansion valve used as a flow rate adjusting means. Then, the valve size becomes very large, resulting in an increase in equipment cost. Therefore, for example, a configuration as shown in FIG. 6 can be considered.

  FIG. 6 is a block diagram showing another example of the second decompression means 8. The same reference numerals are given to the same or corresponding parts as in FIG. 1, and the detailed description is omitted. In the second pressure reducing means 8, a plurality of electromagnetic valves 21a, 21b, and 21c are connected in parallel, and capillary valves 22a and 22b having different flow path resistances are connected to the electromagnetic valves 21a and 21b, respectively.

  In such a configuration, for example, when the heating amount in the reheater 5 is unnecessary, all the solenoid valves 21a, 21b, and 21c are closed. When the heating amount is maximized, all the solenoid valves are opened. When the heating amount in the reheater 5 is controlled to a predetermined value, the solenoid valves 21a, 21b, and 21c are switched at any time so that the supply air temperature after passing through the reheater 5 approaches the set value. Adjust the condensing pressure in the reheater step by step. On the other hand, the opening of the first decompression means (electric expansion valve) 6 is controlled so that the degree of supercooling of the refrigerant at the outlet of the reheater 5 is always constant. In these configurations, the condensing pressure in the reheater can be controlled by several electromagnetic valves 21, so that it can be configured at a lower cost than an electric expansion valve using an electric motor.

  As another example of the second pressure reducing means, although not shown in the drawing, only one electromagnetic valve is arranged to repeatedly open and close the valve at high speed, and the flow rate is changed by changing the ratio between the opening time and the closing time. There is also a way to adjust.

  Further, as shown in the refrigerant circuit diagram of FIG. 7, the second decompression means 8 b may be provided also on the gas side that becomes the condensation inlet of the outdoor heat exchanger 3. For example, by having a mode that completely closes the flow rate adjusting valve that is the second decompression means 8b, all the heat of condensation of this refrigeration cycle can be processed only by the reheater 5, and the outside air is removed while dehumidifying. It is also possible to supply hotter air.

  In the first and second embodiments described above, one outdoor heat exchanger 3 and one reheater 5 each serving as a condenser are provided in the case of the solid line direction of the flow path switching by the four-way valve 4 in the figure. Although it demonstrated by the form, it is not restricted to this, For example, you may pipe-connect several outdoor heat exchangers in parallel, and the effect similar to the above is acquired. Further, even if a plurality of reheaters are connected in parallel and combined with the outdoor heat exchanger, the same effect can be obtained.

It is a refrigerant circuit figure of the refrigerating cycle device concerning Embodiment 1 of the present invention. FIG. 5 is a Ph diagram illustrating the refrigeration cycle operation during cooling and dehumidification according to the first embodiment of the present invention. It is an air line figure which concerns on Embodiment 1 of this invention and shows the change of the supply air at the time of cooling dehumidification. It is a refrigerant circuit figure of the refrigerating cycle device concerning Embodiment 2 of the present invention. It is a composition sectional view of the flow volume adjustment means concerning Embodiments 1 and 2 of the present invention. It is another block diagram of the flow volume adjustment means which concerns on Embodiment 1, 2 of this invention. It is a refrigerant circuit figure of another refrigeration cycle device concerning Embodiments 1 and 2 of the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Compressor, 2 Four-way valve, 3 Outdoor heat exchanger, 4 Outdoor fan, 5 Reheater, 6, 7 1st flow rate adjustment means, 8 2nd flow rate adjustment means, 9, 9a, 9b Supply side heat exchange , 10 supply air passage, 11 supply blower, 12 solenoid valve, 13 third flow rate adjusting means (electric expansion valve), 14 internal heat exchanger, 15 suction pressure sensor, 16 discharge pressure sensor, 17 temperature sensor, 18 control Means, 21a, 21b, 21c Solenoid valve, 22a, 22b Capillary tube, 31 Needle valve, 32 Valve seat, 33 Coil, 34 Magnet, 35 Screw part.

Claims (9)

In a refrigeration cycle apparatus in which at least a compressor, a condenser, a decompression unit, and an evaporator are connected in order by a pipe, a plurality of the condensers are arranged in parallel, and a flow rate can be adjusted to each outlet side pipe of the condenser. 1 decompression means, at least one of the condensers is disposed in the same air passage as the evaporator, and a second decompression means is provided in the inlet side piping of the condenser, and during the cooling and dehumidifying operation. The pressure P2 of the condenser disposed in the same air path as the evaporator and the pressure P1 of the condenser that radiates heat to the outside air become different condensation pressures, and the heating amount becomes a predetermined value based on the target temperature of the supply air The second depressurization means is controlled so that the supercooling degree of the refrigerant flowing out from each condenser is a constant value according to the operating frequency of the compressor such that the humidity of the supply air becomes the target value. So that Refrigerating cycle apparatus characterized by controlling the first pressure reducing means, respectively. When the amount of reheat is unnecessary , the second pressure P2 of the condenser disposed in the same air path as the evaporator and the pressure P1 of the condenser radiating heat to the outside air are different from each other. The decompression means is controlled to be in a closed state, the condenser side disposed in the same air path as the evaporator is open, and the condenser side that radiates heat to the outside air has a constant supercooling degree of the refrigerant flowing out. 2. The refrigeration cycle apparatus according to claim 1, wherein each of the first pressure reducing means is controlled so as to be. A four-way valve for switching the flow direction of the refrigerant discharged from the compressor is provided, and during heating operation , a heat exchanger that is not arranged in the same air path as the evaporator among the plurality of condensers functions as an evaporator The refrigeration cycle apparatus according to claim 1 or 2, wherein The refrigeration cycle apparatus according to any one of claims 1 to 3, wherein the evaporator includes an on-off valve that closes a part of the refrigerant flow path. In a refrigeration cycle apparatus in which at least a compressor, a condenser, a decompression unit, and an evaporator are connected in order by a pipe, a plurality of the condensers are arranged in parallel, and a flow rate can be adjusted to each outlet side pipe of the condenser. 1 decompression means, at least one of the condensers is disposed in the same air path as the evaporator, and a second decompression means and a plurality of the condensers are provided in an inlet side pipe of the condenser. Among them, at least one of the condensers that do not have the same air path as the evaporator has a branch circuit that divides a part of the liquid refrigerant flowing out of the condenser and distributes it to the suction side of the compressor. In the cooling and dehumidifying operation at the time of low outside air, when operating at the maximum reheat amount, the second decompressing means is fully opened and the current is divided by the third decompressing means. After depressurizing the liquid refrigerant, Serial refrigeration cycle apparatus low-pressure side outlet temperature of by heat exchange the internal heat exchanger is characterized by being controlled to a predetermined degree of superheat between the mainstream of the liquid refrigerant. Pressure detecting means for detecting at least one of the discharge pressure and suction pressure of the compressor is provided, and the heat exchange amount of the evaporator is adjusted so that the pressure value detected by the pressure detecting means does not deviate from a predetermined range. The refrigeration cycle apparatus according to any one of claims 1 to 5, further comprising an evaporator heat exchange amount adjusting means. The second pressure reducing means has a valve that can be driven by an electric motor, and adjusts the flow path resistance by continuously changing a gap between the valve and the valve seat. 6. The refrigeration cycle apparatus according to any one of 6. The second pressure reducing means includes a plurality of capillary tubes having different flow path resistances and a plurality of open / close valves arranged in parallel, and the flow path resistance is adjusted stepwise by opening / closing the open / close valves. Item 7. The refrigeration cycle apparatus according to any one of Items 6. The refrigeration cycle apparatus according to any one of claims 1 to 6, wherein the second decompression means is an on-off valve that can be opened and closed at high speed.

Images