JP2011232011A - Cooling machine and refrigeration cycle device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling machine and a refrigeration cycle device for improving performance of an evaporator by lowering a target SH, ensuring reliability, and preventing an increase in cost.SOLUTION: In the cooling machine 10 configuring the refrigeration cycle device by being connected with a compressor 3 and a condenser 4 by refrigerant pipes 7, 8, the cooling machine 10 includes an expansion valve 12 and the evaporator 13. The evaporator 13 has a distributor 14 for branching an inlet of the evaporator 13 into a plurality of paths 15a-15d, capillary tubes 16s-16d, a header 17 for collecting a plurality of evaporator path outlets 18a-18d of the evaporator 13, an evaporator outlet temperature sensor 12a, and an equivalent evaporation temperature detecting means 12b. The capillary tube 16a of one of the plurality of paths 15a-15d has flow channel resistance larger than those of the capillary tubes 16b-16c of the other paths, and an opening of the expansion valve 12 is controlled so that an evaporator superheating degree determined from the an evaporator outlet temperature detected by the evaporator outlet temperature sensor 12 and an evaporation temperature detected by the equivalent evaporation temperature detecting means 12b, reaches a predetermined target value.

Description

  The present invention relates to a cooler and a refrigeration cycle apparatus that controls the flow rate of refrigerant flowing through the cooler with an expansion valve and an expansion valve control means in the cooler.

  Conventional refrigeration and refrigeration applications, for example, refrigeration cycle devices such as separate showcases and separate coolers, form a circuit by connecting a compressor, a condenser, an expansion valve, and an evaporator in order by piping. A heat source machine composed of a condenser and a cooler composed of an expansion valve and an evaporator are distinguished. The heat source device and the cooler are connected by an extension pipe between the condenser outlet and the expansion valve inlet, and between the evaporator outlet and the compressor inlet, respectively. Here, the heat source device and the cooler are generally different manufacturers, rather than the same manufacturer. For this reason, mutual communication such as refrigerant information between the heat source device and the cooler cannot be expected, and information transmission is only a low-pressure change at the time of starting and stopping the cooler.

  In addition, the model selection of the heat source machine and the cooler is performed by a third party different from the heat source machine manufacturer and the cooler manufacturer, such as a design office and an equipment contractor. Furthermore, the specification of the expansion valve of the cooler is generally determined by the aforementioned third party, not by the cooler manufacturer.

  In order to realize performance and capability improvement in such a situation, it is difficult to improve the entire system in both hardware and software, and improvement for each component is realistic. Heat source equipment includes many components and refrigerant circuits such as compressors, injection circuits, economizer circuits, etc., but the cooling equipment is limited for improvement, such as the heat transfer performance of the evaporator, and the remaining expansion There is not much improvement in the valve. In addition, there is a strong demand for cost reduction from the market, and it is not a situation where much cost is required for performance improvement. Further, assuming that the degree of superheat of the evaporator (hereinafter referred to as SH) is set by a conventional method, it is necessary to cope with setting the setting SH as large as before.

  The expansion valve defines the flow rate of the refrigerant passing through the cooler, and a temperature type expansion valve or an electronic expansion valve with variable flow path resistance is often used. The adjustment of the opening degree of the expansion valve is to be controlled by SH, and SH is obtained by (evaporator outlet temperature) − (evaporation temperature). The evaporator outlet temperature is obtained by calculating the saturation temperature from the temperature sensor provided at the evaporator outlet, the evaporation temperature is obtained from the temperature sensor provided at the location where the two-phase refrigerant exists in the evaporator, or the pressure sensor detecting the evaporation pressure. .

  In refrigeration / refrigeration applications, to avoid the liquid back state at the compressor inlet and prioritize reliability, the above-mentioned third party who sets the operating state of the refrigeration cycle apparatus sets the target SH to a large extent to achieve control stability. A large margin is often secured. Since SH is set to be excessive, the superheated gas region is large in the evaporator, and even in a cooler that is not much to be improved, the evaporator performance deteriorates.

  In order to solve such a problem, a sensitivity adjusting member is provided and installed between the temperature sensing cylinder of the temperature type expansion valve that detects the evaporator outlet temperature and the evaporator outlet pipe that is the detection target. Thus, a method has been proposed in which control stability can be improved without cost and the target SH can be reduced to improve performance (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 10-231950 (page 3-4, FIG. 1)

In the technique described in Patent Document 1, the control stability of the temperature expansion valve is improved by providing a simple thermal resistor in a temperature sensing cylinder that is a temperature sensor. However, temperature detection is performed by bringing the temperature sensing cylinder and piping into contact with each other, and the control stability cannot be obtained as much as the original target in order to cope with the sensitivity that is the key to control stability by increasing the contact area. As a result, the target SH remains excessive.
The electronic expansion valve has no restriction on the target SH because of its structure, but the target SH needs to be a positive value, and the same can be said for the electronic expansion valve.

  The present invention has been made to solve the above-described problems, and its purpose is to lower the target SH to improve the evaporator performance, and to ensure the reliability and suppress the increase in cost. A cooler and a refrigeration cycle apparatus are provided.

The cooler according to the present invention is a cooler connected to a compressor and a condenser by a refrigerant pipe to constitute a refrigeration cycle apparatus. The cooler includes an expansion valve and an evaporator. The evaporator is an evaporator. A distributor for branching the inlet of the gas into a plurality of paths, a capillary tube, a header for collecting a plurality of evaporator path outlets of the evaporator, an evaporator outlet temperature sensor, and a means for detecting an evaporation temperature. Evaporation obtained from the evaporator outlet temperature detected by the evaporator outlet temperature sensor and the evaporation temperature detected by the evaporation temperature equivalent detection means The opening degree of the expansion valve is controlled so that the degree of superheat of the vessel becomes a predetermined target value.
Moreover, the refrigerating cycle apparatus which concerns on this invention comprises a refrigerating cycle by connecting a compressor and a condenser, and said either cooler with refrigerant | coolant piping.

  According to the present invention, even if the target value of the evaporator superheat degree of the expansion valve is set large in order to ensure control stability, the evaporator superheat degree as the whole evaporator can be reduced and the performance is improved. can do.

It is a refrigerant circuit figure of the refrigerating cycle device in Embodiment 1 of the present invention. It is a refrigerant circuit figure of the refrigerating cycle device in Embodiment 2 of the present invention. It is a refrigerant circuit figure of the refrigerating cycle device in Embodiment 3 of the present invention.

Embodiment 1 FIG.
FIG. 1 is a refrigerant circuit diagram of a refrigeration cycle apparatus according to Embodiment 1 of the present invention.
Reference numeral 1 denotes a refrigeration cycle apparatus, 2 a heat source machine, 10 a cooler, 7 a liquid extension pipe, and 8 a gas extension pipe, which are connected as shown in the figure. In the heat source device 2, 3 is a compressor, 4 is a condenser, 5 is a liquid reservoir, and 6 is an accumulator. In the cooler 10, 11 is an on-off valve, 12 is a temperature expansion valve provided with a control means, and 13 is a heat exchanger constituting an evaporator. In the temperature type expansion valve 12, 12a is a temperature sensing cylinder provided with a temperature detection function, 12b is a pressure equalizing pipe, and 12c is a diaphragm. In the evaporator 13, 14 is a distributor, 15a to 15d are a plurality of passes, 17 is a header, and in each of the passes 15a to 15d, 16a to 16d are balance capillaries, and 18a to 18d are evaporations of the passes 15a to 15d. This is a container path exit. 18 is an outlet of the evaporator after being aggregated by the header 17, 19 is an outlet of the cooler 10, and these are connected as shown in the figure.
In addition, the heat source device 2 and the cooler 10 are installed in a remote place, and the condenser 4 and the evaporator 13 have different atmospheric temperatures.

  Next, the operation of the refrigeration cycle apparatus configured as described above will be described. The refrigerant is compressed by the compressor 3 in the heat source unit 2 to become a high-temperature and high-pressure superheated gas, and the outside air is conveyed by a condenser fan (not shown) by the condenser 4 to exchange heat. It becomes a state close to. Next, it passes through the liquid reservoir 5 and the liquid extension pipe 7 and reaches the inside of the cooler 10. At this time, the on-off valve 11 is open, and the refrigerant that has passed through the temperature type expansion valve 12 is depressurized to be in a two-phase state with low dryness. In the evaporator 13, the internal air is conveyed by an evaporator fan (not shown) to exchange heat with the refrigerant, the internal air is cooled, and the refrigerant is in a low-pressure superheated gas or a two-phase state with high dryness. Become. Thereafter, the outlet 19 reaches the compressor 3 through the gas extension pipe 8 and the accumulator 6.

  The path in the evaporator 13 is branched into a plurality by the distributor 14 at the inlet, passes through the paths 15 a to 15 d of the evaporator 13, and the header 17 from the evaporator path outlets 18 a to 18 d of each path of the evaporator 13. To the evaporator outlet 18. The reason for branching in this way is to reduce the pressure loss of the evaporator 13. The balance capillaries 16a to 16d at the inlets of the paths 15a to 15d of the evaporator 13 may have different flow resistances in order to adjust the refrigerant flow rate of the paths 15a to 15d. It may not have.

  The cooler 10 is used by an end user for cooling purposes. The refrigeration cycle apparatus is operated so that the suction temperature of the cooler 10 is the internal temperature of the refrigerator storing the object to be cooled, and the internal temperature becomes a predetermined target value desired by the end user. If the internal temperature is smaller than a certain cut value, the on-off valve 11 is closed, and if the internal temperature is larger than a certain input value, the on-off valve 11 is opened. The inside temperature may be the blowout temperature of the cooler 10 or the average value of the suction temperature and the blowout temperature of the cooler 10.

  When the pressure in the path from the on-off valve 11 to the compressor 3 decreases and becomes equal to or lower than a set value set in a control unit (not shown), a pressure switch (not shown) is activated and the compressor 3 is stopped. The refrigerant corresponding to the pressure drop is stored in the liquid reservoir 5. After that, when the internal temperature rises, the on-off valve 11 is opened, the pressure in the path from the on-off valve 11 to the compressor 3 rises, and when it exceeds the target value, a pressure switch (not shown) is activated and the compressor 3 starts operation. To do. The accumulator 6 has a role of a transient buffer that improves the reliability by preventing the liquid refrigerant from entering the compressor 3 at the time of such start / stop and when the operation state changes transiently.

  Next, the operation of the temperature type expansion valve 12 will be described. The temperature sensing cylinder 12a is installed at the evaporator path outlet 18a of one path 15a of the evaporator 13 to detect the refrigerant temperature (in the following description, the temperature sensing cylinder 12a may be referred to as an evaporator outlet temperature sensor). . The pressure equalizing pipe 12b is connected to the evaporator outlet 18 after the header 17a where the evaporator path outlets 18a to 18d are aggregated. The temperature sensing cylinder 12a and the diaphragm 12c are connected by piping, and a refrigerant different from that in the refrigeration cycle is enclosed. And (the pressure in the diaphragm 12c determined by the temperature detected by the temperature sensing cylinder 12a) and (the pressure in the pressure equalizing pipe 12b related to the evaporation temperature) + (the force by the spring (not shown) in the temperature type expansion valve 12) The opening degree of the temperature type expansion valve 12 is determined by the size of ÷ (diaphragm pressure receiving area). The force by the spring described above is adjusted by a third party and corresponds to the target SH (in the following description, the pressure equalizing pipe 12b may be referred to as an evaporating temperature equivalent detecting means). When the SH mechanically calculated by the temperature sensing cylinder 12a and the pressure equalizing pipe 12b is larger than the target SH, the flow resistance of the temperature type expansion valve 12 decreases and the refrigerant circulation amount increases, thereby reducing SH. Approaches the target SH. Conversely, when SH is smaller than the target SH, the flow path resistance of the temperature type expansion valve 12 increases and the refrigerant circulation amount decreases, so that SH increases and approaches the target SH. Thus, the expansion valve control means is mechanically incorporated into the temperature expansion valve 12.

  Here, the balance capillary 16a corresponding to the path 15a of the evaporator 13 in which the temperature sensing cylinder 12a is installed has a capillary length so that the flow path resistance is larger than the balance capillaries 16b to 16d of the other paths. large. For this reason, the refrigerant circulation amount of the path 15a is smaller than the refrigerant circulation amount of the other paths 15b to 15d, and as a result, the SH at the evaporator path outlet 18a is larger than the SH at the other evaporator path outlets 18b to 18d. . Further, the SH at the evaporator path outlet 18a is larger than the SH at the evaporator outlet 18 at the concentrated portion.

As described above, since the capillary length of the balance capillary 16a in the path 15a of the evaporator 13 in which the temperature sensing cylinder 12a is installed is set larger than that of the other balance capillaries 16b to 16d, the temperature-type expansion valve 12 is controlled. A certain SH remains large as before, and the SH of the entire evaporator 13 can be reduced. For this reason, since control stability can be secured even if the evaporator SH is made small, the capacity expansion of the cooler 10 and the performance improvement of the refrigeration cycle apparatus can be realized.
Further, since only the capillary length of one balance capillary 16a is increased, the cost reduction effect is sufficiently large, and the temperature expansion valve 12 itself is not changed, so that the market distribution is good and the cost reduction effect can be obtained. it can.
Furthermore, since there is a correlation between the SH that is the control target of the temperature type expansion valve 12 and the SH of the entire evaporator 13, it can be easily set by a third party. In this case, if the correlation between the SH of the temperature type expansion valve 12 and the SH of the entire evaporator 13 is grasped in advance and a correlation table showing this relationship is prepared, the equipment supplier who adjusts the refrigeration cycle apparatus 1 If the SH of the temperature type expansion valve 12 is adjusted, the SH of the entire evaporator 13 to be desired can be performed.
Moreover, the conventional method is realizable by re-installing the temperature sensing cylinder 12a in the whole evaporator exit 18. FIG.

  In the above description, the heat source device 2 and the cooler 10 are one, but the same applies even when the heat source device 2 is connected in parallel and the cooler 10 is connected in parallel. An effect can be obtained. Further, although the capillary length is changed in order to change the flow path resistance of the balance capillary 16a, the inner diameter of the capillary may be changed. Further, the connection point of the pressure equalizing pipe 12b may be the evaporator path outlet 18a. Although the condenser 4 is assumed to be air-cooled, it may be water-cooled, and further, the condenser 4 may be installed at a location away from the heat source device 2.

Embodiment 2. FIG.
FIG. 2 is a refrigerant circuit diagram of the refrigeration cycle apparatus according to Embodiment 2 of the present invention. In addition, the same code | symbol is attached | subjected to the same part as Embodiment 1, and description is abbreviate | omitted.
20 is a high-low pressure heat exchanger, a high-pressure part is connected between the on-off valve 11 and the temperature type expansion valve 12, and the low-pressure part is an evaporator path outlet in an evaporator path 15a provided with a temperature sensing cylinder 12a. 18a and the header 17 are connected. The temperature sensitive cylinder 12 a is provided between the low pressure portion of the internal heat exchanger 20 and the header 17.

  Next, the operation will be described. The description of the same operation as that of Embodiment 1 is omitted. In the high-low pressure heat exchanger 20, heat exchange is performed between the high-pressure liquid refrigerant and the low-pressure refrigerant exiting the evaporator path outlet 18a to cool the high-pressure liquid refrigerant and heat the low-pressure refrigerant. For this reason, although the outlet SH of the evaporator path outlet 18a in which the temperature sensitive cylinder 12a is installed is small, the SH detected by the temperature type expansion valve 12 is large, and the entire evaporator SH is small.

As described above, since the refrigerant passing through the evaporator path 15a in which the temperature sensing cylinder 12a is installed is heated by the high / low pressure heat exchanger 20, SH that is the control target of the temperature expansion valve 12 remains large as before. Thus, the SH of the entire evaporator can be reduced. For this reason, control stability can be ensured even if the evaporator SH is made small, so that the capacity of the cooler 10 can be increased and the performance of the refrigeration cycle apparatus can be improved. Is big.
Further, the size of the high-low pressure heat exchanger 20 is more dominant in the low-pressure gas portion than in the high-pressure liquid portion from the viewpoint of pressure loss and heat transfer. Therefore, it is sufficient if there is a high / low pressure heat exchanger 20 corresponding to the refrigerant circulation amount in one pass, and the cost increase can be suppressed.

Embodiment 3 FIG.
FIG. 3 is a refrigerant circuit diagram of the refrigeration cycle apparatus according to Embodiment 3 of the present invention. In addition, the same number is attached | subjected to the part same as other embodiment, and description is abbreviate | omitted.
31 is an electronic expansion valve, 21 is a temperature sensor, 22 is a pressure sensor, and is provided at the outlet 19 of the cooler 10 or upstream thereof. Reference numeral 30 denotes an expansion valve arithmetic unit provided in the electronic expansion valve 31, which is electrically connected to the temperature sensor 21, pressure sensor 22, and electronic expansion valve 31. The high pressure portion of the high / low pressure heat exchanger 20 is connected between the on-off valve 11 and the electronic expansion valve 31, and the low pressure portion is connected between the entire evaporator outlet 18 and the position of the temperature sensor 21.

Next, the operation will be described. Note that description of the same operation as that of the other embodiments is omitted. In the expansion valve arithmetic unit 30, SH is calculated from SH = (detection value of the temperature sensor 21) − (saturation temperature obtained by calculating the detection value of the pressure sensor 22). If SH> target SH, the flow resistance of the electronic expansion valve 31 is decreased, and the refrigerant circulation amount is increased to approach the target SH. Conversely, if target SH> SH, the flow of the electronic expansion valve 31 is increased. The road resistance is increased and the refrigerant circulation amount is decreased to approach the target SH.
In the high-low pressure heat exchanger 20, the high-pressure liquid refrigerant and the low-pressure refrigerant exiting the evaporator outlet 18 are heat-exchanged, the high-pressure liquid refrigerant is cooled, and the low-pressure refrigerant is heated. For this reason, although SH at the evaporator outlet 18 is small, SH detected by the temperature sensor 21 is large.

  Note that there is a correlation between SH that is the control target of the electronic expansion valve 31 and SH at the evaporator outlet 18. If this correlation is grasped in advance and stored in the expansion valve arithmetic unit 30, the equipment supplier who adjusts the refrigeration cycle apparatus 1 only sets the target value of SH at the evaporator outlet 18, and then the expansion valve arithmetic unit. By controlling SH as a control target 30, SH at the evaporator outlet 18 can be realized.

  Since the present embodiment is configured as described above, the SH to be controlled by the electronic expansion valve 31 remains large as before, and the SH of the entire evaporator can be reduced. In addition, since the liquid refrigerant is cooled at the high pressure portion of the internal heat exchanger 20, the degree of dryness of the inlet of the evaporator 13 is reduced, so that the distribution of the paths 15 a to 15 d of the evaporator 13 is improved. Further, the low-pressure refrigerant is heated in the low-pressure part of the high-low pressure heat exchanger 20, and further, the performance of the evaporator 13 can be improved by making the outlet dryness of the evaporator 13 slightly wet. Since the machine oil does not stay, the reliability of the compressor 3 is improved.

  DESCRIPTION OF SYMBOLS 1 Refrigeration cycle apparatus, 2 Heat source machine, 3 Compressor, 4 Condenser, 5 Liquid reservoir, 6 Accumulator, 7 Liquid extension piping, 8 Gas extension piping, 10 Cooling machine, 11 On-off valve, 12 Temperature type expansion valve, 12a Sense Warm tube (evaporator outlet temperature sensor), 12b Pressure equalizing tube (evaporation temperature equivalent detection means), 12c Diaphragm, 13 Evaporator, 14 Distributor, 15a-15d Evaporator paths, 16a-16d Balance capillary, 17 Header, 18 outlet of evaporator, 18a-18d outlet of each path of evaporator, 19 outlet of cooler, 20 high / low pressure heat exchanger, 21 temperature sensor, 22 pressure sensor, 30 expansion valve arithmetic unit, 31 electronic expansion valve.

Claims (12)

In the cooler constituting the refrigeration cycle apparatus connected with the compressor and the condenser and the refrigerant pipe,
The cooler comprises an expansion valve and an evaporator,
The evaporator includes a distributor that branches the inlet of the evaporator into a plurality of paths, a capillary tube, a header that aggregates a plurality of evaporator path outlets of the evaporator, an evaporator outlet temperature sensor, and an evaporation temperature equivalent detection means Have
One capillary tube of the plurality of paths is formed with a larger flow resistance than the capillary tube of the other path,
The opening degree of the expansion valve is controlled so that the degree of superheat of the evaporator determined from the evaporator outlet temperature detected by the evaporator outlet temperature sensor and the evaporation temperature detected by the evaporation temperature equivalent detection means becomes a predetermined target value. Cooling machine characterized by doing. In the cooler constituting the refrigeration cycle apparatus connected with the compressor and the condenser and the refrigerant pipe,
The cooler comprises an expansion valve and an evaporator,
The evaporator includes a distributor that branches the inlet of the evaporator into a plurality of paths, a capillary tube, a header that aggregates a plurality of evaporator path outlets of the evaporator, an evaporator outlet temperature sensor, and an evaporation temperature equivalent detection means Have
A high-low pressure heat exchanger is provided in the cooler, a high-pressure portion of the high-low pressure heat exchanger is connected between the condenser and an expansion valve, and a low-pressure portion of the high-low pressure heat exchanger is connected to the evaporator and the header The evaporator outlet temperature sensor between the low pressure part of the high and low pressure heat exchanger and the header,
The opening degree of the expansion valve is controlled so that the degree of superheat of the evaporator determined from the evaporator outlet temperature detected by the evaporator outlet temperature sensor and the evaporation temperature detected by the evaporation temperature equivalent detection means becomes a predetermined target value. Cooling machine characterized by doing.   3. The cooler according to claim 1, wherein the predetermined target value is set so that a degree of superheat determined by an outlet temperature of the header becomes positive.   The cooler according to any one of claims 1 to 3, wherein the evaporator outlet temperature sensor is installed at an outlet portion of a header. In the cooler constituting the refrigeration cycle apparatus connected to the compressor and the condenser with the refrigerant pipe,
The cooler comprises an expansion valve and an evaporator,
The evaporator includes a distributor that branches the inlet of the evaporator into a plurality of paths, a capillary tube, a header that aggregates a plurality of evaporator path outlets of the evaporator, an evaporator outlet temperature sensor, an evaporation temperature equivalent detection means, And an expansion valve arithmetic unit,
A high and low pressure heat exchanger is provided in the cooler, a high pressure portion of the high and low pressure heat exchanger is connected between the condenser and an expansion valve, and a low pressure portion of the high and low pressure heat exchanger is connected to an evaporator outlet. Connected between the compressors, the evaporator outlet temperature sensor and the evaporator temperature equivalent sensor are connected between the low pressure part of the high-low pressure heat exchanger and the compressor,
The expansion valve arithmetic unit is configured so that an evaporator superheat degree obtained from an evaporator outlet temperature detected by the evaporator outlet temperature sensor and an evaporation temperature detected by an evaporation temperature equivalent detecting unit becomes a predetermined target value. A cooler that controls the opening of an expansion valve.   The cooler according to claim 5, wherein the predetermined target value is set so that a refrigerant at an outlet of the evaporator is substantially saturated gas.   The cooler according to claim 5 or 6, wherein the evaporator outlet temperature sensor is installed in the header and a low pressure part of the high and low pressure heat exchanger.   The said expansion valve is a temperature type expansion valve, The cooler in any one of Claims 1-7 characterized by the above-mentioned.   Create a correlation table that grasps in advance the correlation between the predetermined target value and the degree of superheat of the evaporator determined from the outlet temperature of the header or the refrigerant state of the outlet of the header, and the predetermined target value based on the correlation table The cooler according to claim 8, wherein:   The cooler according to claim 1, wherein the expansion valve is an electronic expansion valve whose opening degree can be electrically changed. The predetermined target value;
A correlation between the degree of superheat of the evaporator determined from the outlet temperature of the header or the refrigerant state at the outlet of the header is previously grasped and stored in the expansion valve arithmetic device, and a predetermined target value is determined by the expansion valve arithmetic device. The cooler according to claim 10, wherein:   A refrigeration cycle apparatus comprising a compressor and a condenser and the refrigerator according to any one of claims 1 to 11 connected by a refrigerant pipe to constitute a refrigeration cycle.

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