Refrigeration equipment

Abstract

To provide a refrigeration system that suppresses the decrease in water temperature associated with defrosting. [Solution] The system comprises a plurality of upstream refrigeration cycles having upstream heat exchangers 50a on the user side, a plurality of downstream refrigeration cycles having downstream heat exchangers 50b on the user side, a flow path for a heat load medium connected in series in the order of upstream heat exchangers 50a and downstream heat exchangers 50b on the user side, and an operation mode control unit 350 that simultaneously defrosts the plurality of downstream refrigeration cycles and prevents the plurality of upstream refrigeration cycles from simultaneously defrosting.

Description

Technical Field

[0006] , , , , ,

[0001] The present invention relates to a refrigeration apparatus that performs a defrosting operation.

Background Art

[0002] When the refrigeration cycle is in a heating operation, if frosting occurs on the heat exchanger on the exhaust heat side, a decrease in heating capacity and a decrease in low-pressure pressure occur, resulting in a decrease in operating efficiency. In such a case, it is preferable to perform a defrosting operation of heating the heat exchanger on the exhaust heat side to remove the frost.

[0003] By the way, in the case of performing a defrosting operation in a chiller-type refrigeration cycle, a configuration for shortening the time during which the temperature of water decreases is known. For example, Japanese Patent No. 6410839 (Patent Document 1) discloses a configuration in which a plurality of refrigeration cycles are simultaneously subjected to a defrosting operation. According to Patent Document 1, the time during which the water temperature decreases can be shortened.

[0004] However, when all the refrigeration cycles are simultaneously subjected to a defrosting operation as in Patent Document 1, since the temperature of the warm water rapidly decreases, the comfort on the utilization side is impaired, and there is a possibility that the water may freeze. Therefore, in a chiller-type refrigeration apparatus having a plurality of refrigeration cycles, a technique for appropriately defrosting has been demanded.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] The present invention has been made in view of the problems in the above prior art, and an object thereof is to provide a refrigeration apparatus that suppresses a decrease in the water temperature accompanying defrosting.

Means for Solving the Problems

[0007] In other words, according to the present invention, Multiple upstream refrigeration cycles having upstream heat exchangers on the user side, Multiple downstream refrigeration cycles having downstream heat exchangers on the user side, The flow path of the heat load medium is connected in series in the order of the upstream heat exchanger on the user side and the downstream heat exchanger on the user side, Control means for simultaneously defrosting multiple downstream refrigeration cycles and preventing simultaneous defrosting of multiple upstream refrigeration cycles. A refrigeration system is provided that includes the following features. [Effects of the Invention]

[0008] According to the present invention, a refrigeration system can be provided that suppresses the decrease in water temperature associated with defrosting. [Brief explanation of the drawing]

[0009] [Figure 1] A diagram of the refrigeration cycle of the refrigeration system in this embodiment. [Figure 2] A diagram showing the hardware configuration included in the control board of this embodiment. [Figure 3] A software block diagram included in the refrigeration system of this embodiment. [Figure 4] A flowchart illustrating the processes performed by the refrigeration apparatus of this embodiment. [Figure 5] This diagram illustrates the positional relationship of the refrigeration cycle that performs heating and defrosting operations in this embodiment. [Figure 6] This diagram illustrates the positional relationship of the refrigeration cycle that performs heating and defrosting operations in this embodiment. [Figure 7] This figure illustrates an example of the positional relationship of a refrigeration cycle capable of defrosting operation in this embodiment. [Figure 8] This figure illustrates an example of the positional relationship of a refrigeration cycle capable of defrosting operation in this embodiment. [Figure 9] This figure illustrates an example of the positional relationship of a refrigeration cycle capable of defrosting operation in this embodiment. [Figure 10] A diagram for explaining an example of the positional relationship of a refrigeration cycle capable of defrosting operation in the present embodiment. [Figure 11] A diagram for explaining an example of the positional relationship of a refrigeration cycle capable of defrosting operation in the present embodiment. [Figure 12] A diagram for explaining an example of the positional relationship of a refrigeration cycle capable of defrosting operation in the present embodiment. <0OO0076>A diagram for explaining an example of the positional relationship of a refrigeration cycle capable of defrosting operation in the present embodiment. [Figure 14] A diagram for explaining an example of the positional relationship of a refrigeration cycle capable of defrosting operation in the present embodiment.

Embodiments for Carrying Out the Invention

[0010] Hereinafter, the present invention will be described with reference to embodiments, but the present invention is not limited to the embodiments described below. In each of the figures referred to below, the same reference numerals are used for common elements, and the description thereof will be omitted as appropriate.

[0011] First, the refrigeration cycle according to the present embodiment will be described with reference to FIG. 1. FIG. 1 is a system diagram of the refrigeration cycle of the refrigeration apparatus 1 in the present embodiment. The refrigeration apparatus 1 of the present embodiment is configured to include a plurality of refrigeration cycle units 10 (10a, 10b, 10c, 10d). The refrigeration cycle unit 10 performs heat exchange between air and a refrigerant. In the embodiment described below, the case where the number of refrigeration cycles constituting the refrigeration apparatus 1 is four is taken as an example, but the embodiment is not particularly limited. In FIG. 1, the detailed configuration of the refrigeration cycle unit 10a is typically illustrated, but the other refrigeration cycle units 10b, 10c, 10 also have the same configuration.

[0012]

[0012] は原文通り As shown in FIG. 1, the refrigeration cycle unit 10 is composed of various components such as a four-way valve 31, an accumulator 32, a compressor 33, an expansion device 34, an exhaust heat side heat exchanger 21, and a blower 22. The exhaust heat side heat exchanger 21 is referred to as an air side heat exchanger. Hereinafter, for convenience, among the various components constituting the refrigeration cycle unit, the components excluding the exhaust heat side heat exchanger 21 and the blower 22 are collectively referred to as "refrigeration cycle components 30".

[0013] Furthermore, the refrigeration device 1 of the present embodiment includes a utilization side heat exchanger 50 (50a, 50b) that performs heat exchange between water and a refrigerant, and is configured by connecting the refrigeration cycle unit 10 and the utilization side heat exchanger 50. The utilization side heat exchanger 50 is referred to as a water side heat exchanger. The exhaust heat side heat exchanger 21 and the blower 22 are housed in the heat exchanger chamber 20. Also, the refrigeration cycle components 30 and the utilization side heat exchanger 50 are housed in the machine room at the lower part of the heat exchanger chamber 20.

[0014] In the refrigeration cycle unit 10, the compressor 33, the four-way valve 31, the exhaust heat side heat exchanger 21, the expansion device 34, the utilization side heat exchanger 50, and the accumulator 32 are connected by a pipe r. The refrigerant enclosed in the refrigeration cycle flows through the compressor 33, the four-way valve 31, the exhaust heat side heat exchanger 21, the expansion device 34, the utilization side heat exchanger 50, and the accumulator 32 through the pipe r respectively. The solid line of the four-way valve 31 in FIG. 1 indicates the flow of the refrigerant during the cooling operation of the refrigeration device 1. By switching the four-way valve 31 to the connection side of the broken line, the heating operation is achieved.

[0015] The upstream heat exchanger 50a on the user side, connected to refrigeration cycle units 10a and 10d, and the downstream heat exchanger 50b on the user side, connected to refrigeration cycle units 10b and 10c, are connected in series by piping 40. The heat load medium responsible for heating and cooling flows through piping 40 from the upstream heat exchanger 50a on the user side to the downstream heat exchanger 50b on the user side. In the embodiment described, a heat load medium circuit is formed by multiple user-side heat exchangers 50 and piping 40 through which the heat load medium flows. In the following description, the direction of flow of the heat load medium is assumed to be from upstream to downstream, with the upstream heat exchanger 50a on the user side being referred to as the upstream side and the downstream heat exchanger 50b on the user side being referred to as the downstream side. Although Figure 1 illustrates a configuration in which two refrigeration cycle units 10 are connected to one user-side heat exchanger 50, this does not limit the embodiment, and the number of refrigeration cycle units 10 connected to the user-side heat exchanger 50 is not particularly limited. Furthermore, in the following explanation, the refrigeration cycle unit 10 and the user-side heat exchanger 50 may be referred to collectively as the "refrigeration cycle."

[0016] For example, water is used as the heat load medium, and low-temperature water is produced in the case of cooling and high-temperature water in the case of heating through heat exchange in the upstream heat exchanger 50a on the user side and the downstream heat exchanger 50b on the user side (in the following embodiments, the case in which water is used as the heat load medium is used as an example, but the embodiments are not particularly limited). The compressor 33 is composed of a scroll compressor, rotary compressor, etc., and is composed of a compressor with a variable operating capacity or a compressor with a fixed operating capacity. The upstream heat exchanger 50a on the user side and the downstream heat exchanger 50b on the user side are composed of a laminated plate type heat exchanger, a shell and tube type heat exchanger, a double-tube heat exchanger, etc. The accumulator 32 separates gas and liquid to prevent liquid from entering the compressor 33 and causing damage.

[0017] When the refrigeration system 1 is in cooling operation, the high-temperature, high-pressure gaseous refrigerant compressed by the compressor 33 in the refrigeration cycle unit 10 passes through the flow path on the solid line side of the four-way valve 31 in Figure 1. Then, it dissipates heat and condenses in the heat exchanger 21 on the exhaust side, becoming a liquid refrigerant at room temperature and high pressure. This liquid refrigerant at room temperature and high pressure is then depressurized by the expansion device 34 to become a low-temperature, low-pressure liquid refrigerant. In the heat exchanger 50 on the utilization side, it exchanges heat with the heat load medium supplied from the piping 40, evaporates, and returns to the compressor 33 as a low-temperature, low-pressure gaseous refrigerant. In the heat exchanger 50 on the utilization side, the low-temperature, low-pressure liquid refrigerant absorbs heat from the heat load medium due to the latent heat of vaporization during the evaporation of the liquid refrigerant, thus cooling the heat load medium.

[0018] Furthermore, when the refrigeration unit 1 is operating in heating mode, the high-temperature, high-pressure gaseous refrigerant compressed by the compressor 33 in the refrigeration cycle unit 10 passes through the flow path on the dashed line side of the four-way valve 31 in Figure 1. There, it exchanges heat with the heat load medium in the utilization-side heat exchanger 50, releases heat, and condenses to become a room-temperature, high-pressure liquid refrigerant. In the utilization-side heat exchanger 50, the heat load medium is heated by the heat of condensation of the high-temperature, high-pressure gaseous refrigerant. The room-temperature, high-pressure liquid refrigerant is then depressurized by the expansion device 34 to become a low-temperature, low-pressure liquid refrigerant. The low-temperature, low-pressure liquid refrigerant is evaporated by the heat exhaust-side heat exchanger 21 to become a low-temperature, low-pressure gaseous refrigerant and returns to the compressor 33.

[0019] As shown in Figure 1, the refrigeration system 1 of this embodiment is configured to include a control board 60 for controlling the operation of each refrigeration cycle. The control board 60 can control the operation of the blower 22 and the refrigeration cycle components 30.

[0020] Next, the hardware configuration of the control board 60 will be described. Figure 2 shows the hardware configuration included in the control board 60 of this embodiment. The control board 60 of this embodiment is composed of a CPU 61, RAM 62, ROM 63, sensor I / F 64, and refrigeration cycle I / F 65, and each piece of hardware is connected via a bus.

[0021] The CPU 61 is a device that executes a program to control the operation of the refrigeration device 1 and performs predetermined processing. The RAM 62 is a volatile memory device that provides the execution space for the program executed by the CPU 61 and is used for storing and retrieving programs and data. The ROM 63 is a non-volatile memory device that stores programs and firmware executed by the CPU 61.

[0022] Sensor I / F64 is an interface for connecting to sensors that detect various information regarding the operation of the refrigeration system 1. Examples of sensors connected to Sensor I / F64 include a refrigerant temperature sensor, a refrigerant pressure sensor, an indoor temperature sensor, an outdoor temperature sensor, and a humidity sensor, but the embodiment is not particularly limited.

[0023] The refrigeration cycle I / F65 is an interface for controlling the operation of various components that make up the refrigeration cycle shown in Figure 1. As shown in Figure 1, the refrigeration cycle I / F65 of this embodiment can be connected to various refrigeration cycle components 30, such as a blower 22, a four-way valve 31, an accumulator 32, a compressor 33, and an expansion device 34.

[0024] The hardware configuration included in the control board 60 of this embodiment has been described above. Next, the functional means executed by each piece of hardware in this embodiment will be described with reference to Figure 3. Figure 3 is a software block diagram included in the refrigeration device 1 of this embodiment.

[0025] As shown in Figure 3, the refrigeration system 1 of this embodiment is configured to include the following functional means: a temperature measuring unit 310, a pressure measuring unit 320, a frost detection unit 330, a defrost feasibility determination unit 340, and an operation mode control unit 350. The details of each functional means will be described below.

[0026] The temperature measuring unit 310 is a means for measuring various temperatures related to the refrigeration device 1. The temperature measuring unit 310 constitutes the measuring means in this embodiment. In this embodiment, the temperature measuring unit 310 can measure temperature by acquiring values ​​measured by various sensors via the sensor I / F 64. The temperature measuring unit 310 can measure, for example, room temperature, ambient temperature, refrigerant temperature, etc.

[0027] The pressure measuring unit 320 is a means for measuring the pressure of the refrigerant circulating in the refrigeration cycle. The pressure measuring unit 320 constitutes the measuring means in this embodiment. The pressure measuring unit 320 in this embodiment can measure, for example, the pressure of the refrigerant drawn into the compressor 33 or the pressure of the refrigerant discharged from the compressor 33.

[0028] The frost detection unit 330 is a means for detecting the presence or absence of frost on the exhaust heat exchanger 21. The frost detection unit 330 constitutes the detection means in this embodiment. The frost detection unit 330 in this embodiment can detect the presence or absence of frost based on the temperature and pressure values ​​measured by the temperature measurement unit 310 and the pressure measurement unit 320. For example, when frost forms on the exhaust heat exchanger 21, heat exchange becomes more difficult, and the difference between the ambient temperature and the evaporation temperature of the refrigerant increases. Therefore, when the temperature difference exceeds a predetermined threshold, the frost detection unit 330 can detect that there is frost on the exhaust heat exchanger 21. Furthermore, as frost progresses, heat exchange becomes even more difficult, causing the suction pressure (low pressure) of the compressor 33 to decrease. Therefore, when the suction pressure falls below a predetermined threshold, the frost detection unit 330 can detect that the exhaust heat exchanger 21 is in a state of excessive frosting.

[0029] The defrost feasibility determination unit 340 is a means for determining whether or not a defrost operation can be performed on the exhaust heat exchanger 21 in which frost has been detected. The defrost feasibility determination unit 340 constitutes the determination means in this embodiment. The defrost feasibility determination unit 340 in this embodiment can determine whether or not a defrost operation can be performed based on whether the positional relationship between the refrigeration cycle including the exhaust heat exchanger 21 in which frost has not been detected (i.e., the refrigeration cycle that performs heating operation) and the refrigeration cycle including the exhaust heat exchanger 21 in which frost has been detected (i.e., the refrigeration cycle that is the target of the defrost operation) satisfies predetermined conditions. For example, if the positional relationship between the refrigeration cycle that performs heating operation and the refrigeration cycle that is the target of the defrost operation is such that the temperature of the heat load medium (e.g., water) would become too low if a defrost operation were performed, the defrost feasibility determination unit 340 in this embodiment will determine that a defrost operation should not be performed. Details of the conditions for the positional relationship between the refrigeration cycle that performs heating operation and the refrigeration cycle that is the target of the defrost operation will be described later.

[0030] The operating mode control unit 350 is a means for controlling the operating mode of the refrigeration cycle that constitutes the refrigeration system 1 of this embodiment. The operating mode control unit 350 constitutes the control means in this embodiment. The operating mode control unit 350 of this embodiment can control the operation of the blower 22 and various refrigeration cycle components 30 according to the operating mode. The operating modes in this embodiment include, for example, operations to cool the user-side heat exchanger 50 (cooling operation, defrosting operation) and operations to heat the user-side heat exchanger 50. The operating mode control unit 350 of this embodiment can control the operating mode based on user operations or the determination results of the defrost feasibility determination unit 340. In particular, in the embodiment described, the operating mode control unit 350 can suppress the decrease in water temperature by controlling the operation so that multiple user-side upstream heat exchangers 50a are not defrosted simultaneously.

[0031] The software blocks described above correspond to functional means realized when the CPU 61 executes the program of this embodiment, thereby enabling each piece of hardware to function. Furthermore, the functional means shown in each embodiment may all be realized in software, or some or all of them may be implemented as hardware that provides equivalent functionality.

[0032] Next, the processes performed by each functional means will be described. Figure 4 is a flowchart showing the processes performed by the refrigeration device 1 of this embodiment. The refrigeration device 1 starts processing from step S1000. In step S1001, the operation mode control unit 350 starts the heating operation of the refrigeration cycle.

[0033] Next, in step S1002, the frost detection unit 330 detects the frost condition of the heat exhaust side heat exchanger 21. The frost detection unit 330 can detect, for example, whether or not frost has formed, and whether the amount of frost is above a predetermined threshold, based on various values ​​measured by the temperature measurement unit 310 and the pressure measurement unit 320.

[0034] In step S1003, the process branches depending on whether or not there is frost exceeding a predetermined threshold. If there is no frost exceeding the threshold (NO), defrosting is deemed unnecessary, and the process returns to step S1002, where the frost condition is detected again and the above process is repeated. On the other hand, if there is frost exceeding the threshold (YES), the process proceeds to step S1004.

[0035] In step S1004, the process branches depending on whether the conditions for performing defrosting are met. The defrosting feasibility determination unit 340 can determine whether the conditions for performing defrosting are met in step S1004. The defrosting feasibility determination unit 340 determines whether the conditions for performing defrosting are met based on the positional relationship between the refrigeration cycle including the exhaust heat exchanger 21 where frost accumulation has not been detected (i.e., the refrigeration cycle that performs heating) and the refrigeration cycle including the exhaust heat exchanger 21 where frost accumulation has been detected (i.e., the refrigeration cycle that is subject to defrosting). If the conditions for performing defrosting are not met (NO), the process returns to step S1002, where frost accumulation is detected again, and the above process is repeated. On the other hand, if the conditions for performing defrosting are met, the process proceeds to step S1005.

[0036] In step S1005, the operation mode control unit 350 controls the refrigeration cycle, including the exhaust heat exchanger 21 where frost has been detected, in a mode for defrosting. That is, by heating the exhaust heat exchanger 21, the frost can be melted and removed.

[0037] Subsequently, in step S1006, the process branches depending on whether or not defrosting of the exhaust heat exchanger 21 has been completed. Whether or not defrosting has been completed can be determined, for example, by the frost detection unit 330 detecting the frost state in the same manner as in step S1002, and determining whether or not the amount of frost has fallen below a predetermined amount. If defrosting has not been completed (NO), the process returns to step S1005 and the defrosting operation continues. On the other hand, if defrosting has been completed, the process proceeds to step S1007, and the refrigeration device 1 terminates its operation. Alternatively, if defrosting has been completed in step S1006, the process may be returned to step S1002 and the above process may be repeated.

[0038] By performing the process shown in Figure 4, the refrigeration system 1 of this embodiment can perform defrosting operations appropriately.

[0039] Up to this point, the processes performed by the refrigeration device 1 of this embodiment have been described. Now, the positional relationship between the refrigeration cycle performing the heating operation and the refrigeration cycle that is the target of the defrosting operation in step S1004 of Figure 4 will be explained.

[0040] Figures 5 and 6 illustrate the positional relationship of the refrigeration cycles performing heating and defrosting operations in this embodiment. Figure 5 shows an example where the refrigeration cycle performing defrosting is located downstream of the refrigeration cycle performing heating operations in the direction of water flow, and Figure 6 shows an example where the refrigeration cycle performing defrosting is located upstream of the refrigeration cycle performing heating operations in the direction of water flow.

[0041] First, the example shown in Figure 5 illustrates a case where the upstream utilization-side heat exchanger 50 is in heating operation, and the downstream utilization-side heat exchanger 50 is in defrosting operation (in other words, it illustrates an example of removing frost from the exhaust-side heat exchanger 21 corresponding to the downstream utilization-side heat exchanger 50). In such a case, as shown in the graph of Figure 5, the water temperature rises as it passes through the upstream utilization-side heat exchanger 50, and then decreases as it passes through the downstream utilization-side heat exchanger 50. That is, since the water that passes through the downstream utilization-side heat exchanger 50 has already reached a higher temperature, the water temperature does not drop significantly.

[0042] On the other hand, the example shown in Figure 6 illustrates a case where the upstream utilization-side heat exchanger 50 is in defrosting operation and the downstream utilization-side heat exchanger 50 is in heating operation (in other words, it illustrates an example of removing frost from the exhaust-side heat exchanger 21 corresponding to the upstream utilization-side heat exchanger 50). In such a case, as shown in the graph of Figure 6, the water temperature decreases as it passes through the upstream utilization-side heat exchanger 50. That is, since the water with increased temperature does not pass through the upstream utilization-side heat exchanger 50, the water temperature drops significantly, which may affect the air-conditioned space and cause the water to freeze. Therefore, it is preferable not to perform the operation shown in Figure 6, which removes frost from the exhaust-side heat exchanger 21 corresponding to the upstream utilization-side heat exchanger 50.

[0043] As shown in Figures 5 and 6, depending on the positional relationship of the refrigeration cycle performing the heating and defrosting operations, there are cases where no problems due to a drop in water temperature occur even when defrosting is performed, and cases where problems due to a drop in water temperature occur when defrosting is performed. Therefore, in step S1004 of Figure 4, the defrost feasibility determination unit 340 can determine whether or not to perform defrosting based on whether or not the water passing through the utilization-side heat exchanger 50 included in the refrigeration cycle, which includes the frosted exhaust-side heat exchanger 21, is in a heated state. For example, in the positional relationship shown in Figure 5, the defrost feasibility determination unit 340 can determine that a predetermined condition is met (assuming that the water passing through the utilization-side heat exchanger 50 connected to the frosted exhaust-side heat exchanger 21 is heated by the utilization-side heat exchanger 50 which is in heating operation), and thus determine to perform defrosting.

[0044] Note that the positional relationships that enable defrosting are not limited to the configuration shown in Figure 5, but can be various other positions. Below, various other configurations that enable defrosting will be described with reference to Figures 7 to 14. Figures 7 to 14 are diagrams illustrating examples of positional relationships of the refrigeration cycle that enable defrosting in this embodiment.

[0045] First, let's explain Figure 7. In this embodiment, the user-side heat exchanger 50 included in the refrigeration system 1 can be configured such as the upstream heat exchanger in Figure 7(a), where one heat exchanger is connected to one refrigeration cycle (i.e., one refrigerant system for one water system; hereinafter referred to as the "single configuration"), or such as the downstream heat exchanger in Figure 7(a), where one heat exchanger is connected to two refrigeration cycles (i.e., two refrigerant systems for one water system; hereinafter referred to as the "dual configuration"). In this embodiment, by performing a heating operation in the refrigeration cycle upstream of the refrigeration cycle performing the defrosting operation, the decrease in water temperature associated with defrosting can be suppressed.

[0046] For example, as shown in Figure 7(a), a configuration can be used in which two single-configuration heat exchangers are arranged in parallel on the upstream side and a dual-configuration heat exchanger is arranged on the downstream side. Alternatively, as shown in Figure 7(b), a configuration can be used in which a dual-configuration heat exchanger is arranged on the upstream side and two single-configuration heat exchangers are arranged in parallel on the downstream side. Furthermore, as shown in Figure 7(c), a configuration can be used in which two single-configuration heat exchangers are arranged in parallel on the upstream side and two single-configuration heat exchangers are arranged in parallel on the downstream side. In the embodiments described, using single-configuration heat exchangers can be suppressed compared to using dual-configuration heat exchangers.

[0047] In the configuration shown in Figures 7(a) to (c), among the patterns in Figure 7(d), the defrost feasibility determination unit 340 can determine that defrost operation is possible in the case of pattern A. That is, when both System 1 and System 2 of the upstream heat exchanger are in heating operation and both System 1 and System 2 of the downstream heat exchanger are in defrost operation, as shown in Figure 5, the water passing through the downstream heat exchanger is warmed by the upstream heat exchanger, so the decrease in water temperature can be suppressed.

[0048] On the other hand, in combinations such as patterns B, C, and D in Figure 7(d), the water passing through the utilization-side heat exchanger 50 of the refrigeration cycle performing defrosting is not heated, as shown in Figure 6, and a decrease in water temperature may occur. Therefore, in such cases, the defrost feasibility determination unit 340 determines that the conditions for performing defrosting are not met.

[0049] Furthermore, while the example shown in Figure 7 involved two user-side heat exchangers 50 arranged in the direction of water flow, a configuration with three or more user-side heat exchangers 50 arranged in the direction of water flow is also possible, as shown in Figures 8 to 14.

[0050] For example, in one embodiment of the refrigeration system 1, as shown in Figure 8, a dual-configuration heat exchanger can be placed on the upstream side, and single-configuration heat exchangers can be placed on the midstream and downstream sides. In this case, as shown in the table in Figure 8, if both upstream heat exchangers are set to heating operation and the midstream and downstream heat exchangers are set to defrost operation, heated water can pass through the heat exchanger performing defrost operation, so the defrost feasibility determination unit 340 can determine that the conditions for defrosting are met. Also, as shown in the table in Figure 8, if one of the upstream heat exchangers is set to heating operation and the other to defrost operation, and the midstream heat exchanger is set to heating operation and the downstream heat exchanger is set to defrost operation, heated water can pass through the downstream heat exchanger performing defrost operation, and in the upstream heat exchanger, the temperature change can be offset by the temperature rise due to heating operation and the temperature drop due to defrost operation, so the defrost feasibility determination unit 340 can determine that the conditions for defrosting are met.

[0051] Furthermore, for example, in the refrigeration device 1 in one embodiment, as shown in Figure 9, a single-configuration heat exchanger can be placed on the upstream side, a dual-configuration heat exchanger on the midstream side, and a single-configuration heat exchanger on the downstream side. In this case, as shown in the table in Figure 9, if the upstream heat exchanger is set to heating operation, one of the midstream heat exchangers is set to heating operation and the other is set to defrost operation, and the downstream heat exchanger is set to defrost operation, then heated water can be passed through the heat exchanger performing the defrost operation, so the defrost feasibility determination unit 340 can determine that the conditions for defrosting are met.

[0052] Furthermore, for example, in the refrigeration device 1 in one embodiment, as shown in Figure 10, a configuration can be adopted in which single-configuration heat exchangers are placed on the upstream and midstream sides, and a dual-configuration heat exchanger is placed on the downstream side. In this case, as shown in the table in Figure 10, when the upstream and midstream heat exchangers are set to heating operation and both downstream heat exchangers are set to defrost operation, heated water can be passed through the heat exchangers performing defrost operation, so the defrost feasibility determination unit 340 can determine that the conditions for defrosting are met. Furthermore, as shown in the table in Figure 10, when the upstream heat exchanger is set to heating operation, the midstream heat exchanger is set to defrost operation, and one of the downstream heat exchangers is set to heating operation and the other is set to defrost operation, heated water can be passed through the midstream heat exchanger that is being defrosted, and in the downstream heat exchanger, the temperature change can be offset by the temperature rise due to the heating operation and the temperature drop due to the defrost operation. Therefore, the defrost feasibility determination unit 340 can determine that the conditions for defrosting are met.

[0053] Furthermore, in one embodiment of the refrigeration system 1, as shown in Figure 11, a configuration can be adopted in which two single-configuration heat exchangers are arranged in parallel on the upstream side, and single-configuration heat exchangers are arranged on the midstream and downstream sides. That is, the configuration shown in Figure 11 is obtained by replacing the dual-configuration heat exchanger on the upstream side of the configuration shown in Figure 8 with two single-configuration heat exchangers arranged in parallel. In this case, as shown in the table in Figure 11, when both upstream heat exchangers are set to heating operation and the midstream and downstream heat exchangers are set to defrost operation, heated water can be passed through the heat exchangers performing defrost operation, so the defrost feasibility determination unit 340 can determine that the conditions for defrosting are met.

[0054] Furthermore, in one embodiment of the refrigeration system 1, as shown in Figure 12, a single-configuration heat exchanger can be placed on the upstream side, two single-configuration heat exchangers can be placed in parallel in the middle, and a single-configuration heat exchanger can be placed on the downstream side. In other words, the configuration shown in Figure 12 is the same as the configuration shown in Figure 9, but with the dual-configuration heat exchanger in the middle replaced by two single-configuration heat exchangers placed in parallel. In this case, as shown in the table in Figure 12, if the upstream heat exchanger is set to heating operation, one of the middle heat exchangers is set to heating operation and the other is set to defrost operation, and the downstream heat exchanger is set to defrost operation, then heated water can be passed through the heat exchanger performing the defrost operation, so the defrost feasibility determination unit 340 can determine that the conditions for defrosting are met.

[0055] Furthermore, in one embodiment of the refrigeration system 1, as shown in Figure 13, a configuration can be adopted in which single-configuration heat exchangers are arranged upstream and midstream, and two single-configuration heat exchangers are arranged in parallel downstream. That is, the configuration shown in Figure 13 is obtained by replacing the dual-configuration heat exchanger on the downstream side with two single-configuration heat exchangers arranged in parallel in the configuration shown in Figure 10. In this case, as shown in the table in Figure 13, when the upstream and midstream heat exchangers are set to heating operation and both downstream heat exchangers are set to defrost operation, heated water can be passed through the heat exchangers performing defrost operation, so the defrost feasibility determination unit 340 can determine that the conditions for defrosting are met. Furthermore, as shown in the table in Figure 13, when the upstream heat exchanger is set to heating operation, the midstream heat exchanger is set to defrost operation, and one of the downstream heat exchangers is set to heating operation and the other is set to defrost operation, heated water can be passed through the midstream heat exchanger that is being defrosted, and in the downstream heat exchanger, the temperature change can be offset by the temperature rise due to the heating operation and the temperature drop due to the defrost operation. Therefore, the defrost feasibility determination unit 340 can determine that the conditions for defrosting are met.

[0056] Furthermore, in the refrigeration device 1 in one embodiment, for example, as shown in Figure 14, four single-component heat exchangers can be arranged in series with respect to the direction of water flow. In this case, as shown in the table in Figure 14, if the uppermost and upstream heat exchangers are set to heating operation and the downstream and last downstream heat exchangers are set to defrost operation, heated water can pass through the heat exchangers performing defrost operation, so the defrost feasibility determination unit 340 can determine that the conditions for defrosting are met. Also, as shown in the table in Figure 14, if the uppermost heat exchanger is set to heating operation, the upstream heat exchangers are set to defrost operation, the downstream heat exchangers are set to heating operation, and the last downstream heat exchanger is set to defrost operation, heated water can pass through the heat exchangers performing defrost operation, so the defrost feasibility determination unit 340 can determine that the conditions for defrosting are met.

[0057] Note that the configuration of the refrigeration system 1 shown in Figures 7 to 14 is an example and does not particularly limit the embodiment. Therefore, this embodiment can be applied to refrigeration systems 1 with configurations other than those shown. Furthermore, according to the configuration of the embodiment described, heated water can be flowed through the heat exchanger performing defrosting, thereby suppressing the drop in water temperature associated with defrosting and preventing impacts on the air-conditioned space and preventing water freezing. In addition, in a refrigeration system 1 that includes multiple refrigeration cycles, in addition to the control based on the positional relationship of the refrigeration cycles as described above, it is preferable to set the upper limit of the number of refrigeration cycles that perform defrosting simultaneously to half the total number of refrigeration cycles. This limits the impact of the drop in water temperature due to defrosting and suppresses a decrease in heating capacity.

[0058] According to the embodiments of the present invention described above, it is possible to provide a refrigeration device that suppresses the decrease in water temperature associated with defrosting.

[0059] Each of the embodiments of the present invention described above can be implemented by a device-executable program written in C, C++, C#, Java®, etc. The program of this embodiment can be stored and distributed on a device-readable recording medium such as a hard disk drive, CD-ROM, MO, DVD, flexible disk, EEPROM®, EPROM, etc., and can also be transmitted over a network in a format that can be used by other devices.

[0060] Although the present invention has been described above with reference to embodiments, the present invention is not limited to the embodiments described above. It is included within the scope of the present invention as long as it achieves the effects and advantages of the present invention within the range of embodiments that a person skilled in the art could deduce. [Explanation of symbols]

[0061] 1...Refrigeration unit, 10...Refrigeration cycle unit, 20...Heat exchanger chamber, 21...Exhaust heat exchanger, 22...Blower, 30...Refrigeration cycle components, 31...Four-way valve, 32...Accumulator, 33...Compressor, 34...Expansion device, 40...Piping, 50...Utilization heat exchanger, 60...Control board, 61...CPU, 62...RAM, 63...ROM, 64...Sensor I / F, 65...Refrigeration cycle I / F, 310...Temperature measurement unit, 320...Pressure measurement unit, 330...Frost detection unit, 340...Defrost feasibility determination unit, 350...Operation mode control unit

Claims

1. Multiple upstream refrigeration cycles having upstream heat exchangers on the user side, Multiple downstream refrigeration cycles having downstream heat exchangers on the user side, The flow path of the heat load medium is connected in series in the order of the upstream heat exchanger on the user side and the downstream heat exchanger on the user side, Control means for simultaneously defrosting multiple downstream refrigeration cycles and preventing simultaneous defrosting of multiple upstream refrigeration cycles. A refrigeration system equipped with the following features.

2. The system further includes a detection means for detecting frost formation on the heat exchanger on the heat exhaust side of the refrigeration cycle. The control means controls the defrosting operation based on the detection result of the detection means. The refrigeration apparatus according to claim 1.

3. The control means is The number of refrigeration cycles performing defrosting operations simultaneously should be less than half of the total number of refrigeration cycles. The refrigeration apparatus according to claim 1.

4. At least one of the aforementioned multiple user-side heat exchangers is configured to have one refrigerant flow path for one heat load medium. The refrigeration apparatus according to claim 1.

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