Refrigeration system

Abstract

To reduce installation costs while increasing waste heat utilization. [Solution] The refrigeration system 1 includes a first chiller 12 that cools a heat transfer medium sent from a heat load facility using electricity or gas and supplies the cooled heat transfer medium to the heat load facility, a second chiller 14 that cools a heat transfer medium sent from a heat load facility using waste heat and supplies the cooled heat transfer medium to the heat load facility, a first piping header 20 provided in a return channel through which the heat transfer medium returning from the heat load facility to the first chiller and the second chiller flows, a second piping header 22 provided in a supply channel through which the heat transfer medium going from the first chiller and the second chiller to the heat load facility flows, a first pump provided in the return channel between the first piping header and the first chiller, a second pump provided in the return channel between the first piping header and the second chiller, a second piping header 22, and a first bypass channel 32 connecting the junction between the first piping header and the first pump in the return channel.

Description

Technical Field

[0004] ,

[0006] , , , ,

[0005] , , , It is a waste heat recovery type refrigerator. , ,

[0001] The present invention relates to a refrigeration system.

Background Art

[0002] For example, Patent Document 1 discloses a refrigeration system having a turbo refrigerator and a steam heat source machine connected to a waste heat supply system. In such Patent Document 1, the primary pump on the inlet side of the turbo refrigerator is under inverter control, and the primary pump on the inlet side of the steam heat source machine is under inverter control, and the flow rate of each primary pump is under inverter control so that the amount of waste heat utilization in the steam heat source machine becomes the largest.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the refrigeration system of Patent Document 1, since a large number of inverters are required, the cost when introducing the refrigeration system becomes high.

[0005] In view of such problems, an object of the present invention is to provide a refrigeration system capable of improving the amount of waste heat utilization while suppressing the introduction cost.

Means for Solving the Problems

[0006] In order to solve the above problems, the refrigeration system of the present invention includes a first refrigerator that cools a heat medium sent from a heat load facility using electric power or gas and supplies the cooled heat medium to the heat load facility, and a heat medium sent from the heat load facility, Emissions from the cogeneration system cool using waste heat It is a waste heat recovery type refrigerator.The system comprises: a second chiller that supplies the cooled heat transfer medium to the heat load equipment; a first piping header provided in the return channel through which the heat transfer medium returning from the heat load equipment to the first chiller and the second chiller flows; a second piping header provided in the supply channel through which the heat transfer medium going from the first chiller and the second chiller to the heat load equipment flows; a first pump provided in the return channel between the first piping header and the first chiller; a second pump provided in the return channel between the first piping header and the second chiller; a second piping header; and a first bypass channel connecting the junction between the first piping header and the first pump in the return channel. The first and second pumps are operated at their rated power using the commercial frequency power of the power grid. . [Effects of the Invention]

[0012] According to the present invention, it is possible to improve the amount of waste heat utilized while suppressing the introduction cost. [Brief explanation of the drawing]

[0013] [Figure 1] Figure 1 is a schematic diagram showing an example of the configuration of a refrigeration system according to the first embodiment. [Figure 2] Figure 2 is a schematic diagram showing an example of the configuration of a refrigeration system according to the second embodiment. [Figure 3] Figure 2 is a schematic diagram showing an example of the configuration of a refrigeration system according to the third embodiment. [Modes for carrying out the invention]

[0014] Preferred embodiments of the present invention will be described in detail below with reference to the attached drawings. The dimensions, materials, and other specific numerical values ​​shown in these embodiments are merely illustrative to facilitate understanding of the invention and do not limit the present invention unless otherwise specified. In this specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals to avoid redundant explanations, and elements not directly related to the present invention are omitted from the illustration.

[0015] (First Embodiment) Figure 1 is a schematic diagram showing an example of the configuration of the refrigeration system 1 of the first embodiment. The refrigeration system 1 comprises a heat load equipment 10, a first chiller 12, a second chiller 14, a return channel 16, a supply channel 18, a first piping header 20, a second piping header 22, a third piping header 24, a first primary pump 26, a second primary pump 28, a secondary pump 30, a first bypass channel 32, and a control device 36.

[0016] The heat load equipment 10 is, for example, an air conditioner (AHU: Air Handling Unit), but is not limited to this example and may be various devices that utilize heat. For example, the heat load equipment 10 includes a heat exchanger capable of cooling air with a heat transfer medium. The cooled air is then blown into a predetermined space.

[0017] The heat transfer medium is, for example, water (chilled water), but is not limited to this example and may be any fluid including liquids or gases. The heat transfer medium circulates between the first chiller 12 and the second chiller 14 and the heat load equipment 10.

[0018] The first chiller 12 cools the heat transfer medium supplied from the heat load equipment 10 using electricity or gas, and supplies the cooled heat transfer medium back to the heat load equipment 10. The first chiller 12 may be, for example, a turbo chiller that uses electricity to cool the heat transfer medium, or an absorption chiller that uses gas to cool the heat transfer medium.

[0019] The second chiller 14 cools the heat transfer medium supplied from the heat load equipment 10 using waste heat, and supplies the cooled heat transfer medium back to the heat load equipment 10. In other words, the second chiller 14 is a waste heat recovery chiller connected to a cogeneration system, which recovers waste heat discharged from the cogeneration system and uses the recovered waste heat to cool the heat transfer medium. In the second chiller 14, the amount of waste heat used increases as the load on the second chiller 14 increases.

[0020] The return flow path 16 is a flow path through which the heat medium that returns from the heat load equipment 10 to the first refrigerator 12 and the second refrigerator 14 flows. The forward flow path 18 is a flow path through which the heat medium that goes from the first refrigerator 12 and the second refrigerator 14 to the heat load equipment 10 flows.

[0021] The first piping header 20 is provided in the middle of the return flow path 16 and can temporarily store the heat medium flowing through the return flow path 16. The second piping header 22 is provided in the middle of the forward flow path 18 and can temporarily store the heat medium flowing through the forward flow path 18. The third piping header 24 is provided between the second piping header 22 and the heat load equipment 10 in the forward flow path 18 and can temporarily store the heat medium flowing through the forward flow path 18.

[0022] The first primary pump 26 is provided in the flow path between the first piping header 20 and the first refrigerator in the return flow path 16. More specifically, the inlet of the first primary pump 26 is connected to the first piping header 20 through a part of the flow path of the return flow path 16. The outlet of the first primary pump 26 is connected to the inlet of the first refrigerator 12 through a part of the flow path of the return flow path 16. The first primary pump 26 sucks the heat medium from the flow path on the first piping header 20 side and discharges the heat medium toward the inlet of the first refrigerator 12. Note that the first primary pump 26 corresponds to the "first pump" in the claims of the present application.

[0023] Although not shown in the figure, electric power from the power system is supplied to the first primary pump 26. The first primary pump 26 is rated-operated by the commercial frequency power of the power system.

[0024] That is, in the refrigerator system 1 of the first embodiment, an inverter for supplying power to the first primary pump 26 is not provided. Therefore, the first primary pump 26 of the refrigerator system 1 of the first embodiment is not inverter-controlled. Therefore, in the refrigerator system 1 of the first embodiment, the flow rate of the heat medium discharged from the first primary pump 26, that is, the discharge amount of the first primary pump 26, is fixed at the rated discharge amount.

[0025] The outlet of the first refrigerator 12 is connected to the second pipe header 22 through a part of the flow path of the forward flow path 18. The heat medium sent out from the outlet of the first refrigerator 12 is sent to the second pipe header 22.

[0026] In FIG. 1, an example in which there is one set of the first refrigerator 12 and the first primary pump 26 is shown, but there may be two or more sets of the first refrigerator 12 and the first primary pump 26.

[0027] The second primary pump 28 is provided in the flow path between the first pipe header 20 and the second refrigerator 14 in the reflux path 16. More specifically, the inlet of the second primary pump 28 is connected to the first pipe header 20 through a part of the flow path of the reflux path 16. The outlet of the second primary pump 28 is connected to the inlet of the second refrigerator 14 through a part of the flow path of the reflux path 16. The second primary pump 28 sucks the heat medium from the first pipe header 20 side and discharges the heat medium toward the inlet of the second refrigerator 14. Note that the second primary pump 28 corresponds to the "second pump" in the claims of the present application.

[0028] Although not shown, power from the power system is supplied to the second primary pump 28. The second primary pump 28 is rated-operated by the commercial frequency power of the power system.

[0029] That is, in the refrigerator system 1 of the first embodiment, an inverter for supplying power to the second primary pump 28 is not provided. Therefore, the second primary pump 28 of the refrigerator system 1 of the first embodiment is not inverter-controlled. Therefore, in the refrigerator system 1 of the first embodiment, the flow rate of the heat medium discharged from the second primary pump 28, that is, the discharge amount of the second primary pump 28 is fixed at the rated discharge amount.

[0030] The outlet of the second refrigerator 14 is connected to the second pipe header 22 through a part of the flow path of the forward flow path 18. The heat medium sent out from the outlet of the second refrigerator 14 is sent to the second pipe header 22.

[0031] Figure 1 shows an example where there is one set of the second chiller 14 and the second primary pump 28, but there may be two or more sets of the second chiller 14 and the second primary pump 28.

[0032] The first primary pump 26 and the second primary pump 28 may have substantially the same specifications. That is, the discharge flow rate of the first primary pump 26 during rated operation and the discharge flow rate of the second primary pump 28 during rated operation may be substantially the same.

[0033] The secondary pump 30 is installed in the flow path between the second piping header 22 and the third piping header 24 of the supply flow path 18. The secondary pump 30 draws in the heat transfer medium from the flow path on the second piping header 22 side and discharges the heat transfer medium on the third piping header 24 side. In other words, the secondary pump 30 can supply the heat transfer medium to the heat load equipment 10 via the third piping header 24.

[0034] The number of secondary pumps 30 may be, for example, the sum of the number of first chillers 12 and the number of second chillers 14. The number of secondary pumps 30 is not limited to two; it may be one or three or more.

[0035] The secondary pump 30, like the first primary pump 26 and the second primary pump 28, may be operated at its rated capacity using the commercial frequency power of the power grid. In this case, the discharge rate of the secondary pump 30 is fixed at its rated discharge rate, and the flow rate of the heat transfer medium supplied to the heat load equipment 10 is substantially fixed at a flow rate according to the rated discharge rate of the secondary pump.

[0036] In Figure 1, a secondary pump 30 and a third piping header 24 were provided. However, the secondary pump 30 and the third piping header 24 may be omitted. In that case, the heat transfer medium delivered from the second piping header 22 may be supplied to the heat load equipment 10.

[0037] The first bypass channel 32 connects the second piping header 22 to the confluence section 40 of the return channel 16 between the first piping header 20 and the first primary pump 26. The first bypass channel 32 recirculates a portion of the heat transfer medium in the second piping header 22 to the confluence section 40. The heat transfer medium recirculated to the confluence section 40 through the first bypass channel 32 mixes with the heat transfer medium flowing from the first piping header 20 into the confluence section 40 and is supplied to the first primary pump 26, from which it is sent to the first refrigerator 12. In other words, the first bypass channel 32 substantially recirculates a portion of the heat transfer medium in the second piping header 22 to the first refrigerator 12.

[0038] The refrigeration system 1 may include an auxiliary bypass channel 50 and an auxiliary valve 52. The auxiliary bypass channel 50 connects the second piping header 22 and the third piping header 24. A portion of the heat transfer medium from the third piping header 24 can be returned to the second piping header 22 through the auxiliary bypass channel 50.

[0039] The auxiliary valve 52 is provided in the auxiliary bypass passage 50 and can adjust the opening degree of the auxiliary bypass passage 50. By adjusting the opening degree of the auxiliary valve 52, the flow rate of the heat transfer medium returning to the second piping header 22 through the auxiliary bypass passage 50 can be adjusted. In other words, by adjusting the opening degree of the auxiliary valve 52, the flow rate of the heat transfer medium supplied by the secondary pump 30 to the heat load equipment 10 can be adjusted.

[0040] The control device 36 has one or more processors 60 and one or more memories 62. The processors 60 function as a control unit 70 that controls the operation of the entire refrigeration system 1 by executing programs contained in the memories 62.

[0041] The control unit 70 can control the operation of the first refrigerator 12 and the second refrigerator 14. For example, the control unit 70 may control the first refrigerator 12 and the second refrigerator 14 so that the temperature of the heat transfer medium at the outlet of the first refrigerator 12 and the temperature of the heat transfer medium at the outlet of the second refrigerator 14 reach a preset target temperature. The control unit 70 may also control the starting and stopping of the first primary pump 26, the second primary pump 28 and the secondary pump 30.

[0042] Generally, the load on a refrigerator can be expressed by multiplying the temperature difference between the heat transfer medium at the refrigerator's inlet and outlet by the flow rate of the heat transfer medium circulating through the refrigerator.

[0043] Here, assuming that the temperature of the heat transfer medium at the outlet of the first chiller 12 is 7°C and the temperature of the heat transfer medium at the outlet of the second chiller 14 is 7°C, the temperature of the heat transfer medium inside the second piping header 22 will be 7°C.

[0044] Furthermore, if the temperature of the heat transfer medium returning from the heat load equipment 10 is 12°C, then the temperature of the heat transfer medium in the first piping header 20 will be 12°C, and the second chiller 14 will be supplied with a heat transfer medium at 12°C through the second primary pump 28. In this case, the temperature difference between the temperature of the heat transfer medium at the inlet of the second chiller 14 and the temperature of the heat transfer medium at the outlet of the second chiller 14 will be 5°C (12°C - 7°C = 5°C).

[0045] In the refrigeration system 1 of the first embodiment, a first bypass channel 32 is provided, so a heat transfer medium at 7°C is supplied from the second piping header 22 through the first bypass channel 32 to the confluence 40 between the first piping header 20 and the first primary pump 26 in the return channel 16.

[0046] As a result, at the confluence section 40, the 12°C heat transfer medium from the first piping header 20 to the first primary pump 26 and the 7°C heat transfer medium from the first bypass flow path 32 to the first primary pump 26 are mixed in a ratio of, for example, 1:4, and the temperature of the heat transfer medium after mixing becomes, for example, 8°C. That is, the first refrigerator 12 is supplied with an 8°C heat transfer medium through the first primary pump 26. Since the temperature of the heat transfer medium at the outlet of the first refrigerator 12 is 7°C, the temperature difference between the temperature of the heat transfer medium at the outlet of the first refrigerator 12 and the temperature of the heat transfer medium at the inlet of the first refrigerator 12 is 1°C (8°C - 7°C = 1°C).

[0047] In other words, a portion of the heat transfer medium in the second piping header 22 is returned to the first chiller 12 through the first bypass passage 32 and the first primary pump 26, but not to the second chiller 14. This relatively reduces the load on the first chiller 12 and relatively increases the load on the second chiller 14.

[0048] In the above example, the load of the heat load equipment 10 is assumed to be 600 RT. Note that RT represents refrigeration ton. Refrigeration ton is a unit of refrigeration capacity and represents the amount of heat required to change 1 ton of water at 0°C into ice at 0°C in 24 hours.

[0049] Here, if the discharge flow rate of the first primary pump 26 and the discharge flow rate of the second primary pump 28 are substantially the same, then the flow rate of the heat transfer medium flowing through the first chiller 12 and the flow rate of the heat transfer medium flowing through the second chiller 14 will be substantially the same. If the flow rate of the heat transfer medium flowing through the first chiller 12 and the flow rate of the heat transfer medium flowing through the second chiller 14 are the same, then the load of the first chiller 12 and the load of the second chiller 14 will be the load of the heat load equipment 10 distributed according to the ratio of the temperature difference in the first chiller 12 and the temperature difference in the second chiller 14.

[0050] For example, if the temperature difference in the first chiller 12 is 1°C and the temperature difference in the second chiller 14 is 5°C, the ratio of the load of the first chiller 12 to the load of the second chiller 14 is 1:5. In this case, if the load of the heat load equipment 10 is 600RT, the load of the first chiller 12 will be 100RT and the load of the second chiller 14 will be 500RT.

[0051] In this example, we have described a case where the merging ratio of the heat transfer medium sent from the first piping header 20 to the merging section 40 and the heat transfer medium sent from the first bypass flow path 32 to the merging section 40 is 1:4, and the load ratio of the load of the first chiller 12 to the load of the second chiller 14 is 1:5. However, the merging ratio of the heat transfer medium and the load ratio of the chillers are not limited to the values ​​shown as an example, and can be set to an appropriate ratio so that the second chiller 14 operates at a relatively higher load compared to the first chiller 12.

[0052] Thus, the refrigeration system 1 of the first embodiment includes a second piping header 22 and a first bypass channel 32 that connects the return channel 16 to the junction portion 40 between the first piping header 20 and the first primary pump 26 (first pump). For this reason, in the refrigeration system 1 of the first embodiment, a portion of the heat transfer medium in the second piping header 22 is returned to the first refrigerator 12, but not to the second refrigerator 14.

[0053] As a result, in the refrigeration system 1 of the first embodiment, the load on the first refrigerator 12, which uses electricity or gas, can be relatively reduced compared to the load on the second refrigerator 14, which uses waste heat, without adjusting the flow rates of the first refrigerator 12 and the second refrigerator 14, that is, without requiring an inverter to adjust the flow rates of the first primary pump 26 and the second primary pump 28. In other words, in the refrigeration system 1 of the first embodiment, the load on the second refrigerator 14, which uses waste heat, can be relatively increased compared to the load on the first refrigerator 12, which uses electricity or gas. When the load on the second refrigerator 14 increases, the amount of waste heat used by the second refrigerator 14 increases.

[0054] As a result, the refrigeration system 1 of the first embodiment can increase the amount of waste heat used by the second refrigerator 14, that is, improve the amount of waste heat utilized, compared to a comparative example that does not have the first bypass flow path 32.

[0055] Furthermore, in the refrigeration system 1 of the first embodiment, the first primary pump 26 and the second primary pump 28 are operated at their rated speed, and the first primary pump 26 and the second primary pump 28 are not inverter-controlled. In other words, there are no inverters corresponding to the first primary pump 26 and no inverters corresponding to the second primary pump 28.

[0056] As a result, the number of inverters required for the refrigeration system 1 in the first embodiment can be reduced, and consequently, the introduction cost of the refrigeration system 1 can be reduced.

[0057] Therefore, the refrigeration system 1 of the first embodiment makes it possible to improve the amount of waste heat utilized while suppressing the introduction cost of the refrigeration system 1.

[0058] (Second Embodiment) Figure 2 is a schematic diagram showing an example of the configuration of the refrigeration system 100 of the second embodiment. For the sake of explanation, the differences from the first embodiment described above will be explained below, and the similarities will not be explained.

[0059] The refrigeration system 100 of the second embodiment has a second bypass channel 132 and a flow meter 134 instead of the first bypass channel 32.

[0060] The second bypass channel 132 connects the second piping header 22 and the first piping header 20. The second bypass channel 132 can return some of the heat transfer medium in the second piping header 22 back to the first piping header 20. A flow meter 134 is installed in the second bypass channel 132. The flow meter 134 detects the flow rate of the heat transfer medium flowing through the second bypass channel 132. The control device 36 can acquire the detection result from the flow meter 134.

[0061] The second primary pump 28, corresponding to the second chiller 14, is operated at its rated capacity using commercial frequency power from the power grid, similar to the first embodiment, and is not inverter controlled. That is, the flow rate of the heat transfer medium discharged from the second primary pump 28 is fixed at the rated discharge rate.

[0062] The refrigeration system 100 of the second embodiment includes a first inverter 140 capable of changing the frequency of the power supplied to the first primary pump 26. The first primary pump 26 operates at a rotational speed according to the frequency of the power supplied from the first inverter 140. That is, the first primary pump 26 corresponding to the first chiller 12 is inverter-controlled by the first inverter 140.

[0063] In the second embodiment, the control unit 70 of the refrigeration system 100 can control the flow rate of the heat transfer medium discharged from the first primary pump 26 by controlling the first inverter 140.

[0064] In the second embodiment, the control unit 70 of the refrigeration system 100 controls the first inverter 140 so that the flow rate of the heat transfer medium discharged from the first primary pump 26 (discharge rate of the first primary pump 26) is less than the flow rate of the heat transfer medium discharged from the second primary pump 28 (discharge rate of the second primary pump 28).

[0065] The control unit 70 may reduce the rotational speed of the first primary pump 26 below its rated rotational speed by supplying power to the first primary pump 26 at a frequency lower than the frequency corresponding to the rated rotational speed of the second primary pump 28, thereby reducing the discharge volume of the first primary pump 26. For example, the control unit 70 may reduce the discharge volume of the first primary pump 26 to approximately 50% of its rated discharge volume.

[0066] The first inverter 140 is controlled so that the discharge rate of the first primary pump 26 is less than the discharge rate of the second primary pump 28. As a result, the flow rate of the heat transfer medium flowing through the first refrigerator 12 becomes less than the flow rate of the heat transfer medium flowing through the second refrigerator 14. In other words, the flow rate of the heat transfer medium flowing through the second refrigerator 14 becomes greater than the flow rate of the heat transfer medium flowing through the first refrigerator 12. Consequently, the load on the first refrigerator 12 becomes relatively smaller than the load on the second refrigerator 14. In other words, the load on the second refrigerator 14 becomes relatively larger than the load on the first refrigerator 12. When the load on the second refrigerator 14 increases, the amount of waste heat used by the second refrigerator 14 increases.

[0067] As a result, in the refrigeration system 100 of the second embodiment, the amount of waste heat used by the second refrigerator 14 can be increased, that is, the amount of waste heat utilized can be improved.

[0068] Furthermore, in the refrigeration system 100 of the second embodiment, the second primary pump 28 is operated at its rated speed and is not inverter-controlled. In other words, there is no inverter corresponding to the second primary pump 28.

[0069] As a result, the number of inverters installed in the refrigeration system 100 of the second embodiment can be reduced, and consequently, the introduction cost of the refrigeration system 100 can be reduced.

[0070] Therefore, in the refrigeration system 100 of the second embodiment, it is possible to improve the amount of waste heat utilized while suppressing the introduction cost of the refrigeration system 100.

[0071] Note that Figure 2 shows an example where there is one set of the first chiller 12 and the first primary pump 26, but there may be two or more sets of the first chiller 12 and the first primary pump 26. Also, Figure 2 shows an example where there is one set of the second chiller 14 and the second primary pump 28, but there may be two or more sets of the second chiller 14 and the second primary pump 28.

[0072] When there are two or more sets of the first chiller 12 and the first primary pump 26, it is not limited to the example where all of the first primary pumps 26 are inverter-controlled by the first inverter 140. It is sufficient that at least one of the first primary pumps 26 is inverter-controlled by the first inverter 140.

[0073] In Figure 2, a secondary pump 30 and a third piping header 24 were provided. However, the secondary pump 30 and the third piping header 24 may be omitted. In that case, the heat transfer medium delivered from the second piping header 22 may be supplied to the heat load equipment 10.

[0074] Here, when the first inverter 140 supplies power to the first primary pump 26 at a frequency that causes the first primary pump 26 to reach its rated rotational speed, some of the heat transfer fluid in the second piping header 22 moves to the first piping header 20 through the second bypass flow path 132.

[0075] If power at a frequency lower than the frequency at which the first primary pump 26 operates at its rated speed is supplied to the first primary pump 26, the rotational speed of the first primary pump 26 will decrease below its rated speed. As a result, the discharge rate of the first primary pump 26 will decrease compared to the discharge rate at its rated speed, and the flow rate through the first chiller 12 will decrease compared to the flow rate when the first primary pump 26 is operating at its rated speed. Consequently, the second bypass flow rate of the second bypass passage 132, that is, the flow rate of the heat transfer medium flowing from the second piping header 22 to the first piping header 20 through the second bypass passage 132, will decrease.

[0076] Furthermore, if the flow rate through the first chiller 12 decreases excessively, the heat transfer medium will move in the second bypass channel 132 in the direction from the first piping header 20 towards the second piping header 22. If the heat transfer medium in the first piping header 20, before being cooled, is sent to the second piping header 22 through the second bypass channel 132 without being cooled by the first chiller 12 and the second chiller 14, the cooling effect in the heat load equipment 10 will decrease.

[0077] With that in mind, when controlling the first inverter 140 so that the discharge rate of the first primary pump 26 is less than the discharge rate of the second primary pump 28, it is preferable to control the flow so that the heat transfer medium does not flow through the second bypass passage 132 in the direction from the first piping header 20 to the second piping header 22.

[0078] For example, the control unit 70 can obtain a second bypass flow rate from the flow meter 134, which indicates the flow rate of the heat transfer medium flowing from the second piping header 22 to the first piping header 20 through the second bypass flow path 132. The control unit 70 may also control the first inverter 140 to reduce the second bypass flow rate under conditions where the discharge rate of the first primary pump 26 is less than the discharge rate of the second primary pump 28 and the second bypass flow rate is 0 or greater.

[0079] More preferably, the control unit 70 may control the first inverter such that the discharge rate of the first primary pump 26 becomes less than the discharge rate of the second primary pump 28, and the second bypass flow rate becomes zero.

[0080] In the refrigeration system 100 of the second embodiment, by setting the second bypass flow rate to 0, the flow rate and load of the first chiller 12 can be minimized while suppressing a decrease in the cooling effect in the heat load equipment 10, thereby relatively maximizing the flow rate and load of the second chiller 14. In other words, in the refrigeration system 100 of the second embodiment, by setting the second bypass flow rate to 0, the amount of waste heat used by the second chiller 14 can be maximized while suppressing a decrease in the cooling effect in the heat load equipment 10.

[0081] (Third embodiment) Figure 3 is a schematic diagram showing an example of the configuration of the refrigeration system 200 of the third embodiment. For the sake of explanation, the differences between this embodiment and the first and second embodiments described above will be explained below, while the commonalities will not be explained.

[0082] The second primary pump 28, corresponding to the second chiller 14, is operated at its rated capacity using commercial frequency power from the power grid, similar to the first and second embodiments, and is not inverter controlled. That is, the flow rate of the heat transfer medium discharged from the second primary pump 28 is fixed at the rated discharge rate.

[0083] The refrigeration system 200 of the third embodiment, like the second embodiment, includes a first inverter 140 capable of changing the frequency of the power supplied to the first primary pump 26. The first primary pump 26 operates at a rotational speed according to the frequency of the power supplied from the first inverter 140. That is, the first primary pump 26 corresponding to the first chiller 12 is inverter-controlled by the first inverter 140.

[0084] The control unit 70 of the refrigeration system 200 of the third embodiment can control the flow rate of the heat transfer medium discharged from the first primary pump 26 (discharge amount of the first primary pump) by controlling the first inverter 140.

[0085] As shown in Figure 3, in the third embodiment of the refrigeration system 200, the secondary pump 30, third piping header 24, auxiliary bypass flow path 50, and auxiliary valve 52 of the first and second embodiments are omitted. Therefore, in the third embodiment of the refrigeration system 200, the heat transfer medium from the second piping header 22 is supplied to the heat load equipment 10. In the third embodiment of the refrigeration system 200, since the secondary pump 30 is not provided, the heat transfer medium supplied from the second piping header 22 to the heat load equipment 10 is substantially the sum of the flow rate of the heat transfer medium flowing through the first chiller 12 and the flow rate of the heat transfer medium flowing through the second chiller 14. Therefore, the flow rate of the heat transfer medium delivered from the second piping header 22 is variable.

[0086] Furthermore, a secondary pump 30, a third piping header 24, an auxiliary bypass channel 50, and an auxiliary valve 52 may be provided in the refrigeration system 200 of the third embodiment.

[0087] The refrigeration system 200 of the third embodiment has a third bypass channel 232 instead of the first bypass channel 32 and the second bypass channel 132.

[0088] The third bypass channel 232 connects the diversion section 234 between the second piping header 22 and the heat load equipment 10 in the supply channel 18 and the merging section 236 between the heat load equipment 10 and the first piping header 20 in the return channel 16. The third bypass channel 232 can send at least a portion of the heat transfer medium in the second piping header 22 to the first piping header 20, bypassing the heat load equipment 10.

[0089] The refrigeration system 200 of the third embodiment may have a three-way valve 238. The three-way valve 238 is provided at the junction 236 between the heat load equipment 10 and the first piping header 20 in the return flow path 16. The three-way valve 238 can adjust the opening of the inlet on the heat load equipment 10 side and the opening of the inlet on the third bypass flow path 232 side. In other words, the three-way valve 238 can adjust the ratio between the opening of the inlet on the heat load equipment 10 side and the opening of the inlet on the third bypass flow path 232 side, or in other words, the ratio between the flow rate of the heat transfer medium flowing through the heat load equipment 10 and the flow rate of the heat transfer medium flowing through the third bypass flow path 232. The three-way valve 238 may be controlled by a control unit 70.

[0090] In the third embodiment, the control unit 70 of the refrigeration system 200 controls the first inverter 140 such that the flow rate of the heat transfer medium discharged from the first primary pump 26 (discharge rate of the first primary pump 26) is less than the flow rate of the heat transfer medium discharged from the second primary pump 28 (discharge rate of the second primary pump 28). This control causes the flow rate of the heat transfer medium circulating through the first refrigerator 12 to be less than the flow rate of the heat transfer medium circulating through the second refrigerator 14. In other words, the flow rate of the heat transfer medium circulating through the second refrigerator 14 is greater than the flow rate of the heat transfer medium circulating through the first refrigerator 12.

[0091] As a result, the load on the first refrigerator 12 becomes relatively smaller than the load on the second refrigerator 14. In other words, the load on the second refrigerator 14 becomes relatively larger than the load on the first refrigerator 12. When the load on the second refrigerator 14 increases, the amount of waste heat used by the second refrigerator 14 increases.

[0092] As a result, in the refrigeration system 200 of the third embodiment, the amount of waste heat used by the second refrigerator 14 can be increased, that is, the amount of waste heat utilized can be improved.

[0093] Furthermore, in the refrigeration system 200 of the third embodiment, the second primary pump 28 is operated at its rated speed and is not inverter-controlled. In other words, there is no inverter corresponding to the second primary pump 28.

[0094] As a result, the number of inverters required for the refrigeration system 200 in the third embodiment can be reduced, and consequently, the introduction cost of the refrigeration system 200 can be reduced.

[0095] Therefore, the refrigeration system 200 of the third embodiment makes it possible to improve the amount of waste heat utilized while suppressing the introduction cost.

[0096] Furthermore, the refrigeration system 200 of the third embodiment may include an inlet thermometer 240 for detecting the temperature of the heat transfer medium at the inlet of the first refrigerator 12, and an outlet thermometer 242 for detecting the temperature of the heat transfer medium at the outlet of the first refrigerator 12. The control unit 70 of the third embodiment may obtain the temperature of the heat transfer medium at the inlet of the first refrigerator 12 from the inlet thermometer 240 and the temperature of the heat transfer medium at the outlet of the first refrigerator 12 from the outlet thermometer 242.

[0097] In the third embodiment, the control unit 70 may control the first inverter 140 so that the temperature difference between the temperature of the heat transfer medium at the outlet of the first refrigerator 12 and the temperature of the heat transfer medium at the inlet of the first refrigerator 12 is maintained at a predetermined value. That is, in the refrigerator system 200 of the third embodiment, the first inverter 140 is controlled so that the temperature difference in the first refrigerator 12 remains constant.

[0098] As a result, even if the load of the heat load equipment 10 fluctuates, the flow rate through the first chiller 12 is adjusted by the control of the first inverter 140, and consequently, the load of the first chiller 12 is appropriately adjusted so that the load of the first chiller 12 is relatively smaller than the load of the second chiller 14.

[0099] As a result, in the refrigeration system 200 of the third embodiment, the load handled by the first refrigeration unit 12 can be finely adjusted while the proportion of the load handled by the second refrigeration unit 14 is set to a relatively large value, thereby appropriately dealing with the load of the thermal load equipment 10.

[0100] Preferred embodiments of the present invention have been described above with reference to the attached drawings, but it goes without saying that the present invention is not limited to these embodiments. It is clear to those skilled in the art that various modifications or alterations can be conceived within the scope of the claims, and these will naturally also fall within the technical scope of the present invention. [Explanation of Symbols]

[0101] 1, 100, 200 Refrigeration System 10 Heat load equipment 12. First Refrigeration Unit 14. Second Refrigeration Unit 16 Recirculation channel 18 Outbound flow path 20. First piping header 22. Second Piping Header 26. First primary pump (first pump) 28. Second primary pump (second pump) 32 First Bypass Channel 36 Control device 40 Confluence section 132 Second Bypass Channel 140 First Inverter 232 Third Bypass Channel 234 Diversion section 236 Confluence section

Claims

[Claim 1] A first chiller cools a heat transfer medium sent from a heat load facility using electricity or gas, and supplies the cooled heat transfer medium back to the heat load facility. A waste heat recovery chiller that cools the heat transfer medium sent from the heat load equipment using waste heat discharged from a cogeneration system, and a second chiller that supplies the cooled heat transfer medium to the heat load equipment, A first piping header is provided in the return channel through which the heat transfer medium returning from the heat load equipment to the first and second chillers flows, A second piping header is provided in the supply channel through which the heat transfer medium flows from the first and second refrigerators to the heat load equipment, A first pump is provided in the flow path between the first piping header and the first refrigerator, among the aforementioned return flow paths. A second pump is provided in the flow path between the first piping header and the second refrigerator in the aforementioned return flow path, A first bypass channel connecting the second piping header and the junction portion of the return channel between the first piping header and the first pump, Equipped with, The first pump and the second pump are operated at their rated power using the commercial frequency power of the power grid. Refrigeration system.

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