Heat source system, heat source machine, control device

Abstract

The heat source system 1 of the embodiment includes an inlet side pressure gauge 17 that is provided on the inlet side where water flows into the water-refrigerant heat exchanger 9 from the return pipe and detects the pressure of the water flowing through the return pipe upstream of the inlet pump 10 that sends water to the water-refrigerant heat exchanger 9, an outlet side pressure gauge that is provided on the outlet side where water flows out from the water-refrigerant heat exchanger 9 to the water supply pipe 5 and detects the pressure of the water flowing through the water supply pipe 5, and a control device 16 that executes processing to control the bypass valve 2 provided in the bypass pipe 7 based on the difference between the inlet side pressure detected by the inlet side pressure gauge 17 and the outlet side pressure detected by the outlet side pressure gauge.

Description

[Technical Field]

[0001] An embodiment of the present invention relates to a heat source system in which a heat source machine and a load device are connected by a water supply pipe and a water return pipe, and to a heat source machine and a control device used therein. [Background technology]

[0002] Conventionally, heat source systems that are configured by connecting a heat source machine and a load device with water supply pipes and return pipes have been used in a wide range of fields, such as for air conditioning in buildings, industrial applications such as painting, drying, and cleaning, and agricultural applications such as cultivation.

[0003] Such heat source systems are configured as a single pump system in which a pump is installed only on the heat source machine side, or as a dual pump system in which a pump is installed on the load device side as well.In either configuration, various sensors such as differential pressure gauges, flow rate sensors, and temperature sensors are installed in the water supply pipes, return pipes, etc. to obtain the data necessary for control (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-38379 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-35090 Summary of the Invention [Problem to be solved by the invention]

[0005] As in Patent Documents 1 and 2, installing more types and numbers of sensors will increase the amount of data acquired, which is thought to be useful for controlling the heat source system. On the other hand, installing more types and numbers of sensors will not only increase costs, but may also require a great deal of effort when starting up and operating the heat source system.

[0006] Therefore, the present invention provides a heat source system, a heat source machine, and a control device that can reduce the number and types of sensors to be installed and improve convenience during start-up and operation. [Means for solving the problem]

[0007] The heat source system of this embodiment is characterized by comprising: an inlet pressure gauge located on the inlet side where water flows into the water-refrigerant heat exchanger from the return pipe, and detecting the pressure of the water flowing through the return pipe upstream of the inlet pump that sends water to the water-refrigerant heat exchanger; an outlet pressure gauge located on the outlet side where water flows out of the water-refrigerant heat exchanger into the water supply pipe, and detecting the pressure of the water flowing through the water supply pipe; and a control device that executes processing to control a bypass valve located in a bypass pipe that connects the water supply pipe and the return pipe in parallel to a load device, based on the difference between the inlet pressure detected by the inlet pressure gauge and the outlet pressure detected by the outlet pressure gauge. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram illustrating a configuration of a single-pump heat source system according to a first embodiment and a second embodiment. [Figure 2] FIG. 10 is a diagram schematically illustrating another configuration of a single-pump heat source system according to the third embodiment. [Figure 3] FIG. 10 is a diagram illustrating a configuration of a double-pump heat source system according to a fourth embodiment. [Figure 4] FIG. 13 is a diagram schematically illustrating another configuration of a double-pump type heat source system according to the fifth embodiment. [Figure 5] FIG. 13 is a diagram schematically illustrating a piping configuration of a heat source system according to a sixth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Several embodiments will be described below. While details will be provided later, the first to third embodiments are examples of a single pump system, the fourth and fifth embodiments are examples of a double pump system, and the sixth embodiment is a modified example thereof. For ease of explanation, the heat source systems of the respective embodiments are denoted by the same reference numerals.

[0010] (First embodiment) In the first embodiment, an example will be described in which a bypass valve 2 (see FIG. 1) is controlled based on the differential pressure between the inlet and outlet sides of a heat source unit 3 (see FIG. 1) in a simplex pump type heat source system 1 (see FIG. 1). Here, the simplex pump type may be rephrased as a primary pump type, for example.

[0011] As shown in Figure 1, the heat source system 1 includes a heat source machine 3, a load device 4, a water supply pipe 5 and a water return pipe 6 for circulating water between the heat source machine 3 and the load device 4, and water adjusted to a predetermined temperature by the heat source machine 3 is sent via the water supply pipe 5 to various load devices 4, such as air conditioning devices that condition buildings or cleaning devices and drying devices installed in factories, while water from the load device 4 is returned to the heat source machine 3 through the water return pipe 6. Note that in Figure 1, the direction of water flow is conveniently indicated by outline arrows.

[0012] The heat source system 1 is also provided with a bypass pipe 7 that connects the water supply pipe 5 and the return water pipe 6 in parallel with the load device 4, and a bypass valve 2 that adjusts the flow of water in the bypass pipe 7. The amount of water flowing through the bypass pipe 7 is adjusted by controlling the bypass valve 2, more specifically, by adjusting the opening degree of the bypass valve 2. The return water pipe 6 is also connected to an expansion tank 8 that applies pressure to the water flowing through the return water pipe 6, and the outlet of the expansion tank 8 is connected to the return water pipe 6.

[0013] A plurality of heat source units 3, for example, two to a dozen, are installed based on the required specifications and to enable backup in case of failure. Each heat source unit 3 includes a water-refrigerant heat exchanger 9 that exchanges heat between water and a refrigerant, an inlet pump 10 that sends water to the water-refrigerant heat exchanger 9 at a predetermined pressure, a water-side inlet pressure gauge 12 provided in an inlet pipe 11 through which water flows into the water-refrigerant heat exchanger 9, a water-side outlet pressure gauge 14 provided in an outlet pipe 13 through which water flows out of the water-refrigerant heat exchanger 9, a unit controller 15, etc.

[0014] As is well known, the water-refrigerant heat exchanger 9 exchanges heat between water and a refrigerant, and may be, for example, a double-pipe heat exchanger in which the water pipe and the refrigerant pipe have a double-pipe structure, a plate heat exchanger separated by multiple plates, or a structure in which the refrigerant pipe is arranged in a serpentine manner inside a water container. In this embodiment, multiple water-refrigerant heat exchangers 9 are provided in each heat source unit 3. The water-refrigerant heat exchanger 9 may be one that can produce so-called hot water, one that can produce so-called cold water, or one that can produce both hot water and cold water, as appropriate for the purpose.

[0015] The inlet pump 10 is controlled by an inverter (not shown), and is provided in the inlet piping 11 of the water-refrigerant heat exchanger 9, between the return pipe 6 and the water-refrigerant heat exchanger 9. The inlet pump 10 adjusts the pressure of the water flowing through the return pipe 6 to a predetermined level before sending it to the water-refrigerant heat exchanger 9, so that the water is sent to the water-refrigerant heat exchanger 9 at a constant pressure. The inlet pump 10 also functions as a drive source for sending water to the load device 4. This system of sending water to the load device 4 using a pump provided in the heat source unit 3 is called a single pump system.

[0016] Water-side inlet pressure gauge 12 is provided between water-refrigerant heat exchanger 9 and inlet pump 10, and detects the pressure of water adjusted to a predetermined pressure by inlet pump 10. Therefore, the water pressure detected by water-side inlet pressure gauge 12 is higher than the pressure of water flowing through return pipe 6. In other words, water-side inlet pressure gauge 12 does not measure the pressure of water flowing through return pipe 6.

[0017] Water-side outlet pressure gauge 14 detects the pressure of water that has been heat exchanged in water-refrigerant heat exchanger 9 and adjusted to a predetermined temperature and flows out of outlet piping 13 of water-refrigerant heat exchanger 9. Because outlet piping 13 is directly connected to water supply pipe 5, the water pressure detected by water-side outlet pressure gauge 14 can be considered to roughly match the pressure of water flowing through water supply pipe 5. In other words, water-side outlet pressure gauge 14 can essentially detect the pressure of water flowing through water supply pipe 5 upstream of the branch point with bypass pipe 7. This water-side outlet pressure gauge 14 corresponds to an outlet-side pressure gauge.

[0018] The unit controller 15 controls each heat source unit 3 individually, for example, by executing a process to determine the flow rate of water flowing through the water-refrigerant heat exchanger 9 (hereinafter referred to as the chiller flow rate) based on the difference in water pressure detected by the water-side inlet pressure gauge 12 and the water-side outlet pressure gauge 14. The unit controller 15 is connected to a control device 16 that controls the entire heat source system 1.

[0019] In this embodiment, the control device 16 is built into one of the multiple heat source devices 3 installed, and outputs control commands to each heat source device 3 for controlling the heat source system 1, and acquires information indicating the operating state, such as the chiller flow rate described above, from each heat source device 3. The control device 16 is also connected directly to the load device 4 or indirectly via the control unit of the load device 4, and is able to acquire information indicating the operating state of the load device 4. Hereinafter, the heat source device 3 with this built-in control device 16 will be referred to as the representative device for convenience.

[0020] The control device 16 is also connected to the bypass valve 2 and the expansion tank 8, and can be configured to adjust the opening of the bypass valve 2 provided in the bypass pipe 7 and obtain the pressure (control pressure) applied from the expansion tank 8 to the water flowing through the return pipe 6. The control pressure may be, for example, the pressure value itself set in the expansion tank 8 by the control device 16, or it may be a control value that can identify the pressure value to be set.

[0021] The heat source unit 3 provided with the control device 16 is also provided with an inlet pressure gauge 17. This inlet pressure gauge 17 is provided upstream of the inlet pump 10 in the flow of water flowing into the water-refrigerant heat exchanger 9, and detects the pressure of the water taken in by the inlet pump 10. More specifically, the inlet pressure gauge 17 is provided on the suction port side directly connected to the return water pipe 6. Therefore, unlike the water inlet pressure gauge described above, the inlet pressure gauge 17 can detect the pressure of the water flowing through the return water pipe 6.

[0022] In this embodiment, the inlet pressure gauge 17 is built into the heat source unit 3 that serves as the representative unit. This representative unit is connected in such a way that the inflowing water branches off from the return water pipe 6 at a position closest to the load device 4, and the outflowing water joins the water supply pipe 5 at a position closest to the load device 4. The other heat source units 3 other than the representative unit are connected in such a way that water branches off from the return water pipe 6 downstream of the representative unit and flows out into the water supply pipe 5 upstream of the representative unit. Connections 18 are provided between each heat source unit 3 and the water supply pipe 5 and the return water pipe 6.

[0023] Next, the operation of the above-described configuration will be described. The inlet pump 10 is used to send water at a predetermined pressure to the water-refrigerant heat exchanger 9, and as described above, also functions as a drive source to send water to the load device 4. If the shutoff valve 4a on the load device 4 side is closed, for example, because the operation of the load device 4 is stopped, the flow of water on the discharge side of the inlet pump 10, i.e., in the water supply pipe 5, will be blocked or obstructed.

[0024] If the flow of water in the water supply pipe 5 is blocked or obstructed, the inlet pump 10 will enter a so-called shut-off operation state, which may cause a rise in temperature, leading to malfunction or the generation of noise and vibration. This also applies if the flow of water in the suction side of the inlet pump 10, i.e., the return pipe 6, is blocked or obstructed.

[0025] For this reason, in the past, various sensors such as a flow meter, a temperature sensor, or a differential pressure gauge installed between the water supply pipe 5 and the return pipe 6 were installed, and for example, for the bypass valve 2, PID control was performed to ensure appropriate water flow based on the differential pressure between the water pressure in the water supply pipe 5 and the water pressure in the return pipe 6.

[0026] Incidentally, although the bypass valve 2 can be controlled based on the differential pressure, there is a problem that is difficult to solve simply by obtaining the differential pressure when actually operating the heat source system 1. As is well known, the lower the applied pressure, the easier it is for water to boil, so if the pressure of the water flowing through the return pipe 6 becomes lower than a reference value such as atmospheric pressure, cavitation or the like occurs, which can lead to malfunctions.

[0027] Therefore, in reality, in addition to the differential pressure gauge, a pressure gauge is also provided to detect the pressure of the water flowing through the return pipe 6 for each of the different control purposes. In other words, in the past, separate sensors were provided for the different controls of obtaining the differential pressure and monitoring the pressure on the return pipe 6 side, which tended to increase the number and types of sensors.

[0028] However, if the number and types of sensors to be installed increase, not only will costs simply increase, but adjustments will be required for each sensor, requiring a great deal of effort not only at the start-up but also during operation of the heat source system 1. Furthermore, because sensors to be installed in piping are generally installed by the contractor, there is a risk that the installed sensors may differ from the specifications, which could cause malfunctions from the perspective of the heat source unit 3, leading to unexpected problems.

[0029] Therefore, as described above, the heat source system 1 is provided with an inlet side pressure gauge 17 that detects the pressure of the water flowing in the return pipe 6 upstream of the inlet pump 10 of the representative heat source unit 3, and controls the bypass valve 2 based on the difference between the inlet side pressure gauge 17 and the outlet side pressure gauge that is provided at the water side outlet of the water-refrigerant heat exchanger 9 and actually detects the pressure of the water flowing in the water supply pipe 5.

[0030] This eliminates the need for the differential pressure gauge that was previously installed. Also, since the outlet pressure gauge is already installed for the water-refrigerant heat exchanger 9, the number of sensors does not increase. This makes it possible to reduce the number and types of sensors. Furthermore, if the number and types of sensors to be installed can be reduced, convenience during start-up, operation, and maintenance will be improved.

[0031] In this case, the pressure of the water flowing through the water supply pipe 5 can be, for example, the detected value of the outlet pressure gauge installed on the representative heat source unit 3, or the maximum, minimum, average, or representative value of the detected values of the outlet pressure gauges of multiple heat source units 3 in operation can be used.

[0032] Furthermore, in the heat source system 1, the inlet pressure gauge 17 is installed inside the heat source machine 3, and is therefore prepared by the manufacturer of the heat source machine 3. This reduces the risk of problems occurring, such as the installed sensor not meeting specifications, as in the past. Furthermore, since there is no need to extend wiring to the piping side as with conventional differential pressure gauges, installation costs can also be reduced.

[0033] In this way, the types and number of sensors to be installed can be reduced in the heat source system 1, the heat source machine 3, and the control device 16, and convenience during start-up and operation is improved. Of course, since the inlet pressure gauge 17 can detect the pressure of the water flowing through the return pipe 6, it is also possible to control the expansion tank 8 to apply pressure when the water pressure is lower than atmospheric pressure, for example.

[0034] According to the heat source system 1, the heat source unit 3, and the control device 16 described above, the following effects can be obtained. The heat source system 1 includes an inlet pressure gauge 17 that detects the pressure of water flowing through the return pipe 6 upstream of the inlet pump 10, an outlet pressure gauge that is provided on the outlet side where water flows out from the water-refrigerant heat exchanger 9 to the water supply pipe 5 and detects the pressure of the water flowing through the water supply pipe 5, and a control device 16 that executes processing to control the bypass valve 2 provided in the bypass pipe 7 that connects the water supply pipe 5 and the return pipe 6 in parallel with the load device 4 based on the difference between the inlet pressure detected by the inlet pressure gauge 17 and the outlet pressure detected by the outlet pressure gauge.

[0035] This makes it possible to control the bypass valve 2 based on the detection results of the inlet side pressure gauge 17 and the outlet side pressure gauge, eliminating the need to install the differential pressure gauge that was previously installed, and also making it possible to use the inlet side pressure gauge 17 to monitor the pressure on the return pipe 6 side, thereby reducing the number and types of sensors to be installed.

[0036] Also, because the bypass valve 2 is controlled based on the differential pressure, the occurrence of the shut-off operation described above can be prevented, and the risk of breakdown can be reduced. Furthermore, since the inlet pressure gauge 17 is provided in the heat source machine 3, the manufacturer of the heat source machine 3 will provide the inlet pressure gauge 17, which makes it possible to avoid the above-mentioned unexpected troubles, etc., and improves convenience during start-up and operation.

[0037] The heat source unit 3 used in the heat source system 1 also includes a water-refrigerant heat exchanger 9 and a control device 16 that controls a bypass valve 2 provided in a bypass pipe 7 connecting the water supply pipe 5 and the return pipe 6 in parallel with the load device 4 based on the difference between the water pressure detected by an inlet pressure gauge 17 and the water pressure detected by an outlet pressure gauge—that is, the difference between the pressures on the inlet and outlet sides of the heat source unit 3 or the water-refrigerant heat exchanger 9. This heat source unit 3, like the heat source system 1 described above, can reduce the number and types of sensors to be installed and improve convenience during startup and operation. It also shortens the construction period and reduces costs when building a heat source system.

[0038] Furthermore, the control device 16 that controls the heat source system 1 executes a process to control the bypass valve 2 provided in the bypass pipe 7 that connects the water supply pipe 5 and the return pipe 6 in parallel with the load device 4, based on the difference between the water pressure on the inlet side and the water pressure on the outlet side. As with the heat source system 1 described above, this control device 16 also makes it possible to reduce the number and types of sensors to be installed, and to improve convenience during start-up and operation.

[0039] (Second embodiment) In the second embodiment, a process for determining the amount of water flowing to the load device 4 side in a simplex pump type heat source system 1 will be described. Note that the configuration of the heat source system 1 is the same as in the first embodiment, and therefore the description will be made with reference to FIG. 1.

[0040] The heat source system 1 of this embodiment has a configuration common to the first embodiment, and includes the above-mentioned heat source unit 3, load device 4, water supply pipe 5 and return pipe 6, inlet side pressure gauge 17, water side outlet pressure gauge 14 corresponding to the outlet side pressure gauge, and control device 16.

[0041] When operating the heat source system 1, it is necessary to appropriately control the amount of water flowing on the load device 4 side. Hereinafter, for convenience, the portion of the water supply pipe 5 that is closer to the load device 4 than the branch point with the bypass pipe 7 will be referred to as the load side water supply section 5a, and the amount of water flowing through this load side water supply section 5a will be referred to as the load flow rate (F2; see Figure 1). Also, for convenience, the portion of the return pipe 6 that is closer to the load device 4 than the branch point with the bypass pipe 7 will be referred to as the load side return water section 6a.

[0042] Therefore, in the past, a flow meter was installed in the load side return water section 6a to directly obtain the load flow rate (F2), or a thermometer to detect the water temperature was installed in each of the load side water supply section 5a and the load side return water section 6a, and the load flow rate (F2) was estimated based on the temperature difference.

[0043] In contrast, in the heat source system 1 of this embodiment, the load flow rate (F2) is calculated based on the difference in pressure detected by the inlet pressure gauge 17 and the outlet pressure gauge, and the opening and mechanical characteristics of the bypass valve 2.

[0044] First, the control device 16 calculates the total amount of water supplied from the heat source units 3. Hereinafter, the total amount of water supplied from the heat source units 3 is referred to as the total flow rate (F1; see FIG. 1). In this case, the total flow rate (F1) is considered to be the sum of the amounts of water (chiller flow rates) supplied from each heat source unit 3 that is in operation.

[0045] At this time, the chiller flow rate of each heat source unit 3 in operation is controlled by the respective unit controllers 15. Therefore, the control device 16 can obtain the respective chiller flow rates from the respective unit controllers 15 and add them up to determine the total flow rate (F1).

[0046] Next, the control device 16 determines the amount of water flowing through the bypass pipe 7 from the aperture of the bypass valve 2 and the mechanical characteristics of the bypass valve 2. Hereinafter, the amount of water flowing through the bypass pipe 7 will be referred to as the bypass flow rate (F3; see FIG. 1). Here, the amount of water that can pass through the bypass valve 2 is f, the valve aperture of the bypass valve 2 is v, the flow rate when the bypass valve 2 is fully open is Cv, the rangeability indicating the adjustment range is r, the density of water is ρ, the gravitational acceleration is G, and the pressure difference between the inlet and outlet sides of the water-refrigerant heat exchanger 9 is ΔP.

[0047] The amount of water (f) that can pass through the bypass valve 2 can be calculated as follows, depending on whether the valve type is equal percentage characteristic or linear characteristic. Note that "·" indicates multiplication, " / " indicates division, and "^" indicates exponentiation. In the case of equal percentage characteristics f=Cv·r^(v / 100-1) For linear characteristics f=Cv (1 / r + (1 - 1 / r) (v / 100))

[0048] At this time, the bypass flow rate (F3) is calculated as follows: F3=f / (0.07·(ρ / (G·ΔP))^0.5) Once the total flow rate (F1) and the bypass flow rate (F3) are determined in this way, the load flow rate (F2) can be determined as follows: F2=F1-F3

[0049] Then, the control device 16 controls the heat source system 1 so that the calculated load flow rate (F2) falls within an appropriate range. In this way, the heat source system 1 of this embodiment can calculate the load flow rate (F2) based on the difference between the pressures detected by the inlet pressure gauge 17 and the outlet pressure gauge, and the opening and mechanical characteristics of the bypass valve 2, eliminating the need to install conventional flow meters and thermometers. This makes it possible to reduce the number and types of sensors to be installed.

[0050] Furthermore, since the inlet pressure gauge 17 is provided in the heat source machine 3, the manufacturer of the heat source machine 3 will provide the inlet pressure gauge 17, which makes it possible to avoid the unexpected troubles mentioned above, thereby improving convenience during start-up and operation.

[0051] The heat source unit 3 used in the heat source system 1 also includes a water-refrigerant heat exchanger 9 and a control device 16 that executes a process to calculate the load flow rate (F2) flowing to the load device 4 side based on the difference between the water pressure on the inlet side and the water pressure on the outlet side. As with the heat source system 1 described above, this heat source unit 3 also makes it possible to reduce the number and types of sensors to be installed, and to improve convenience during start-up and operation. It also makes it possible to shorten the construction period and reduce costs when building a heat source system.

[0052] Furthermore, the control device 16 that controls the heat source system 1 executes a process to calculate the load flow rate (F2) flowing to the load device 4 side based on the difference between the water pressure on the inlet side and the water pressure on the outlet side. As with the heat source system 1 described above, this control device 16 can also reduce the number and types of sensors to be installed, and improve convenience during start-up and operation.

[0053] Furthermore, the heat source system 1 can execute both the process for determining the load flow rate (F2) described above and the process for controlling the bypass valve 2 described in the first embodiment. That is, the heat source unit 3 can be configured as a control device 16 that executes either the process for controlling the bypass valve 2 or the process for determining the load flow rate (F2), or a configuration that executes both the process for controlling the bypass valve 2 and the process for determining the load flow rate (F2).

[0054] The control device 16 may also be configured to execute either the process of controlling the bypass valve 2 or the process of determining the load flow rate (F2), or to execute both the process of controlling the bypass valve 2 and the process of determining the load flow rate (F2).

[0055] (Third embodiment) In the third embodiment, the configuration for acquiring the pressure on the inlet side of the heat source unit 3 in the simplex pump type heat source system 1 is different from the first and second embodiments. As shown in Figure 2, the heat source system 1 of this embodiment differs from the first and second embodiments described above in that it does not have an inlet pressure gauge 17 (see Figure 1), and is configured to obtain the pressure of the water flowing through the return pipe 6 from the control pressure set in the expansion tank 8.

[0056] Specifically, the control device 16 constituting the heat source system 1 is connected to the expansion tank 8 as described in the first embodiment, and is capable of controlling the expansion tank 8 to apply pressure to the water flowing through the return pipe 6. In other words, the control device 16 knows either the pressure applied from the expansion tank 8 to the water flowing through the return pipe 6, or a control value that can identify that pressure.

[0057] At this time, since the outlet of the expansion tank 8 is connected to the return pipe 6, it can be considered that the pressure applied to the water flowing through the return pipe 6 from the expansion tank 8 is substantially the same as the pressure of the water flowing through the return pipe 6.

[0058] Therefore, the control device 16 acquires or determines the pressure of the water flowing through the return pipe 6 from the control pressure set in the expansion tank 8, and based on the difference between that control pressure and the pressure detected by the water side outlet pressure gauge 14, which is the outlet side pressure gauge, performs at least one or both of the processes of controlling the bypass valve 2 described in the first embodiment and the process of calculating the load flow rate (F2) described in the second embodiment.

[0059] This makes it possible to control the bypass valve 2 and determine the load flow rate (F2) without installing an inlet pressure gauge 17, reducing the number and types of sensors to be installed and improving convenience during start-up and operation.

[0060] The heat source unit 3 used in the heat source system 1 also includes a water-refrigerant heat exchanger 9 and a control device 16 that executes a process to determine the load flow rate (F2) flowing to the load device 4 side based on the difference between the water pressure on the inlet side and the water pressure on the outlet side of the water-refrigerant heat exchanger 9. As with the heat source system 1 described above, this heat source unit 3 also makes it possible to reduce the number and types of sensors to be installed, and to improve convenience during start-up and operation.

[0061] Furthermore, the control device 16 that controls the heat source system 1 executes a process to determine the load flow rate (F2) flowing to the load device 4 side based on the difference between the water pressure on the inlet side and the water pressure on the outlet side of the water-refrigerant heat exchanger 9. As with the heat source system 1 described above, this control device 16 can also reduce the number and types of sensors to be installed, and improve convenience during start-up and operation.

[0062] (Fourth embodiment) In the fourth embodiment, an example will be described in which the load flow rate (F12, see FIG. 3) is calculated based on the differential pressure between the inlet and outlet pressures of the heat source unit 3 and the resistance coefficient of the free bypass pipe 20 (see FIG. 3) in a duplex pump type heat source system 1 (see FIG. 3). Note that components common to each embodiment will be described with the same reference numerals. Here, the duplex pump type may be rephrased as, for example, a secondary pump type.

[0063] 3, the heat source system 1 of this embodiment includes a heat source unit 3, a load device 4, a water supply pipe 5, a water return pipe 6, an inlet pressure gauge 17, a water outlet pressure gauge 14 corresponding to the outlet pressure gauge, and a control device 16. A water supply header 21 is provided in the water supply pipe 5 between the heat source unit 3 side and the load device 4 side, and a water return header 22 is provided in the water return pipe 6 between the heat source unit 3 side and the load device 4 side.

[0064] The water supply header 21 includes an upstream header 23 located on the heat source unit 3 side, a downstream header 24 located on the load device 4 side, one or more secondary pumps 25 provided between the upstream header 23 and the downstream header 24, and a control valve 26 that circulates excess water back to the upstream header 23. This secondary pump 25 is controlled by an inverter (not shown). This configuration, in which a pump is provided on each of the heat source unit 3 side and the load device 4 side, is called a dual pump system.

[0065] The operation of this type of double pump system is well known and will not be explained in detail, but the water sent from the heat source unit 3 side is stored in the upstream header 23, and the water stored in the upstream header 23 is sent to the load device 4 side by the secondary pump 25, and the water that has passed through the load device 4 is returned to the heat source unit 3 via the return header 22.

[0066] In the case of the duplex pump system, a free bypass pipe 20 is provided that connects a portion of the water supply pipe 5 that is closer to the heat source unit 3 than the water supply header 21 and a portion of the water return pipe 6 that is closer to the heat source unit 3 than the water return header 22. This free bypass pipe 20 is a piping member that does not have a valve, and is configured such that, as shown by the outline arrow, if the pressure of the water flowing in the water supply pipe 5 is higher than the pressure of the water flowing in the water return pipe 6, water flows from the water supply pipe 5 to the water return pipe 6, and if the pressure of the water flowing in the water supply pipe 5 is lower than the pressure of the water flowing in the water return pipe 6, water flows from the water return pipe 6 to the water supply pipe 5.

[0067] As explained in the second embodiment above, the total amount of water sent from the heat source units 3 side can be considered to be the sum of the chiller flow rates in each of the operating heat source units 3. Since there is no valve, the amount of water flowing through the free bypass pipe 20 can be calculated from the difference in water pressure between the water supply pipe 5 side and the water return pipe 6 side and the resistance coefficient of the free bypass pipe 20. Hereinafter, the total amount of water sent from the heat source units 3 side will be referred to as the leakage water amount (F11), and the amount of water flowing through the free bypass pipe 20 will be referred to as the free bypass flow rate (F13).

[0068] At this time, the free bypass flow rate (F13) is calculated by a general method based on Bernoulli's theorem, so a detailed explanation will be omitted, but it can be calculated by multiplying the flow velocity calculated from the difference in water pressure between the water supply pipe 5 side and the water return pipe 6 side by the cross-sectional area of the free bypass pipe 20, and then taking into account a resistance coefficient determined by the mechanical characteristics of the free bypass pipe 20, etc.

[0069] The load flow rate (F12) can be calculated by subtracting the free bypass flow rate (F13) from the total water volume (F11) when water flows from the water supply pipe 5 to the return pipe 6, and by adding the free bypass flow rate (F13) to the total water volume (F11) when water flows from the return pipe 6 to the water supply pipe 5.

[0070] In this way, the control device 16 can determine the load flow rate (F12) based on the differential pressure between the pressure on the inlet side and the pressure on the outlet side of the heat source unit 3 and the resistance coefficient of the free bypass pipe 20. As a result, as explained in the second embodiment, conventionally provided flow meters, thermometers, etc. are no longer necessary, and the types and number of sensors to be installed can be reduced.

[0071] In addition, since the inlet pressure gauge 17 is installed in the heat source unit 3, it is possible to avoid unexpected troubles, etc., and it is also possible to obtain effects such as improving convenience during start-up and operation.

[0072] The heat source unit 3 used in the heat source system 1 also includes a water-refrigerant heat exchanger 9 and a control device 16 that executes a process to determine the load flow rate (F12) flowing to the load device 4 side based on the difference between the water pressure on the inlet side and the water pressure on the outlet side. As with the heat source system 1 described above, this heat source unit 3 also makes it possible to reduce the number and types of sensors to be installed, and to improve convenience during start-up and operation.

[0073] Furthermore, the control device 16 that controls the heat source system 1 executes a process to calculate the load flow rate (F12) flowing to the load device 4 side based on the difference between the water pressure on the inlet side and the water pressure on the outlet side. As with the heat source system 1 described above, this control device 16 can also reduce the number and types of sensors to be installed, and improve convenience during start-up and operation.

[0074] (Fifth embodiment) In the fifth embodiment, in a duplex pump type heat source system 1, the configuration for acquiring the pressure on the inlet side of the heat source unit 3 is different from that of the fourth embodiment. Note that the same reference numerals will be used to denote the same components as in the fourth embodiment.

[0075] As shown in Fig. 4, the heat source system 1 of this embodiment differs from the fourth embodiment in that it does not have an inlet pressure gauge 17 (see Fig. 3), and the pressure of the water flowing through the return pipe 6 is obtained from the control pressure set in the expansion tank 8. In other words, the heat source system 1 of this embodiment is a dual pump system that executes the same processing as the third embodiment.

[0076] The control device 16 that constitutes the heat source system 1 is connected to the expansion tank 8, and is capable of controlling the pressure applied to the expansion tank 8 with respect to the water flowing through the return pipe 6. In other words, the control device 16 knows either the pressure applied from the expansion tank 8 to the water flowing through the return pipe 6, or a control value that can identify that pressure.

[0077] At this time, since the outlet of the expansion tank 8 is connected to the return water pipe 6, the pressure applied from the expansion tank 8 to the water flowing through the return water pipe 6 can be considered to be the pressure of the water flowing through the return water pipe 6. Then, the control device 16 acquires or identifies the pressure of the water flowing through the return water pipe 6 from the control pressure set in the expansion tank 8, and executes a process to calculate the load flow rate (F12) flowing to the load device 4 side described in the fourth embodiment based on the difference between the control pressure and the pressure detected by the water side outlet pressure gauge 14, which is the outlet side pressure gauge.

[0078] This makes it possible to determine the load flow rate (F12) without installing an inlet pressure gauge 17, reducing the number and types of sensors to be installed and improving convenience during start-up and operation.

[0079] The heat source unit 3 used in the heat source system 1 also includes a water-refrigerant heat exchanger 9 and a control device 16 that executes processing to calculate the load flow rate (F12) flowing to the load device 4 side based on the difference between the control pressure of the expansion tank 8 and the water pressure detected by the outlet pressure gauge, that is, based on the difference between the water pressure on the inlet side and the water pressure on the outlet side of the water-refrigerant heat exchanger 9. As with the heat source system 1 described above, this heat source unit 3 can also reduce the number and types of sensors to be installed, and improve convenience during start-up and operation.

[0080] Furthermore, the control device 16 that controls the heat source system 1 executes a process to calculate the load flow rate (F2) flowing to the load device 4 side based on the difference between the water pressure on the inlet side and the water pressure on the outlet side of the water-refrigerant heat exchanger 9. As with the heat source system 1 described above, this control device 16 can also reduce the number and types of sensors to be installed, and improve convenience during start-up and operation.

[0081] (Sixth embodiment) In the sixth embodiment, the arrangement of the bypass pipe 7 or the free bypass pipe 20 is different from that of the other embodiments.

[0082] In the first embodiment and the like, an example was shown in which the bypass pipe 7 was provided outside the heat source machine 3 in the simplex pump system, but as shown in Example 1 of Built-in Piping in Figure 5, the bypass pipe 7 and bypass valve 2 can be configured to be located inside the heat source machine 3. This allows the bypass valve 2 to be prepared by the manufacturer of the heat source machine 3, preventing the occurrence of the above-mentioned unexpected trouble. Furthermore, because the bypass pipe 7 is built into the heat source machine 3, piping can be used as specified, allowing the heat source machine 3 and heat source system 1 to be appropriately controlled, and the work of installing the bypass pipe 7 on the load device 4 side is no longer necessary, thereby reducing installation costs. The heat source unit 3 incorporating the bypass pipe 7 may be a plurality of units, or may be only a representative unit.

[0083] Furthermore, as shown as a second example of built-in piping in Fig. 5, in the duplex pump system, the free bypass pipe 20 can be configured to be located inside the heat source machine 3. This allows the manufacturer of the heat source machine 3 to prepare the free bypass pipe 20, and since mechanical elements such as the cross-sectional area and resistance coefficient can be reliably determined, it becomes possible to properly perform calculations to determine the load flow rate, allowing the heat source system 1 to be operated properly, and also reducing installation costs because there is no need to install the free bypass pipe 20 on the load device 4 side. The heat source unit 3 incorporating the free bypass pipe 20 may be a plurality of units, or may be only a representative unit.

[0084] (Other embodiments) In the embodiment, an example is shown in which the control device 16 is built into the heat source machine 3, but the control device 16 can also be attached to the surface of the heat source machine 3, installed near the heat source machine 3, or installed in a remote location such as a control room.

[0085] In the embodiment, an example has been shown in which the inlet pressure gauge 17 is built into the representative heat source unit 3, but the inlet pressure gauge 17 can also be provided in all installed heat source units 3 or in multiple installed heat source units 3. In other words, it is sufficient that one or more inlet pressure gauges 17 are provided. In this case, when multiple heat source units 3 are provided with inlet pressure gauges 17, they can be configured to communicate with the control device 16 via the unit controller 15, for example.

[0086] In the embodiment, an example has been shown in which the inlet side pressure gauge 17 is built into the heat source machine 3, but if the inlet pump 10 is provided outside the heat source machine 3, the inlet side pressure gauge 17 will also be provided outside the heat source machine 3. In that case, if the inlet pump 10 provided externally already has a pressure gauge, the pressure gauge can be used as the inlet side pressure gauge 17.

[0087] In the embodiment, an example is shown in which the control pressure is determined based on a control command from the control device 16, but if a pressure gauge is provided in the expansion tank 8, the detected value of the pressure gauge can be obtained as the control pressure set in the expansion tank 8.

[0088] Although several embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the inventions and their equivalents as defined in the claims.

Claims

1. A single-pump heat source system in which a plurality of heat source units each having a water-refrigerant heat exchanger are connected to a load device by a common water supply pipe and a common water return pipe, and one inlet pump is provided for each heat source unit, an inlet side pressure gauge that is provided inside the heat source unit on an inlet side where water flows into the water-refrigerant heat exchanger from the return water pipe, and that detects the pressure of the water flowing through the return water pipe upstream of the inlet pump that sends water to the water-refrigerant heat exchanger; an outlet pressure gauge that is provided inside the heat source device at an outlet side where water flows out from the water-refrigerant heat exchanger to the water supply pipe, and that detects the pressure of the water flowing through the water supply pipe; a control device that is provided in the heat source machine closest to the load device in the water flow, and that executes processing to control a bypass valve that is provided in a bypass pipe that connects the water supply pipe and the return pipe in parallel with the load device, without using a flow meter, based on the difference between the inlet pressure detected by the inlet pressure gauge and the outlet pressure detected by the outlet pressure gauge of the heat source machine during operation; A heat source system comprising:

2. A heat source machine used in a heat source system in which a plurality of heat source machines and load devices are connected by a common water supply pipe and a common return pipe, a water-refrigerant heat exchanger that exchanges heat between water and a refrigerant; a control device that executes a process of controlling a bypass valve provided in a bypass pipe connecting the water supply pipe and the water return pipe in parallel with the load device, without using a flow meter, based on a difference between the water pressure on an inlet side where water flows into the water-refrigerant heat exchanger from the water return pipe inside the heat source unit closest to the load device in the water flow and the water pressure on an outlet side where water flows out from the water-refrigerant heat exchanger to the water supply pipe; A heat source machine characterized by comprising:

3. A control device for controlling a heat source system in which a plurality of heat source devices each having a water-refrigerant heat exchanger and a load device are connected by a common water supply pipe and a common return pipe, A control device characterized by performing a process to control a bypass valve provided in a bypass pipe connecting the water supply pipe and the return pipe in parallel with the load device, without using a flow meter, based on the difference between the water pressure on the inlet side where water flows into the water-refrigerant heat exchanger from the return pipe inside the heat source unit closest to the load device and the water pressure on the outlet side where water flows out from the water-refrigerant heat exchanger into the water supply pipe.

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