Heat Source System

Abstract

To provide a heat source system, a heat source machine and a control device capable of reducing the types and number of sensors to be installed and improving convenience at start-up and during an operation.SOLUTION: A heat source system includes: an inlet side pressure gauge that is provided on an inlet side on which water flows from a water return pipe into a water refrigerant heat exchanger and detects pressure of the water flowing in the water return pipe on the upstream side of an inlet pump for sending the water to the water refrigerant heat exchanger; an outlet side pressure gauge that is provided on an outlet side on which the water flows out from the water refrigerant heat exchanger to a water feed pipe and detects pressure of the water flowing in the water feed pipe; and a control device that executes processing for calculating a load flow rate flowing on a load device side on the basis of a difference between the pressure on the inlet side detected by the inlet side pressure gauge and the pressure on the outlet side detected by the outlet side pressure gauge, an opening of a bypass valve provided in a bypass pipe connecting the water feed pipe and the water return pipe in parallel with a load device and mechanical characteristics of the bypass valve.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

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

[0003] Such heat source systems are configured as a single pump system in which a pump is provided only on the heat source unit side, or as a dual pump system in which a pump is also provided on the load device side.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] JP 2006-38379 A [Patent Document 2] JP 2014-35090 A Summary of the Invention [Problem to be solved by the invention]

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

[0006] Therefore, a heat source system that can reduce the number and types of sensors to be installed and can improve convenience during start-up and operation is proposed. M provide. [Means for solving the problem]

[0007] The heat source system of one embodiment is a single-pump type heat source system in which a heat source unit having a water-refrigerant heat exchanger is connected to a load device by a water supply pipe and a water return pipe, and one inlet pump is provided for each heat source unit, and is characterized by comprising: an inlet side pressure gauge provided on the inlet side where water flows into the water-refrigerant heat exchanger from the water return pipe and detects the pressure of water flowing through the water return pipe upstream of the inlet pump that sends water to the water-refrigerant heat exchanger; an outlet side pressure gauge provided on the outlet side where water flows out of the water-refrigerant heat exchanger into the water supply pipe and detects the pressure of water flowing through the water supply pipe; and a control device that executes a process to calculate the load flow rate flowing to the load device based on the difference between the inlet side pressure detected by the inlet side pressure gauge and the outlet side pressure detected by the outlet side pressure gauge, the opening degree of a bypass valve provided in a bypass pipe that connects the water supply pipe and the water return pipe in parallel to the load device, and the mechanical characteristics of the bypass valve. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of a heat source system of a single pump type in a first embodiment and a second embodiment; [Diagram 2] FIG. 13 is a schematic diagram showing another configuration of a single-pump heat source system according to the third embodiment. [Diagram 3] FIG. 13 is a diagram showing a schematic configuration of a heat source system using a double pump in a fourth embodiment. [Figure 4] FIG. 13 is a schematic diagram showing another configuration of a heat source system of a double pump type in the fifth embodiment. [Diagram 5] FIG. 13 is a diagram showing a schematic piping configuration of a heat source system according to a sixth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Several embodiments will be described below. The details will be described later, but 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 of these. For the sake of simplicity, the heat source systems of the respective embodiments are given 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 pressure difference between the inlet side pressure and the outlet side pressure of a heat source unit 3 (see FIG. 1) in a simple pump type heat source system 1 (see FIG. 1). Here, the simple pump type may be rephrased as, for example, a primary pump type.

[0011] As shown in Fig. 1, the heat source system 1 includes a heat source machine 3, a load device 4, a water supply pipe 5 and a return pipe 6 for circulating water between the heat source machine 3 and the load device 4, and is configured such that 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 conditioners for air conditioning buildings and cleaning devices and drying devices installed in factories, while water from the load device 4 is returned to the heat source machine 3 via the return pipe 6. Note that in Fig. 1, the direction of water flow is conveniently indicated by hollow 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 for applying 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, from two to a dozen, are installed based on the required specifications and to enable backup in the event of a breakdown. 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 piping 11 through which water flows into the water-refrigerant heat exchanger 9, a water-side outlet pressure gauge 14 provided in an outlet piping 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 partitioned 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. As the water-refrigerant heat exchanger 9, one capable of generating so-called hot water, one capable of generating so-called cold water, or one capable of generating both hot water and cold water may be appropriately used depending on 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. This inlet pump 10 adjusts the water flowing through the return pipe 6 to a predetermined pressure before sending it to the water-refrigerant heat exchanger 9, and 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 method of sending water to the load device 4 by a pump provided in the heat source unit 3 is called a single pump method.

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

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

[0018] The unit controller 15 individually controls the heat source units 3, and controls each heat source unit 3 by, for example, executing a process to calculate the flow rate of water flowing through the water-refrigerant heat exchanger 9 (hereinafter referred to as 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. This 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 heat source units 3, which are installed, and outputs control commands for controlling the heat source system 1 to each heat source unit 3, and acquires information indicating the operating state, such as the above-mentioned chiller flow rate, from each heat source unit 3. The control device 16 is also connected directly to the load device 4 or indirectly via a control unit of the load device 4, and is capable of acquiring information indicating the operating state of the load device 4. Hereinafter, the heat source unit 3 with the built-in control device 16 will be referred to as the representative unit for convenience.

[0020] The control device 16 is also connected to the bypass valve 2 and the expansion tank 8, and can perform a process of adjusting the opening of the bypass valve 2 provided in the bypass pipe 7, and a process of acquiring the pressure (control pressure) applied from the expansion tank 8 to the water flowing through the return pipe 6. Note that 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 specify the pressure value to be set.

[0021] The heat source unit 3 provided with the control device 16 is 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 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 pipe 6.

[0022] In the present embodiment, the inlet pressure gauge 17 is built into the representative heat source unit 3. 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 the water branched off from the return water pipe 6 flows in downstream of the representative unit, and the water flows out to 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-mentioned configuration will be described. The inlet pump 10 is for sending water at a predetermined pressure to the water-refrigerant heat exchanger 9, and also functions as a drive source for sending water to the load device 4 side as described above. At this time, if the shutoff valve 4a on the load device 4 side is closed for reasons such as the load device 4 being stopped operating, 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 shutoff operation state, which may cause the temperature to rise and lead to breakdowns or the generation of noise and vibrations. 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 provided, and for example, the bypass valve 2 was PID controlled so that the water flow would be appropriate 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 itself be controlled based on the differential pressure, there is a problem that is difficult to solve by only obtaining the differential pressure when actually operating the heat source system 1. As is well known, the smaller the applied pressure, the easier it is for water to boil, so when the pressure of the water flowing through the return pipe 6 becomes smaller than a reference value such as atmospheric pressure, cavitation or the like occurs, which can cause a breakdown.

[0027] For this reason, 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 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 are increased, not only will costs simply increase, but each sensor will need to be adjusted, requiring a great deal of effort not only at the start-up but also during operation of the heat source system 1. Furthermore, since sensors to be installed in piping are generally installed by the owner, there is a risk that the installed sensors may differ from the specifications, which may cause malfunctions from the perspective of the heat source unit 3, resulting in unexpected trouble.

[0029] Therefore, as described above, the heat source system 1 has 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 an 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 a differential pressure gauge that was previously installed. In addition, 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 improve.

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

[0032] In addition, in the heat source system 1, the inlet pressure gauge 17 is provided in 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 sensor being different from the specifications as in the past. Furthermore, since there is no need to extend wiring to the piping side as in the case of a conventional differential pressure gauge, the installation costs can 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 unit 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 itself, 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 comprises an inlet side pressure gauge 17 that detects the pressure of water flowing through the return pipe 6 upstream of the inlet pump 10, 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 a bypass valve 2 provided in a 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 side pressure detected by the inlet side pressure gauge 17 and the outlet side pressure detected by the outlet side 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 a differential pressure gauge as was previously provided. In addition, the inlet side pressure gauge 17 can also be used to monitor the pressure on the return pipe 6 side, making it possible to reduce the number and types of sensors to be installed.

[0036] In addition, since the bypass valve 2 is controlled based on the differential pressure, the occurrence of the shutoff 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 unit 3, the manufacturer of the heat source unit 3 will prepare 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 includes a water-refrigerant heat exchanger 9 and a control device 16 that 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 detected by the inlet pressure gauge 17 and the water pressure detected by the outlet pressure gauge, that is, based on the pressure difference between the inlet side and the outlet side of the heat source unit 3 or the water-refrigerant heat exchanger 9. With this heat source unit 3, as with the heat source system 1 described above, it is possible to reduce the number and types of sensors to be installed, and to improve convenience during start-up and operation. In addition, it is possible to shorten the construction period and reduce costs when constructing 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 calculating the amount of water flowing to the load device 4 side in a heat source system 1 of a single pump type will be described. Note that since the configuration of the heat source system 1 is common to the first embodiment, the description will be given with reference to FIG.

[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, etc.

[0041] Now, 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, 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 for convenience, 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 FIG. 1). In addition, 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 for convenience.

[0042] For this reason, 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 for detecting 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 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.

[0044] First, the control device 16 obtains the total amount of water supplied from the heat source unit 3. Hereinafter, the total amount of water supplied from the heat source unit 3 is referred to as the total flow rate (F1. See FIG. 1). At this time, the total flow rate (F1) is considered to be the sum of the amount of water (chiller flow rate) supplied from each heat source unit 3 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 obtain the total flow rate (F1).

[0046] Next, the control device 16 determines the amount of water flowing through the bypass pipe 7 from the opening degree 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). Hereinafter, the amount of water that can pass through the bypass valve 2 is f, the valve opening degree of the bypass valve 2 is v, the flow rate when the bypass valve 2 is fully open is Cv, the range ability indicating the adjustment range is r, the density of water is ρ, the gravitational acceleration is G, and the pressure difference between the inlet side and the outlet side 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) If the total flow rate (F1) and the bypass flow rate (F3) are determined in this manner, 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 determined 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 side pressure gauge 17 is provided in the heat source unit 3, the manufacturer of the heat source unit 3 will prepare the inlet side pressure gauge 17, which makes it possible to avoid the unexpected troubles described above, etc., thereby improving convenience during start-up and operation.

[0051] The heat source unit 3 used in the heat source system 1 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. With this heat source unit 3, like the heat source system 1 described above, it is possible to reduce the number and types of sensors to be installed, and to improve convenience during start-up and operation. It is also possible to shorten the construction period and reduce costs when constructing 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 to have 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 to execute both the process for controlling the bypass valve 2 and the process for determining the load flow rate (F2).

[0054] In addition, the control device 16 can be configured to execute either a process for controlling the bypass valve 2 or a process for calculating the load flow rate (F2), or to execute both a process for controlling the bypass valve 2 and a process for calculating the load flow rate (F2).

[0055] Third embodiment In the third embodiment, in a heat source system 1 of a simple pump type, the configuration for acquiring the pressure on the inlet side of the heat source unit 3 is different from the first and second embodiments. As shown in Figure 2, the heat source system 1 of this embodiment is different from the first and second embodiments described above in that it does not have an inlet side pressure gauge 17 (see Figure 1), and the pressure of the water flowing through the return pipe 6 is obtained 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 capable of identifying 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 identifies 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, executes 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 side pressure gauge 17, thereby 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 includes a water-refrigerant heat exchanger 9 and a control device 16 that executes a process to calculate a 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 can also reduce the number and types of sensors to be installed, and improve convenience during start-up and operation.

[0061] 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.

[0062] (Fourth embodiment) In the fourth embodiment, an example will be described in which a load flow rate (F12, see FIG. 3) is calculated based on the pressure difference 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). Configurations 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 and a return water pipe 6, an inlet side pressure gauge 17, a water side outlet pressure gauge 14 corresponding to the outlet side pressure gauge, and a control device 16. In addition, a water supply side 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 return water side header 22 is provided in the return water 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 for circulating excess water 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 dual pump system is well known and will not be explained in detail, but the water sent from the heat source unit 3 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 double 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 side header 21 and a portion of the water return pipe 6 that is closer to the heat source unit 3 than the water return side header 22. This free bypass pipe 20 is a piping member that is not provided with a valve, and is configured such that, as shown by the outlined arrow, if the pressure of the water flowing through the water supply pipe 5 is higher than the pressure of the water flowing through the water return pipe 6, the water flows from the water supply pipe 5 to the water return pipe 6, whereas if the pressure of the water flowing through the water supply pipe 5 is lower than the pressure of the water flowing through the water return pipe 6, the 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 unit 3 side can be considered to be the sum of the chiller flow rates in each heat source unit 3 in operation. 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 unit 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 and will not be described in detail here; however, 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 adding a resistance coefficient determined by the mechanical characteristics of the free bypass pipe 20, etc.

[0069] The load flow rate (F12) can be obtained by subtracting the free bypass flow rate (F13) from the total water volume (F11) when water flows from the 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 supply pipe 5.

[0070] In this way, the control device 16 can obtain 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 described in the second embodiment, the flowmeter, thermometer, and the like that have been conventionally provided become unnecessary, and the types and number of sensors to be installed can be reduced.

[0071] In addition, since the inlet side 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 other benefits such as improving convenience during start-up and operation.

[0072] The heat source unit 3 used in the heat source system 1 includes a water-refrigerant heat exchanger 9 and a control device 16 that 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 heat source unit 3 can also reduce the number and types of sensors to be installed, and can improve convenience during start-up and operation.

[0073] Furthermore, the control device 16 that controls the heat source system 1 executes a process for calculating 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 dual-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 configuration common to the fourth embodiment will be described with the same reference numerals.

[0075] As shown in Fig. 4, the heat source system 1 of this embodiment differs from the above-described fourth embodiment in that it does not include 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 process as the above-described third embodiment.

[0076] The control device 16 constituting the heat source system 1 is connected to the expansion tank 8, and is capable of controlling the application of pressure to the expansion tank 8 with respect to the water flowing through the return pipe 6. In other words, the control device 16 is aware of either the pressure applied from the expansion tank 8 to the water flowing through the return pipe 6, or a control value capable of identifying 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 of calculating 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 includes a water-refrigerant heat exchanger 9 and a control device 16 that executes a process 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. With this heat source unit 3, like the above-described heat source system 1, it is possible to reduce the number and types of sensors to be installed and to 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 unit 3 in the simplex pump system, but as shown in the first example of built-in piping in Fig. 5, the bypass pipe 7 and the bypass valve 2 can be configured to be disposed inside the heat source unit 3. This allows the manufacturer of the heat source unit 3 to prepare the bypass valve 2, and the occurrence of the above-mentioned unexpected troubles can be prevented. In addition, since the bypass pipe 7 is built into the heat source unit 3, piping can be used as specified, so the heat source unit 3 and the heat source system 1 can be appropriately controlled, and the work of arranging the bypass pipe 7 on the load device 4 side is no longer necessary, which can reduce 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] 5 as a second example of built-in piping, in the duplex pump system, the free bypass pipe 20 can be arranged inside the heat source unit 3. This allows the manufacturer of the heat source unit 3 to prepare the free bypass pipe 20, and since mechanical elements such as the cross-sectional area and resistance coefficient can be reliably grasped, it becomes possible to properly perform calculations to obtain the load flow rate, allowing the heat source system 1 to be operated properly, and since the task of installing the free bypass pipe 20 on the load device 4 side is no longer necessary, the installation cost can be reduced. 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 unit 3, but the control device 16 can also be attached to the surface of the heat source unit 3, installed in the vicinity of the heat source unit 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 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 the inlet pressure gauges 17 are provided in multiple heat source units 3, they can be configured to communicate with the control device 16 via the unit controller 15, for example.

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

[0087] In the embodiment, an example has been 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 detection 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 implemented 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 in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0089] In the drawing, 1 is a heat source system, 2 is a bypass valve, 3 is a heat source unit, 4 is a load device, 5 is a water supply pipe, 6 is a return pipe, 7 is a bypass pipe, 8 is an expansion tank, 9 is a water-refrigerant heat exchanger, 10 is an inlet pump, 14 is a water side outlet pressure gauge (outlet side pressure gauge), 16 is a control device, 17 is an inlet side pressure gauge, and 20 is a free bypass pipe.

Claims

1. A heat source system of a single pump type, in which a heat source unit having a water-refrigerant heat exchanger is connected to a load device by a water supply pipe and a water return pipe, and one inlet pump is provided for one heat source unit, an inlet pressure gauge provided on an inlet side where water flows into the water-refrigerant heat exchanger from the return pipe, the inlet pressure gauge being arranged upstream of an inlet pump that sends water to the water-refrigerant heat exchanger; and an outlet pressure gauge provided on an outlet side where water flows out from the water-refrigerant heat exchanger to the water supply pipe and detecting a pressure of the water flowing through the water supply pipe; a control device that executes a process of calculating a load flow rate flowing to the load device side based on a difference between an inlet side pressure detected by the inlet side pressure gauge and an outlet side pressure detected by the outlet side pressure gauge, an opening degree of a bypass valve provided in a bypass pipe that connects the water supply pipe and the return pipe in parallel with the load device, and a mechanical characteristic of the bypass valve; A heat source system comprising:

2. A heat source system of a single pump type, in which a heat source unit having a water-refrigerant heat exchanger is connected to a load device by a water supply pipe and a water return pipe, and one inlet pump is provided for one heat source unit, an outlet pressure gauge provided on an outlet side where water flows out from the water-refrigerant heat exchanger to the water supply pipe and detecting a pressure of the water flowing through the water supply pipe; a control device that executes a process of calculating a load flow rate flowing to the load device side based on a difference between a control pressure set in an expansion tank that applies a predetermined pressure to the water flowing through the return pipe and the outlet side pressure detected by the outlet side pressure gauge, an opening degree of a bypass valve provided in a bypass pipe that connects the water supply pipe and the return pipe in parallel with the load device, and a mechanical characteristic of the bypass valve; A heat source system comprising:

3. A heat source system of a dual pump type, in which a heat source unit having a water-refrigerant heat exchanger is connected to a load device by a water supply pipe and a water return pipe, one inlet pump is provided for each heat source unit, and a secondary pump is provided on the water supply pipe, an inlet pressure gauge provided on an inlet side where water flows into the water-refrigerant heat exchanger from the return pipe, the inlet pressure gauge detecting a 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 provided on an outlet side where water flows out from the water-refrigerant heat exchanger to the water supply pipe and detecting a pressure of the water flowing through the water supply pipe; a control device that executes a process of calculating a load flow rate flowing to the load device side based on a difference between an inlet side pressure detected by the inlet side pressure gauge and an outlet side pressure detected by the outlet side pressure gauge, and a resistance coefficient of a free bypass pipe that is connected in parallel with the load device between the water supply pipe and the return pipe; A heat source system comprising:

4. A heat source system of a dual pump type, in which a heat source unit having a water-refrigerant heat exchanger is connected to a load device by a water supply pipe and a water return pipe, one inlet pump is provided for each heat source unit, and a secondary pump is provided on the water supply pipe, an outlet pressure gauge provided on an outlet side where water flows out from the water-refrigerant heat exchanger to the water supply pipe and detecting a pressure of the water flowing through the water supply pipe; a control device that executes a process of calculating a load flow rate flowing to the load device side based on a difference between a control pressure set in an expansion tank that applies a predetermined pressure to the water flowing through the return pipe and the outlet side pressure detected by the outlet side pressure gauge, and a resistance coefficient of a free bypass pipe that connects the water supply pipe and the return pipe in parallel with the load device; and A heat source system comprising:

5. 5. The heat source system according to claim 1, wherein the heat source unit is provided with a pipe connecting the water supply pipe and the return pipe in parallel with the load device.

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