JP5476835B2 - Air conditioning system - Google Patents

Description

  In the present invention, the cold / hot water subjected to heat exchange by a plurality of heat sources is fed to an air conditioner via a forward header by a plurality of heat source pumps controlled to rotate at an inverter frequency, and the cold / hot water subjected to heat exchange by the air conditioner. It is related with the air-conditioning system which circulates to the said heat source through a return header.

  Chilled / hot water heat-exchanged by a plurality of heat sources is sent to the air conditioner via a forward header by a plurality of heat source pumps controlled to rotate at the inverter frequency, and the chilled / hot water heat-exchanged by the air conditioner is returned to the header. Patent Document 1 discloses a technical disclosure of a control apparatus for an air conditioning system that optimally controls the pressure of the forward header based on the flow rate of cold / hot water in an air conditioning system that circulates to the heat source.

  FIG. 9 is a functional block diagram showing a configuration example of a conventional central air-conditioning system using a direct delivery system. For simplification of explanation, the configuration of two heat sources and heat source pumps is shown, but the same control can be achieved even if there are three or more heat sources.

  The cold / hot water heat-exchanged by the heat source 1 and the heat source 2 is sent to the air conditioner 4 through the forward header 3. The air conditioner 4 exchanges the necessary amount of heat, and the heat-exchanged cold / hot water circulates and returns to the heat sources 1 and 2 through the return header 5.

  The water supply amount of the heat source 1 and the heat source 2 is operated by the heat source pumps 6 and 7. The rotation speeds of the heat source pumps 6 and 7 are controlled by the frequency of the inverters 8 and 9. The frequencies of the inverters 8 and 9 are adjusted by operating amounts MV1 and MV2 from the heat source control device 40.

  The cold / hot water from the air conditioner 4 is measured by the recirculation amount sensor 10, and the flow rate measurement value PV <b> 1 is input to the heat source control device 40. The pressure in the forward header 3 is measured by the pressure sensor 11, and the pressure measurement value PV <b> 2 is input to the heat source control device 40.

  The forward header 3 and the return header 5 are connected by a bypass pipe 12, and a bypass valve 13 is inserted in the middle. The pressure controller 14 adjusts the opening degree of the bypass valve 13 so that the measured value PV2 of the pressure sensor 11 becomes a predetermined value. This controller 14 performs control to open the bypass valve 13 and release the pressure to the return header 5 side when the pressure increases excessively in order to prevent an abnormal increase in the pressure of the forward header 3.

  The temperature of the forward header 3 is measured by the temperature sensor 15, and the measured value PV <b> 3 is input to the heat source control device 40. Similarly, the temperature of the return header 5 is measured by the temperature sensor 16, and the measured value PV <b> 4 is input to the heat source control device 40.

  In the heat source control device 40, the calorific value calculation means 41 inputs the flow rate measurement value PV1 of the recirculation amount, the temperature measurement value PV3 of the forward header 3 and the temperature measurement value PV4 of the return header 5, and the amount of heat exchanged by the air conditioner 4 Q is calculated.

The amount of heat exchanged by the air conditioner 4 is assumed to be zero.
Amount of heat Q = (return header temperature PV4−outhead header temperature PV3) × reflux amount PV1 (formula 1)
Given in. This calorific value calculation value Q is input to the operation number switching means 42.

  When the amount of heat exchanged by the air conditioner 4 increases and exceeds the specification of one heat source, a sufficient air conditioning effect cannot be obtained. The operation number switching means 42 monitors the value of the heat quantity Q, outputs operation commands D1 and D2 to the heat source 1 and the heat source 2, and switches the operation number.

  The operating number switching means 42 activates the second heat source and the heat source pump slightly before the amount of heat required by the air conditioner 4 exceeds the capacity of the heat source to ensure the heat source capacity. Further, when the amount of heat required from the air conditioner side is reduced and the amount of heat can be secured with the capacity of one heat source, the heat source and one heat source pump are stopped. That is, when the required amount of heat is small, energy is saved by stopping the paired heat source and heat source pump and reducing the number of operating units.

  In the case of a system in which the inverters are not attached to the heat source pumps 6 and 7, the heat source pumps are operated at a constant rotation speed at a commercial frequency, so energy saving is only the number control of the heat sources. When the heat source pumps 6 and 7 include the inverters 8 and 9, the pressure control of the forward header 3 is executed by the frequency control of the inverters.

  The pressure controller 43 controls and calculates the deviation between the pressure measurement value PV1 of the pressure sensor 11 and the pressure setting value P1 for ensuring the minimum flow rate of the heat source pump, and sets the manipulated variable MV to the high selector 44 and the MV value distribution means 45. To the inverters 8 and 9 of the heat source pumps 6 and 7.

  In order to secure the passage flow rate of the heat source at the time of starting the system and increasing the pump stage, it is necessary to set the inverter frequency to a certain time (minimum flow rate guarantee time T1), the commercial frequency, or a constant frequency equivalent thereto. After the minimum flow rate guarantee time T1 has elapsed, the process proceeds to constant pressure control.

  The flow rate guarantee means 46 receives the operation commands D1 and D2 information from the operation number switching means 42, and increases the operation amount MV at which the pump flow rate becomes maximum during the minimum flow rate guarantee time T1 at the time of starting and increasing the pump. Output to the selector 44.

  FIG. 10 is a characteristic diagram for explaining the transition of the number of operating heat source pumps and the pressure control operating point. FIG. 10A shows the relationship between the flow rate F and the number of operating heat source pumps. If the hysteresis is omitted, at the pump stepping point P, the single unit operation is switched to the two unit operation at the flow rate F1max or more, and the two unit operation is switched to the single unit operation at the flow rate F1max or less.

  FIG. 10B shows the pressure characteristics of the forward header with respect to the flow rate F, K1 shows the pressure characteristics of one pump, and K2 shows the pressure characteristics of two pumps. A minimum flow rate is set for the heat source to protect the equipment. For this reason, even if an inverter is attached to the heat source pump, it cannot be lowered below the inverter frequency at which the minimum flow rate value can be secured.

  Therefore, the pressure setting value P1 higher than the frequency at which the minimum flow rate value can be obtained must be set as the pressure setting value of the forward header. This pressure set value P1 is given by the pressure P1 at the point A that obtains the maximum flow rate F2max of the pump on the pressure characteristic K2 during operation of the two units.

  Since the pressure setting value of the pressure controller 43 is constant at P1, the pump operating point transitions on a straight line between point A on the pressure characteristic K2 and point B when the flow rate is zero, regardless of the number of operating pumps. To do.

  FIG. 11 is a waveform diagram for explaining the operation amount guarantee operation with respect to the change in the operation state of the heat source pump. 11A shows the operating state of the heat source pump 6, FIG. 11B shows the operating state of the heat source pump 7, FIG. 11C shows the waveform of the operation amount MV1 of the inverter 8 that drives the heat source pump 6, and FIG. The waveform of the manipulated variable MV2 of the inverter 9 that drives

  The system is activated at time t0, and the heat source pump 6 is changed from the stopped state to the operating state. During a period of time T1 from time t0 to time t1, the operation amount MV1 of the inverter 8 that drives the heat source pump 6 is forcibly maintained at 100%.

  When the pump stage is increased at time t2, the heat source pump 7 is changed from the stopped state to the operating state. During a period of time T1 from time t2 to time t3, the operation amount MV1 of the inverter 8 that drives the heat source pump 6 and the operation amount MV2 of the inverter 9 that drives the heat source pump 7 are forcibly maintained at 100%.

  When the pump step-down occurs at time t4, the heat source pump 6 changes from the operating state to the stopped state. In this case, the forced change of the operation amount for the inverter 8 and the inverter 9 is not performed.

FIG. 12 is a functional block diagram showing a configuration example of a conventional central air conditioning system using a secondary pump system. The difference from the configuration of the central air-conditioning system using the direct delivery method in FIG.
(1) The forward header is composed of a primary forward header 31 and a secondary forward header 32, and the bypass conduit 12 between the forward and backward headers is not provided with a control valve.

(2) The control of the inverter 18 that drives the secondary pump 17 that supplies water to the secondary header 32 is independent of the control of the number of heat sources, and is controlled by the pressure control unit 19 that inputs the measured value PV2 of the pressure sensor 11. Control is performed so that the discharge pressure of the secondary forward header 32 is constant. Details of this control system are disclosed in Patent Document 1.

(3) The heat source control device 40 includes two pressure controllers 43a and 43b in which a common pressure set value P1 is set. The controller 43a inputs an operation amount MV11 obtained by controlling and calculating a deviation between the measured value PV5 of the pressure sensor 20 for measuring the discharge pressure of the heat source 1 and the common set value P1 to the high selector 44.

  Similarly, the controller 43b inputs, to the high selector 44, an operation amount MV12 obtained by controlling and calculating a deviation between the measured value PV6 of the pressure sensor 21 that measures the discharge pressure of the heat source 2 and the common set value P1.

(4) The fluid Fa flowing through the bypass pipe 12 from the primary forward header 31 to the return header 5 is a circulating route of cold / hot water by the heat source pump, and the fluid Fb flowing from the return header 5 to the forward header 31 is cold / hot water by the secondary pump 17. It is a circulation route.

  When Fa> Fb, the cold / hot water flowing through the bypass pipe 12 flows in the direction of the arrow Fa. When Fb> Fa, the cold / hot water flows in the direction of the arrow Fb. In the conventional air conditioning system, control is performed so that Fa> Fb.

  Otherwise, the amount of heat (≈ flow rate) to the air conditioner will be insufficient. However, in the air conditioning system, even if cold / hot water is circulated through the bypass pipe, it does not work and is wasted. Here is the point of energy saving.

JP 2003-106731 A

The conventional air conditioning system has the following problems.
(1) In the case of energy saving with a central air conditioning system, there is a known technique called variable pump head control. When the heat source pump is controlled in the variable head range, there is a restriction on the minimum flow rate value of the heat source, so an exception (some heat source devices can control the heat source pump's variable range by directly outputting load information to the controller. Variable range control cannot be performed except for the above).

  In general, since the minimum flow rate is determined by the specifications of the heat source, even if an inverter is installed for energy saving control, the pump should be used so that the total flow rate of the guaranteed minimum flow rate of all heat sources is not lower than the pressure value. It is necessary to control the rotation speed on the side.

  However, it is difficult to determine the optimum pressure setting value P1 that can obtain the minimum flow rate value. As a result, it is difficult to expect a sufficient energy saving effect because a large margin must be taken.

(2) The same fixed time T1 is set as the minimum flow rate guarantee time required when the system is operating and when the pump stage is increased. When the system is in operation, the set value of the pressure control system has a large difference from the measured value, so that it takes a long time to stabilize the control. For this reason, it is necessary to set the minimum flow rate guarantee time longer.

  On the other hand, since the difference is small when the pump is increased, the time until the control is stabilized can be shortened. As a result, when the pump stage is increased, the minimum flow rate guarantee time is set and waste occurs.

(3) In the secondary pump system, the pressure control system for the forward header discharge pressure by the pressure adjusting unit 19 and the pressure control system for the heat source discharge pressure by the heat source control device 40 are independent of each other. When the primary cold / warm water Fa of the heat source flowing from the primary forward header 31 in the direction of the return header 5 is equal to the secondary cold / warm water Fb flowing in the direction of the primary forward header 31 from the return header 5 to the bypass header 12, Get higher. However, it is difficult to realize this ideal state only with the pressure control system of the heat source discharge pressure by the heat source control device 40.

  An object of the present invention is to realize an air conditioning system capable of further enhancing the energy saving effect by the inverter control of the heat source pump than the conventional method.

In order to achieve such a subject, the present invention has the following configuration.
(1) Chilled / hot water heat-exchanged by a plurality of heat sources is sent to an air conditioner via a forward header by a plurality of heat source pumps whose rotation is controlled by an inverter frequency, and the chilled / hot water heat-exchanged by the air conditioner is In an air conditioning system that circulates to the heat source via a return header,
A pipe resistance pressure calculating means based on the measured value of the amount of reflux of the cold / hot water;
Minimum flow rate guarantee pressure calculating means based on the number of operating heat source pumps,
A high selector for inputting the calculated value of the pipe resistance pressure calculating means and the calculated value of the minimum flow rate guaranteed pressure calculating means;
A pressure controller that outputs the operation amount to the inverter by controlling and calculating a deviation from the pressure measurement value of the forward header, with the selection output of the high selector as a pressure set value,
Corresponding to the time of starting and increasing the stage of the heat source pump, the flow rate guarantee time calculating means for maintaining the operation amount to the inverter at a maximum value for a predetermined time;
Bypass valve opening degree calculation means for adjusting the flow rate of cold / hot water to be bypassed from the forward header to the return header during a period when the operating point of the heat source pump is at the minimum flow rate guarantee setting value higher than the pipeline resistance pressure calculation value When,
An air conditioning system comprising:

( 2 ) Cold / hot water heat-exchanged by a plurality of heat sources is sent to an air conditioner by a plurality of heat source pumps whose rotation is controlled at the frequency of the inverter, via a primary forward header and a secondary forward header having a secondary pump. In the air conditioning system for circulating the cold / hot water heat-exchanged by the air conditioner to the heat source via a return header,
A recirculation amount proportional calculation means for calculating an operation amount to the inverter in proportion to a recirculation amount value of the cold / hot water;
A minimum flow rate value calculating means for calculating a minimum flow rate value guarantee operation amount based on the number of operating heat source pumps;
A high selector that inputs a calculation value of the reflux amount proportional calculation means and a calculation value of the minimum flow rate value calculation means, and selectively outputs an operation amount to the inverter;
Corresponding to the time of starting and increasing the stage of the heat source pump, the flow rate guarantee time calculating means for maintaining the operation amount to the inverter at a maximum value for a predetermined time;
During the cooling operation, during the period when the temperature measurement value of the second forward header exceeds the set temperature upper limit value, the operation amount to the inverter is maintained at the maximum value, and the temperature measurement value of the second forward header is set during the heating operation. In the period when the temperature is lower than the lower temperature limit, cold / hot water temperature compensation means for maintaining the operation amount to the inverter at a minimum value;
An air conditioning system comprising:

According to the present invention, the following effects can be expected.
(1) When the flow rate demand from the air conditioner is small and the number of operating heat source pumps is small, the required minimum flow rate value is also lowered. Therefore, the energy saving effect is further improved by lowering the set pressure from the conventional pressure set value P1. Can be made.

  Since the shaft power of the pump is proportional to the cube of the flow rate, a large energy saving effect can be obtained with the pump power if a pressure set value that can individually obtain the minimum flow rate value is prepared according to the number of pumps operated.

(2) In the case of the direct feed system, a higher energy saving effect can be obtained by combining variable head control in accordance with the pipe resistance.

(3) By using two types of timers, the minimum flow rate guarantee time T2 for system startup and the minimum flow rate guarantee time T3 for pump step-up, the waste at the time of pump step-up is eliminated and a higher energy saving effect is achieved. Can be obtained.

(4) In the secondary pump system, the flow rate of the heat source is inverter-controlled based on the recirculation amount from the air conditioner, so that the primary cold temperature of the heat source flowing in the bypass pipe 12 from the primary forward header 31 toward the return header 5 is controlled. Energy saving with no circulation of unauthorized cold / hot water flowing through the bypass line 12 by operating the water Fa equal to the secondary cold / warm water Fb flowing from the return header 5 through the bypass line 12 toward the primary forward header 31 Driving is possible.

It is a functional block diagram which shows one Example of the air-conditioning system by the direct sending system to which this invention is applied. It is a functional block diagram which shows the detail of the heat-source control apparatus of FIG. FIG. 2 is a characteristic diagram for explaining the transition of the number of direct-feed-type heat source pumps and pressure control operating points in FIG. 1. It is a wave form diagram explaining the guarantee operation | movement of the control output with respect to the driving | running state change of a heat source pump of FIG. It is a functional block diagram which shows one Example of the air conditioning system by the secondary pump system to which this invention is applied. It is a functional block diagram which shows the detail of the heat-source control apparatus of FIG. It is a characteristic view explaining the operating point transition of the manipulated variable output based on the number of secondary heat source pump operation heat pumps and the recirculation amount of FIG. It is a wave form diagram explaining the guarantee operation | movement of the control output with respect to the going header temperature of FIG. It is a functional block diagram which shows the structural example of the conventional central air conditioning system by a direct sending system. It is a characteristic view explaining the transition of the heat source pump operation number and the pressure control operation point. It is a wave form diagram explaining the guarantee operation | movement of the control output with respect to the driving | running state change of a heat source pump. It is a functional block diagram which shows the structural example of the conventional central air conditioning system by a secondary pump system.

  Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a functional block diagram showing an embodiment of an air conditioning system using a direct delivery system to which the present invention is applied. The same elements as those in the conventional air-conditioning system according to the conventional direct delivery system described with reference to FIG.

  In FIG. 1, the basic configuration around the heat source and the air conditioner is the same as the configuration in FIG. The difference is that the opening degree of the bypass valve 13 is controlled by the operation amount MV3 on the heat source control device 100 side to which the present invention is applied.

  In the air conditioning system of the present invention, the number of heat sources and heat source pumps is not limited, but for simplicity of explanation, the heat source and the heat source pump are temporarily shown as two similarly to the conventional air conditioning system (FIG. 9). The air conditioning system of the present invention is based on the premise that the control of the number of heat sources and heat source pumps of the conventional air conditioning system is functioning.

  A functional configuration of the heat source control device 100 will be described. The pipe resistance pressure calculation means 101 inputs the measured value PV1 of the reflux sensor 10 and outputs a pressure set value Px. The minimum flow rate guaranteed pressure calculation means 102 inputs the operation state signals D1 and D2 of the heat source pumps 6 and 7 whose number of operation is managed by a host system (not shown), and outputs the minimum flow rate guaranteed pressure Pn.

  The high selector 103 receives the pressure set value Px and the minimum flow rate guarantee pressure Pn, selects a large value, and outputs the set value CAS. The pressure controller 104 controls and calculates the deviation between the measured value PV2 of the pressure sensor 11 in the forward header 3 and the set value CAS selected by the high selector 103, and outputs an operation amount MV.

  The flow rate guarantee time calculation means 105 receives the operation state signals D1 and D2 of the heat source pumps 6 and 7, and outputs an operation amount MV that identifies the time of start and the time of step increase. The high selector 106 inputs the operation amount MV of the pressure controller 104 and the operation amount MV of the flow rate guarantee time calculation means 105, and selects a large value.

  The manipulated variable MV selected by the high selector 106 is distributed to MV1 and MV2 by the MV value distribution means 107 and output to the inverters 8 and 9 that drive the heat source pumps 6 and 7. The bypass valve opening calculation means 108 inputs the operation amount MV selected by the high selector 106, outputs the operation amount MV3, and controls the opening of the bypass valve 13 inserted in the bypass pipe line 12.

  FIG. 2 is a functional block diagram showing details of the heat source control device 100 of FIG. The pipe resistance pressure calculation means 101 inputs the measured value PV1 of the reflux sensor 10, calculates a predetermined pipe resistance pressure curve R using the flow rate F as a parameter, and sets an optimum pressure setting value for the given flow rate F. Px is output. This pipeline resistance pressure calculation is a well-known technique and is disclosed in Patent Document 1.

  The minimum flow rate guarantee pressure calculation means 102 inputs the operation state signals D1 and D2 of the heat source pumps 6 and 7, and the minimum flow rate guarantee pressure P1 when operating one pump and the minimum flow rate guarantee pressure when operating one pump. P2 is output as the minimum flow rate guarantee pressure Pn. As described above, the point that the minimum flow rate guarantee pressure is changed according to the number of operating pumps is different from the conventional fixed pressure setting method.

  The flow rate guarantee time calculation means 105 inputs the operation state signals D1 and D2 of the heat source pumps 6 and 7, and outputs an operation amount MV. The system startup timer 105a set at the timer time T2 and the step-up timer 105b set at the timer time T3 are provided. The logic circuit for inputting D1 and D2 and the SR flip-flop, the manipulated variable at the time T2 at the system startup. When MV is increased, the manipulated variable MV at time T2 is output to the high selector 106.

  The bypass valve opening calculating means 108 inputs the operation amount MV selected by the high selector 106, and when the pump operating point is above the minimum flow rate guarantee pressure set value higher than the pipe line resistance pressure curve R, the heat source minimum An operation amount MV3 for bypassing the surplus flow rate for securing the flow rate between the return headers is output.

  FIG. 3 is a characteristic diagram for explaining the transition of the number of directly operated heat source pumps and the pressure control operating point in FIG. FIG. 3 (A) shows the relationship between the flow rate F and the number of operating heat source pumps, as in FIG. 10 (A). If the hysteresis is omitted, at the pump stepping point P, the single unit operation is switched to the two unit operation at the flow rate F1max or more, and the two unit operation is switched to the single unit operation at the flow rate F1max or less.

  FIG. 3B shows a pressure characteristic K1 of one pump with respect to a flow rate F, a pressure characteristic K2 of two pumps, a pipe resistance pressure curve R, a conventional minimum flow rate guarantee pressure setting value P1, and a minimum value employed in the present invention. The relationship between the flow rate guarantee pressure setting values P2 and P3 is shown.

  The maximum flow rate F2max of the two pump operation is determined by the intersection A of the pressure characteristic K2 and the pipe resistance pressure curve R of the two pump operation, and the pressure at this point A determines the minimum flow rate guarantee pressure setting value P1 of the conventional system. Yes.

  In the present invention, the minimum flow rate guarantee pressure setting value P2 lower than the minimum flow rate guarantee pressure setting value P1 of the conventional system is set when operating two units, and the minimum flow rate guarantee pressure setting value lower than P2 is set when operating one unit. By setting P3, further energy saving is realized.

  At the peak of air conditioning load such as midsummer daytime and severe winter season, the amount of heat consumed by the air conditioner increases, so the flow rate increases. When the flow rate is maximum, the operating point is point A. As the peak time passes and the heat load is reduced, the flow rate is also reduced. In the case of constant discharge pressure control by the conventional system, the operating point moves on a straight line from point A to point B as described with reference to FIG.

  In the discharge pressure variable control according to the present invention, the variable flow range control according to the pipe resistance curve R and the minimum flow rate guarantee control by the minimum flow rate guarantee pressure setting values P2 and P3 according to the number of operating heat source pumps are performed. The operating point moves.

  The intersection of the pipe resistance curve R and the set value P2 is the C point, the pipe resistance curve R at the flow rate F1max when switching the pump is the F point, the intersection of the pipe resistance curve R and the set value P3 is the G point, and the flow rate is zero The set value P3 is indicated by D point, and the minimum flow rate guarantee pressure set value P3 at F1max is indicated by H point.

  The operating point when the flow rate is reduced is A → C → E in the case of variable head control without considering the number of operating heat source pumps. However, according to the present invention, the operating point is considered by considering the operating number of heat source pumps. Changes from A → C → D → F → G → H, and it becomes possible to greatly reduce the set pressure at the time of low flow rate, and to reduce the power of the heat source pump.

  When the pump operating point is between C-D or GH, that is, when the pump operating point is on the minimum flow rate guarantee pressure set value higher than the pipe resistance pressure curve R, the bypass valve opening calculating means 108 Outputs an operation amount MV3 for performing bypass control between the return flow header and the surplus flow rate in order to ensure the minimum flow rate of the heat source to the bypass valve 13.

  FIG. 4 is a waveform diagram for explaining the control output guarantee operation for the operation state change of the heat source pump by the flow rate guarantee time calculation means 204. As in FIG. 11, FIG. 4A is the operating state of the heat source pump 6, (B) is the operating state of the heat source pump 7, and (C) is the operation amount MV1 of the inverter 8 that drives the heat source pump 6, (D). Indicates the waveform of the manipulated variable MV2 of the inverter 9 that drives the heat source pump 7.

  The system is activated at time t0, and the heat source pump 6 is changed from the stopped state to the operating state. During a period of time T2 from time t0 to time t1, the operation amount MV1 of the inverter 8 that drives the heat source pump 6 is forcibly maintained at 100%.

  When the pump stage is increased at time t2, the heat source pump 7 is changed from the stopped state to the operating state. The control output of the inverter 8 that drives the heat source pump 6 and the operation amount MV2 of the inverter 9 that drives the heat source pump 7 are forcibly maintained at 100% for a certain time T3 shorter than T2 from time t2 to time t3. To do.

  When the pump step-down occurs at time t4, the heat source pump 6 changes from the operating state to the stopped state. In this case, the forced change of the operation amount for the inverter 8 and the inverter 9 is not performed.

  In this way, by using two types of timers, the minimum flow rate guarantee time T2 for system start-up and the minimum flow rate guarantee time T3 for pump stage increase, it becomes possible to eliminate waste at the time of pump stage increase. Further energy saving effect can be obtained.

  FIG. 5 is a functional block diagram showing an embodiment of an air conditioning system using a secondary pump system to which the present invention is applied. Unlike the direct feed system, the secondary pump system does not perform pressure control by pipe resistance.

  In the direct delivery system, the heat source pump is subject to fluctuations in the air conditioning load, but in the secondary pump system, the secondary pump 17 is affected by the change in pipe resistance due to fluctuations in the heat source air conditioning load. This is because the change in road resistance is not affected.

  The configuration around the air conditioner is the same as the conventional configuration shown in FIG. The heat source control apparatus 200 to which the present invention is applied measures the reflux amount from the air conditioner 4 by the reflux amount sensor 10, and the heat source pump 6, so that the reflux amount becomes equal to the flow rate of the cold / hot water output from the heat source. The flow rate proportional control is executed by manipulating the frequencies of the inverters 8 and 9 that drive 7.

  If the recirculation amount from the air conditioner 4 and the flow rate of the cold / hot water from the heat sources 1 and 2 are equal, the flow rate flowing through the bypass pipe becomes Fa = Fb, and the waste of the cold / hot water flowing through the bypass pipe becomes zero. Energy saving of the pump can be achieved.

  The basic concept of the recirculation amount proportional control adopted in the present invention is that the recirculation amount sensor 10 takes in the instantaneous flow rate value PV1, and outputs an operation amount MV that gives the heat source pump rotation speed at which the flow rate is obtained to the inverter.

Since the flow rate is the number of revolutions (= inverter frequency), the manipulated variable MV is an inverter frequency proportional to the instantaneous flow rate value. For example, if instantaneous flow rate = 800m3 / h, rated heat source pump flow rate = 500m3 / h (50Hz), and 2 pumps
Inverter frequency = 800 / (500 * 2) = 0.8 = 80% = 50Hz * 0.8 = 40Hz
As a result, Fa = Fb is realized, and the flow rate flowing through the bypass conduit 12 becomes zero.

  Again, as a restriction, the minimum flow rate value of the heat source becomes a problem. Even if the flow rate is 0, if the inverter frequency is set to 0, the flow rate flowing to the heat source becomes 0. Therefore, the status signal of the heat source pump is taken in, the inverter frequency that gives the minimum flow rate value according to the number of operating heat source pumps is determined, and a high-selection of this value and the inverter frequency of the recirculation amount proportional control is set as the operation amount to the inverter. There is a need to.

  A functional configuration of the heat source control device 200 will be described. The recirculation amount proportional calculation means 201 inputs the measurement value PV1 of the recirculation amount sensor 10 and outputs an operation amount MV for recirculation amount proportional control. The minimum flow rate value guarantee pressure calculation means 202 inputs the operation state signals D1 and D2 of the heat source pumps 6 and 7 whose number of operation is managed by a host system (not shown), and obtains an operation amount MV for guaranteeing the minimum flow rate. Output.

  The flow rate guarantee time calculation means 203 has the same configuration as 105 in FIG. 1, inputs the operation state signals D1 and D2 of the heat source pumps 6 and 7, and outputs the manipulated variable MV that identifies the start time and the step-up time.

  In the secondary pump system, it may be necessary to keep the temperature of the cold / hot water constant from the necessary conditions such as the dew point temperature control of the air conditioner. In the heat source control device 200 to which the present invention is applied, the temperature measurement value PV3 of the secondary forward header 32 is taken in, and when the forward temperature is out of the set range, the operation amount of the heat source pump is adjusted to thereby control the forward temperature constant. I do.

  The cold / hot water temperature compensation means 204 receives the measured value PV3 of the temperature sensor 15 of the secondary header 32, and sets an operation amount MV that regulates the flow rate of the cold / hot water when the temperature rises or decreases beyond a predetermined alarm. Output.

  The high selector 205 inputs the operation amount MV output from the recirculation amount proportional calculation means 201, the minimum flow rate value guarantee pressure calculation means 202, the flow rate guarantee time calculation means 203, and the cold / hot water temperature compensation means 204, and selects a large value. To do.

  The manipulated variable MV selected by the high selector 205 is distributed to MV1 and MV2 by the MV value distribution means 206, and is output to the inverters 8 and 9 that drive the heat source pumps 6 and 7.

  FIG. 6 is a functional block diagram showing details of the heat source control device 200. The recirculation amount proportional calculation means 201 inputs the measurement value PV1 of the recirculation amount sensor 10, calculates the operation amount MV proportional to the flow rate F, and outputs it to the high selector 205. The proportionality factor is determined by the specifications of the pump and inverter.

  The minimum flow rate guaranteed pressure calculation means 202 inputs the operation state signals D1 and D2 of the heat source pumps 6 and 7, and when the single pump is operated, the minimum flow guaranteed operation amount MV1 is obtained, and when the two pumps are operated, the minimum flow rate is obtained. The guaranteed operation amount MV2 is output to the high selector 205 as the minimum flow rate guaranteed operation amount MV.

  The flow rate guarantee time calculation means 203 inputs the operation state signals D1 and D2 of the heat source pumps 6 and 7, and outputs an operation amount MV. The system startup timer 203a set at the timer time T2 and the step-up timer 203b set at the timer time T3 are provided. The logic circuit for inputting D1 and D2 and the SR flip-flop, the manipulated variable at the time T2 at the system startup. When MV is increased, the manipulated variable MV at time T2 is output to the high selector 205.

  The cold / hot water supply temperature compensation means 204 inputs the measured value PV3 of the temperature sensor 15 of the secondary going header 32, and when the air conditioning side load increases during cooling and the going temperature rises and exceeds the set temperature upper limit (high alarm) Further, the compensation control of the forward temperature is performed by securing the amount of heat to the air conditioner side with the operation amount MV of the heat source pump as 100%.

  If the load on the air-conditioning side increases during heating and the forward temperature falls and exceeds the set temperature lower limit (low alarm), the heat source pump operation amount MV is set to 0% to secure the amount of heat to the air-conditioner side. Compensation control is performed.

  FIG. 7 is a characteristic diagram for explaining the operating point transition of the manipulated variable output based on the number of secondary-pump heat source pumps operated and the recirculation amount. FIG. 7 (A) shows the relationship between the flow rate F and the number of operating heat source pumps, as in FIG. 10 (A). If the hysteresis is omitted, at the pump stepping point P, the single unit operation is switched to the two unit operation at the flow rate F1max or more, and the two unit operation is switched to the single unit operation at the flow rate F1max or less. FIG. 7B shows the operating point transition of the manipulated variable output based on the number of operating units and the reflux amount.

  Although the minimum flow rate value of the heat source varies widely depending on the manufacturer and specifications, it is generally about 50% of the rated flow rate (= pump rated flow rate) of the heat source. However, the accuracy of the flow sensor attached to the heat source is not high, and if the flow rate is reduced to 50%, the protection circuit may work and the heat source may stop urgently, so there is a margin of about + 15%. This is the minimum flow rate value for control. Therefore, in FIG. 7B, the minimum flow rate value is expressed as 65%.

(1) When the number of operating units is one:
The value of the reflux amount F is displayed on the X1 axis. The manipulated variable MV from the reflux amount proportional calculation means 201 changes from 0% to 100% according to the straight line G1 with respect to the flow rate change of 0% to 100%. In the region where the flow rate is 65% to 100%, the operation amount MV also increases proportionally from 65% to 100% according to G1.

  In the region where the flow rate is 65% or less, the manipulated variable MV is regulated to a constant value of 65% in order to ensure the minimum flow rate without following G1. Therefore, the operating point transitions to ABC.

(2) When the number of operating units is two:
The value of the reflux amount F is displayed on the X2 axis. The manipulated variable MV from the reflux amount proportional calculation means 201 changes from 0% to 100% in accordance with the straight line G2 with respect to the change in flow rate from 0% to 100%. In the region where the flow rate is 65% to 100%, the manipulated variable MV increases proportionally from 65% to 100% according to G2.

  In the region where the flow rate is 65% or less, the manipulated variable MV is regulated to a constant value of 65% in order to ensure the minimum flow rate without following G2. Therefore, the operating point transitions to D-E-F.

  FIG. 8 is a waveform diagram for explaining the control output guarantee operation with respect to the forward header temperature. FIG. 8A shows a change in the temperature measurement value PV3 of the secondary header 32, and exceeds the set temperature upper limit SVH during the period from time t1 to time t2.

  FIG. 8B shows the transition of the inverter operation amounts MV1 and MV2 of the heat source pump during cooling. During the period from time t1 to time t2 when the temperature measurement value PV3 exceeds the set temperature upper limit value SVH, the operation amounts MV1 and MV2 are forcibly restricted to 100%.

  When the temperature measurement value PV2 falls below the set temperature lower limit value SVL during cooling, it is not shown in the figure, but during the period when PV3 falls below the set temperature lower limit value SVL, the manipulated variables MV1 and MV2 are forced to 0%. Be regulated.

  The configuration of the flow rate guarantee time calculation means 203 is the same as that of the flow rate guarantee time calculation means 105 in the direct delivery system of FIG. Therefore, the operation characteristics are the same as those described with reference to FIG.

  In the air conditioning system of the embodiment described above, the case where there are two heat sources is shown for the sake of simplicity. However, the present invention can be applied to an air conditioning system including three or more heat sources. A big energy saving effect can be expected.

1, 2 Heat source 3 Out header 4 Air conditioner 5 Return header 6, 7 Heat source pump 8, 9 Inverter 10 Reflux sensor 11 Pressure sensor 12 Bypass pipe 13 Bypass valve 100 Heat source controller 101 Pipe resistance pressure calculation means 102 Minimum flow rate Value guaranteed pressure calculation means 103 High selector 104 Pressure controller 105 Flow rate guarantee time calculation means 106 High selector 107 MV value distribution means 108 Bypass valve opening calculation means

Claims (2)

Chilled / hot water heat-exchanged by a plurality of heat sources is sent to the air conditioner via a forward header by a plurality of heat source pumps controlled to rotate at the inverter frequency, and the chilled / hot water heat-exchanged by the air conditioner is returned to the header. In an air conditioning system that circulates to the heat source via
A pipe resistance pressure calculating means based on the measured value of the amount of reflux of the cold / hot water;
Minimum flow rate guarantee pressure calculating means based on the number of operating heat source pumps,
A high selector for inputting the calculated value of the pipe resistance pressure calculating means and the calculated value of the minimum flow rate guaranteed pressure calculating means;
A pressure controller that outputs the operation amount to the inverter by controlling and calculating a deviation from the pressure measurement value of the forward header, with the selection output of the high selector as a pressure set value,
Corresponding to the time of starting and increasing the stage of the heat source pump, the flow rate guarantee time calculating means for maintaining the operation amount to the inverter at a maximum value for a predetermined time;
Bypass valve opening degree calculation means for adjusting the flow rate of cold / hot water to be bypassed from the forward header to the return header during a period when the operating point of the heat source pump is at the minimum flow rate guarantee setting value higher than the pipeline resistance pressure calculation value When,
An air conditioning system comprising: Chilled / hot water heat-exchanged by a plurality of heat sources is sent to the air conditioner by a plurality of heat source pumps that are rotationally controlled at the frequency of the inverter, via a secondary forward header and a secondary forward header including a secondary pump. In the air conditioning system for circulating the cold / hot water heat-exchanged in the heat source through a return header,
A recirculation amount proportional calculation means for calculating an operation amount to the inverter in proportion to a recirculation amount value of the cold / hot water;
A minimum flow rate value calculating means for calculating a minimum flow rate value guarantee operation amount based on the number of operating heat source pumps;
A high selector that inputs a calculation value of the reflux amount proportional calculation means and a calculation value of the minimum flow rate value calculation means, and selectively outputs an operation amount to the inverter;
Corresponding to the time of starting and increasing the stage of the heat source pump, the flow rate guarantee time calculating means for maintaining the operation amount to the inverter at a maximum value for a predetermined time;
During the cooling operation, during the period when the temperature measurement value of the second forward header exceeds the set temperature upper limit value, the operation amount to the inverter is maintained at the maximum value, and the temperature measurement value of the second forward header is set during the heating operation. In the period when the temperature is lower than the lower temperature limit, cold / hot water temperature compensation means for maintaining the operation amount to the inverter at a minimum value;
An air conditioning system comprising:

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