JP2006275397A - Cold/hot water control method for air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cold/hot water control method for an air conditioning system using a local cold/hot water pump in each of air conditioners and to be operated with the maximum energy efficiency over the whole of the system in consideration of power consumption over the whole of the air conditioning system. <P>SOLUTION: In the cold/hot water control method for the air conditioning system provided with a plurality of secondary equipment 1 and a plurality of secondary cold/hot water local pumps 16, a cold/hot heat source machine 8, a primary cold/hot water pump 18, and a bypass pipe 17 provided between a cold/hot water supply pipe 3a and a cold/hot water circulation pipe 3b, power consumption of each of the local pumps 16, the cold/hot heat source machine 8 and the primary cold/hot water pump 18 are added to compute system power consumption. Total flow of the secondary equipment 1 side cold/hot water is obtained through the bypass pipe 17 and secondary calorie is computed on the basis of a temperature difference between the cold/hot water supply pipe 3a and the cold/hot water circulation pipe 3b, and system COP is computed by dividing the secondary calorie by the system power consumption, and outlet temperature of the cold/hot heat source machine 8 is set to obtain the maximum system COP. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a cold / hot water control method for an air conditioning system.

  2. Description of the Related Art Conventionally, an air conditioning system that air-conditions a plurality of air-conditioning areas by supplying cold / hot water (cold water or hot water) from a cold / heat source to a plurality of air conditioners has been used. Such an air conditioning system is disclosed in Non-Patent Document 1. In addition, a cold / hot heat source machine means the refrigerator which produces | generates cold water, the heat pump type heat source machine which produces | generates cold water and warm water, the boiler which produces | generates warm water, etc.

FIG. 8 is a block diagram of a conventional air conditioning system.
Each of the plurality of air conditioners 1 includes a cold / hot water coil. Cold / hot water is supplied to the cold / hot water coil of each air conditioner 1 through the cold / hot water pipe 3. The chilled / hot water pipe 3 includes a chilled / hot water supply pipe 3 a that feeds chilled / warm water to each air conditioner 1, and a chilled / hot water return pipe 3 b that returns the chilled / warm water that has passed through each air conditioner 1. The cold / hot water supply pipe 3a of the cold / hot water pipe 3 of each air conditioner 1 is provided with a control valve 4 for adjusting the flow rate of the cold / hot water for each air conditioner.

  Each air conditioner 1 is installed, for example, for each floor of a building, and an air supply duct for each air conditioning system is connected thereto. Each air conditioner 1 includes an air supply fan, and sends air conditioned through an air supply duct to an air conditioning area of each air conditioning system.

  The cold / hot water is generated by the cold / hot heat source unit 8. The cold / hot water is sent from the cold / hot heat source unit 8 to the primary header 10 by the primary cold / warm water pump 9, and is supplied from there to the air conditioners 1 via the secondary header 12 by the secondary cold / hot water pump 11.

  FIG. 9 is a pressure diagram of the air conditioning system of FIG. In the figure, (a) to (g) indicate pressures at the positions of the same letters (a) to (g) in FIG. a and b show the pressure loss by an air conditioner and a control valve in each floor.

  In the conventional air conditioning system, since the cold / hot water is circulated to the top floor by the common secondary cold / hot water pump 11 for the air conditioners on each floor, the secondary cold / hot water pump 11 secures the pump head to the top floor, A water supply pressure is needed to cover the pressure loss b of the control valve as well as the pressure loss a of the air conditioner on the floor. In this case, it is necessary to throttle the control valve on each floor in order to supply cold / hot water to the floor above it. Therefore, the pressure loss of the control valve on each floor is wasted in terms of energy, and wasteful power consumption that does not contribute to the operation of the system is generated. As for the pump head, because of the pipe resistance in the height direction, the difference between the pipe pressure on the forward side and the pipe pressure on the return side widens to the lower floors, and eventually the pressure in the height pipe along with the throttle pressure loss due to the control valve. A large secondary cold / hot water pump with high power consumption that can cover the loss is required.

  In this case, instead of the control valve, a local cold / hot water pump (hereinafter referred to as a local pump) is provided for each air conditioner, and a necessary amount of cold / hot water is supplied to each air conditioner by inverter control of each local pump. It is conceivable to eliminate useless power consumption by the control valve. However, this alone does not aim for the maximum energy efficiency of the total system including the cold / hot heat source machine, because each local pump operates as required.

“Energy Saving” Vol. 55, No. 3, pages 105-112 Published February 28, 2003 by the Energy Saving Center

  The present invention takes the above-mentioned prior art into consideration, and uses a local pump for each air conditioner instead of the flow control of cold / hot water using a control valve for each air conditioner, and considers the power consumption of the entire air conditioning system. The purpose is to provide a cold / hot water control method for an air conditioning system that can be operated with maximum energy efficiency as a whole system.

  In order to achieve the above object, the invention of claim 1 includes a plurality of secondary equipment, a local pump for supplying secondary cold / hot water provided in each secondary equipment, and a cold / hot heat source for producing cold / hot water. A primary cold / hot water pump for supplying cold / hot water generated by the cold / hot heat source machine to the local pump, and a cold / hot water supply pipe for supplying cold / hot water from the outlet side of the cold / heat source machine to the secondary equipment An air conditioning system comprising: a cold / hot water return pipe for returning cold / hot water returning from the secondary equipment to the inlet side of the cold / hot heat source machine; and a bypass pipe provided between the cold / hot water supply pipe and the cold / hot water return pipe In the cold / hot water control method, the system power consumption is calculated by summing the power consumption of the local pump, the power consumption of the cold / hot heat source unit, and the power consumption of the primary cold / hot water pump, Total water flow and cold / hot water supply pipe The secondary heat quantity is calculated from the temperature difference of the cold / hot water temperature of the cold / hot water return pipe, the system COP is calculated from the secondary heat quantity / the system power consumption, and the cold / heat source so that the system COP is maximized. A cold / hot water control method for an air conditioning system, characterized in that an outlet temperature of a machine is set.

  According to a second aspect of the present invention, in the first aspect of the invention, each of the primary cold / hot water pump and the local pump includes an inverter for controlling the number of rotations, and the total flow of cold / hot water on the secondary side equipment side is the cold / hot water. The flow rate of the primary cold / hot water pump is controlled by an inverter so as to be equal to the flow rate of the cold / hot water generated through the heat source unit.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the set temperature of the cold / hot heat source unit is changed in a rising or falling direction by a predetermined temperature difference at a predetermined cycle, and the system COP is calculated to calculate the previous time. Compared with the calculated system COP, if it increases, the set temperature is changed in the same direction by the predetermined temperature difference, and if it decreases, the set temperature is changed in the reverse direction by the predetermined temperature difference. Features.
According to a fourth aspect of the present invention, in the second or third aspect of the invention, when the inverter output of any of the local pumps is close to the maximum output of the pump (for example, 95% or more), the outlet setting of the cold / hot heat source machine is set. The temperature is lowered in the case of cold water and raised in the case of hot water.

  According to the first aspect of the present invention, a local pump is provided for each of the secondary-side equipment such as a plurality of air conditioners in place of the conventional control valve to reduce wasteful power consumption due to the restriction of the control valve. In addition, the power consumption of the entire system including the power consumption of the cold / hot heat source machine and the primary cold / hot water pump is calculated, and the system COP is obtained from the secondary heat quantity consumed by the secondary equipment with respect to the whole system power consumption. Since the set temperature of the cold / hot heat source machine is controlled so that the COP is maximized, the maximum energy saving effect can be obtained as a whole system.

  According to the invention of claim 2, the primary chilled hot water pump and the local pump are controlled in rotation speed by the inverter, and a necessary flow rate can be obtained without causing a wasteful pressure loss due to a valve throttle or the like. can get. Also, by making the flow of cold / hot water on the secondary equipment side equal to the flow of cold / hot water flowing through the cold / hot heat source machine, the cold temperature of the inlet and outlet of the cold / hot heat source machine that supplies cold / hot water from the cold / hot heat source machine to the secondary equipment There is no need to provide a header in the water pipe. This simplifies the piping configuration, eliminates pressure loss due to the header, and further enhances the energy saving effect.

  According to the invention of claim 3, the set temperature of the cold / hot heat source machine is adjusted following the change in the ambient temperature and the fluctuation of the heat load, and the entire system can always be operated at maximum efficiency in real time.

  According to the invention of claim 4, when the local pump is operated near the maximum output (for example, 95% or more) and the flow rate of the cold / hot water cannot be increased further, the secondary side equipment is further subjected to a heat load. When the amount of heat to be dealt with is required, the heat load of the secondary equipment can be dealt with without increasing the flow rate of cold / hot water.

FIG. 1 is an overall configuration diagram of an air conditioning system according to the present invention. As the air conditioner used in the air conditioning system according to the present invention, various types of air conditioners can be used as long as they have a cold / hot water coil. For example, it is also used for a non-duct system such as a variable air volume system, a constant air volume system, or a fan coil system.
The air conditioner 1 is installed on each floor of a building, for example. Each air conditioner 1 is connected to a supply duct for each air conditioning area.

  Each air conditioner 1 includes a cold / hot water coil. A chilled / hot water supply pipe 3a which is a forward side of the chilled / hot water pipe 3 is connected to each chilled / hot water coil. A local pump 16 is provided in the cold / hot water supply pipe 3 a connected to each air conditioner 1. Thus, each local pump 16 provided locally for each air conditioner includes an inverter 16a for controlling the rotational speed, and the flow rate is controlled by the inverter.

  The outlet side and the inlet side of the cold / hot heat source unit 8 that generates the cold / hot water are connected to the root part (lowermost layer part) of the outgoing cold / hot water supply pipe 3a and the root part of the cold / hot water return pipe 3b. The cold / hot water supply pipe 3 a and the cold / hot water return pipe 3 b at the base part are communicated with each other by a bypass pipe 17. The cold / hot water generated by the cold / hot heat source unit 8 is sent to the cold / hot water supply pipe 3 a by the primary cold / hot water pump 18. The primary cold / hot water pump 18 includes an inverter 18a, and the flow rate is controlled by rotational speed control by the inverter.

  FIG. 2 is a pressure diagram of the air conditioning system of FIG. In the figure, (A) to (G) indicate pressures at the positions of the same letters (A) to (G) in FIG. a shows the pressure loss by the air conditioner in each floor.

  As can be seen from the figure, the air conditioning system of the present invention includes a local pump 16 (FIG. 1) for each air conditioner on each floor, and each pressure loss due to the air conditioner is covered by the water supply pressure (lift) of the local pump. By doing so, it is possible to omit the control valves that have been provided individually and eliminate unnecessary pressure loss due to the restriction of the control valves, thereby efficiently achieving energy saving.

FIG. 3 is a configuration diagram of a cold / hot water control system of the air conditioning system according to the present invention.
Each air conditioner 1 which is a secondary side equipment is provided with a local pump 16 and an inverter 16a for controlling the rotation speed thereof, and a wattmeter 21 is provided. A flow meter 22 for measuring the total amount of cold / hot water of all air conditioners is provided at the root of the cold / hot water return pipe 3b. Thermometers 25 and 26 are provided at the bases of the cold / hot water supply pipe 3a and the cold / hot water return pipe 3b, respectively.

  The primary cold / hot water pump 18 provided in the cold / hot water piping 32 of the cold / hot heat source machine 8 side from the bypass pipe 17 is provided with the wattmeter 23 with the inverter 18a. The cold / hot water pipe 32 is provided with a flow meter 24 for measuring the flow rate of the cold / hot water circulating through the cold / hot heat source unit 8. The cold / hot heat source device 8 includes a temperature setting device 30 and a wattmeter 31 for setting the temperature (outlet side temperature) of the produced cold / hot water.

  The wattmeter 21 of the local pump 16, the wattmeter 23 of the primary cold / hot water pump 18, and the wattmeter 31 of the cold / hot heat source machine 8 are connected to the system power consumption calculation device 28. The flow meter 22 and the thermometers 25, 26 of the secondary side cold / hot water pipe 3 are connected to the secondary side calorific value calculation device 27. The secondary heat amount calculation circuit 27 and the system power consumption calculation circuit 28 are connected to the controller 29. The controller 29 is connected to the inverter 18 a of the primary cold / hot water pump 18 and the temperature setting device 30 of the cold / hot heat source unit 8.

Next, the cold / hot water control method by the cold / hot water control system of the said structure is demonstrated.
The secondary-side calorific value calculation device 27 calculates the temperature difference (T2−T1) [° C.] between the cold / hot water temperatures T1 and T2 of the secondary cold / hot water supply pipe 3a and the return pipe 3b detected by the thermometers 25 and 26. The secondary-side heat quantity Q [kW] is calculated from the secondary-side cold / hot water flow rate F [L / h] detected by the flow meter 22.
Q = F · (T2-T1) / 860

The system power consumption calculation device 28 includes the total power of the wattmeter 21 of the local pump 16 provided for each air conditioner, the power of the wattmeter 23 of the primary cold / hot water pump 18, and the power of the wattmeter 31 of the cold / heat source device 8. To calculate the system power consumption Q0 [kW].
The controller 29 calculates the system COP = Q ÷ Q0 from the system power consumption Q0 and the secondary heat quantity Q.
Is calculated. The controller 29 changes the set temperature (outlet temperature) of the cold / hot heat source unit 8 so that the system COP is maximized. Thus, each local pump 16 can efficiently handle the heat load of the secondary equipment on each floor according to the cold / hot water temperature without causing unnecessary throttle loss of the control valve, and also considers the power of the entire system. The maximum energy saving effect can be obtained as a whole system.

  When the inverter output of any of the local pumps is, for example, 95% or more, the outlet set temperature is lowered (in the case of hot water, it is raised). That is, when one of the local pumps is operated at a substantially maximum flow rate (95% or more), the heat load of the secondary side equipment (air conditioner) of the system is large, and this heat load is dealt with. It is a situation that further requires cold water (in the case of cooling). However, since the local pump cannot increase the amount of chilled water any more, the chilled water set temperature of the heat source unit is lowered to cope with the heat load. In the case of heating, the reverse is true, instead of increasing the hot water flow rate, the set temperature of the hot water in the heat source machine is raised to deal with the heat load.

  Furthermore, the controller 29 controls the inverter 18a of the primary cold / hot water pump 18 so that the flow rate of the flow meter 22 of the cold / hot water return pipe 3b becomes equal to the flow rate of the flow meter 24 of the primary cold / hot water pipe 32. As a result, the flow rate of the cold / hot water whose temperature is controlled through the cold / hot heat source unit 8 becomes equal to the flow rate of the cold / hot water circulating through the secondary-side equipment, so that the capacity of the cold / hot heat source unit 8 is maximized and energy efficiency is increased. The headers on the inlet side and the outlet side of the machine 8 are not required, and the piping configuration is simplified and the pressure loss is reduced. However, the minimum flow rate of the heat source unit 8 is secured by the primary cold / hot water pump 18. In this case, when the minimum flow rate is larger than the flow rate of the return pipe 3b, cold / hot water flows through the bypass pipe 17.

FIG. 4 is a graph showing power consumption of the cold / hot heat source machine and the cold / hot water pump in the air conditioning system of the present invention.
As shown in the figure, when the cold water (hot water) temperature is higher (lower), the power consumption of the cold / hot heat source device (refrigerator in the case of cold water) is reduced. In this case, since a large amount of cold water (hot water) is required, the power consumption of the cold / hot water pump increases. Thus, although the power consumption of the cold / hot heat source machine and the cold / hot water pump is in a trade-off relationship, in the present invention, the cold / hot heat source machine and the cold / hot water pump are operated with maximum energy efficiency in consideration of the power consumption of the entire system. be able to.

FIG. 5 is a graph showing power consumption of the cold / hot water pump and the entire system.
As described above, when the temperature of the cold water (hot water) becomes higher (lower), the power consumption of the cold / hot heat source machine decreases as shown in the graph a. On the other hand, in this case, since the power consumption of the primary cold / hot water pump and the local pump requires a large amount of cold water (hot water), the power consumption increases as shown by the graphs b and c. The sum of the power consumption of these cold / hot heat source machines (graph a) and the power consumption of the primary cold / hot water pump and the local pump (graphs b and c) is the total power consumption shown in graph d. As can be seen from the figure, the power consumption (graph d) of the entire system becomes a minimum value at the temperature T0. The set temperature of the cold / hot heat source unit 8 (FIG. 3) is controlled so as to be the minimum cold / hot water temperature T0. That is, the total power consumption of the system is minimized by setting the set temperature of the cold / hot heat source machine to T0.

FIG. 6 is an explanatory diagram showing a method of determining the cold / hot water set temperature based on the system COP.
The controller sets the cold / hot water outlet temperature at a fixed period F (for example, 10 minutes), calculates the system COP, and determines the next set value depending on whether the system COP is higher or lower than the system COP of the previous set value. To do.

Further explaining with the example in the figure, the system COPs at times a0, a1, and a2 are COP0, COP1, and COP2, respectively, and the set temperatures are T0, T1, and T2. At time a0, the set temperature is raised (decreased) by a certain amount ΔT. If COP1 at time a1 after a certain period F is larger than the previous COP0, the COP increases, so the set temperature is also increased (decreased) by ΔT this time (state shown). On the contrary, if COP1 at this time (time a1) is smaller than COP0 of the previous time, since the COP is decreasing, the set temperature is decreased (increased) by ΔT, contrary to the previous time. Similarly, COP2 is calculated at time a2, and the set temperature is changed depending on whether it is rising or falling compared to the previous COP1. That is,
If COP1 ≦ COP2 and T1> T0, then T2 = T1 + ΔT (1)
If COP1 ≦ COP2 and T1 <T0, then T2 = T1−ΔT (2)
If COP1> COP2 and T1> T0, then T2 = T1-ΔT (3)
If COP1> COP2 and T1 <T0, then T2 = T1 + ΔT (4)
And set. In the case of warm water, + and-in each formula are reversed.

  By performing cascade control of the chilled / hot water outlet temperature based on the COP as described above, the optimum water temperature is determined while repeatedly raising and lowering the chilled / warm water temperature, as shown in part A. Further, when there is a load change, as shown in part B, the optimum set temperature is determined following the load change.

  FIG. 7 is a flowchart of a method for comparing COPs at times a1 and a2 in FIG. 6, and shows the same contents as the above-described equations (1) to (4) in a flow.

  INDUSTRIAL APPLICABILITY The present invention can be used for any air conditioning system including a heat pump type refrigerator, a refrigerator with only a refrigeration cycle, and a cooling / heating source including a boiler, and can effectively achieve energy saving by maximizing the operation efficiency of the entire system.

The block diagram of the air-conditioning system which concerns on this invention. The pressure line figure of the air conditioning system of FIG. The block diagram of the cold / hot water control system of the air conditioning system of FIG. Explanatory drawing of the power consumption of the cold / hot heat source machine and cold / hot water pump of the air-conditioning system of this invention. Explanatory drawing of the total power consumption of this invention. Explanatory drawing which shows the method of determining cold / hot water preset temperature based on the system COP of this invention. 7 is a flowchart of a method for comparing COPs at times a1 and a2 in FIG. The block diagram of the conventional air conditioning system. The pressure diagram of the conventional air conditioning system.

Explanation of symbols

1: air conditioner, 3: cold / hot water pipe, 3a: cold / hot water supply pipe, 3b: cold / hot water return pipe, 4: control valve, 8: cold / hot heat source machine, 9: primary cold / hot water pump, 10: primary header, 11: Secondary cold / hot water pump, 12: secondary header, 16: local pump, 16a: inverter, 17: bypass pipe, 18: primary cold / hot water pump, 18a: inverter, 21: power meter, 22: flow meter, 23: power 24: flow meter, 25: thermometer, 26: thermometer, 27: secondary calorie calculating device, 28: system power consumption calculating device, 29: controller, 30: temperature setting device, 31: watt meter, 32 : Cold / hot water piping.

Claims (4)

A plurality of secondary equipment,
A local pump for supplying secondary cold / warm water to each secondary facility,
A cold / hot heat source machine for producing cold / hot water,
A primary cold / hot water pump for supplying cold / hot water generated by the cold / hot heat source machine to the local pump;
A cold / hot water supply pipe for supplying cold / hot water from the outlet side of the cold / hot heat source machine to the secondary side equipment;
A cold / hot water return pipe for returning the cold / hot water returning from the secondary side equipment to the inlet side of the cold / hot heat source machine,
In the cold / hot water control method for an air conditioning system comprising a bypass pipe provided between the cold / hot water supply pipe and the cold / hot water return pipe,
Calculate the system power consumption by summing the power consumption of the local pump, the power consumption of the cold / hot heat source machine, and the power consumption of the primary cold / hot water pump,
Calculate the secondary heat quantity from the total cold water flow rate on the secondary equipment side and the temperature difference between the cold and hot water supply pipe and the cold and hot water temperature of the cold and hot water return pipe,
Calculate the system COP from the secondary heat quantity divided by the system power consumption,
A cold / hot water control method for an air conditioning system, wherein an outlet temperature of the cold / hot heat source machine is set so that the system COP is maximized.   Each of the primary cold / hot water pump and the local pump includes an inverter for controlling the number of revolutions so that the total cold / warm water flow rate on the secondary equipment side is equal to the cold / warm water flow rate generated through the cold / hot heat source machine. The cold / hot water control method for an air conditioning system according to claim 1, wherein the flow rate of the primary cold / hot water pump is controlled by an inverter.   When the set temperature of the cooling / heating heat source device is changed in the upward or downward direction by a predetermined temperature difference at a predetermined cycle, the system COP is calculated and compared with the previously calculated system COP. The set temperature is changed in the same direction by the difference in temperature, and when the temperature is decreased, the set temperature is changed in the opposite direction by the predetermined temperature difference. Control method. When the inverter output of any of the local pumps is close to the maximum output of the pump, the outlet set temperature of the cold / hot heat source machine is lowered in the case of cold water and raised in the case of hot water. Item 4. A method for controlling hot and cold water in an air conditioning system according to Item 2 or 3.

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