JP3175042B2 - Temperature control method of cold / hot water generator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling the temperature of a chilled / hot water generator in a system in which a plurality of chilled / hot water generators are connected in parallel to collect cold / hot water in a header section and then supply the same to a load side. The present invention relates to a temperature control method suitable for stabilizing cold and hot water mixed in a section at a predetermined temperature.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 6, a plurality of absorption-type cold / hot water generators are connected in parallel to the same system, and each of them performs proportional combustion control (determines a combustion amount corresponding to a set temperature). In the mounted system, the temperature control of each chilled / hot water generator is controlled based only on the chilled / hot water outlet temperature of each unit. That is, as shown in FIG. 7, each chilled / hot water generator sets a proportional band of the combustion amount in which the combustion amount is increased / decreased in response to an increase / decrease in the detected value of the chilled / hot water outlet temperature in a range around the set value of the chilled / hot water outlet temperature. Independently controlled by PID control or the like according to the curve. In this case, the cold / hot water temperature at the header section where the cold / hot water from each machine is mixed is the average temperature of the cold / hot water discharged from each machine, but the outlet temperatures from all the cold / hot water generators are set to be the same. If so, the mixed cold / hot water outlet temperature will also show the same value. In such conventional control, for example, the machines 1A, 1B, 1
Three units C are connected in parallel by the pipe 2 and one unit of the chilled / hot water generator breaks down or its capacity decreases during the cooling operation with the set temperature of all units set to 8 ° C., and the rated output cannot be obtained. .
If the cold / hot water outlet temperature of the faulty machine or the defective machine whose capacity has been reduced only drops to 10 ° C., the temperature of the cold / hot water at the header section 3 becomes (8 + 8 + 10) ÷ 3 = 8.7 (° C.). As a result, the temperature had to be different from 8 ° C. when all the machines were operating normally.

[0003]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problem, and an object of the present invention is to connect a plurality of cold / hot water generators in parallel, and to use a header section for combining cold / hot water from each machine into one. In a system that supplies cold and hot water to a load, the temperature of the cold and hot water at the header can be stabilized by controlling the target set temperature of each cold and hot water generator based on the mixed temperature of the cold and hot water at the header. An object of the present invention is to provide a temperature control method for a cold / hot water generator.

[0004]

In order to achieve the above object, a temperature control method for a chilled / hot water generator according to the present invention comprises a plurality of units.
In the temperature control method of the chilled / hot water generator in the system in which the chilled / hot water generators of (n) are connected in parallel, the chilled / hot water is collected from each machine in the header section and supplied at the header section set temperature (Ts), The temperature (Tn) and flow rate (Qn) of the cold and hot water generated from each machine by the temperature control device provided for each person
And the header part temperature Th is obtained as Th = ΣTi × Qi / ΣQi (where i: 1 to n), and the system operates in cooling operation or heating operation.
PID control to set its own cold / hot water outlet temperature set value Tc to a value apart from Ts in proportion to the magnitude of the temperature difference between h and Ts, and to increase the cooling or heating capacity of the cold / hot water generator. It is characterized by.

In the present invention, when the cooling / heating water generator is of an absorption type and the system is operated for cooling, when the header section temperature Th> Ts, the temperature of the cooling / heating water outlet is increased in proportion to the magnitude of the temperature difference. Is set lower than Ts, and as the Tc is lower and the actual temperature of the cold / hot water outlet is higher, the amount of combustion is increased to increase the cooling capacity by increasing the combustion in the cold / hot water generator.
Perform ID control. The relationship between the temperature difference (Th-Ts) and the cold / hot water outlet temperature set value Tc, and the cold / hot water outlet temperature set value Tc
It is preferable to obtain the relationship between and combustion in advance.

In the present invention, when the cold / hot water generator is an absorption type and the system is operated for heating, Ts> T
h, the set value Tc of its own cold / hot water outlet temperature is raised from Ts in proportion to the magnitude of this temperature difference (Ts-Th),
PID control of the combustion in the cold / hot water generator is performed so that the higher the value of c and the lower the actual temperature of the cold / hot water outlet, the greater the amount of combustion to increase the heating capacity. The relationship between the temperature difference (Ts-Th) and the chilled / hot water outlet temperature set value Tc, and the relationship between the chilled / hot water outlet temperature set value Tc and the combustion amount are preferably obtained in advance.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration of a chilled / hot water supply system according to an embodiment to which a chilled / hot water generator control method of the present invention is applied. Here, the present invention will be described by a simple system in which, for example, three absorption chilled / hot water generators are operated in parallel. Each of the cold / hot water generators 1A, 1B, and 1C has a proportional combustion device, a temperature control device, and a communication function, and is independently temperature-controlled. These cold and hot water generators 1
A, 1B, 1C are connected in parallel by a cold / hot water pipe 2,
Furthermore, temperature control devices 4A, 4B, 4C provided in each machine
Are connected by a communication line 6, and information such as a cold / hot water outlet temperature and a flow rate of each machine is transmitted to each other for the purpose of finding a cold / hot water mixing temperature in the header section.

FIG. 2 is a diagram showing a configuration of a temperature control device provided in the absorption type cold / hot water generator. Temperature control devices 4A, 4
B and 4C denote a cold / hot water temperature detection circuit 10, a temperature detection circuit 11, a combustion control circuit 12, and a peripheral input / output circuit 1, respectively.
3, a central processing unit 14, a communication circuit 15, and the like. The cold / hot water detection circuit 10 inputs the cold / hot water outlet temperature through the cold / hot water temperature detector 17, and the temperature detection circuit 11 of each section detects the refrigerant temperature and the outside air temperature during the refrigeration cycle. The combustion control circuit 12 controls combustion for generating refrigerant vapor, air blowing for condensing refrigerant vapor, and the like according to the set temperature of the cold / hot water outlet. The peripheral input / output circuit 13 controls a pump and a valve for transporting the refrigerant and inputs a flow rate of the cold and hot water. The communication circuit 15 exchanges information about the temperature and flow rate of the cold / hot water with the temperature controller of another cold / hot water generator. The central processing unit 14 sets the cold / hot water generator to which it belongs to from the information obtained through the communication circuit 15 and the control data stored by itself, in addition to the cold / hot water outlet temperature and the cold / hot water flow rate obtained by the circuit. The cool / hot water outlet temperature to be calculated is calculated, and the own cold / hot water generator is controlled through the above circuits based on the calculated temperature.

Regarding the temperature control of each cold / hot water generator,
The operation will be described by taking a cooling operation as an example. The central processing unit 14 of each temperature control device (4A, 4B, 4C) individually sets the target temperature of the chilled / hot water outlet temperature in the chilled / hot water generator to which it belongs according to the control flowchart shown in FIG. Ask for. Here, the target temperature of the cold / hot water supplied from the system in which three absorption-type cold / hot water generators are operated in parallel is Ts. Note that Ts is also a set value of the cold / hot water mixing temperature in the header portion.

In step s1, the chilled / hot water outlet temperature and the chilled / hot water flow rate of each machine, which are sent to each other by communication, are
The header cold / hot water mixing temperature Th is obtained by calculation.

Th = (T1 × Q1 + T2 × Q2 + T3 × Q3) ÷
(Q1 + Q2 + Q3) When n cold / hot water generators are connected in parallel and operated, the general formula is expressed as follows.

Th = ΣTi × Qi / ΣQi where i: 1 to n Ti: actual temperature of the cold / hot water outlet of the i-th unit Qi: flow rate of the cold / hot water outlet of the i-th unit The cold / hot water outlet set temperature (Tc) of the cold / hot water generator is determined based on the temperature Th. FIG. 4 shows a curve indicating the relationship between the header portion detected temperature (Th) and the cold / hot water outlet set temperature (Tc) at the header portion set temperature (here, Ts = 8 ° C.). The cold / hot water outlet set temperature Tc is calculated so as to reach the target temperature Ts. In FIG. 4, for example, assuming that the header section set temperature Ts is 8 ° C., the cold / hot water outlet set temperature Tc is 7 ° C. when the header section detected temperature Th is 9 ° C., and the Tc is lower when the Th is higher 10 ° C. ° C. When Th is 8 ° C or less, Tc
Is fixed at 8 ° C, and when Th is 10 ° C or more, Tc is set at 6 ° C.
(Upper capacity of cold / hot water generator). Note that Th
The -Tc (at Ts) curve is obtained in advance.

In step s3, the amount of combustion (%) consumed by the cold / hot water generator is determined from the cold / hot water outlet set temperature Tc obtained in step s2 and the detected value of the cold / hot water outlet temperature. FIG.
Shows a curve showing the relationship between the detected value of the cold / hot water outlet temperature and the combustion amount at each of the cold / hot water outlet set temperatures Tc. FIG. 5 shows, as an example, the combustion amount with respect to the detected value of the cold / hot water outlet temperature when the cold / hot water outlet set temperature Tc is 6 ° C., 7 ° C., and 8 ° C.
When c is 6 ° C and the cold / hot water outlet temperature detected value is 9 ° C, the combustion amount is 10
At 0%, the cold / hot water generator is PID controlled.

According to the above-described control, even if an abnormal machine with reduced capacity occurs in a plurality of cold / hot water generators operating in parallel,
In other normal machines, the cold / hot water outlet temperature is controlled to be lower than the original target temperature Ts (8 ° C. in the example),
Eventually, the mixing temperature in the header section itself is controlled to the original target temperature Ts (8 ° C.).

According to the present invention, not only the proportional combustion by PID, but also the control using the same concept can be applied to the control using the step control or the fuzzy control. In addition to the method based on the calculation based on the outlet temperature, a method in which a temperature detector is directly installed on the header section can be used.

Although the case where the cold / hot water generator is used for cooling has been described above, basically the same control system can be adopted when the cold / hot water generator is used for heating. That is, when the set temperature of the system (Ts)> the detected temperature of the header section (Th), the own cold / hot water outlet temperature set value Tc is increased from Ts in proportion to the magnitude of the temperature difference (Ts-Th), and Tc PID control is performed so as to increase the amount of combustion and increase the heating capacity as the air temperature is higher and the actual temperature of the cold / hot water outlet is lower. Further, the control method of the present invention is not limited to the absorption type chilled / hot water generator, but can also be adopted in a system constituted by a compression type chilled / hot water generator. What is necessary is just to control the rotation speed of the machine.

[0017]

According to the present invention, in a case where a plurality of cold / hot water generators are installed in parallel, not only when all the machines are in a steady state but also when some of the machines fail or the refrigerating capacity and the heating capacity decrease. However, the temperature of the cold / hot water to be supplied to the load side can be kept constant and can be supplied stably.

Further, the present invention does not require a central system control device for centrally controlling a plurality of cold / hot water generators, and independently controls each of the cold / hot water generators to provide a cold / hot water of a predetermined temperature. There is a feature that can respond to supply.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a cold / hot water supply system using a cold / hot water generator temperature control method according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a temperature control device of the cold / hot water generator.

FIG. 3 is a flowchart of control according to the present invention.

FIG. 4 shows a header portion temperature at a header portion set temperature.
It is a figure which shows the cold / hot water outlet set temperature (Tc) with respect to (Th).

FIG. 5 is a diagram showing a relationship between a cold / hot water outlet temperature and a combustion amount at a cold / hot water outlet set temperature Tc.

FIG. 6 is a diagram for explaining control of a conventional cold / hot water generator parallel operation system.

FIG. 7 is a diagram showing a relationship between a cold / hot water outlet temperature and a combustion amount in PID temperature control of the cold / hot water generator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1A, 1B, 1C Cold / hot water generator 2 Piping 3 Header 4A, 4B, 4C Temperature controller 6 Communication line 10 Cold / hot water temperature detection circuit 11 Each part temperature detection circuit 12 Combustion control circuit 13 Peripheral input / output circuit 14 Central processing unit 15 Communication circuit

Claims (5)

(57) [Claims] 1. A plurality of (n) cold / hot water generators are connected in parallel, cold / hot water from each machine is collected in a header section, and a header set temperature is set.
In the method of controlling the temperature of the chilled / hot water generator in the system supplied by (Ts), each chilled / hot water generator uses its own temperature control device to control the temperature (Tn) and flow rate of the chilled / hot water generated from each machine. Qn), and the header part temperature Th is calculated as Th = ΣTi × Qi / ΣQi (where i: 1 to n).
PID control to set its own cold / hot water outlet temperature set value Tc to a value apart from Ts in proportion to the magnitude of the temperature difference between h and Ts, and to increase the cooling or heating capacity of the cold / hot water generator. A method for controlling the temperature of a cold / hot water generator. 2. A method for controlling the temperature of a chilled / hot water generator in a system in which a plurality of (n) absorption type chilled / hot water generators are connected in parallel and chilled / hot water is collected from each machine into a header section and supplied at a header section set temperature (Ts). In each of the chilled / hot water generators, the temperature (Tn) and the flow rate (Qn) of the chilled / hot water generated from each machine are received by the temperature control device provided for each of them, and the header section temperature T
h is obtained as Th = ΣTi × Qi / ΣQi (where i: 1 to n), and when the system is in the cooling operation and Th> Ts,
The set value Tc of its own cold / hot water outlet temperature is made lower than Ts in proportion to the magnitude of the temperature difference (Th−Ts), and the combustion amount is increased as Tc is lower and the cold / hot water outlet actual temperature is higher, so that cooling is performed. A method for controlling the temperature of a cold / hot water generator, wherein PID control of combustion in the cold / hot water generator is performed so as to increase the capacity. 3. The relationship between the temperature difference (Th-Ts) and the set value Tc of the cold / hot water outlet temperature and the relationship between the set value Tc of the cold / hot water outlet temperature and the combustion are determined in advance. The method for controlling the temperature of a cold / hot water generator according to claim 1. 4. A method for controlling the temperature of a chilled / hot water generator in a system in which a plurality of (n) absorption type chilled / hot water generators are connected in parallel, and chilled / hot water is collected from each machine into a header section and supplied at a header section set temperature (Ts). In each of the chilled / hot water generators, the temperature (Tn) and the flow rate (Qn) of the chilled / hot water generated from each machine are received by the temperature control device provided for each of them, and the header section temperature T
h is obtained as Th = ΣTi × Qi / ΣQi (where i: 1 to n), and when the system is in the heating operation and Ts> Th,
The set value Tc of its own cold / hot water outlet temperature is raised above Ts in proportion to the magnitude of the temperature difference (Ts-Th), and the higher the Tc and the lower the cold / hot water outlet actual temperature, the more the combustion amount is increased and the heating is performed. A method for controlling the temperature of a cold / hot water generator, wherein PID control of combustion in the cold / hot water generator is performed so as to increase the capacity. 5. The relationship between the temperature difference (Ts−Th) and the set value Tc of the cold / hot water outlet temperature, and the relationship between the set value Tc of the cold / hot water outlet temperature and the combustion amount are determined in advance. The method for controlling the temperature of a cold / hot water generator according to claim 4.