JPH0436558A - Control device for absorbing type refrigerator - Google Patents

Abstract

PURPOSE:To improve a stability at a cold water outlet temperature in respect to a load variation by a method wherein as an external condition, a difference from a set value of the cold water outlet temperature is applied, and a heating amount of a generator is controlled under a fuzzy inference in response to a fuzzy rule and a membership function defined between the difference and the heating amount of the generator. CONSTITUTION:An evaporator 4, an absorbing device 5, a high temperature generator 1 and a condensor 3 and the like are connected to each other so as to form a refrigera tor cycle. A control device for an adsorbing type refrigerator for use in controlling a heating amount of the high temperature generator 1 in response to external conditions is operated such that as the external condition, the deviation from the set value of the cold water outlet temperature is applied. A membership function and a fuzzy rule are defined between the difference and the heating amount of the high temperature generator 1. The heating amount of the high temperature generator 1 is controlled under a fuzzy inference in response to the fuzzy rule and the membership function. In the event that the cold water outlet temperature is higher than the set value, the heating amount is gradually varied and in turn when the cold water outlet temperature is lower than the set value, the heating amount is rapidly varied.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to an absorption refrigerator (including an absorption chiller/heater), and particularly to a control device for an absorption refrigerator.

(b) Conventional technology For example, Japanese Patent Application Laid-Open No. 58-160778 discloses that the amount of heating to the regenerator is controlled by detecting the cold water outlet temperature, and the absorption liquid level in the regenerator is detected to control the amount of heating to the absorber. In addition to controlling the amount of diluted absorbent flowing from the inlet to the regenerator, the system also detects the cold water inlet temperature and determines the appropriate value for either the heating amount of the regenerator or the amount of diluted absorbent flowing to the regenerator for this temperature. An absorption refrigerating machine control device has been disclosed which calculates this value and controls either the amount of heating or the amount of dilute absorption liquid based on this value.

(8) Problems to be Solved by the Invention In the above-mentioned conventional techniques, proportional control or PID control in which the amount of heating of the regenerator is controlled by detecting the cold water outlet temperature has been common.

Further, in an absorption refrigerator, the relationship between the cold water outlet temperature and the refrigeration capacity (refrigeration capacity) is generally as shown in FIG. As is clear from Fig. 10, when the chilled water outlet temperature is higher than the set value, the refrigeration capacity gradually increases as the chilled water outlet temperature increases, and when it is lower than the set value, the chilled water outlet temperature increases. Refrigeration capacity decreases rapidly as the temperature decreases.

However, in the conventional PID control or proportional control, whether the chilled water outlet temperature is higher or lower than the set value,
Since the manipulated variable (opening degree) of the fuel control valve with respect to the deviation of the cold water outlet temperature from the set value is linear, the manipulated variable of the fuel control valve is similarly controlled. For example, if the side lower than the set value is controlled as well as the side higher than the set value (10th
It is shown by a dashed line in the figure. ), when the chilled water outlet temperature becomes lower than the set value, the manipulated variable is delayed in response to the drop in the chilled water outlet temperature, and there is a risk that the chilled water outlet temperature will drop too far, resulting in a significant drop. In addition, if the side higher than the set value is controlled in the same way as the side lower than the set value (indicated by the two-dot chain line in Figure 10), when the chilled water outlet temperature becomes higher than the set value, The manipulated variable would be too fast relative to the temperature rise, and there was a risk that the cold water outlet temperature would drop significantly and overshoot downward.

Furthermore, when adopting fuzzy reasoning to control an absorption chiller, the deviation of the chilled water outlet temperature from the set value is set as eTO, and the operating amount of the fuel control valve or steam control valve of the high temperature generator is set as KQ.
In the conventional fuzzy control, the above deviation (eIo
) is represented by 4150, and the membership function of the manipulated variable (KQ) is represented by FIG. Also, the manipulated variable (KQ) for the deviation (eTo)
The fuzzy rule is shown in Figure 3. When each membership function and fuzzy rule are defined as above, the membership function and fuzzy rule are symmetrical on the positive side and negative side of the deviation, so the above PID control or proportional control Similarly, there is a risk that the cold water outlet temperature will go too far downward. Here, in Figs. 3, 4, and 6, P B (Po5itive Big)
is exactly large, P M (Po5itive Medium
) is exactly medium, PS (Po5itive Small
) is exactly small, ZR is zero, NS (Negative
Small ) is negatively small, N M (Negative
eMedium) is negative medium, N B (Negati
ve Big ) is negatively large.

An object of the present invention is to prevent the cold water outlet temperature from falling too much when the load fluctuates, and to improve the stability of the cold water outlet temperature against load fluctuations.

(d) Means for Solving the Problems In order to solve the above problems, the present invention connects an evaporator (4), an absorber (5), a high temperature generator (1), a condenser (3), etc. In an absorption chiller control device that forms a refrigeration cycle and controls the heating amount of the high temperature generator (1) based on external conditions, the deviation from the set value of the chilled water outlet temperature is used as the external condition, and this deviation and high temperature A membership function and a fuzzy φ rule are defined between the heating amount of the generator (1) and the heating amount of the high temperature generator (1) is controlled by fuzzy inference based on this fuzzy rule and membership function. death,
To provide a control device for an absorption chiller that changes the heating amount slowly when the cold water outlet temperature is higher than the set value, and rapidly changes the heating amount when the cold water outlet temperature is lower than the set value. be.

Also, the deviation of the chilled water outlet temperature from the set value and the high temperature generator (1
) between the operation amount of the heating amount control valve (17) and the operation amount of the heating amount control valve (17).
A ship function or fuzzy rule is defined, and if the cold water outlet temperature is higher than the set value, the manipulated variable is gradually changed,
A membership function or fuzzy function is used to rapidly change the manipulated variable when the chilled water outlet temperature is lower than the set value.
Provided is a control device for an absorption refrigerator that configures rules and performs fuzzy inference based on the membership function or fuzzy rules to control a heating amount control valve (17) of a high temperature generator (1). It is something to do.

Furthermore, the member stipulates that the heating amount of the high temperature generator (1) in response to the deviation of the chilled water outlet temperature from the set value is changed gradually when the chilled water outlet temperature is higher than the set value, and rapidly changed when the chilled water outlet temperature is lower than the set value. - A storage device (28) that stores Ship functions and fuzzy rules, and a heating amount control valve (17) that performs fuzzy inference based on the cold water outlet temperature and the membership functions and fuzzy rules of the storage device (28). The present invention provides a control device for an absorption refrigerator, which is equipped with a fuzzy inference processor (27) that calculates the manipulated variable.

(f) Effect When the absorption chiller is operating, fuzzy inference is performed based on the chilled water outlet temperature, membership function, and fuzzy rules, and if the chilled water outlet temperature is higher than the set value, the high temperature generator (1) When the heating amount of the high temperature generator (1) changes gradually and the cold water outlet temperature is lower than the set value, the heating amount of the high temperature generator (1) changes rapidly, making it possible to control the heating amount in accordance with the characteristics of the absorption chiller. This makes it possible to stabilize the cold water outlet temperature.

Further, when the absorption chiller is operating, fuzzy inference is performed based on the cold water outlet temperature, the membership function, and the fuzzy rule, and the operation amount of the heating amount control valve (17) is adjusted.
If the chilled water outlet temperature is higher than the set value, the heating amount control valve (
17) changes slowly and the chilled water outlet temperature is lower than the set value, the operating amount of the heating amount control valve (17) changes rapidly, and the heating amount of the high temperature generator (1) is absorbed and refrigerated. It can be controlled according to the characteristics of the machine, making it possible to stabilize the chilled water outlet temperature.

Further, fuzzy inference is performed by a fuzzy inference processor (28) based on the cold water outlet temperature, the membership function and fuzzy rules stored in the storage device (28), and the fuel control valve of the high temperature generator (1) is The manipulated variable (17) is determined, and the heating amount of the high temperature generator (1) can be controlled in accordance with the characteristics of the absorption refrigerator, making it possible to stabilize the cold water outlet temperature.

(F) Example Hereinafter, a first example of the present invention will be described in detail based on the drawings.

Figure 1 shows water as the refrigerant and lithium bromide (L) as the absorbent (solution).
iar) shows a double-effect absorption refrigerator using aqueous solution, (1) is a high temperature generator with a burner (IB), (2
) is a low temperature generator, (3) is a condenser, (4) is an evaporator, (
5) is the absorber, (6> is the absorption liquid pump, (7), (
8) are a low temperature heat exchanger and a high temperature heat exchanger, respectively, (10
) is the dilute absorption liquid piping, (11) is the intermediate absorption liquid piping, (12) is the
) is a concentrated absorption liquid pipe, (13) is a refrigerant pipe, (14) is a refrigerant liquid flow pipe, and (15) is a refrigerant liquid circulation pipe, each of which is connected as shown in FIG. A refrigerant pump (15P) is provided in the middle of the refrigerant liquid circulation pipe (15), and (16) is a fuel supply pipe connected to the burner (IB). A fuel control valve (heating amount control valve) (17) is provided in the middle of the pipe. Also, (20) is a cold water pipe, and an evaporator heat exchanger (21) is installed in the middle of this cold water pipe (20). is provided.Kirani (22) is a cooling water pipe.

(23) is a control panel, (24) is a chilled water outlet temperature detector installed in the chilled water pipe (20), and this chilled water outlet temperature detector (24) and fuel control valve (17) are connected to the control panel (23).
)It is connected to the. The control panel (23) is provided with a microprocessor (25) and a control device (26) for the fuel control valve (17). The microprocessor (25) is a fuzzy inference processor (arithmetic unit)
(27) and a control rule storage device (28). The fuzzy inference processor <27> uses the deviation of the chilled water outlet temperature from the set value to control the fuel control valve (17).
Perform logical calculations on the manipulated variables and apply the obtained manipulated variables to the control device! (26
). The control device (26) controls the opening degree of the fuel control valve (17) based on the manipulated variable. In this embodiment, the fuzzy inference processor (27) to the fuel control valve (1)
7) is output. The control rule storage device (28) is a storage device that stores control rules (fuzzy rules) and membership functions necessary for fuzzy logic operations executed by the fuzzy inference processor (27). Further, (30) is a calculation device, and the calculation device 4 calculates the deviation of the cold water outlet temperature from the set value based on the temperature data of the cold water outlet temperature detector (24).

The fuzzy logic operation for determining the opening degree of the fuel control valve (17) is performed based on control rules and membership functions. Regarding the above control rules, the deviation (eTo) of the chilled water outlet temperature from the set value is determined based on human experience.
) and the manipulated variable (opening degree) of the fuel control valve (17) (KQ)
A control rule as shown in FIG. 2 is defined between the two, and this control rule is fully stored in the storage device (28). Second
In the figure, P M (Positive Medium
) is exactly medium, N M (Negative Mediu
m ) is negatively inside. The deviation from Figure 2 is PB (
In the case of a true dog), the manipulated variable is not set to PB but is set to PM (just a medium) to suppress the manipulated amount. Also, the deviation is NS (negative Ni/J1)
In this case, instead of setting the manipulated variable to NS, the manipulated variable is set to NM (medium to A) and the manipulated variable is increased.

In addition, a membership function, that is, a fuzzy variable PB, is used to qualitatively evaluate the deviation of the chilled water outlet temperature from the set value.
, PS, ZR, NS, NB (7) The membership functions are shown in FIG.

In addition, a membership function for converting the operational amount of the fuel control valve (17), which has been qualitatively evaluated, into a quantitative value, that is, a fuzzy variable F for the opening degree of the fuel control valve (17).
B, PM, PS, ZR, NS, NM.

The membership function of NB is shown in FIG.

Then, fuzzy logic operations are performed in the fuzzy inference processor (27) based on the above control rules, each membership function, and the deviation from the set value of the chilled water outlet temperature, and the operation amount of the fuel control valve (17) is is required.

The operation of the absorption refrigerator will be explained below. When the absorption refrigerator is in operation, the burner (IB) burns, and the absorption liquid pump (6) and refrigerant pump (15F) are fully operated, and the absorption liquid and refrigerant circulate as in the conventional absorption refrigerator.

Then, the refrigerant liquid is transferred to the evaporator heat exchanger (21) in the evaporator (4).
), and the cooled water whose temperature has been reduced is supplied to the load from the evaporator (4).

During operation of the absorption chiller, for example, if the chilled water outlet temperature is lower than the set value, the control rule shown in FIG. Even if the deviation is small, the manipulated variable becomes large, and the fuzzy inference processor (27) outputs a signal of the large manipulated variable to the control device (26).

Here, if the deviation is, for example, -1.5 DEG C., fuzzy inference is performed as shown by the dashed line in FIG. 7, and the membership value (A) for the manipulated variable is determined. Then, the operation amount of the fuel control valve (17) is determined from the center of gravity (G, ) of this membership value (A). Even when the chilled water outlet temperature slightly decreases from the set value, the membership value of the manipulated variable is determined by the fuzzy variables ZR, NM, and the manipulated variable of the fuel control valve (17) decreases as the chilled water outlet temperature decreases. Decrease rapidly. For this reason, the fuel control valve (17
) changes rapidly in response to changes in refrigeration load. Furthermore, when the chilled water outlet temperature is higher than the set value, the control rule shown in FIG. ) outputs a signal with a small manipulated variable. If the deviation is, for example, 1.4° C., fuzzy inference is performed as shown by the two-dot chain line in FIG. 7, and the membership value (B) for the manipulated variable is determined. Then, the operating amount of the fuel control valve (17) is determined from the center of gravity (G8) of this membership value. Even when the chilled water outlet temperature decreases significantly, the membership value of the manipulated variable is determined by the fuzzy variables PM and PS, and the manipulated variable of the fuel control valve (17) gradually increases as the chilled water outlet temperature rises. Therefore, the opening degree of the fuel control valve (17) changes gradually in accordance with changes in the refrigeration load.

According to the first embodiment, the control rule for the operation amount of the fuel control valve (17) with respect to the deviation of the chilled water outlet temperature from the set value is set as shown in FIG. 2, and the chilled water outlet temperature is set to the set value. When the deviation is significantly higher, that is, the deviation is PB (positively large), the manipulated variable is set to PM (positively medium), and when the chilled water outlet temperature is slightly lower than the set value, that is, when the deviation is NS (negatively small). Since the manipulated variable is set to NM (negative medium), the manipulated variable of the fuel control valve (17) based on fuzzy reasoning is changed gradually when the chilled water outlet temperature is higher than the set value, and rapidly when the cold water outlet temperature is lower than the set value. The high temperature generator (
1) The amount of heating can be adjusted to avoid excessively low cold water outlet temperature, even when load fluctuations occur.
It can provide a stable supply of cold water.

Hereinafter, a second embodiment of the present invention will be described in which a difference is provided in the membership value depending on whether the deviation of the cold water outlet temperature from the set value is positive or negative. The storage device (28) includes
Membership functions of fuzzy variables FB, PS, ZR, NS, and NB for the deviation of the cold water outlet temperature from the set value shown in FIG. 5 are stored. In addition, the storage device has
77 variables PB, PM, PS, ZR, NS, N for the operation amount (opening degree) of the fuel control valve (17) shown in FIG.
The membership functions of M and NB and the control rules shown in FIG. 3 are stored. As is clear from Figure 5, when the chilled water outlet temperature is higher than the set value, that is, the deviation from the set value is positive, and when the chilled water outlet temperature is lower than the set value, that is, when the deviation is negative, the member・Differences are made in the label determination stage of the ship function. When the deviation is, for example, -0.8 DEG C., fuzzy inference is performed as shown in FIG. 8, and the membership value (C) for the manipulated variable of the fuel control valve (17) is determined.

And the center of gravity (G, ) of this membership value (C)
The amount of operation is determined from . Then, when the cold water outlet temperature falls below the set value, the manipulated variable rapidly decreases. Therefore, the opening degree of the fuel control valve (17) changes rapidly in response to changes in the refrigeration load. Further, when the above deviation is, for example, 0.8°C, fuzzy inference is performed as shown in FIG.・Ship value (
The amount of operation is determined from the center of gravity (G4) of D). Then, when the cold water outlet temperature rises above the set value, the manipulated variable increases gradually. Therefore, the degree of opening of the °C fuel control valve (17) changes gradually in response to changes in the refrigeration load.

According to the second embodiment, a difference is provided at the stage of label determination, and when the deviation is positive, the evaluation of the absolute value of the deviation is small even if the deviation is large, and when the deviation is negative, the evaluation of the absolute value of the deviation is small. The evaluation of the absolute value of the deviation is large, so the operation amount of the fuel control valve (17) after the fuzzy logic operation changes gradually when the chilled water outlet temperature is higher than the set value, and when it is lower than the set value. Change rapidly. As a result, the heating amount of the high temperature generator (1) can be adjusted according to the characteristics of the absorption chiller in response to increases and decreases in the chilled water outlet temperature, and the chilled water is stabilized by avoiding the chilled water outlet temperature from falling too low. and can be supplied.

In each of the above embodiments, an absorption refrigerator having a high-temperature generator (1) equipped with a burner (IB) has been described. In absorption refrigerators, the amount of steam supplied to the high-temperature generator is controlled by adjusting the opening degree of the steam control valve.
Similar effects can be obtained by dividing the opening degree of the steam control valve into the iW node using fuzzy reasoning in the same manner as the fuel control valve of the above embodiment. Furthermore, similar effects can be obtained in an absorption refrigerating machine by controlling the fuel control valve based on fuzzy reasoning as in the above embodiment when cold water is supplied. When Kei et al. performed fuzzy inference based on the control rule shown in Fig. 2 and the member Φship function shown in Figs. 5 and 6 to find the operating amount of the fuel control valve (17), Furthermore, the cold water outlet temperature can be stabilized.

(G) Effects of the Invention The present invention is a control device for an absorption chiller configured as described above, which uses the deviation of the chilled water outlet temperature from the set value, and creates a relationship between this deviation and the heating amount of the generator. - Define a ship function and a fuzzy rule, and use fuzzy inference based on this fuzzy rule and membership function to gradually change the heating amount of the generator when the cold water outlet temperature is higher than the set value. If the temperature is low, the heating amount of the generator can be rapidly changed, so if the chilled water outlet temperature becomes lower than or higher than the set value, it is possible to prevent the chilled water outlet temperature from going too low. It can be stabilized.

In addition, the membership function or fuzzy rule between the chilled water outlet temperature and the manipulated variable of the heating amount control valve of the generator is set by rapidly changing the manipulated variable when the chilled water outlet temperature is lower than the set value. If the chilled water outlet temperature is higher than the set value, the heating amount control valve is controlled by using fuzzy reasoning. By optimally controlling the opening degree of the valve and preventing the cold water outlet temperature from going too low, the cold water outlet temperature can be stabilized.

Kei et al. developed a membership function and fuzzy rule that set the heating amount of the generator to change gradually when the cold water outlet temperature is higher than the set value, and to change the heating amount rapidly when it is lower. is stored in the storage device, and the operation amount of the heating amount control valve is determined by the arithmetic unit through fuzzy inference based on the membership function and fuzzy rules mentioned above, so the operation amount is adjusted according to the characteristics of the absorption chiller. As a result, the cold water outlet temperature can be stabilized.

[Brief explanation of drawings]

Fig. 1 is a circuit configuration diagram of an absorption refrigerator showing an embodiment of the present invention, Figs. 2 and 3 are explanatory diagrams of fuzzy rules for deviations from set values, and Figs. 4 to 6 are members of the - An explanatory diagram of the Ship function, FIGS. 7 to 9 are explanatory diagrams of fuzzy inference, and FIG. 10 is a diagram of the relationship between chilled water outlet temperature and refrigeration capacity (refrigeration capacity). (1)...High temperature generator, (3)...Condenser, (
4)...Evaporator, (5>...Absorber, (17)
...Fuel control valve (heating amount control valve), (27)...
Fuzzy inference processor, (28)...storage device.

Claims (1)

[Claims] 1. A control device for an absorption refrigerator that connects an evaporator, absorber, generator, condenser, etc. to form a refrigeration cycle, and controls the heating amount of the generator according to external conditions, Using the deviation of the chilled water outlet temperature from the set value as the above external condition, a membership function and fuzzy rule are defined between this deviation and the heating amount of the generator, and this fuzzy rule and membership function are Based on this, the heating amount of the generator is controlled by fuzzy inference, and when the cold water outlet temperature is higher than the set value, the heating amount is gradually changed, and when the cold water outlet temperature is lower than the set value, the heating amount is changed. A control device for an absorption refrigerator that is characterized by rapid changes. 2. In an absorption refrigerating machine control device that connects an evaporator, absorber, generator, condenser, etc. to form a refrigeration cycle, and controls the heating amount control valve of the generator according to external conditions, the above-mentioned external conditions The deviation of the chilled water outlet temperature from the set value is used for The above membership function is configured to change the amount slowly, and when the cold water outlet temperature is lower than the set value, the operation amount is changed rapidly, and the membership function is generated by fuzzy inference based on this membership function. 1. A control device for an absorption chiller, characterized in that it controls a heating amount control valve of a refrigerator. 3. In an absorption refrigerating machine control device that connects an evaporator, absorber, generator, condenser, etc. to form a refrigeration cycle, and controls the heating amount control valve of the generator according to external conditions, the above-mentioned external conditions Using the deviation of the chilled water outlet temperature from the set value, a fuzzy rule is established between this deviation and the operation amount of the heating amount control valve, and if the chilled water outlet temperature is higher than the set value, the heating amount is gradually reduced. The fuzzy rule is configured to rapidly change the heating amount when the cold water outlet temperature is lower than the set value, and the heating amount control valve is controlled by fuzzy reasoning based on this fuzzy rule. A control device for an absorption refrigerator characterized by the following. 4. In an absorption refrigerating machine control device that connects an evaporator, absorber, generator, condenser, etc. to form a refrigeration cycle, and controls the heating amount control valve of the generator according to external conditions, the above-mentioned external conditions A member configured to use the deviation of the chilled water outlet temperature from a set value to change the heating amount of the generator in response to this deviation gradually when the chilled water outlet temperature is higher than the set value, and rapidly when it is lower than the set value. - A storage device that stores ship functions and fuzzy rules, and a calculation device that calculates the operation amount of the heating amount control valve by performing fuzzy inference based on the cold water outlet temperature and the membership functions and fuzzy rules of the storage device. A control device for an absorption refrigerator, characterized by comprising: