JP2725883B2 - Control device for absorption refrigerator - Google Patents

Description

The present invention relates to an absorption refrigerator, and more particularly to a control device for an absorption refrigerator.

(B) Prior art For example, Japanese Patent Application Laid-Open No. 58-160778 discloses an absorber that detects a chilled water outlet temperature to control a heating amount to a generator, and detects an absorption liquid level in the generator. Controls the amount of dilute absorbent flowing from the chiller to the generator, and detects the cold water inlet temperature to determine the optimal value of either the heating amount of the generator for this temperature or the amount of dilute absorbent flowing to the generator. A control device for an absorption refrigerator that determines and controls either the heating amount or the amount of the diluted absorbing liquid based on this value is disclosed.

(C) Problems to be Solved by the Invention In the above-mentioned conventional technology, proportional control or PID control, which detects the level of the absorbing solution in the generator and controls the amount of the rare absorbing solution flowing from the absorber to the generator, is used. Was common.

However, the above control has a problem that the response is poor with respect to starting, stopping, gentle load fluctuation, sudden load fluctuation, or fluctuation of cooling water temperature.

An object of the present invention is to provide a control device of an absorption refrigerator having good responsiveness to starting, stopping, load fluctuation, and the like.

(D) Means for Solving the Problems The present invention relates to a control device for an absorption refrigerator having an evaporator, an absorber, an absorption liquid pump, a generator, and a pseudo-condenser connected to form a refrigeration cycle. The amount of operation of the absorption pump is fuzzy calculated using the deviation of the liquid level of the generator from the set value, the change rate of the liquid level of the generator, and the membership function set for each change rate of the heating amount of the generator. An arithmetic unit and a control unit for the absorbent pump for inputting the output of the arithmetic unit and increasing or decreasing the frequency of electric power supplied to the absorbent pump.

Further, the arithmetic unit fuzzy calculates the operation amount of the absorbent pump using a membership function set for the rate of change of the temperature of the generator and the rate of change of the inlet temperature of the cooling water.

(E) Action The refrigerating load changes and the heating amount control valve (1) of the generator (1)
When the opening degree of 7) changes, the number of revolutions of the absorbent pump (6) for sending the absorbent from the absorber (5) to the generator (1) is controlled by fuzzy logic operation based on human experience. In addition, the liquid level of the generator (1) is kept substantially constant, and it is possible to improve the heating efficiency of the absorbing liquid of the generator (1).

The level of the absorbing liquid in the generator (1), the amount of heating of the generator (1), the temperature of the generator (1), the inlet temperature of the cooling water, and the fuzzy rules stored in the storage device (31) And a fuzzy inference processor based on membership functions (3
In 0), the operation amount of the absorption pump (6) is calculated by fuzzy logic operation, and when the liquid level of the absorption liquid in the generator (1) changes, when the heating amount of the generator (1) changes, etc. The frequency of the electric power supplied to the absorbent pump (6) changes based on human experience, and the circulation of the absorbent with good responsiveness to starting, stopping, abrupt fluctuation of the refrigeration load, or gentle fluctuation. It is possible to control the amount.

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

FIG. 1 shows a double effect absorption refrigerator using water as a refrigerant and an aqueous solution of lithium bromide (LiBr) as an absorbent (solution).
(1) a high-temperature generator equipped with a burner (1B), (2) a low-temperature generator, (3) a pseudo-condenser, (4) an evaporator, (5)
Is an absorber, (6) is an absorbent pump, (7) and (8) are a low-temperature heat exchanger and a high-temperature heat exchanger, respectively (10) is a rare absorbent pipe, (11) is an intermediate absorbent pipe, 12) is a concentrated absorbent pipe, (13) is a refrigerant pipe, (14) is a refrigerant liquid down pipe, (15)
Are refrigerant liquid circulation pipes, 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). Reference numeral (16) denotes a fuel supply pipe connected to the burner (1B). A fuel control valve (heating amount control valve) is provided in the fuel supply pipe (16).
(17) is provided. Also, (20) is a chilled water pipe, and an evaporator heat exchanger (21) is provided in the middle of the chilled water pipe (20).
Is provided. Further, (22) is a cooling water pipe,
(6A) is an inverter for supplying electric power to the absorbent pump (6).

(23) is a control panel, (24) is a chilled water outlet temperature detector provided in the chilled water pipe (20), and the chilled water outlet temperature detector (24) and the fuel control valve (17) are connected to the control panel (23). )It is connected to the. The control panel (23) includes a microprocessor (25) and a control device (26) for the fuel control valve (17), an inverter control device (27), a feedback signal control device (28), and a generator liquid level detection. An apparatus (29) is provided. The microprocessor (25) is composed of a fuzzy inference processor (arithmetic unit) (30) and a control rule storage unit (31). (32) is an arithmetic unit,
(33) is a liquid level detector provided in the high temperature generator (1) to detect the level of the absorbing liquid, and (34) is a cooling water pipe (22) provided on the inlet side of the absorber (5). It is a water inlet temperature detector. The arithmetic unit (32) receives a signal from the chilled water outlet temperature detector (24) and calculates a deviation from a set value of the chilled water outlet.
The feedback signal detector (28) is connected to the fuel control valve (1
Input the signal of valve opening from 7) and calculate the valve opening by the arithmetic unit (3
Output to 2). The generator liquid level detector (29) receives a signal from the liquid level detector (33) and calculates the liquid level by an arithmetic unit (32).
Output to

The arithmetic unit (32) adjusts the opening degree of the fuel control valve (17) for a predetermined time (for example, one minute), the deviation of the liquid level of the high temperature generator (1) from the optimum value, and The rate of change of the liquid level for a predetermined time is calculated. The fuzzy inference processor (30) has a change rate of the opening of the fuel control valve (17) input from the arithmetic unit (32), a deviation of the liquid level of the high temperature generator (1) from the optimum value, and the high temperature generator (1). The fuzzy logic operation is performed based on the change rate of the liquid level of the liquid level for a predetermined time and the fuzzy rule and the membership function input from the storage device (31).

The storage device (31) stores, based on human experience, fuzzy rules necessary for fuzzy logic operation,
The ship function is stored. And the storage device (31)
A fuzzy rule of the operation amount of the fuel control valve (17) with respect to the deviation (eTo) from the set value of the chilled water outlet temperature is stored. Also, the deviation (eLg) of the liquid level of the high-temperature generator (1) from the optimum value (set value) shown in FIG.
Fuzzy rule of the operation amount (dIn) of the absorption pump (6) with respect to the operation amount (dIn) of the absorption pump (6) with respect to the change rate (dLg) of the liquid level of the high temperature generator (1) shown in FIG. d
In) and the fuzzy rule of the operation amount (dIn) of the absorbent pump (6) with respect to the change rate (dBk) of the opening degree of the fuel control valve (17) shown in FIG. 4 are stored. . Here, in FIG. 2, FIG. 3 and FIG.
PB (Positive Big) is positively large, PS (Positive Small) is positively small, ZR is zero, NS (Negative Small) is negatively small, NB
(Negative Big) means negatively large.

The storage device (31) has a membership function for qualitatively evaluating the deviation (eLg), the rate of change (dLg) and the rate of change (dBk) shown in FIGS. 5, 6, and 7. , And the operation amount (frequency) of the absorbent pump (6) shown in FIG.
The membership function of (dIn) is stored. Here, the membership function in FIG. 8 is a membership function for changing the operation amount of the absorbent pump (6) evaluated qualitatively to a quantitative value.

Then, the fuzzy logic operation is performed by the fuzzy inference processor (30) based on the liquid level of the high temperature generator (1) and the opening of the fuel control valve (17) according to each of the fuzzy rules and each of the membership functions. Then, the amount of operation of the absorbing liquid pump (6), that is, the amount of change in the frequency of the electric power supplied to the absorbing liquid pump (6) is obtained.

Hereinafter, the operation of the absorption refrigerator will be described. During operation of the absorption refrigerator, fuel is supplied to the high temperature generator (1), the burner (1B) burns, and the absorption liquid pump (6) and the refrigerant pump (15P) are operated. Then, the absorption liquid and the refrigerant circulate similarly to the conventional absorption refrigerator. And
The refrigerant liquid is sprayed to the evaporator heat exchanger (21) by the evaporator (4), and the cooled water whose temperature has decreased is supplied from the evaporator (4) to the load. The cooling water flowing through the cooling water pipe (22) deprives the heat in the absorber (5) and the condenser (3), and the temperature rises.

Further, a fuzzy logic processor (30) uses a fuzzy logic processor (30) based on the deviation of the chilled water outlet temperature of the evaporator (4) from the set value and the fuzzy rules and membership functions stored in the storage device (31). An operation is performed. And
An operation amount of the fuel control valve (17) is calculated, and an opening signal is output from the valve control device (26) to the fuel control valve (17).
Then, the opening of the fuel control valve (17) is controlled by the chilled water outlet temperature, the amount of heating of the high temperature generator (1) changes, and the chilled water outlet temperature is maintained at the set temperature.

Further, the feedback signal detection device (28) receives the opening signal as an analog signal from the fuel control valve (17), converts the signal into a digital signal, and outputs the digital signal to the arithmetic device (32). The arithmetic unit (32) calculates the rate of change of the opening of the fuel control valve (17) and outputs it to the fuzzy inference processor (30). The fuzzy inference processor (30) performs a fuzzy logic operation based on fuzzy rules and membership functions stored in the storage device (31). Here, the chilled water outlet temperature is increasing, and the rate of change of the opening of the fuel control valve (17) (dB)
If k) is, for example, 3% / min, the fuzzy inference processor (30) uses the fuzzy inference processor (30) based on the fuzzy rules in FIG. 4, the membership function in FIG. 7, and the rate of change (dBk). ) Performs a fuzzy logic operation as shown in FIG. Then, a membership value (M ₁ ) (shown by oblique lines in FIG. 9) of the operation amount (dIn) of the absorption liquid pump (6) based on the change rate (dBk) is obtained.

Further, the generator liquid level detecting device (29) receives the liquid level of the absorbing liquid from the liquid level detector (33), converts it into a digital signal, and outputs it to the arithmetic unit (32). The arithmetic unit (32) calculates a deviation (eLg) and a change rate (dLg) of the liquid level from the optimum value,
Output to the fuzzy inference processor (30). The fuzzy inference processor (30) is a storage device (31) shown in FIGS.
Fuzzy logic operation is performed based on the fuzzy rules shown in the figure and the membership functions shown in FIGS. 5, 6, and 8. Here, when the liquid level is lower than the set value by, for example, 4 mm, that is, when the deviation (eLg) is −4 mm, the fuzzy inference processor (30) as shown by the dashed line in FIG.
Performs fuzzy logic operation. Then, the deviation of the antecedent part (eL
From g) of -4 mm, the membership value (M ₂ ) of the manipulated variable (dIn) of the absorbent pump (6) (shown by hatching in FIG. 10) is obtained. When the rate of change of the liquid level (dLg) is, for example, -3.5 mm / min, the fuzzy inference processor (30) performs a fuzzy logic operation as shown by a dashed line in FIG. Then, the rate of change (dLg) of the antecedent part is -3.5 mm / min, and the membership value (M ₃ ) of the manipulated variable (dIn) of the absorbent pump (6) (shown by the hatched lines in FIG. 11). Is required.

And the fuzzy inference processor (30) is, for example, MAX
The OR of the membership values (M ₁ ), (M ₂ ), and (M ₃ ) shown in FIGS. 9, 10 and 11 is obtained by the center of gravity calculation method. The membership value of this logical sum is (M ₄ ) in FIG. 12, which is an outline when the membership values (M ₁ ), (M ₂ ), and (M ₃ ) are superimposed. Then, to determine the amount of operation of the absorption pump (6) from the average value of this member Ship value (M _4), i.e., the center of gravity (G _1). The fuzzy inference processor (30) outputs the operation amount to the inverter control device (27). The inverter control device (27) outputs to the inverter device (6A) a signal having a frequency obtained by adding the above operation amount to the frequency that has been output up to now. The inverter device (6A) supplies the power of the input frequency to the absorption liquid pump (6), and the rotation speed of the absorption liquid pump (6) increases. And the absorption liquid discharge amount of the absorption liquid pump (6) increases.

According to the above embodiment, the rate of change (dBk) of the opening of the fuel control valve (17), the deviation (eLg) of the liquid level of the high temperature generator (1) from the set value, and the rate of change of the liquid level (dLg) ) Performs a fuzzy logic operation based on human experience and controls the amount of operation of the absorbent pump (6), so that the amount of heating of the high-temperature generator (1) and the rapid and gentle changes in the liquid level can be adjusted. As a result, the discharge amount of the rare absorbing liquid from the absorbing liquid pump (17) changes, and the liquid level of the high-temperature generator (1) can be kept constant.
The heating efficiency of the absorption liquid of the high temperature generator (1) can be improved. Here, in the absorption refrigerator in which high-temperature and high-pressure steam is supplied to the high-temperature generator (1) from, for example, a gas engine generator, the absorption liquid pump (17) is operated based on human experience by fuzzy logic operation as described above. By controlling, it is possible to prevent a decrease in the liquid level and a decrease in the heat transfer area, and as a result, it is possible to improve the efficiency of the high-temperature generator.

Further, it is possible to prevent the absorption liquid from being mixed into the refrigerant vapor due to the rise in the liquid level of the high temperature generator (1), and to prevent the boil-off due to the decrease in the liquid level.

Hereinafter, a second embodiment of the present invention will be described. Note that, in the second embodiment, the configuration that is not particularly described is the same as that of the first embodiment, and a detailed description thereof will be omitted. (34) is a cooling water inlet temperature detector provided on the cooling water pipe (22) on the inlet side of the absorber (22), and (35) is a temperature detector provided on the high temperature generator (1). Then, each of the temperature detectors (34) and (35) outputs a temperature signal to the arithmetic unit (32). The arithmetic unit (32) calculates, for example, a rate of change (dTci) of the cooling water inlet temperature every minute and a change rate (dTg) of the high temperature generator temperature every minute, for example. Arithmetic unit (3
2) calculates the rate of change (dBk) of the opening degree of the fuel control valve, the deviation (eLg) of the liquid level of the high temperature generator (1), and the rate of change (dLg) in the same manner as in the first embodiment.

The control rule storage device (31) contains the fuzzy rules shown in FIGS. 2, 3, and 4 of the first embodiment, and FIGS. 5, 6, 7, and 8 of the first embodiment. Along with the membership function shown in the figure, the fuzzy rule for the rate of change of the cooling water inlet temperature (dTci) shown in FIG. 13 and the fuzzy rule for the rate of change of the high temperature generator temperature (dTg) shown in FIG. rule,
The membership function of the rate of change of the cooling water inlet temperature (dTci) shown in FIG. 15 and the membership function of the rate of change of the high temperature generator temperature (dTg) shown in FIG. 16 are stored.

During the operation of the absorption refrigerator, the rate of change (dBk) of the opening of the fuel control valve (17) is 3% / mi as in the first embodiment.
n, when the deviation (eLg) of the liquid level of the high temperature generator (1) is −4 mm and the rate of change of the liquid level (dLg) is −3.5 mm / min, FIG.
As shown in FIGS. 10 and 11, the fuzzy inference processor (30) performs a fuzzy logic operation and obtains each membership value. At this time, the arithmetic unit (32) calculates the cooling water inlet temperature change rate (dTci) based on the cooling water temperature on the inlet side of the absorber (5) detected by the cooling water inlet temperature detector (22). . Here, the temperature of the cooling water is gradually decreasing,
When the rate of change (dTci) is, for example, -1.7 ° C./min, the fuzzy inference processor (30) performs a fuzzy logic operation as shown by a dashed line in FIG. Then, from the rate of change (dTci) of -1.7 ° C / min, the operation amount (dIn) of the absorption liquid pump (6)
Of the membership (M ₉ ) (shown as hatched in FIG. 17). At this time, when the rate of change of the high temperature regenerator temperature (dTg) is, for example, -0.8 ° C./min, the fuzzy inference processor (30) performs a fuzzy logic operation as shown by a dashed line in FIG. Then, the change rate of the antecedent part (dT
From g) of -0.8 ° C / min, the membership value (M ₅ ) (shown by hatching in FIG. 18) of the manipulated variable (dIn) of the absorbent pump (6) is obtained.

And the fuzzy inference processor (30) is shown in FIG.
Calculate the logical sum of the membership values (M ₁ ), (M ₂ ), (M ₃ ), (M ₉ ), and (M ₁₀ ) shown in FIGS. 10, 11, 17, and 18. . The membership value of this OR is the contour of the superposition of the membership values (M ₁ ), (M ₂ ), (M ₃ ), (M ₉ ) and (M ₁₀ ), as shown in FIG. (M ₁₁ ). Then, an average of the maximum values of the membership values is obtained. The operating amount average value (barycenter) absorption pump from (G ₃₎ (6) is determined. This manipulated variable is output to the inverter control device (27). The inverter control device (27) outputs to the inverter device (6A) a signal having a frequency obtained by adding the operation amount to the frequency up to now. For this reason,
The frequency of the electric power supplied to the absorbing liquid pump (6) changes, and the discharge amount of the rare absorbing liquid from the absorbing liquid pump (6) changes.

Thereafter, similarly, the rate of change of the opening of the fuel control valve (17) (dB)
k), deviation of liquid level (eLg) and change rate of liquid level (dLg) of high temperature generator (1), change rate of cooling water inlet temperature (dTci), and change rate of temperature of high temperature generator (1) ( A fuzzy logic operation is performed by the fuzzy inference processor (30) based on (dTg), and the frequency of the power supplied to the absorbent pump (6) changes. For this reason, the discharge amount of the rare absorbing liquid from the absorbing liquid pump (6) changes, and the amount of the rare absorbing liquid sent to the high temperature generator (1) changes.

According to the above embodiment, the rate of change (dBk) of the opening of the fuel control valve (17), the deviation (eLg) of the liquid level of the high-temperature generator (1) and the rate of change of the liquid level (dLg), the cooling water inlet Temperature change rate (dTc
i) and the rate of temperature change (dTg) of the high-temperature generator (1), a fuzzy logic operation is performed based on human experience to control the operation amount of the absorbent pump (6). When the amount of heating, the liquid level of the high-temperature generator (1), the inlet temperature of the cooling water, or the temperature of the high-temperature generator (1) changes, it is sent to the high-temperature generator (1) based on human experience. The amount of the rare absorbing liquid changes, and the liquid level of the high-temperature generator (1) can be kept constant. As a result, the heating efficiency of the absorbing liquid in the high-temperature generator (1) can be improved.

In the first embodiment and the second embodiment,
The number of revolutions of the absorbent pump (6) was controlled based on a fuzzy logic operation to adjust the amount of the absorbent flowing from the absorber (5) to the high-temperature generator (1).
A control valve is provided in 1), and the opening degree of the control valve is controlled based on fuzzy logic operation to adjust the amount of the absorbent flowing from the high-temperature generator (1) to the absorber (5). The same operation and effect as the example can be obtained.

(G) Effects of the Invention The present invention provides a rate of change of the liquid level of the absorbing solution of the generator, a deviation of the level, a rate of change of the heating amount of the generator, a rate of change of the temperature of the generator,
The fuzzy logic operation is performed based on the rate of change of the inlet temperature of the cooling water, the fuzzy rule and the membership function to control the frequency of the electric power supplied to the absorbent pump, so that the liquid level of the generator changes. When this is done, it is possible to change the amount of circulation of the absorbing solution based on human experience, and as a result, the rate of change of the liquid level of the generator, the deviation of the liquid level, the rate of change of the heating amount, the rate of change of the temperature, and Regardless of the magnitude of the rate of change of the inlet temperature of the cooling water, the liquid level of the generator can be kept substantially constant, and the operation of the absorption refrigerator can be stabilized.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of an absorption refrigerator showing one embodiment of the present invention, and FIG. 2 is a deviation (eLg) of the liquid level of the absorbing liquid from an optimum value.
Diagram showing a fuzzy rule between and the operation amount (dIn),
Fig. 3 shows the rate of change of the liquid level of the absorbing solution (dLg) and the manipulated variable (dIn).
FIG. 4 shows a fuzzy rule between the rate of change (dBk) of the opening of the fuel control valve and the operation amount (dIn), and FIG. 5 shows a deviation ( Figure 6 defines the membership function of the fuzzy variable for eLg), Figure 6 defines the membership function of the fuzzy variable for the rate of change (dLg), and Figure 7 shows the function of the fuzzy variable for the rate of change (dBk). Figure defining the membership function, Figure 8 is the manipulated variable (frequency of the absorption pump) (dIn)
Figure 9 defines the membership function of the fuzzy variables for fuzzy variables. Fig. 9 is an illustration of fuzzy logic operation when the rate of change (dBk) is 3% / min. Fig. 10 is when the deviation (eLg) is -4mm. FIG. 11 is an explanatory diagram of the fuzzy logic operation of FIG.
Explanatory diagram of fuzzy logic operation when g) is -3.5 mm / min,
Figure 12 shows that the rate of change (dBk) is 3% / min and the deviation (eLg) is -4m.
m, the rate of change (dLg) is -3.5mm / min when the operating amount of the absorbent pump is calculated by the method of calculating the center of gravity of the MAX. Fig. 13 shows the rate of change (dTci) of the temperature of the generator and the operation. Fig. 14 shows the fuzzy rule between the quantity and the amount of cooling water inlet temperature (dTg) and the manipulated variable. Fig. 15 shows the rate of change (dTci). Figure 16 defines the membership function of the fuzzy variable. Figure 16 shows the rate of change (dT
Figure 17 defines the membership function of the fuzzy variable for g), FIG. 17 illustrates the fuzzy logic operation when the rate of change (dTci) is -1.7 ° C./min, and FIG. 18 illustrates the rate of change (dTci).
Illustration of fuzzy logic operation when g) is -0.8 ° C / min,
Figure 19 shows that the rate of change (dBk) is 3% / min and the deviation (eLg) is -4m.
m, change rate (dLg) is -3.5mm / min, change rate (dTci) is-
FIG. 4 is an explanatory diagram in a case where the operation amount of an absorbent pump is obtained when the rate of change (dTg) is 1.7 ° C./min and the rate of change (dTg) is 0.8 ° C./min. (1) High temperature generator, (2) Low temperature generator, (3)
... condenser, (4) ... evaporator, (5) ... absorber,
(6): Absorbent pump, (17): Fuel control valve (heating amount control valve), (30): Fuzzy inference processor (arithmetic device), (31): Storage device, (33) ... Liquid level detector,
(34)… Cooling water inlet temperature detector, (27)… Inverter control device, (35)… High temperature generator temperature detector.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tsuyoshi Okumura 2-18-18 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Inventor Masashi Izumi 2--18-18 Keihanhondori, Moriguchi-shi, Osaka (56) References JP-A-1-98864 (JP, A) JP-A-1-107066 (JP, A)

Claims (2)

(57) [Claims] An evaporator, an absorber, an absorbent pump, a generator,
In a control device of an absorption refrigerator in which a refrigeration cycle is formed by connecting a refrigerator and a pseudo-condenser, the deviation of the liquid level of the generator from the set value, the rate of change of the liquid level of the generator, the amount of heating of the generator A fuzzy calculation of the amount of operation of the absorbent pump using a membership function set for each rate of change of the rate of change, and an increase / decrease in the frequency of the power supplied to the absorbent pump by inputting the output of the arithmetic device A control device for an absorption chiller, comprising: a control device for an absorption liquid pump that performs the control. 2. The computing device further fuzzy calculates the operation amount of the absorbent pump using a membership function set for the rate of change of the temperature of the generator and the rate of change of the inlet temperature of the cooling water. The control device for an absorption refrigerator according to claim 1, wherein: