JPH07190540A - Control device of absorption refrigerating machine - Google Patents

Abstract

PURPOSE:To enable execution of an operation of high energy efficiency by controlling the quantity of heating of a generator on the basis of the temperature on the evaporator outlet side of cold water and by controlling also the flow rate of the cold water on the basis of the temperature on the evaporator inlet side of the cold water. CONSTITUTION:When the temperature on the evaporator 5 outlet side of cold water measured by a temperature sensor 23 falls below 7 deg.C, the quantity of refrigerant regenerated by evaporation and separation in a high-temperature regenerator 1 and a low-temperature regenerator 3 decreases automatically. Since a refrigerant liquid supplied from a refrigerant distributor 6 to an evaporator 5 decreases consequently, the degree of cooling of the cold water by an evaporation latent heat of the refrigerant transferred through the tube wall of a heat transfer tube 18 lowers and the temperature on the evaporator outlet side of the cold water rises and returns to 7 deg.C. When the temperature on the evaporator outlet side of the cold water exceeds 7 deg.C, to the contrary, the quantity of the refrigerant regenerated in the high- temperature regenerator 1 and the low-temperature regenerator 3 increases automatic ally and the temperature on the outlet side returns to 7 deg.C. When the temperature on the evaporator inlet side is lower than 12 deg.C, besides, the number of revolutions of a cold water pump 19 is reduced, while it is increased when the temperature exceeds 12 deg.C, and thus the temperature is kept at 12 deg.C approximately.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a controller for an absorption refrigerator.

[0002]

2. Description of the Related Art Absorption refrigerators have the feature that energy consumption can be reduced as compared with refrigerators of the type that compresses and expands a refrigerant, and in recent years, it has been remarkably popular in large-scale cooling and heating devices.

Conventionally, an absorption refrigerating machine having such a feature is so arranged that the evaporator outlet side temperature T1 of the cold water taken out through the heat transfer tube inside the evaporator becomes a predetermined temperature (for example, 7 ° C.). The heating amount of the generator was controlled (see FIG. 5). Further, the flow rate of the cold water supplied to the cooling load is usually constant, and when controlling the flow rate of the cold water, for example, it was controlled according to the number of operating indoor units.

[0004]

However, in the above conventional control method, the heating amount control of the generator is controlled by the refrigerator side,
Since the operation of the chilled water pump was independently controlled on the indoor unit side, it was not always the optimal control from the overall viewpoint, and it became a problem for further energy saving. However, the solution to this point was an issue.

[0005]

In order to solve the above-mentioned problems of the prior art, the present invention determines the heating amount of the generator based on the evaporator outlet side temperature of the cold water taken out via the heat transfer tube inside the evaporator. Control of an absorption refrigerator having a heating amount control function for controlling, and a flow rate control function for controlling the flow rate of the cold water based on the evaporator inlet side temperature of the cold water that returns to the heat transfer tube after finishing the cooling operation. A device,

[0006] A heating amount control function for controlling the heating amount of the generator based on the evaporator outlet side temperature of the cold water taken out through the heat transfer pipe inside the evaporator, and the cooling action is returned to the heat transfer pipe. When the temperature on the evaporator inlet side of the cold water is lower than a predetermined temperature, the flow rate of the cold water is decreased, and when the temperature on the evaporator inlet side of the cold water exceeds the predetermined temperature, based on the temperature on the evaporator inlet side. It is an absorption chiller control device having a control function of increasing the flow rate of the cold water and a control function of keeping the flow rate of the cold water at a lower limit flow rate or more.

[0007]

Since the device controls the heating amount of the generator based on the temperature of the cold water on the evaporator outlet side and controls the flow rate of the cold water on the basis of the temperature of the cold water on the evaporator inlet side, the cool water on the evaporator inlet side is controlled. When the cooling load decreases when the temperature decreases, the rotation speed of the cold water pump decreases because the flow rate of the cold water decreases. This makes it possible to significantly reduce power consumption,
Energy efficient operation is performed.

Further, the flow rate of the cold water is kept above the lower limit flow rate, and even when the cooling load is significantly reduced, the cold water above the lower limit flow rate circulates in the evaporator, and the freezing of the evaporator is avoided.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in more detail with reference to the drawings. FIG. 1 is a schematic configuration diagram of an absorption refrigerator using, for example, water as a refrigerant and a lithium bromide (LiBr) solution as an absorbing liquid (solution), where 1 is equipped with a combustion device 2 for gas, kerosene, etc. A high temperature regenerator (corresponding to a generator referred to in the claims together with a low temperature regenerator described below) that generates a refrigerant vapor by heating a liquid and concentrates it into an intermediate liquid, 3 is the intermediate liquid due to the refrigerant vapor Is a low temperature regenerator for heating to a concentrated liquid, 4 is a condenser for cooling and condensing the refrigerant vapor supplied from the low temperature regenerator 3, and 5 is a refrigerant distributor 6 for spraying and dropping the refrigerant liquid. An evaporator for evaporating, 7 is an absorber for absorbing the refrigerant vapor flowing from this evaporator into the concentrated liquid supplied from the low temperature regenerator 3, and maintaining the inside of the container at a low pressure, 8 is a low temperature heat exchanger, and 9 is It is a high temperature heat exchanger, and these are the intermediate liquid pipe 10, the concentrated liquid pipe 11, and the suction pipe. A diluting liquid pipe 13 having a liquid pump 12, a refrigerant conduit 14 having on-off valves 14a and 14b, a refrigerant liquid pipe 15, and a refrigerant circulating pipe 17 having a refrigerant pump 16 are connected to each other to form a circulation cycle of the refrigerant and the absorbing liquid. Has formed,

A heat transfer tube 18 provided inside the evaporator 5.
The cold water cooled by the latent heat of vaporization of the refrigerant through the pipe wall can be supplied to a required indoor heat exchanger (not shown) serving as a cooling load by the cold water pipe 20 having the cold water pump 19. Further, reference numeral 21 is a cooling water pipe that is piped through the inside of the absorber 7 and the condenser 4, and the device configuration itself of these is well known.

The control device of the present invention comprises a controller 22 having necessary functions such as storage, calculation and comparison functions, and temperature sensors 23 and 24 installed at the inlet and outlet of the evaporator 5 of the cold water pipe 20. , The opening V of the fuel control valve 2a is controlled based on the evaporator outlet side temperature T1 of the cold water measured by the temperature sensor 23, and the cold water pump 19 based on the evaporator inlet side temperature T2 of the cold water measured by the temperature sensor 24. Control the rotation speed N of
This controls the thermal power of the combustion device 2 and the flow rate of the cold water that flows through the cold water pipe 20 and is supplied to the cooling load.

A specific example of the control of the control device according to the present invention will be described. When the temperature T1 of the cooler evaporator outlet side T1 measured by the temperature sensor 23 becomes lower than a predetermined temperature, for example, 7 ° C. It is provided so that the opening V of the fuel control valve 2a is reduced to reduce the thermal power of the combustion device 2, and when it becomes higher than 7 ° C., the opening V of the fuel control valve 2a is increased to increase the thermal power of the combustion device 2. There is.

Therefore, when the temperature T1 of the cold water evaporator outlet side falls below 7 ° C., the high temperature regenerator 1 and the low temperature regenerator 3 are placed.
The amount of refrigerant produced by evaporation and separation is automatically reduced,
As a result, the amount of the refrigerant liquid supplied from the refrigerant distributor 6 to the evaporator 5 decreases, so that the degree to which the cold water is cooled by the latent heat of evaporation of the refrigerant via the tube wall of the heat transfer tube 18 decreases, and the cold water evaporator outlet The side temperature T1 starts to rise to a predetermined temperature of 7
Return to ℃.

On the contrary, the temperature T1 of the cold water evaporator outlet side is 7 ° C.
When the temperature rises above, the amount of the refrigerant generated in the high temperature regenerator 1 and the low temperature regenerator 3 automatically increases, so that the refrigerant liquid supplied from the refrigerant distributor 6 to the evaporator 5 increases. The degree to which the cold water is cooled via the heat transfer tube 18 increases, and the evaporator outlet side temperature T1 of the cold water starts to decrease and returns to a predetermined temperature of 7 ° C.

That is, if a slight fluctuation is ignored, the controller 22 sets the opening degree V of the fuel control valve 2a to 0 to 10 based on the evaporator outlet side temperature T1 of the cold water measured by the temperature sensor 23.
By controlling between 0%, the thermal power of the combustion device 2 is controlled, and thereby the amount of latent heat of vaporization of the refrigerant in the evaporator 5 is controlled. Therefore, as shown by the solid line in FIG.
The evaporator outlet side temperature T1 of the cold water is maintained at a predetermined temperature, in this case 7 ° C., except immediately after the start of cooling in which the evaporator side temperature T2 of the cold water is higher than a predetermined 12 ° C.

Immediately after the start of cooling, the temperature T2 at the evaporator inlet side of the cold water which has finished the cooling operation and recirculates to the heat transfer tube 18 is higher than the predetermined 12 ° C. as described above. The temperature T1 is also higher than the predetermined temperature of 7 ° C., and the cold water evaporator inlet side temperature T2 and the cold water evaporator outlet side temperature T1.
In addition, in the case of this example, the temperature gradually decreases while maintaining the temperature difference of 5 ° C.

The controller 22 also controls the rotational speed N of the cold water pump 19 so that the cold water evaporator inlet side temperature T2 becomes a constant temperature (12 ° C. in this case), but 50% of the rated value. Is set as the minimum flow rate so that the flow rate does not fall below this. Therefore, the rotation speed N is 50 which is the standard.
In the state of being fixed to%, the temperature T2 of the inlet side of the cold water and the opening degree V of the fuel control valve 2a are substantially proportional to each other as indicated by the one-dot chain line in FIG. Even when the cooling load rises when N exceeds 50%, the temperature T2 of the evaporator inlet side of the cold water is approximately 12 ° C except when the temperature T1 of the evaporator outlet side of the cold water is higher than 7 ° C. Maintained at.

That is, the evaporator inlet side temperature T2 of the chilled water that is supplied to the cooling load at a predetermined temperature of 7 ° C. and returns to the heat transfer tube 18 after finishing the cooling operation does not rise so much because the cooling load is small. Lower than ℃, 0-5 cooling load conversion
When it is in the range of 0%, the rotation speed N of the cold water pump 19 is fixed to the minimum rotation speed, for example, 50% of the rated value in this embodiment, and the flow rate of the cold water flowing through the cold water pipe 20 is minimized. A large reduction in energy can be achieved. Further, the amount of cold water flowing through the heat transfer tube 18 of the evaporator 5 can be secured, freezing in the evaporator 5 can be avoided, and the operation under partial load can be stabilized.

The temperature T2 at the inlet side of the evaporator is 12 ° C., where the cooling load is increased, the cooling action is finished, and the cold water flowing back to the heat transfer tube 18 is returned.
When the temperature is higher, the rotation speed N of the chilled water pump 19 increases, whereby the flow rate of the chilled water supplied to the cooling load increases, the evaporator inlet side temperature T2 of the chilled water decreases, and the temperature returns to 12 ° C.

Therefore, in the absorption refrigerating machine having the above-mentioned configuration including the control device of the present invention, the flow rate of the cold water flowing through the cold water pipe 20 and supplied to the cooling load is 0 when the cooling load is 0, as shown in FIG. When it is in the range of -50% (cold water evaporator inlet side temperature T2 conversion 7-12 ° C), the rotation speed N of the chilled water pump 19 is fixed to the minimum rotation speed and becomes the minimum, and the cooling load increases to 50%. When (cooling water evaporator inlet side temperature T2 conversion 12 ° C.) is exceeded, the rotation speed N of the cooling water pump 19 increases in proportion to the increase of the cooling load, whereby the flow rate of the cooling water supplied to the cooling load. Therefore, the evaporator inlet side temperature T2 of the chilled water that returns to the heat transfer tube 18 after finishing the cooling operation is approximately 12 ° C. in the cooling load range of 50 to 100%.

The control of the rotation speed N of the chilled water pump 19 by the controller 22 when the cooling load is in the range of 50 to 100% may be carried out by PID control based on the evaporator inlet side temperature, for example.

The temperature sensors 23 and 24 can also be installed inside the evaporator 5.

[0023]

As described above, the present invention has a heating amount control function for controlling the heating amount of the generator based on the evaporator outlet side temperature of the cold water taken out via the heat transfer tube inside the evaporator. A flow rate control function for controlling the flow rate of the cold water based on the evaporator inlet side temperature of the cold water that returns to the heat transfer tube after finishing the cooling action, and is a control device for an absorption refrigerator.

A heating amount control function of controlling the heating amount of the generator on the basis of the evaporator outlet side temperature of the cold water taken out through the heat transfer pipe inside the evaporator, and the cooling action is returned to the heat transfer pipe. When the temperature on the evaporator inlet side of the cold water is lower than a predetermined temperature, the flow rate of the cold water is decreased, and when the temperature on the evaporator inlet side of the cold water exceeds the predetermined temperature, based on the temperature on the evaporator inlet side. Since it is a control device for an absorption refrigerator having a control function for increasing the flow rate of the cold water and a control function for maintaining the flow rate of the cold water at a lower limit flow rate or more,

Since the heating amount of the generator is controlled on the basis of the temperature of the cold water on the evaporator outlet side and the flow rate of the cold water is controlled on the basis of the temperature of the cold water on the evaporator inlet side, the cold water on the evaporator inlet side is controlled. When the cooling load decreases when the temperature decreases,
The rotation speed of the cold water pump decreases so that the flow rate of cold water decreases. As a result, the power consumption can be significantly reduced, and the operation can be performed with high energy efficiency. In addition, the flow rate of cold water is maintained above the lower limit flow rate, and even when the cooling load is significantly reduced, cold water above the lower limit flow rate circulates in the evaporator,
Freezing of the evaporator can be avoided, and the absorption refrigerator can be operated stably.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a device configuration of an embodiment.

FIG. 2 is an explanatory diagram for controlling a heating amount in a high temperature regenerator.

FIG. 3 is an explanatory diagram in which a flow rate of cold water is viewed from a viewpoint of a cooling load.

FIG. 4 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

 1 High Temperature Regenerator 2 Combustion Device 3 Low Temperature Regenerator 4 Condenser 5 Evaporator 6 Refrigerant Distributor 7 Absorber 18 Heat Transfer Tube 19 Cold Water Pump 20 Cold Water Pipe 22 Controller 23/24 Temperature Sensor

Claims (2)

[Claims] 1. A heating amount control function for controlling the heating amount of a generator based on the evaporator outlet side temperature of cold water taken out via a heat transfer pipe inside the evaporator; And a flow rate control function of controlling the flow rate of the cold water based on the evaporator inlet side temperature of the cold water that recirculates. 2. A heating amount control function for controlling the heating amount of the generator based on the evaporator outlet side temperature of the cold water taken out via the heat transfer pipe inside the evaporator, and the heat transfer pipe after the cooling operation is completed. When the evaporator inlet side temperature of the circulating cold water is lower than a predetermined temperature, the flow rate of the cold water is reduced, and when the evaporator inlet side temperature of the cold water exceeds a predetermined temperature, the evaporator inlet side temperature is lowered. A control device for an absorption chiller, comprising: a control function for increasing the flow rate of cold water based on the above; and a control function for maintaining the flow rate of cold water at a lower limit flow rate or more.