JP3203039B2 - Absorption refrigerator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art First, the structure of this type of absorption refrigerator will be described with reference to FIG. 3. Reference numeral 1 denotes a load pipe for circulating cold water to an indoor cooling unit or the like, and 2 denotes a cooling water pipe for introducing cooling water from an outdoor cooling tower or the like. Yes, the refrigerant vapor (steam) generated in the high-temperature regenerator 4 by the heating of the burner 3 and the medium concentration solution of the absorbent (lithium salts) are separated in the separator 5,
The refrigerant vapor passes through the heating tube of the low-temperature regenerator 6 to heat the solution, and is cooled together with the refrigerant vapor released from the solution in the condenser 7 to return to the refrigerant liquid (water). The sprayed water cools the cold water in the load circuit 1 and evaporates itself, and is cooled by the absorber 9 and absorbed by the solution. On the other hand, the medium-concentration solution is sent from the separator 5 to the low-temperature regenerator 6 through the high-temperature heat exchanger 10, is concentrated to a high concentration by heating with the refrigerant vapor, and is further absorbed through the low-temperature heat exchanger 11. Sent to the evaporator 9 to absorb the refrigerant vapor from the evaporator 8 to become a dilute solution. The diluted solution is pressure-fed to the high-temperature regenerator 4 by the solution pump 12 while being heated by the low-temperature heat exchanger 11 and the high-temperature heat exchanger 10.

FIG. 4 shows the operating characteristics of the absorption refrigerator. The symbols 〜 indicate the temperature, pressure and concentration of the solution at the same reference numerals in FIG.
And → indicate a low temperature heat exchanger 11 of a dilute solution (about 62%).
And the temperature rise in the high-temperature heat exchanger 10, → is heating by the high-temperature regenerator 4, → is concentration by the high-temperature regenerator 4, → is the high-temperature heat exchanger 1 of a medium concentration solution (about 60%).
Temperature drop at 0, → is concentration by low-temperature regenerator 6, → is low-temperature heat exchanger 1 of high concentration solution (about 58%)
1, represents the cooling by the cooling water in the absorber 9, and → represents the absorption of the refrigerant in the absorber 9.

[0004] The cooling water inlet temperature during normal operation is about 32
° C, the outlet temperature is about 39 ° C, and the inlet temperature is maintained by controlling the number of revolutions of the cooling fan. When the cooling water temperature falls, the solution temperature in the absorber falls from Ta to Tb along the broken line in FIG.
From 1 to P2, the evaporation temperature of the evaporator also drops from T1 to T2, and therefore, there is a danger of freezing of the refrigerant at the surface of the cold water pipe or the vicinity of the refrigerant spray port where the temperature drops most. Therefore, as shown in FIG.
3 and a valve 14 to release the stored refrigerant at the end of the operation to increase the amount of refrigerant (water) in the entire system in preparation for the start of the operation in which the cooling water temperature drops to the outside temperature. The solution is squeezed to return the concentration of the solution to normal. This is equivalent to translating the absorption cycle curve to the left (indicated by the dashed line in FIG. 4), so that even if the solution temperature drops from Ta to Tb, the vapor pressure and the evaporation temperature respectively Freezing can be prevented without changing P1 and T1.

In early summer or the like, the temperature of the cooling water may become lower than a set value during operation when the temperature is low. Conventionally, as a measure for preventing freezing in such a case, as shown in FIG. 3, a temperature sensor 15 for monitoring the refrigerant evaporation temperature of the evaporator 8 is provided.
When the refrigerant evaporation temperature falls below a certain value, the opening of the valve 14 is increased to discharge the refrigerant liquid from the refrigerant storage chamber 13.

[0006]

As described above, when the temperature sensor 15 detects that the temperature of the evaporator 8 has dropped, the valve 14 is opened, and the refrigerant liquid is discharged to prevent crystallization of the solution. The absorption cycle curve shifts to the left as a whole, and the refrigeration capacity decreases accordingly. Therefore, it is desirable to return the solution concentration as soon as possible after the cooling water temperature returns to normal.
However, in the above-described conventional configuration, after the temperature of the cooling water has decreased, the temperature of the solution has decreased, and the vapor pressure in the evaporator 8 has decreased, whereby the evaporation temperature of the refrigerant has decreased. Since it takes a long time to detect, even after the cooling water temperature returns to normal, it takes a considerable time until the valve 14 returns and the cooling capacity returns to normal, and during that time, the normal cooling operation is performed. There was a problem that it was not possible.

[0007]

According to the present invention, as shown in FIG. 1, a refrigerant storage chamber 13 for temporarily storing a refrigerant liquid in a refrigerant path from a condenser 7 to an evaporator 8 is provided. Valve 14 for controlling the flow rate of the refrigerant liquid flowing out of the chamber 13
And a water level sensor 16 in the refrigerant storage chamber 13,
A cooling water temperature sensor 17 is provided at each cooling water inlet, and the valve 14 is controlled so that the current water level approaches a target water level determined by the cooling water temperature.

[0008]

The first problem in controlling the valve using the cooling water temperature is that load fluctuation cannot be detected, but the vapor pressure in the evaporator is determined only by the concentration and temperature of the solution. This also determines the evaporation temperature of the cold water pipe surface. Therefore, even if the load fluctuates and the temperature of the cold water pipe decreases, the amount of evaporation decreases and the cooling function is suppressed, so that the fluctuation of the load can be ignored. If the temperature of the cooling water drops, it is possible to prevent the cooling capacity from dropping when the temperature rises again, if the required minimum dilution can be used. It is necessary to stop the discharge of the refrigerant liquid when the required amount is reached. The water level sensor in the present invention fulfills its role.

[0009]

FIG. 1 shows an embodiment of the present invention. The difference from the conventional example of FIG. 3 is that the temperature sensor 15 is eliminated and a cooling water temperature sensor 17 is provided at a cooling water inlet.
A water level sensor 16 is provided in the refrigerant storage chamber 13, and a valve 14 is provided so that the current water level approaches a target water level determined by the cooling water temperature.
Is controlled, and the other structure is as described with reference to FIG. As the valve 14, a proportional valve capable of adjusting the opening degree in three or more stages is used. However, an on / off valve may be used to change the duty ratio. The water level sensor 16 can be easily configured by, for example, dividing the water level into 7 to 8 stages and detecting the position of the float using the same number of proximity switches or photoelectric switches.

FIG. 2 is a flowchart showing the operation of the valve control device. First, the cooling water temperature is measured, the target water level is obtained by an arithmetic expression or a calibration table, and then the current water level is measured and the target water level is measured. Compare with the water level, and if there is a difference, adjust the flow rate by changing the valve opening so that the current water level approaches the target water level. In this case, when the difference between the target water level and the current water level is two or more steps of the water level sensor, the responsiveness is further improved if the opening degree of the valve is changed by two or more steps.

[0011]

According to the present invention, as described above, the target storage chamber water level is immediately obtained from the current cooling water temperature and the current solution concentration (storage chamber water level) to control the valve opening. For example, it is much more responsive than the conventional method that can respond to a change in cooling water temperature for the first time by a change in the temperature of the cooling water detected after a few minutes, so that the generation of freezing can be reliably prevented, and the solution There is an advantage that the cooling capacity is not reduced due to excessive thinning.

[Brief description of the drawings]

FIG. 1 is a system diagram of one embodiment of the present invention.

FIG. 2 is an operation explanatory view of the above.

FIG. 3 is a system diagram of a conventional example.

FIG. 4 is an operation characteristic diagram of the above.

[Description of Signs] 1 Load piping 2 Cooling water piping 3 Burner 4 High temperature regenerator 5 Separator 6 Low temperature regenerator 7 Condenser 8 Evaporator 9 Absorber 13 Refrigerant storage room 14 Valve 16 Water level sensor 17 Cooling water temperature sensor

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hideki Tani 4-1-2, Hirano-cho, Chuo-ku, Osaka City Inside Osaka Gas Co., Ltd. (72) Inventor Toshihiro Ishibashi 941-16 Umeda, Kosai-shi, Shizuoka (72) Inventor Satoshi Naito 4494-24 Shinsho, Kosai-shi, Shizuoka (56) References JP-A-3-211371 (JP, A) JP-A-62-138663 (JP, A) JP-A-57-87573 (JP, A) JP-A-59-60162 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F25B 15/00 306

Claims (1)

(57) [Claims] 1. An absorption refrigerator including a regenerator, a condenser, an evaporator and an absorber, a refrigerant storage chamber for temporarily storing a refrigerant liquid in a refrigerant path from the condenser to the evaporator, A valve is provided to control the flow rate of the refrigerant liquid flowing out of the storage chamber, a water level sensor is provided in the refrigerant storage chamber, and a cooling water temperature sensor is provided at the cooling water inlet, so that the current water level approaches a target water level determined by the cooling water temperature. Absorption chiller characterized by controlling the temperature of the chiller.