JPS6132586B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for automatically operating an absorption refrigerator.

FIG. 1 shows a conventional steam-type double-effect absorption refrigerator, which uses water as a refrigerant, a lithium bromide solution as an absorbent, and steam as a heating source.

In the figure, 1 is a high pressure regenerator, 2 is a low pressure regenerator, 3 is a condenser, 4 is an evaporator, 5 is an absorber, 6 is a low temperature solution heat exchanger, 7 is a high temperature solution heat exchanger, and 8 to 14 are Solution piping, 15 is a regenerator pump, 16 is an absorber pump, 17 is an ejector, 18 to 20
21 is a refrigerant pipe, 21 is a refrigerant pump, 22 is a steam pipe, 23 is a cooling water pipe, 24 is a chilled water pipe, and 25 is a cooling water pump.The pipes are connected as shown in the figure, and the refrigerant evaporated in the high-pressure regenerator 1 is Low pressure regenerator 2
It enters the condenser 3 through heat exchange with the water in the cooling water pipe 23, condenses and liquefies, and then enters the evaporator 4, where it exchanges heat with the water in the cold water pipe 24 and evaporates. This cools the water in the cold water pipe 24. On the other hand, the evaporated refrigerant is absorbed by the solution in the absorber 5, and the solution whose concentration has become diluted by absorbing the refrigerant is passed through the low temperature solution heat exchanger 6 and the high temperature solution heat exchanger 7 to the high pressure regenerator 1 by the pump 15. Enter steam pipe 2
2, the refrigerant is evaporated and separated to form a highly concentrated solution, which enters the low pressure regenerator 2 via the high temperature solution heat exchanger 7, where it exchanges heat with the refrigerant, and then passes through the low temperature solution heat exchanger 6. After that, it is mixed with the solution from the absorber pump 16 in the ejector 17 and sprayed into the absorber 5.

One operation mode of such an absorption refrigerator is a dilution operation mode.

The purpose of this dilution operation is to prevent crystal precipitation when the engine is being operated under a certain load and the operation is terminated because the load has decreased. In other words, if auxiliary equipment such as the regenerator pump and refrigerant pump are immediately stopped and left unattended at the same time as the chiller stops operating, the temperature of the system will drop due to natural heat radiation, etc., and the low-temperature solution heat that was at a high concentration until just before the operation stopped will drop. Crystal precipitation occurs in the solution at the outlet of the exchanger. If crystal precipitation occurs, the pipes may become clogged during the next startup, or crystals may flow into the pump, damaging it and rendering it inoperable, so pumps should continue to operate even after refrigeration operation has stopped. The purpose of dilution operation is to reduce the concentration of high concentration solutions by mixing them with low concentration and medium concentration solutions contained in the system, thereby preventing crystal precipitation.

However, it is not known to what extent the solution is actually uniformly diluted by this dilution operation, so at present, a timer is used to ensure that the solution is sufficiently stirred for a specified period of time (approximately 30 minutes) even after the refrigerator has stopped operating.
Although the refrigerator is in dilution operation (about 1 minute), the refrigerator is not under any load during this time, so from the point of view of operating efficiency, the electric power used to drive the pump can be said to be wasted.

The present invention has been proposed in view of the above points, and detects the condensed refrigerant temperature or the pressure inside the regenerator, the regenerator outlet solution temperature, and the solution exchanger outlet solution temperature, and uses the detected values and the solution concentration curve. The feature is that the solution concentration or concentration margin up to crystal precipitation is calculated, and when the solution concentration or concentration margin reaches a specified value, the dilution operation is automatically terminated. It is an object of the present invention to provide an automatic operation method for an absorption refrigerator that can shorten dilution operation time due to machine operation stoppage and enable efficient and energy-saving operation.

As described above, the present invention detects the condensing refrigerant temperature or the regenerator internal pressure, the regenerator outlet solution temperature, and the solution heat exchanger outlet solution temperature, and calculates the solution concentration or crystal precipitation from the detected values and the solution concentration curve. ,
Since the concentration margin is calculated and the dilution operation is automatically terminated when the solution concentration or concentration margin reaches a specified value, crystal precipitation does not occur even due to natural heat radiation after the dilution operation is completed. Moreover, since the dilution operation time can be kept to the minimum necessary, there is no need to consume excess power, which saves energy.This is especially effective when starting and stopping a large number of times, and improves operating efficiency. be able to.

Hereinafter, the present invention will be explained based on illustrated embodiments.

FIG. 2 shows a configuration diagram of a steam-type double-effect absorption refrigerator in which the present invention is implemented, and 1 to 25 are the first
It is similar to the conventional one shown in the figure, and in addition to these, the condensed refrigerant temperature T ₁ and the low pressure regenerator outlet solution temperature
Temperature detectors 101, 102, 10 for detecting T ₂ and low temperature solution heat exchanger outlet solution temperature T ₃ respectively
3. Calculate the solution concentration and concentration margin up to crystal precipitation from the temperatures detected by the temperature detectors 101, 102, and 103, compare this concentration margin with a preset specified value, and determine whether the margin is the specified value. If it is smaller than the specified value, dilution operation, that is, operation of the regenerator pump 15, absorber pump 16, and cooling water pump 25, is continued, and if the value exceeds the specified value, the pumps 15, 1 are
A microcomputer 104 is provided which outputs a command to stop the operation of the motors 6 and 25.

Next, a method of operating the absorption refrigerator will be explained with reference to FIGS. 3 and 4.

The condensed refrigerant temperature T ₁ detected by the temperature detectors 101, 102, 103 when the refrigeration operation by the absorption refrigerator is stopped, and the low pressure regenerator outlet solution temperature
T ₂ and the low temperature solution heat exchanger outlet solution temperature T ₃ are input to the microcomputer 104, and the microcomputer 104 calculates the solution concentration X ₁ and the concentration margin ΔX until crystal precipitation. This solution concentration X ₁ is determined by the condensed refrigerant temperature T ₁ as shown in FIG.
The pressure inside the low-pressure regenerator calculated from the saturation characteristics of water and
It is calculated according to the lithium bromide solution concentration curve from P ₁ and the low pressure regenerator outlet solution temperature T ₂ , and the concentration margin △X until crystal precipitation is the low pressure solution heat exchanger outlet solution temperature in the solution crystal characteristics. temperature
Crystal precipitation concentration at T ₃ X ₂ and solution concentration determined earlier X ₁
This concentration margin △X is calculated by ^the difference △X = ^X _{1 -} If △X≧△X ^s , issue a command to terminate the dilution operation, and
6 and 25 are operated and stopped, and when the concentration margin △X finally reaches the specified value △Xs or ^more , the dilution operation is automatically terminated. Therefore, even with natural heat dissipation after the completion of the dilution operation, there is no need to worry about crystal precipitation, and the dilution operation time can be minimized, preventing power wastage due to safe operation. , it is possible to measure energy savings.

Note that in the above embodiment, the pressure P ₁ in the low pressure regenerator is calculated by detecting the condensed refrigerant temperature T ₁ ;
_The pressure P ₁ in the low pressure regenerator may be directly detected by a pressure detector.

Furthermore, the dilution operation is terminated when the concentration margin △X until crystal precipitation reaches the specified value △X ^s or _more , but the dilution operation may be determined based on the solution concentration If the solution temperature _T3 at the outlet of the solution heat exchanger does not fall below 40℃, the crystal precipitation limit is approximately _64.8 % from Figure 4, so if the solution concentration No precipitation occurs.

Furthermore, it goes without saying that a mini-computer or a large-sized computer can be used instead of the microcomputer, and that the present invention can also be applied to a single-effect absorption refrigerator.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing a conventional system, Fig. 2 is a block diagram showing an embodiment of the present invention, Fig. 3 is a system diagram explaining its operating method, and Fig. 4 is a lithium bromide solution concentration curve diagram. be. 15: Regenerator pump, 16: Absorber pump, 2
5: Cooling water pump, 101: Condensed refrigerant temperature detector, 102: Low pressure regenerator outlet solution temperature detector, 1
03: Low temperature solution heat exchanger outlet solution temperature detector, 1
04: Microcomputer.

Claims (1)

[Claims] 1. Detect the condensed refrigerant temperature or the regenerator internal pressure, the regenerator outlet solution temperature, and the solution heat exchanger outlet solution temperature, calculate the solution concentration or the concentration margin until crystal precipitation from the detected values and the solution concentration curve, An automatic operation method for an absorption refrigerator, characterized in that the dilution operation is automatically terminated when the solution concentration or concentration margin reaches a specified value.