JPS6115987B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an absorption cooling device and is directed to improving the efficiency of the system.

Conventionally, generators for absorption cooling systems that use relatively high-pressure refrigerants, such as ammonia or fluorocarbons,
A so-called flooded generator was used in which a concentrated solution was stored in a tank and heated to generate refrigerant vapor. In addition to this method of heating a concentrated solution to generate refrigerant vapor, there is also a method of heating the concentrated solution by forcing the liquid to flow into the heating section using a pump, then evaporating the refrigerant. There is a so-called once-through type generator that separates refrigerant vapor and a liquid in which the refrigerant is diluted (hereinafter referred to as diluted solution). Compared to flooded type generators, once-through type generators (1) have a higher heat transfer coefficient, (2) when using combustion gas as the heat source, can have a considerably larger heat transfer surface on the combustion gas side. Although it has many advantages such as 3) good start-up characteristics due to its small heat capacity, and (4) low cost because it is easy to manufacture, it has hardly been used until now. One of the reasons for this is the problem of decreased efficiency. In the case of a flooded type, the solution is stored in a tank and then heated, so it is easy to bring the evaporated refrigerant vapor and the concentrated solution into contact with each other facing each other. Equilibrium is reached and the purity increases, and at the same time, the amount of heat input due to heating is reduced because the solution gives its own sensible heat to the concentrated solution, improving the efficiency of the cooling device. However, in the case of the once-through type, since the concentrated solution is forcibly circulated to the heating section by a pump, it is almost impossible to bring the refrigerant vapor and the relatively low temperature concentrated solution into contact with each other facing each other. Therefore, in devices that require rectification, such as absorption refrigerators that use ammonia and water, it is necessary to increase the amount of refrigerant refluxed from the condenser for rectification by the amount of refrigerant vapor that is low in purity. , resulting in a significant decrease in efficiency. Furthermore, even in systems where the boiling point difference between the refrigerant and the solvent is large and rectification is not that important, the amount of heat that refrigerant vapor throws away to the outside in the condenser increases, which not only reduces the efficiency of the equipment but also reduces the size of the condenser. becomes larger.

FIG. 1 shows an example of an absorption type cooling device having a once-through type generator and using gas combustion as a heat source, in which the present invention is not used. This device will be explained with reference to figures. The concentrated solution sent by the pump 8 exchanges heat with the high temperature dilute solution in the heat exchanger 9, and then enters the finch tube 2. Here, the concentrated solution receives heat from the gas burned in the burner 4, evaporates the refrigerant inside itself, and is diluted. A two-phase fluid containing a mixture of refrigerant vapor and dilute solution enters the container 3 and is separated into refrigerant vapor and solution, with the refrigerant vapor flowing out from the top and the dilute solution flowing out from the bottom. Such a container is called a gas-liquid separator because it separates into a gas phase and a liquid phase, and the refrigerant vapor enters the condenser 5 where heat is removed and condensed. The condensed liquid refrigerant then takes heat from the outside air in the evaporator 6, evaporates, and enters the absorber 7 in a gaseous state. On the other hand, the dilute solution separated from the refrigerant vapor in the partial liquid separator 3 gives heat to the concentrated solution in the heat exchanger 9 and enters the absorber 7. In this absorber 7, the refrigerant vapor that has flowed in from the evaporator 6 and the dilute solution are mixed, and the heat generated at the time is discarded to the outside to be regenerated as a concentrated solution, which is then circulated by the pump 8.

In such a device, the refrigerant vapor discharged from the gas-liquid separator 3 and sent to the condenser 5 reaches equilibrium with the dilute solution that has reached the maximum temperature in the liquid state inside the gas-liquid separator 3, and the temperature increases. Not only is it high, but if the difference in boiling point between the refrigerant and the solvent is small, the purity of the refrigerant is low. In such a case, it is necessary to attach a rectifier to the upper part of the gas-liquid separator to reflux the refrigerant from the condenser 5, but as mentioned above, the reflux ratio is higher than in the case of a flooded type, which reduces the efficiency of the cooling system. decreases.

The present invention improves the problems of the above-mentioned once-through type generator,
This is intended to improve the efficiency of absorption cooling equipment.

The details of the present invention will be explained below with reference to the drawings. FIG. 2 shows an embodiment according to the present invention. 1st
The difference from the figure is that the heat exchanger 19 is branched from the pipe line of the finch tube 12, and a branch pipe line 10 is provided. This branch line 10 may branch from any part between the pump 18 and the finch tube 12. A part of the concentrated solution sent from the pump 18 through this branch line 10 is sent directly to the gas-liquid separator 13 without being heated by combustion gas.
The high-temperature refrigerant vapor separated by the gas-liquid separator 13 faces and contacts the concentrated solution sent through the branch pipe 10, reaches equilibrium with the concentrated solution, becomes relatively low-temperature refrigerant vapor, and is sent to the condenser 15. It is discharged. Condenser 15
The refrigerant is evaporated in the evaporator 16 and guided to the absorber 17. In other words, the sensible heat of the high-temperature refrigerant vapor is recovered into the branched concentrated solution, and the efficiency is improved by the amount recovered. In addition, since the refrigerant vapor comes into contact with a highly concentrated solution at a relatively low temperature, the purity of the refrigerant vapor itself increases.
This aspect also leads to improved efficiency. Improving refrigerant purity contributes to lowering the refrigerant reflux ratio even in systems that require rectification, so the efficiency of the apparatus improves as in the system that does not require rectification as described in the example here.

FIGS. 3 and 4 show the effects of the embodiment of the present invention confirmed through experiments. FIG. 3 shows the efficiency of the cooling device with respect to the temperature of the dilute solution in the gas-liquid separator. The zero branch flow rate curve shows the efficiency without implementing the invention. Further, the branching flow rates of 0.2 and 0.5 are obtained by branching a concentrated solution according to the present invention and changing the amount of liquid to be branched. According to this figure, the effect of branching the concentrated solution is clearly seen, and the efficiency of the cooling device is improved.

Figure 4 shows how much the refrigerant vapor temperature discharged to the condenser falls with respect to the branch flow rate. As the temperature drop increases, the amount of heat recovered increases and Unnecessary burden on the equipment will be reduced.

As described above, in the present invention, even if the generator is a once-through type, a remarkable effect is expected in improving the heat recovery and purity of the refrigerant vapor discharged from the generator, and as a result, the efficiency of the absorption type cooling device is improved.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a conventional absorption type cooling device having a once-through generator, Fig. 2 is a block diagram of an absorption type cooling device according to an embodiment of the present invention, and Fig. 3 is a block diagram of the cooling device efficiency due to changes in branch flow rate. Characteristic diagram showing changes in , 4th
The figure is a characteristic diagram showing changes in temperature drop of discharged refrigerant vapor due to changes in branch flow rate. 1, 11... Once-through generator, 2, 12... Finch tube, 3, 13... Gas-liquid separator, 10...
Concentrated solution branch tube.

Claims (1)

[Claims] 1. In an absorption cooling system comprising at least a generator, an absorber, a condenser, an evaporator, and a pump connected, the generator is connected to a single or multiple parallel pipes heated from the outside and their outlet ends. Most of the solution with high refrigerant concentration (hereinafter referred to as the concentrated solution) sent by the pump flows through the pipe, and the remaining concentrated solution does not flow through the pipe. An absorption type cooling device characterized by a heat exchanger with high-temperature refrigerant vapor that is diverted to a container, passes through the container, and is discharged to the condenser.