JPS58883B2 - Air or gas dehumidification method - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for dehumidifying air or gas.

In conventional dehumidification methods, one of the two heat exchangers is maintained at a temperature above the freezing point and the other at a temperature below the freezing point.
Dehumidification is performed by switching operation so that the first inlet for air or gas is always on the side of the heat exchanger whose temperature is above the freezing point.

(Japanese Patent Publication No. 52-48751, Japanese Patent Publication No. 54-635
(No. 40) However, these conventional methods have various problems as described later.

The invention was made in order to solve the problems of the conventional method, and the refrigerant is made to flow through two or more heat exchangers, respectively, so that the heat exchangers are heated to a temperature lower than the freezing point and different from each other. The air or gas is first introduced into a "higher temperature" heat exchanger to allow ice formation to take place and the resulting pore moisture is removed, and then the air or gas is
When the amount of frost exceeds a predetermined value, the heat exchanger is introduced into a heat exchanger with a lower temperature to form frost. Higher low temperature”
On the other hand, the heat exchanger with the "higher low temperature" that caused the ice formation to be switched to the "lower temperature" than 1, and the heat exchanger with the temperature switch in this way corresponds to this. This is an air or gas dehumidification method in which the order of introducing air or gas into the container is reversed to perform the same "icing formation, water removal, and frost formation" as described above, and the dehumidification capacity is extremely large. Moreover, the purpose is to enable efficient operation.

In conventional dehumidification methods, when a refrigerator is generally used, one heat exchanger has a dew point of 0°C or higher, as described above, to improve heat transfer and prevent frost from forming on the coil. It dehumidifies moisture in the form of droplets.

Therefore, when lowering the dew point to around -40℃,
The two heat exchangers are alternately switched to a temperature above 0°C and a temperature before -40°C and maintained. When the temperature is above 0°C, dehumidification is performed with droplets, and when the temperature is before -40°C, frost is formed on the coil. However, when operating with a single refrigerator, if the temperature difference between the two heat exchangers becomes large, the evaporation temperature on the heat exchanger side is kept high to maintain the temperature above 0℃. Therefore, it is necessary to restrict the flow of refrigerant using an evaporation pressure regulating valve (EPR), etc. (because the temperature on the low-temperature heat exchanger side is the standard), and therefore the suction capacity of the refrigerator is different from the 0°C temperature and the reference temperature. The larger the temperature difference, the more loss will occur.

On the other hand, in order to reduce the loss of suction capacity of the refrigerator, it is sufficient to keep the temperature difference mentioned above small, but in order to obtain an extremely low dehumidification dew point, it is necessary to lower the dew point of one side. As a result, it is necessary to maintain a large temperature difference between 0°C or higher and a lower temperature.

For this reason, in the conventional method, for example, one side of the heat exchanger is heated to 0°C.
If the other temperature is set at around -30°C, the pressure regulating valve on the 0°C side throttles down -30°C, so the temperature difference is Δt30°.

Therefore, in this case, the minimum dehumidification dew point is -30°C.

On the other hand, in the present invention, in the case of single-stage compression, if one of the heat exchangers is set to around 115°C and the other is set to around 130°C, the temperature difference can be Δt15°.

In addition, in the case of two-stage compression in the present invention, if one of the heat exchangers is set to about 115°C and the other is set to about 140°C, then if the intermediate temperature of the two-stage compression is 115°C, Since the temperature difference between the intermediate temperature and 15° C. on one side of the heat exchanger is ΔtO°, the pressure loss of the EPR is almost 0.

On the other hand, in the conventional method, since one side of the heat exchanger is at 0° C., the temperature difference from the intermediate temperature is Δt15°, and the pressure loss of the EPR is not avoided.

Moreover, according to the method of the present invention, it is possible to obtain a dew point of -40° C., which cannot be obtained using conventional methods.

Furthermore, in the conventional method, the frosted surface of the cooler in the heat exchanger has a poor heat transfer rate, which reduces the dehumidifying ability, but in the present invention, a frozen layer is formed on the surface of the cooler in the heat exchanger instead of a frosted layer. Because of this, the heat transfer coefficient is higher than that of the frosted layer, and the formation of the frozen layer increases the heat transfer surface area, which increases the overall heat exchange effect and maintains a high dehumidification capacity. It is.

Next, an embodiment of the present invention will be described with reference to FIG.

In FIG. 1, Ia and lb are heat exchangers, and the partition wall 2
, and communicated through a communication path 3.

Each heat exchanger 1a, 1b has an air or gas inlet 4a,
4b and dry air or dry gas outlet ports 5a, 5b are formed, and the inlet ports 4a, 4b and the outlet ports 5a, 5b are connected to the primary heat exchanger 7 and this primary heat exchanger via switching valves 5a, 5b, respectively. 7 is connected to the coil 8 through a hole.

Further, the lower bottoms of the respective heat exchangers 1a and Ib are communicated with a common water droplet groove 9.

Furthermore, a cooler 10a is provided in each of the heat exchangers 1a and Ib.
, 10b are inserted.

The refrigeration cycle into which the coolers 10a and 10b are inserted has the following configuration.

Gas return pipes 17a and 17b using one single-stage compressor 11
An evaporation pressure adjustment valve 34a is located in the middle of the evaporation pressure adjustment valve 34a.

34b is provided.

This evaporation pressure regulating valve is an external pressure equalization type.

35a, 35b are bypasses, and solenoid valves 36a, 36
When b is closed (OFF), evaporation pressure regulating valve 3
4a, 34b maintain a constant regulated temperature formed by pilot valves 37a, 37b, and solenoid valves 36a, 36b are open (O
N), the evaporation pressure regulating valves 34a and 34b
is fully opened, there is no differential pressure in the suction pressure, and the temperature becomes the lowest negative temperature of the suction low pressure temperature of the refrigerator 11.

When the solenoid valves 36a and 36b are closed, the pilot valve 37a,
37b acts as the evaporation pressure regulating valve 34a.

34b is operated while maintaining a specified required pressure difference.

Although the temperature at this time is negative, there is a pressure difference such that there is a temperature difference with the temperature corresponding to the compressor suction pressure, and the compressor operates at a temperature higher than the suction evaporation temperature.

The discharge gas pipe 12 led out from the single-stage compressor 11 is connected to the condenser 13, and the liquid pipes 15a and 15b led out from the liquid receiver 14 and branched are provided with expansion valves 16a and 1, respectively, in the middle.
cooler 10a via 6b.

iob and gas return pipes 17a, 17b led out from the coolers 10a, 10b are connected to a common suction gas pipe 19.

38a and 38b are solenoid valves.

Next, the air compressor 27, aftercooler 28, and air tank 29 are connected to the air or gas introduction side in sequence, and the air introduction pipe 30 led out from the air cylinder 29 is connected to the primary heat exchanger 7. Humid air pipe 31 led out from 7
is connected to one switching valve 6a, and the dry air pipe 32 led out from the other switching valve 6b is connected to the coil 8 in the primary heat exchanger 7.
is communicated with the dry air outlet pipe 33.

In this embodiment, the coolers 10a, 10b act as refrigerant evaporators.

Next, a dehumidification method using the apparatus of this embodiment will be explained.

Air is compressed by an air compressor 27, and the high-temperature air containing moisture passes through an aftercooler 28 and an air pump 29 and enters the primary heat exchanger 7, where it is precooled by the cooled dry air and the heat exchanger.

Now, assuming that the switching valves 5a and 5b are in the position indicated by the solid line, the pre-compressed and pre-cooled air or gas is first introduced into the first heat exchanger 1a through the inlet 4a, and then cooled to -40°C by the cooler 10a. Moisture in the air or gas is cooled and forms frost on its surface.

The air or gas is then introduced into the second heat exchanger 1b,
Here, too, it is cooled by the -40° C. cooler 10b and further frosting is performed.

The first heat exchanger 1a into which air or gas is introduced first has a faster rate of frosting, and when the amount of frosting reaches a predetermined value, the pressure difference between the air or gas introduction side and outlet side is detected. The pressure switch 20a operates, the solenoid valve 36a closes, and the pilot valve 37a operates to adjust the opening degree of the evaporation pressure regulating valve 34a, so that the temperature of the cooler 10a is adjusted to -15°C.

Thereafter, steady operation will be performed by switching.

That is, air or gas is subsequently introduced into the first heat exchanger 1a, but since the temperature of the air or gas is high, the upper layer of frost that has adhered at -40°C is melted as described above. A part of the melted water is removed to the water droplet groove 9, and the other water enters into the frosted layer on the surface of the cooler 10a, and the whole becomes frozen. .

In this process, some of the moisture in the air or gas is removed as water droplets and flows into the water droplet groove 9.

Since the frozen surface of the cooler 10a is in contact with high temperature air, it is always kept wet.

Due to this ice formation, the surface diameter of the coil of the cooler 10a becomes larger than that in the case where no ice is deposited, and the surface area also becomes larger.

The heat transfer coefficient of ice is better than that of frost, and although it is inferior to that of a bare pipe surface, the increased surface area due to ice formation compensates for this.

The air or gas that has been changed from a frosted state to a frozen state and from which moisture has been removed in the first heat exchanger 1a is then transferred to the second heat exchanger 1b.
The coil is further cooled by contacting the -40°C cooler 10b, and moisture forms frost on the surface of the coil, and the amount of frost gradually increases.

When the amount of frost reaches a predetermined value, the pressure switch 20b is activated by detecting the flow resistance of air or gas, and the solenoid valve 36b is activated.
is closed and the pilot valve 37b operates and the evaporation pressure regulating valve 3
By adjusting the opening degree of the cooler 10b, the temperature of the cooler 10b is adjusted to -15°C.

On the other hand, in the first heat exchanger 1a, as the coil surface of the cooler 10a changes from a frosted state to a frozen state as described above, the flow resistance of air or gas is reduced, and the pressure switch 20a
is activated, the solenoid valve 36a is opened, the pilot valve 37a is deactivated, and the evaporation pressure regulating valve 34a is fully opened, so that the temperature of the cooler 10a is switched to -40°C.

At this time, the switching valve 5a on the air or gas introduction side.

6b and first introduce air or gas into the second heat exchanger 1b from the inlet 4b.

The high-temperature air or gas heats the frosted surface of the coil of the cooler IQb, melting the upper layer of frost that has adhered when the temperature is -40°C, and some of the melted moisture forms a frosted state on the surface of the cooler 10b. It penetrates into the frozen layer and transforms the frosted layer into a frozen layer.

The other portion of the dissolved water is removed and flows into the water droplet groove 9.

Due to this ice formation, the surface area of the coil of the cooler 10b becomes larger than that without ice, and as in the case where ice forms on the coil surface of the cooler 10a described above, the heat transfer coefficient and surface area of the ice become larger than that of the bare pipe surface. It can exhibit comparable heat exchange effect.

The air or gas cooled by the second heat exchanger 1b then flows into the first heat exchanger ia and touches the frozen surface of the cooler 10a at a temperature of -40°C, causing the moisture in the air or gas to freeze. It sticks to the surface in a box shape and is removed.

When the amount of frost exceeds a predetermined value, the pressure switch 20a is activated and the temperature of the cooler 10a is changed to about -15°C.

In Fig. 2, the compressor 11 is a so-called two-stage compressor, consisting of a high-stage side 11a and a low-stage side 11b, each having a different capacity. A discharge gas pipe 12 connects the low stage side 11b and the high stage side 11a in series.
a is connected to the condenser 13.

Gas return pipe 17a led out from coolers 10a, 10b
, 17b are communicated with the four-way switching valve 18.

This four-way switching valve 18 is an electric valve and the gas return pipes 17a, 17
b is alternately connected to the suction gas pipe 19a on the high stage side 11a and the suction gas pipe 19b on the low stage side 11b, and for this switching operation, the four-way switching valve 18 is connected to the heat exchanger 1a.
, pressure switches 20a and 20b which operate by detecting the pressure difference between the gas inlet side and the gas outlet side in Ib, and the differential pressure regulator 53.
This is done by connecting via .

Since it is a two-stage compression device, the temperature of the evaporator is 15℃.
The temperature is EPR with a lower intake temperature of around -40℃.
Since the EPR is inserted on the intake side at an intermediate temperature instead of being set at -15°C, the temperature difference will be reduced.

The rest of the structure is the same as the embodiment shown in FIG. 1, and the dehumidification operation is also performed in the same manner as in FIG.

In FIG. 2, the low stage side 11b and the high stage side 11a are connected in series, but as shown in FIG. 3, the low stage side 11b and the high stage side 11a are connected in parallel, that is, the discharge gas pipe of the low stage side 11b Even when both the discharge gas pipe 12b and the discharge gas pipe 12a of the high stage side 11a are connected to the condenser 13, the cooler on the heat exchanger side, which is set to a temperature of -15°C or lower, is always connected to the high stage side 11a of the compressor. Since the EPR is connected to the EPR, there is almost no pressure loss.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a first embodiment for implementing the uninvented method, FIG. 2 is an explanatory diagram of the second embodiment, and FIG. 3 is an explanatory diagram of a part of the third embodiment. . ia, ib...heat exchanger, 4a, 4b...
...Air or gas inlet, 5a, 5b... Air or gas outlet, 10a, 10b... Cooler.

Claims (1)

[Claims] 1 A refrigerant is passed through each hole of two or more heat exchangers, each of which is maintained at a low temperature below the freezing point and different from the other, and the air or gas is first heated at a higher low temperature. The air or gas is introduced into an exchanger to form ice and remove the resulting moisture, and then the air or gas is introduced into a lower temperature heat exchanger to form frost, and the amount of frost is exceeds a predetermined value, the heat exchanger with a lower temperature that caused frost formation to become a higher low temperature, while the heat exchanger that caused ice formation to occur with a higher temperature become lower. The temperature is changed to a lower temperature, and the order of introduction of air or gas into the heat exchanger whose temperature has been changed in this way is also reversed, and ice formation, water removal, and the like described above are performed. A method of dehumidifying air or gas that causes frost formation.