JPH0760028B2 - Refrigerator control device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a refrigerating apparatus using a mixed refrigerant.

2. Description of the Related Art A refrigeration system using a mixed refrigerant can perform capacity control and performance improvement by varying the composition ratio of the refrigerant circulating inside the cycle.

Conventionally, a rectification separation method utilizing a difference in boiling point has been used as a method for varying the refrigerant composition circulating in the cycle of a refrigerant device using a non-azeotropic mixed refrigerant (for example, Japanese Patent Laid-Open No. 61- No. 101757).

An example of the refrigerating apparatus using the rectification separation system will be described below with reference to FIGS. 7 and 8.

FIG. 7 is a refrigeration cycle diagram showing a conventional example, and FIG. 8 is a sectional view of a rectification column for changing the composition ratio of the non-azeotropic mixed refrigerant.

In FIG. 7, 1 is a compressor, 2 is a condenser, 3 is a main expansion device, and 4 is an evaporator, which are annularly connected to each other to form a main circuit. On the other hand, the outlet of the condenser 2 and the inlet of the rectification tower 6 are piped.
The heater 5 is connected to the pipe 10 by heat exchange. Further, the lower outlet of the rectification column 6 and the inlet of the evaporator 4 of the main circuit are connected via the auxiliary expansion device 7 by the pipes 11 and 12. Further, a cooler 8 and a reservoir 9 are provided above the rectification column 6, and the reservoir 9 is connected to the rectification column 6 in an annular shape by pipes 13 and 14. Also, cooler 8 and piping
13 and 13 are connected by heat exchange. Here, as the heat source of the heater 5 and the cooler 8, the discharge gas and the suction gas of the compressor 1 are used. As the refrigerant, a non-azeotropic mixed refrigerant composed of two kinds of refrigerants having different boiling points is used.

In FIG. 8, 601 is the main body of the rectification tower 6, 602 is a packing material,
603 and 604 are filler holders.

The operation of the refrigerating apparatus configured as described above will be described below.

First, the case where rectification separation is not performed will be described.

A part of the high-pressure liquid refrigerant discharged from the condenser 2 is branched by the pipe 10. At this time, if the valve opening of the sub-throttle device 7 is increased, the flow rate of the branch refrigerant branched to the pipe 10 is increased, the heating of the heater 5 is insufficient, evaporation does not occur, and the liquid is introduced from the lower inlet of the rectification column 6. Refrigerant flows in. As a result, the rectification action does not proceed, and the liquid refrigerant rises inside the rectification tower 6, enters the reservoir 9 through the pipe 13, and returns to the rectification tower 6 through the pipe 14. Then, the pressure is reduced by the sub expansion device 7 and merges with the main circuit side refrigerant.

In this way, the composition ratio of the low boiling point component inside the reservoir 9 does not rise, so that the composition ratio of the main circuit becomes equal to the refrigerant charging ratio.

Next, the case of performing rectification separation will be described.

When the valve opening of the sub-throttle device 7 is reduced from the above state, the flow rate of the branched refrigerant decreases, and the liquid refrigerant branched from the condenser 2 is heated by the heater 5 and partially vaporized. It flows in from the lower entrance of the distillation column 6. This gas component rises in the clearance of the packing material 602 in the rectification column 6, enters the cooler 8 through the pipe 13 from the upper outlet, is cooled and liquefied, and enters the reservoir 9.
The drop A between the reservoir 9 and the return pipe 14 of the rectification tower 6 is preset.
A part of the liquid refrigerant from the reservoir 9 is returned to the rectification column 6 again through the pipe 14 due to the drop A, and the packing material 602 is provided.
The rectifying column stores the refrigerant having a large amount of low boiling point components in the reservoir 9 by making a rectifying action by heat exchange and mass transfer by making a vapor-liquid contact with the vapor that rises halfway through the gap. From the lower part of 6, the refrigerant with a low low boiling point component is pipe 11,
It flows into the main circuit through the auxiliary expansion device 7 and the pipe 12.

Therefore, the low boiling point component ratio of the main circuit decreases and the high boiling point component ratio increases.

As described above, by controlling the valve opening of the sub expansion device 7, the amount of steam generated is adjusted for rectification separation, and the composition ratio of the refrigerant stored in the reservoir 9 is changed.
The composition ratio of the main circuit refrigerant can be made variable.

Problems to be Solved by the Invention However, the above configuration has the following problems.

First of all, in order to carry out rectification separation, it is necessary to perform heating, etc., and to inject the refrigerant vapor from the lower part of the rectification tower, but since the high-temperature discharge refrigerant is used for the heater, the temperature at the inlet of the condenser is increased during heating operation. Is reduced, the heating capacity is reduced.

Secondly, if the compressor is stopped after the rectification separation such as thermo-off, the main circuit and the separation circuit will be in compression balance, and the refrigerant concentration in the circuit will return to the initial refrigerant inclusion composition ratio.

In view of the above problems, it is an object of the present invention to realize a separation circuit that maintains a constant refrigerant concentration in the main circuit after completion of refrigerant separation, has less heat loss, and has good separation performance.

Means for Solving the Problems In order to solve the above problems, the present invention uses an electric heating heater as a heater, provides a two-way valve at the inlet of the rectification column, and can be fully closed at the outlet of the rectification column. A sub-throttle device is provided, and the temperature detection means for detecting the upper temperature of the rectification column and converting it to an electric signal and the electric signal output from the temperature detection means are input, the rate of change with time is calculated, and the electric signal is output. Calculating means, comparing means for comparing and judging the electric signal output from the calculating means and the set electric signal and outputting a control signal, energization of the electric heating heater, and the auxiliary throttle device and the two-way valve. A storage unit that stores an output mode for controlling opening and closing, a selection unit that selects one of the output modes of the storage unit by a control signal output from the comparison unit, and the electric heating according to the output mode of the storage unit. Through the heater Electricity
The sub-throttle device and the output means for controlling the opening / closing of the two-way valve.

Action The present invention has the above-described configuration, and detects completion of the refrigerant separation by the rate of change of the rectification tower upper temperature with time, then stops the electric heater heating, closes the two-way valve at the separation circuit inlet, and separates the separation circuit outlet. By fully closing the expansion device, the refrigerant concentration in the main circuit can be kept constant after the completion of the refrigerant separation, and a separation circuit with less heat loss can be realized.

Embodiment Hereinafter, a control device for a refrigerating apparatus according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a refrigeration cycle diagram in the embodiment of the present invention.

In the figure, 11 is a compressor, 12 is a four-way valve, 13 is an outdoor heat exchanger, 14 is a main expansion device, and 15 is an indoor heat exchanger, which are sequentially connected in an annular fashion to form a main circuit. On the other hand, a check valve bridge 16 is connected to the inlet and outlet of the main expansion device 14 in parallel with the main expansion device 14 so that the check valve bridge is always on the high-pressure refrigerant side.
The outlet of 16 and the inlet of the rectification tower 20 are connected via a two-way valve 17 by a pipe 19 wound with an electric heater 18.
The lower outlet of the rectification tower 20 and the inlet of the check valve bridge 16 which is always on the low-pressure refrigerant side are connected via a sub-throttle device 21 that can be fully closed, and a condenser 22 and a reservoir are provided above the rectification tower 20. And a reservoir 23, and the reservoir 23 is connected to the rectification column 20 in an annular shape to form a separation circuit.
24 are configured. Reference numeral 25 is a temperature sensor for detecting the temperature above the rectification column 20.

Next, in FIG. 2, the control circuit is a microcomputer (hereinafter referred to as LSI) 26 for controlling the entire refrigeration system, and a rectification tower 2
0 Temperature sensor 25 that detects the temperature at the top and temperature detection circuit 2
7, a resistance circuit 28 that outputs the set temperature change rate α, an electric heater 18, a step motor 29 that controls the opening degree of the auxiliary expansion device 21, and a coil 30 that opens and closes the two-way valve 17.

Explaining the block diagram shown in FIG. 3 and the control circuit shown in FIG. 2, the resistance circuit 28 for outputting the set temperature change rate α shown in FIG. 2 corresponds to the temperature change rate set value shown in FIG. The temperature sensor 25 and the temperature detection circuit 27 shown in FIG.
Corresponds to the temperature detecting means in FIG. Also, in FIG.
The LSI 26 detects the electric signal T output from the temperature detecting means in FIG. 3, calculates the rate of change T / dt with respect to time t, and outputs the electric signal, and the electric signal T output from the calculating means. / dt and a comparison means for comparing and judging the set temperature change rate α to output a control signal, a memory storing the output mode for controlling the energization of the electrification heating heater 18 and the opening / closing of the sub-throttle device 21 and the two-way valve 17. It corresponds to the means for selecting one of the output modes of the storage means by the control signal output from the means and the comparison means. The electric heater 18, the step motor 29, and the coil 30 for opening and closing the two-way valve 17 shown in FIG. 2 correspond to the output means shown in FIG.

Regarding the refrigeration cycle configured as described above, it is first clarified that the completion of refrigerant separation can be detected by the rate of change of the upper temperature of the rectification column with time dT / dt.

First, the change in the case where the refrigerant separation proceeds will be described.

FIG. 5 shows changes in the refrigerant saturation temperature with respect to the refrigerant temperature when the pressure is constant. The horizontal axis represents the refrigerant concentration, and the concentration of the low boiling point refrigerant increases toward the right. From FIG. 5, when the pressure is constant, the saturation temperature decreases as the concentration of the low boiling point refrigerant increases.

Next, FIG. 6 shows a change in the temperature T in the upper part of the rectification column 20 with respect to time t when the refrigerant separation is in progress. However,
Air conditioning conditions are constant.

Separation progresses with the passage of time, the refrigerant having a high low boiling point component ratio is stored in the reservoir 23, and the refrigerant having a high low boiling point component ratio returns from the reservoir 23 to the upper portion of the rectification column 20. . Since the temperature in the upper part of the rectification column 20 is almost equal to the saturation temperature on the gas phase side with respect to the refrigerant pressure, the temperature in the upper part of the rectification column 20 gradually decreases. However, if the separation proceeds to some extent, the temperature change rate dT / dt with respect to the time t becomes small as shown in FIG. 6, and the separation stops.

Therefore, the rate of temperature change in the upper part of the rectification column 20 with respect to time dT / dt
It has been clarified that the completion of the refrigerant separation can be detected by detecting that is smaller than the set value α.

Next, a case where the refrigerant is not separated will be described.

In the case of the cooling operation, the refrigerant vapor compressed by the compressor 11 is liquefied by the outdoor heat exchanger 13 to be liquefied and reduced in pressure by the main expansion device 14, and then evaporated in the indoor heat exchanger 15 to the compressor 11. Return. The liquid refrigerant branched from the outlet of the outdoor heat exchanger 13 passes through the check valve bitch 16, the two-way valve 17, and the pipe 19 around which the electric heater 18 is wound, and enters the lower inlet of the rectification column 20. When the refrigerant is not separated, the first output mode of the storage means is selected by the selection means built in the LSI 26, and the electric heater 18 is not energized. Therefore, no vapor is generated, and the liquid refrigerant flows in through the lower inlet of the rectification column 20. As a result, the rectification action does not proceed, and the liquid refrigerant rises inside the rectification column 20, enters the reservoir 23, and returns to the rectification column 20 again. Then, the pressure is reduced by the sub expansion device 21 and merges with the main circuit side refrigerant.

In this way, the composition ratio of the low boiling point component inside the reservoir 23 does not rise, so that the composition ratio of the main circuit becomes equal to the refrigerant filling ratio.

Next, a case where the refrigerant is separated will be described.

When the second output mode of the storage means is selected by the selection means built in the LSI 26 and the electric heater 18 is energized, the liquid refrigerant that has branched from the outdoor heat exchanger 13 is heated by the electric heater 18. Partly vaporized and flows in from the lower inlet of the rectification column 20. This gas component rises in the rectification column 20 and enters the cooler 22 from the upper outlet. And it is cooled and liquefied, and the reservoir 23
Enters, and is returned to the rectification tower 20 again and descends. Further, vapor-liquid contact with vapor rising in the middle is performed, heat exchange and mass transfer form a rectification action, and a refrigerant having a large amount of low-boiling components is stored in the reservoir 23. Refrigerant with a low boiling point component flows into the main circuit through the auxiliary expansion device 21 and the check valve bridge 16.

Therefore, the low boiling point component ratio of the main circuit gradually decreases, and the high boiling point component ratio increases.

Then, as the separation proceeds to some extent, the temperature change rate dT / dt in the upper part of the rectification column 20 with respect to the time t becomes smaller, and when it becomes smaller than the set temperature change rate α, the separation completion control is performed by the comparison means of the LSI 26. The signal is output, the third output mode of the memory circuit is selected, the coil 30 is energized so as to close the two-way valve 17, and the control signal is output to the step motor 29 so as to fully close the auxiliary throttle device 21. The power to the electric heater stops.

As a result, the refrigerant concentration on the main circuit side can be kept constant, and a refrigerant separation circuit with less heat loss can be realized. In the present embodiment, the case of rectifying and storing the low-boiling-point refrigerant is described. For example, in the case of a refrigeration cycle (not shown) in which the high-boiling-point refrigerant is stored in a reservoir arranged at the bottom of the rectification column 20 Also has a similar effect.

Effects of the Invention As described above, the present invention detects the completion of the separation of the refrigerant by the rate of change of the rectification column upper temperature with respect to time, then stops the energization of the electric heating heater, and closes the two-way valve at the separation circuit inlet, By fully closing the auxiliary expansion device at the outlet of the separation circuit, the refrigerant concentration in the main circuit after the completion of the refrigerant separation can be kept constant, and a separation circuit with less heat loss can be realized.

[Brief description of drawings]

FIG. 1 is a refrigeration cycle diagram of a refrigeration system according to an embodiment of the present invention, FIG. 2 is a control circuit diagram embodying a control system of the refrigeration system, and FIG. Block diagram, FIG. 4 is a flow chart diagram of the same control device, FIG. 5 is a diagram showing changes in the refrigerant saturation temperature with respect to the refrigerant concentration when the pressure is constant, and FIG. 6 is a rectification column with respect to time when refrigerant separation is in progress. FIG. 7 is a refrigeration cycle diagram in the conventional example, and FIG. 8 is a detailed sectional view of the same rectification column. 11 …… Compressor, 12 …… Four-way valve, 13 …… Outdoor heat exchanger,
14 …… Main throttle device, 15 …… Indoor main heat exchanger, 16 …… Check valve bridge, 17 …… Two-way valve, 18 …… Electric heating heater, 19
...... Piping, 20 …… rectification tower, 21 …… sub throttle device, 22 …… cooler, 23 …… reservoir, 24 …… separation circuit, 25 …… temperature sensor.

Claims (1)

[Claims] 1. A non-azeotropic mixed refrigerant, a compressor, a four-way valve,
The outdoor heat exchanger, the main throttle device, the indoor heat exchanger are annularly connected to form a main circuit, and a check valve bridge is connected in parallel to the main throttle device at the inlet and outlet of the main throttle device, The outlet of the check valve bridge, which is always on the high-pressure refrigerant side, and the inlet of the rectification column are connected via a two-way valve by a pipe wound with an electric heater, and the lower outlet of the rectification column is always connected to the low pressure. The inlet of the check valve bridge on the refrigerant side is connected via a sub-throttle device that can be fully closed, and a condenser and a reservoir are provided at the upper part of the rectification tower, and the reservoir is a rectification tower and a ring. A refrigerating apparatus is constituted by a separation circuit connected to, the temperature detecting means for detecting the upper temperature of the rectification column and converting it into an electric signal, and the electric signal output from the temperature detecting means is inputted, and the rate of change with time is inputted. Calculating means for calculating and outputting an electric signal; and Comparing means for comparing and judging the air signal and the set electric signal and outputting a control signal; storage means for storing an output mode for controlling energization of the electric heating heater and opening / closing of the sub-throttle device and the two-way valve. Selecting means for selecting one of the output modes of the storage means by a control signal output from the comparing means, energization of the electric heating heater according to the output mode of the storage means, the sub-throttle device and the two A control device for a refrigerating apparatus, comprising an output means for controlling opening / closing of a one-way valve.