JPH0665944B2 - Refrigeration cycle - Google Patents

Description

The present invention relates to a refrigeration cycle using a mixed refrigerant.

[Background of the Invention]

The refrigerant used in the refrigeration cycle usually has a single component, but in this case, when used in a heat pump type air conditioner, there is a problem of low capacity at low outside air temperature. When the outside air temperature decreases, the refrigerant pressure inside the evaporator decreases, the specific volume of the refrigerant at the compressor inlet increases, and the capacity decreases. As a means for increasing the capacity of low outside air temperature, there is a means for controlling the compressor rotation speed. However, if the outside air temperature significantly decreases, as shown in Fig. 2, even if the rotation speed is increased, the pressure loss increases and the capacity decreases. The disadvantage is that the increase in on the other hand,
When a low boiling point refrigerant whose capacity is not significantly reduced even at low outside air temperature is used, the discharge pressure becomes high and the efficiency is lowered when the capacity is high. Further, during the defrosting operation, the pressure loss is large and the refrigerant circulation amount is small. Therefore, the compressor input is small, the heat energy of the refrigerant flowing out of the compressor is small, and the defrosting time is long. Therefore, using a mixed refrigerant consisting of a high-boiling point refrigerant and a low-boiling point refrigerant, operating at high boiling point refrigerant during cooling operation and heating operation when the outside air temperature is high, low boiling point refrigerant at low outside air temperature and defrosting operation A refrigeration cycle to which is added is known.

As a method for separating a high-boiling-point refrigerant and a low-boiling-point refrigerant, a method using a distiller is known (JP-A-59-197761, JP-A-59-197763, JP-A-54-2561). Gazette).

However, the method using a distiller complicates the apparatus.

[Object of the Invention]

The object of the present invention is to eliminate the above problems, a simple structure, depending on the outside air temperature and operating conditions, the concentration of the low boiling point refrigerant is changed, the capacity deterioration at low temperature is small and the defrosting time is short and the refrigeration cycle is short. To provide.

[Outline of Invention]

In order to achieve the above object, at any point of the evaporator outlet and the compressor inlet, bypass the container containing the adsorbent that can selectively adsorb only the low boiling point refrigerant, and during normal operation, the low boiling point refrigerant in the adsorbent Is adsorbed and is operated only with the high-boiling-point refrigerant, and the adsorbent is heated to release the low-boiling-point refrigerant and operate with the mixed refrigerant at the time of low outside temperature and defrosting operation. As the adsorbent, for example, when using zeolite, by utilizing the property of not adsorbing a substance having a molecular diameter larger than the pore size of zeolite, by using, for example, R115 as a high boiling point refrigerant, for example R13B1 as a low boiling point refrigerant, the molecular diameter Only R13B1 having a small value can be selectively adsorbed. Further, by heating the adsorbent, the adsorbed refrigerant can be released again.

FIG. 3 shows a change in heating capacity when the outside air temperature changes. In the case of R115 alone, the capacity decreases as the outside air temperature decreases, and the capacity decrease and the efficiency decrease are remarkable especially at low outside air temperature. However, the addition of 10% of low-boiling point refrigerant causes less deterioration of the capacity at low ambient temperature and high efficiency. However, when the outside air temperature becomes high, the latent heat of vaporization becomes small and the efficiency decreases, and the discharge pressure of the compressor becomes high, and the reliability of the refrigeration cycle decreases. Therefore, when the ambient temperature is low, the mixed refrigerant is used, and the other high-boiling-point refrigerants are used to operate efficiently.

Further, by operating the mixed refrigerant during the defrosting operation, the refrigerant circulation amount increases, the compressor input increases, and the defrosting ends in a short time.

Example of Invention

The first embodiment of the present invention will be described below with reference to FIG.
FIG. 1 is a schematic diagram of a refrigeration cycle showing a first embodiment. In FIG. 1, 1 is a compressor, 2 is cooling, and a four-way switching valve that switches the flow of refrigerant during heating operation, 3 is an outdoor heat exchanger, 4 is a cooling decompressor, and 5 is a check valve for heating. 6 is a heating decompressor, 7 is a cooling check valve, 8 is an outdoor heat exchanger,
Reference numeral 9 is a receiver for storing excess refrigerant, 10 is a container for containing an adsorbent (for example, zeolite) 12 that is prevented from flowing out by a mesh 11, 13 is a heater for heating the adsorbent, 14
Is a two-way valve A as a control valve, 15 is a two-way valve B as a control valve, 16 is a thermistor A for measuring the outside air temperature, 20 is a thermistor for measuring the outlet temperature of the outdoor heat exchanger 8 during heating operation. B. A high boiling point refrigerant (for example,
R115) and a low boiling point refrigerant (for example, R13B1) are enclosed.

Next, a control diagram of the first embodiment is shown in a block diagram in FIG. The same reference numerals as those in FIG. 1 represent the same parts. twenty one
Is an outside air temperature determination unit, 22 is a logical sum calculation unit, 23 is a timer A that sets the output to 1 after T ₁ time when the output of the logical sum calculation unit 22 becomes 1, 24 is a two-way valve A14 and a two-way valve B15 After the output of the logical sum operation unit 22 becomes a logical "1", the drive units A and 25 for opening and closing t ₁
Timer C, 31 the timer B, 26 prevents the drive unit B29 to be supplied to the heater 13 outdoor heat exchanger temperature determination unit, the 30 enters the predetermined time t ₂ defrosting that only the output "1" Time Is a logical product computing unit, 32 is a logical product computing unit 31, a timer D that sets the output to “1” _one hour after the output becomes “1”, 33 is an inverter, and 34 is the four-way switching valve 2 on the cooling operation side. The drive unit C, 36 for switching to the heating operation side is a feedback unit for changing the setting reference of the outdoor heat exchanger temperature determination unit 29 according to the output “1” or “0” of the OR operation unit 31,
Reference numeral 37 is a cooling changeover switch that sets the output of the drive unit C34 to "0" regardless of the output of the inverter 33 to set the four-way changeover valve 2 to the cooling operation side. The operation of the block diagram configured as above will be described with reference to the time charts of FIGS. 5 and 6. FIG. 5 is a time chart during heating operation, and FIG. 6 is a time chart during defrosting operation. During cooling operation, set the cooling switch 37 to the cooling side
The output of 34 becomes "0" and the four-way switching valve 2 becomes the cooling operation side. Further, during the cooling operation, since the outside air temperature and the temperature of the outdoor side exchanger 8 are high, the temperatures detected by the thermistor A16 and the thermistor B20 are high, and the outside air temperature determination unit 21 and the outdoor heat exchanger temperature determination unit 29 are Both outputs become "0" and OR operation section
The output of 22 becomes 0, the outputs of the drive unit A24 and the drive unit B26 become "0", the two-way valve A14 and the two-way valve B15 are opened, and the heater 13 is turned off.

Next, the heating operation will be described. When the temperature detected by the thermistor A16 is higher than the reference temperature T ₁ of the outdoor air temperature determination unit 21, the output of the outdoor air temperature determination unit 21 is “0”, while the temperature of the thermistor B20 is the outdoor heat exchanger temperature. When the temperature is higher than the reference temperature T ₂ set by the determination unit 29, the output of the outdoor heat exchanger temperature determination unit 29 becomes “0”, and the OR operation unit
The output of 22 becomes "0", the two-way valve A14 and the two-way valve A15 are opened, and the heater 13 is turned off. Moreover, the output of the comparator 33 becomes 1, and the four-way switching valve 2 is set to the heating operation side by the drive unit C34. Next, when the outside air temperature decreases and the detection temperature of the thermistor A16 falls below the reference temperature T ₁ of the outside air temperature determination unit 21,
The output of the outside air temperature determination unit 21 becomes “1”, and the OR operation unit 22
Output becomes 1. Therefore, the output of the timer B25 becomes "1" for t ₁ hours, and the heater 13 is energized during this time. On the other hand, the output of timer A23 becomes "1" ₁ hour after t, and the two-way valve 1
4, 2-way valve B15 is closed. When the outside air temperature rises in this state and becomes higher than the reference temperature T _{1 of the} outside air temperature determination unit 21, the output of the outside air temperature determination unit 21 becomes “0”, the output of the logical sum operation unit 22 becomes “0”, and the timer A23 output is “0”, two-way valve A14,
The two-way valve B15 opens.

The defrosting operation will be described. When frost adheres to the outdoor heat exchanger 8, the heat exchanging capability is lowered, the temperature of the outdoor heat exchanger 8 is lowered, and the temperature detected by the thermistor B is lowered. When the temperature detected by the thermistor B becomes lower than the reference temperature T _{1 of} the outdoor heat exchanger temperature determiner 29, the output of the outdoor heat exchanger temperature determiner 29 becomes “1”. Meanwhile, since the last defrosting is completed, the output of the timer C30 becomes a predetermined time t ₂ is "1"
Then, the output of the AND operation unit 31 becomes "1", and the defrosting process starts. First, the output of the logical sum operation unit 22 becomes "1", the heater 13 is energized for t ₁ time, and then the two-way valve A14 and the two-way valve B15 are closed. On the other hand, t ₁ hours after the output of the AND operation unit 31 becomes “1”, the output of the timer C32 becomes “1” and the output of the comparator 33 becomes 0.
Therefore, the four-way switching valve 2 is in the defrosting operation (in the same direction as the cooling operation). Further, when the output of the logical product calculation unit 31 becomes 1, the feedback unit 36 changes the reference temperature of the outdoor heat exchanger temperature determination unit 29 from T ₂ to T ₃ . Therefore, when defrosting ends and the temperature of the outdoor heat exchanger 8 rises, the temperature of the circulator B20 rises, and when it becomes higher than the reference temperature T _{3 of} the outdoor heat exchanger temperature determiner 29, the outdoor heat exchanger. The output of the temperature determiner 29 becomes "0", the output of the OR operation unit 22 becomes "0", the output of the comparator 33 becomes "1", and the two-way valve A14 and the two-way valve B15 open the four-way switching valve 2 Return to the heating side. Also, the timer C30 is reset.

The operation of the refrigeration cycle in the above control mode will be described.

During the cooling operation, the four-way switching valve 2 is on the cooling side, the two-way valve 14 and the two-way valve B15 are open, and the adsorbent 13 is in the adsorption state of the low boiling point refrigerant. The high-temperature, high-pressure refrigerant gas in the compressor 1 passes through the four-way switching valve 2 and radiates heat in the outdoor heat exchanger 8 to become a high-pressure liquid refrigerant, and then the cooling check valve 7 and the liquid receiver 9 are used. The pressure is reduced by the passage cooling decompressor 4. The low-pressure refrigerant absorbs heat in the indoor heat exchanger 3 to become a gas refrigerant, and then passes through the four-way switching valve 2 to return to the compressor 1 and the cycle is repeated. At this time, since the two-way valve A14 and the two-way valve B15 are open, the part of the gas refrigerant returning from the four-way switching valve 2 to the compressor 1 flows through the container 10, and the low boiling point refrigerant is mixed in the refrigeration cycle. If so Adsorbent 13
Therefore, the refrigeration cycle is usually operated only with a high boiling point refrigerant.

Next, the heating operation will be described. When the temperature detected by the thermistor 16 is higher than T ₁ , the four-way switching valve 2 is opened on the heating side, and the two-way valve A14 and the two-way valve B15 are opened. The refrigerant gas that has become high temperature and high pressure in the compressor 1 passes through the four-way switching valve 2 and radiates heat in the indoor heat exchanger 3 to become high pressure liquid refrigerant, and then the check valve 5 for heating and the receiver 9 The pressure is reduced by the heating pressure reducer 6. The low-pressure refrigerant absorbs heat in the outdoor heat exchanger 8 to become a gas refrigerant, and then passes through the four-way switching valve 2 to return to the compressor 1 to repeat the cycle. At this time, two-way valve A14, two-way valve B15
Since it is open, it is operated only with the high boiling point refrigerant as in the cooling operation. When the outside air temperature decreases and the temperature detected by the thermistor 16 becomes T ₁ or less, the heater 13 is energized,
The adsorbent 12 is heated. Therefore, the low boiling point refrigerant adsorbed by the adsorbent 12 is released and enters the refrigeration cycle through the two-way valve B15. When the time t ₁ required for release elapses, the two-way valve A 1
4. Close the two-way valve B15 to stop energizing the heater 13. Therefore, the refrigeration cycle is operated with a mixed refrigerant of a high-boiling-point refrigerant and a low-boiling-point refrigerant, even if the evaporation temperature of the outdoor heat exchanger 8 decreases, the pressure does not decrease, the volumetric flow rate decreases, the pressure loss decreases, High efficiency and large capacity. This embodiment is a container when the two-way valve A14 and the two-way valve B15 are open.
Control valves are provided before and after the container 10 so that the refrigerant flows through the inside of the container 10. However, when the time required for adsorption may be long, the same effect can be obtained by using only one of the two-way valves.

Next, the defrosting operation will be described. If the outside air temperature decreases and frost adheres to the outdoor heat exchanger 8, the heat exchange capacity decreases and the evaporation temperature decreases. When the temperature detected by the thermistor B becomes T ₂ or less, defrosting operation starts. First, energize the heater 13,
After heating the adsorbent 12 to release the low boiling point refrigerant adsorbed on the adsorbent 12, the two-way valve A14 and the two-way valve B15 are closed and the heater
Stop energizing 13. At that time, the four-way switching valve 2 is also on the cooling operation side, and defrosting is started. Therefore, during defrosting, the high-temperature high-pressure gas discharged from the compressor 1 is radiated by the outdoor heat exchanger 8 to melt the attached frost, and the cooling check valve 7 and the cooling decompressor are operated. 4. The cycle of returning to the compressor 1 through the indoor heat exchanger 3 and the four-way switching valve 2 is performed. Thermistor 20
When the temperature detected at is above T ₃ , normal heating operation is resumed. At this time, since the mixed refrigerant is operated, the pressure in the cycle is higher than that in the case of using the high boiling point refrigerant, and the volume flow rate is small, so that the pressure loss is small and the refrigerant circulation amount is large. Therefore, the input of the compressor is increased, and the defrosting time can be shortened.

A second embodiment of the present invention is shown in FIG. FIG. 7 is a schematic diagram of the refrigeration cycle of the second embodiment. In FIG. 7, the same symbols as in FIG. 1 represent the same parts. The point different from the first embodiment is that instead of the two-way valve B15, a three-way valve 17 (which turns to the four-way switching valve 2 side in the OFF state) that switches the refrigerant flow to the compressor 1 to the four-way switching valve 2 and the container 10 is used. It is a point. A block diagram of the second embodiment is shown in FIG. 8 and a time chart after the logical sum operation unit 22 is shown in FIG. The difference from the first embodiment is that when the output of the OR operation section 22 is "1", the outputs of the drive section D38 and the OR operation section 22 that close the two-way valve A are "1".
Timer E39, which sets the output to "1" for t ₁ hours when
The drive unit E switches the three-way valve 17 to the container 10 when the output of the timer E39 is "1". The operation configured as above will be described. In cooling operation and when the temperature of the thermistor 16 is higher than the reference temperature T ₁ , the two-way valve A14 is opened and the three-way valve 17
Becomes the four-way switching valve 2 side, and the same operation as in the first embodiment is performed. When the output of the OR operation unit 22 becomes 1 at the time of low outside temperature and defrosting, the two-way valve A14 is closed and the three-way valve 17 is operated for t ₁ hour.
Turns on the container 10 side and the heater 13 to release the low boiling point refrigerant adsorbed by the adsorbent 12. This makes the adsorbent
As the temperature of 12 rises, the pressure inside the container 10 drops to near vacuum. Therefore, as shown in FIG.
The amount of the low-boiling-point refrigerant adsorbed on the adsorbent 12 can be changed significantly as compared with the case where only the temperature is changed, and the adsorbent 12 can be reduced. Also, instead of using less adsorbent 12,
The time t ₁ can be shortened. Low boiling t ₁ hour after the release end of the refrigerant two-way valve A14 is closed, three-way valve 17 is in the four-way changeover valve 2 side, energization of the heater 13 performs the first embodiment the same operation and turned off .

A third embodiment of the present invention is shown in FIG. 11 and FIG. Fig. 11
12, the same reference numerals as those in FIG. 1 represent the same parts. The difference from the first embodiment is that instead of the heater 13, a three-way valve B18 is provided at the outlet of the compressor 1 and the container 10 is provided from one outlet of the three-way valve B18.
That is, a pipe is provided which passes through the radiator 19 and returns to the connection pipe of the refrigeration cycle. When the output of the timer B25 becomes 1, the three-way valve B18 is driven by the drive unit B26 and moves to the container 10 side. With this configuration, when the low-boiling-point refrigerant is discharged from the adsorbent 12, the three-way valve B18 is set to the container 10 side so that the high-temperature and high-pressure gas refrigerant exiting the compressor 1 passes through the three-way valve B18. ,
The radiator 19 radiates heat, heats the adsorbent 12, and returns to the refrigeration cycle again. Therefore, it is not necessary to provide a heater,
Power consumption can be reduced. Except when the low boiling point refrigerant is discharged, the same effect as that of the first embodiment is obtained by setting the three-way valve B18 to the four-way switching valve 2 side.

〔The invention's effect〕

According to the present invention, it is possible to increase the concentration of the low boiling point refrigerant in the refrigeration cycle at a low temperature and in the defrosting operation with a simple structure, reduce the pressure loss, and increase the capacity with high efficiency. Further, since the refrigeration cycle is operated only with the high boiling point refrigerant except when the temperature is low, there is no decrease in efficiency at this time. Moreover, the compressor input during the defrosting operation increases, and the defrosting time becomes short.

[Brief description of drawings]

FIG. 1 is a refrigeration cycle diagram showing a first embodiment of the present invention,
Fig. 2 shows the change in capacity when the compressor speed changes,
Fig. 4 shows the capacity and efficiency change depending on the type of refrigerant, Fig. 4 is a block diagram of the first embodiment of the present invention, Fig. 5 is a time chart during heating operation, Fig. 6 is a time chart during defrosting operation, FIG. 7 is a refrigeration cycle diagram showing a second embodiment of the present invention, FIG. 8 is a block diagram of the second embodiment, FIG. 9 is a time chart, and FIG. 10 is zeolite R1.
FIG. 11 is a diagram showing an adsorption amount of 3B1, FIG. 11 is a refrigeration cycle diagram showing a third embodiment of the present invention, and FIG. 12 is a block diagram of the third embodiment of the present invention. 10 …… Container 11 …… Mesh 12 …… Adsorbent 13 …… Heater 14 …… Two-way valve A 15 …… Two-way valve B 16 …… Thermistor A 17 …… Three-way valve 18 …… Three-way valve B 19 …… Radiator 20 …… Thermistor B

Claims (1)

[Claims] 1. A four-way switch in a refrigeration cycle in which at least a compressor, a four-way switching valve, an indoor heat exchanger, a pressure reducer, and an outdoor heat exchanger are connected by pipes to enclose a high boiling point refrigerant and a low boiling point refrigerant. A container enclosing an adsorbent capable of selectively adsorbing the low boiling point refrigerant from any position of the valve and the pipe at the compressor inlet is connected by a branch pipe, and the branch pipe is provided with a control valve capable of opening and closing the branch pipe, and The container is provided with a heater capable of heating the adsorbent, and at the time of defrosting operation start and low outside air temperature, the control valve is opened for a certain period of time to heat the heater to remove the low boiling point refrigerant adsorbed by the adsorbent. After discharging, the control valve is closed to operate with a mixed refrigerant of a low boiling point refrigerant and a high boiling point refrigerant.