JPH0989392A - Refrigerator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the coefficient of performance of the cooling operation under the overload condition in a refrigerator using the refrigerant which contains pentafluoroethane as an ingredient. SOLUTION: A compressor 1, an outdoor heat exchanger 2, a pressure reducing mechanism 3 and an indoor heat exchanger 4 are sequentially connected to form a refrigerant circuit, the exchanger 2 is functioned as a condenser to constitute an air conditioner which conducts the cooling operation. The overload state is judged by detecting that the condensing temperature Tc detected by an outdoor heat exchanger temperature sensor 11 and the atmospheric temperature Toa detected by an atmospheric temperature sensor 12 respectively exceed predetermined reference temperatures Tcs1, Tos by a controller 6. At this time, the controller 6 controls the speed of an outdoor fan 5 to increase its air flow rate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerating device using a refrigerant containing pentafluoroethane as a component.

[0002]

2. Description of the Related Art Generally, in a refrigeration system, a compressor, a condenser,
A refrigeration cycle is configured in which a refrigerant is circulated in a refrigerant circuit including a decompression mechanism and an evaporator, and the amount of heat absorbed by the evaporator is transferred to the condenser and released. By allowing the heat source side heat exchanger to function as a condenser and the utilization side heat exchanger to function as an evaporator, cooling operations such as cooling and freezing can be performed. Further, the above-mentioned refrigerant has the property of evaporating at a pressure higher than atmospheric pressure even at a low temperature and liquefying at a relatively low pressure at room temperature, and the property of being inexpensive and not attacking copper or copper alloys. Therefore, a freon-based refrigerant such as R22 (CHClF ₂ ) has been conventionally used. However, R2 above
Since CFC-based refrigerants such as 2 are subject to CFC restrictions, they do not adversely affect ozone in the stratosphere as alternative refrigerants and have chemical characteristics such as chemical stability and flame retardancy. An alternative refrigerant with was required.

Therefore, various alternative refrigerants as described above have been proposed, and one of them is, for example, Japanese Patent Publication No. 6-914.
The thing described in the gazette can be mentioned. This alternative refrigerant is pentafluoroethane (CF ₃ CHF ₂ , hereinafter “H
It is called FC125 ". ) And difluoromethane (CH ₂ F
₂ , hereinafter referred to as "HFC32". ) And as a main component, the mixing ratio of which is about 1.0 to 55.0% by weight of HFC125 and about 99.0 to 4 of HFC32.
It has been proposed to set it to 5.0% by weight. With such a refrigerant, the adverse effect on the ozone in the stratosphere is almost negligible as compared with the fluorocarbon refrigerant such as R22.
In addition to being an azeotropic mixed refrigerant, it has the property of being flame-retardant in the air. Therefore, it was easy to handle and the apparatus was not complicated, and was suitable as an alternative refrigerant.

[0004]

The mixed refrigerant of HFC125 and HFC32 as described above generally has the property that the high pressure is higher than that of R22. For example, according to Table 4 of the specification described in Japanese Patent Publication No. 6-503832, at a condensation temperature of about 46 ° C, when R22 is used, the high pressure is 258 (psi).
50% by weight of HFC125 and 50
Refrigerant mixed with wt% of HFC32 (hereinafter referred to as "R41
0A ". ) Is 396 (psia), and the high pressure is about 1.5 times as high as when R22 is used. If the condensing temperature is higher, the high pressure will be correspondingly higher, and in such a case the performance of the compressor will be limited. Therefore, in the above-mentioned mixed refrigerant, the region where the rating is 35 ° C and the condensation temperature is relatively high is not regarded as a normal operation region, and therefore the cooling capacity of the refrigerant in such a region has not been known at all.

Therefore, the inventors of the present invention used the special compressor for the test whose performance does not have a limit even when the high pressure is relatively high.
The cooling capacity of 0A was investigated. FIG. 3 is a graph showing the results, and the coefficient of performance COP with respect to the outside air temperature.
(Ratio of cooling capacity to compression power spent to obtain it) is plotted against R22 ratio. As shown in the figure, quite surprisingly, the R410A has a property that the coefficient of performance COP ratio is rapidly reduced when the outside air temperature is 40 ° C. or higher. In other words, in such a region, the compression power required to obtain a certain cooling capacity is remarkably increased, which causes a problem of increasing the electricity bill for the user. It is considered that the cause thereof is that the thermodynamic characteristics (heat conduction etc.) of the HFC 125 are drastically lowered mainly under the overload condition as compared with the case under the normal condition due to the increase of the condensation temperature. Therefore, in order to be able to use the refrigeration system using a refrigerant containing HFC125 as a component even under overload conditions, simply replacing the compressor with one having a higher input current upper limit value is not sufficient. You can That is, under the overload condition, the coefficient of performance of the refrigerant itself, CO
This is because P is lower than in the conventional case, so that the running cost (electricity cost) of the compressor is significantly increased even if the compressor can be used.

The present invention has been made on the basis of the above new findings, and its object is to perform a cooling operation under an overload condition in a refrigeration system using a refrigerant containing pentafluoroethane as a component. To improve the coefficient of performance.

[0007]

Therefore, in the refrigerating apparatus of the first aspect, the compressor 1, the heat source side heat exchanger 2, the pressure reducing mechanism 3, and the utilization side heat exchanger 4 are sequentially connected, and pentafluoro as a component. In the refrigerating apparatus which has a refrigerant circuit using a refrigerant containing ethane HFC125 and has the heat source side heat exchanger 2 provided with the blower fan 5 functioning as a condenser to perform a cooling operation, the cooling operation is performed. The present invention is characterized in that a control unit 6 is provided for detecting that the blower fan 5 is operating under an overload condition and performing control so as to increase the air volume of the blower fan 5 as compared with that during normal operation.

In the refrigerating apparatus of the first aspect, it is possible to reduce the condensation temperature and improve the coefficient of performance COP by increasing the air volume of the blower fan 5.

According to a second aspect of the refrigeration system, the control section 6 is provided.
Is characterized in that the ambient temperature Toa of the heat source side heat exchanger 2 is higher than a predetermined reference ambient temperature Tos to detect that it is under an overload condition.

In the refrigerating apparatus of claim 2, the ambient temperature T
Since it is detected that the load condition is under the overload condition by oa, it is possible to facilitate the implementation.

Further, in the refrigerating apparatus of the third aspect, the control section 6 detects that the condensing temperature Tc of the heat source side heat exchanger 2 is higher than a predetermined reference condensing temperature Tcs1 and is under an overload condition. It is characterized in that it is.

In the refrigerating apparatus of the third aspect, the condensing temperature T
Since it is detected by c that the vehicle is under an overload condition, reliable control can be performed.

In the refrigerating apparatus of claim 4, the control unit 6 is
It is characterized in that the higher the ambient temperature Toa or the condensation temperature Tc, the higher the air volume of the blower fan 5 is controlled.

In the refrigerating apparatus of the fourth aspect, the coefficient of performance COP can be surely improved by the control in accordance with the overload condition.

In the refrigerating apparatus of claim 5, the refrigerant is approximately 5
About 50% by weight of pentafluoroethane HFC125
It is characterized in that it contains difluoromethane HFC32 in a weight percentage.

In the refrigerating apparatus of the fifth aspect, by using an azeotropic refrigerant that is easy to handle, it is possible to facilitate its implementation.

In the refrigerating apparatus of claim 6, the blower fan 5 is used.
Is driven by an AC motor, and is the control unit 6
Is characterized in that the air volume of the blower fan 5 is controlled by switching taps for energizing the AC motor.

In the refrigerating apparatus of the sixth aspect, the cost can be reduced with a simple structure.

According to a seventh aspect of the refrigeration system, the blower fan 5 is used.
Is driven by a DC motor, and the control unit 6 controls the air volume of the blower fan 5 by changing the drive voltage applied to the DC motor.

In the refrigerating apparatus of the seventh aspect, since the air volume can be adjusted linearly, the coefficient of performance COP can be further improved.

In the refrigerating apparatus of claim 8, the control section 6 is
When the condensing temperature Tc of the heat source side heat exchanger 2 exceeds a predetermined reference condensing temperature Tcs2, control is performed so as to reduce the compression capacity of the compressor 1.

In the refrigerating apparatus of claim 9, the compressor 1 is driven by an inverter, and the control unit 6 changes the driving frequency output from the inverter to control the compressor 1. The feature is that the compression capacity is controlled.

In the refrigerating apparatus of the eighth or ninth aspect, it is possible to maintain a wide operating region which has been secured conventionally.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, specific embodiments of the refrigeration apparatus of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a refrigerant circuit diagram of an air conditioner to which the present invention is applied. In this air conditioner, a discharge pipe 1a and a suction pipe 1b of a compressor 1 are connected to a four-way switching valve 7 as shown in the figure, and an outdoor fan (blower fan) 5 is attached to the four-way switching valve 7. An attached outdoor heat exchanger (heat source side heat exchanger) 2, a pressure reducing mechanism 3 including a capillary tube 3a and an electric expansion valve 3b, and an indoor heat exchanger (use side heat exchanger).
4 are sequentially connected in an annular shape by a first gas pipe 19a, a first liquid pipe 19b, a second liquid pipe 19c and a second gas pipe 19d. Further, in the figure, 11 is an outdoor heat exchanger temperature sensor that detects the condensation temperature Tc and the like in the outdoor heat exchanger 2, and 12 is an outdoor air temperature sensor that detects the outdoor air temperature (ambient temperature) Toa. These sensors 11,
Condensation temperature Tc or outside air temperature Toa detected in 12
Are input to the control unit 6, which is configured by using a microcomputer or the like, and controls the inverter of the compressor 1 and the speed of the outdoor fan 5. . In the figure, 8 is an accumulator provided to prevent liquid compression in the compressor 1, 13 is an indoor heat exchanger temperature sensor, and the electric expansion based on the output signal of the sensor 13 is used. Control of the valve 3b and the like is performed, but since this control is the same as the conventional one, detailed description thereof will be omitted.

In the refrigerant circuit constructed as described above, R410A is used as the refrigerant. This R4
10A is 5% by weight of HFC125 and 5 as described above.
An azeotropic refrigerant containing 0% by weight of HFC32,
It is a typical alternative refrigerant that has flame retardancy in air and is easy to handle.

Next, the speed control of the outdoor fan 5 by the control section 6 and the inverter control of the compressor 1 will be described with reference to the flow chart shown in FIG.

First, when the compressor 1 is driven to start the operation of the air conditioner, it is determined in step S1 whether or not the operation is a cooling operation. In this air conditioner, in the refrigerant circuit shown in FIG. 1, by switching the four-way switching valve 7 in the solid line direction, the outdoor heat exchanger 2 functions as a condenser and the indoor heat exchanger 4 functions as an evaporator. To perform cooling operation. On the other hand, by switching the four-way switching valve 7 in the direction of the broken line, the outdoor heat exchanger 2 functions as an evaporator and the indoor heat exchanger 4 functions as a condenser to perform heating operation. If the heating operation is in progress, step S1
If it is determined in step S5, the process proceeds to step S5, in which the normal control similar to the conventional one is only performed. Therefore, hereinafter, the description will be made assuming that the air conditioner is in the cooling operation.

When it is determined in step S1 that the cooling operation is being performed, the process proceeds to step S2, in which it is determined whether the cooling operation is being performed under an overload condition. That is, first, the outside air temperature Toa input from the outside air temperature sensor 12 is compared with a preset predetermined reference outside air temperature (reference ambient temperature) Tos. This reference outside air temperature Tos
Is set to about 43 to 46 ° C. with respect to the rating of 35 ° C., and is set as a temperature at which it can be determined that an overload condition exists. Here, if the outside air temperature Toa is equal to or lower than the reference outside air temperature Tos, it is determined that the cooling operation is not under the overload condition, and the process proceeds to step S5. On the other hand, when the outside air temperature Toa is higher than the reference outside air temperature Tos, the condensation temperature Tc input from the outdoor heat exchanger temperature sensor 11 is further compared with a preset first reference condensation temperature Tcs1. The first reference condensing temperature Tcs1 is set to about 50 to 55 ° C. at which the heat transfer performance of the HFC 125 sharply decreases, and in combination with the judgment based on the outside air temperature Toa, the cooling operation is performed under the overload condition. It is possible to determine that something is certain and accurate. If the condensing temperature Tc is equal to or lower than the first reference condensing temperature Tcs1, it is determined that the cooling operation is not under the overload condition, and the process proceeds to step S5, while the condensing temperature Tc is higher than the first reference condensing temperature Tcs1. In this case, it is determined that the cooling operation is performed under the overload condition.

When it is determined in step S2 that the cooling operation is being performed under the overload condition, the process proceeds to step S3, and the speed of the outdoor fan 5 is controlled to increase the air volume. Since the outdoor fan 5 is driven by the AC motor (not shown) in the air conditioner, the speed control here is performed by switching the taps for energizing the AC motor. For example, if the low-speed tap L is currently energized, in step S3 the energization is switched to the medium-speed tap M, and if the medium-speed tap M is energized, it is switched to the high-speed tap H. is there. However, if the high-speed tap H is already energized, the speed cannot be increased any further, so step S3 is terminated without switching the energization tap, and the process proceeds to step S4.

In the next step S4, the high pressure control of the compressor 1 is performed by the inverter. That is, step S2
The condensing temperature Tc detected in 1 is compared with a preset second reference condensing temperature Tcs2, and when the condensing temperature Tc is higher than the second reference condensing temperature Tcs2, an inverter (control unit 6
The drive frequency output from the (incorporated in) is reduced, thereby reducing the compression capacity of the compressor 1. The second reference condensing temperature Tcs2 at this time is set as a temperature at which the high pressure does not rise and the input current value of the compressor 1 exceeds the limit. When the above control is completed, the process returns to step S1 and the above routine is repeated.

In the air conditioner configured as described above,
It is detected that the cooling operation is performed under the overload condition based on the outside air temperature Toa and the condensation temperature Tc. When it is detected that the vehicle is operating under an overload condition, the amount of air blown by the outdoor fan 5 is increased, so that the overload state can be eliminated. Therefore R4
It is possible to prevent the coefficient of performance COP of 10 A from significantly lower than that of R22, and solve the problem of the alternative refrigerant R410A that the user's electricity bill becomes high. In addition, such outdoor fan control avoids cooling operation under overload conditions, and high-voltage control is performed by the inverter on top of that.Therefore, a wide range of operations secured in conventional air conditioners using CFC-based refrigerants is used. The area can be maintained in this air conditioner as well. Further, in the above air conditioner, the high pressure control is performed by the inverter control of the compressor 1, but this may be performed by repeating the operation and the stop using a compressor having a constant compression capacity. By doing so, the structure is simplified and the cost can be reduced.

Although the specific embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and can be implemented with various modifications within the scope of the present invention. For example, in the air conditioner, as shown in step S2 of the flowchart of FIG. 2, the overload state is determined using both the outside air temperature Toa and the condensing temperature Tc to ensure its certainty and accuracy. . However, this may be determined by using only the outside air temperature Toa or the condensation temperature Tc, which makes it possible to simplify the control. However, when only the outside air temperature Toa is detected in step S2, step S4 is performed for high pressure control.
In, it is necessary to separately detect the condensation temperature Tc.

Further, in the air conditioner, whether or not it is in the overload state is detected in step S2, and if it is in the overload state, a simple control is performed in which the speed of the outdoor fan 5 is increased as compared with the normal time to reduce costs. I am trying to However, this makes it possible to determine the degree of the overload state by further setting several stages of reference temperatures, and the higher the outside air temperature Toa or the condensation temperature Tc, the higher the speed of rotation of the taps. The control may be such that the energization is switched. Although this makes the control somewhat complicated, it is possible to eliminate the overload state quickly and reliably. Further, in the above air conditioner, the blower fan is driven by the AC motor, and the air flow rate is controlled by tap control, but this has a simple configuration in which the air flow rate is controlled by changing the applied voltage value using the DC motor. It may be performed. With such a configuration, linear control can be performed particularly when performing control such that the speed of the outdoor fan 5 is successively increased according to the height of the outside air temperature Toa or the condensation temperature Tc as described above.
The coefficient of performance COP can be further improved.

In the air conditioner, R41 is used as a refrigerant.
0A was used. As mentioned above, this refrigerant is extremely easy to handle as an alternative refrigerant and has been certified by the ASHRAE (American Society of Heating Refrigerating and Air Conditioning Engineers) standard. Is. However, as long as the refrigerant contains HFC125 as its component, the cooling efficiency can be improved by applying the present invention not limited to the above R410A. Furthermore, although an example in which it is configured as an air conditioner has been shown above, it can be applied to refrigerating cases of other supermarkets, etc., and even more remarkable effects can be obtained particularly in countries and regions with high temperatures.

[0036]

In the refrigerating apparatus of the first aspect, the coefficient of performance can be improved by lowering the condensing temperature, so that the refrigerating efficiency can be improved and the running cost can be reduced.

Further, in the refrigerating apparatus of the second aspect, since it is detected that the overload condition exists due to the ambient temperature, it is possible to facilitate the implementation.

Further, in the refrigerating apparatus of the third aspect, since it is detected that the engine is under an overload condition by the condensing temperature,
It becomes possible to perform reliable control.

In the refrigerating apparatus of the fourth aspect, the coefficient of performance can be surely improved by the control in accordance with the overload condition.

In the refrigerating apparatus of the fifth aspect, by using an azeotropic refrigerant that is easy to handle, it is possible to facilitate its implementation.

In the refrigerating apparatus of the sixth aspect, the cost can be reduced with a simple structure.

In the refrigerating apparatus of the seventh aspect, since the air volume can be adjusted linearly, the coefficient of performance can be further improved.

In the refrigerating apparatus of the eighth or ninth aspect, it is possible to maintain a wide operating region which has been secured conventionally.

[Brief description of drawings]

FIG. 1 is a refrigerant circuit diagram of an air conditioner to which the present invention is applied.

FIG. 2 is a flowchart showing an operation of a control unit provided in the air conditioner.

FIG. 3 is a graph showing the cooling capacity of an alternative refrigerant.

[Explanation of symbols]

 1 compressor 2 outdoor heat exchanger 3 decompression mechanism 4 indoor heat exchanger 5 outdoor fan 6 control unit Toa outside air temperature Tc outdoor heat exchanger temperature Tos reference outside air temperature Tcs1 first reference condensation temperature Tcs2 second reference condensation temperature

Front page continuation (72) Inventor Kengo Murayama 2 at 1000 Otani, Okamoto-cho, Kusatsu-shi, Shiga Daikin Industry Co., Ltd. Shiga Works (72) Inventor Yoichi Onuma 2 Daikin at 1000 Otani, Okamoto-cho, Shiga Prefecture Industrial Co., Ltd. Shiga Works

Claims (9)

[Claims] 1. A compressor (1), a heat source side heat exchanger (2),
The decompression mechanism (3) and the utilization side heat exchanger (4) were sequentially connected, and pentafluoroethane (HFC1) was used as a component.
25) having a refrigerant circuit using a refrigerant such as
In a refrigerating apparatus that performs a cooling operation by causing the heat source side heat exchanger (2) provided with a blower fan (5) to function as a condenser, it is detected that the cooling operation is performed under an overload condition. A refrigerating apparatus comprising a control unit (6) for performing control so as to increase the air volume of the blower fan (5) more than that during normal operation. 2. The control unit (6) is configured such that an ambient temperature (Toa) of the heat source side heat exchanger (2) is a predetermined reference ambient temperature (Ta).
The refrigerating apparatus according to claim 1, wherein the refrigerating apparatus is configured to detect that the vehicle is under an overload condition by being higher than os). 3. The control unit (6) is configured so that the condensation temperature (Tc) of the heat source side heat exchanger (2) is a predetermined reference condensation temperature (Tc).
The refrigerating apparatus according to claim 1, wherein the refrigerating apparatus is adapted to detect an overload condition by being higher than s1). 4. The control unit (6) is configured to control the ambient temperature (T
The refrigerating apparatus according to claim 2 or 3, wherein the higher the oa) or the condensing temperature (Tc), the higher the air volume of the blower fan (5) is controlled. 5. The refrigerant according to claim 1, wherein the refrigerant contains approximately 50% by weight of pentafluoroethane (HFC125) and approximately 50% by weight of difluoromethane (HFC32). Refrigeration equipment. 6. The blower fan (5) is driven by an AC motor, and the control unit (6) changes the air volume of the blower fan (5) by switching taps for energizing the AC motor. The refrigerating apparatus according to any one of claims 1 to 5, wherein the refrigerating apparatus is controlled. 7. The blower fan (5) is driven by a DC motor, and the control section (6) changes the drive voltage applied to the DC motor to blow the blower fan (5). 6. The refrigerating apparatus according to any one of claims 1 to 5, characterized in that the air flow rate is controlled. 8. The controller (6) is configured such that the condensation temperature (Tc) of the heat source side heat exchanger (2) is a predetermined reference condensation temperature (Tc).
The refrigerating apparatus according to any one of claims 1 to 7, characterized in that, when s2) is exceeded, control is performed so as to reduce the compression capacity of the compressor (1). 9. The compressor (1) is driven by an inverter, and the control unit (6) changes the driving frequency output from the inverter to thereby drive the compressor (1). 9. The refrigerating apparatus according to claim 8, wherein the compression capacity is controlled.