JPH1144499A - Refrigerating cycle controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the heat transfer efficiency of a refrigerant and improve the efficiency of a heat exchanger by reducing the number of paths of the refrigerant entering the heat exchanger for transferring heat between fluids such as the refrigerant and air when the flow rate of the refrigerant is low. SOLUTION: A refrigerating cycle controller comprises a heat exchanger 4 having at least two or more paths, a detecting means 31 for substantially detecting the flow rate of a refrigerant flowing in the paths, a path number determining means for determining the number of paths in the heat exchanger 4 so as to be decreased, when the flow rate of the refrigerant detected by the detecting means 31 is low and a switching means for switching the number of paths based on a signal from the path number determining means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigeration cycle system in which the number of passes of a heat exchanger is switched in order to improve the heat exchanger efficiency of a heat exchanger for transferring heat between a refrigerant and air fluid. The present invention relates to a refrigeration cycle control device.

[0002]

2. Description of the Related Art Conventionally, in order to switch the communication relationship of a plurality of pipelines, for example, when the flow direction of a refrigerant is reversed,
Some use a pilot-driven four-way valve.

[0003] As a conventional example, those described in Japanese Patent Application Laid-Open Nos. 8-145490 and 7-32460 will be described with reference to FIG.

[0004] A heat exchanger 81 having a plurality of refrigerant pipes 84 penetrating therethrough, branch pipes 82a and 82b, and a four-way valve 83 as refrigerant switching means.

The one disclosed in Japanese Patent Application Laid-Open No. 8-145490 always prevents the temperature difference between the refrigerant and the air flow from decreasing so as to correspond to the non-azeotropic mixed refrigerant having a temperature gradient, and has the same heat as the single refrigerant. In order to obtain an exchange amount, the four-way valve 83 is switched according to an operation mode such as a heating operation or a cooling operation, and the number of paths in the heat exchanger 81 is switched to a small number.

[0006] Further, in the apparatus disclosed in Japanese Utility Model Laid-Open Publication No. 7-32460, especially in the heating operation, the path balance in the path inside the outdoor heat exchanger is poor, so that the heating performance is reduced from two paths. It has been switched to one pass.

That is, conventionally, in the same heat exchanger, the number of passes is switched during the evaporation process or the condensation process. However, when the flow rate of the refrigerant is small as intended by the present invention, the number of passes is reduced. There is no disclosure of a technical idea of increasing the heat transfer coefficient of the refrigerant by reducing the heat transfer rate and improving the heat exchanger efficiency.

Conventionally, a control apparatus for improving the performance of a heat exchanger for a heat pump air conditioner corresponding to a non-azeotropic refrigerant mixture has been described with respect to alternative refrigerant candidates due to the social background as an environmental problem such as depletion of the ozone layer. However, there is no single refrigerant or azeotropic refrigerant mixture.

[0009]

In the above-mentioned conventional configuration,
In the heat exchange, it was possible to switch to the same number of different paths, but the number of passes was not reduced when the flow rate of the refrigerant was small. Therefore, when the flow rate of the refrigerant is small, the number of passes cannot be reduced.

[0010] Further, since the mode is switched to one pass or two passes according to the operation mode, the heat transfer coefficient decreases when the refrigerant flow rate is low in the two passes, and the heat exchanger efficiency decreases,
Another problem is that when the flow rate of the refrigerant is large in one pass, the pressure loss increases and the heat exchanger efficiency decreases.

Accordingly, an object of the present invention is to improve the heat exchanger efficiency by reducing the number of passes when the flow rate of the refrigerant is low, thereby increasing the heat transfer coefficient of the refrigerant.

It is another object of the present invention to improve the efficiency of the heat exchanger particularly when a single refrigerant and an azeotropic or azeotropic-like mixed refrigerant are used.

[0013]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a pass number determining means for determining a pass number based on an output value from a detecting means for substantially detecting a refrigerant flow rate. Path switching means for switching to the number of paths.

Thus, when the flow rate of the refrigerant is small, the number of passes is reduced, thereby increasing the flow rate in the pipe of each pass, thereby improving the heat transfer coefficient, thereby improving the efficiency of the heat exchanger.

Further, a single refrigerant (R22) has conventionally been used due to the social background of environmental problems such as depletion of the ozone layer. However, as an alternative refrigerant candidate, for example, R32 / R125 (H32) in hydrofluorocarbon (HFC) has been used. 50/50
wt%) (hereinafter referred to as R410A) or propane (R290) in hydrocarbon (HC), the refrigerant density at the same cycle point is higher in these cycles than in the conventional R22, and therefore, It has the feature that the flow velocity is reduced. Therefore, by reducing the number of passes, the heat transfer coefficient is improved, and the efficiency of the heat exchanger is improved. In particular, R410A and propane (R29
0) is effective.

[0016]

DETAILED DESCRIPTION OF THE INVENTION As shown in FIG. 1, the invention according to claim 1 comprises a compressor 2 having a variable capacity, heat exchangers 4 and 6, and
A refrigeration cycle system having two or more paths (see FIG. 2) in at least one of the heat exchangers 4 and 6 and sequentially connecting the pressure reducing section 5 with a pipe, as shown in FIG. Detecting means 31 for substantially detecting a flowing refrigerant flow rate;
When the refrigerant flow rate detected by the detection means 31 is smaller than a predetermined value, the number of paths in the heat exchanger 4 is determined to be small, and the number of paths is determined based on a signal from the number of paths. By having the path switching means 33 for switching the number, the heat transfer coefficient in the heat exchanger 4 increases,
Heat exchanger efficiency is improved.

According to a second aspect of the present invention, a heat exchanger is provided in which the detecting means 31 of the first aspect is replaced with a refrigerant flow rate detecting means 41 for detecting a flow rate of a refrigerant flowing through a path as shown in FIG. The heat transfer coefficient in 4 increases, and the heat exchanger efficiency improves.

According to a third aspect of the present invention, there is provided a heat exchanger wherein the detecting means 31 according to the first aspect is an operating frequency detecting means 51 for detecting an operating frequency of a compressor as shown in FIG. The heat transfer coefficient in 4 increases, and the heat exchanger efficiency improves.

According to a fourth aspect of the present invention, the detecting means 31 according to the first aspect is replaced with a load detecting means 61 for detecting a load in the heat exchanger 4 as shown in FIG. The heat transfer coefficient in 4 increases, and the heat exchanger efficiency improves.

The invention according to claim 5 is the invention according to claims 1-4.
7, an operation mode determining unit 71 for detecting an operation mode of the heat exchanger 4 is provided as shown in FIG. 7, and the number of passes is appropriately determined based on the operation mode detected by the operation mode determining unit 71. By having the pass number correcting means 72 for correcting the value to a suitable value, the heat transfer coefficient in the heat exchanger 4 is increased, and the heat exchanger efficiency is improved.

The invention according to claim 6 is the invention according to claims 1 to 5.
In the embodiment described in the above, the refrigerant is hydrofluorocarbon (HFC) or hydrocarbane (HFC).
By using C) as a main component, the heat transfer coefficient in the heat exchanger 4 is increased and the heat exchanger efficiency is further improved as compared with the R22 system conventionally used in a refrigeration cycle device represented by an air conditioner. .

The invention according to claim 7 is the invention according to claims 1 to 6.
In the embodiment described in the above, the path switching means 33, 4
By using a movable valve as 3, 53, 63, the number of passes can be reduced.

[0023]

An embodiment will be described below with reference to the drawings.

In FIG. 1, 1 is a refrigeration cycle system, 2 is a compressor, 3 is a four-way valve, 4 is an outdoor heat exchanger, 5 is a decompression unit, 6 is an indoor heat exchanger, and 7 is an accumulator.

During the cooling operation of the refrigeration cycle system 1, as shown by the solid arrows, the high-temperature and high-pressure refrigerant gas discharged from the compressor 2 passes through the four-way valve 3 and forms an outdoor heat exchanger 4 forming a condenser (radiator). Into a liquid phase due to condensation (radiation). The refrigerant in the liquid phase flows into the indoor heat exchanger 6 forming an evaporator (heat absorber) through the decompression unit 5, and becomes a gas phase by evaporation (heat absorption). The gaseous refrigerant gas flows into the compressor 2 again through the four-way valve 3 and the accumulator 7. The number of passes in the outdoor heat exchanger 4 is controlled based on the refrigerant flow rate, which is an output value from the detection unit 31 that substantially detects the flow rate of the refrigerant flowing through the paths. During the heating operation, the four-way valve 3 is switched as shown by the dotted arrow, the indoor heat exchanger 6 becomes a condenser (radiator), and the outdoor heat exchanger 4 becomes an evaporator (heat absorber).

In the indoor heat exchanger 6 as well, the number of passes in the heat exchanger can be controlled based on the detection means 31.

Next, the outdoor heat exchanger 4 inlet X shown in FIG.
2 to the inside of the outdoor heat exchanger 4 and the outlet Y of the outdoor heat exchanger 4 will be described with reference to FIG. Here, as an example, 2
A path was used.

During normal cooling operation, as shown by the solid line,
It branches into two paths at the inlet branch point 21 of the heat exchanger.
After passing through the heat exchanger, one passes from the valve connection a through the valve 22 to b, and the other directly passes from the valve connection d through the valve to c, and after passing through the heat exchanger. , Exit junction 23
To join.

In the operation for reducing the number of passes in the heat exchanger, as shown by the dotted line of the valve 22, the gas does not flow into the valve connection d but passes through the valve connections a to c.

Next, an embodiment of the valve will be described with reference to FIG. Reference numeral 31 denotes a detecting unit, 32 denotes a path number determining unit, and 33 denotes a path switching unit.

The detection means 31 substantially detects the flow rate of the refrigerant flowing through the path. Regarding the detection means 31, any means can be used as long as the flow rate of the refrigerant can be substantially detected.

Here, the determination of the number of paths will be described. When the refrigerant flow rate is small, the refrigerant flow rate in the heat exchanger is small,
The heat transfer coefficient decreases. Therefore, if the number of passes is reduced at this time, the flow velocity in the pipe increases, and the heat transfer coefficient increases. As a result, the amount of heat exchange increases, and an improvement in capacity can be expected.

For the above reason, the pass number determining means 32 determines the number of passes as usual, for example, two passes, when the refrigerant flow rate, which is the output value from the detecting means 31, is equal to or more than a certain value α. When the refrigerant flow rate, which is the output value from the refrigerant flow rate detecting means 31, is smaller than the fixed value α, the number of passes is reduced, for example, one pass is determined.

The path switching means 33 performs path switching based on the output value from the path number determining means 32.

The path switching means 33 may be any means such as a manual ball valve and a solenoid valve.

Next, another embodiment of the valve will be described with reference to FIG. 41 is a refrigerant flow rate detecting means, 42 is a pass number determining means, and 43 is a path switching means.

The refrigerant flow rate detecting means 41 detects the flow rate of the refrigerant flowing through the path. When the refrigerant flow rate, which is the output value from the refrigerant flow rate detecting means 41, is equal to or larger than the fixed value β, the number of passes determining means 42 determines the number of passes as usual, for example, to two passes. When the refrigerant flow rate, which is the output value from the refrigerant flow rate detecting means 41, is smaller than the fixed value β, the number of passes is reduced, for example, one pass is determined.

The path switching means 43 performs path switching based on the output value from the path number determining means 42.

The path switching means 43 may be any means such as a manual ball valve and a solenoid valve.

In this embodiment, since the flow rate of the refrigerant is directly detected, the control can be performed with extremely high precision.

Next, another embodiment of the valve will be described with reference to FIG. 51 is an operating frequency detecting means, 52 is a path number determining means, and 53 is a path switching means.

The operating frequency detecting means 51 detects the operating frequency of the compressor 2. The number-of-passes determining means 52 determines the number of paths based on the operating frequency which is an output value from the operating frequency detecting means 51.

When the operating frequency is low, the flow rate of the refrigerant is expected to be small. Therefore, when the operating frequency is equal to or higher than the fixed value γ, the number of passes is determined as usual, for example, to two passes. When the operating frequency is smaller than the fixed value γ, the number of passes is reduced, for example, one pass is determined. Note that the constant value γ
Is determined in advance by experiments or the like so as to be optimal.

The path switching means 53 switches paths based on the output value from the path number determining means 52.

The path switching means 53 may be any means such as a manual ball valve and a solenoid valve.

In this embodiment, since the refrigerant flow rate is predicted by detecting the frequency, the control accuracy does not correspond one-to-one, but cost reduction can be expected.

Next, another embodiment of the valve will be described with reference to FIG. 61 is a load detecting means, 62 is a path number determining means, and 63 is a path switching means.

The load detecting means 61 detects a load. The means for detecting the load is not limited, but two examples are shown here.

As a first example, in an air conditioner, the air conditioner detects the temperature set by a user using a remote controller or the like, or detects the temperature controlled by the air conditioner during automatic operation. Detects the target temperature for control.

The room temperature is detected based on the thermistor installed in the room or the suction temperature.

Then, the temperature difference between the indoor target temperature and the indoor temperature is calculated, and when the temperature difference is large, the load is predicted to be large, and when the temperature difference is small, the load is predicted to be small.

As a second example, in an air conditioner, when the outside air temperature is detected, the load is small when the outside air temperature during heating is high or when the outside air temperature during cooling is low, and when the outside air temperature during heating is low, Alternatively, when the outside air temperature during cooling is high, it is predicted that the load is large.

As a third example, there is a combination of the first example and the second example. That is, when the outside temperature during heating is low and the difference between the indoor target temperature and the room temperature is large, the load is large. When the outside temperature during heating is high and the difference between the room target temperature and the room temperature is small, the load is large. Shall be small.

The number of paths determining means 62 determines the number of paths based on the load which is the output value from the load detecting means 61.

When the load is small, it can be expected that the flow rate of the refrigerant is small. Therefore, when the load is large, the number of paths is determined as usual, for example, two paths. When the load is small, the number of paths is reduced, for example, one path is determined.

The path switching means 63 performs path switching based on the output value from the path number determining means 62.

The path switching means 63 may be any means such as a manual ball valve and a solenoid valve.

Next, another embodiment of the valve will be described with reference to FIG. Reference numeral 71 denotes an operation mode determining unit, and reference numeral 72 denotes a pass number correcting unit.

In the heat exchanger, the efficiency of the air conditioner is also different in the evaporation process and the condensation process because the pressure loss differs for the same refrigerant flow rate. Therefore, it is better to change the threshold value of the refrigerant flow rate for switching the number of passes according to the operation mode of the heat exchanger in the evaporation process or the condensation process.

Therefore, the operation mode determination means 71 determines whether the operation mode of the heat exchanger is a condensation process or an evaporation process.

The number-of-paths correcting means 72 corrects the number of paths based on the number of paths, which is the output value from the number-of-paths determining means 32, and the operation mode, which is the output value from the operation-mode determining means 71.

Here, the pass number correcting means 72 will be described in detail. FIG. 8 shows the relationship between the refrigerant flow rate in the heat exchanger tube and the heat transfer coefficient.

When the number of passes is reduced, the flow rate of refrigerant in the pipe increases, so that the flow velocity per unit area increases and the heat transfer coefficient increases.

FIG. 9 shows the relationship between the refrigerant flow rate and the pressure loss in the heat exchanger tube in the evaporation process by a solid line, and in the condensation process by a dotted line.

In the condensation process, the increase in the pressure loss due to the increase in the flow rate of the refrigerant is small. On the other hand, in the evaporation process, when the flow rate of the refrigerant increases, the pressure loss increases significantly due to the expansion of the refrigerant particularly in the heat exchanger outlet path.

FIG. 10 shows the relationship between the refrigerant flow rate in the heat exchanger tube and the coefficient of performance (hereinafter referred to as COP) of the refrigeration cycle in the evaporation process by a solid line and in the condensation process by the dotted line.

As shown in FIG. 10 from FIGS. 8 and 9, the COP increases as the refrigerant flow rate increases in the condensation process as shown in FIG. In the evaporation process, the COP decreases as the pressure loss increases at a certain value.

From the above, when the refrigerant flow rate becomes equal to or more than a certain value in the evaporation process, the COP is improved by increasing the number of passes and decreasing the refrigerant flow rate.

Therefore, in this embodiment, when the output value from the operation mode determining means 71 is in the process of evaporating, it is better to lower the threshold value for switching the path.

Next, still another embodiment will be described. Conventionally, a single refrigerant (R22) has been used. However, as alternative refrigerant candidates, a single refrigerant having a small temperature gradient of the air temperature in a refrigeration cycle, or an azeotropic refrigerant such as R32 in hydrofluorocarbon (HFC) / R125 (5
0/50 wt%) (hereinafter referred to as R410A) or propane (R29A) in hydrocarbon (HC).
0) is used. In these cycles, the refrigerant density at the same cycle point is higher than that of the conventional R22, and thus the flow velocity is lower.

That is, when requesting the same ability, R
In 410A, the pressure loss in the heat exchanger and the pipe is reduced to about 70% of R22 as compared with R22.

From this fact, by using R410A, propane (R290) or the like as the refrigerant, the heat transfer coefficient is improved and the heat exchanger efficiency is improved.

Next, an embodiment of the path switching means will be described with reference to FIGS. Three examples of movable valves are given as path switching means.

A first example is a rotary type. As shown in FIG. 11, the paths a, b, c, and d are provided every 90 degrees around the valve, and the internal path of the valve includes a path passing through the center and two paths symmetrical about the center, a and b; Connect c and d. To make one pass, switching is performed as shown in FIG. 12, and the valve connection portions a and c are connected. Valve connections b and d are closed.

The second example is also of the rotary type. As shown in FIG. 13, the valve connection portions b and c are connected to the valve connection portion a.
And a line connecting to the center of the valve is provided symmetrically. The valve connection d is provided at an arbitrary position between the valve connections a and c. During normal operation, valve connections a and b are connected, and c and d are connected. To make one pass, the valve connections a and c are connected as shown in FIG. 14, and the valve connections b and d are closed. This has the advantage that the number of passes in the valve can be reduced and processing is easier than in the first example.

A third example is a direct-acting type. As shown in FIG. 15, the valve connection portions a and b, and c and d are connected. To make one pass, the valve body is shifted sideways as shown in FIG. 16, the valve connections a and c are connected, and the valve connections b and d are closed.

As described above, for example, when the temperature of the room becomes stable from the start-up under the heating operation of the air conditioner, the heating load is reduced and the operating frequency of the compressor is reduced. The ratio of this environment to the total operating hours per year is very large. Therefore, when considering the annual electricity bill, the ratio occupied by low-frequency operation is large. Thus, by using this control, it is possible to save about 5% of the annual electricity bill.

Further, hydrofluorocarbon (HF)
By using refrigerants of C) and hydrocarbons (HC), the value of ozone depletion potential (ODP) is 0 and the value of global warming potential (GWP) is large for hydrofluorocarbon (HFC) (H
C) is very close to zero. Therefore, environmental problems can be overcome.

Further, in the above-mentioned control device, by using a single or azeotropic or azeotrope-like mixed refrigerant among the hydrofluorocarbon (HFC) and the hydrocarbon (HC) as the refrigerant, the heat exchanger efficiency is further improved. Therefore, the refrigeration cycle efficiency can be improved, and as a result, the power consumption can be reduced.

[0080]

As described above, according to the present invention, the efficiency of the heat exchanger can be improved when the flow rate of the refrigerant is small by switching the number of passes of the heat exchanger. Thereby, by reducing the power consumption at the time of heating low load,
It is possible to reduce the annual electricity bill for air conditioners.

Further, also in the refrigerant mainly containing hydrofluorocarbon (HFC) or hydrocarbon (HC) which is a candidate for R22 as a substitute refrigerant, the heat transfer coefficient is improved and the heat exchanger efficiency can be improved. .

Further, by using the movable valve, the number of passes of the valve can be easily switched, and the number of parts and man-hours can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a refrigeration cycle control device according to an embodiment of the present invention.

FIG. 2 is a path diagram of the heat exchanger in the embodiment.

FIG. 3 is a control block diagram of Embodiment 1 of the valve of the heat exchanger in the embodiment of the present invention.

FIG. 4 is a control block diagram of Embodiment 2 of the valve of the heat exchanger according to the embodiment of the present invention.

FIG. 5 is a control block diagram of Embodiment 3 of the valve of the heat exchanger in the embodiment of the present invention.

FIG. 6 is a control block diagram of Embodiment 4 of the valve of the heat exchanger in the embodiment of the present invention.

FIG. 7 is a control block diagram of Embodiment 5 of the valve of the heat exchanger in the embodiment of the present invention.

FIG. 8 is a diagram showing a relationship between a refrigerant flow rate and a heat transfer coefficient in a heat exchanger tube.

FIG. 9 is a diagram showing a relationship between a refrigerant flow rate and a pressure loss in a heat exchanger tube.

FIG. 10 is a diagram showing a relationship between a refrigerant flow rate in a heat exchanger tube and a coefficient of performance COP of a refrigeration cycle.

FIG. 11 is a diagram showing two paths of a valve of the first example for controlling the path of the heat exchanger in the embodiment.

FIG. 12 is a view showing one path of a valve of the first example for controlling the path of the heat exchanger in the embodiment.

FIG. 13 is a view showing two paths of a valve of a second example for controlling the path of the heat exchanger in the embodiment.

FIG. 14 is a diagram showing one path of a second example valve for controlling the path of the heat exchanger in the embodiment.

FIG. 15 is a diagram showing two paths of a valve of a third example for controlling the path of the heat exchanger in the embodiment.

FIG. 16 is a diagram showing one path of a valve of a third example for controlling the path of the heat exchanger in the embodiment.

FIG. 17 is a path diagram of a conventional heat exchanger.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Refrigeration cycle system 2 Compressor 3,83 Four-way valve 4 Outdoor heat exchanger 5 Decompression part 6 Indoor heat exchanger 7 Accumulator 21 Heat exchanger entrance junction 22 Valve 23 Heat exchanger exit junction 31 Detecting means 32,42, 52, 62 pass number determining means 33, 43, 53, 63, 73 path switching means 41 refrigerant flow detecting means 51 operating frequency detecting means 61 load detecting means 71 operating mode determining means 72 pass number correcting means 81 heat exchanger 82 branch pipe 84 refrigerant pipe

Claims (7)

[Claims] 1. A compressor having a variable capacity, two or more heat exchangers, a refrigerant exchanging heat with these heat exchangers and a decompression unit, and at least one of the heat exchangers has at least one heat exchanger.
A refrigeration cycle system having a path for flowing the above-described refrigerant, and connecting these in sequence with pipes, a detecting means for substantially detecting a flow rate of the refrigerant flowing through the path, and a refrigerant flow rate detected by the detecting means When the number of passes is smaller than a predetermined value, the number of passes in the heat exchanger is determined to be reduced, and the path switching means that switches the number of passes based on a signal from the number of passes determining means. A refrigeration cycle control device characterized by the above-mentioned. 2. The method according to claim 1, wherein the detecting means is a refrigerant flow rate detecting means for detecting a flow rate of the refrigerant flowing through the path.
A refrigeration cycle control device according to the above. 3. The operating frequency detecting means according to claim 1, wherein said operating means detects an operating frequency of said compressor.
A refrigeration cycle control device according to the above. 4. The refrigeration cycle control device according to claim 1, wherein the detection means according to claim 1 is load detection means for detecting a load in the heat exchanger. 5. The refrigeration cycle control device includes an operation mode determination unit that detects an operation mode of the heat exchanger, and the number of passes in the heat exchanger is adjusted according to the operation mode detected by the operation mode determination unit. The refrigeration cycle control device according to any one of claims 1 to 4, further comprising pass number correction means for correcting the number of passes. 6. The refrigeration cycle control device according to claim 1, wherein a hydrofluorocarbon (HFC) or a hydrocarbon (HC) is used as a main component of the refrigerant. 7. The refrigeration cycle control device according to claim 1, wherein a movable valve is used as the path switching means.