JPH11281172A - Chiller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize energy saving by varying the rotational speed of a compressor based on the outer air temperature for determining the refrigeration load and the suction side refrigerant temperature of a compressor thereby determining the refrigeration load accurately and reducing power consumption. SOLUTION: When the difference between the outer air temperature and the suction side refrigerant temperature of a compressor 11 is 21 deg.C or above, refrigeration load is low and power consumption is low even if the compressor 11 is rotated at a high speed. A controller 19 controls the operating frequency being outputted from an inverter 12 to the compressor 11 such that the compressor 11 is rotated at a high speed. When the temperature difference is 10 deg.C or below, refrigeration load is high and power is consumed excessively if the compressor 11 is rotated at high speed. The controller 19 controls the operating frequency being outputted from the inverter 12 to the compressor 11 such that the compressor is rotated at an intermediate or low speed thus reducing power consumption. When the temperature difference is between 10-21 deg.C, the rotational frequency is controlled to rotate the compressor at an intermediate speed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a refrigeration system for reducing power consumption.

[0002]

2. Description of the Related Art Generally, showcases, commercial refrigerators,
As a vending machine or the like, a refrigeration apparatus in which a compressor, a condenser, a capillary tube, and an evaporator are connected by a refrigerant tube is known.

[0003]

In this type of refrigerating apparatus, there is a refrigerating apparatus in which the rotational speed of a compressor is changed according to a refrigerating load. The refrigeration load is determined based on a detection value of a temperature sensor that is installed in a refrigerator such as a showcase and detects the temperature in the refrigerator.

[0004] Therefore, even if the products are of the same quantity, the refrigeration load differs depending on whether or not they are arranged near the temperature sensor. For example, if the product is arranged at a position distant from the temperature sensor and it is determined that the refrigeration load is small in spite of the fact that the actual refrigeration load is large, if the compressor is rotated at a high speed, the electric power is excessively increased. May consume.

An object of the present invention has been made in view of the above circumstances, and an object of the present invention is to provide a refrigeration apparatus capable of reducing power consumption and realizing energy saving.

[0006]

According to the first aspect of the present invention,
In a refrigerating device including a variable-speed compressor, a condenser, a decompression device, and an evaporator, wherein the compressor is controlled by a control device, the control device can determine a refrigerating load,
The rotation speed of the compressor is changed based on the outside air temperature and the suction-side refrigerant temperature of the compressor.

According to a second aspect of the present invention, in the first aspect of the present invention, a storage device storing a plurality of types of operation modes is connected to the control device. The rotational speed of the compressor determined in accordance with the temperature difference with the suction side refrigerant temperature of the machine, based on the outside air temperature, is arranged for each temperature difference, the control device is The rotational speed of the compressor is selected from the above operation modes based on the outside air temperature and the suction-side refrigerant temperature of the compressor to change the rotational speed of the compressor.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the control device calculates a detected temperature at a predetermined time in a suction side refrigerant temperature of the compressor using a moving average method. Then, an average value is obtained, and this average value is used as the suction-side refrigerant temperature of the compressor.

The invention described in claim 1 or 2 has the following operation.

The control device changes the rotation speed of the compressor based on the outside air temperature and the suction-side refrigerant temperature of the compressor, which can determine the refrigeration load.
The refrigeration load can be determined more accurately than in the case where the rotation speed of the compressor is changed based on the temperature in the refrigerator housing the evaporator. As a result, the rotational speed of the compressor set corresponding to the refrigeration load becomes appropriate, and excessive consumption of electric power can be suppressed, so that power consumption can be reduced and energy saving can be realized.

The third aspect of the invention has the following operation.

Even if a showcase or the like accommodating the evaporator is frequently opened and closed and the refrigerating load fluctuates each time, the detected value of the refrigerant temperature on the suction side of the compressor is not used as it is, and the detected value is calculated by the moving average method. Since the value calculated in the above is the suction side refrigerant temperature, the rotation speed of the compressor determined based on the temperature difference between the suction side refrigerant temperature of the compressor and the outside air temperature does not frequently change,
Control stability can be realized.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

The refrigeration apparatus 10 shown in FIG. 1 is a refrigeration apparatus such as a showcase, a commercial refrigerator, a vending machine, and the like.
In the refrigeration system 10, reference numeral 11 denotes the inverter 1
2 shows a compressor whose rotation speed is adjusted.

A condenser 13 (condenser), a capillary tube 14 (decompression device) and an evaporator 15 (evaporator) are connected to the compressor 11 in a closed loop by using a refrigerant pipe 16, and a condenser fan 17 is connected to the condenser 13. The evaporator 15 is provided with an evaporator fan 18. The evaporator 15 is installed in a storage such as a showcase and cools the storage.

The inverter 12 adjusts the frequency of the current supplied to the electric motor of the compressor 11 to change the rotation speed of the compressor 11, and is controlled by the control device 19. This controller 19 has an outside air temperature sensor 20,
The suction-side refrigerant temperature sensor 21 and the storage device 22 are connected.

The outside air temperature sensor 20 detects the outside air temperature in a storage such as a showcase or the like, and outputs the detection signal to the control device 19.
Send to Further, the suction-side refrigerant temperature sensor 21 detects the temperature of the refrigerant gas sucked into the compressor 11, and the detection signal is transmitted to the control device 19.

The control device 19 includes a suction-side refrigerant temperature sensor 2
An average value is calculated using the moving average method from the detection values detected at a predetermined time (for example, 5 minutes) detected in step 1, and the average value is set as the suction side refrigerant temperature. That is, the control device 19 calculates an average of a plurality of (eg, three) adjacent detection values among the detection values A, B, C, D, E,... Detected by the suction-side refrigerant temperature sensor 21 at predetermined time intervals. Value α [= (A + B + C) /
3], β [= (B + C + D) / 3], γ [= (C + D +
E) / 3]... Are continuously calculated, and the average values α, β, γ
... are the suction-side refrigerant temperatures at each time point.

As shown in FIG. 4, the storage device 22 stores a plurality of types of operation modes (rapid operation mode, 1-saving operation mode,
2 saved operation mode and 3 saved operation mode). The three-saving operation mode is an operation mode with the least power consumption, the two-saving operation mode is an operation mode with the lowest power consumption next to the three-saving operation mode, and the one-saving operation mode is next to the two-saving operation mode. This is an operation mode with low power consumption. The rapid operation mode is an operation mode in which energy saving is ignored, and has the largest power consumption. These operation modes are provided to be selectable by a user of the refrigeration apparatus 10.

In each operation mode shown in FIG. 4, the rotation speed of the compressor 11 determined in accordance with the temperature difference ΔT between the outside air temperature and the suction-side refrigerant temperature of the compressor 11 is based on the outside air temperature.
These are arranged for each of the temperature differences ΔT.

That is, when the outside air temperature is in an extremely high temperature range (35 ° C.)
, For example, 40 ° C.), a high temperature region (25 to 34 ° C., for example, 30), a medium temperature region (10 to 24 ° C., for example, 15 ° C.), and a low temperature region (領域 9 ° C., for example, 5 ° C.). The temperature difference ΔT from the temperature is calculated.

In the first operation mode, the temperature difference ΔT
Is higher than 21 ° C., the refrigeration load is small and the compressor 11
Power consumption is small even when the compressor is rotated at high speed.
To rotate the compressor 11
The operating frequency output to the controller is controlled by the controller 19. When the temperature difference ΔT is equal to or less than 10 ° C., the refrigeration load is large, and if the compressor 11 is rotated at a high speed, the power consumption becomes excessive. The operating frequency output to 11 is controlled by the control device 19 to reduce power consumption. Further, the temperature difference ΔT is 10 to 21 ° C.
In the case of, the refrigeration load is medium, and in order to prevent the compressor 11 from rotating at a high speed by rotating the compressor 11 at a high speed, the output from the inverter 12 to the compressor 11 is set so that the compressor 11 is rotated at a medium speed. The rotation frequency to be controlled is controlled by the control device 19 to reduce power consumption.

In the three-save operation mode, reduction of power consumption is given the highest priority. Therefore, in all regions of the outside air temperature, the output from the inverter 12 to the compressor 11 is set so that the compressor 11 rotates at a low speed. The operating frequency to be performed is controlled by the control device 19 to reduce power consumption.

For the same reason, in the case of the two-save operation mode, the compressor 1 does not operate in each region except the low outside air temperature region.
The operating frequency output from the inverter 12 to the compressor 11 is controlled by the control device 19 so that 1 rotates at the medium speed, thereby reducing power consumption. However, when the outside air temperature is in a low temperature range, the refrigeration capacity is hardly needed, and the operating frequency output from the inverter 12 to the compressor 11 is controlled by the controller 19 so that the compressor 11 rotates at low speed. As a result, power consumption is reduced.

Further, in the rapid operation mode, priority is given to rapid cooling ignoring the reduction in power consumption, so that the compressor 11 rotates at a high speed in an ultra-high temperature region and a high temperature region of the outside air temperature. The operating frequency output from the inverter 12 to the compressor 11 is controlled by the control device 19. When the outside air temperature is in the low temperature range and the medium temperature range, the refrigeration capacity is not so much or almost not necessary.
Compressor 1 from inverter 12 so that
The operating frequency output to 1 is controlled by the control device 19 to reduce power consumption.

The setting of the number of revolutions of the compressor 11 based on a concrete detection value of the outside air temperature and the temperature of the refrigerant on the suction side of the compressor 11
One example shown for each operation mode is shown in FIG.

By the way, as shown in FIG. 2, when the inside of the refrigerator such as a showcase is cooled after the operation of the refrigeration system 10 is started, and reaches a set temperature t1 (thermo-off temperature), It enters the operation standby state (thermo-off), gradually rises due to heat leak, and when it reaches the set temperature t2 (thermo-on temperature), it enters the operation state again and falls. Normally, the above-described control is repeated by the control device 19, and the inside of the refrigerator such as a showcase is adjusted to a temperature having a substantially constant width. In FIG. 2, a solid line A indicates a case where the compressor 11 is rotating at high speed, a solid line B indicates a case where the compressor 11 is rotating at medium speed, and a solid line C indicates a case where the compressor 11 is rotating at low speed.

The control device 19 controls the operation frequency output from the inverter 12 to the compressor 11 to change the rotation speed of the compressor 11 based on the operation mode selected by the user. At this time, the control device 19 determines the temperature difference (β) between the adjacent preceding and succeeding suction-side refrigerant temperatures (average values α, β, γ...) Continuously calculated by the moving average method from the detection values of the suction-side refrigerant temperature sensor 21. −α, γ−β,...) Are equal to or greater than the predetermined temperature difference, it is determined that the refrigeration load has changed. At this time, the control device 19 calculates a temperature difference ΔT between the outside air temperature detected by the outside air temperature sensor 20 and the last calculated suction side refrigerant temperature (for example, γ), and the operation mode shown in FIG. In the table, the rotation speed of the compressor 11 corresponding to the temperature difference ΔT is selected from the outside air temperature range to which the current outside air temperature detected by the outside air temperature sensor 20 belongs and the selected operation mode. The control device 19 changes the operating frequency output from the inverter 12 to the compressor 11 so as to rotate the compressor 11 at the selected rotation speed. Thus, the control device 19 determines the temperature difference ΔT between the outside air temperature and the suction side refrigerant temperature.
The rotation speed of the compressor 11 is changed based on the above.

For example, when the low-operation mode is selected by the user, if the outside air temperature is in the ultra-high temperature range, the refrigeration load is large at the beginning of the operation, and the temperature difference ΔT between the outside air temperature and the suction refrigerant temperature is reduced. Since the temperature is as small as 20 ° C., the controller 19 operates the compressor 11 at a medium speed to suppress an increase in power consumption, and when the refrigeration load is reduced, that is, the temperature difference ΔT between the outside air temperature and the suction refrigerant temperature is reduced. When the temperature reaches 25 ° C. or higher, the compressor 11 is rotated at a high speed. FIG. 3 shows a change in the internal temperature realized by this control.

Compressor 11 in the above-mentioned one-save operation mode
Is that the refrigerant pressures on the inlet side and the outlet side of the condenser 13 and the evaporator 15 are not the same at the beginning of the refrigerating apparatus 10, and the pressure balance is not maintained well. In the initial state of the refrigeration apparatus 10, the compressor 11 is rotated at a medium speed.
This is an affirmative response from the technical background that the compressor 11 should be rotated at a high speed when the pressure balance of the refrigerant flowing through the compressor is sufficiently ensured.

According to the above embodiment, the following effects and advantages can be obtained.

The temperature difference ΔT between the outside air temperature at which the refrigeration load can be determined and the temperature of the refrigerant on the suction side of the compressor 11 is determined by the control device 19.
, The rotational speed of the compressor 11 is changed on the basis of the temperature of the compressor 1 based on the internal temperature at which the refrigeration load can be determined.
The refrigeration load can be determined more accurately than in the case where the rotation speed is changed. As a result, the rotational speed of the compressor 11 set corresponding to the refrigeration load becomes appropriate, and excessive consumption of electric power can be suppressed, so that power consumption can be reduced and energy saving can be realized.

Even if the showcase or the like accommodating the evaporator 15 is frequently opened and closed and the refrigeration load fluctuates each time, the detected value of the suction-side refrigerant temperature of the compressor 11 is not used as it is, and the detected value is moved to the moving average. Α, β, γ
... is the suction-side refrigerant temperature of the compressor 11, the rotation speed of the compressor 11, which is determined based on the temperature difference ΔT between the suction-side refrigerant temperature of the compressor 11 and the outside air temperature, is not frequently changed. Stability can be ensured.

Although the present invention has been described based on one embodiment, the present invention is not limited to this. For example, the rotation speed of the compressor 11 is controlled by the inverter 12.
Has been described, but tapping may be used.

[0035]

As described above, according to the refrigeration system of the present invention, the rotation speed of the compressor is changed based on the temperature difference between the outside air temperature at which the refrigeration load can be determined and the temperature of the suction side refrigerant of the compressor. As a result, the refrigeration load can be accurately determined, and the power consumption can be reduced to realize energy saving.

[Brief description of the drawings]

FIG. 1 is a refrigerant circuit diagram showing an embodiment of a refrigeration apparatus according to the present invention.

FIG. 2 is a graph showing the relationship between the rotational speed of the compressor of FIG.

3 is a graph showing an example of a change over time of a rotation speed of a compressor and a temperature in a refrigerator when an outside air temperature is in an ultra-high temperature range in the 1-saving operation mode of FIG. 4;

FIG. 4 is a table showing an operation mode table stored in the storage device of FIG. 1;

FIG. 5 is a table of a specific example showing the number of revolutions of the compressor in each operation mode executed by the operation mode table of FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Refrigerator 11 Compressor 12 Inverter 13 Condenser (Condenser) 14 Capillary tube (Decompression device) 15 Evaporator (Evaporator) 19 Control device 20 Outside air temperature sensor 21 Suction side refrigerant temperature sensor 22 Storage device

Claims (3)

[Claims] 1. A refrigeration apparatus comprising a variable-speed compressor, a condenser, a decompression device, and an evaporator, wherein the compressor is controlled by a control device, wherein the control device can determine a refrigeration load. A refrigeration apparatus characterized by changing a rotation speed of the compressor based on an outside air temperature and a suction-side refrigerant temperature of the compressor. 2. A storage device in which a plurality of types of operation modes are stored is connected to the control device, wherein the operation mode is determined in accordance with a temperature difference between an outside air temperature and a suction-side refrigerant temperature of a compressor. The rotation speed of the compressor is arranged for each of the temperature differences on the basis of the outside air temperature, and the control device controls the outside air temperature and the suction-side refrigerant temperature of the compressor. 2. The refrigeration apparatus according to claim 1, wherein a rotation speed of the compressor is selected from the respective operation modes and the rotation speed of the compressor is changed. 3. The control device calculates an average value by calculating a detected temperature at a predetermined time at a suction side refrigerant temperature of the compressor using a moving average method, and calculates the average value on the suction side refrigerant temperature of the compressor. The refrigeration apparatus according to claim 1 or 2, wherein the temperature is a refrigerant temperature.