WO2021245792A1

WO2021245792A1 - Cooling device

Info

Publication number: WO2021245792A1
Application number: PCT/JP2020/021791
Authority: WO
Inventors: 歩江上; 英希大野
Original assignee: 三菱電機株式会社
Priority date: 2020-06-02
Filing date: 2020-06-02
Publication date: 2021-12-09
Also published as: JPWO2021245792A1

Abstract

This cooling device (100) comprises: an evaporator (41); a sensor (51, 52) that acquires a parameter indicating a heat exchange performance of the evaporator (41); a cleaning device (5) that cleans the evaporator (41); and a control device (10) that controls the cleaning device (5). The control device (10) is configured to activate the cleaning device (5) in cases where the value of the parameter indicates that the heat exchange performance of the evaporator (41) has dropped below a reference state.

Description

Cooling system

This disclosure relates to a cooling device.

Conventionally, a cooling device having a cleaning function is known. For example, in Japanese Patent Application Laid-Open No. 2008-0760330 (Patent Document 1), the heat exchange unit can be uniformly cleaned by rotating the injection nozzle with respect to the heat exchange unit without using a special driving means. A cleaning device for the unit cooler is disclosed.

Japanese Unexamined Patent Publication No. 2008-0760330

The above technology describes the structure for improving the cleaning effect, and there is room for improvement in optimizing the cleaning timing. Since the cooling function is stopped during cleaning, for example, in a method of performing cleaning at a fixed cycle or at a fixed time, if the cleaning frequency is too high, the temperature of the cooling target space may rise. Further, if the cleaning frequency is too low, dust and the like adhering to the heat exchange unit may not flow out and stay there, and the cooling capacity may decrease.

The purpose of this disclosure is to disclose a cooling device with an optimized cleaning frequency.

The cooling device of the present disclosure includes an evaporator, a sensor for acquiring parameters indicating the heat exchange performance of the evaporator, a cleaning device for cleaning the evaporator, and a control device for controlling the cleaning device. The control device is configured to activate the cleaning device if the value of the parameter indicates a heat exchange performance that is lower than the reference state.

According to the cooling device of the present disclosure, cleaning can be started at the optimum timing. By optimizing the cleaning timing, unnecessary cleaning can be eliminated and the original cooling capacity of the cooling device can be maintained.

It is a functional block diagram which shows the structure of the cooling apparatus 100 of this embodiment. It is a ph diagram which showed the refrigerating cycle in the case of performing a cooling operation in an environment which does not require cleaning. It is a ph diagram showing a refrigerating cycle when a cooling operation is performed for a certain period of time in a place where dust is likely to accumulate in an evaporator. It is a figure for demonstrating the sensor used for detecting the cleaning start timing. It is a figure which showed the change of the parameter TD when cleaning is not performed. It is a figure which showed the change of the parameter TD in the case of performing cleaning. It is a flowchart for demonstrating the control which performs the determination of the washing start. It is a flowchart for demonstrating the 1st modification of the control which determines the start of cleaning. It is a flowchart for demonstrating the 2nd modification of the control which determines the start of cleaning. It is a figure for demonstrating the modification of the method of determining the start of cleaning.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Hereinafter, a plurality of embodiments will be described, but it is planned from the beginning of the application to appropriately combine the configurations described in the respective embodiments. The same or corresponding parts in the drawings are designated by the same reference numerals and the description thereof will not be repeated. In the figure below, the relationship between the sizes of each component may differ from the actual one.

FIG. 1 is a functional block diagram showing the configuration of the cooling device 100 of the present embodiment. As shown in FIG. 1, the cooling device 100 includes a compressor 1, a condenser 2, an expansion valve 3, a unit cooler 4 (heat exchange unit), a cleaning device 5, a control device 10, and a remote controller. 20 and. A refrigerant is sealed in the cooling device 100. The refrigerant circulates in the order of the compressor 1, the condenser 2, the expansion valve 3, and the unit cooler 4.

The unit cooler 4 includes an evaporator 41, a fan 44, and a drain pan 45.
The unit cooler 4 incorporates a cleaning device 5 that defrosts and cleans the evaporator 41.

The cleaning device 5 includes a water supply source 30, an on-off valve 32, and a cleaning pipe 34. The cleaning pipe 34 is formed with a water supply port Win to which cleaning water is supplied and a plurality of nozzles Nz1 for injecting cleaning water. The fan 44 forms an airflow Wd that passes through the evaporator 41. The drain pan 45 receives water droplets from the evaporator 41. The water droplets that have fallen on the drain pan 45 are drained from a water pipe (not shown).

The on-off valve 32 is connected between the water supply source 30 and the water supply port Win. When the on-off valve 32 is opened, cleaning water is supplied from the water supply source 30 to the cleaning pipe 34, and automatic cleaning of the inside of the unit cooler 4 is started. When the on-off valve 32 is closed, the automatic cleaning is completed. The water supply source 30 includes a pump (not shown) that generates the water pressure required for injecting the washing water from the plurality of nozzles Nz1. The water supply port Win may be connected to a water faucet. The water supply source 30 does not have to include a pump.

The control device 10 controls the drive frequency of the compressor 1 to control the amount of refrigerant discharged by the compressor 1 per unit time. The control device 10 controls the opening degree of the expansion valve 3 so that the degree of superheat of the refrigerant flowing out of the evaporator 41 is within a desired range. The control device 10 controls the amount of air blown per unit time of the fan 44. The control device 10 controls the on-off valve 32. The remote controller 20 receives an operation from the user and transmits a signal indicating the operation to the control device 10. The control device 10 receives a signal from the remote controller 20 and controls the cooling device 100.

When the defrosting condition is satisfied, the control device 10 stops the compressor 1 and defrosts the evaporator 41 (off-cycle defrost) by blowing air from the fan 44. As the defrosting condition, for example, a condition that a certain time has passed since the previous defrosting operation can be mentioned. The defrosting method and defrosting conditions are not limited to the above, and may be performed by other methods.

The control device 10 includes a processing circuit 11, a memory 12, and an input / output unit 13. The processing circuit 11 may be dedicated hardware or a CPU (Central Processing Unit) that executes a program stored in the memory 12. When the processing circuit 11 is a CPU, the function of the control device 10 is realized by software. The software is described as a program and stored in the memory 12. The processing circuit 11 reads and executes the program stored in the memory 12. The memory 12 includes a non-volatile or volatile semiconductor memory (for example, RAM (Random Access Memory), ROM (Read Only Memory), flash memory, etc. The CPU is a central processing device, a processing device, a computing device, and the like. , Microprocessor, microcontroller, processor, or DSP (Digital Signal Processor).

FIG. 2 is a ph diagram showing a refrigeration cycle when a cooling operation is performed in an environment that does not require cleaning.

The refrigeration cycle C1 in the normal operation state is shown by a solid line, and the refrigeration cycle C2 in the frosted state after a lapse of time is shown by a broken line.

In the refrigeration cycle C1, the refrigerant circulates at the condensation pressure PH and the evaporation pressure PL1. On the other hand, in the refrigerating cycle C2 in the frosted state, since frost is attached to the evaporator 41, the air volume is lowered and the heat transfer coefficient is lowered. Therefore, in the refrigeration cycle C2, the evaporation temperature is lowered in order to maintain the temperature inside the refrigerator. Since the refrigerant in the evaporator 41 is in the two-phase region, the pressure decreases as the temperature decreases. Therefore, in the refrigeration cycle C2, the evaporation pressure drops from PL1 to PL2. As a result, the efficiency of the refrigeration cycle deteriorates, and the performance as a cooling device deteriorates.

Therefore, the conventional unit cooler is equipped with a defrosting operation function to prevent capacity deterioration due to frost formation. On the other hand, in a food factory or the like, dust or the like is accumulated on the evaporator 41, and the performance of the cooling device may not be restored only by executing the defrosting operation.

FIG. 3 is a ph diagram showing a refrigeration cycle when a cooling operation is performed for a certain period of time in a place where dust is likely to accumulate on the evaporator.

When the unit cooler is in a place where dust is likely to accumulate, it will frost from a non-frosted state and also adhere to the unit cooler, so that the evaporator 41 will be in a state of having dust and frost. .. In the refrigeration cycle C2 at this time, the evaporation pressure drops from PL1 to PL2 as in the case of FIG.

Even if the conventional defrosting operation is performed with dust and frost attached, the dust remains accumulated. Therefore, after the defrosting operation, the refrigeration cycle C3 in FIG. 3 is obtained, and the evaporation pressure becomes PL3. And it does not recover to PL1. Therefore, it is difficult to maintain the original performance of the cooling device only by performing the defrosting operation.

In order to prevent this decrease in cooling capacity, the dust adhering to the evaporator 41 is washed. The method of detecting the cleaning start timing will be described below.

FIG. 4 is a diagram for explaining a sensor used for detecting the cleaning start timing. As shown in FIG. 4, a sensor 52 for detecting the room temperature RT, which is the temperature of the air in the cooling target space, is provided. Further, a sensor 54 for detecting the evaporation temperature ET of the refrigerant is provided on the refrigerant inlet side of the evaporator 41, or a sensor 51 for detecting the evaporation pressure PL is provided at the refrigerant outlet of the evaporator 41.

In the present embodiment, the timing of starting cleaning is determined using the parameter TD. The parameter TD is calculated by the following equation (1).
TD = RT-ET ... (1)
Then, after defrosting, the parameter TD is calculated to determine the necessity of cleaning.

As shown in FIG. 4, there are two methods for measuring the evaporation temperature ET: a method of measuring by the temperature sensor 54 on the inlet side and a method of converting the evaporation temperature ET into the saturated gas temperature from the pressure sensor 51 on the outlet side. The room temperature RT may be measured by the temperature sensor 52, but a fixed value which is a target temperature may be adopted. The setting of the room temperature RT used for calculating the parameter TD is appropriately changed depending on the site environment. Hereinafter, the parameter TD will be described with reference to FIGS. 5 and 6.

FIG. 5 is a diagram showing changes in the parameter TD when cleaning is not performed. In FIG. 5, the time t0 to t1, t2 to t3, and t4 are the periods during which the cooling operation is executed, and the times t1 to t2 and t3 to t4 are the periods during which the defrosting operation is executed.

The waveform W1 is a waveform showing a change in the parameter TD at a place where dust is likely to accumulate on the surface of the evaporator 41. The waveform W2 is a waveform showing a change in the parameter TD at a place where dust does not accumulate on the surface of the evaporator 41.

In the waveform W2, the parameter TD returns to the initial setting value TD0 after defrosting, but in the waveform W1, the parameter TD is set even after defrosting because the dust is not removed even after defrosting and gradually accumulates. It will gradually increase.

That is, after defrosting, the parameter TD is measured for a certain period of time, and if it returns to the original value, it means that no dust has adhered. It is presumed that the performance of the cooler is deteriorated as in the refrigeration cycle C3 of 3.

FIG. 6 is a diagram showing changes in the parameter TD when cleaning is performed. In FIG. 6, times t10 to t11 and t12 to t13 are periods during which the cooling operation is executed, and times t11 to t12 and t13 to t14 are periods during which the defrosting operation is executed.

If the cooling operation is continued for a certain period of time, the defrosting operation will start. The parameter TD increases as the cooling operation is continued. In the cooling-defrosting operation at the site where dust is likely to accumulate, when the defrosting is completed and the cooling operation is restarted, the cooling operation is started in a state where the TD is larger than the initial setting value TD0.

The waveform W11 has the same waveform as the waveform W1 in FIG. 5 because the cleaning start using the parameter TD is not executed.

The waveform W12 is a waveform when the cleaning start determination using the parameter TD is executed. In the waveform W12, the parameter TD is measured for a certain period of time Δt after the defrosting operation is completed. At that time, if the parameter TD does not exceed the threshold value TDth (time t12 to t12A), cleaning is not performed, but if the parameter TD exceeds the threshold value TDth (time t14), cleaning is performed. (Times t14 to t15), the parameter TD returns to the initial setting value TD0, and after the time t15, the cooling operation in which the cooling performance is restored is restarted.

FIG. 7 is a flowchart for explaining the control for determining the start of cleaning. The process of the flowchart of FIG. 7 is repeatedly executed for a certain period of time when the defrosting operation is completed.

In step S1, the control device 10 calculates the parameter TD by the above-mentioned equation (1), and determines whether or not the parameter TD exceeds the threshold value TDth.

If the parameter TD does not exceed the threshold value TDth (NO in S1), the cleaning operation is not executed and the cooling operation is returned.

On the other hand, when the parameter TD exceeds the threshold value TDth (YES in S1), the control device 10 opens the on-off valve 32 and starts the cleaning operation of the evaporator 41 by the cleaning device 5 in step S2. Then, when a certain period of time elapses and the cleaning is completed in step S3, the cooling operation is resumed.

(Explanation of modification)
FIG. 8 is a flowchart for explaining a first modification of the control for determining the start of cleaning. Steps S11 to S13 of FIG. 8 are the same processes as steps S1 to S3 of FIG. 7, respectively.

In the process shown in FIG. 8, after the cleaning in step S13 is completed, the parameter TD is measured again in step S14, and when the parameter TD does not return to the threshold value TDth or less (NO in S14), in steps S12 and S13 again. Perform cleaning. In this way, the control device 10 repeatedly performs cleaning until the parameter TD becomes equal to or less than the threshold value TDth.

In the modified example shown in FIG. 8, if the threshold value TDth is set appropriately, the cooling capacity of the cooling device can be reliably returned to a state close to the initial state.

FIG. 9 is a flowchart for explaining a second modification of the control for determining the start of cleaning.

In step S21, the control device 10 calculates the parameter TD according to the above equation (1), counts the number of consecutive times that the parameter TD exceeds the threshold value TDth, and determines whether or not the number of times has reached X or more. Judge.

If the number of consecutive times the parameter TD exceeds the threshold value TDth is less than X times (NO in S21), the cleaning operation is not executed and the cooling operation is returned.

On the other hand, when the number of times the parameter TD exceeds the threshold value TDth is X or more consecutively (YES in S1), the control device 10 executes the cleaning process in steps S22 and S23. Steps S22 and S23 of FIG. 9 are the same processes as steps S2 and S3 of FIG. 7, respectively.

In the process shown in FIG. 9, the control device 10 measures the parameter TD again in step S24 after the cleaning in step S23 is completed, and compares it with the threshold value TDth. When the parameter TD exceeds the threshold value TDth (YES in S24), in step S25, the control device 10 determines whether or not the number of consecutive times determined as TD> TDth is Y or more. ..

If the number of consecutive times for which TD> TDth is determined is not Y or more (NO in S25), the control device 10 performs cleaning again in steps S22 and S23. In this way, the control device 10 repeatedly performs cleaning until the parameter TD becomes equal to or less than the threshold value TDth. Therefore, even in the modified example shown in FIG. 9, the cooling capacity of the cooling device can be reliably returned to the initial state.

However, when the number of consecutive times when TD> TDth is determined is Y or more (YES in S25), the control device 10 may have a failure other than dirt adhesion, so the display unit of the remote controller 20 or the like is used. And raise an alarm to the user.

The user can confirm from this alarm whether defrosting or cleaning is not performed properly and there is no abnormality in the unit.

FIG. 10 is a diagram for explaining a modified example of the method for determining the start of cleaning. In FIGS. 5 to 9, the parameter TD is used to determine the start of cleaning, but it may be detected that dirt has adhered to the evaporator 41 by another method.

As shown in FIG. 10, the cooling device 100A of the modified example includes a fan 44 for supplying air in the cooling target space to the evaporator 41. The parameter used in the cooling device 100A is the flow rate F of air passing through the ventilation gap formed on the surface of the evaporator 41. The air flow rate F is detected by the air volume sensor 55. The control device 10 is configured to operate the cleaning device 5 when the flow rate F becomes smaller than the threshold value Fth.

When dust or the like adheres to the heat exchange fins of the evaporator 41, the amount of air passing through the evaporator 41 decreases. Therefore, as shown in FIG. 10, when the air volume sensor 55 is arranged in the ventilation path of the unit cooler 4 and the fan 44 is rotated at a predetermined rotation speed, the air volume is reduced from the determination threshold value as a trigger. The control device 10 may start cleaning.

(summary)
The above embodiments will be summarized again with reference to the drawings.

As shown in FIGS. 1 and 7, the cooling device 100 of the present disclosure includes an evaporator 41,

sensors

51 and 52 for acquiring parameters indicating the heat exchange performance of the evaporator 41, and a cleaning device for cleaning the evaporator 41. 5 and a control device 10 for controlling the cleaning device 5. The control device 10 is configured to operate the cleaning device 5 when the value of the parameter shows a heat exchange performance lower than the reference state. As a result, cleaning can be started at the optimum timing. By optimizing the cleaning timing, unnecessary cleaning can be eliminated and the original cooling capacity of the unit cooler can be maintained. In addition, since the frequency of stopping the cooling operation is reduced, it is possible to realize a cooling device having excellent energy saving.

Preferably, as shown in FIGS. 6 and 7, the control device 10 determines the value of the parameter acquired by using the

sensor

51 or 52 after performing the defrosting operation for removing the frost adhering to the evaporator 41. When the heat exchange performance of the evaporator 41 is lower than the reference state, the cleaning device 5 is configured to operate.

Preferably, as shown in FIG. 6, the parameter TD is the difference between the temperature RT of the air in the cooling target space where the refrigerant exchanges heat in the evaporator 41 and the evaporation temperature ET of the refrigerant in the evaporator 41. The control device is configured to operate the cleaning device 5 when the parameter TD becomes larger than the threshold value TDth.

More preferably, as shown in FIG. 4, the sensor includes a sensor 52 for measuring the temperature RT of air, a sensor 54 for measuring the temperature ET of the refrigerant passing through the evaporator 41, or a sensor 51 for measuring the pressure PL. ..

Preferably, as shown in FIG. 10, the cooling device 100A further includes a fan 44 for supplying air in the cooling target space to the evaporator 41. The parameter used in the cooling device 100A is the flow rate F of air passing through the ventilation gap formed on the surface of the evaporator 41. The air flow rate F is detected by the air volume sensor 55. The control device 10 is configured to operate the cleaning device 5 when the flow rate F becomes smaller than the threshold value Fth. In this case, in FIGS. 7, 8 and 9, the air volume F is used as the parameter instead of the parameter TD, and the threshold value Fth is used instead of the threshold value TDth.

Preferably, as shown in FIG. 8, the control device 10 is configured to repeatedly operate the cleaning device 5 until the heat exchange performance of the evaporator 41 increases from the reference state. By doing so, the cooling capacity of the cooling device can be reliably restored by cleaning.

More preferably, as shown in FIG. 9, the control device 10 uses the cleaning device 5 in a state where the heat exchange performance of the evaporator 41 is once lowered from the reference state and then the heat exchange performance remains lower than the reference state. When the number of times of repeated operation is equal to or greater than the determination value Y, a warning is given to the user. By doing so, if the cooling capacity is not restored by automatic cleaning, the user can inspect and repair the cooling device.

The embodiments disclosed this time should be considered to be exemplary in all respects and not restrictive. The scope of the present disclosure is set forth by the scope of claims rather than the description of the embodiments described above, and is intended to include all modifications within the meaning and scope of the claims.

1 Compressor, 2 Condenser, 3 Expansion valve, 4 Unit cooler, 5 Cleaning device, 10 Control device, 11 Processing circuit, 12 Memory, 13 Input / output section, 20 Remote controller, 30 Water supply source, 32 On-off valve, 34 Cleaning Piping, 41 evaporator, 44 fan, 45 drain pan, 51 pressure sensor, 52, 54 temperature sensor, 55 air volume sensor, 100, 100A cooling device, Nz1 nozzle.

Claims

With an evaporator,
A sensor that acquires parameters indicating the heat exchange performance of the evaporator, and
A cleaning device for cleaning the evaporator and
A control device for controlling the cleaning device is provided.
The control device is a cooling device configured to operate the cleaning device when the value of the parameter indicates a heat exchange performance lower than the reference state.
The control device has a heat exchange performance in which the value of the parameter acquired by the control device using the sensor after executing the defrosting operation for removing the frost adhering to the evaporator is lower than the reference state. The cooling device according to claim 1, which is configured to operate the cleaning device when shown.
The parameter is the difference between the temperature of the air in the cooling target space where the refrigerant exchanges heat in the evaporator and the evaporation temperature of the refrigerant in the evaporator.
The cooling device according to claim 1 or 2, wherein the control device is configured to operate the cleaning device when the difference becomes larger than a threshold value.
The sensor is
The first sensor that measures the temperature of the air and
The cooling device according to claim 3, further comprising a second sensor for measuring the temperature or pressure of the refrigerant passing through the evaporator.
The evaporator is further equipped with a fan for supplying air in the space to be cooled.
The parameter is the flow rate of air passing through the ventilation gap formed on the surface of the evaporator.
The cooling device according to claim 1 or 2, wherein the control device is configured to operate the cleaning device when the flow rate becomes smaller than a threshold value.
The cooling device according to claim 1, wherein the control device is configured to repeatedly operate the cleaning device until the heat exchange performance increases from the reference state.
In the control device, the number of times the cleaning device is repeatedly operated while the heat exchange performance is once lower than the reference state and then the heat exchange performance is lower than the reference state is equal to or greater than the determination value. The cooling device according to claim 6, wherein the cooling device is configured to warn the user in the case of a case.