GB2566846A

GB2566846A - Refrigerating device

Info

Publication number: GB2566846A
Application number: GB1820289.5A
Authority: GB
Inventors: Morita Hisato; Sata Hiroshi; Saito Makoto
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2016-07-14
Filing date: 2016-07-14
Publication date: 2019-03-27
Anticipated expiration: 2036-07-14
Also published as: GB2566846B; JPWO2018011935A1; GB201820289D0; WO2018011935A1; JP6636155B2

Abstract

A refrigerating device is provided with: a heat source-side unit comprising a compressor, a condenser, and a liquid receiver; a load-side unit comprising an expansion valve and an evaporator; a refrigerant circuit in which the heat source-side unit and the load-side unit are connected by piping and that circulates a refrigerant through the compressor, the condenser, the expansion valve, and the evaporator, in order; a control device that determines that the condenser is clogged; a first temperature detection unit that detects the condensation temperature; and a second temperature detection unit that detects the outdoor air temperature. The control device calculates the temperature difference of the condensation temperature and the outdoor air temperature detected by the first temperature detection unit and the second temperature detection unit, corrects the temperature difference, and determines whether the condenser is clogged using the corrected temperature difference and a threshold value A.

Description

The present invention relates to a refrigeration apparatus, and in particular, relates to a determination as to whether a condenser is clogging.

Background Art [0002]

In a typical air-cooled finned-tube condenser included in a refrigeration apparatus, the spaces between fins tend to undergo accumulation of dirt, dust, and similar substances. Thus, the condenser may be clogging with long-term use. Clogging leads to a reduction in heat transfer performance of the condenser. A reduction in heat transfer performance of the condenser results in a reduction in performance of the refrigeration apparatus. This results in an abnormal stop caused by turning off due to abnormally high pressure in some cases.

[0003]

For example, manuals typically often prompt users to visually check the degree of accumulation of dirt on a condenser and clean fins of the condenser periodically.

It is left to users to determine whether the condenser is clogging. For example, if the condenser is clogging and an end user is not aware that the fins of the condenser are covered with dirt, the clogging may be revealed by an abnormal stop resulting from an increase in pressure in summer. However, if the condenser is clogging at low outdoor air temperatures in winter, pressure may not rise to the extent that the abnormal stop is caused. Under such conditions, the refrigeration appratus may continue to operate while consuming more power than necessary.

[0004]

Clogging in a condenser results in poor cooling of the condenser, causing a condensing temperature to rise relative to an outdoor air temperature. A recently developed refrigeration apparatus determines whether a condenser is clogging by using such a phenomenon (see Patent Literature 1, for example).

[0005]

The refrigeration apparatus disclosed in Patent Literature 1 includes a temperature sensor that detects a condensing temperature and a temperature sensor that detects an outdoor air temperature. If the difference between the condensing temperature and the outdoor air temperature is greater than or equal to a threshold value for clogging determination, the apparatus determines that the condenser is clogging. When determining that the condenser is clogging, the apparatus interrupts power supply to a refrigerant circuit or activates an alarm. Such a configuration enables a determination as to whether the condenser is clogging, regardless of summer or winter.

Citation List

Patent Literature [0006]

Patent Literature 1: Japanese Unexamined Utility Model Registration Application Publication No. 4-20972 Summary of Invention

Technical Problem [0007]

In a typical refrigeration apparatus like that disclosed in Patent Literature 1, a threshold value for clogging determination is uniquely determined on the assumption that the condensing temperature rises in proportional to the outdoor air temperature. However, in a refrigeration apparatus including inverters, an operating frequency and a fan output markedly vary depending on the environment and conditions, so that the condensing temperature also markedly varies. This leads to an unstable difference between the condensing temperature and the outdoor air temperature.

Disadvantageously, such an unstable difference causes an erroneous determination that clogging has occurred despite the fact that the condenser remains substantially unclogged or the opposite erroneous determination that clogging has not occurred despite the fact that the condenser is clogging.

[0008]

Temperature detection units, such as thermistors or temperature sensors, are used to detect a condensing temperature and an outdoor air temperature. These temperature detection units may have detection errors. Detection errors cause a significant change in ratio at which clogging can be detected.

[0009]

Fig. 7 is a graph showing an example of the effects of detection errors of temperature detection units on the ratio of detectable clogging.

For example, assuming that a maximum variation in condensing temperature data obtained by a temperature detection unit is 1.50 K and a maximum variation in outdoor air temperature data obtained by a temperature detection unit is 1.20 K, a maximum variation in difference between the condensing temperature and the outdoor air temperature with 3σ is ±1.90 K. As represented in Fig. 7, if the difference between the condensing temperature and the outdoor air temperature reaches +2.40 K relative to the difference therebetween at 0% as the ratio of clogging of the condenser, or the clogging ratio reaches 48%, a value at which clogging can be detected ranges from +0.50 K to +4.30 K in consideration of variations of the temperature detection units, or the clogging ratio ranges from 13% to 71%.

[0010]

Disadvantageously, detection errors of the temperature detection units cause the difference between the condensing temperature and the outdoor air temperature to be greater than a threshold value for clogging determination despite the fact that clogging has not occurred, resulting in an erroneous determination that clogging has occurred. Furthermore, detection errors of the temperature detection units cause the difference between the condensing temperature and the outdoor air temperature to be less than the threshold value for clogging determination despite the fact that clogging has occurred, resulting in an erroneous determination that clogging has not occurred.

[0011]

The present invention has been made to overcome the above-described disadvantages, and aims to provide a refrigeration apparatus that enables a correct determination as to whether a condenser is clogging.

Solution to Problem [0012]

A refrigeration apparatus according to an embodiment of the present invention includes a heat source side unit including a compressor, a condenser, and a receiver; a load side unit including an expansion valve and an evaporator; a refrigerant circuit in which the heat source side unit and the load side unit are connected by pipes and refrigerant is sequentially circulated through the compressor, the condenser, the expansion valve, and the evaporator; a controller configured to determine whether the condenser is clogging; a first temperature detection unit configured to detect a condensing temperature; and a second temperature detection unit configured to detect an outdoor air temperature, wherein the controller is configured to calculate, based on the condensing temperature detected by the first temperature detection unit and the outdoor air temperature detected by the second temperature detection unit, a temperature difference between the condensing temperature and the outdoor air temperature, correct the temperature difference, and determine, based on the corrected temperature difference and a threshold value A, whether the condenser is clogging.

Advantageous Effects of Invention [0013]

In the refrigeration apparatus according to the embodiment of the present invention, the temperature difference between the condensing temperature detected by the first temperature detection unit and the outdoor air temperature detected by the second temperature detection unit is calculated based on the condensing temperature and the outdoor air temperature, the temperature difference is corrected, and whether the condenser is clogging is determined based on the corrected temperature difference and the threshold value A. Consequently, a detection failure or a false detection is not caused irrespective of detection errors of the first and second temperature detection units. Advantageously, whether the condenser is clogging is correctly determined.

Brief Description of Drawings [0014] [Fig. 1] Fig. 1 is a refrigerant circuit diagram illustrating a refrigeration apparatus according to Embodiment 1 of the present invention.

[Fig. 2] Fig. 2 is a functional block diagram of a controller of the refrigeration apparatus according to Embodiment 1 of the present invention.

[Fig. 3] Fig. 3 is a graph showing a change in threshold value, used to determine whether a condenser is clogging, with a change in evaporating temperature.

[Fig. 4] Fig. 4 is a flowchart of control by the refrigeration apparatus according to Embodiment 1 of the present invention and the control includes determining whether the condenser is clogging and informing of clogging.

[Fig. 5] Fig. 5 is a functional block diagram of a controller of a refrigeration apparatus according to Embodiment 2 of the present invention.

[Fig. 6] Fig. 6 is a flowchart of control by the refrigeration apparatus according to Embodiment 2 of the present invention and the control includes determining whether the condenser is clogging and informing of clogging.

[Fig. 7] Fig. 7 is a graph showing an example of the effects of detection errors of temperature detection units on the ratio of detectable clogging.

Description of Embodiments [0015]

Embodiments of the present invention will be described below with reference to the drawings. Embodiments, which will be described below, are not intended to limit the present invention. Note that the relative sizes of components illustrated in the following figures may differ from the actual relative sizes of the components.

[0016]

Embodiment 1

Fig. 1 is a refrigerant circuit diagram illustrating a refrigeration apparatus according to Embodiment 1 of the present invention.

As illustrated in Fig. 1, the refrigeration apparatus according to Embodiment 1 includes a heat source side unit 100 and a load side unit 200.

The heat source side unit 100 includes a compressor 1, a condenser 2, and a receiver 3, and corresponds to, for example, a condensing unit. The compressor 1 is inverter-driven. The condenser 2 is provided with a fan 6 for promoting heat exchange between refrigerant and outdoor air in the condenser 2, and the fan is disposed in proximity to the condenser. The receiver 3 is disposed on an outlet side of the condenser 2 and is used to store excess refrigerant.

The load side unit 200 includes an expansion valve 4 and an evaporator 5, and corresponds to, for example, a showcase or a unit cooler.

[0017]

The heat source side unit 100 is connected with the load side unit 200 by an on-site liquid extension pipe 20 and an on-site gas extension pipe 21, thus forming a refrigerant circuit in which the refrigerant is sequentially circulated through the compressor 1, the condenser 2, the receiver 3, the expansion valve 4, and the evaporator 5.

[0018]

The heat source side unit 100 includes a pressure detection unit 7 that detects a pressure on a suction side of the compressor 1, a first temperature detection unit 8 that detects the temperature of the refrigerant on the outlet side of the condenser 2, and a second temperature detection unit 9 that detects the temperature of air to be sent from the fan 6 to the condenser 2. The first temperature detection unit 8 and the second temperature detection unit 9 are, for example, thermistors or temperature sensors. The pressure detection unit 7 is, for example, a pressure sensor. The first temperature detection unit 8 and the second temperature detection unit 9 will be collectively referred to as temperature detection units.

[0019]

The pressure detected by the pressure detection unit 7 is converted into an evaporating temperature in the evaporator 5 included in the load side unit 200, and the evaporating temperature is used for clogging determination, which will be described later. The temperature detected by the first temperature detection unit 8 is used as a condensing temperature for clogging determination, which will be described later. The temperature detected by the second temperature detection unit 9 is used as an outdoor air temperature for clogging determination, which will be described later.

[0020]

As described above, the condensing temperature is detected by the first temperature detection unit 8 disposed adjacent to the outlet of the condenser 2 in Embodiment 1. The condensing temperature may be obtained in such a manner that a pressure detection unit (not illustrated) that detects a pressure on a discharge side of the compressor 1 is disposed instead of the first temperature detection unit 8 and the pressure on the discharge side of the compressor 1 detected by the pressure detection unit is converted into a condensing temperature. In the use of the pressure on the discharge side of the compressor 1, a value or condensing temperature converted from a pressure upon, for example, energization before the start of an operation, may be compared with a value detected by the second temperature detection unit 9, and error correction may be performed on these values so that there is no difference between the values. Furthermore, temperature detection units and pressure detection units may be arranged as appropriate in accordance with the specifications of the heat source side unit 100 of the refrigeration apparatus, and the condensing temperature may be obtained by using the temperature and pressure detection units.

[0021]

The refrigeration apparatus includes an inverter board 10 for changing the operating frequency of the compressor 1, a display unit 11 that informs of, for example, clogging, and a controller 30. For example, the controller 30 controls the operating frequency of the compressor 1 and the output of the fan 6, processes detection values of the pressure detection unit 7, the first temperature detection unit 8, and the second temperature detection unit 9, corrects detection errors of the temperature detection units as will be described later, performs clogging determination, and outputs an instruction to the display unit 11 to inform of clogging. [0022]

The controller 30 includes a microcomputer. The display unit 11 includes 7segment light emitting diodes (LEDs). The inverter board 10, the controller 30, and the display unit 11 may be integrated with or separate from the heat source side unit 100. Other configurations may me applied as the present embodiment as long as the inverter board 10, the controller 30, and the display unit 11 are capable of communicating with the heat source side unit 100.

[0023]

Fig. 2 is a functional block diagram of the controller 30 of the refrigeration apparatus according to Embodiment 1 of the present invention.

As illustrated in Fig. 2, the controller 30 includes a determination unit 31 that performs various determinations, a time measurement unit 32 that measures time, a compressor control unit 33 that controls the compressor 1, a fan control unit 34 that controls the fan 6, a pressure data acquisition unit 35 that acquires data (hereinafter, referred to as pressure data) about a pressure detected by the pressure detection unit 7, a calculation unit 36 that obtains an evaporating temperature at the evaporator 5 from the pressure data acquired by the pressure data acquisition unit 35 and obtains a clogging determination threshold value A, which depends on the evaporating temperature, a temperature data acquisition unit 37 that acquires data (hereinafter, referred to as temperature data) about temperatures detected by the first temperature detection unit 8 and the second temperature detection unit 9, a correction unit 38 that corrects the temperature data acquired by the temperature data acquisition unit 37 by using correction data obtained in advance, and a display control unit 39 that controls the display unit 11. In Embodiment 1, the abovedescribed correction data is stored in the correction unit 38. The correction data may be stored in any other place, for example, a storage unit (not illustrated).

[0024]

An operation of the refrigeration apparatus according to Embodiment 1 will now be described.

As illustrated in Fig. 1, the refrigerant in the refrigerant circuit is compressed into high-temperature, high-pressure superheated gas by the compressor 1 disposed in the heat source side unit 100. Then, in the condenser 2, the refrigerant exchanges heat with a medium, such as air, having a lower temperature than the superheated gas refrigerant, so that the refrigerant is condensed into mediumtemperature, high-pressure liquid refrigerant. The liquid refrigerant is stored in the receiver 3. The liquid refrigerant leaving the receiver 3 passes through the on-site liquid extension pipe 20 and is then turned into low-temperature, low-pressure, twophase gas-liquid refrigerant by the expansion valve 4 disposed in the load side unit 200. Then, the refrigerant exchanges heat with water and ambient air in the evaporator 5, so that the refrigerant is turned into a low-pressure superheated gas state. After that, the refrigerant passes through the on-site gas extension pipe 21 and is then sucked again into the compressor 1. Such a sequence of actions are performed, thus achieving a refrigeration cycle in the refrigerant circuit.

[0025]

Correction to detection errors of the first temperature detection unit 8 and the second temperature detection unit 9 will now be described. This correction is performed prior to a determination as to whether the condenser 2 is clogging. The determination will be described later.

It is unnecessary to correct detection errors of the first temperature detection unit 8 and the second temperature detection unit 9 so that detection values of the respective temperature detection units agree with true values. Other configurations may me applied as the present embodiment as long as errors of the first temperature detection unit 8 and the second temperature detection unit 9 to respective true values are the same value.

[0026]

For this reason, correction data used for correction to data about temperatures detected by the first temperature detection unit 8 and the second temperature detection unit 9 is calculated, preferably, when temperatures detected by the first temperature detection unit 8 and the second temperature detection unit 9 are similar values, for example, upon energization before the start of the operation. Upon energization before the start of the operation, the first temperature detection unit and the second temperature detection unit are allowed to detect a temperature. If there is a difference between the temperatures detected by the first temperature detection unit 8 and the second temperature detection unit 9, the correction unit 38 calculates correction data used to automatically correct either one of temperature data items such that the difference is zero, and stores the correction data. Once the correction data is calculated, it is unnecessary to calculate it again.

[0027]

Control by the refrigeration apparatus according to Embodiment 1 will now be described. The control includes determining whether the condenser 2 is clogging and informing of clogging.

Specifically, the temperature data acquisition unit 37 of the heat source side unit 100 acquires data about a condensing temperature detected by the first temperature detection unit 8 and data about an outdoor air temperature detected by the second temperature detection unit 9. The correction unit 38 corrects the condensing temperature data and the outdoor air temperature data by using the correction data calculated in advance. When a temperature difference ΔΤ (= condensing temperature - outdoor air temperature) is greater than the threshold value A, which is set to a predetermined value, the determination unit 31 determines that the condenser 2 is clogging. When it is determined that the condenser 2 is clogging, the display control unit 39 outputs an instruction to the display unit 11 to inform that the condenser 2 is clogging.

[0028]

Fig. 3 is a graph showing a change in threshold value A, used to determine whether the condenser 2 is clogging, with a change in evaporating temperature.

The threshold value A used to determine whether the condenser 2 is clogging is a value set as a function of evaporating temperature, as illustrated in Fig. 3, under fixed conditions where the operating frequency of the compressor 1 is a maximum (hereinafter, also referred to as a maximum operating frequency) and the output of the fan 6 is a maximum (hereinafter, also referred to as a maximum fan output). Under the above-described fixed conditions, the operation of the refrigeration apparatus is relatively stable.

[0029]

Fig. 4 is a flowchart of the control by the refrigeration apparatus according to Embodiment 1 of the present invention, and the control includes determining whether the condenser 2 is clogging and informing of clogging.

The control, which includes determining whether the condenser 2 is clogging and informing of clogging, performed by the refrigeration apparatus according to Embodiment 1 of the present invention will now be described.

The time measurement unit 32 measures time A elapsing from the start of a steady-state operation of the compressor 1 (step S1). The determination unit 31 determines whether the elapsed time A is longer than a first reference time (step S2). [0030]

If the determination unit 31 determines that the elapsed time A is not longer than the first reference time (No in step S2), the process returns to step S2.

If the determination unit 31 determines that the elapsed time A is longer than the first reference time (Yes in step S2), the determination unit 31 determines, based on data about the frequency of the compressor 1 controlled by the compressor control unit 33, whether the operating frequency of the compressor 1 is the maximum (step S3).

[0031]

If the determination unit 31 determines that the operating frequency of the compressor 1 is not the maximum (No in step S3), the process returns to step S2.

If the determination unit 31 determines that the operating frequency of the compressor 1 is the maximum (Yes in step S3), the determination unit 31 determines, based on data about the output of the fan 6 controlled by the fan control unit 34, whether the output of the fan 6 is the maximum value (step S4).

[0032]

If the determination unit 31 determines that the output of the fan 6 is not the maximum (No in step S4), the process returns to step S2.

If the determination unit 31 determines that the output of the fan 6 is the maximum (Yes in step S4), the pressure data acquisition unit 35 acquires data about a pressure on the suction side of the compressor 1 detected by the pressure detection unit 7 (step S5). Then, the calculation unit 36 obtains an evaporating temperature at the evaporator 5 from the data about the pressure on the suction side of the compressor 1 acquired by the pressure data acquisition unit 35, and sets the clogging determination threshold value A on the basis of the evaporating temperature (step S6).

[0033]

After that, the temperature data acquisition unit 37 acquires data about a condensing temperature detected by the first temperature detection unit 8 and data about an outdoor air temperature detected by the second temperature detection unit

9. The correction unit 38 corrects the condensing temperature data and the outdoor air temperature data by using correction data (step S7). The calculation unit 36 calculates the temperature difference ΔΤ based on the corrected condensing temperature data and the corrected outdoor air temperature data (step S8).

[0034]

The determination unit 31 determines whether the temperature difference ΔΤ obtained in step S8 is greater than the threshold value A obtained in step S6 (step S9).

[0035]

If the determination unit 31 determines that the temperature difference ΔΤ is not greater than the threshold value A (No in step S9), the process returns to step S2.

If the determination unit 31 determines that the temperature difference ΔΤ is greater than the threshold value A (Yes in step S9), the time measurement unit 32 measures time B elapsing (step S10). Then, the determination unit 31 determines whether the elapsed time B is longer than a second reference time (step S11).

[0036]

If the determination unit 31 determines that the elapsed time B is not longer than the second reference time (No in step S11), the process returns to step S2.

If the determination unit 31 determines that the elapsed time B is longer than the second reference time (Yes in step S11), the determination unit 31 determines that the condenser 2 is clogging.

[0037]

If the determination unit 31 determines that the condenser 2 is clogging, the display control unit 39 outputs an instruction to the display unit 11 to inform that the condenser 2 is clogging (hereinafter, such information will be referred to as clogging notification) (step S12). The clogging notification can be achieved by, for example, turning on an LED lamp included in the display unit 11 or causing the 7-segment LEDs included in the display unit 11 to display an abnormality code.

[0038]

For the second reference time in step S11, this value can be appropriately changed based on the environment, where the apparatus is used, and operating conditions including the specifications of the heat source side unit 100 and the specifications of the load side unit 200 connected to the heat source side unit 100. Furthermore, concrete values of parameters for clogging determination may be determined by examination on actual equipment. The threshold value A may be estimated based on the result of examination on actual equipment and be determined as a function of evaporating temperature.

[0039]

As described above, the refrigeration apparatus according to Embodiment 1 corrects data about a condensing temperature detected by the first temperature detection unit 8 and data about an outdoor air temperature detected by the second temperature detection unit 9 by using the correction data. The apparatus obtains the temperature difference ΔΤ on the basis of the corrected condensing temperature data and the corrected outdoor air temperature data. If the temperature difference ΔΤ is greater than the threshold value A, the apparatus determines that the condenser 2 is clogging, and outputs an instruction to the display unit 11 to inform that the condenser 2 is clogging. Consequently, a detection failure or a false detection is not caused irrespective of detection errors of the first and second temperature detection units. Advantageously, whether the condenser 2 is clogging is accurately determined, and information about the occurrence of clogging is achieved.

[0040]

Since clogging determination is performed only under the conditions where the maximum operating frequency and fan output, with which the operation is relatively stable, are achieved, a more accurate determination as to whether the condenser 2 is clogging is achieved without any false detection caused by the operating conditions. [0041]

Furthermore, a determination as to whether the condenser 2 is clogging is achieved for any applications of the refrigeration apparatus, for example, chilling applications and refrigerating applications, by changing the clogging determination threshold value A on the basis of the evaporating temperature.

[0042]

In Embodiment 1, data about a condensing temperature detected by the first temperature detection unit 8 and data about an outdoor air temperature detected by the second temperature detection unit 9 are corrected by using the correction data (step S7 in Fig. 4). Any correction may be performed. For example, the first temperature detection unit 8 and the second temperature detection unit 9 may be subjected to correction in advance. Such correction eliminates errors in the first temperature detection unit 8 and the second temperature detection unit 9, and further correction is not required. In this case, step S7 is not needed.

[0043]

Embodiment 2

Embodiment 2 of the present invention will be described below. In the following description, a redundant description of the details described in Embodiment is omitted and the same components as those in Embodiment 1 or equivalents are designated by the same reference signs.

[0044]

In Embodiment 1, in the case where the temperature difference ΔΤ is greater than the threshold value A and the second reference time has elapsed, it is determined that the condenser 2 is clogging. The above-described method for clogging determination in Embodiment 1 involves calculating correction data, which is used to correct data about temperatures detected by the temperature detection units, before performing clogging determination. In contrast, a method for clogging determination in Embodiment 2 uses the difference between the temperature difference ΔΤ and a temperature difference ΔΤο (hereinafter, referred to as an initial temperature difference) during an initial operation in which the condenser 2 is not clogging.

[0045]

In the method for clogging determination in Embodiment 2, correction to the temperature difference ΔΤ is achieved with the initial temperature difference ΔΤο without using correction data, which is used to correct data about temperatures detected by the temperature detection units in Embodiment 1. Advantageously, it is unnecessary to previously calculate correction data, which is used to correct data about temperatures detected by the temperature detection units, and the effects of detection errors of the first temperature detection unit 8 and the second temperature detection unit 9 can be ignored.

[0046]

The temperature difference ΔΤ is the difference between a condensing temperature detected by the first temperature detection unit 8 and an outdoor air temperature detected by the second temperature detection unit 9. If the difference between detection errors of the respective temperature detection units is large, the difference would significantly affect the ratio of detectable clogging. In contrast, if clogging determination is performed by using the difference between the temperature difference ΔΤ just before the determination and the initial temperature difference ΔΤο (= condensing temperature during the initial operation - outdoor air temperature during the initial operation) obtained in a state in which the clogging ratio is 0%, an error in the temperature difference ΔΤ is the same as that in the initial temperature difference ΔΤο. Therefore, the effects of such an error can be ignored. Whether the condenser 2 is clogging can be determined based on an index representing an increase in the temperature difference ΔΤ relative to the initial temperature difference ΔΤο. However, it is necessary to obtain the initial temperature difference ΔΤο in advance of the clogging determination.

[0047]

Fig. 5 is a functional block diagram of a controller 30a of a refrigeration apparatus according to Embodiment 2 of the present invention.

The controller 30a in Embodiment 2 includes a storage unit 40 that stores a value of the initial temperature difference ΔΤο obtained in the state in which the clogging ratio of the condenser 2 is 0%, for example, in a trial run. Before the value of the initial temperature difference ΔΤο is stored to the storage unit 40, it is necessary to match the operating conditions with the conditions for clogging determination. Specifically, to store the initial temperature difference ΔΤο in, for example, a trial run, the apparatus is temporarily operated with a maximum operating frequency and a maximum fan output, and the temperature data acquisition unit 37 acquires condensing temperature data and outdoor air temperature data at this time. The calculation unit 36 calculates the initial temperature difference ΔΤο from the condensing temperature data and the outdoor air temperature data acquired by the temperature data acquisition unit 37. The storage unit 40 stores the initial temperature difference ΔΤο. Once the initial temperature difference ΔΤο is calculated, it is unnecessary to calculate it again.

[0048]

Fig. 6 is a flowchart of control by the refrigeration apparatus according to Embodiment 2 of the present invention, and the control includes determining whether the condenser 2 is clogging and informing of clogging.

The control, performed by the refrigeration apparatus according to Embodiment 2 of the present invention, including determining whether the condenser 2 is clogging and informing of clogging will now be described.

Steps S1 to S8 are similar to those in Embodiment 1, and a description of these steps is accordingly omitted.

The determination unit 31 determines whether the difference between the temperature difference ΔΤ obtained in step S8 and the initial temperature difference ΔΤο obtained in advance and stored in the storage unit 40 is greater than the threshold value A obtained in step S6 (step S13).

[0049]

If the determination unit 31 determines that the difference between the temperature difference ΔΤ and the initial temperature difference ΔΤο is not greater than the threshold value A (No in step S13), the process returns to step S2.

If the determination unit 31 determines that the difference between the temperature difference ΔΤ and the initial temperature difference ΔΤο is greater than the threshold value A (Yes in step S13), the time measurement unit 32 measures time B elapsing (step S10). Then, the determination unit 31 determines whether the elapsed time B is longer than the second reference time (step S11).

[0050]

[0051]

If the determination unit 31 determines that the condenser 2 is clogging, the display control unit 39 outputs an instruction to the display unit 11 to inform that the condenser 2 is clogging (step S12).

[0052]

Although the threshold value A in Embodiment 2 differs from that in Embodiment 1, the threshold value A may be estimated based on the result of examination on actual equipment in the same way as in Embodiment 1 and be determined as a function of evaporating temperature.

[0053]

As described above, the refrigeration apparatus according to Embodiment 2 uses the initial temperature difference ΔΤο obtained in advance to determine whether the condenser 2 is clogging. If the difference between the temperature difference ΔΤ and the initial temperature difference ΔΤο is greater than the threshold value A, the apparatus determines that the condenser 2 is clogging, and outputs an instruction to the display unit 11 to inform that the condenser 2 is clogging. Consequently, a detection failure or a false detection is not caused irrespective of detection errors of the temperature detection units as in Embodiment 1. Advantageously, whether the condenser 2 is clogging is accurately determined, and information about the occurrence of clogging is achieved.

[0054]

Advantageously, it is unnecessary to previously calculate correction data, which is used to correct data about temperatures detected by the temperature detection units in Embodiment 1, and the effects of detection errors of the first and second temperature detection units 8 and 9 can be ignored.

[0055]

Since clogging determination is performed only under the conditions where the maximum operating frequency and fan output, with which the operation is relatively stable, are achieved, a more accurate determination as to whether the condenser 2 is clogging is achieved without any false detection caused by the operating conditions. [0056]

[0057]

Embodiment 3

Embodiment 3 of the present invention will be described below. In the following description, a redundant description of the details described in Embodiments 1 and 2 is omitted and the same components as those in Embodiments 1 and 2 or equivalents are designated by the same reference signs.

[0058]

In Embodiment 3, the threshold value A used for clogging determination described in Embodiments 1 and 2 will be described. In the refrigeration apparatuses according to Embodiments 1 and 2, a preliminary process, or the elimination of the effects of detection errors of the first temperature detection unit 8 and the second temperature detection unit 9, is performed in advance of clogging determination. The threshold value A is set on the assumption that the preliminary process is performed. If the preliminary process is not performed, a false detection or a detection failure may be caused in the refrigeration apparatuses according to Embodiments 1 and 2. For this reason, the refrigeration apparatus according to Embodiment 3 sets a threshold value A to be used if the preliminary process is not performed.

[0059]

The threshold value A is determined by selecting either one of the following two items or values: (1) the temperature difference ΔΤ at a clogging ratio at which no abnormal operation is caused, for example, 30%; and (2) a value based on which no false detection is caused by detection errors of the temperature detection units. For the item (1), the temperature difference ΔΤ at a clogging ratio at which no abnormal operation is caused, for example, 30%, may be obtained by examination on actual equipment. The item (2) needs to be set to a value based on which no false detection of clogging is caused by detection errors of the temperature detection units in the initial state in which the condenser 2 is not clogging. This value is set to a maximum detection error + a (e.g., 0.5 K). Consequently, if a temperature detection unit having the maximum detection error is used, the margin a (e.g., 0.5 K) will prevent the condenser 2 from being determined as being clogging, except when the condenser 2 is actually clogging. This setting eliminates a false detection in the initial state.

[0060]

The maximum detection error is a value obtained from specification values of a temperature detection unit to be used. Preferably, the margin a is a value that allows at least 10% clogging. This value may be obtained by examination on actual equipment in a manner similar to the item (1).

[0061]

Considering the likelihood of a false detection, the threshold value A needs to be greater than or equal to at least the value (2). For the threshold value A to be used in the control for determining whether the condenser 2 is clogging, it is therefore only required that the greater of either the value (1) or the value (2) is selected.

[0062]

Furthermore, a determination is performed as to whether the preliminary process of eliminating detection errors of the temperature detection units has been performed in advance of the control for determining whether the condenser 2 is clogging. If the preliminary process has been performed, a false detection caused by the detection errors will not occur. Therefore, the threshold value A can be fixed to the value (1), and clogging determination based on the preliminary process can be performed.

[0063]

A process of fixing the threshold value A to the value (1) because of the execution of the above-described preliminary process may be automatically performed during the control for determining whether the condenser 2 is clogging or may be manually performed in advance of the control for determining whether the condenser 2 is clogging.

[0064]

As described above, the refrigeration apparatus according to Embodiment 3 sets the threshold value A for the case where the preliminary process has not been performed. Advantageously, if the preliminary process, which is performed in advance of clogging determination in Embodiments 1 and 2, of eliminating the effects of detection errors of the temperature detection units has not been performed, the clogging determination is achieved without causing a false detection. In addition, whether the preliminary process has been performed is determined. If the preliminary process has been performed, clogging determination similar to that in Embodiments 1 and 2 is achieved. Advantageously, clogging determination is performed based on the presence or absence of execution of the preliminary process. Reference Signs List [0065] compressor 2 condenser 3 receiver 4 expansion valve 5 evaporator 6 fan 7 pressure detection unit 8 first temperature detection unit 9 second temperature detection unit 10 inverter board 11 display unit 20 on-site liquid extension pipe 21 on-site gas extension pipe 30 controller 30a controller 31 determination unit 32 time measurement unit 33 compressor control unit 34 fan control unit 35 pressure data acquisition unit 36 calculation unit 37 temperature data acquisition unit 38 correction unit 39 display control unit 40 storage unit 100 heat source side unit 200 load side unit

Claims

CLAIMS [Claim 1]

A refrigeration apparatus comprising:

a heat source side unit including a compressor, a condenser, and a receiver; a load side unit including an expansion valve and an evaporator; a refrigerant circuit in which the heat source side unit and the load side unit are connected by pipes and refrigerant is sequentially circulated through the compressor, the condenser, the expansion valve, and the evaporator;

a controller configured to determine whether the condenser is clogging; a first temperature detection unit configured to detect a condensing temperature; and a second temperature detection unit configured to detect an outdoor air temperature, wherein the controller is configured to calculate, based on the condensing temperature detected by the first temperature detection unit and the outdoor air temperature detected by the second temperature detection unit, a temperature difference between the condensing temperature and the outdoor air temperature, correct the temperature difference, and determine, based on the corrected temperature difference and a threshold value A, whether the condenser is clogging. [Claim 2]

The refrigeration apparatus of claim 1, wherein the controller includes a temperature data acquisition unit configured to acquire data about the condensing temperature detected by the first temperature detection unit and the outdoor air temperature detected by the second temperature detection unit, a correction unit configured to correct the data about the condensing temperature and the outdoor air temperature, acquired by the temperature data acquisition unit, by using correction data obtained in advance, a calculation unit configured to calculate the temperature difference, being a difference between the condensing temperature and the outdoor air temperature corrected by the correction unit, and a determination unit configured to determine that the condenser is clogging in a case where the temperature difference is greater than the threshold value A.

[Claim 3]

The refrigeration apparatus of claim 1, wherein the controller includes a temperature data acquisition unit configured to acquire data about the condensing temperature detected by the first temperature detection unit and the outdoor air temperature detected by the second temperature detection unit, a calculation unit configured to calculate the temperature difference, being a difference between the condensing temperature and the outdoor air temperature acquired by the temperature data acquisition unit, a storage unit configured to store an initial temperature difference, being a difference between the condensing temperature detected by the first temperature detection unit and the outdoor air temperature detected by the second temperature detection unit in a state in which the condenser is not clogging, and a determination unit configured to determine that the condenser is clogging in a case where a difference between the temperature difference and the initial temperature difference is greater than the threshold value A.

[Claim 4]

The refrigeration apparatus of claim 2 or 3, further comprising:

a display unit informing of clogging of the condenser, wherein the controller includes a display control unit configured to, when the determination unit determines that the condenser is clogging, output an instruction to the display unit to inform of clogging of the condenser.

[Claim 5]

The refrigeration apparatus of any one of claims 2 to 4, further comprising: a pressure detection unit configured to detect a pressure on a suction side of the compressor, wherein the controller includes a pressure data acquisition unit configured to acquire data about the pressure on the suction side of the compressor detected by the pressure detection unit, and wherein the calculation unit is configured to obtain an evaporating temperature from the pressure on the suction side of the compressor and sets the threshold value A based on the evaporating temperature.

[Claim 6]

The refrigeration apparatus of any one of claims 1 to 5, wherein the condenser is provided with a fan, and wherein the threshold value A is set to either a value greater than a maximum value of detection errors of the first and second temperature detection units or a difference between the condensing temperature and the outdoor air temperature at a clogging ratio at which no abnormal operation is caused, whichever is greater.

[Claim 7]

The refrigeration apparatus of claim 6 as dependent on claim 5, wherein the calculation unit is configured to set the threshold value A based on the evaporating temperature and a difference between the condensing temperature and the outdoor air temperature in a state in which the clogging ratio is 30%.

[Claim 8]

The refrigeration apparatus of any one of claims 2 to 7, wherein when the compressor has a maximum operating frequency, the determination unit determines whether the condenser is clogging.

[Claim 9]

The refrigeration apparatus of any one of claims 2 to 7 as dependent on claim 6, wherein when the fan is operating at a maximum output thereof, the determination unit determines whether the condenser is clogging.

[Claim 10]

The refrigeration apparatus of any one of claims 2 to 7 as dependent on claim 6, wherein when the compressor is operating at a maximum operating frequency and the fan is operating at a maximum output thereof, the determination unit determines whether the condenser is clogging.