CN115667820A

CN115667820A - Cold/heat source unit, refrigeration cycle device, and refrigerator

Info

Publication number: CN115667820A
Application number: CN202080101071.4A
Authority: CN
Inventors: 筑山亮; 石川智隆; 野本宗
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2020-05-26
Filing date: 2020-05-26
Publication date: 2023-01-31
Also published as: EP4160119A4; EP4160119A1; WO2021240645A1; JP7341337B2; JPWO2021240645A1

Abstract

A cold-heat source unit (2) is provided with: a 1 st flow path (F1) configured to receive the refrigerant from the evaporator (60) and send the refrigerant to the 1 st expansion device (50) via the compressor (10) and the condenser (20); a 2 nd flow path (F2) for sending the refrigerant having passed through the condenser (20) to the compressor (10) without passing through the 1 st expansion device (50) and the evaporator (60); a 2 nd expansion device (92) provided in the 2 nd flow path (F2); and a plurality of temperature sensors (121-123) disposed in the 2 nd flow path (F2). The control device (100) is configured to control the refrigeration cycle device (1) so that the temperatures detected by the plurality of temperature sensors are equal, calculate an average value of the temperatures detected by the plurality of temperature sensors, and perform correction of each of the plurality of temperature sensors based on the difference between the temperature detected by each of the plurality of temperature sensors and the average value.

Description

Cold/heat source unit, refrigeration cycle device, and refrigerator

Technical Field

The present disclosure relates to a cold-heat source unit, a refrigeration cycle device, and a refrigerator.

Background

Japanese patent No. 5505477 discloses an air conditioning apparatus capable of performing appropriate operation and determining whether the amount of refrigerant is appropriate with a small determination error at low cost even if there is an influence of external disturbance such as dirt of an outdoor heat exchanger, an installation condition of an outdoor unit, and wind and rain.

Documents of the prior art

Patent document

Patent document 1: japanese patent No. 5505477

Disclosure of Invention

Problems to be solved by the invention

Japanese patent No. 5505477 determines whether the amount of refrigerant is appropriate based on the degree of supercooling of the refrigerant in the air conditioner. In the detection of the degree of supercooling, it is necessary to detect the temperature by a temperature sensor or the like, but the temperature sensor usually has a manufacturing variation in the temperature detection value. Therefore, there is room for improvement in order to determine whether or not the refrigerant amount is appropriate with high accuracy. There is also a refrigeration cycle apparatus such as a refrigerator in which a liquid receiver (receiver) is generally provided between a condenser and an expansion valve. In a refrigeration cycle device provided with a liquid receiver, the degree of subcooling at the outlet of a condenser does not change much even if the amount of refrigerant is reduced at a stage where the amount of liquid refrigerant changes slightly in the liquid receiver. Therefore, in the method described in japanese patent No. 5505477, when the amount of leakage of the refrigerant is not large, the decrease in the amount of the refrigerant cannot be detected.

In recent years, there has been a demand for the suppression of the discharge of freon, and in refrigerators, there has been a demand for a Global Warming Potential (GWP) of less than 1500 for a refrigerant to be sealed, and it is obligatory for an equipment manager to report a refrigerant leakage amount of a certain amount or more.

An object of the present disclosure is to disclose a cold-heat source unit of a refrigeration cycle apparatus, and a refrigerator, which are capable of detecting leakage of a refrigerant with high accuracy at a stage where the amount of leakage is small.

Means for solving the problems

The present disclosure relates to a cold and heat source unit connected to a load device including a 1 st expansion device and an evaporator to constitute a refrigeration cycle device. The cold/heat source unit includes: a compressor; a condenser; a 1 st flow path configured to receive the refrigerant from the evaporator and send the refrigerant to a 1 st expansion device via the compressor and the condenser; a 2 nd flow path for sending the refrigerant having passed through the condenser to the compressor without passing through the 1 st expansion device and the evaporator; a 2 nd expansion device provided in the 2 nd flow path; a plurality of temperature sensors disposed in the 2 nd flow path; and a control device configured to control the refrigeration cycle device based on outputs of the plurality of temperature sensors. The control device is configured to control the refrigeration cycle apparatus so that the temperatures detected by the plurality of temperature sensors are equal to each other, and to calculate an average value of the temperatures detected by the plurality of temperature sensors, and the control device is configured to perform correction of each of the plurality of temperature sensors based on a difference between the temperature detected by each of the plurality of temperature sensors and the average value.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the cold/heat source unit of the refrigeration cycle apparatus, and the refrigerator of the present disclosure, leakage of the refrigerant can be detected with high accuracy at a stage where the amount of leakage is small.

Drawings

Fig. 1 is a diagram showing the configuration of a refrigeration cycle apparatus 1 according to embodiment 1.

Fig. 2 is a diagram for explaining the structure of a liquid receiver according to embodiment 1.

Fig. 3 is a flowchart for explaining the process of determining the refrigerant shortage performed by the control device 100.

Fig. 4 is a diagram for explaining the correction of the temperature sensor.

Fig. 5 is a graph showing a relationship between a detection error range of the temperature sensor and a required heater capacity.

Fig. 6 is a flowchart for explaining the detection of the refrigerant composition and the control according to the composition.

Fig. 7 is a diagram for explaining detection of the composition of the refrigerant in step S26.

Fig. 8 is a diagram for explaining a relationship between the composition and the evaporation temperature.

Fig. 9 is a graph showing a relationship between the averaged sensor number and the temperature error.

Fig. 10 is a diagram showing the configuration of a refrigeration cycle apparatus 1A according to embodiment 2.

Fig. 11 is a diagram showing an example 1 of the shape of a branch at the branch point BP.

Fig. 12 is a diagram showing an example 2 of the shape of a branch at the branch point BP.

Detailed Description

Hereinafter, embodiments will be described in detail with reference to the drawings. Hereinafter, a plurality of embodiments will be described, but it is planned to appropriately combine the configurations described in the respective embodiments from the beginning of the application. In the drawings, the same or corresponding portions are denoted by the same reference numerals, and description thereof will not be repeated.

Embodiment mode 1

In recent years, from the viewpoint of preventing Global Warming, air-conditioning apparatuses sometimes use a mixed refrigerant in which a refrigerant composed of a single component is mixed with another refrigerant having a lower Global Warming Potential (GWP) to lower the GWP. In the mixed refrigerant, there are an azeotropic refrigerant and a non-azeotropic refrigerant.

When a plurality of components of a refrigerant are mixed at a certain fixed ratio, the azeotropic refrigerant exhibits a fixed boiling point, and the composition in the gas phase and the liquid phase is the same, and exhibits a phase change as if it were one component. The azeotropic refrigerant has a characteristic that the temperature is equal at the same pressure in the phase change as the two-phase state, but the non-azeotropic refrigerant has a characteristic that the temperature changes in the phase change at the same pressure.

In the case of a refrigeration cycle apparatus using a non-azeotropic refrigerant, it is preferable to change the control in accordance with the composition because the composition of the refrigerant circulating varies depending on the operating state of the refrigeration cycle apparatus. The following describes the structure of the refrigeration cycle apparatus.

Fig. 1 is a diagram showing the configuration of a refrigeration cycle apparatus 1 according to embodiment 1. The refrigeration cycle apparatus uses a non-azeotropic mixed refrigerant. In fig. 1, the connection relationship and the arrangement structure of each device in the refrigeration apparatus are functionally shown, and the arrangement in the physical space is not necessarily shown.

Referring to fig. 1, the refrigeration cycle apparatus 1 includes a cold-heat source unit 2, a load device 3, and

extension pipes

83 and 87.

The cold heat source unit 2 of the refrigeration cycle apparatus 1 is configured to be connected to the load device 3 through

extension pipes

83 and 87. The cold/heat source unit 2 is not particularly limited, but is often disposed outdoors or outdoors, and is therefore also referred to as an outdoor unit or an outdoor unit.

The cold/heat source unit 2 includes a compressor 10, a condenser 20, a liquid receiver (receiver) 30, and pipes 80 to 82, 88. The liquid receiver 30 is disposed between the

pipes

81 and 82 and configured to store the refrigerant.

The load device 3 includes the 1 st expansion device 50, the evaporator 60, and the

pipes

84, 85, and 86. The expansion device 1 is, for example, a temperature expansion valve controlled independently of the cold source unit 2.

The 1 st flow path F1 extending from the pipe 88 to the compressor 10, the pipe 80, the condenser 20, the pipe 81, the liquid receiver 30, and the pipe 82 is configured to form a circulation flow path through which the refrigerant circulates together with the load device 3. Hereinafter, this circulation flow path is also referred to as a "main circuit" of the refrigeration cycle. The 1 st flow path F1 is configured to receive the refrigerant from the evaporator 60 and send the refrigerant to the 1 st expansion device 50 via the compressor 10 and the condenser 20.

The heat source unit 2 further includes a 2 nd flow path F2. The 2 nd flow path F2 is configured to send the refrigerant having passed through the condenser 20 to the compressor 10 without passing through the 1 st expansion device 50 and the evaporator 60. The 2 nd flow path F2 includes a pipe 91, a pipe 93, and a 2 nd expansion device 92 disposed between the pipe 91 and the pipe 93. As the 2 nd expansion device 92, for example, a capillary tube can be used. The pipe 91 is configured to allow the refrigerant to flow from the liquid receiver 30 in the 1 st flow path F1 to the 2 nd expansion device 92. The pipe 93 is configured to allow the refrigerant that has passed through the 2 nd expansion device 92 to flow to the pipe 88 connected to the inlet of the compressor 10. Hereinafter, the 2 nd flow path F2 branched from the main circuit and delivering the refrigerant to the compressor 10 via the 2 nd expansion device 92 will also be referred to as an "injection flow path".

The liquid receiver 30 is disposed downstream of the condenser 20 in the 1 st flow path F1, and is connected to the 1 st end of the 2 nd flow path F2.

The cold/heat source unit 2 further includes a heater 40 and temperature sensors 121 to 123. The heater 40 is provided downstream of the 2 nd expansion device 92 in the 2 nd flow path F2, and heats the refrigerant flowing through the pipe 93. As the temperature sensors 121 to 123, for example, thermistors can be used.

A suction port G1 of the compressor 10 is connected to the pipe 88, and a discharge port G2 is connected to the pipe 80. The compressor 10 has a suction port G1 and a discharge port G2. The compressor 10 is configured to draw in the refrigerant that has passed through the evaporator 60 from the suction port G1 and discharge the refrigerant from the discharge port G2 toward the condenser 20.

The compressor 10 is configured to adjust the rotation speed in accordance with a control signal from the control device 100. The refrigeration capacity of the refrigeration cycle apparatus 1 can be adjusted by adjusting the rotation speed of the compressor 10 to adjust the circulation amount of the refrigerant. As the compressor 10, various types of compressors can be employed, and for example, a scroll type, a rotary type, a screw type, or the like can be employed.

The condenser 20 condenses the refrigerant discharged from the compressor 10 to the pipe 80, and then flows to the pipe 81. The condenser 20 is configured to exchange heat between the high-temperature and high-pressure gas refrigerant discharged from the compressor 10 and outside air. By this heat exchange, the refrigerant after heat dissipation condenses and changes to a liquid phase or a two-phase. The fan, not shown, supplies the condenser 20 with outside air that is heat-exchanged by the refrigerant in the condenser 20. The refrigerant pressure on the discharge side of the compressor 10 can be adjusted by adjusting the rotation speed of the fan.

The liquid receiver 30 stores the liquid refrigerant flowing from the condenser 20. The gas refrigerant mixed in the liquid refrigerant is separated from the liquid refrigerant in the liquid receiver 30, and the liquid refrigerant is discharged from the pipe 82.

The cold-heat source unit 2 further includes

pressure sensors

110 and 111 and a controller 100 for controlling the cold-heat source unit 2.

The pressure sensor 110 detects a pressure PL of the refrigerant sucked into the compressor 10, and outputs a detection value thereof to the control device 100. The pressure sensor 111 detects a pressure PH of the refrigerant discharged from the compressor 10, and outputs a detected value thereof to the control device 100.

The temperature sensor 121 detects the temperature T1 of the refrigerant in the pipe 91 connecting the liquid receiver 30 and the 2 nd expansion device 92, and outputs the detected value to the control device 100. The temperature sensor 122 detects a temperature T2 of the refrigerant flowing through a portion of the pipe 93 upstream of the heater 40, and outputs the detected value to the control device 100. The temperature sensor 123 detects a temperature T3 of the refrigerant flowing through a portion of the pipe 93 downstream of the heater 40, and outputs the detected value to the control device 100.

The control device 100 includes a CPU (Central Processing Unit) 102, a Memory 104 (Read Only Memory (ROM) and Random Access Memory (RAM)), an input/output buffer (not shown) for inputting/outputting various signals, and the like. The CPU102 loads and executes a program stored in the ROM into the RAM and the like. The program stored in the ROM is a program in which processing procedures of the control device 100 are described. The control device 100 executes control of each device in the cold/heat source unit 2 according to these programs. This control is not limited to software-based processing, and may be performed by dedicated hardware (electronic circuit).

In the present embodiment, the control device 100 is configured to perform a) determination of the amount of refrigerant sealed in the refrigeration cycle apparatus 1, and b) control of the cold source unit 2 corresponding to the refrigerant composition circulating in the main circuit of the refrigeration cycle apparatus 1.

Referring to fig. 2, the liquid receiver 30 includes a casing 31 for storing a liquid refrigerant, an inlet pipe IP1, a 1 st outlet pipe OP1, and a 2 nd outlet pipe OP2.

An outlet from the liquid receiver 30 to the 1 st flow path F1 which is a part of the main circuit is a 1 st outlet pipe OP1. The 2 nd outlet pipe OP2 is an outlet from the liquid receiver 30, which is different from the 1 st outlet pipe OP1.

The pipe 91 is configured to allow the refrigerant to flow from the 2 nd outlet pipe OP2 to the inlet of the 2 nd expansion device 92. In the liquid receiver 30, the suction port of the 2 nd outlet pipe OP2 is disposed at a position higher than the suction port of the 1 st outlet pipe OP1. Whether or not the amount of refrigerant sealed in the refrigeration cycle apparatus 1 is appropriate can be determined based on the state of the refrigerant sucked from the pipe 91.

Specifically, the height L1 of the suction port of the 1 st outlet pipe OP1 and the height L2 of the suction port of the 2 nd outlet pipe OP2 are lower than the liquid surface height L0 when the refrigerant amount is appropriate. However, the height L2 of the suction port of the 2 nd outlet pipe OP2 is between the height L1 and the height L0, and the position in the height direction is determined in accordance with the sensitivity of the refrigerant shortage to be detected. When the height L2 is set close to the height L0, the gas refrigerant is sucked only by a slight decrease in the liquid surface of the refrigerant, and therefore, the detection sensitivity for the shortage of refrigerant becomes high. Conversely, if the height L2 is set close to the height L1, the gas refrigerant cannot be sucked if the liquid level of the refrigerant is only slightly lowered, and therefore, although the refrigerant shortage can be detected, the detection sensitivity is lowered.

Fig. 3 is a flowchart for explaining the process of determining the refrigerant shortage performed by the control device 100. The processing of this flowchart is periodically executed during the operation of the refrigeration cycle apparatus 1. For example, the execution frequency can be about 1 time per day. Referring to fig. 3, in step S11, control device 100 sets heater 40 to an OFF state. Thereby, the refrigerant temperatures upstream and downstream of the heater 40 become the same temperature. Therefore, if the

temperature sensors

122, 123 have no error, the temperature T2 and the temperature T3 should be equal.

In step S12, the control device 100 detects the refrigerant temperature T2 on the inlet side and the refrigerant temperature T3 on the outlet side of the heater 40, and corrects the

temperature sensors

122 and 123. As an example of the correction, a difference between the average value and the measurement value may be used as a correction amount. Specifically, the difference Δ T2 between the average value Tave and the detection temperature T2c at the time of correction is subtracted from the detection temperature T2, and the difference Δ T3 between the average value Tave and the detection temperature T3c at the time of correction is subtracted from the detection temperature T3.

The following expressions (1) to (3) show examples of specific correction expressions.

Tave = (T2 c + T3 c)/2 (heater off state) … (1)

Δ T2= T2c-Tave (heater off state) … (2)

Δ T3= T3c-Tave (heater off state) … (3)

The symbols of the formulae (1) to (3) represent the following.

T2c: heater inlet detection temperature during calibration

T3c: heater outlet detection temperature during calibration

Tave: average temperature of heater inlet temperature and heater outlet temperature at the time of correction

Δ T2: correction value of heater inlet temperature detection unit

Δ T3: correction value of heater outlet temperature detection unit

Next, in step S13, the control device 100 turns ON the heater 40, and corrects the temperatures detected by the

temperature sensors

122 and 123 according to the following equations (4) to (5).

T2' = T2- Δ T2 (heater on state) … (4)

T3' = T3- Δ T3 (heater on state) … (5)

Each symbol of equations (4) to (5) represents the following.

T2: heater inlet detection temperature before correction

T3: heater outlet detection temperature before correction

T2': corrected heater inlet detection temperature

T3': corrected heater outlet detection temperature

Thereafter, the values T2 'and T3' corrected by the correction values Δ T2 and Δ T3 are used for the measurement values of the

temperature sensors

122 and 123 until the next correction.

Fig. 4 is a diagram for explaining the correction of the temperature sensor.

In general, when N individuals are randomly taken from the normal population N (μ, σ ^ 2) and averaged, it becomes a new normal population N (μ, σ ^ 2/N). This means that if the heater is turned off and the average value of the detection value of the temperature sensor 122 and the detection value of the temperature sensor 123 is taken, the detection error becomes 1/√ 2.

If n is further increased to 2, the error can be further reduced. For example, the temperature sensor 121 at the upstream portion of the 2 nd expansion device 92 can be used for a stable state in which the compressor 10 is stopped. In this case, n =3, and the average value Tave, the correction values Δ T1 to Δ T3, and the corrected temperatures T1 'to T3' are expressions (6) to (12) below.

Tave = (T1 c + T2c + T3 c)/3 (heater and compressor off state) … (6)

Δ T1= T1c-Tave (heater off state) … (7)

Δ T2= T2c-Tave (heater off state) … (8)

Δ T3= T3c-Tave (heater off state) … (9)

T1' = T1- Δ T1 (heater on state) … (10)

T2' = T2- Δ T2 (heater on state) … (11)

T3' = T3- Δ T3 (heater on state) … (12)

In the case where another temperature sensor is used in the refrigeration cycle, the temperature sensors may be corrected by increasing the number of n under an operating condition in which n (n is a natural number of 4 or more) temperature sensors including the temperature sensor detect the same temperature.

Returning again to fig. 3, after the heater is turned on in step S13, the amount of refrigerant is determined in steps S14 and S15.

As a premise for executing the refrigerant amount determination process, as shown in fig. 2, the position of the 2 nd outlet pipe OP2 for introducing the liquid refrigerant into the injection flow path needs to be appropriate. By setting the height L2 appropriately, the liquid refrigerant is sent from the liquid receiver 30 to the injection flow path when the refrigerant quantity is appropriate, and the gas refrigerant is sent when the liquid refrigerant is insufficient.

When the amount of refrigerant is appropriate, the liquid refrigerant is decompressed by the 2 nd expansion device 92, and as a result, a two-phase refrigerant flows into the pipe 93. The refrigerant is heated by the heater 40.

Next, in step S14, the control device 100 detects the temperature T2 of the refrigerant on the upstream side and the temperature T3 of the refrigerant on the downstream side of the heater 40 using the

temperature sensors

122 and 123. Then, control device 100 determines whether or not the difference between temperature T2 and temperature T3 of the refrigerant is greater than a threshold value.

If the amount of refrigerant is appropriate and the two-phase refrigerant flows through the pipe 93, the temperature difference is equal to or less than the threshold value (no in S14). On the other hand, if the amount of refrigerant is insufficient compared to the appropriate amount, the refrigerant flowing through the pipe 93 is in a gaseous state midway through the refrigerant, and therefore all the heat given by heating becomes sensible heat, and the temperature difference becomes larger than the threshold value (yes in S14). When the temperature difference is larger than the threshold value, control device 100 determines that the refrigerant is insufficient in step S15, and contacts the user.

The heater 40 is used to determine the shortage of refrigerant as shown in fig. 3, but there is an effect that the capacity of the heater 40 can be made small by reducing the error of the temperature sensor.

The following heater capacities are required in the heater 40: when the refrigerant is heated by the heater 40, the temperature sensor can detect whether there is a temperature increase. Therefore, when the detection error of the temperature sensor is large, the amount of heat generated per hour needs to be increased in order for the temperature sensor to detect a reliable increase in the refrigerant temperature. The amount of heat generated per hour is proportional to the heater capacity (W). Conversely, in the case where the detection error of the temperature sensor is small, the heater capacity may be small.

Fig. 5 is a graph showing a relationship between a detection error range of the temperature sensor and a required heater capacity. For example, in the case where the error of the temperature sensor is 1.5 ℃, the required heater capacity is 9W. On the other hand, fig. 5 shows that in the same apparatus, the heater capacity can be reduced to about 6.6W by the present embodiment when the error of the temperature sensor is reduced to 1.1 ℃.

In other words, when error correction is not performed, the maximum error is 1.5 ℃, and when 2 sensors are averaged and corrected for use, the maximum error can be expected to be 1.1 ℃. When the refrigerant temperature is increased by 1.5 ℃ or more, a heater of 9W is required, but when the refrigerant temperature is used by correction, the temperature can be detected by the temperature sensor if the refrigerant temperature is increased by 1.1 ℃ or more, and therefore, the heater that can be used in this case can be reduced to 6.6W.

In addition, in the present embodiment, detection of the refrigerant composition is performed in addition to detection of the shortage of refrigerant.

Referring to fig. 6, when the refrigerant shortage determination of fig. 5 is performed in advance, control device 100 determines whether or not the amount of refrigerant is appropriate in step S21, and stops the operation of the refrigeration cycle apparatus when the amount of refrigerant is not appropriate (no in S21). On the other hand, if the amount of refrigerant is appropriate (no in S21), control device 100 executes the process of detecting the refrigerant composition after step S22. In addition, the processing of step S21 is not necessarily performed simultaneously with the composition detection.

In step S22, the heater 40 is not used in the composition detection, and therefore the control device 100 sets the heater 40 to the off state. Then, in step S24, the control device detects the temperatures T1 to T3 and the pressure PL. The temperatures T1 to T3 are corrected values.

In the case of the non-azeotropic refrigerant, the composition of the refrigerant circulating in the refrigeration cycle apparatus is determined by the ratio of the mass of the gas refrigerant in the liquid receiver 30 to the mass of the entire enclosed refrigerant. For example, when the liquid receiver 30 is full of liquid and no gas refrigerant is present, the composition of the circulating refrigerant matches the composition at the time of sealing. However, when the gas refrigerant is present in the liquid receiver 30, the gas refrigerant remains in the liquid receiver 30 and does not circulate through the refrigeration cycle apparatus. Therefore, the composition of the refrigerant circulating in the refrigeration cycle apparatus is the composition of the refrigerant other than the gas refrigerant in the liquid receiver 30.

First, in step S24, control device 100 converts temperature T1 into enthalpy H1. In the liquid phase region of the p-h diagram, the isotherm shows that the enthalpy does not change even if the pressure of the refrigerant changes. Therefore, if the temperature of the liquid refrigerant is measured, the enthalpy corresponds to 1. Therefore, the conversion table is stored in the memory in advance, and the temperature T1 can be directly converted into the enthalpy H1 by referring to the conversion table. The enthalpy H1 does not change when adiabatically expanded by the 2 nd expansion device 92. Therefore, the enthalpy of the refrigerant flowing through the pipe 93 downstream of the 2 nd expansion device 92 is also the enthalpy H1.

Next, in step S25, control device 100 calculates an average value Tave of the detection values of

temperature sensors

122 and 123 before and after heater 40. When the heater 40 is in the off state, the average value Tave is used as the detection value, and thus it is expected that the temperature detection error is reduced.

In step S26, control device 100 detects the composition of the refrigerant from enthalpy H1, pressure PL, and temperature Tave.

Generally, a non-azeotropic refrigerant can be determined as to its composition by finding its saturation temperature from pressure and enthalpy if the composition can be determined, and conversely, it can be determined as to its composition if the pressure, enthalpy and saturation temperature are known.

More specifically, on the premise that the composition is known, if 2 of the pressure, enthalpy, and temperature are known, the other 1 is known as the refrigerant. Furthermore, if 3 of pressure, enthalpy, temperature are known, the composition is known.

Applying this principle, the control device 100 determines the refrigerant composition using a function or a conversion map prepared in advance, using the pressure PL and the temperature Tave measured by the pressure sensor 110 and the enthalpy H1 calculated from the temperature T1 measured by the temperature sensor 121.

Fig. 7 is a diagram for explaining detection of the composition of the refrigerant in step S26. In fig. 7, the relationship between the composition and the temperature in a state where the pressure and the enthalpy are fixed is shown. Here, a relationship between the composition and the temperature of a portion where the refrigerant composition is detected, that is, a low-pressure portion (pressure PL) in an injection flow path in the refrigeration cycle device is shown. In fig. 7, the vertical axis shows the average temperature Tave of 2 temperature sensors of the refrigerant at the outlet of the 2 nd expansion device 92, and the horizontal axis shows the weight ratio of the amount of gaseous refrigerant/the amount of enclosed refrigerant in the accumulator 30 in percentage. In fig. 7, the enthalpy H1 and the pressure PL converted from the temperature T1 are fixed to certain values. Under this condition, the temperature Tave corresponds to the weight ratio of the amount of gas refrigerant/the amount of enclosed refrigerant in a 1 to 1 manner. For example, the temperature Tave when the liquid receiver 30 is in a liquid-full state and the composition of the circulating refrigerant is a pure composition of the non-azeotropic refrigerant is-39.8 ℃ and the actual temperature Tave is-38 ℃. Therefore, the deviation Δ T with respect to the temperature at the time of pure composition corresponds to 25% in the weight ratio (%) of the amount of gas refrigerant/the amount of enclosed refrigerant shown on the horizontal axis.

Since the weight ratio of the amount of gas refrigerant/the amount of enclosed refrigerant corresponds to the composition of the circulating refrigerant, if the temperature Tave is known, the composition of the circulating refrigerant can be determined. The relationship shown in such a graph exists for each pressure and each enthalpy. Therefore, a map for determining the composition of the refrigerant can be created from the pressure PL, the temperature Tave, and the enthalpy H1 (or the temperature T1).

The above-described process for determining the composition of the circulating refrigerant is executed in step S26. Next, in step S27, the control device 100 makes the conversion expression of the pressure and the evaporation temperature correspond to the detected composition. Here, the evaporation temperature is the dew-boiling average evaporation temperature.

Fig. 8 is a diagram for explaining the relationship between the composition and the evaporation temperature. In fig. 8, the relationship between the composition and the temperature in a state where the pressure and the enthalpy are fixed is shown. Here, the relationship between the composition and the temperature of a portion to be reflected in the control of the refrigeration cycle apparatus, that is, a low-pressure portion in the refrigeration cycle apparatus is shown. In fig. 8, the vertical axis shows the average evaporating temperature of the evaporator 60, and the horizontal axis shows the weight ratio of the amount of gaseous refrigerant/the amount of enclosed refrigerant in the accumulator 30 in percentage.

The graph shown in fig. 8 corresponds to a map for reflecting the detected composition to the control. For example, assuming that the liquid receiver 30 is in a full liquid state and the average evaporation temperature when the composition of the circulating refrigerant is a pure composition of the non-azeotropic refrigerant is-40 ℃, when 25% is applied to the weight ratio (%) of the amount of the gas refrigerant/the amount of the enclosed refrigerant corresponding to the composition in the map shown in fig. 8, the average evaporation temperature becomes-38.5 ℃.

Next, in step S27, control device 100 determines pressure PL for controlling the refrigeration cycle device as suction pressure so that the average evaporation temperature obtained in step S36 is achieved, and control device 100 changes the operating frequency of compressor 10 so that pressure PL is obtained.

That is, control device 100 controls compressor 10 with the pressure corresponding to the saturation temperature suitable for the detected composition as the target value of pressure PL on the inlet side of compressor 10.

When the process of step S27 is completed, the control returns to the main routine. In the case of the non-azeotropic refrigerant, when the amount of liquid in the liquid receiver 30 changes by repeating the process shown in the flowchart of fig. 6, the control of the compressor 10 is performed according to the composition of the circulating refrigerant. In this way, the control device 100 is configured to reflect the change in the composition of the refrigerant in the cycle of the non-azeotropic refrigerant in the control, and maintain the cooling capacity of the refrigeration cycle device.

Fig. 9 is a graph showing a relationship between the averaged sensor number and the temperature error. According to the present embodiment, even if the detection accuracy of the temperature sensor is low, the capability maintenance control suitable for the composition of the non-azeotropic refrigerant can be executed with high accuracy. For example, as shown by the circular marks in fig. 9, since the error of the temperature sensor is reduced from 1.5 ℃ to 1.1 ℃ by averaging 2 sensors and correcting, the accuracy of controlling the evaporation temperature is improved.

It is desirable that the control error of the evaporation temperature indicated by the triangular mark is made close to zero, and when the error of the sensor detection temperature as an input decreases, the error of the control target value ET of the evaporation temperature derived therefrom also becomes small as shown in fig. 9.

When the number n of averaged sensors is 2 or more, it can be expected to further reduce the error.

The refrigerant shortage determination control based on the liquid level detection shown in fig. 3 and the refrigerant composition detection control shown in fig. 6 are executed in no order. However, since the accuracy of the refrigerant composition detection process of fig. 6 may deteriorate when the refrigerant is insufficient, it is preferable to perform the control in the order of fig. 3 and 6. For example, it is also considered that the refrigerant shortage determination process is executed 1 time on 1 day, and the refrigerant composition detection process is executed with further increased frequency.

Embodiment mode 2

In embodiment 1, the end of the 2 nd flow path F2 (injection flow path) is directly connected to the upper part of the liquid receiver 30, but in embodiment 2, an example of connection to other parts will be described.

Fig. 10 is a diagram showing the structure of a refrigeration cycle apparatus 1A according to embodiment 2. Referring to fig. 10, the refrigeration cycle apparatus 1A includes a cold heat source unit 2A, a load device 3, and

extension pipes

83 and 87. The cold/heat source unit 2A is connected to the load device 3 via

extension pipes

83 and 87. The load device 3 and the

extension pipes

83 and 87 are the same as those of embodiment 1 shown in fig. 1, and therefore, the description thereof will not be repeated.

The cold source unit 2A includes the liquid receiver 30A instead of the liquid receiver 30 and the

pipes

82A and 91A instead of the

pipes

82 and 91, respectively, in the configuration of the cold source unit 2 shown in fig. 1. The other configurations of the heat source unit 2A are the same as those of the heat source unit 2, and therefore, the description thereof will not be repeated.

The liquid receiver 30A is connected to the pipe 82A instead of the pipe 82, except for the pipe 91 in addition to the structure of the liquid receiver 30 shown in fig. 1 and 2. The liquid receiver 30A is the same as the liquid receiver 30 with respect to the connection between the housing 31 and the pipe 81.

In embodiment 2, as shown in fig. 10, the pipe 91A branches off from the pipe 82A at a branch point BP. That is, in embodiment 2, the connection of the 2 nd flow path F2 (injection flow path) is performed not from the liquid receiver but from the pipe. At the branch point BP, a structure of gas-liquid separation of the refrigerant is adopted. Hereinafter, an example of a specific gas-liquid separation mechanism that easily flows only the gas refrigerant to the pipe 91A when the refrigerant is insufficient will be described.

Fig. 11 is a diagram showing an example 1 of the shape of a branch at a branch point BP. In fig. 11, the pipe 82A at the branch point BP extends in the horizontal direction, and the pipe 91A branches off from the pipe 82A vertically upward. When the refrigerant is insufficient, the two-phase refrigerant flows from the liquid receiver 30A to the pipe 82A. With the configuration shown in fig. 11, when the refrigerant is insufficient, the liquid refrigerant falls by gravity, and only the gas refrigerant rises and flows into the pipe 91A, so that gas-liquid separation can be performed at the branch point BP.

Fig. 12 is a diagram showing a 2 nd example of the shape of the branch at the branch point BP. In fig. 12, the pipe 82A is bent vertically downward from the horizontal direction at the branch point BP, and the pipe 91A is branched vertically upward from the pipe 82A. By adopting the configuration shown in fig. 12, when the refrigerant is insufficient, the liquid refrigerant flows significantly downward by the action of gravity, and only the gas refrigerant rises and flows into the pipe 91A, as compared with the configuration shown in fig. 11. Therefore, in the configuration shown in fig. 12, gas-liquid separation can be performed more reliably when the refrigerant at the branch point BP is insufficient.

(conclusion)

As shown in fig. 1 and 10, the present disclosure relates to a

cold source unit

2 or 2A, and the

cold source unit

2 or 2A is connected to a load device 3 including an evaporator 60 of the 1 st expansion device 50 to constitute a

refrigeration cycle device

1 or 1A. The cold

heat source unit

2 or 2A includes: a compressor 10; a condenser 20; a 1 st flow path F1 configured to receive the refrigerant from the evaporator 60 and send the refrigerant to the 1 st expansion device 50 via the compressor 10 and the condenser 20; a 2 nd flow path F2 for sending the refrigerant having passed through the condenser 20 to the compressor 10 without passing through the 1 st expansion device 50 and the evaporator 60; a 2 nd expansion device 92 provided in the 2 nd flow path F2; a plurality of temperature sensors (121-123) disposed in the 2 nd flow path F2; and a control device 100 configured to control the

refrigeration cycle apparatus

1 or 1A based on outputs of the plurality of temperature sensors. The control device 100 is configured to control the

refrigeration cycle apparatus

1 or 1A so that the temperatures detected by the plurality of temperature sensors are equal to each other, and to calculate an average value of the temperatures detected by the plurality of temperature sensors. The control device 100 is configured to perform correction of each of the plurality of temperature sensors based on a difference between the temperature detected by each of the plurality of temperature sensors and the average value.

In this way, since the deviation from the correct value due to the deviation of the detection values of the plurality of temperature sensors is reduced as a whole, it is possible to expect an improvement in the accuracy of control of the refrigeration cycle apparatus.

Preferably, the cold heat source unit 2 shown in fig. 1 further includes: a liquid receiver 30 which is disposed downstream of the condenser 20 in the 1 st flow path F1, is connected to the 1 st end of the 2 nd flow path F2, and stores the liquid-phase refrigerant; and a heater 40 provided downstream of the 2 nd expansion device 92 in the 2 nd flow path F2. As shown in fig. 1 and 2, the 1 st end of the 2 nd flow path F2 is disposed so as to draw the liquid-phase refrigerant from the liquid receiver 30 when the amount of the refrigerant sealed in the refrigeration cycle apparatus 1 is not insufficient. The 2 nd end of the 2 nd flow path F2 is connected to the suction port G1 of the compressor 10. The plurality of temperature sensors includes a 1 st temperature sensor 122 and a 2 nd temperature sensor 123. The 1 st temperature sensor 122 and the 2 nd temperature sensor 123 are disposed upstream and downstream of the heater 40 of the 2 nd flow path F2, respectively. The control device 100 performs the correction of the 1 st temperature sensor 122 and the 2 nd temperature sensor 123 while the heater 40 is turned off. The control device 100 determines whether or not the amount of refrigerant sealed in the refrigeration cycle device 1 is insufficient based on the difference (T3-T2) between the temperatures detected by the 1 st temperature sensor 122 and the 2 nd temperature sensor 123 with the heater 40 turned on.

In this way, the capacity of the heater 40 can be reduced, and the refrigerant shortage can be detected with high accuracy.

More preferably, the cold/heat source unit 2 further includes a pressure sensor 110, and the pressure sensor 110 detects the pressure of the refrigerant sucked by the compressor 10. The plurality of temperature sensors further includes a 3 rd temperature sensor 121, and the 3 rd temperature sensor 121 is disposed upstream of the 2 nd expansion device 92 in the 2 nd flow path F2. The 1 st temperature sensor 122 is disposed between the 2 nd expansion device 92 and the heater 40 in the 2 nd flow path F2. The refrigerant is a non-azeotropic refrigerant mixture. The control device 100 determines the composition of the refrigerant based on the outputs of the pressure sensor 110 and the 1 st to 3

rd temperature sensors

122, 123, and 121, and controls the refrigeration cycle device 1 with the pressure corresponding to the saturation temperature corresponding to the composition as a target value and with the pressure as a target value of the detection pressure of the pressure sensor 110.

As described above, in the present embodiment, focusing on the detection error of the temperature sensor such as the thermistor, the accuracy of refrigerant composition detection and the accuracy of refrigerant shortage determination can be improved by reducing the detection error.

Further, the correction may be performed using 2 average values of the

temperature sensors

121 and 122. Preferably, the cold

heat source unit

2 or 2A further includes a pressure sensor 110, and the pressure sensor 110 detects the pressure of the refrigerant sucked by the compressor 10. The plurality of temperature sensors includes a 1 st temperature sensor (121) and a 2 nd temperature sensor (122). The 1 st temperature sensor (121) and the 2 nd temperature sensor (122) are disposed upstream and downstream of the 2 nd expansion device 92 of the 2 nd flow path F2, respectively. The control device 100 performs correction of the 1 st temperature sensor (121) and the 2 nd temperature sensor (122) in a state where the compressor 10 is stopped. The refrigerant is a non-azeotropic refrigerant mixture. The control device 100 determines the composition of the refrigerant based on the outputs of the pressure sensor 110, the 1 st temperature sensor (121), and the 2 nd temperature sensor (122), and controls the refrigeration cycle device 1 with the pressure corresponding to the saturation temperature corresponding to the composition as a target value and with the pressure as a target value of the detection pressure of the pressure sensor 110.

For example, even when the refrigerant shortage determination using the heater is not performed, the present embodiment focuses on the detection error of the temperature sensor such as the thermistor, and the accuracy of the refrigerant composition detection can be improved by reducing the detection error.

Preferably, as shown in fig. 10 and 11, the 2 nd flow path F2 branches off vertically upward from the portion of the 1 st flow path F1 extending in the horizontal direction downstream of the condenser 20 in the 1 st flow path F1.

Preferably, as shown in fig. 10 and 12, the 2 nd flow path F2 branches from the 1 st flow path F1 at a branch point BP downstream of the condenser 20 of the 1 st flow path F1. At the branch point BP, the 1 st flow path F1 extends from the horizontal direction toward the vertically downward direction. At the branch point BP, the 2 nd flow path F2 extends vertically upward.

The present disclosure relates to a

refrigeration cycle apparatus

1, 1A in another aspect, and the

refrigeration cycle apparatus

1, 1A includes any of the cold/

heat source units

2 or 2A described above and a load device 3. Further, the present invention relates to a refrigerator including the

refrigeration cycle apparatus

1, 1A.

The embodiments disclosed herein are illustrative in all respects and should not be considered restrictive. The essential scope of the present disclosure is shown by the claims, and not the description of the above embodiments, and is intended to include all modifications within the meaning and scope equivalent to the claims.

Description of the reference numerals

1. A 1A refrigeration cycle apparatus, a 2, 2A cold-heat source unit, a 3-load device, a 10 compressor, a 20 condenser, a 30, 30A liquid receiver, a 31 casing, a 40 heater, a 50 st expansion device, a 60 evaporator, 80, 81, 82A, 84, 85, 86, 88, 91A, 93 piping, 83, 87 extension piping, a 92 nd expansion device, a 100 control device, 102cpu,104 memory, 110, 111 pressure sensors, 121 to 123 temperature sensors, BP branching points, F1, F2 flow paths, G1 suction port, G2 discharge port, IP1 inlet piping, OP1 st 1 outlet piping, OP2 nd 2 outlet piping.

Claims

1. A cold-heat source unit connected to a load device including a 1 st expansion device and an evaporator to constitute a refrigeration cycle device, wherein,

the cold/heat source unit includes:

a compressor;

a condenser;

a 1 st flow path configured to receive the refrigerant from the evaporator and send the refrigerant to the 1 st expansion device via the compressor and the condenser;

a 2 nd flow path for sending the refrigerant having passed through the condenser to the compressor without passing through the 1 st expansion device and the evaporator;

a 2 nd expansion device provided in the 2 nd flow path;

a plurality of temperature sensors disposed in the 2 nd flow path; and

a control device configured to control the refrigeration cycle device based on outputs of the plurality of temperature sensors,

the control device is configured to control the refrigeration cycle device so that the temperatures detected by the plurality of temperature sensors are equal to each other, and to calculate an average value of the temperatures detected by the plurality of temperature sensors,

the control device is configured to perform correction of each of the plurality of temperature sensors based on a difference between the temperature detected by each of the plurality of temperature sensors and the average value.

2. The cold heat source unit according to claim 1,

the cold/heat source unit further includes:

a liquid receiver which is disposed downstream of the condenser in the 1 st flow path, is connected to the 1 st end of the 2 nd flow path, and stores the refrigerant in a liquid phase; and

a heater provided downstream of the 2 nd flow path from the 2 nd expansion device,

the 1 st end of the 2 nd flow path is configured to draw the refrigerant in a liquid phase from the liquid receiver without an insufficient amount of the refrigerant sealed in the refrigeration cycle apparatus,

a 2 nd end of the 2 nd flow path is connected to a refrigerant inlet of the compressor,

the plurality of temperature sensors includes a 1 st temperature sensor and a 2 nd temperature sensor,

the 1 st temperature sensor and the 2 nd temperature sensor are disposed upstream and downstream of the heater of the 2 nd flow path, respectively,

the control device executes the correction of the 1 st temperature sensor and the 2 nd temperature sensor in a state that the heater is turned off,

the control device determines whether or not the amount of the refrigerant sealed in the refrigeration cycle device is insufficient based on a difference between the detected temperatures of the 1 st temperature sensor and the 2 nd temperature sensor in a state where the heater is turned on.

3. The cold heat source unit according to claim 2,

the cold-heat source unit further includes a pressure sensor that detects a pressure of the refrigerant sucked by the compressor,

the plurality of temperature sensors further includes a 3 rd temperature sensor, the 3 rd temperature sensor being disposed upstream of the 2 nd expansion device in the 2 nd flow path,

the 1 st temperature sensor is disposed between the 2 nd expansion device and the heater of the 2 nd flow path,

the refrigerant is a non-azeotropic refrigerant mixture,

the control device determines the composition of the refrigerant based on the outputs of the pressure sensor and the 1 st temperature sensor, the 2 nd temperature sensor, and the 3 rd temperature sensor, and controls the refrigeration cycle device with a pressure corresponding to a saturation temperature corresponding to the composition as a target value and with the pressure as a target value of a detection pressure of the pressure sensor.

4. The cold heat source unit according to claim 1,

the 1 st temperature sensor and the 2 nd temperature sensor are disposed upstream and downstream of the 2 nd expansion device of the 2 nd flow path, respectively,

the control device executes the correction of the 1 st temperature sensor and the 2 nd temperature sensor in a state that the compressor is stopped,

the refrigerant is a non-azeotropic refrigerant mixture,

the control device determines the composition of the refrigerant based on the outputs of the pressure sensor, the 1 st temperature sensor, and the 2 nd temperature sensor, and controls the refrigeration cycle device with a pressure corresponding to a saturation temperature corresponding to the composition as a target value and with the pressure corresponding to a detection pressure of the pressure sensor as a target value.

5. The cold heat source unit of claim 1,

the 2 nd flow path branches off vertically upward from a portion of the 1 st flow path extending in the horizontal direction downstream of the condenser in the 1 st flow path.

6. The cold heat source unit according to claim 1,

the 2 nd flow path branches from the 1 st flow path at a branch point downstream of the condenser of the 1 st flow path,

at the branching point, the 1 st flow path extends from the horizontal direction toward the vertically downward direction,

at the branching point, the 2 nd flow path extends vertically upward.

7. A refrigeration cycle apparatus, wherein,

the refrigeration cycle device is provided with the cold heat source unit according to any one of claims 1 to 6, and the load device.

8. A refrigerator, wherein a refrigerator body is provided,

the refrigerator includes the refrigeration cycle apparatus according to claim 7.