GB2528215A

GB2528215A - Refrigerating device

Info

Publication number: GB2528215A
Application number: GB1519349.3A
Authority: GB
Inventors: Takeshi Sugimoto
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2013-06-18
Filing date: 2013-06-18
Publication date: 2016-01-13
Anticipated expiration: 2033-06-18
Also published as: GB201519349D0; JPWO2014203320A1; JP5968538B2; CN105308395B; CN105308395A; GB2528215B; WO2014203320A1

Abstract

A refrigerating device (1) comprises: a refrigerant circuit in which a refrigerant circulates and in which a compressor (10), a condenser (20), a throttling device (30), and an evaporator (40) are connected; an evaporator blower (41) that generates an air flow to be blown into a refrigerator (80) by passing through the evaporator (40); and a controlling unit (60) that controls at least the compressor (10) and the evaporator blower (41). R32 refrigerant, a refrigerant mixture containing at least 65 wt% of R32 refrigerant, HFO refrigerant, propane, or a refrigerant mixture containing propane is used as the refrigerant and the controlling unit (60) can run in cooling operation mode in which both the compressor (10) and the evaporator blower (41) are operated and in blower operation mode in which the compressor (10) is stopped and the evaporator blower (41) is operated.

Description

DESCRIPTION

Title of Invention

REFRIGERATING APPARATUS

Technical Field

[0001] The present invention relates to refrigerating apparatuses.

Background Art

[0002] Patent Literature 1 discloses a cooling apparatus including a body casing that accommodates therein an evaporator and an evaporator fan, which sends air to this evaporator, and is constituted of a fan cover whose front wall has an air outlet corresponding to the fan, a fan guard that is formed by combining a plurality of wires and is attached to the fan cover to cover the front side of the air outlet, and a drain pan that is disposed below the body casing and receives condensed water from the evaporator. Refrigerant sent from a compressor disposed outside flows through the evaporator and exchanges heat with inside air in this evaporator so that the refrigerant evaporates, and then returns to the compressor side. When the fan operates, inside air is taken into the body casing through an air inlet and is cooled as the inside air passes through the evaporator. The cooled air is blown out from the air outlet to the front side.

Citation List Patent Literature [0003] Patent Literature 1: Japanese Patent No. 3861240

Summary of Invention

Technical Problem [0004] In air-conditioning apparatuses and refrigerating apparatuses in the related art, refrigerant, such as R41 OA and R404A, has been used. In recent years, there has been proposed the use of low flammable refrigerant, such as R32, having a low global warming potential (GWP) value as alternative refrigerant. In an air-conditioning apparatus or refrigerating apparatus using such low flammable refrigerant, even if the refrigerant leaks outward from inside an indoor unit (a unit cooler in a refrigerating apparatus) or a refrigerant pipe (connection pipe) connected thereto, there is no problem in terms of safety because the refrigerant gas concentration normally does not increase. Low flammable gas requires high ignition energy for ignition and does not ignite unless the gas concentration in the air becomes high. Thus, even if low flammable gas leaks into a refrigerator or a freezer, a possibility of ignition is extremely low. In other words, in a case where the leakage rate into the refrigerator or the freezer is low due to slow leakage through a pinhole of the evaporator (heat exchanger), even if the low flammable gas disperses into the refrigerator or the freezer or disperses outdoors, ignition does not occur because the gas concentration does not increase. Furthermore, when the refrigeration cycle is in operation, the air in the refrigerator or the freezer is agitated by the evaporator fan so that the airflow rate is relatively high. Thus, even if the refrigerant leaks, gas concentration that may lead to ignition is not reached since the leaked refrigerant disperses.

[0005] However, when the inside temperature becomes lower than or equal to a predetermined value in the refrigerating apparatus in the related art, the refrigeration cycle stops operating and the evaporator fan also stops, causing the airflow in the refrigerator or the freezer to become relatively stable. If the refrigerant leaks in this state, the leaked refrigerant is less likely to disperse. Thus, if fluorine-based refrigerant having a larger specific gravity than air leaks, the refrigerant concentration close to the floor tends to relatively increase. Thus, for example, in a case where no flame retardation measures are taken at all and a powerful ignition source that may instantaneously generate normally-impossible high energy exists close to the floor, there remains a slight possibility of ignition.

[0006] The present invention has been made to solve the aforementioned problem, and an object thereof is to provide a refrigerating apparatus that can reduce a possibility of ignition of refrigerant even if the refrigerant is leaked from the evaporator.

Solution to Problem [0007] A refrigerating apparatus according to the present invention includes a refrigerant circuit connecting a compressor, a condenser, an expansion device, and an evaporator, and circulating refrigerant, an evaporator fan configured to generate flow of air passing through the evaporator and blown into a target cooling space, and a control unit configured to control at least the compressor and the evaporator fan.

The refrigerating apparatus uses, as the refrigerant, R32 refrigerant, a refrigerant mixture containing 65% by weight or higher of R32 refrigerant, HFO refrigerant, propane, or a refrigerant mixture containing propane. The control unit is configured to execute a first operation mode in which the compressor and the evaporator fan are both operated and a second operation mode in which the compressor is stopped and the evaporator fan is operated.

Advantageous Effects of Invention [0008] According to the present invention, since the evaporator fan can be operated even when the compressor is stopped, the air in the target cooling space can be agitated by the evaporator fan even if the refrigerant is leaked from the evaporator.

Thus, retention of the leaked refrigerant can be prevented even if the refrigerant is leaked from the evaporator, so that a possibility of ignition of the refrigerant can be further reduced.

Brief Description of Drawings

[0009] [Fig. 1] Fig. 1 is a refrigerant circuit diagram illustrating a schematic configuration of a refrigerating apparatus 1 according to Embodiment 1 of the present invention.

[Fig. 2] Fig. 2 is a timing chart illustrating an example of operation of a compressor 10, a condenser fan 21, and an evaporator fan 41 controlled by a control unit 60 in the refrigerating apparatus 1 according to Embodiment 1 of the present invention.

[Fig. 3] Fig. 3 is a timing chart illustrating a modification of operation of the compressor 10, the condenser fan 21, and the evaporator fan 41 controlled by the control unit 60 in the refrigerating apparatus 1 according to Embodiment 1 of the present invention.

[Fig. 4] Fig. 4 is a refrigerant circuit diagram illustrating a schematic configuration of a refrigerating apparatus 2 according to Embodiment 2 of the present invention.

[Fig. 5] Fig. 5 is a timing chart illustrating an example of operation of the compressor 10, the condenser fan 21, a solenoid valve 51, and the evaporator fan 41 controlled by the control unit 60 in the refrigerating apparatus 2 according to Embodiment 2 of the present invention.

Description of Embodiments

[0010] Embodiment 1 A refrigerating apparatus according to Embodiment 1 of the present invention will be described. Fig. 1 is a refrigerant circuit diagram illustrating a schematic configuration of a refrigerating apparatus 1 according to Embodiment 1. In Embodiment 1, the refrigerating apparatus 1 includes an outdoor unit (heat source unit) and an indoor unit (unit cooler) and will be described with reference to a cooling unit that cools the interior of a refrigerator as an example. As shown in Fig. 1, the refrigerating apparatus 1 has a refrigerant circuit in which a compressor 10, a condenser 20, an expansion device 30, and an evaporator 40 are connected in series in this order by refrigerant pipes. As refrigerant that circulates through the refrigerant circuit, R32 refrigerant (single component refrigerant) or a refrigerant mixture containing 65% by weight or higher of R32 refrigerant is used. Alternatively, HFO refrigerant, propane, or a refrigerant mixture containing propane may be used as the refrigerant.

[0011] The compressor 10 is a fluid machine that suctions and compresses low-temperature low-pressure refrigerant, turns it into high-temperature high-pressure refrigerant, and discharges the high-temperature high-pressure refrigerant. The compressor 10 is controlled by a control unit 60, which will be described later. The condenser 20 is a heat exchanger that condenses the refrigerant discharged from the compressor 10 by causing the refrigerant to exchange heat with an external fluid (e.g., air). The expansion device 30 decompresses and expands the refrigerant condensed by the condenser 20 and causes the refrigerant to flow out as low-temperature low-pressure two-phase gas-liquid refrigerant. As the expansion device 30, for example, an expansion valve or a capillary is used. The evaporator 40 is a heat exchanger that evaporates the two-phase gas-liquid refrigerant flowing out of the expansion device 30 by causing the two-phase gas-liquid refrigerant to exchange heat with air At least the compressor 10 and the condenser 20 are accommodated in the outdoor unit (heat source unit) of the refrigerating apparatus 1. The evaporator 40 is accommodated in the indoor unit (unit cooler) of the refrigerating apparatus 1. The expansion device 30 is accommodated in the outdoor unit or the indoor unit.

[0012] Furthermore, the refrigerating apparatus 1 has a condenser fan 21 that sends air to the condenser 20. The condenser fan 21 is controlled by the control unit 60, which will be described later. The high-temperature high-pressure gas refrigerant flowing inside the condenser 20 is cooled and condensed by exchanging heat with the air sent by the condenser fan 21.

[0013] Furthermore, the refrigerating apparatus 1 has an evaporator fan 41 that sends air to the evaporator 40. The evaporator fan 41 is controlled by the control unit 60, which will be described later. The evaporator fan 41 generates flow of air passing through the evaporator 40 and blown into a space (i.e., an example of a target cooling space) inside a refrigerator 80. The air passing through the evaporator 40 is cooled by exchanging heat with the refrigerant flowing through the evaporator 40 to become cold air. The interior of the refrigerator 80 is cooled by this cold air. An inside temperature sensor 42 that detects the inside temperature is provided inside the refrigerator 80. The inside temperature sensor 42 outputs information about the detected inside temperature to the control unit 60, which will be described below.

[0014] The control unit 60 includes, for example, a CPU, a ROM, a RAM, and an input-output port. Based on, for example, the information about the inside temperature input from the inside temperature sensor 42, the control unit 60 controls the operation of, for example, the compressor 10, the condenser fan 21, and the evaporator fan 41. The control unit 60 is at least capable of executing a cooling operation mode in which the compressor 10 and the evaporator fan 41 are both operated and an air-sending operation mode in which the compressor 10 is stopped and the evaporator fan 41 is operated.

[0015] Fig. 2 is a timing chart illustrating an example of operation of the compressor 10, the condenser fan 21, and the evaporator fan 41 controlled by the control unit 60 in the refrigerating apparatus 1 according to Embodiment 1. Fig. 2 includes (a) showing changes in the inside temperature, (b) showing the operation (ON/OFF) of the compressor 10, (c) showing the operation (ON/OFF) of the condenser fan 21, and (d) showing the operation (ON/OFF) of the evaporator fan 41. In an initial state of this timing chart, the compressor 10, the condenser fan 21, and the evaporator fan 41 are all in an operating state (ON). In other words, the cooling operation mode for cooling the interior of the refrigerator 80 is executed in the control unit 60. As shown in Fig. 2, when the cooling operation mode is executed, the inside temperature gradually decreases because the heat of air blown into the refrigerator 80 by the evaporator fan 41 is received by the evaporator 40.

[0016] When the inside temperature decreases to a predetermined lower-limit temperature Tmin or lower (time ti in Fig. 2), the control unit 60 stops the compressor and the condenser fan 21 (thermostat off). In this case, the control unit 60 makes the evaporator fan 41 continue operating (e.g., continuous operation) without stopping it. In other words, the control unit 60 executes the air-sending operation mode in place of the cooling operation mode. When the air-sending operation mode is executed, the inside temperature gradually increases because the heat of air sent into the refrigerator 80 by the evaporator fan 41 is not received by the evaporator 40.

[0017] When the inside temperature increases to a predetermined upper-limit temperature Tmax (Tmax > 1mm) or higher (time t2), the control unit 60 causes the compressor 10 and the condenser fan 21 to operate again. The evaporator fan 41 is made to continue operating. In other words, the control unit 60 executes the cooling operation mode in place of the air-sending operation mode. Thus, the inside temperature gradually decreases.

[0015] When the inside temperature decreases to the predetermined lower-limit temperature Tmin or lower (time t3), the control unit 60 stops the compressor 10 and the condenser fan 21 again and makes the evaporator fan 41 continue operating. In other words, the control unit 60 executes the air-sending operation mode in place of the cooling operation mode. Subsequently, the control of the compressor 10, the condenser fan 21, and the evaporator fan 41 based on the inside temperature is similarly repeated.

[0019] As described above, the refrigerating apparatus 1 according to Embodiment 1 includes the refrigerant circuit connecting the compressor 10, the condenser 20, the expansion device 30, and the evaporator 40, and circulating the refrigerant, the evaporator fan 41 configured to generate flow of air passing through the evaporator and blown into the target cooling space (i.e., the space inside the refrigerator 80 in this example), and the control unit 60 configured to control at least the compressor 10 and the evaporator fan 41. The refrigerating apparatus 1 uses, as the refrigerant, R32 refrigerant, a refrigerant mixture containing 65% by weight or higher of R32 refrigerant, HFO refrigerant, propane, or a refrigerant mixture containing propane.

The control unit 60 is configured to execute the cooling operation mode in which the compressor 10 and the evaporator fan 41 are both operated and the air-sending operation mode in which the compressor 10 is stopped and the evaporator fan 41 is operated.

[0020] According to this configuration, since the evaporator fan 41 can be operated even when the compressor 10 is stopped, the air inside the refrigerator 80 can be agitated by the evaporator fan 41 even if the refrigerant is leaked from the refrigerant pipe of the evaporator 40. Thus, retention of the leaked refrigerant can be prevented, so that a possibility of ignition of the refrigerant can be further reduced, whereby obtaining a refrigerating apparatus 1 having a higher level of safety.

[0021] Moreover, the refrigerating apparatus 1 according to Embodiment 1 further includes the inside temperature sensor 42 that detects the temperature (i.e., the inside temperature in this example) in the target cooling space and that outputs information about the detected temperature to the control unit 60. The control unit 60 executes the air-sending operation mode in place of the cooling operation mode when the temperature in the target cooling space decreases to the predetermined lower-limit temperature Tmin or lower during execution of the cooling operation mode, and executes the cooling operation mode in place of the air-sending operation mode when the temperature in the target cooling space increases to the predetermined upper-limit temperature Tmax or higher during execution of the air-sending operation mode.

[0022] According to this configuration, the evaporator fan 41 can be made to continuously operate even when the compressor 10 is intermittently in a thermostat-off state. Thus, retention of the leaked refrigerant can be prevented, so that a possibility of ignition of the refrigerant can be further reduced, whereby obtaining a refrigerating apparatus 1 having a higher level of safety.

[0023] Furthermore, in a case where the target cooling space is a living room, if the evaporator fan 41 is operated when the compressor 10 is in the thermostat-off state, a person inside the living room may sometimes feel discomfort. In contrast, since the target cooling space in Embodiment 1 is the refrigerator ao, materials stored inside the refrigerator 80 are not affected even if the evaporator fan 41 is operated when the compressor 10 is in the thermostat-off state.

[0024] The refrigerating apparatus 1 may sometimes be stopped for an extended period of time. Because there is a possibility of leakage of refrigerant from the evaporator 40 during an extended stopped period of the refrigerating apparatus 1, if the refrigerating apparatus 1 (compressor 10) stops, the control unit 60 may execute the air-sending operation mode in which the evaporator fan 41 alone is operated.

Furthermore, the control unit 60 may execute the air-sending operation mode if the time elapsed since the stoppage of the compressor 10 reaches a predetermined time or longer [0025] Fig. 3 is a timing chart illustrating a modification of operation of the compressor 10, the condenser fan 21, and the evaporator fan 41 controlled by the control unit 60 in the refrigerating apparatus 1 according to Embodiment 1. A bold dotted line in Fig. 3 (d) indicates that intermittent operation of the evaporator fan 41 is being performed. As shown in Fig. 3, in this modification, intermittent operation of the evaporator fan 41 is performed during periods in which the air-sending operation mode is executed (i.e., a period from time ti to time t2 and a period from time t3 and onward in Fig. 3). In this intermittent operation, for example, three-minute operation and three-minute stoppage are alternately repeated. This modification is advantageous in that power consumption of the evaporator fan 41 can be reduced during periods in which the air-sending operation mode is executed.

[0026] Embodiment 2 A refrigerating apparatus according to Embodiment 2 of the present invention will be described. Fig. 4 is a refrigerant circuit diagram illustrating a schematic configuration of a refrigerating apparatus 2 according to Embodiment 2.

Components having the same functions and effects as those in the refrigerating apparatus 1 according to Embodiment 1 will be given the same reference signs, and

descriptions thereof will be omitted.

[0027] As shown in Fig. 4, the refrigerating apparatus 2 according to Embodiment 2 further has a liquid receiver 50 provided downstream of the condenser 20 and upstream of the expansion device 30, a solenoid valve 51 (i.e., an example of an opening and closing valve) provided downstream of the liquid receiver 50 and upstream of the expansion device 30, and a suction pressure sensor 11 provided at the suction side of the compressor 10.

[0025] The liquid receiver 50 is a tank that retains liquid refrigerant flowing out of the condenser 20. The liquid receiver 50 has, for example, capacity for retaining all refrigerant in the refrigerant circuit. The solenoid valve 51 is opened and closed by being controlled by the control unit 60 and becomes, for example, fully opened when supplied with electricity and fully closed when not supplied with electricity. The suction pressure sensor 11 detects the suction pressure of the compressor 10 and outputs information about the detected suction pressure to the control unit 60.

Based on, for example, the information about the inside temperature input from the inside temperature sensor 42 and the information about the suction pressure of the compressor 10 input from the suction pressure sensor 11, the control unit 60 controls the operation of the compressor 10, the condenser fan 21, the solenoid valve 51, and the evaporator fan 41.

[0029] Fig. 5 is a timing chart illustrating an example of operation of the compressor 10, the condenser fan 21, the solenoid valve 51, and the evaporator fan 41 controlled by the control unit 60 in the refrigerating apparatus 2 according to Embodiment 2.

Fig. 5 includes (a) showing changes in the inside temperature, (b) showing changes in the suction pressure, (c) showing the operation (ON/OFF) of the compressor 10, (d) showing the operation (ON/OFF) of the condenser fan 21, (e) showing the operation (open/closed) of the solenoid valve 51, and (f) showing the operation (ON/OFF) of the evaporator fan 41. In an initial state of this timing chart, the compressor 10, the condenser fan 21, and the evaporator fan 41 are all in an operating state (ON), and the solenoid valve 51 is in an open state. In other words, the control unit 60 executes the cooling operation mode for cooling the interior of the refrigerator 80. As shown in Fig. 5, when the cooling operation mode is executed, the inside temperature gradually decreases because the heat of air blown into the refrigerator 80 by the evaporator fan 41 is received by the evaporator 40.

[0030] When the inside temperature decreases to the predetermined lower-limit temperature Tmin or lower (time til in Fig. 5), the control unit 60 sets the solenoid valve 51 to a closed state. The compressor 10, the condenser fan 21, and the evaporator fan 41 are made to continue operating. When the solenoid valve 51 is set to the closed state, the suction pressure of the compressor 10 gradually decreases because liquid refrigerant condensed by the condenser 20 is collected in the liquid receiver 50 and the amount of refrigerant flowing through the expansion device 30 and the evaporator 40 decreases.

[0031] When the suction pressure of the compressor 10 decreases to a predetermined pressure POor lower (time t12), the control unit 60 stops the compressor 10 and the condenser fan 21 and makes the evaporator fan 41 continue operating (e.g., continuous operation). In other words, the control unit 60 executes the air-sending operation mode in place of the cooling operation mode. In this case, the pressure P0 is set to a value that causes the refrigerant to hardly remain in the evaporator 40 and to be collected in the liquid receiver 50. The operation of the evaporator fan 41 may be intermittent operation.

[0032] When the inside temperature increases to the predetermined upper-limit temperature Tmax or higher (time t13), the control unit 60 sets the solenoid valve 51 to an open state and causes the compressor 10 and the condenser fan 21 to operate again. The evaporator fan 41 is made to continue operating. In other words, the control unit 60 executes the cooling operation mode in place of the air-sending operation mode. When the solenoid valve 51 is set to the open state, the refrigerant in the liquid receiver 50 flows to the expansion device 30 and the evaporator 40 and the suction pressure of the compressor 10 increases.

[0033] Subsequently, when the inside temperature decreases to the predetermined lower-limit temperature Tmin or lower (time t14), the control unit 60 sets the solenoid valve 51 to a closed state and makes the compressor 10, the condenser fan 21, and the evaporator fan 41 continue operating, similarly to time til. When the suction pressure of the compressor 10 decreases to the pressure P0 or lower (time ti 5), the control unit 60 stops the compressor 10 and the condenser fan 21 and makes the evaporator fan 41 continue operating, similarly to time t12. Subsequently, the control of the compressor 10, the condenser fan 21, the solenoid valve 51, and the evaporator fan 41 based on the inside temperature and the suction pressure is similarly repeated.

[0034] As described above, the refrigerating apparatus 2 according to Embodiment 2 further includes the liquid receiver 50 that is provided downstream of the condenser and upstream of the expansion device 30, the solenoid valve 51 that is provided downstream of the liquid receiver 50 and upstream of the expansion device 30 and is opened and closed by being controlled by the control unit 60, and the suction pressure sensor 11 that detects the suction pressure of the compressor 10 and outputs the information about the suction pressure to the control unit 60. The control unit 60 sets the solenoid valve 51 to a closed state when the inside temperature decreases to the lower-limit temperature 1mm or lower during execution of the cooling operation mode, and executes the air-sending operation mode in place of the cooling operation mode when the suction pressure decreases to the predetermined pressure P0 or lower after the solenoid valve 51 is set to the closed state.

[0035] According to this configuration, since there is hardly any refrigerant in the evaporator 40 when the compressor 10 is stopped, the amount of leakage of refrigerant can be minimized even if the refrigerant is leaked from the refrigerant pipe of the evaporator 40. Furthermore, similarly to Embodiment 1, because the air inside the refrigerator 80 can be agitated by the evaporator fan 41, retention of the leaked refrigerant can be prevented. Thus, according to Embodiment 2, a possibility of ignition of the refrigerant can be further reduced even if the refrigerant is leaked from the refrigerant pipe of the evaporator 40, whereby obtaining a refrigerating apparatus 2 having a higher level of safety.

[0036] Other Embodiments The present invention is not limited to Embodiment 1 and Embodiment 2 described above and includes various modifications.

For example, in Embodiment 1 and Embodiment 2 described above, a cooling unit that cools the interior of the refrigerator 80 is described as an example of a refrigerating apparatus. Alternatively, the present invention can also be applied to a cooling unit that cools the interior of a freezer or to a refrigerating apparatus other than a cooling unit.

[0037] Furthermore, in Embodiment 1 and Embodiment 2 described above, the evaporator fan 41 may be performance-controllable (e.g., rotation-speed controllable).

For example, when executing the air-sending operation mode, the control unit 60 may make the evaporator fan 41 operate with relatively low performance. Moreover, when executing the air-sending operation mode, the control unit 60 may make the evaporator fan 41 operate with lower performance than the minimum performance settable during execution of the cooling operation mode.

[0038] Furthermore, Embodiment 1 and Embodiment 2 described above, and modifications may be implemented by being combined with one another.

Reference Signs List [0039] 1, 2 refrigerating apparatus 10 compressor 11 suction pressure sensor 20 condenser 21 condenser fan3o expansion device 40 evaporator 41 evaporator fan 42 inside temperature sensor 50 liquid receiver 51 solenoid valve6o control unit 80 refrigerator