JP4407010B2 - Refrigeration equipment - Google Patents

Description

【００３０】
【表２】

なお、液回収制御は必ずしも周期的に行う必要はなく、高圧圧力が所定値になると実行する等、冷媒回路(1)のパラメータに基づいて適宜実行するようにしてもよい。
【図面の簡単な説明】
【図１】 実施形態に係る冷凍装置の冷媒回路図である。
【図２】 液回収制御のフローチャートである。
【図３】 室外熱交換器における液冷媒の溜まり具合を模式的に示した図であり、（ａ）は電磁弁を閉鎖した状態、（ｂ）は電磁弁を開放した状態を示す。
【図４】 従来の冷凍装置の冷媒回路図である。
【符号の説明】
(1) 冷媒回路
(2a,2b) 圧縮機
(3) 室外熱交換器（熱源側熱交換器）
(4) 高圧レシーバ
(5) 室内電動弁（減圧機構）
(6) 室内熱交換器（利用側熱交換器）
(17) 低圧配管（低圧ライン）
(18) アキュムレータ
(20) ガス抜き管（配管）
(21) 電磁弁（開閉弁）
(28) 圧力センサ（圧力検出手段）
(31) コントローラ（開閉制御手段）[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a refrigeration apparatus, and more particularly to a technique for improving the capacity of a refrigeration apparatus.
[0002]
[Prior art]
Conventionally, as shown in FIG. 4, for example, as a compressor (101), an outdoor heat exchanger (102) as a heat source side heat exchanger, a high pressure receiver (103), an expansion valve (104), and a use side heat exchanger A refrigeration apparatus including a refrigerant circuit having the indoor heat exchanger (105) is well known. In such a refrigeration system, the high-pressure receiver (103) absorbs fluctuations in the refrigerant circulation amount due to changes in the operating state, stably distributes the refrigerant to each indoor heat exchanger (105) during cooling operation, etc. Playing a role. In addition, a gas vent pipe (107) is provided in the high pressure receiver (103) to equalize the pressure during shutdown or to prevent an excessive decrease in the low pressure side pressure during operation. Devices connected to the pressure equalizing tube (108) are also known.
[0003]
[Problems to be solved by the invention]
In such an apparatus, during the cooling operation, the outdoor heat exchanger (102) serves as a condenser for condensing the refrigerant. By the way, when the pressure loss at the outlet side portion of the outdoor heat exchanger (102) is increased by an accessory device such as a shunt capillary tube or a motor operated valve provided in the refrigerant circuit, the outdoor heat exchanger (102) has liquid refrigerant inside. It becomes easy to collect. When a large amount of liquid refrigerant accumulates inside the outdoor heat exchanger (102), the area occupied by the gas-liquid two-phase refrigerant with good heat transfer decreases in the heat exchanger. Therefore, the capacity of the outdoor heat exchanger (102) is reduced. Moreover, since the high pressure side pressure increases and the compressor input increases, the COP decreases.
[0004]
The present invention has been made in view of such a point, and an object of the present invention is to improve COP by preventing a large amount of liquid refrigerant from accumulating inside the heat source side heat exchanger. is there.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, the liquid refrigerant accumulated in the heat source side heat exchanger is collected in a high-pressure receiver.
[0006]
Specifically, the refrigeration apparatus according to the present invention includes a compressor (2a, 2b), a heat source side heat exchanger (3), a high pressure receiver (4), a pressure reducing mechanism (5), and a use side heat exchanger (6). A refrigerant circuit (1) having a refrigerant circuit (1), wherein the high-pressure receiver (4) collects liquid refrigerant accumulated in the heat source side heat exchanger (3) during cooling operation. The degassing means (20, 21) for escaping the gas refrigerant in (4) to the low pressure line (17) of the refrigerant circuit (1) is provided.
[0007]
When the liquid refrigerant accumulates inside the heat source side heat exchanger during the cooling operation due to the above items, the gas refrigerant in the high-pressure receiver is discharged to the low-pressure line by the degassing means, and the internal pressure of the high-pressure receiver decreases. As a result, a pressure difference is generated between the heat source side heat exchanger and the high pressure receiver, and this pressure difference becomes a driving force, and the liquid refrigerant accumulated in the heat source side heat exchanger is recovered by the high pressure receiver. The As a result, the accumulation of liquid refrigerant in the heat source side heat exchanger is prevented, the heat exchange performance is improved by increasing the two-phase region, and an excessive increase in the high pressure side pressure is suppressed. Therefore, the COP of the apparatus is improved.
[0008]
The degassing means includes a pipe (20) connecting the high-pressure receiver (4) and the low-pressure line (17) of the refrigerant circuit (1), and an on-off valve (21) provided in the pipe (20). , that have a switching control means (31) for opening and closing said closing valve (21).
[0009]
When the liquid refrigerant accumulates inside the heat source side heat exchanger due to the above, the on / off valve is opened by the opening / closing control means, and the gas refrigerant in the high pressure receiver is discharged to the low pressure line through the pipe. As a result, the internal pressure of the high pressure receiver temporarily decreases, and the liquid refrigerant in the heat source side heat exchanger is recovered by the high pressure receiver. When the recovery of liquid refrigerant from the heat source-side heat exchanger is completed, the closing valve is Ru is closed.
[0010]
The refrigeration apparatus includes pressure detection means (28) for detecting the high-pressure side pressure of the refrigerant circuit (1), and the open / close control means (31) detects the open / close valve (21) in a closed state. 1 is compared with the second high-pressure side pressure detected after the opening / closing valve (21) is opened for a predetermined time and then closed, and the first high-pressure side pressure and the second high-pressure side pressure are compared. based on the pressure difference as more opening and closing time interval is longer small pressure differential that is configured to regulate the opening and closing time interval of the on-off valve (21).
[0011]
When the on-off valve is opened, the liquid refrigerant in the heat source side heat exchanger is recovered by the high pressure receiver, and the high pressure side pressure in the refrigerant circuit decreases. The pressure difference between the first high-pressure side pressure and the second high-pressure side pressure depends on the amount of liquid refrigerant that has accumulated in the outdoor heat exchanger. Specifically, when the amount of liquid refrigerant accumulated in the heat source side heat exchanger is large, the difference in performance between the heat exchanger before and after recovery increases, and thus the pressure difference increases. On the other hand, when the amount of liquid refrigerant accumulated in the heat source side heat exchanger is small, only a small amount of liquid refrigerant can be recovered, so the difference in capacity of the heat exchanger before and after recovery is small. Therefore, the pressure difference is reduced. Therefore, the larger the pressure difference, the shorter the opening / closing interval, and the smaller the difference, the longer the opening / closing interval. Thereby, recovery of the liquid refrigerant from the heat source side heat exchanger is efficiently performed.
[0012]
【The invention's effect】
As described above, according to the present invention, during the cooling operation, the gas refrigerant in the high-pressure receiver is released to the low-pressure line of the refrigerant circuit, so that the liquid refrigerant collected in the heat source side heat exchanger is recovered in the high-pressure receiver. As a result, the area of the liquid refrigerant in the heat source side heat exchanger can be reduced, and the area of the two-phase refrigerant can be increased accordingly. Therefore, the capability of the heat source side heat exchanger can be improved. Moreover, the excessive raise of the high voltage | pressure side pressure of a refrigerant circuit can be suppressed. Therefore, the COP of the apparatus can be improved.
[0013]
Provided with a pipe connecting the high-pressure receiver and the low-pressure line of the refrigerant circuit, an on-off valve provided on the pipe, and an on-off control means for opening and closing the on-off valve, it is possible to change the internal pressure, Ru can be easily performed to recover the liquid refrigerant to the high pressure receiver from the heat source-side heat exchanger.
[0014]
A comparison is made between the first high-pressure side pressure detected with the on-off valve closed and the second high-pressure side pressure detected after the on-off valve has been opened for a predetermined time and then closed. If the opening / closing interval of the opening / closing valve is adjusted based on the pressure difference so as to be longer, the liquid refrigerant from the heat source side heat exchanger can be efficiently recovered.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
As shown in FIG. 1, the refrigeration apparatus according to the embodiment includes a compressor (2a, 2b), an outdoor heat exchanger (3) as a heat source side heat exchanger, a high-pressure receiver (4), an indoor motorized valve (5, 5) and a refrigerant circuit (1) provided with indoor heat exchangers (6, 6) as use side heat exchangers.
[0016]
An oil separator (7, 7) is provided on the discharge side piping of each compressor (2a, 2b). The pipes on the downstream side of the two oil separators (7, 7) merge, and the discharge pipe (9) after the merge is connected to the first port of the four-way selector valve (8). The second port of the four-way selector valve (8) is connected to the outdoor heat exchanger (3) via the pipe (10). The outdoor heat exchanger (3) and the high-pressure receiver (4) are connected by a pipe (12) provided with an outdoor motor operated valve (11). The other liquid pipe (13) of the high-pressure receiver (4) branches into a plurality of branch pipes (14, 14), and each branch pipe (14) is connected to one end of the indoor heat exchanger (6). ing. Each branch pipe (14) is provided with an indoor motorized valve (5). A branch pipe (15) is connected to the other end of each indoor heat exchanger (6). The branch pipes (15, 15) merge to form a pipe (16), which is connected to the third port of the four-way switching valve (8). A low pressure pipe (17) is connected to the fourth port of the four-way selector valve (8), and the low pressure pipe (17) is connected to the accumulator (18). The accumulator (18) is connected to the suction side of the compressor (2a, 2b) via the suction pipe (19).
[0017]
One end of a gas vent pipe (20) is connected to the upper part of the high-pressure receiver (4). The other end of the gas vent pipe (20) is connected to the low pressure pipe (17). The gas vent pipe (20) is provided with an electromagnetic valve (21) as an on-off valve.
[0018]
In addition, the refrigerant circuit (1) is provided with a cooling injection circuit (22), an oil return pipe (23, 23), and an oil equalizing pipe (24). The cooling injection circuit (22) has one end connected to the pipe (12) and the other end branched to be connected to the injection port of each compressor (2a, 2b). Each branch pipe is provided with a solenoid valve (25). The oil return pipes (23, 23) connect the oil separators (7, 7) and the suction pipe (19). The oil equalizing pipe (24) connects the oil chambers of both compressors (2a, 2b). The outdoor heat exchanger (3) is provided with an outdoor fan (26), and the indoor heat exchangers (6, 6) are provided with indoor fans (27, 27).
[0019]
The discharge pipe (9) and the suction pipe (19) are provided with pressure sensors (28, 29), respectively. Further, high pressure switches (30, 30) are provided on the discharge side of the compressors (2a, 2b). Furthermore, this refrigeration apparatus includes a controller (31) as an opening / closing control means for executing opening / closing control of the electromagnetic valve (21).
[0020]
During the cooling operation, the refrigerant circulates as follows. That is, the refrigerant discharged from the compressors (2a, 2b) is condensed in the outdoor heat exchanger (3) and then temporarily stored in the high-pressure receiver (4). The liquid refrigerant in the high-pressure receiver (4) is decompressed and expanded by each indoor motor-operated valve (5, 5), and then evaporates in each indoor heat exchanger (6). The evaporated refrigerant passes through the accumulator (18) and is then sucked into the compressors (2a, 2b).
[0021]
While such a refrigerant circulation is performed, a large amount of liquid refrigerant may accumulate in the outdoor heat exchanger (3) depending on the operation state. Therefore, in the present refrigeration apparatus, the controller (31) executes liquid recovery control for recovering the liquid refrigerant accumulated in the outdoor heat exchanger (3) to the high-pressure receiver (4). Next, the liquid recovery control will be described with reference to FIG.
[0022]
First, after starting operation, predetermined start control is performed until the operation state is stabilized, and then in step ST1, it is determined whether or not the operation mode is a cooling operation. If YES, the process proceeds to step ST2, the determining whether or not a predetermined time t ₀ after the completion of the activation control has elapsed. If YES, the process proceeds to step ST3, and the pressure sensor (28) detects the high-pressure side pressure of the refrigerant circuit (1). The pressure detected at this time is the high-pressure side pressure when the electromagnetic valve (21) is closed, and is referred to as the first pressure P1 here.
[0023]
Then, in step ST4, to solenoid valve (21) a predetermined time t ₁ open. As a result, the gas refrigerant in the high pressure receiver (4) is sucked into the low pressure pipe (17), and the internal pressure of the high pressure receiver (4) is temporarily reduced. The pressure difference between the outdoor heat exchanger (3) and the high-pressure receiver (4) becomes a driving force, and the liquid refrigerant accumulated in the outdoor heat exchanger (3) is collected by the high-pressure receiver (4). . Then, it progresses to step ST5 and the high pressure side pressure of the refrigerant circuit (1) in the state which closed the solenoid valve (21) is detected. Here, this high-pressure side pressure is referred to as a second pressure P2.
[0024]
Thereafter, in step ST6 and subsequent steps, a pressure difference ΔP (= P1−P2) between the first pressure P1 and the second pressure P2 is calculated, and the operation timing of the solenoid valve (21) is determined based on the value of the pressure difference ΔP. Adjust. Here, if the amount of liquid refrigerant that has accumulated in the outdoor heat exchanger (3) is large, the pressure difference ΔP increases, and conversely, the amount of liquid refrigerant that has accumulated in the outdoor heat exchanger (3) is small. If it is less, the pressure difference ΔP becomes smaller. Therefore, in the present embodiment, the closing timing is adjusted so that the opening / closing interval of the solenoid valve (21) becomes shorter as the pressure difference ΔP is larger.
[0025]
Specifically, in step ST6, the pressure difference ΔP is determined whether or not the first determination value _{P L} or more predetermined, if YES, the process proceeds to step ST7, the flow returns to step ST1 after the first predetermined time _{t L} has elapsed . If NO the process proceeds to step ST8, the pressure difference ΔP is determined whether the second determination value P _S or more predetermined. Here, the second determination value P _S is smaller than the first determination value P _L. If the determination result is YES in step ST8, the process proceeds to step ST9, after the second predetermined time _{t M} lapse shorter than the first predetermined time _{t L,} the flow returns to step ST1. On the other hand, the determination if the result is NO (when the pressure difference ΔP is less than the second determination value _{P S),} the process proceeds to step ST10, after the third predetermined time _{t S} has elapsed is shorter than the second predetermined time _{t M,} Return to step ST1.
[0026]
As a result of such control, as schematically shown in FIG. 3 (a), the liquid refrigerant accumulated in the outdoor heat exchanger (3) is removed from the electromagnetic valve (21) as shown in FIG. 3 (b). The amount of liquid refrigerant collected in the high-pressure receiver (4) and remaining in the outdoor heat exchanger (3) is reduced by the opening of.
[0027]
Although the liquid recovery control after the start-up control has been described here, such liquid recovery control is executed every predetermined time. As a result, the solenoid valve (21) of the gas vent pipe (20) is intermittently opened and closed, and the liquid refrigerant is periodically extracted from the outdoor heat exchanger (3). Therefore, a large amount of liquid refrigerant is prevented from accumulating in the outdoor heat exchanger (3). Therefore, the area occupied by the two-phase refrigerant in the outdoor heat exchanger (3) becomes relatively large, and the capacity of the outdoor heat exchanger (3) is improved. Further, the excessive increase in the high-pressure side pressure is suppressed, and the input of the compressors (2a, 2b) does not increase suddenly. As a result, COP is improved.
[0028]
As shown in Table 1 and Table 2, when the performance evaluation calculation was performed under predetermined conditions, the heat exchange capacity improved by about 5.5% when the liquid area ratio decreased from 8.72% to 0%. I found out that By improving this heat exchange capability, the COP is improved by about 3%.
[0029]
[Table 1]

[0030]
[Table 2]

The liquid recovery control is not necessarily performed periodically, and may be appropriately executed based on the parameters of the refrigerant circuit (1), such as being executed when the high pressure reaches a predetermined value.
[Brief description of the drawings]
FIG. 1 is a refrigerant circuit diagram of a refrigeration apparatus according to an embodiment.
FIG. 2 is a flowchart of liquid recovery control.
3A and 3B are diagrams schematically showing how liquid refrigerant accumulates in an outdoor heat exchanger, where FIG. 3A shows a state in which the electromagnetic valve is closed, and FIG. 3B shows a state in which the electromagnetic valve is opened.
FIG. 4 is a refrigerant circuit diagram of a conventional refrigeration apparatus.
[Explanation of symbols]
(1) Refrigerant circuit
(2a, 2b) Compressor
(3) Outdoor heat exchanger (heat source side heat exchanger)
(4) High pressure receiver
(5) Indoor motorized valve (pressure reduction mechanism)
(6) Indoor heat exchanger (use side heat exchanger)
(17) Low pressure piping (low pressure line)
(18) Accumulator
(20) Gas vent pipe (pipe)
(21) Solenoid valve (open / close valve)
(28) Pressure sensor (pressure detection means)
(31) Controller (open / close control means)

Claims (1)

Refrigeration apparatus having a refrigerant circuit (1) having a compressor (2a, 2b), a heat source side heat exchanger (3), a high pressure receiver (4), a pressure reducing mechanism (5), and a use side heat exchanger (6) Because
Pressure detecting means (28) for detecting the high-pressure side pressure of the refrigerant circuit (1);
The gas refrigerant in the high-pressure receiver (4) is removed from the low-pressure line of the refrigerant circuit (1) so as to collect the liquid refrigerant accumulated in the heat source side heat exchanger (3) during the cooling operation in the high-pressure receiver (4). and a venting means (20, 21) for releasing (17),
The degassing means includes a pipe (20) connecting the high-pressure receiver (4) and the low-pressure line (17) of the refrigerant circuit (1), and an on-off valve (21) provided in the pipe (20). And an opening / closing control means (31) for opening and closing the opening / closing valve (21),
The opening / closing control means (31) detects a first high pressure side pressure detected with the opening / closing valve (21) closed, and a second pressure detected after the opening / closing valve (21) has been opened for a predetermined time and then closed. The opening / closing valve (21) is opened and closed based on the pressure difference so that the opening / closing interval becomes longer as the pressure difference between the first high pressure side pressure and the second high pressure side pressure is smaller. A refrigeration apparatus configured to adjust the spacing .

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