JPH08312999A - Air conditioning system - Google Patents

Abstract

PURPOSE: To make a refrigerant circulation type heating system small in its size. CONSTITUTION: A conventional liquid receiving tank is dispensed with, a level switch 9 is installed on a bypass pipe 8 provided in parallel to an evaporating coil 2, and an output of the level switch 9 controls a pump 7 for returning of a liquid refrigerant. Thus a liquid receiving tank conventionally considered to be essential is omitted, an equipment can be made small-sized, and an amount of the refrigerant as required can be considerably saved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to control of refrigerant during heating of an air conditioning system.

[0002]

2. Description of the Related Art FIG. 4 shows a conventional air-conditioning system of this type. An outdoor unit 1 is installed at a high place for natural circulation by gravity during cooling operation, and this outdoor unit 1 is heated during heating. Refrigerant vapor is sent from the evaporation coil 2 to the condenser coils 4 of the plurality of indoor units 3, and a liquid storage tank 5 for receiving condensed refrigerant liquid is provided at a position lower than all the indoor units 3. The liquid receiving tank 15 is provided at a position higher than the evaporation coil 2, and the refrigerant liquid accumulated in the liquid storing tank 5 is once pumped up to the liquid receiving tank 15 by the pump 7, and then the liquid receiving tank 1
5 to the evaporation coil 2 by its own weight. The liquid receiving tank 15 is provided with a liquid level switch 9 for detecting the upper and lower liquid levels, and the pump 7 is controlled to be turned on and off by the liquid level switch 9, whereby the evaporation coil 2 is provided more than the liquid receiving tank 15. The liquid surface in the evaporation coil 2 which is provided at a lower position by a drop difference corresponding to the resistance of is maintained within a predetermined range.

[0003]

However, the above-described conventional structure requires a tank (for example, 20 liters) having a capacity about half that of the evaporating coil 2 as the liquid receiving tank 15, so that the amount of refrigerant used increases. In addition, since the height (about 1 to 3 m) corresponding to the pipe resistance is required, the total height of the outdoor unit 1 becomes high, which causes a high equipment cost and a large device. An object of the present invention is to solve such problems and to reduce the cost and the size of the apparatus by omitting the liquid receiving tank 15.

[0004]

As shown in FIG. 1, an air conditioning system according to the invention of claim 1 comprises a plurality of indoor units 3 from an evaporation coil 2 of an outdoor unit 1 installed at a high place during heating operation.
The condenser coil 4 is circulated with the refrigerant, and the liquid reservoir tank 5 for receiving the refrigerant liquid is provided at a position lower than all the indoor units 3, and the pump 7 is provided in the return refrigerant pipe 6 from the liquid reservoir tank 5 to the outdoor unit 1. In the interposed air conditioning system, the liquid level switch 9 is interposed in the bypass pipe 8 provided in parallel with the evaporation coil 2, and the pump 7 is controlled by the output of the liquid level switch 9 The liquid surface of the refrigerant is kept within a predetermined range, whereby the liquid receiving tank 1
5 is omitted, and in the invention of claim 2, instead of using the bypass pipe 8 and the liquid level switch 9 as the pump control means, as shown in FIG.
A liquid level switch 9 is provided in the refrigerant pipe 10 near the outlet of the pump 7, and the pump 7 is stopped by the upper limit output of the liquid level switch 9, and the pump 7 is stopped by the output of a timer 11 which measures a fixed time after the pump 7 is stopped. To activate the liquid level switch 9 and the evaporation coil 2 in FIG.
This eliminates the need for a drop h between the outdoor unit 1 and further miniaturizes the outdoor unit 1.

[0005]

The configuration of the present invention shown in FIG. 1 is different from the conventional configuration shown in FIG.
It is equivalent to the bypass pipe 8 provided with a liquid level switch 9 in place of the bypass pipe 8 in parallel. Thus, the liquid receiving tank 15 can be replaced by the bypass pipe 8 having a small capacity because the bypass pipe 8 is connected in parallel with the evaporation coil 2 having a large capacity.
This is because the liquid level switch 9 of FIG. 6 performs the same function as the liquid level switch 9 of the liquid receiving tank 15 by detecting the effective liquid level of the evaporating coil 2, so that even when the load suddenly changes. There is no risk of hunting due to a sudden change in the liquid level, and the liquid level of the liquid level switch 9 is stationary unlike the boiling evaporation coil 2, so that
Stable control can be performed without causing chattering.

Further, according to the second aspect of the invention shown in FIG. 2, since the liquid level switch 9 is provided near the outlet of the evaporation coil 2, the liquid level switch 9 is connected to the coil as in the case of FIG. Since it is not necessary to provide it at a high position by the drop difference h corresponding to the resistance, the outdoor unit 1 can be downsized. Further, the liquid level in the evaporation coil 2 needs to be controlled within a range from about 1/2 of its height to the upper end, and the vicinity of the liquid level is in a gas-liquid mixed state due to boiling. Is the speed at which the pump 7 is stopped immediately when the liquid level in the coil 2 rises and liquid containing bubbles is detected at the upper end position of the coil 2, and the liquid level in the coil drops when the pump is stopped. Is almost constant, the liquid level is 1
The time to fall to about 1/2 is measured in advance and set in the timer 11, and when the set time elapses, the pump 7 is restarted.
Is activated, the liquid level in the evaporation coil 2 can be maintained substantially within the above range.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of the system of the present invention, in which an outdoor unit 1 consisting of an absorption chiller is installed on the rooftop of a building and used as a heating device in winter and as a cooling device in summer. In the winter, the refrigerant (R134a or the like) vapor is circulated from the evaporation coil 2 of the outdoor unit 1 to the plurality of indoor units 3, and the condensation coil 4 of the indoor unit 3 applies heat to the indoor air to condense it. Then, while receiving the refrigerant liquid condensed in the liquid storage tank 5 provided at a position lower than all the indoor units 3,
This refrigerant liquid is pumped from the liquid reservoir 5 to the outdoor unit 1 by the pump 7 provided in the return refrigerant pipe 6. In the outdoor unit 1, a bypass pipe 8 is provided in parallel with the evaporation coil 2, and the liquid level switch 9 interposed in the bypass pipe 8 is provided.
Is controlled so that the pump 7 is stopped by the detection output of the upper limit position 9a and the pump 7 is started by the detection output of the lower limit position 9b of the liquid level switch 9, whereby the liquid level of the refrigerant in the evaporation coil 2 is changed. It is maintained within a predetermined range. In the figure, 12 and 13 are the liquid storage tank 5 and the pump 7 during the cooling operation.
Is a solenoid valve and a check valve for separating the system from the system and allowing natural circulation by gravity.

The coolant liquid sent by the pump 7 is
It is heated by the evaporation coil 2 of the outdoor unit 1 to evaporate, and is sent to each indoor unit 3 through the feed pipe 10 in a vapor state. The refrigerant vapor sent to the indoor unit 3 is condensed by the condenser coil 4 and the fan 14.
The liquid is cooled and condensed by the above, and flows down in a liquid state to be stored in the liquid storage tank 5, and then sent to the outdoor unit 1 by the pump 7. When the refrigerant liquid evaporates in the evaporation coil 2, a gas-liquid mixed state actually occurs in a certain range, and after this state, the liquid changes to vapor, but this effective liquid level is the upper end of the evaporation coil 2. If the temperature exceeds the limit, the refrigerant liquid mixes into the feed pipe 10 to impede the flow of steam, and the refrigerant liquid in the liquid storage tank 5 becomes insufficient to cause malfunction.
The heat exchange efficiency decreases as it approaches the lower end. Therefore, in order to maintain this liquid level within a certain range, the pump 7 is on / off controlled by the output of the liquid level switch 9.

In the embodiment shown in FIG. 1, a liquid level switch 9 for controlling the pump 7 is provided in a bypass pipe 8 connected in parallel with the evaporation coil 2, and the liquid level is above and below the liquid level of the evaporation coil 2. Even if the diameter of the bypass pipe 9 itself is small, it is possible to perform stable control with a small fluctuation range, like the liquid level switch 9 in the liquid receiving tank 15 having a large capacity in the conventional example, because it fluctuates according to the movement. it can. In this case, the upper end position of the bypass pipe 8 is located at the evaporation coil 2 against the pump pressure.
In consideration of the internal resistance, the upper head portion 2a of the evaporation coil 2
Since the pump pressure is zero at the lower end position of the bypass pipe 8 and the above resistance is not involved,
The space between the upper and lower end heads 2a and 2b of the evaporation coil 2 is 6
The height is 0 to 90%.

In the embodiment shown in FIG. 2, a liquid level switch 9 is provided in the refrigerant pipe 10 near the outlet of the evaporation coil 2 as a control means for the pump 7, and the pump 7 is driven by the upper limit output of the liquid level switch 9. In addition to stopping the pump 7, the pump 7 is started by the output of the timer 11 that measures a certain time after the pump 7 is stopped. This is because there is a certain range of gas-liquid mixed state above and below the effective liquid level in the evaporation coil 2, so that the liquid level switch 9 at the outlet of the evaporation coil 2 detects the upper end of the mixed state. It is possible to stop the pump 7 before the surface reaches the upper coil head, and after stopping the pump 7, the time during which the liquid level is lowered by evaporation of the refrigerant is almost constant (for example, 30 seconds to 1).
Therefore, even if the liquid level switch 9 is not provided at the lower limit position of the liquid level, by starting the pump 7 with the output of the timer 10, the control of the pump that is not much different in performance from FIG. This configuration eliminates the need for providing the bypass pipe 8 of FIG. 1 and also eliminates the need for a drop h between the upper limit contact of the liquid level switch 9 and the upper end of the evaporation coil 2 to allow outdoor use. The machine 1 can be further downsized and the cost can be reduced.

The flowchart of FIG. 3 shows still another embodiment. In the configuration of FIG. 2, the pump 7 is switched between two stages of on and off in the above embodiment, for example, high speed rotation, low speed rotation. When the liquid level switch 9 in the control device 16 detects liquid overflow, the pump 7 is switched to the next lower speed side, and when the timer 11 measures a fixed time (for example, 30 seconds), the pump is turned on. The rotation speed of 7 is returned to the high speed side, and when the liquid level switch 9 is activated again within this fixed time,
Further, the rotation speed of the pump 7 is switched to the lower speed side. According to this structure, it is possible to prevent hunting due to excessive fluctuation of the refrigerant temperature.

[0012]

According to the first aspect of the present invention, the liquid receiving tank 15 which has been indispensable in the past can be omitted and replaced with the bypass pipe 8 having a small capacity, so that the equipment can be downsized. In addition, there is an advantage that the amount of required refrigerant can be significantly reduced. Further, according to the invention of claim 2, since the upper limit position of the liquid surface can be detected near the outlet of the evaporation coil 2, the invention of claim 1 is achieved. In addition, there is no need to provide a drop h corresponding to the resistance of the coil between the liquid level switch 9 and the evaporation coil 2, and there is an advantage that the outdoor unit 1 can be further downsized.

[Brief description of drawings]

FIG. 1 is a schematic system diagram of an embodiment of the present invention.

FIG. 2 is a schematic system diagram of another embodiment of the above.

FIG. 3 is a flowchart showing still another embodiment of the above.

FIG. 4 is a schematic system diagram of a conventional example.

[Explanation of Codes] 1 Outdoor unit 2 Evaporation coil 3 Indoor unit 4 Condensing coil 5 Liquid reservoir 6 Return refrigerant pipe 7 Pump 8 Bypass pipe 9 Liquid level switch 10 Feed refrigerant pipe 11 Timer 12 Solenoid valve 13 Check valve 14 Fan 15 Liquid receiving tank 16 Control device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (71) Applicant 390003333 Shinko Industrial Co., Ltd. 1-4-5 Minamimorimachi, Kita-ku, Osaka-shi, Osaka (71) Applicant 000003621 Takenaka Corporation, Honmachi, Chuo-ku, Osaka-shi, Osaka 4-1-13-1 (72) Inventor Noboru Kobayashi 4-1-2 Hirano-cho, Chuo-ku, Osaka City Osaka Gas Co., Ltd. (72) Inventor Yutaka Takashi 4-1-2, Hirano-cho, Chuo-ku, Osaka Osaka Gas Co., Ltd. (72) Inventor Seiichiro Fujimaki 1-5-20 Kaigan, Minato-ku, Tokyo Tokyo Gas Co., Ltd. (72) Inventor Hideo Kawaguchi 19-18 Sakurada-cho, Atsuta-ku, Nagoya City Toho Gas Co., Ltd. (72) Inventor Shinji Tonmiya 4-28 Mita, Minato-ku, Tokyo Within Yazaki Corporation (72) Inventor Yasutoshi Yoshida 1-4-5 Minamimorimachi, Kita-ku, Osaka Shinko Industrial Co., Ltd. Inside the company (72) Inventor Nozomu Kusumoto 4-13 Hommachi, Chuo-ku, Osaka City Takenaka Corporation

Claims (3)

[Claims] 1. A liquid sump for circulating a refrigerant from an evaporation coil of an outdoor unit installed at a high place to a condenser coil of a plurality of indoor units during heating operation to receive the refrigerant liquid at a position lower than all indoor units. In an air conditioning system in which a tank is provided and a pump is provided in the return refrigerant pipe from the liquid reservoir to the outdoor unit, a bypass switch provided in parallel with the evaporation coil is provided with a liquid level switch, and the output of the liquid level switch The air conditioning system configured to maintain the liquid level of the refrigerant in the evaporating coil within a predetermined range by controlling the above-mentioned pump. 2. A liquid sump for circulating a refrigerant from an evaporation coil of an outdoor unit installed at a high place to a condenser coil of a plurality of indoor units during heating operation to receive the refrigerant liquid at a position lower than all the indoor units. In an air conditioning system in which a tank is provided and a pump is provided in the return refrigerant pipe from the liquid storage tank to the outdoor unit, a liquid level switch is provided in the refrigerant pipe near the outlet of the evaporation coil of the outdoor unit, The pump is stopped by the output of the liquid level switch, and the pump is started by the output of the timer that measures the fixed time after the pump is stopped, so that the liquid level of the refrigerant in the evaporation coil is maintained within a predetermined range. Air conditioning system consisting of. 3. A liquid sump for circulating a refrigerant from an evaporation coil of an outdoor unit installed at a high place to a condenser coil of a plurality of indoor units during heating operation and receiving the refrigerant liquid at a position lower than all the indoor units. In addition to providing a tank, in an air-conditioning system in which a pump is installed in the return refrigerant pipe from the liquid storage tank to the outdoor unit, a liquid level switch is installed in the refrigerant pipe near the outlet of the evaporation coil of the outdoor unit, A means for switching the number of revolutions of the pump to a plurality of stages and a timer for measuring a certain period of time after the number of revolutions is provided are provided, and the pump is switched to the one stage lower speed side by the output of the liquid level switch, and the number of revolutions of the pump becomes high after a certain period of time The air-conditioning system is configured to return to the side, and when the liquid level switch operates within the fixed time, the pump rotation speed is switched to the lower speed side.