JP2004060956A - Heat transfer system and method of operating the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat transfer system and a method of operating the same, capable of distributing a refrigerant almost evenly to each evaporator without generating the gas deficiency in the operated evaporators. <P>SOLUTION: In the heat transfer system which includes a condenser and two or more evaporators 9, forms a natural circulation cycle by connecting the condenser to the evaporator 9 through a refrigerant liquid pipe and a refrigerant gas pipe, and encloses the refrigerant in this natural circulation cycle, control valves 11 are provided on the upstream of two or more evaporators respectively and a control means 31 controlling each control valve at the time of startup is provided. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a refrigerant natural circulation type heat transfer device and an operation method.
[0002]
[Prior art]
In general, a heat transfer device using a heat pipe system in which a refrigerant is naturally circulated by changing a gas-liquid phase in a cycle is known. This type includes, for example, one condenser and one evaporator at a lower position than the condenser, and a refrigerant liquid pipe between which a liquid-phase refrigerant flows and a gas-phase refrigerant. Connected by the rising refrigerant gas pipes to form a natural circulation cycle. A refrigerant is sealed in the natural circulation cycle. The evaporator is housed in an indoor unit, and the indoor unit cools the room. In recent years, the above configuration has been proposed in which a condenser and a plurality of evaporators are provided, and these evaporators are separately installed in a plurality of indoor units.
[0003]
[Problems to be solved by the invention]
However, when evaporators are separately installed in a plurality of indoor units, there is a problem in that the refrigerant stagnates in the evaporator whose operation has been stopped, and a so-called gas shortage occurs in the evaporator in operation. Further, when the amount of the refrigerant on the refrigerant liquid tube side is insufficient, there is a problem that the refrigerant cannot be almost equally distributed to each evaporator.
[0004]
Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art, and to eliminate the lack of gas in the evaporator during operation, and to transfer the refrigerant to each evaporator almost uniformly. An object of the present invention is to provide an apparatus and an operation method.
[0005]
[Means for Solving the Problems]
The invention according to claim 1 includes a condenser and a plurality of evaporators, which are connected by a refrigerant liquid pipe and a refrigerant gas pipe to form a natural circulation cycle, and a refrigerant is sealed in the natural circulation cycle. In the heat transfer device described above, a control valve is provided upstream of each of the plurality of evaporators, and control means for controlling each control valve at the start of operation is provided.
[0006]
According to a second aspect of the present invention, in the first aspect, the control means fully closes a control valve of the evaporator to start operation and drives the blower.
[0007]
According to a third aspect of the present invention, in the second aspect, the control means fully closes a control valve of the evaporator to start operation, drives a blower, and operates a suction air temperature, a refrigerant inlet temperature, and a refrigerant. When the comparison temperature difference using the outlet temperature reaches within a predetermined temperature, the control valve is gradually opened.
[0008]
According to a fourth aspect of the present invention, in any one of the first to third aspects, when there is an evaporator whose operation has been stopped, the evaporator starts operating any of the evaporators. During a predetermined period of time, the control valve of the evaporator during operation stop is fully closed to drive the blower during operation stop.
[0009]
According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the air conditioner is installed on a ceiling or a floor portion of a building to perform air conditioning of the building.
[0010]
The invention according to claim 6 includes a condenser and a plurality of evaporators, which are connected by a refrigerant liquid pipe and a refrigerant gas pipe to form a natural circulation cycle, and a refrigerant is sealed in the natural circulation cycle. In the method of operating the heat transfer device described above, a control valve is provided upstream of each of the plurality of evaporators, and each control valve is controlled at the start of the operation.
[0011]
According to a seventh aspect of the present invention, in the sixth aspect, the control valve of the evaporator to be started to operate is fully closed to drive the blower.
[0012]
According to an eighth aspect of the present invention, in accordance with the seventh aspect, the control valve of the evaporator to be started to operate is fully closed, the blower is driven, and the suction air temperature, the refrigerant inlet temperature, and the refrigerant outlet temperature are used. When the compared temperature difference reaches within a predetermined temperature, the control valve is gradually opened.
[0013]
According to a ninth aspect of the present invention, in the device according to any one of the sixth to eighth aspects, in the case where an evaporator that is not operating is present, after any one of the evaporators starts operating, for a predetermined time, The control valve of the evaporator during operation stop is fully closed, and the blower during operation stop is driven.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described below with reference to the drawings.
[0015]
In FIG. 1, reference numeral 1 denotes a heat transfer device. The heat transfer device 1 includes a refrigerator 3 that cools water, a refrigerant-to-water heat exchanger 5 that functions as a condenser, and a plurality of indoor units 7. The indoor unit 7 houses an evaporator 9, a refrigerant regulating valve (control valve) 11, and a blower 13 for blowing air into the room. The refrigerant-to-water heat exchanger 5 is installed at a high place such as the roof of a building, for example. The indoor unit 7 is installed on the ceiling back 10 of a ceiling plate 8 in a building room, which is lower than the refrigerant-to-water heat exchanger 5, so that the suction port of the evaporator 9 is substantially at the same height. The ceiling plate 8 has a discharge port 12 corresponding to each indoor unit 7. The refrigerator 3 is, for example, an absorption refrigerator, and the refrigerator 3 and the refrigerant-to-water heat exchanger 5 are connected in a loop by a water pipe 15.
[0016]
The indoor unit 7 is connected to the refrigerant-to-water heat exchanger 5 by a refrigerant liquid pipe 17 and a refrigerant gas pipe 19 to form a natural circulation cycle. A refrigerant is sealed inside the natural circulation cycle.
[0017]
The refrigerant liquid pipe 17 includes a refrigerant liquid main pipe 17A and a plurality of refrigerant liquid branch pipes 17B connected to the refrigerant liquid main pipe 17A. The refrigerant gas pipe 19 includes a refrigerant gas main pipe 19A and a plurality of refrigerant gas pipes 19B connected to the refrigerant gas main pipe 19A. The refrigerant liquid main pipe 17A and the refrigerant gas main pipe 19A are connected to the refrigerant / water heat exchanger 5, and each refrigerant liquid branch pipe 17B and each refrigerant gas branch pipe 19B are connected to the evaporator 9 of each indoor unit 7. Due to these connection relationships, the evaporators 9 are in parallel with each other. The refrigerant adjustment valve 11 is connected to the refrigerant liquid branch pipe 17B. Further, a booster pump 21 for forcibly circulating the refrigerant is connected to the refrigerant liquid main pipe 17A.
[0018]
Here, the refrigerant liquid pipe connection point R between the refrigerant liquid main pipe 17A and the refrigerant liquid branch pipe 17B and the refrigerant gas pipe connection point S between the refrigerant gas main pipe 19A and the refrigerant gas pipe 19B are located higher than the evaporator 18. To position. Note that at least the refrigerant gas pipe connection point S may be located higher than the evaporator 18.
[0019]
Next, the operation of the heat transfer device 1 will be described.
[0020]
When the refrigerator 3 operates, cold water of, for example, 5 ° C. is supplied to the refrigerant-to-water heat exchanger 5. Then, in the refrigerant-to-water heat exchanger 5, the refrigerant is condensed, becomes a liquid refrigerant having a large specific gravity, and flows through the refrigerant liquid main pipe 17A of the refrigerant liquid pipe 17. The liquid refrigerant that has reached each refrigerant liquid pipe connection point R of the main refrigerant liquid pipe 17A flows from a high place to a low place through each refrigerant liquid branch pipe 17B by its own weight, and flows to each indoor unit 7.
[0021]
The liquid refrigerant whose refrigerant amount has been properly adjusted by the refrigerant adjustment valve 11 of the indoor unit 7 flows into the evaporator 9, where the liquid refrigerant evaporates at, for example, an evaporation temperature of 12 ° C. In this process, the liquid refrigerant becomes a gas refrigerant having a very small specific gravity, and this gas refrigerant flows through each refrigerant gas branch pipe 19B from a low place to a high place and passes through each refrigerant gas pipe connection point S because of its light weight. The refrigerant flows into the refrigerant gas main pipe 19A and is returned to the refrigerant-to-water heat exchanger 5. That is, in this system, the refrigerant naturally circulates due to the gas-liquid phase change in the natural circulation cycle.
[0022]
The air in the room passes through a ventilation port 23 provided in the ceiling plate 8, is sucked into each indoor unit 7, is cooled by the evaporator 9, is blown into the room from the discharge port 12 by the blower 13, and cools the room. Is done.
[0023]
In such a natural circulation system, the refrigerant in the cycle is naturally circulated according to the difference in specific gravity between the liquid refrigerant and the gas refrigerant. Therefore, a circulating pump or the like is not required. However, the booster pump 21 is used as an example when the natural circulation system is constructed, when it is difficult to make a drop between the refrigerant-water heat exchanger 5 and the evaporator 9.
[0024]
In the present embodiment, the refrigerant regulating valves (control valves) 11 are provided upstream of the plurality of evaporators 9 as described above, and the controller (control means) 31 controls each refrigerant regulating valve 11 when the system starts operating. Is provided.
[0025]
FIG. 2 shows a control flow by the controller 31.
[0026]
This control flow focuses on one evaporator 9. When the operation of the system is started, first, the refrigerant adjustment valve 11 of the evaporator 9 to be started is fully closed, and the corresponding blower 13 is driven (S1). This process is a process in which the liquid refrigerant stored in the evaporator 9 is vaporized, and the gas refrigerant is expelled from the evaporator 9 to the refrigerant gas branch pipe 19B side. It is determined whether or not this processing has been continuously performed for a predetermined time (S2). If the predetermined time has elapsed, the process proceeds to S3.
[0027]
In S3, it is determined whether or not the refrigerant that has fallen into the evaporator 9 to be driven has been expelled toward the refrigerant gas branch pipe 19B.
[0028]
When the blower 13 is driven with the refrigerant adjustment valve 11 fully closed and the refrigerant is not allowed to flow, the refrigerant that has fallen into the evaporator 9 is gasified by the heat dissipating action of the blower 13 and is completely moved toward the refrigerant gas branch pipe 19B. Get kicked out. In this case, finally, the suction air temperature Ta, the refrigerant inlet temperature E1, and the refrigerant outlet temperature E3 all become equal. The intake air temperature Ta is detected by a sensor T1, the refrigerant inlet temperature E1 is detected by a sensor T3, and the refrigerant outlet temperature E3 is detected by a sensor T4.
[0029]
In S3, in the process of S1 and S2, the suction air temperature Ta, the refrigerant inlet temperature E1, and the refrigerant outlet temperature E3 are always detected, and among the detected suction air temperature Ta, the refrigerant inlet temperature E1, and the refrigerant outlet temperature E3. Is compared with any one of the minimum values Min (Ta, E1, E3), and when the temperature difference falls within a certain value α, that is, When the comparison temperature difference using the suction air temperature Ta, the refrigerant inlet temperature E1, and the refrigerant outlet temperature E3 falls within the predetermined temperature α, and the following equation (1) holds,
Max (Ta, E1, E3) −Min (Ta, E1, E3) ≦ α (1)
It is estimated that the refrigerant that has fallen into the evaporator 9 has been expelled (S3), and the refrigerant regulating valve 11 is gradually opened (S5). If the expression (1) is not satisfied, the refrigerant regulating valve 11 is kept fully closed (S4). When the refrigerant regulating valve 11 is opened (S5), the valve opening of the refrigerant regulating valve 11 is controlled so as to maintain E3−E1 ≧ 3 ° C. (S6).
[0030]
The refrigerant regulating valve 11 is opened and closed by a temperature difference between the blown air temperature Tb and a preset blow target air temperature. Specifically, it is determined whether or not a predetermined time has elapsed after the blown air temperature Tb has fallen below a preset blow target air temperature (S7). It is fully closed (S8). The blowout air temperature Tb is detected by the sensor T2.
[0031]
When the evaporator 9 is restarted after the refrigerant regulating valve 11 is fully closed (S8), each step in FIG. 2 is repeated.
[0032]
When the operation of any one of the evaporators 9 is started, if there is any evaporator 9 whose operation is stopped, the refrigerant purge control is also performed on the stopped evaporator 9. In this case, the operation is performed by driving the corresponding blower 13 for a predetermined time while the refrigerant adjustment valve 11 is fully closed.
[0033]
In this embodiment, when the operation of any one of the evaporators 9 is started, the refrigerant staying in all the evaporators 9 including the stopped evaporator 9 is expelled into the refrigerant gas main pipe 19A. That is, the so-called gas shortage state is eliminated.
[0034]
In addition, the amount of the refrigerant in the refrigerant liquid pipe is sufficient, and an effect is obtained such that the refrigerant can be diverted almost equally to each evaporator 9.
[0035]
According to the above configuration, even when a large refrigerant-to-water heat exchanger 5 is required, a plurality of indoor units 7 are provided for this one refrigerant-to-water heat exchanger 5. The indoor unit 7 can be reduced in size and can be installed even in a narrow ceiling 10. Furthermore, since the indoor unit 7 is reduced in size, it is possible to carry it in by an elevator, and it becomes easy to carry the indoor unit 7 into a room of a building.
[0036]
In addition, since each indoor unit 7 is installed such that the suction ports of the evaporators 9 in the indoor units 7 are at substantially the same height, the amount of liquid refrigerant flowing into each indoor unit 7 is substantially equal. Therefore, the heat exchange (cooling) ability is equalized in any of the indoor units 7, so that the room can be uniformly cooled.
[0037]
As described above, the present invention has been described based on one embodiment, but the present invention is not limited to this.
[0038]
In the above embodiment, the case where each indoor unit 7 is installed at substantially the same height on the ceiling 10 has been described. However, although not shown, for example, in FIG. The indoor unit installed on the side where the heat load is large, and the other indoor unit 7 is the indoor unit installed on the side where the heat load is small, and the indoor unit installed on the side where the heat load is large is small. If it is installed at a position lower than the indoor unit installed on the side and closer to the refrigerant-to-water heat exchanger 5 functioning as a condenser, a large amount of liquid refrigerant flows into the indoor unit on the side with a large heat load, and cooling is performed. Since the capacity increases, an ideal cooling state can be obtained.
[0039]
In the above-described embodiment, the indoor unit 7 is installed in the back of the ceiling 10 of the building. However, the present invention is not limited to this. For example, in a “free access floor” type building, the indoor unit 7 7, the outlet of the indoor unit 7 may be connected to an outlet formed on the floor, and the conditioned air may be blown into the conditioned room through the outlet on the floor. .
[0040]
【The invention's effect】
In the present invention, when the operation of the evaporator is started, the refrigerant remaining in the evaporator is expelled into the refrigerant gas pipe, so that the so-called lack of gas state is eliminated, and the refrigerant amount in the refrigerant liquid pipe is satisfied. Thus, it is possible to obtain an effect such that the refrigerant can be almost equally distributed to each evaporator.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing one embodiment of a heat transfer device according to the present invention.
FIG. 2 is a control flow chart showing one embodiment of a heat transfer device according to the present invention.
[Explanation of symbols]
1 Heat transfer device 5 Refrigerant to water heat exchanger (condenser)
7 indoor unit 9 evaporator 11 refrigerant adjustment valve (control valve)
17 Refrigerant liquid pipe 19 Refrigerant gas pipe 31 Controller (control means)

Claims (9)

A heat transfer device comprising a condenser and a plurality of evaporators, forming a natural circulation cycle by connecting them with a refrigerant liquid pipe and a refrigerant gas pipe, and enclosing a refrigerant in the natural circulation cycle.
A heat transfer device comprising: a control valve provided upstream of each of a plurality of evaporators; and control means for controlling each control valve at the start of operation. The heat transfer device according to claim 1, wherein the control unit fully closes a control valve of the evaporator to start operation and drives the blower. The control means fully closes the control valve of the evaporator to start operation, drives the blower, and the comparison temperature difference using the suction air temperature, the refrigerant inlet temperature, and the refrigerant outlet temperature has reached a predetermined temperature or less. 3. The heat transfer device according to claim 2, wherein the control valve is gradually opened in the case. When there is an evaporator that is not operating, the control unit completely closes the control valve of the evaporator that has been stopped for a predetermined period of time after starting operation of one of the evaporators, and then stops the operation. The heat transfer device according to any one of claims 1 to 3, wherein the blower is driven. The heat transfer device according to any one of claims 1 to 4, wherein the heat transfer device is installed on a ceiling or a floor of the building to perform air conditioning of the building. A method for operating a heat transfer device comprising a condenser and a plurality of evaporators, forming a natural circulation cycle by connecting a refrigerant liquid pipe and a refrigerant gas pipe therebetween, and enclosing a refrigerant in the natural circulation cycle. ,
An operation method comprising providing control valves upstream of a plurality of evaporators, respectively, and controlling each control valve at the start of operation. The operation method according to claim 6, wherein the control valve of the evaporator to be started to operate is fully closed, and the blower is driven. When the control valve of the evaporator to start operation is fully closed, the blower is driven, and when the comparison temperature difference using the suction air temperature, the refrigerant inlet temperature, and the refrigerant outlet temperature has reached a predetermined temperature or less, the control valve concerned 8. The operating method according to claim 7, wherein is gradually released. If there is an evaporator that has been shut down, after any one of the evaporators has started operation, the control valve of the evaporator that has been shut down is fully closed for a predetermined time to drive the blower that is shut down. The driving method according to any one of claims 6 to 8, wherein:

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