JPH0321813B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a cooling system, and particularly to a cooling system that performs cooling or refrigeration using a gravity heat pipe.

[Prior art]

Cooling systems include air conditioning systems and refrigeration systems that cool buildings. in general,
In building air-conditioning systems, water is usually used in the form of steam, hot water or cold water as the heat transfer medium between the heat source and the air conditioning unit. by the way,
In some cases, this air conditioning unit is installed in the living room, which is the air-conditioned room, but this is not preferred because there is a risk of water leakage in the living room. Therefore, in recent building air conditioning systems, systems that use a refrigerant such as fluorocarbon instead of water as a heat medium and directly guide this refrigerant from a heat source device to a heat exchanger of an air conditioning unit are attracting attention. As one of such building air conditioning systems, the applicant has already filed an invention for an air conditioning system using gravity heat pipes (Japanese Patent Application No. 61-264309).
No.). In a building air conditioning system using gravity heat pipes, especially in the cooling circuit, there is a connection between a cold source device installed high up in the building and air conditioning units installed at various locations in the building at lower positions than the cold source device. They are connected by a gravity heat pipe. This gravity heat pipe uses a refrigerant such as fluorocarbons, and utilizes the phase change of the refrigerant during heat exchange and the fall of the liquid refrigerant due to gravity to transfer this between the air conditioning unit on the side of the conditioned room and the heat source device. Natural circulation of the refrigerant allows for heat transfer between them.
In other words, when performing cooling operation, the cold heat source is installed at a high location on the upper condensing side of the heat pipe, whereas each air conditioning unit is installed at a lower location on the lower evaporation side of the heat pipe. Because there are
The naturally circulating refrigerant condenses on the cold heat source equipment side, flows down the liquid system piping, accumulates in the heat exchanger of each air conditioning unit, undergoes heat exchange there, evaporates, and rises inside the gas system piping. This will flow back to the cold heat source device. Of course, it is also possible to replace the air conditioning unit in the cooling circuit of the above-mentioned building air conditioning system with a refrigerator or freezer and use it as a refrigeration system.

[Problems to be solved by the invention]

By the way, the flow rate control of refrigerant in each of the above-mentioned air conditioning units and cooling units such as refrigerators and freezers uses various throttling mechanisms that can increase fluid resistance, such as throttling valves, capillary tubes, orifices, and the amount of throttling is controlled by heat. This is done by adjusting it according to the load, but in gravity heat pipes, the head pressure of the liquid phase refrigerant in the liquid system piping always acts on the refrigerant in the heat exchanger of the air conditioning unit, and each cooling unit If the cooling units are arranged horizontally (individual cooling units branched from the same heat pipe are installed at the same height), the above water head pressures in each cooling unit are approximately equal, and the water head pressure is kept to a minimum. However, if the cooling units are arranged vertically (the installation heights of the individual cooling units branched from the same heat pipe are different on the first, second, and third floors, for example), In this case, the liquid system piping is full of liquid from the bottom to the height where the heat exchanger of the top cooling unit is full of liquid, and the above water head pressure in the cooling unit installed at a particularly low position is extremely high. becomes larger. Therefore, it is difficult to control the flow rate of refrigerant using a conventional throttling mechanism, and excessive throttling may result in an insufficient supply of refrigerant, resulting in a superheat state, or the flow rate of the refrigerant from the heat exchanger of the cooling unit to the cold heat source. The piping for the reflux system should be a gas system piping, but due to this large water head pressure, even the gas system piping becomes full of liquid in the low-position cooling unit, which causes the fluidity of the evaporated refrigerant to deteriorate. This causes a problem in that sufficient heat exchange is not performed in the heat exchanger and a predetermined cooling capacity cannot be achieved. Further, when a large water head pressure is applied, the evaporation temperature of the refrigerant may become high, making it impossible to achieve a predetermined cooling capacity. In this way, in a cooling system that uses gravity heat pipes, it is almost impossible to install each cooling unit that receives liquid phase refrigerant through a common heat pipe at different heights. be. The present invention has been devised in view of the above problems and to effectively solve them. Therefore, the objective is to provide a cooling system that allows appropriate flow control in each cooling unit even if the cooling units are installed at different height positions in a cooling system using gravity heat pipes. It is in.

[Means to solve the problem]

The cooling system according to the present invention has the following configuration in order to solve the problems of the prior art and achieve the objectives. In other words, a cold heat source device installed at a high place, and each cold heat source device installed at a lower place than the cold heat source device and connected by a gravity heat pipe corresponding to a plurality of cold heat source devices to one cold heat source device. a cooling unit; a liquid level detection means provided in a heat exchanger of the cooling unit for detecting the refrigerant liquid level in the heat exchanger at a predetermined height position and outputting a detection signal; A flow rate regulating valve is provided on a branch pipe of the pipe to each of the cooling units, and opens and closes the conduit of the branch pipe in response to an output signal from the liquid level detection means. Note that the gravity heat pipes have natural circulation force due to the phase change of the refrigerant, but they are not limited to means for circulating the refrigerant only by the natural circulation force; Of course, means for forcibly circulating the refrigerant, such as a pump, may be added to assist or to adjust the amount of refrigerant circulation.

[Effect]

In the cooling system according to the present invention, by installing the liquid level detection means at a desired position of the heat exchanger of the air conditioning unit, an appropriate liquid level of the refrigerant filled in the heat exchanger is set. . The liquid level detection means detects whether the refrigerant in the heat exchanger is at an appropriate liquid level or below the appropriate liquid level according to this set value,
The detection signal is output. This detection signal is output to control the opening and closing of the flow rate regulating valve provided in the branch pipe of the gravity heat pipe to the cooling unit.
When the refrigerant liquid level in the heat exchanger is appropriate, the flow control valve is closed to stop further refrigerant supply, and when the refrigerant liquid level is below the appropriate level, this valve is closed to supply refrigerant into the heat exchanger. Open the valve. Regarding the operation of opening the flow rate adjustment valve, it is common practice to output a valve opening command signal only when the refrigerant level in the heat exchanger drops below a predetermined limit, for example. The main objective of the invention is to suppress excessive supply of refrigerant when a large head pressure acts on the refrigerant, and to supply the refrigerant appropriately. Therefore, the liquid level at which the supply of refrigerant is stopped need only be set, and the liquid level at which the supply is started may be appropriately set in consideration of the evaporation rate of the refrigerant, etc. If the evaporation rate of the refrigerant is extremely slow, the flow rate regulating valve may be kept closed at all times, and the valve may be controlled to open when the liquid level is below an appropriate level. In this way, the supply or stop of supply of the refrigerant is controlled depending on the liquid level of the refrigerant, thereby constantly maintaining the refrigerant liquid level in the heat exchanger at an appropriate set value. Therefore, the head pressure of the refrigerant filled in the liquid system piping does not act on the refrigerant in the heat exchanger, and an appropriate liquid level can be maintained in any cooling unit regardless of the installation height of the cooling unit. The refrigerant in each cooling unit can be evaporated at the same temperature and pressure. Furthermore, it is easy to maintain the evaporation temperature of the refrigerant constant even if the heat load fluctuates. In addition, since a gravity heat pipe is used as the heat transfer means between the heat source device and the cooling unit, it is more effective than a cooling system using a direct expansion air conditioning system that uses a refrigerant such as fluorocarbon as a heat transfer medium, similar to the present invention. The refrigerating machine oil of the compressor does not mix with the refrigerant, and therefore there is no need to recover this refrigerating machine oil. In direct expansion type air conditioning systems, it is difficult to install too many air conditioning units in one unit due to constraints on recovering oil from the refrigeration machine.
However, depending on the conditions, the number of air conditioning units that can be connected to one condensing unit is usually limited to about five or six. On the other hand, in the present invention, by using a gravity heat pipe, the refrigerant sent to the cooling unit is separated from the compressor, and the restriction on refrigerating machine oil recovery is removed, so there is no restriction on the number of cooling units for the heat source device. . Furthermore, since the refrigerating machine oil to be recovered in a direct expansion air conditioning system is mixed in the refrigerant gas in the form of a mist, the flow rate of the refrigerant must be high to some extent in order to recover this refrigerating machine oil. Therefore, the throttling amount of the throttling mechanism cannot be increased very much, and as a result, the adjustment range of the cooling capacity becomes narrow. In contrast, in the present invention, there is no restriction on the flow rate of the refrigerant that affects the cooling capacity, and the cooling capacity can be adjusted in response to a wide range of variations in heat load.

【Effect of the invention】

As is clear from the above description, the present invention provides the following excellent effects. That is, in a cooling system using gravity heat pipes, even if each cooling unit is installed at a different height position, it is possible to appropriately control the flow rate in each cooling unit.

【Example】

Embodiments of the present invention will be described below with reference to FIGS. 1 to 5. FIG. 1 is a schematic configuration diagram schematically showing a building air conditioning system as an embodiment of the cooling system according to the present invention. Although the structure of the building is not shown in the diagram, the upper part of the diagram represents the higher part of the building. The cold/heat source device 1, which is installed at a high place in a building and cools the upper end of a gravity heat pipe, is composed of various devices described below. That is, a condensing unit 2 corresponding to an outdoor unit of an air conditioning unit is installed at a high place such as the roof of a building, and its evaporator is connected to a first evaporator 3 that directly cools a gravity heat pipe 12 and ice. A second evaporator 4 that cools the heat storage tank 5 is provided separately. The refrigerant flowing to the first evaporator 3 or the second evaporator 4 is switched to select one of the routes by the electromagnetic switching valves 6 and 7, and normally the second evaporator 4 is used at night. During the day, the first evaporator 3 is used to directly cool the gravity heat pipe 12. The ice heat storage tank 5 stores heat including about 80 times more latent heat than sensible heat, so it has a much larger heat storage capacity than a cold water heat storage tank that stores heat only by sensible heat. To obtain an ice heat storage tank with the same capacity as a heat storage tank, the size and weight can be much smaller than that of a cold water heat storage tank, and it can also be installed on a rooftop. The heat of the ice heat storage tank 5 is transferred to the gravity heat pipe 12.
Cooler 8 (gravity heat pipe 12
A pump 1 is installed on the way to circulate back and forth between the ice heat storage tank 5 (which functions as a condenser) and the ice heat storage tank 5.
It is pumped out by a cold water pipe system 9 configured with 0. Heat source devices that have both a heat storage system and a direct heat exchange system have been used in various other air conditioning systems, and the output ratio of each is changed as appropriate depending on the air conditioning load and heat storage capacity, especially during daytime operation. Also in this embodiment, the operation can be performed in the same manner as in the case of the conventional heat source device. In this way, the refrigerant in the gravity heat pipe 12 is cooled by the first evaporator 3 or the cooler 8, or by both, and is forced into circulation by the compressor 11 of the condensing unit 2. The refrigerant and the refrigerant that is naturally circulated by the gravity heat pipe 12 do not come into contact with each other and are separated from each other. In other words, the refrigerating machine oil in the compressor 11 does not mix with the refrigerant in the gravity heat pipe 12, and therefore each air conditioning unit 13a, which will be described later,
13b, . . . and can be easily recovered. On the other hand, each air conditioning unit 1 as a cooling unit
3a, 13b, . . . are various cold sources that cool the gravity heat pipe 12, such as when the various cold sources are installed on the roof of a building and are installed on each floor of the building. It is installed on the side of the air-conditioned room at a lower location than the equipment. The refrigerant in the gravity heat pipe 12 (solid line arrows in the figure indicate liquid flow, broken line arrows indicate gas flow) is cooled and condensed in the first evaporator 3 or cooler 8 on the cold heat source side, and then transferred to the liquid receiver. 17, it flows down inside the liquid system piping 18 from a high place to a low place, and flows to each air conditioning unit 13a, 13.
A branch pipe 19 branched to be supplied to b, ... and a flow rate regulating valve 22 interposed in this branch pipe 19
through the respective air conditioning units 13a, 13b,
It leads to... The liquid phase refrigerant that has flowed into each air conditioning unit 13a, 13b, ... is evaporated by exchanging heat in the heat exchanger 15 to cool the air in the air-conditioned room, and the gas in the gravity heat pipe 12 is It rises inside the system piping 20 and is refluxed to the cold heat source side. By the way, each air conditioning unit 13a, 13b,
... are commonly connected to the cold heat source side by one system of gravity heat pipes 12. Therefore, the inside of the liquid system piping 18 corresponding to the air conditioning unit 13a installed on the upper floor of the building and the air conditioning unit 13b installed on the lower floor is always kept in order to operate the air conditioning unit 13a on the upper floor. It is full of liquid. Therefore, even if a very large head pressure is not acting on the refrigerant flowing into the air conditioning unit 13a on the upper floor, a large water head pressure is acting on the refrigerant flowing into the air conditioning unit 13b on the lower floor. FIG. 2 is a schematic diagram showing the air conditioning unit in FIG. 1, a gravity heat pipe around it, and a refrigerant level control mechanism. A heat exchanger 15 is installed in the air conditioning unit 13 on the downstream side of the fan 16. The heat exchanger 15 is connected to a lower header 23 into which refrigerant flows from a branch pipe 19 of the liquid system piping 18 via a flow rate adjustment valve 22, and to the upper side of this lower header 23, and substantially constitutes a heat exchange section. a branch pipe 21 of the gas system piping 20 connected to the upper side of this coil part 25 and further above it.
The upper header 24 is connected to the upper header 24. Also, on the side of the heat exchanger 15, the heat exchanger 15
The communication pipe 26 shows a refrigerant liquid level equal to the refrigerant liquid level in the communication pipe 26.
is provided. In other words, this communication pipe 26 is
A branch pipe 19 of the liquid pipe 18 is connected to the lower end on the downstream side of the flow rate regulating valve 22, and a branch pipe 21 of the gas pipe 20 is directly connected to the upper end. Communication pipe 2
6 is attached with a liquid level control switch 27 that detects the liquid level of the refrigerant when it reaches a predetermined level and outputs a command signal to the flow rate regulating valve 22 to close it. That is, the communication pipe 26 and the liquid level control switch 27 constitute a liquid level detection means. The predetermined liquid level at which the liquid level control switch 27 outputs a command signal is a liquid level at which the refrigerant fills the coil portion 25 to a position slightly above the connection portion between the coil portion 25 and the upper header 24, and The liquid level is set at a height that does not immerse the connection portion between the upper header 24 and the branch pipe 21 of the gas system piping 20. Further, the flow rate adjustment valve 22 is connected to the air conditioning unit 1.
3 is not operated, that is, when the fan 16 is stopped, it is closed, and is closed when the fan 16 is in operation and the refrigerant level in the heat exchanger 15 is the level at which the above-mentioned command signal is output. However, if the intake air temperature, that is, the room temperature, is lower than the set temperature, it will be closed. 28 shown in Figures 2 and 3
is a temperature sensor that detects this intake air temperature. Although the heat exchanger 15 may be arranged obliquely as shown in FIG. 3, the communication pipe 26 and liquid level control switch 27 are provided in the same manner as in FIG. 2. In this way, each air conditioning unit 13a, 13b,
Even if there is a difference in the head pressure of the refrigerant due to the difference in the installation height of the refrigerant, each air conditioning unit 13
The refrigerant liquid level in the heat exchangers 15 of heat exchangers 15a, 13b, .
Since it is opened only when raising the liquid level of the refrigerant in the liquid system pipe 18 and closed at other times, the water head pressure of the refrigerant filled in the liquid system piping 18 is cut off by this valve. Therefore, which air conditioning unit 13a, 13
The refrigerant in the heat exchanger 15 has the same evaporation temperature under the same pressure in the cases b, . . . and can exhibit the same cooling capacity. Furthermore, the communication pipe 26, liquid level control switch 27, and flow rate adjustment valve 22 are connected to each air conditioning unit 1.
3a, 13b, . . . can be controlled independently. Furthermore, it goes without saying that the cooling capacity of each of the air conditioning units 13a, 13a, . . . or 13b, 13b, . In the above embodiment, the case where one air conditioning unit is each equipped with a liquid level control mechanism was explained, but as shown in FIG. 4, a plurality of air conditioning units 13 are installed at the same height on the same floor. In this case, if each air conditioning unit can be operated in the same operation mode, it is possible to consider these air conditioning units as one block and to control the liquid level of this one block by one liquid level control mechanism. That is, the communication pipe 26 and the liquid level control switch 27 control the opening and closing of the flow regulating valve 29 in units of blocks, and the opening and closing of the flow regulating valve 22 of each air conditioning unit 13 is controlled by the temperature sensor 28 of each air conditioning unit 13 itself. In the above embodiment, the case of a building air conditioning system was explained, but as a completely equivalent technical concept, an air conditioning unit as a cooling unit using a similar heat transfer system using a gravity heat pipe and a refrigerant liquid level control mechanism. It is also possible to use a refrigerator or freezer instead. FIG. 5 is a schematic configuration diagram schematically showing a refrigerator system in a housing complex such as an apartment as another embodiment of the cooling system according to the present invention. In the figure, 2' is the condensing unit, 3' is the evaporator (condenser for the gravity heat pipe 12') of the condensing unit 2', and the cold heat source device 1' is the condensing unit 2' and its evaporator. It is composed of a container 3'. 18' is a liquid system pipe, 20' is a gas system pipe, and 13' is a refrigerator as a cooling unit. In this case, each refrigerator 13' may not have a refrigerator and can be cooled only by the natural circulation cycle of refrigerant using a gravity heat pipe, or each refrigerator may be equipped with a small auxiliary refrigerator to cool the refrigerant. Cooling by a natural circulation cycle and cooling by a compression refrigeration cycle may be used together. In this case, when a refrigerator with a very small load is present, operation control is performed so that only the natural circulation cycle is operated and the auxiliary refrigerator is stopped. It can also be applied to refrigerated cases, refrigerators, and freezers in stores such as supermarkets. In this case,
Monthly and annual data such as load fluctuations due to objects to be cooled in the refrigerator and seasonal load fluctuations around the refrigerator are collected, and the cycles are stored in advance in a microcomputer, and the microcomputer operates the cooling and heat source equipment. It is also possible to control Furthermore, when an (ice) heat storage tank is provided on the cold heat source device side, it is also possible to use low-cost electricity at night for heat storage operation. Furthermore, even in the event of a power outage or failure of the cold/heat source device, the heat storage tank can be used for emergency operation, thereby increasing the reliability of the refrigeration system. Furthermore, by providing heat recovery means on the cold heat source device side, hot water supply equipment and heating equipment can also be used together. In the above-mentioned embodiments of the building air conditioning system and refrigeration system, an air conditioning unit or a refrigerator is installed as a cooling unit on each floor of the building. When supplying refrigerant liquid at the same pressure to the unit, or when the building is a high-rise building and there is a large difference in the refrigerant liquid supply pressure between the upper and lower floors, which poses a problem. By installing pressure reducing valves on each floor or every few floors in the horizontal refrigerant liquid pipes branched from the vertical refrigerant liquid pipes, the flow rate provided in the branch pipes from these horizontal refrigerant liquid pipes to each cooling unit can be reduced. Of course, the pressure applied to the regulating valve can be made equal or within an acceptable range.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram schematically showing a building air conditioning system as an embodiment of the cooling system according to the present invention, and Fig. 2 shows the air conditioning unit in Fig. 1, the surrounding gravity heat pipe, and the liquid level of the refrigerant. A schematic configuration diagram showing one embodiment of the control mechanism, FIG.
FIG. 4 is a schematic configuration diagram showing a modification of the refrigerant level control mechanism in the figure, FIG. 4 is a schematic configuration diagram schematically showing another embodiment of the building air conditioning system as a cooling system according to the present invention, and FIG. It is a schematic block diagram which shows typically the refrigerator system in housing complexes, such as an apartment, as another Example of the cooling system based on this invention. 1, 1'... Cold heat source device, 2, 2'... Condensing unit, 3... First evaporator, 3'... Evaporator, 4... Second evaporator, 5... Ice heat storage tank, 6 ,7
... Solenoid switching valve, 8 ... Cooler, 9 ... Cold water pipe system, 10 ... Pump, 11 ... Compressor, 1
2, 12'...Gravity heat pipe, 13, 13
a, 13b...Air conditioning unit as a cooling unit, 13'...Refrigerator as a cooling unit, 1
5... Heat exchanger, 16... Fan, 17... Liquid receiver, 18... Liquid system piping, 19... Branch pipe thereof, 2
0... Gas system piping, 21... Its branch pipe, 22...
...Flow rate adjustment valve, 23...Lower header, 24...Upper header, 25...Coil part, 26...Communication pipe,
27...Liquid level control switch, 28...Temperature sensor, 29...Flow rate adjustment valve for each block.

Claims (1)

[Claims] 1 Cold heat source devices 1, 1' installed at a high place, and one cold heat source device 1, 1' installed at a lower place than the cold heat source devices 1, 1'. On the other hand, each cooling unit 13, 13a, 13b, ..., 1 connected by gravity heat pipe 12, 12' corresponds to multiple units.
3', and the cooling units 13, 13a, 13b,..., 1
3' heat exchanger 15, the heat exchanger 15
liquid level detection means 26, 2 for detecting the refrigerant liquid level in the refrigerant at a predetermined height position and outputting a detection signal thereof;
7, and each cooling unit 13, 13a, 13b,..., 13' of the gravity heat pipe 12, 12'.
The liquid level detection means 2 is provided in a branch pipe 19 to
6 and 27. A cooling system comprising a flow rate regulating valve 22 that opens and closes the branch pipe 19 in response to output signals from the branch pipes 6 and 27. 2 Each of the cooling units 13, 13a, 13b,
. . , 13' are the cooling system according to claim 1, wherein the installation height positions are different from each other. 3. The heat exchanger 15 includes a lower header 23, a coil section 25, and an upper header 24, and the liquid level detection means 26, 27 detect the liquid level of the liquid refrigerant at a height position in the upper header 24. The cooling system according to claim 1 or 2, wherein the cooling system detects that the flow rate adjustment valve 22 is present and outputs a detection signal to close the flow rate regulating valve 22.