JP2530486B2 - Refrigerant natural circulation type cooling system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention connects a cooling condenser and a cooling heat exchanger of an individual air conditioner provided on each floor through a refrigerant pipe, A cooling condenser and the cooling heat exchanger and a refrigerant pipe are configured to circulate and circulate the refrigerant in a hermetically sealed state, and, as the refrigerant, with heat exchange in the cooling heat exchanger, a liquid While using the cooling refrigerant for phase change from to vapor, between the cooling condenser and the cooling heat exchanger, to transfer the cooling refrigerant that has changed to a liquid phase to the cooling heat exchanger The present invention relates to a refrigerant natural circulation type cooling system having a sufficient head difference.

<Prior Art> A conventional refrigerant natural circulation type cooling system of this type is as follows.

A. First Conventional Example FIG. 7 is a system configuration diagram of the first conventional example, in which the cooling heat exchanger 02 and the cooling condenser 03 of the individual air conditioner 01 provided on each floor are the refrigerant pipes 04. Is connected to each other via a flow control valve 05 at the inlet or outlet of the refrigerant pipe 04, and at the outlet of the refrigerant pipe 04 from the cooling heat exchanger 02, the temperature of the refrigerant therein is adjusted. A temperature sensor 06 for sensing is provided, and based on the temperature sensed by the refrigerant temperature sensor 06, the refrigerant temperature sensor
When the temperature sensed by 06 is higher than the set temperature, the flow control valve 05 is opened to increase the amount of the refrigerant liquid supplied to the cooling heat exchanger 02, while the temperature sensed by the refrigerant temperature sensor 06 is set. When the temperature is lower than the temperature, the flow control valve 05 is opened to reduce the amount of the refrigerant liquid supplied to the cooling heat exchanger 02 so that the temperature sensed by the refrigerant temperature sensor 06 always maintains the set temperature. The flow rate control valve 05 is controlled so that the temperature of the air blown out from the individual air conditioner 01 is maintained constant.

In addition, according to the first conventional example, the refrigerant temperature sensor indicates that the refrigerant liquid has reached the outlet from the cooling heat exchanger 02.
Because it can be detected by 05, a plurality of individual air conditioners 01 are juxtaposed on each floor, and when a difference occurs in the cooling loads between the juxtaposed individual air conditioners 01, 01, one cooling load The advantage is that it is possible to prevent the occurrence of so-called liquid back, in which the refrigerant liquid flows from the cooling heat exchanger 02 on the smaller side to the cooling heat exchanger 02 on the larger cooling load side.

B. Second Conventional Example Similar to the first conventional example, an electromagnetically operated on-off valve 07 is provided at the inlet of the refrigerant pipe 04 to the cooling heat exchanger 02, and is parallel to the cooling heat exchanger 02. The refrigerant pipe 04 is connected to the level detection pipe 08, and the level detection pipe 08 is connected to the level detection pipe 08.
A liquid level sensor 09 for detecting the level of the refrigerant liquid in the pipe is provided, and the on-off valve 07 is controlled so that the liquid level level detected by the liquid level sensor 09 is maintained at a set level. It is configured so that the temperature of the air blown from the machine 01 is maintained constant.

<Problems to be Solved by the Invention> However, according to the above-mentioned conventional examples, there are the following drawbacks.

a. Disadvantage of the first conventional example In this type of refrigerant, when the temperature change in the vapor state is small and the temperature sensed by the refrigerant temperature sensor 06 changes, the sensing point by the refrigerant temperature sensor 06, or This is the case where the refrigerant liquid has risen to a location close to it, and a refrigerant temperature sensor for temperature changes in the space to be cooled.
06 does not follow the sensed temperature well, and in reality, it is not controlled even if the temperature of the air blown out through the cooling heat exchanger 02 is much lower than the desired temperature. There was a drawback that could not be done.

Also, the sensing point by the refrigerant temperature sensor 06, or
As a result of the change in the temperature sensed by the refrigerant temperature sensor 06 due to the rise of the refrigerant liquid to a position close to it, the refrigerant temperature is controlled even though the flow control valve 05 is not controlled by the normal temperature change in the space to be cooled. When the temperature sensed by the sensor 06 has reached a temperature sufficient to change, the opening degree of the flow control valve 05 is controlled to decrease, and when the opening degree is decreased, the temperature sensed by the refrigerant temperature sensor 06 also rapidly increases. On the contrary, this time, on the contrary, the opening degree of the flow rate control valve 05 is controlled so as to increase, and as a result, the temperature sensed by the refrigerant temperature sensor 06 suddenly decreases and the flow rate control valve 05 is controlled. The flow control valve 05 is repeatedly turned on and off, causing hunting in the temperature of air blown out from the cooling heat exchanger 02 to cause discomfort.

b. Disadvantages of the second conventional example Since there is a difference between the flow resistance to the refrigerant in the cooling heat exchanger 02 and the flow resistance to the refrigerant in the level detection pipe 08, when the on-off valve 07 is opened for control. , A large amount of the refrigerant liquid flows to the side with a small resistance, and the actual refrigerant liquid level and the liquid level in the level detection tube 08 are different,
For example, if the resistance on the level detection tube 08 side is smaller, most of the refrigerant liquid rapidly flows into the level detection tube 08 side as the opening / closing valve 07 is opened, and the liquid level sensor 09 senses it. Even if the on-off valve 07 is closed, the level of the refrigerant liquid on the cooling heat exchanger 02 side is low, and the refrigerant liquid on the level detection pipe 08 side flows into the cooling heat exchanger 02 side, and accordingly, the level detection pipe. 08
The level of the refrigerant liquid on the side becomes lower than the set level, and the opening / closing valve 07 is opened again. As a result, the opening / closing valve 07
Since the temperature of the blown air is controlled while frequently opening and closing 07, it is not possible to perform highly accurate control, and there is a drawback that hunting occurs and discomfort occurs.

The first refrigerant natural circulation type cooling system according to the present invention,
In view of such circumstances, by changing the set temperature in accordance with the degree of load variation in the space to be cooled, the set temperature can be quickly returned to and a comfortable cooling operation can be performed. The second refrigerant natural circulation type cooling system according to the present invention aims to ensure that the temperature of the blown air blown through the cooling heat exchanger reaches the set temperature. It is an object of the present invention to perform temperature control with high accuracy and to perform a more comfortable cooling operation.

<Means for Solving the Problem> The first refrigerant natural circulation type cooling system according to the present invention is
In order to achieve the above-mentioned target, in the refrigerant natural circulation type cooling system described at the beginning, a flow rate control valve which is provided at the inlet of the refrigerant pipe to the cooling heat exchanger and which regulates the refrigerant liquid inflow amount, Based on the room temperature sensor that senses the temperature of the space to be cooled, and the temperature sensed by the room temperature sensor, set the sensed temperature by operating the flow control valve so that the opening becomes larger as the sensed temperature becomes higher than the set temperature. The first control means for maintaining the temperature and the set temperature such that the set temperature is lower when the temperature sensed by the room temperature sensor is higher than the reference set temperature, and the set temperature is higher when the sensed temperature is lower than the reference set temperature. And a setting temperature changing means for automatically changing the temperature.

A second refrigerant natural circulation type cooling system according to the present invention is, in addition to the first refrigerant natural circulation type cooling system, blown air blown from a cooling heat exchanger in order to achieve the above-mentioned object. Second control means for operating a flow rate control valve so that a blown air temperature sensor for sensing the temperature of the blown air is provided, and the sensed temperature of the blown air by the blown air temperature sensor becomes the set temperature set by the set temperature changing means. And is configured.

<Operation> According to the configuration of the first refrigerant natural circulation type cooling system according to the present invention, based on the temperature of the cooled space sensed by the room temperature sensor, the sensed temperature and the reference set temperature are compared,
The higher the reference set temperature, the lower the set temperature, or the lower the reference set temperature, the higher the set temperature. The higher the sensed temperature, the larger the opening. The opening degree of the flow control valve is controlled so that a large amount of refrigerant liquid is supplied to the cooling heat exchanger when the cooling load in the cooled space is large, while a small amount of the refrigerant liquid is supplied when the cooling load in the cooled space is small. Is supplied to the cooling heat exchanger to quickly return the temperature sensed by the room temperature sensor to the set temperature in response to fluctuations in the cooling load in the space to be cooled, and maintain the set temperature or a temperature close to it. can do.

Further, according to the configuration of the second refrigerant natural circulation type cooling system according to the present invention, as described above, the opening degree of the flow control valve is controlled by the first control means to the cooling heat exchanger. The inflow amount of the refrigerant liquid is adjusted, the actual temperature of the blown air is sensed by the blown air temperature sensor, and the second control means controls the opening degree of the flow rate control valve based on the sensed temperature to control the heat exchange for cooling. It is possible to adjust the inflow amount of the refrigerant liquid into the container and control so that the actual temperature of the blown air becomes the set temperature.

<Example> Hereinafter, an example of the present invention is described in detail based on a drawing.

FIG. 1 is an overall system configuration diagram showing an embodiment of a refrigerant natural circulation type cooling system according to the present invention, and FIG. 2 is an enlarged configuration diagram of essential parts.

In these figures, A is a heat source installed on the roof of a building B, and includes an ice maker 1 for producing fine ice and a heat storage tank 2 for supplying and storing fine ice obtained by the ice maker 1. It is composed of

A cooling condenser 3 is installed on the roof of the building B, and the cooling condenser 3 and the heat storage tank 2 are connected to each other through a circulation pump 4 to cool the cold water stored in the heat storage tank 2 into a cooling condenser. 3 is circulated and supplied.

On the other hand, in each room on each floor F of the building B, etc., a blower fan 5, a cooling heat exchanger 6 and a heating heat exchanger 7 are provided.
An individual air conditioner 8 having the above is provided.

The cooling condenser 3 and the cooling heat exchanger 6 are connected to each other through a cooling receiver 9 and a cooling refrigerant pipe 11 having cooling headers 10 and 10, and at the same time, Along with the heat exchanger 3 for cooling, the heat exchanger 6 for cooling, and the refrigerant pipe 11 for cooling, a phase change from liquid to vapor is accompanied by heat exchange in the heat exchanger 6 for cooling, and condensation in the condenser 3 for cooling is performed. Due to this, the cooling medium that changes its phase from vapor to liquid is sealed in a sealed state.

The cooling liquid receiver 9 is installed at a position higher than each of the cooling heat exchangers 6 ..., and the cooling refrigerant that has been phase-changed from the above into a liquid by the condensation in the cooling condenser 3 is the cooling heat exchanger. 6 is provided with a head difference enough to allow the cooling refrigerant that has been phase-changed from liquid to vapor due to heat exchange in the cooling heat exchanger 6 to rise and be returned to the cooling condenser 3. Thus, during the cooling operation, the cooling refrigerant is cooled by the phase change between the vapor and the liquid, and the cooling condenser 3 and the cooling heat exchanger 6 are discharged.
It is configured to naturally circulate between and.

Also, a heating evaporator 12 is installed in the basement of Building B,
The heating evaporator 12 is configured to be supplied with hot water generated in the ice maker 1.

The heating evaporator 12 and the heating heat exchanger 7 are connected to each other via a heating liquid receiver 13 and a heating refrigerant pipe 15 in which heating headers 14 and 14 are interposed, and heating is performed. Along with the heat exchanger 12 for heating, the heat exchanger 7 for heating, and the refrigerant pipe 15 for heating, a phase change from liquid to vapor is accompanied by heat exchange in the evaporator 12 for heating, and at the heat exchanger 7 for heating. A heating refrigerant that changes from vapor to liquid due to condensation is sealed in a sealed state.

The liquid receiver 13 for heating is arranged at a position lower than the heat exchanger 7 for heating, and the refrigerant for heating that has been phase-changed from vapor to liquid due to condensation in the heat exchanger 7 for heating is an evaporator for heating. While being supplied to the heating evaporator 12, the heating refrigerant that has been phase-changed from liquid to vapor due to heat exchange in the heating evaporator 12 rises and is returned to the heating heat exchanger 7 ... The heating refrigerant is provided with the heating heat exchanger 7 and the heating evaporator 12 by the phase change between the vapor and the liquid during the heating operation.
It is configured to naturally flow between and.

Freon gas R-22 is used as each of the cooling refrigerant and the heating refrigerant. This has the advantage that it does not destroy the ozone phase because it contains hydrogen and chlorine and decomposes in the troposphere.

A cooling flow rate control valve 16 for adjusting the refrigerant liquid inflow amount is provided at the inlet of each cooling heat exchanger 6 of the cooling refrigerant pipe 11.

Individual air conditioner 8 ... A room temperature sensor 17 for detecting the temperature of the return air to the individual air conditioner 8 as the temperature of the space to be cooled is attached to each air intake point to each cooling heat exchanger 6, and A liquid detection sensor 18 for detecting a refrigerant liquid and outputting a liquid detection signal is attached to an outlet of each of the cooling heat exchangers 6 of the cooling refrigerant pipe 11. The room temperature sensor 17 may be provided in the space to be cooled and configured to sense the temperature in the space to be cooled.

In addition, a heating flow control valve 19 for adjusting the amount of the refrigerant vapor inflow is attached to each of the heating refrigerant exchanger 15 ... A check valve 20 for preventing backflow is attached to the side.

An individual air conditioner 8 ... A blown air temperature sensor 12 for detecting the temperature of the blown air is attached to each of the blown air points.

A control device 22 is provided for each individual air conditioner 8 ... And a room temperature sensor 17, a liquid detection sensor 18, and a blown air temperature sensor 21 are connected to the control device 22.

As shown in the block diagram of FIG. 3, the control device 22 includes a CPU 23, a ROM 24 and a RAM 25, and the room temperature sensor 1
7. The signals from the liquid sensor 18 and the blown air temperature sensor 21 are input through the input interface circuit 26.
While being input to the CPU 23, the command signal from the CPU 23 is output to the cooling flow control valve 16 or the heating flow control valve 19 via the output interface circuit 27.

In the CPU 23, as shown in the block diagram of FIG.
A set temperature changing means 28, a first control means 29, a second control means 30, and a third control means 31 are provided.

The set temperature changing means 28 automatically sets the set temperature so that the set temperature is lower as the temperature sensed by the room temperature sensor 17 is higher than the reference set temperature, and the set temperature is higher as the sensed temperature is lower than the reference set temperature. It is supposed to be changed.

The first control means 29 comprises a first comparing means 32 and a first pulse number calculating and generating means 33, and the room temperature sensor 17
The sensed temperature is higher than the set temperature by comparing the sensed temperature with the set temperature and outputting the number of open side or close side drive pulses according to the temperature difference between the two based on the comparison result to the flow control valve 16. Flow control valve so that the opening becomes larger
16 is activated to maintain the sensed temperature at the set temperature.

The second control means 30 comprises a second comparing means 34 and a second pulse number calculating and generating means 35, and detects the temperature sensed by the blown air temperature sensor 21 and the set temperature set by the set temperature changing means 28. The output pulse is output to the flow control valve 16 by a number corresponding to the temperature difference between the two based on the comparison result, and the opening becomes larger as the sensed temperature becomes higher than the set temperature. Thus, the flow control valve 16 is operated to maintain the sensed temperature at the set temperature.

The third control means 31 is composed of a liquid presence / absence determining means 36 and a constant pulse number generating means 37, and operates the flow rate control valve 16 to the closing side in response to the liquid detection signal from the liquid detection sensor 18. A constant number of drive pulses are output to close the flow rate control valve 16 by a predetermined opening. The number of pulses output here is, for example, about 10 when the number of pulses driving from the fully closed state to the fully open state is 200, and the number of pulses to be closed is 0.5% each.

Further, the cooling / warming switching means 38 is interposed between the first control means 29 and the cooling flow control valve 16, and during the heating operation,
The signal from the first pulse number calculation generating means 33 is switched to be output to the heating flow control valve 19, and the first control means 29 is switched.
Is used to control the temperature during the heating operation.

Next, the operation of the CPU 23 will be described with reference to the flowchart of FIG.

First, whether the blower fan 5 is activated, that is,
It is determined whether or not the cooling operation is being performed (S1). If the cooling operation is not being performed, the process proceeds to step S2, the cooling flow control valve 16 is fully closed, and then the process returns to step S1.

When it is determined that the cooling operation has started in step S1, the process proceeds to step S3, based on the signal from the liquid detection sensor 18, it is determined whether or not the liquid is detected by the liquid presence / absence determining unit 36, and the liquid is detected. For example, the process proceeds to step S4, it is determined whether the cooling flow control valve 16 is in the fully closed state, and if it is in the fully closed state, step S1 is performed to wait for the evaporation of the refrigerant liquid.
Return to. On the other hand, if the cooling flow control valve 16 is not in the fully closed state, the process proceeds to step S5 to output a fixed number of pulses to close the cooling flow control valve 16 by a predetermined opening degree in order to prevent hunting. After waiting for a time in step S6 until the closed state of the predetermined opening is obtained, the process returns to step S1. The operations from step S3 to step S6 are performed by the above-mentioned third control means 31.

In step S3, if the liquid is not sensed,
In order to prevent hunting, wait for time in step S7, then move to step S8, input the temperature signal T _i from the room temperature sensor 17, and set the temperature based on the temperature signal T _i and the reference set temperature. The set temperature T is calculated by the changing means 28 (S9).

The calculation of the set temperature T by the set temperature changing means 28 is
It is performed by proportional calculation based on the characteristic diagram specified in advance shown in FIG. That is, in this figure, the horizontal axis represents the temperature signal T _i from the room temperature sensor 17, while the vertical axis represents the set temperature for the blown air, and the room temperature sensor 17
The change width of the set temperature is doubled with respect to the change width of the temperature signal T _i (each ΔT ₂ and ΔT ₂ shown in the figure is 2 ° C.), and ΔT ₁ shown in the figure is 8 ° C. Reference set temperature SP and room temperature sensor of return air to individual air conditioner 8
The difference (SP−T _i ) from the temperature T _i sensed in 17 is taken, and the set temperature T for the blown air is T = X ₁ + 4 + 2 × (based on the lower limit value X ₁ of the set temperature for the blown air. It is calculated as SP-T _i ).

Reference temperature SP of return air to the individual air conditioner 8
Is normally set at 26 ° C.

Then, the process proceeds to step S10, and compares the temperature T _i and the set room temperature T _o sensed by the temperature sensor 17, is lower than the sensing room temperature T _i is set room temperature T _o, the cooling flow control valve at the step S11 Step S1 after confirming that 16 is not in the fully closed state
2, the first pulse number calculation generating means 33 calculates the pulse number proportional to the temperature difference (T _o −T _i ), and the drive pulse signal of the calculated pulse number is supplied to the flow control valve 16
To reduce the opening degree of the flow control valve 16.

On the other hand, higher than the sensed room temperature T _i is set room temperature T _o, and transition from Confirm that cooling flow control valve 16 in step S13 is not fully opened in step S14, the first pulse number calculating generating means 33 Thus, the pulse number proportional to the temperature difference (T _i −T _o ) is calculated, and the drive pulse signal of the calculated pulse number is output to the flow rate control valve 16 to increase the opening degree of the flow rate control valve 16.

In step S11, when it is determined that the cooling flow control valve 16 is fully closed, and when it is determined in step S13 that the cooling flow control valve 16 is fully open, any further Since the control of No. cannot be performed, the process returns to step S1. The operation from step S10 to step S14 is performed by the above-mentioned first control means 29.
Done by

After step S12 or step S14,
In step S15, the temperature t _{i of the} blown air detected by the blown air temperature sensor 21 is input, and the blown air temperature t _i is compared with the set temperature T for the blown air calculated in step S9 described above. (S16), it is lower than blowoff air temperature t _i is the set temperature T, the step
The process proceeds to S17, and the second pulse number calculation / generation means 35
The number of pulses proportional to the temperature difference (T−t _i ) is calculated, and the drive pulse signal of the calculated number of pulses is sent to the flow control valve 16
To reduce the opening degree of the flow control valve 16.

On the other hand, if the blown air temperature t _i is higher than the set temperature T, the process proceeds to step S18, and the second pulse number calculation and generation means 35 calculates the number of pulses proportional to the temperature difference (t _i −T). The drive pulse signal of the calculated pulse number is output to the flow control valve 16 to increase the opening degree of the flow control valve 16. The operations from step S15 to step S18 are performed by the second control means 30 described above.

By repeating the above operation, even if the cooling load in the air-conditioned space suddenly fluctuates, the temperature can be quickly returned to the temperature according to the set temperature and comfortable cooling can be performed. .

Although not shown, in the heating operation, the first
It is controlled by a control means corresponding to the control means 29.

The lower limit value X ₁ of the set temperature of the blown air is adapted to be calculated each time based on the temperature of the blown air which is the result of control through the second control means 30, and by this learning function, More precise control can be performed.

In this embodiment, the set temperature for the blown air is changed by the set temperature changing means 28, and the field back control is performed by comparing the set blown air temperature and the temperature sensed by the blown air temperature sensor 21, but, for example, The set temperature changing means 28 may be configured to change the set temperature for the return air.

Further, according to the present invention, an absorption refrigerator is used as the heat source A, and cold water, low-temperature refrigerant, or the like from the absorption refrigerator is supplied to the cooling condenser 3, or a district cooling and heating system is used. Therefore, various types can be adopted, such as a configuration in which the cold water obtained is supplied to the cooling condenser 3.

Further, in the above embodiment, the system is configured to perform both cooling and heating, but the present invention may be configured to a system dedicated to cooling.

<Effects of the Invention> According to the refrigerant natural circulation type cooling system according to the present invention,
The higher the temperature sensed by the room temperature sensor with respect to the reference set temperature, the lower the set temperature, and conversely, the higher the temperature with respect to the reference set temperature, the higher the set temperature. The set temperature itself is automatically changed according to the degree of fluctuation, and the opening of the flow control valve is controlled so that the opening becomes larger as the sensed temperature becomes higher than the set temperature. The temperature sensed by the room temperature sensor can be quickly returned to the set temperature in response to load fluctuations, and the temperature in the cooled space can be quickly returned to the set temperature regardless of fluctuations in the cooling load in the cooled space. , It is possible to maintain the set temperature and perform comfortable cooling operation.

Then, according to the second refrigerant natural circulation type cooling system of the present invention, the actual temperature of the blown air, which is the result of the control by the first control means, is detected by the blown air temperature sensor, and the second temperature is detected based on the detected temperature. By adjusting the amount of the refrigerant liquid flowing into the cooling heat exchanger by the control means, the actual temperature of the blown air is controlled to be the set temperature.
Immediately judging the suitability of the control result and controlling again to correct it, the temperature in the space to be cooled can be returned to the set temperature more quickly, and the cooling operation can be performed more comfortably. Is now possible.

[Brief description of drawings]

The drawings show an embodiment of a refrigerant natural circulation type cooling system according to the present invention. FIG. 1 is an overall system configuration diagram, FIG. 2 is an enlarged configuration diagram of essential parts, and FIGS. Each is a block diagram, FIG. 5 is a flow chart for explaining the operation of the CPU, FIG. 6 is a characteristic diagram, FIG. 7 is a system configuration diagram of the first conventional example, and FIG. 8 is a system configuration diagram of the second conventional example. is there. 3 ... Cooling condenser 6 ... Cooling heat exchanger 8 ... Individual air conditioner 11 ... Cooling refrigerant piping 16 ... Cooling flow control valve 17 ... Room temperature sensor 21 ... Blow-off air temperature sensor 28 ...... Set temperature changing means 29 ...... First control means 30 ...... Second control means F ...... Each floor

Front page continued (72) Kenji Komiyama, Kenji Komiyama 4-27, Honmachi, Higashi-ku, Osaka City, Osaka Incorporated company Takenaka Corporation Osaka Main Store (72) Inventor, Isao Tachibana 4-27, Honmachi, Higashi-ku, Osaka Takenaka Corporation Osaka Main Store (56) Reference JP-A-49-19442 (JP, A) JP-A-63-118546 (JP, A) JP-A-1-159554 (JP, A)

Claims (2)

(57) [Claims] 1. A cooling condenser and a cooling heat exchanger of an individual air conditioner provided on each floor are connected in communication through a refrigerant pipe, and the cooling condenser, the cooling heat exchanger and a refrigerant are connected. It is configured to circulate and circulate the refrigerant in a hermetically sealed state over the pipe, and, as the refrigerant, while using a cooling refrigerant for phase change from liquid to vapor with heat exchange in the cooling heat exchanger, Between the cooling condenser and the cooling heat exchanger, a refrigerant natural circulation type cooling system having a head difference sufficient to transfer the cooling refrigerant that has been phase-changed to a liquid to the cooling heat exchanger, A flow rate control valve that is provided at the inlet of the refrigerant pipe to the cooling heat exchanger to adjust the amount of refrigerant liquid inflow, a room temperature sensor that senses the temperature of the space to be cooled, and a temperature sensed by the room temperature sensor. , The sensed temperature is set The higher becomes higher degree than degrees is maintained at the set temperature sensed temperature by operating the flow control valve such that the large-1
And the set temperature is automatically changed so that the temperature detected by the room temperature sensor is higher than the reference set temperature, the set temperature is lower, and the sensed temperature is lower than the reference set temperature, the set temperature is higher. A cooling medium natural circulation type cooling system, comprising: 2. The refrigerant natural circulation cooling system according to claim 1, further comprising a blow-out air temperature sensor for detecting a temperature of blow-out air blown out from the cooling heat exchanger, A refrigerant natural circulation type cooling system comprising second control means for operating the flow rate control valve so that the temperature sensed by the temperature sensor of the blown air becomes the set temperature set by the set temperature changing means.