JP2015210011A - Natural circulation type cooling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately eliminate gas occurring in a refrigerant liquid feeding pipe line in startup to attain smooth operation, in a natural circulation type cooling device that utilizes the elevation difference between a heat exchanger for air conditioning and a condenser to naturally circulate refrigerant.SOLUTION: A condenser 3 is arranged at a higher place than a heat exchanger 2 for air conditioning, and they are connected by a refrigerant gas return pipe line 6 and a refrigerant liquid feeding pipe line 7. In the refrigerant liquid feeding pipe line 7, an expansion valve 13 is arranged in the vicinity of the heat exchanger 2 for air conditioning. A bypass passage 14 is connected in a state of straddling the expansion valve 13, and a relief valve 15 is provided in the bypass passage 14. When a pressure sensor 16 detects excessive low pressure of the refrigerant liquid feeding pipe line 7, gas is discharged to the side of the heat exchanger 2 for air conditioning by opening the relief valve 15. Since gas is discharged in the dedicated bypass passage 14, gas is rapidly and surely discharged.

Description

  The present invention relates to a natural circulation type cooling device that circulates a refrigerant without power using a difference in height between an air conditioning heat exchanger and a condenser.

  In the natural circulation type cooling device, a refrigerant having a low vaporization temperature (boiling point) such as chlorofluorocarbon is used, and the condenser is disposed at a position higher than the heat exchanger for air conditioning (indoor unit). Liquid refrigerant (refrigerant liquid) flows from the condenser to the air conditioning heat exchanger by gravity, and the refrigerant (refrigerant gas) evaporated through the air conditioning heat exchanger passes through the refrigerant gas return line because it is lighter than air. Then, the refrigerant gas is returned to the condenser, and the refrigerant gas is cooled by the condenser and returned to the refrigerant liquid to repeat the circulation from the refrigerant liquid feed line to the air conditioning heat exchanger. An electromagnetic expansion valve or the like is provided at the lower end of the refrigerant liquid feed line, and the cooling temperature is adjusted by adjusting the opening of the expansion valve.

  The condenser is generally water-cooled, and the refrigerant gas is liquefied by bringing the refrigerant gas into contact with a narrow tube through which the cooling water passes. In a natural circulation type cooling device, the operation is started by passing the cooling water through the condenser. Due to the lower internal pressure of the condenser, gas (forming gas, flash gas) may be generated in the lower part of the refrigerant liquid feed line.

  And if gas is discharged | emitted by the heat exchanger for an air conditioning, a pressure difference will almost disappear on both sides which pinched | interposed the expansion valve, and it will become impossible to exhibit a cooling function without circulating a refrigerant | coolant. In addition, by stopping some of the air conditioning heat exchangers in equipment equipped with a plurality of air conditioning heat exchangers, the capacity of the condenser relative to other air conditioning heat exchangers can be relatively increased. Gas may be generated in the refrigerant liquid feed pipe, and in this case, natural circulation may be stopped or suppressed. Further, gas may be generated in the refrigerant liquid feed line due to the shutdown of the cooling device.

  Therefore, it is considered to remove the gas generated in the refrigerant liquid feed line at the time of starting or the like. As an example, Patent Document 1 discloses that an electromagnetic valve is provided upstream of the expansion valve in the refrigerant liquid feed line. It is disclosed that when the pressure difference between the refrigerant gas return line and the refrigerant liquid feed line drops to a predetermined value, the solenoid valve is fully opened to discharge the gas to the air conditioning heat exchanger.

  On the other hand, Patent Document 2 discloses that the gas is discharged to the refrigerant gas return pipe by controlling the opening degree of the expansion valve. Further, Patent Documents 3 and 4 disclose that the gas accumulated in the refrigerant liquid feed line is discharged to the refrigerant gas return line by opening the expansion valve when the operation of the cooling device is stopped. ing.

JP-A-7-151353 JP 2005-337540 A JP 2000-292025 A JP 2005-308302 A

  In Patent Documents 1 and 2, the generation of gas is unavoidable and gas is released. However, in any case, the gas escapes to the heat exchanger for air conditioning (indoor unit) through the expansion valve. Depends on the opening of the expansion valve, but since the expansion valve adjusts the flow rate of a small amount of liquid, it is impossible to escape a large amount of gas at a stretch, and it takes time to exhaust the gas. Therefore, there is a problem that the cooling rise is slow.

  On the other hand, Patent Documents 3 and 4 have a problem that even if the gas generated by the operation stop can be excluded, the gas generated by starting cannot be excluded.

  The present invention has been made to improve the current situation.

  The natural circulation type cooling device of the present invention includes an air conditioning heat exchanger that cools by evaporating in the process of passing the refrigerant, and a condenser that is disposed at a higher position than the heat exchanger, The outlet of the heat exchanger and the inlet of the condenser are connected by a refrigerant gas return line, and the inlet of the heat exchanger for air conditioning and the outlet of the condenser are connected by a refrigerant liquid feed line, This is a basic configuration in which an expansion valve is provided in a portion of the liquefied refrigerant feed line near the heat exchanger for air conditioning.

  The present invention includes many characteristic configurations under the basic configuration described above, and typical examples thereof are specified in the respective claims. Among these, in the first aspect of the present invention, a bypass is provided for letting the gas generated in the refrigerant liquid feed pipe to the downstream side of the expansion valve 13 at the lower end portion of the refrigerant liquid feed pipe and upstream of the expansion valve. A passage is connected, and a relief valve that opens when the pressure in the vicinity of the upstream side of the expansion valve drops below a preset pressure is provided in the bypass passage.

  According to a second aspect of the present invention, in the first aspect, the bypass passage is connected to both sides of the lower end portion of the refrigerant liquid feed pipe with the expansion valve interposed therebetween. Further, the invention of claim 3 is the invention according to claim 1 or 2, wherein the lower part of the refrigerant liquid feed line is a portion upstream of the expansion valve and close to the expansion valve, or of the bypass passage. Pressure detection means is provided upstream of the relief valve, and the opening and closing of the relief valve is controlled based on the pressure detection means.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, the bypass passage is disposed in a substantially horizontal posture, and a fifth aspect of the invention is directed to any one of the first to fourth aspects. In this case, the relief valve is of a drain trap type that allows gas to pass but does not allow or hardly pass liquid. On the other hand, the invention of claim 6 is the type according to any one of claims 1 to 4, wherein the relief valve is of a type that allows gas and liquid to pass through, and the expansion valve is fully closed when the relief valve is open. Or it is narrower than the normal operating state.

  The air-conditioning heat exchanger of the present invention can use a fan coil type, but in the invention of claim 7, the air-conditioning heat exchanger comprises a radiant cooling panel in which a refrigerant channel is provided on a heat conductive substrate. Yes.

  In the present invention, the gas generated in the refrigerant liquid feed pipe is discharged to the downstream side of the expansion valve by a dedicated bypass passage. For this reason, the state where the refrigerant liquid feed line is filled with the liquid refrigerant can be realized at an early stage by quickly removing the gas. As a result, the conditions for the natural circulation of the refrigerant can be adjusted early, and the cooling cycle can be quickly started.

  The outlet of the bypass passage can be connected, for example, to a refrigerant gas return pipe or to a condensation tank. In this case, the length of the bypass passage becomes longer, which increases costs and increases weight. Problems may arise. On the other hand, if the inlet and outlet of the bypass passage are connected near the expansion valve as in the second aspect, the length of the bypass passage can be made as short as possible to contribute to cost and weight reduction.

  Further, in claim 2, since the refrigerant leaking from the bypass passage flows through the heat exchanger for air conditioning regardless of whether it is in a gas state or a liquid state, gas remains in the bypass passage. There is no particular problem, and there is an advantage that the rise of the cooling can be promoted by flowing the liquid refrigerant through the heat exchanger for air conditioning.

  If the structure of Claim 3 is employ | adopted, since the pressure of the site | part close | similar to an expansion valve can be reflected in the action | operation of a relief valve, the responsiveness of the action | operation of the relief valve with respect to generation | occurrence | production of gas can be improved. As a result, there is an advantage that the gas can be eliminated at an early stage and the smooth start-up of the cooling can be further ensured.

  In addition, when the configuration of claim 4 is adopted, it is possible to accurately prevent the gas from accumulating in the bypass passage, so that the gas accumulated in the bypass passage after closing the relief valve escapes to the heat exchanger for air conditioning and the vapor lock phenomenon is prevented. It is possible to eliminate problems that may occur.

  If a drain trap type valve is used as a relief valve, liquid refrigerant can be prevented from being excessively supplied to the air-conditioning heat exchanger, so that an environment where the refrigerant naturally circulates can be realized more quickly. There are advantages you can do. In this case, since the cooling function can be exhibited by opening the expansion valve at an appropriate opening degree, the start-up property of the cooling system can be improved. On the other hand, if the structure of Claim 6 is employ | adopted, since the cooling work of the liquid which has passed through the relief valve can be made to perform the work of cooling, also in this case, the start-up of cooling can be accelerated.

  In the present invention, a fan coil type heat exchanger can be used as the air conditioner heat exchanger. However, if a radiant panel is used as in claim 7, the power of the fan becomes unnecessary, so the power for transporting the refrigerant is eliminated and the cost is reduced. It matches the concept of a natural circulation type cooling system that eliminates suppression and noise. That is, it can be said that the invention of claim 7 is suitable for a natural circulation type cooling device.

It is a typical front view of an embodiment. FIG. 2 is a plan view taken along the line II-II in FIG. 1. (A) (B) is a typical front view which shows an effect | action, (C) is a graph which shows control. It is a figure which shows a modification. It is a figure which shows another modification.

(1). First Embodiment Next, an embodiment of the present invention will be described with reference to the drawings. First, the embodiment shown in FIGS. The natural circulation type cooling device of the present embodiment has a higher position than the group of the air conditioning heat exchanger 2 and the air conditioning heat exchanger 2 (for example, the rooftop), which is composed of a large number of radiation panels 1 arranged on the ceiling surface of the air conditioning space. And a condenser 3 arranged in the above.

  The condenser 3 has a configuration in which a refrigerant heat exchange unit 5 made of a thin tube group is arranged inside (upper part) of the condensation tank 4, and the refrigerant gas returns from the outlet of the air conditioning heat exchanger 2 and the inlet of the condensation tank 4. The refrigerant 6 is connected by a pipe 6, and the inlet of the heat exchanger 2 for air conditioning and the outlet of the condensation tank 4 are connected by a refrigerant liquid feed pipe 7. A cooling pipe 8 is connected to the refrigerant heat exchange unit 5 of the condenser 3, and a cooling water control valve 9 is provided in the cooling pipe 8. Since the air-conditioning heat exchanger 2 and the condenser 3 have different heights, the refrigerant gas return pipe 6 and the refrigerant liquid feed pipe 7 have long portions in the vertical direction (gravity direction).

  As described above, the heat exchanger 2 for air conditioning is composed of a large number of radiating panels 1, and as shown in FIG. 2, the radiating panels 1 are arranged vertically and horizontally. Each radiating panel 1 has a structure in which refrigerant pipes 11 are arranged in a zigzag manner (or integrated) on the upper surface of a rectangular substrate 10 in plan view, and a plurality of radiating panels 1 are arranged in series in the longitudinal direction. Arrangement constitutes one panel unit 12, and the refrigerant pipes 11 of the radiating panels 1 adjacent to each other in the panel unit 12 are connected by a joint (not shown). A number of panel units 12 are arranged in parallel.

  The horizontal lower end of the refrigerant gas return pipe 6 is a collecting pipe 6a having a horizontal posture that is long in the arrangement direction of the panel units 12, and the outlet of the refrigerant pipe 11 in the panel unit 12 is connected to the collecting pipe 6a. 6b is connected.

  On the other hand, the lower end of the refrigerant liquid feed pipe 7 is a horizontal lower part 7a. A long distribution pipe 7b is branched from the horizontal lower part 7a in the direction in which the panel units 12 are arranged. 12, the inlet of the refrigerant pipe 11 is connected via the branch pipe 7c.

  An electromagnetic expansion valve 13 is interposed in the horizontal lower portion 7 a of the refrigerant liquid feed pipe 7, and a horizontal bypass passage 14 is provided between the upstream side and the downstream side across the expansion valve 13. An electromagnetic relief valve 15 is provided in the middle of the bypass passage 14. The relief valve 15 of the present embodiment uses a type that allows gas and liquid to pass through. A pressure sensor 16 is provided in a portion of the horizontal lower portion 7 a of the refrigerant liquid feed pipe 7 on the upstream side of the expansion valve 13 and on the downstream side of the start end of the bypass passage 14.

  The cooling device includes a control device (controller) 17 including a microcomputer, a storage device, and the like, and the valves 9, 13, 15 and the pressure sensor 16 are electrically connected to the control device 17. An operation panel (or remote controller) 18 is also connected to the control device 17 (the control device 17 can be incorporated in the operation panel 18).

(2). Summary Whether the refrigerant (for example, chlorofluorocarbon) exhibits a gas phase or a liquid phase is related to temperature and pressure, and when the operation of the cooling device is stopped for a long time, FIG. As shown in A), the temperature is the same as the outside air temperature, but the pressure is higher than the operating state, so that the refrigerant is in the liquid phase inside the refrigerant liquid feed line 7 and the inside of the condensing tank 4 Then, the liquid phase and the gas phase are separated and balanced.

  When the operation switch of the cooling device is turned on to start the device from this state, the cooling water control valve 9 is opened and the cold water flows to the refrigerant heat exchange unit 5, so that the temperature inside the condensing tank 4 decreases. Then, as shown in FIG. 3B, the liquid level of the condensing tank 4 rises due to the liquefaction of the gas-phase refrigerant in the condensing tank 4, and then the pressure drops in the refrigerant liquid feed line 7. Therefore, a part of the refrigerant is gasified at the lower part (or lower half part) of the refrigerant liquid feed pipe 7. That is, in the lower part of the refrigerant liquid feed line 7, a gas-liquid mixed state in which the liquid phase and the gas phase are mixed is obtained.

  When the expansion valve 13 is opened in this state, the refrigerant is in a gas-liquid mixed state in the lower part of the refrigerant liquid feed line 7 and the pressure is low, so there is not much pressure difference between both sides of the expansion valve 13. On the other hand, since the expansion valve 13 is a needle type and requires a certain pressure difference for the liquid refrigerant to pass, the refrigerant will not be cooled without passing through the expansion valve 13 and the state will continue for a long time. May cause discomfort.

  In contrast, in this embodiment, as shown in FIG. 3B, when the pressure sensor 16 detects that the pressure immediately upstream of the expansion valve 13 is equal to or lower than a predetermined value, the relief valve 15 is opened, The lower part of the refrigerant liquid feed line 7 is connected to the upstream side and the downstream side with the expansion valve 13 interposed therebetween. Then, the gas generated in the refrigerant liquid feed line 7 flows directly to the refrigerant pipe 11 of each radiation panel 1 together with the liquid refrigerant, passes through the radiation panel 1 and flows to the refrigerant gas return line 6. In this case, the expansion valve 13 is fully closed or throttled to a very small opening.

  The refrigerant gas that has passed through the radiation panel 1 reaches the condenser 3 from the refrigerant gas return pipe 6 and is liquefied by being cooled by the condenser 3. For this reason, the liquefaction ratio of the refrigerant progresses with time in the refrigerant liquid feed line 7, and eventually the refrigerant liquid feed line 7 is filled with only the liquid refrigerant, and accordingly, the lower part of the refrigerant liquid feed line 7. The pressure of will also rise.

  In FIG. 3 (C), the change in pressure in the lower part of the refrigerant liquid feed line 7 is displayed, and the pressure decreases from t1 after a slight time lag from the start (t0), and increases when it decreases to the lower limit. After that, when it rises to P2, it will be in a stable steady state. When the pressure drops to a preset value P1, the relief valve 15 is opened, and when the pressure exceeds the set value P1, the relief valve 15 is closed.

  Accordingly, the range from t1 to t3 where the pressure is equal to or less than P1 is the opening region of the relief valve 15. However, since the gas can be quickly removed using the dedicated bypass passage 14, the refrigerant liquid feed line 7 It is possible to shorten the time t4 until the steady state in which the natural circulation is smoothly performed by being filled with the liquid refrigerant.

  An ON / OFF type relief valve 15 may be used to keep it open at a certain opening, or a valve that can adjust the opening is used, and the opening is adjusted according to the pressure. May be. That is, it is possible to control such that the opening degree is increased when the pressure is low and the opening degree is decreased when the pressure is high. It is also possible to make the pressure at which the relief valve 15 opens differ from the pressure at which the relief valve 15 closes.

  The operation of the relief valve 15 does not necessarily need to be based on the absolute value of the pressure sensor 16. For example, another pressure sensor is provided at the start end of the refrigerant gas return pipe 6, and the refrigerant liquid feed pipe 7 and the refrigerant It is also possible to open the relief valve 15 when the pressure difference with the gas return line 6 is lower than a predetermined value.

  Furthermore, as the relief valve 15, it is also possible to let only gas pass through the bypass passage 14 to the radiating panel 1 using a drain trap type (gas-liquid separation passing type) valve. In this case, it is preferable that the expansion valve 13 is appropriately opened to allow the liquid refrigerant to flow through the radiation panel 1 so that the cooling is started together with the start-up. When the pressure of the refrigerant liquid feed line 7 is very low, the expansion valve 13 can be fully opened to support gas discharge.

  In FIG. 1, the bypass passage 14 is shown in a state of protruding upward from the horizontal lower portion 7 a of the refrigerant liquid feed pipe 7. 2, the bypass passage 14 is arranged in a horizontal posture. For this reason, after the relief valve 15 is closed, the gas is not sucked toward the radiation panel 1 and the gas does not remain in the bypass passage 14.

(3). Modification / Others In the modification shown in FIG. 4, the pressure sensor 16 is provided in a portion of the bypass passage 14 on the downstream side of the relief valve 15. In the drawing, the bypass passage 14 is depicted as projecting upward, but is actually in a horizontal position.

  In the modification shown in FIG. 5, an expansion valve 13 and a bypass passage 14 are provided for each panel unit 12. In this example, there is an advantage that each panel unit 12 can be finely controlled. The density of the bypass passage 14 and the relief valve 15 can be arbitrarily set in consideration of the refrigerant piping system, the air-conditioning area, and the like.

  Gas is often generated in the refrigerant liquid feed line 7 at the time of starting, but a single condenser 3 drives a plurality of air conditioning heat exchangers 2 and turns off some of them. Even if the capacity of the condenser 3 with respect to the remaining heat exchanger 2 for air conditioning becomes excessive, the remaining refrigerant liquid feed line 7 may be in a supercooled state and gas may be generated. The gas can be eliminated by opening the relief valve 15 based on the signal from the pressure sensor 16.

  As the condenser, a system in which cooling water is sprinkled through a thin tube through which the refrigerant passes can also be adopted. If conditions such as cost and space permit, as shown by a one-dot chain line in FIG. 4, a portion 14 a on the downstream side of the relief valve 15 in the bypass passage 14 is provided upward, and the gas is supplied to the refrigerant gas return pipe 6. It is also possible to return to the condensation tank 4.

  The present invention can actually be embodied in a natural circulation cooling device. Therefore, it can be used industrially.

DESCRIPTION OF SYMBOLS 1 Radiation panel 2 Heat exchanger for air conditioning 3 Condenser 4 Condensing tank 5 Refrigerant heat exchange unit 6 Refrigerant gas return line 7 Refrigerant liquid feed line 10 Substrate 11 Refrigerant pipe 12 Panel unit 13 Expansion valve 14 Bypass path 15 Relief valve 16 Pressure sensor as an example of pressure detection means 17 Control device (controller)

Claims (7)

A heat exchanger for air conditioning that evaporates and cools in the process of passing the refrigerant, and a condenser that is disposed at a higher position than the heat exchanger, and an outlet of the heat exchanger and an inlet of the condenser Is connected by a refrigerant gas return line, and the inlet of the air conditioner heat exchanger and the outlet of the condenser are connected by a refrigerant liquid feed line, and the heat for air conditioning in the liquefied refrigerant feed line is connected. It is the structure which has provided the expansion valve in the site near the exchanger,
A bypass passage for letting the gas generated in the refrigerant liquid feed pipe escape to the downstream side of the expansion valve 13 is connected to a lower end portion of the refrigerant liquid feed pipe and an upstream side of the expansion valve. A relief valve that opens when the pressure in the vicinity of the upstream side of the expansion valve drops below a preset pressure is provided,
Natural circulation cooling system. The bypass passage is connected to both sides sandwiching the expansion valve in the lower end portion of the refrigerant liquid feed line,
The natural circulation type cooling device according to claim 1. In the lower part of the refrigerant liquid feed line, a pressure detection means is provided on the upstream side of the expansion valve and close to the expansion valve, or on the upstream side of the relief valve in the bypass passage, Opening and closing of the relief valve is controlled based on pressure detection means,
The natural circulation type cooling device according to claim 1 or 2. The bypass passage is disposed in a substantially horizontal posture;
The natural circulation type cooling device according to any one of claims 1 to 4. The relief valve is of a drain trap type that allows gas to pass but does not allow or hardly pass liquid.
The natural circulation type cooling device according to any one of claims 1 to 4. The relief valve is of a type that allows gas and liquid to pass through, and when the relief valve is open, the expansion valve is fully closed or throttled more than in a normal operation state.
The natural circulation type cooling device according to any one of claims 1 to 4. The heat exchanger for air conditioning consists of a radiant cooling panel in which a refrigerant channel is provided on a heat conductive substrate,
The natural circulation type cooling device according to any one of claims 1 to 6.

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