High-rigidity structure turbo refrigerator

Abstract

To provide a structure for preventing an evaporator and a condenser from being damaged or deformed by the weight of a compressor in a turbo refrigerator.SOLUTION: At least one first support body 5 having an annular inner peripheral surface is fixed to the outer peripheral surface of the evaporator 3 in a state of being fitted to the outer peripheral surface of the evaporator 3, at least one second support body 6 having an annular inner peripheral surface is fixed to the outer peripheral surface of the condenser 4 in a state of being fitted to the outer peripheral surface of the condenser 4, and the compressor 2 is fixed to the first support body 5 fixed to the evaporator 3 and the second support body 6 fixed to the condenser 4.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a turbo chiller, particularly one that is suitable for use in nuclear facilities and the like as a turbo chiller having a structure that can withstand earthquakes and the like. [Background technology]

[0002] Centrifugal chillers are used in refrigeration and air conditioning equipment and consist of a closed system filled with refrigerant. Centrifugal chillers generally have a refrigeration cycle consisting of a turbo compressor, condenser, expansion device, and evaporator, and produce chilled water by circulating the refrigerant, which is then sent to air conditioners and other equipment using pumps, and are used in air conditioning equipment and process cooling in a variety of industries.

[0003] A compressor is generally a heavy object that contains an electric motor and a compressor in a cast steel casing that is airtightly held in place. A condenser is a device that changes the state of high-temperature, high-pressure gas refrigerant compressed by a compressor into high-temperature, high-pressure liquid refrigerant. Generally, it has a structure in which a heat exchange tube is placed inside a cylindrical thin-walled container, and heat is exchanged between the refrigerant and cooling water through the heat exchange tube. The expansion device is a device that converts high-pressure liquid refrigerant into low-pressure liquid refrigerant using a valve or the like. An evaporator is a device that evaporates the refrigerant by exchanging heat between the refrigerant, which has been reduced in pressure by an expansion device, and the chilled water, thereby lowering the temperature of the chilled water.The evaporator generally has a heat exchange tube inside a cylindrical thin-walled container, and the refrigerant and chilled water exchange heat through the tube. Generally, the condenser and evaporator are arranged with their bases on the same plane, and the compressor is mounted on the evaporator or on the evaporator and condenser.

[0004] For example, in nuclear power facilities and the like, emergency turbo refrigerators are required to be highly robust against earthquakes and the like. In the conventional configuration where the heavy compressor is installed above the evaporator and condenser, the cross-sectional shapes of the evaporator and condenser are circular and made of thin-walled pipes, so the load of the compressor can cause the cross-sectional shapes of the evaporator and condenser to deform into an oval shape or to deform locally.In particular, when an impact such as an earthquake is applied, the predominant frequency of the ground caused by the earthquake and the natural frequency of the refrigerator are close to each other, which can cause resonance and damage to the evaporator and condenser. To address this issue, for example, the strength of the cylindrical tubes of the evaporator and condenser can be improved by increasing the thickness of the tube walls. However, increasing the thickness of the tube walls increases costs, and there are limitations to how thick the tube walls can be, for example, due to manufacturing limitations.

[0005] On the other hand, Patent Document 1 discloses an invention related to a turbo compressor and a refrigerator, in which the compressor is installed on a cylindrical evaporator and condenser via legs or piping. However, no measures are taken to prevent the possibility of damage to the evaporator and condenser, for example, to stabilize the compressor against vibrations. There are also no particular measures taken to prevent breakage or deformation due to resonance caused by earthquake shaking. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-48098 Summary of the Invention [Problem to be solved by the invention]

[0007] The main problem to be solved by the present invention is to provide a structure for preventing or suppressing damage or deformation of the evaporator and condenser due to the weight of the compressor in a turbo chiller in which the compressor is installed above the evaporator and condenser, preferably a turbo chiller with a structure for preventing or suppressing damage or deformation due to resonance phenomena associated with shaking during an earthquake. [Means for solving the problem]

[0008] The means for solving the above problems are as follows.

[0009] (First aspect) an evaporator having a cylindrical tube with its axis oriented horizontally; a condenser arranged in parallel with the evaporator and having a cylindrical tube with its axis directed horizontally; a compressor disposed above the evaporator and the condenser, At least one first support member having an annular inner peripheral surface is fixed to the outer peripheral surface of the evaporator in a state where it is fitted to the outer peripheral surface of the tube of the evaporator, At least one second support member having an annular inner peripheral surface is fixed to the outer peripheral surface of the tube of the condenser in a state where it fits into the outer peripheral surface of the tube of the condenser, the compressor is fixed to the first support member fixed to the evaporator and the second support member fixed to the condenser;

[0010] (Second aspect) an evaporator having a cylindrical tube with its axis oriented horizontally; a condenser arranged in parallel with the evaporator and having a cylindrical tube with its axis directed horizontally; a compressor disposed above the evaporator and the condenser, At least one arc-shaped first support is fixed to the outer peripheral surface of the tube of the evaporator in a state of contact with the outer peripheral surface of the tube of the evaporator so that both lower ends of the arc of the first support are at a height equal to or lower than the height of the axis of the evaporator, At least one arc-shaped second support is fixed to the outer peripheral surface of the tube of the condenser in a state of contact with the outer peripheral surface of the tube of the condenser so that both lower ends of the arc of the second support are at a height equal to or lower than the height of the axis of the condenser, the compressor is fixed to the first support member fixed to the evaporator and the second support member fixed to the condenser; [Effects of the Invention]

[0011] According to the present invention, in a turbo chiller in which the compressor is installed above the evaporator and condenser, damage and deformation of the evaporator and condenser due to the weight of the compressor can be prevented or suppressed, and preferably damage and deformation due to resonance caused by shaking during an earthquake can be prevented or suppressed. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a perspective view of a turbo chiller according to an embodiment of the present invention. [Figure 2] FIG. 2 is a perspective view of an evaporator, a condenser, and a support according to the embodiment. [Figure 3] 1(A) to 1(D) are schematic side views of the support. [Figure 4] FIG. 1 is a schematic diagram of another embodiment in which a support is attached to an evaporator or condenser. [Figure 5] FIG. 1 is a schematic side view of a cross section of an evaporator or condenser and a support in another embodiment. [Figure 6] 1A and 1B are diagrams showing a one-mass system model and a two-mass system model. [Figure 7] FIG. 10 is a schematic explanatory diagram of a model calculation of displacement. DETAILED DESCRIPTION OF THE INVENTION

[0013] Next, an embodiment of the present invention will be described. Note that this embodiment is an example of the present invention, and the scope of the present invention is not limited to this embodiment.

[0014] The present invention relates to a turbo chiller, and more particularly to a structure for supporting a compressor, which is a heavy object, when the compressor is disposed and fixed above an evaporator and a condenser.

[0015] Figure 1 shows an example of a turbo chiller 1 of the present invention. Compressor 2 compresses the refrigerant evaporated by evaporator 3 and sends it to condenser 4, but due to factors such as its relationship with evaporator 3 and condenser 4, the presence of various piping around it, and the need to efficiently utilize the installation area of ​​turbo chiller 1, it is common for the compressor to be placed above evaporator 3 and condenser 4.

[0016] The compressor 2 is an airtight cast steel casing that houses an electric motor and compression device. It draws in the refrigerant gas that has evaporated in the evaporator 3, compresses it, and discharges the high-temperature, high-pressure refrigerant gas into the condenser 4. The condenser 4 has a structure in which a heat exchange tube is placed inside a cylindrical thin-walled container, and the refrigerant, which has been compressed by the compressor 2 and has become high in temperature and pressure, exchanges heat with the cooling water through the heat exchange tube, thereby condensing the refrigerant. The evaporator 3 is a device that has a structure in which a heat exchange tube is placed inside a cylindrical thin-walled container, and evaporates the refrigerant by exchanging heat between the refrigerant that has been reduced in pressure by the expansion device and the cold water, thereby further lowering the temperature of the cold water.

[0017] In conventional turbo chillers, the compressor is typically placed above the evaporator and condenser, and is fixed directly onto the cylindrical evaporator and condenser. In this case, the weight of the compressor acts only on the direct fixing point, resulting in significant deformation due to that weight. If an additional shock is added, such as from an earthquake, resonance may occur, potentially damaging the evaporator and condenser, especially if the dominant frequency of the seismic motion on the chiller's installation floor is close to the chiller's natural frequency.

[0018] (First form) In a first embodiment of the present invention, an annular first support 5 as shown in Fig. 2 is fixed to the outer peripheral surface of the evaporator 3, and an inner annular second support 6 as shown in Fig. 2 is fixed to the outer peripheral surface of the condenser 4, and the compressor 2 is placed and fixed thereon. The shapes of the first support 5 and the second support 6 may be the examples shown in Figs. 3 and 5, which will be described later.

[0019] For example, it is possible to arrange the compressor 2 above the evaporator 3 or the condenser 4 and support it by either the evaporator 3 or the condenser 4. However, since the compressor 2 is a heavy object, it is preferable to distribute the load when supporting it. For this reason, in this embodiment, the compressor 2 is supported by both the evaporator 3 and the condenser 4. For this reason, the evaporator 3 and the condenser 4 are arranged in parallel as shown in FIG. 2.

[0020] A first support 5 and a second support 6 for mounting and fixing the compressor 2 are fixed to the outer peripheral surfaces of the evaporator 3 and the condenser 4 in a state where they fit into the outer peripheral surfaces of the evaporator 3 and the condenser 4. Here, "fixed in a state where they fit" does not necessarily mean that they are fixed in a state where the entire structure is in close contact with each other. The first support 5 and the second support 6 have the same axial core as the evaporator 3 and the condenser 4 . This allows the load received from the compressor 2 to be distributed from the inner surfaces of the first support 5 and the second support 6 to the outer surfaces of the evaporator 3 and the condenser 4, thereby preventing damage and deformation of the evaporator 3 and the condenser 4.

[0021] The effect of fixing the annular first support 5 and second support 6 to the outer peripheral surfaces of the cylindrical evaporator 3 and condenser 4 in a state where they are in contact with each other is considered to be as follows. When a heavy object is placed on top of a cylindrical pipe, the load is locally applied to the pipe. In this case, if the load acts on the pipe via the legs 8 of the compressor, the cross-sectional shape may be deformed into an ellipse.

[0022] Therefore, first, it is necessary to distribute the load from the compressor 2 that the evaporator 3 and the condenser 4 receive so as to avoid localized loads. When the first support 5 and the second support 6, each with an annular inner periphery, are fixed to the outer peripheries of the cylindrical evaporator 3 and the condenser 4 so as to abut against each other, the load from the compressor 2 is transmitted from the inner periphery of the first support 5 and the second support 6 to the outer periphery of the evaporator 3 or the condenser 4. In this way, compared to when the legs 8 of the compressor are directly placed and fixed, the load from the compressor 2 is distributed along the inner periphery of the first support 5 and the second support 6, and the load transmitted from this to the outer periphery of the evaporator 3 and the condenser 4 is distributed.

[0023] Furthermore, when a force is applied from above to a horizontally placed cylindrical structure, a component of force acts that deforms the cylindrical structure in the cross-sectional direction. In this case, if a support having a circular inner periphery is fixed to the outer periphery of the cylindrical structure so that it abuts against the outer periphery, a reaction force acts from the support against the force that tries to deform the cylindrical structure in the cross-sectional direction, thereby exerting the effect of suppressing deformation of the structure in the cross-sectional direction.

[0024] In this way, when the annular first support 5 and second support 6 are fixed to the outer peripheral surfaces of the cylindrical evaporator 3 and condenser 4 so as to abut against each other, the load received from the compressor 2 is dispersed along the inner peripheral surfaces of the first support 5 and second support 6, thereby alleviating the local load. Furthermore, the reaction force from the inner peripheral surfaces of the first support 5 and second support 6 makes it possible to suppress deformation of the cylindrical evaporator 3 and condenser 4 in the cross-sectional direction.

[0025] During an earthquake, resonance can cause problems such as damage to the turbo chiller 1. Resonance is likely to occur when the predominant frequency of the seismic motion of the installation floor where the turbo chiller 1 is installed is close to the natural frequency of the turbo chiller 1. The predominant frequency of the seismic motion of the installation floor is thought to be within the 1 to 33 Hz range, within which seismic motion is believed to have harmful effects, so in order to prevent resonance, it is preferable that the natural frequency of the turbo chiller 1 be higher than this. A high natural frequency means high rigidity and small displacement due to load. For this reason, it is important to increase the rigidity of the turbo chiller 1 from the perspective of preventing damage to the evaporator 3 and condenser 4 due to resonance phenomena during an earthquake. By fixing the annular first support 5 and second support 6 to the outer peripheral surfaces of the cylindrical evaporator 3 and condenser 4 so that they abut against each other, deformation of the evaporator 3 and condenser 4 is suppressed, thereby increasing the rigidity of the turbo chiller 1.

[0026] The first support 5 fixed to the outer peripheral surface of the evaporator 3 and the second support 6 fixed to the outer peripheral surface of the condenser 4 may be provided in one or, more preferably, in plural. When multiple first supports 5 and second supports 6 are provided on the outer peripheral surfaces of the evaporator 3 and the condenser 4, the number of first supports 5 and second supports 6 may be any appropriate number, and can be changed depending on, for example, the size and weight of the compressor 2 and the number of legs of the compressor 2.

[0027] The compressor 2 can have four legs in total, two at the front F and rear B of the evaporator 3 side and two at the front F and rear B of the condenser 4 side, and can be supported by the evaporator 3 and condenser 4 respectively.

[0028] Furthermore, at least four first supports 5,5 are arranged horizontally spaced apart from each other on the evaporator 3, and the front legs 8 and rear legs 8 of the compressor 2 can be fixed to the front support base 7 and rear support base 7, respectively, which are straddled by adjacent first supports 5,5.

[0029] Similarly, at least four second supports 6, 6 are arranged horizontally spaced apart from each other on the condenser 4, and the front leg 8 and the rear leg 8 of the compressor can be fixed to the front support base 7 and the rear support base 7, respectively, which are straddled by adjacent second supports 6, 6.

[0030] In this way, as shown in FIG. 2, four first supports 5 can be arranged adjacent to each other in the evaporator 2, and four second supports 6 can be arranged adjacent to each other in the condenser. The compressor 2 can be disposed above the evaporator 3 and condenser 4 by placing and fixing the legs 8 of the compressor on each of the common support bases 7 that are installed across the tops of adjacent supports. The load of the compressor 2 is distributed over the four support bases 7, and the load received by one support base 7 can be distributed and transmitted to the outer circumferential surfaces of the evaporator 3 and condenser 4 by the first support base 5 and second support base 6 at the bottom. Furthermore, the load received by one support base 7 that supports the legs 8 of the compressor is distributed to the adjacent set of first supports 5 or the set of second supports 6, which not only increases the fixing strength of the compressor 2 compared to when the legs 8 of the compressor are fixed to one support, but also has the advantage of being able to effectively suppress resonance phenomena that occur due to shaking, particularly during earthquakes.

[0031] It is desirable that the bottom surface of the support base 7 straddling the first support 5 at the front F and the first support 5 at the rear B, and the bottom surface 7 of the support base straddling the second support 6 at the front F and the second support 6 at the rear B, have a shape that matches the outer peripheral surface of the first support 5 or the second support 6. In this case, a part of the outer peripheral surface of the first support 5 or the second support 6 can be flattened so that the flat bottom surface of the support base 7 is flush with it.

[0032] The shape of the first support 5 or the second support 6 can be any suitable shape. For example, it can be formed in a circular ring shape as shown in Fig. 3(A), formed with a flat portion 5a (6a) at the top as shown in (B), formed with a rectangular outer shape as shown in (C), or formed with a step portion 5b (6b) in addition to the flat portion 5a (6a) as shown in (D).

[0033] The shape of the first support 5 or the second support 6 can be modified such that instead of being flange-shaped, the first support 5A or the second support 6A is strip-shaped as shown in FIG. 4(A), or the first support 5B or the second support 6B is strip-shaped and wide across the front F and the rear B as shown in FIG. 4(B).

[0034] (Support) Here, the resistance of the support to deformation can be determined by reference to the second moment of area formula. In the case of an outer peripheral, annular support as shown in Figure 3(A), the second moment of area formula is expressed by the following formula 1.

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[0035] According to Equation 1, when the support is a hollow disk as shown in Figure 3(A), the difference between the outer and inner diameters of the hollow disk has a greater effect on the deformability of the support than the thickness of the hollow disk. In other words, increasing the difference between the outer and inner diameters of the hollow disk is important for increasing the strength of the support.

[0036] From the above viewpoint, in order to increase the strength per unit weight of the support, it is more effective to increase the difference between the outer diameter and the inner diameter than to increase the thickness of the support. However, if the thickness of the support is too thin, the weight of the compressor 2 will cause the support to buckle. For this reason, the plate thickness of the support is preferably 10 to 30 mm. More preferably, it is 15 to 25 mm. If it is thinner than this, the support may buckle. Furthermore, if it is thicker than this, it will not be possible to increase the difference between the outer diameter and the inner diameter per unit weight, and sufficient strength will not be ensured. The difference between the outer diameter and the inner diameter is preferably 100 to 300 mm, and more preferably 150 to 250 mm. If the difference between the outer diameter and the inner diameter is small, it is disadvantageous in terms of strength. If the difference between the outer diameter and the inner diameter is too large, the thickness of the support cannot be increased based on the unit weight of the support, which may cause buckling. Furthermore, the compressor 2 is installed at a higher position, which makes it unstable against shaking such as earthquakes. The material of the support is preferably a steel material such as carbon steel or alloy steel.

[0037] It is preferable that the compressor 2 is supported by distributing the load to each of the evaporator 3 and the condenser 4, but it may also be supported by only the evaporator 3 or only the condenser 4. In this case, one or more supports are fixed to only one side supporting the compressor 2, and the compressor 2 is placed on top of them directly or via a support stand 7.

[0038] (Second form) The shape of the support may be annular, or may be arc-shaped as shown in Figures 5(A) and 5(B). Figure 5(A) is an example of an arc with an opening angle of 270 degrees excluding the bottom end, and (B) is an example of an arc with an opening angle of 180 degrees only in the upper half.

[0039] In the case of the arc support, it is desirable from the viewpoint of strength that at least the upper half of the support be covered for 180 degrees. The outer circumferential surface of the arc support can also be formed into various shapes, similar to the case of the annular support.

[0040] (Effect of the presence or absence of a support on natural frequency) The natural frequency of the refrigerator 1 is important when considering earthquakes, etc. If the dominant frequency of the ground caused by an earthquake and the natural frequency of the refrigerator 1 are close to each other, a resonance phenomenon will occur, increasing the possibility of damaging or deforming the refrigerator. The natural frequency of the refrigerator 1 is expressed as follows using the one mass point model of FIG. 6(A).

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[0041] According to Equation 2, the natural frequency of refrigerator 1 increases as the spring constant of refrigerator 1 increases and as the mass of refrigerator 1 decreases. If the mass of refrigerator 1 is constant, the natural frequency can be increased by increasing the spring constant. The spring constant increases as the displacement decreases when a constant force is applied. Therefore, if refrigerator 1 is designed to be less susceptible to displacement when a constant force is applied, the spring constant will increase, and as a result, the natural frequency of refrigerator 1 will increase.

[0042] Here, when focusing on the magnitude of displacement, the bending deformation of the cylindrical tubes of the condenser and evaporator and the local deformation of the compressor legs are larger and more dominant than other deformations (for example, twisting of the tubes, bending of the plates on both sides that support the tubes, deformation due to torsion, etc.), and the spring and mass can be considered as these two parts. In this case, using the two-mass system model in Figure 6(B), the natural frequency of the refrigerator can be expressed as follows:

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[0043] Considering a semi-cylindrical model shown in the skeleton diagram in Figure 7(A) as the evaporator 3 or condenser 4, we performed simulations to determine the displacement of the top when a load is applied to the top without any supports, and the displacement when a load is applied from the top of the supports with two supports as shown in Figure 7(B). Figure 7(B) is a schematic diagram that clearly illustrates the displacement. As a result of the simulation, when the displacement of the upper semi-cylindrical part without supports was set to 1, the displacement with supports was 0.24. This result shows that when supports are provided, rigidity increases, and displacement becomes less likely when the same load is applied. Therefore, it was shown that the spring constant of the refrigerator is larger when supports are provided.

[0044] This indicates that the natural frequency of the refrigerator 1 increases when a support is provided, and considering that the predominant frequency of seismic motion on the installation floor is usually within the range of 1 to 33 Hz, resonance phenomena are less likely to occur during an earthquake.

[0045] To give a specific example, when no support is provided, the natural frequency due to local deformation alone is about 30 Hz, and the natural frequency due to bending deformation of the cylindrical tubes of the condenser and evaporator alone is about 60 Hz. In this case, according to equation (3), the natural frequency of the refrigerator is 26.8 Hz, which is below 33 Hz. On the other hand, as described above, the local displacement when the support is provided is 0.24 times the displacement when no support is provided, which is 1, so the spring constant K1 of the local deformation is (1 / 0.24). From equations (4) and (3), the natural frequency of the refrigerator is approximately 43 Hz, which is a value larger than 33 Hz. Equation (3) shows that when no support is provided, even if the bending deformation is set to 0 (f2 = ∞) by supporting the centers of the condenser and evaporator from the installation floor, the natural frequency of the refrigerator will be 30 Hz due to local deformation alone, which is smaller than 33 Hz. This shows that providing the support of the present invention is very effective.

[0046] In an actual chiller, not only are the local deformation springs and bending springs of the cylindrical tubes of the condenser and evaporator replaced with springs due to torsional deformation of these tubes, but also springs due to bending and torsional deformation of the plates supporting these tubes, all arranged in series and parallel, and the mass must be distributed. Therefore, a separate beam model evaluation was conducted to evaluate the rigidity of the centrifugal chiller 1. The results showed that the natural frequency of the centrifugal chiller 1 was 47 Hz when using a hollow disk-type support. Resonance is likely to occur when the dominant frequency of the seismic motion of the installation floor where the centrifugal chiller 1 is installed is close to the natural frequency of the centrifugal chiller 1. The dominant frequency of the seismic motion of the installation floor is usually within the range of 1 to 33 Hz, and when supports are provided, the value is higher, indicating that the system is less susceptible to resonance caused by earthquakes.

[0047] The present invention is not limited to the contents described in the above embodiment, and various modifications and changes are possible within the scope of the gist of the invention. [Industrial Applicability]

[0048] The present invention relates to a turbo chiller used in air conditioning equipment and process cooling in a variety of industries, and has improved strength, making it particularly suitable for use as a turbo chiller that is less susceptible to damage, etc., during earthquakes. [Explanation of symbols]

[0049] 1...turbo chiller, 2...compressor, 3...evaporator, 4...condenser, 5...first support, 6...second support, 7...support base, 8...compressor leg, F...front, B...rear, O...axis center.

Claims

1. an evaporator having a cylindrical tube with its axis oriented horizontally; a condenser arranged in parallel with the evaporator and having a cylindrical tube with its axis directed horizontally; a compressor disposed above the evaporator and the condenser, At least one first support member having an annular inner peripheral surface is fixed to the outer peripheral surface of the tube of the evaporator in a state where it fits into the outer peripheral surface of the tube of the evaporator, At least one second support member having an annular inner peripheral surface is fixed to the outer peripheral surface of the tube of the condenser in a state where it fits onto the outer peripheral surface of the tube of the condenser, The turbo chiller, wherein the compressor is fixed to the first support member fixed to the evaporator and the second support member fixed to the condenser.

2. the first supports are disposed adjacent to the evaporator at a distance in the horizontal direction, and legs of the compressor are fixed to support bases provided across the first supports; the second supports are disposed adjacent to the condenser at a distance in the horizontal direction, and legs of the compressor are fixed to support bases provided across the second supports; The turbo chiller according to claim 1,

3. At least four of the first supports are arranged at intervals in the horizontal direction of the evaporator, and front legs and rear legs of the compressor are fixed to front support bases and rear support bases respectively provided across adjacent first supports, At least four of the second supports are arranged at intervals in the horizontal direction of the condenser, and front legs and rear legs of the compressor are fixed to front support bases and rear support bases respectively provided across adjacent second supports, The turbo chiller according to claim 1,

4. The turbo chiller according to any one of claims 1 to 3, wherein the first support body and the second support body are annular, have a horizontal thickness of 10 to 30 mm, and have a difference between their outer diameters and inner diameters of 100 to 300 mm.

5. an evaporator having a cylindrical tube with its axis oriented horizontally; a condenser arranged in parallel with the evaporator and having a cylindrical tube with its axis directed horizontally; a compressor disposed above the evaporator and the condenser, At least one arc-shaped first support is fixed to the outer peripheral surface of the tube of the evaporator in a state of contact with the outer peripheral surface of the tube of the evaporator so that both lower ends of the arc of the first support are at a height equal to or lower than the height of the axis of the evaporator, at least one arc-shaped second support is fixed to the outer peripheral surface of the tube of the condenser in a state of contact with the outer peripheral surface of the tube of the condenser such that both lower ends of the arc of the second support are at a height equal to or lower than the height of the axis of the condenser; the compressor is fixed to the first support member fixed to the evaporator and the second support member fixed to the condenser.

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