A cooling installation

Abstract

 A cooling installation comprises a vaporiser for at least partially vaporising a coolant by means of ambient heat, which vaporiser is provided with an inlet for supplying liquid coolant to the vaporiser, which vaporiser has multiple parallel lines (circuits), each of which is provided with an outlet for discharging gaseous and liquid coolant from the vaporiser, each outlet opening directly into a collection vessel for the separation therein of the liquid coolant from the gaseous coolant. Each outlet is provided with separating means for separating the liquid coolant from the gaseous coolant.

Description

[0001] The present invention relates to a cooling installation comprising a vaporiser for at least partially vaporising a coolant by means of ambient heat, which vaporiser is provided with an inlet for supplying liquid coolant to the vaporiser, which vaporiser has multiple parallel lines (circuits), each of which is provided with an outlet for discharging gaseous and liquid coolant from the vaporiser, each outlet opening directly into a collection vessel for the separation therein of the liquid coolant from the gaseous coolant.

[0002] The cooling installation according to the present invention is particularly suitable for use as an air cooler.

[0003] The cooling installation according to the present invention is intended for a coolant circuit. That is to say, a coolant circulates in the cooling installation, the coolant successively being able to vaporise in a vaporiser so as to extract heat from the surroundings, being drawn under suction to a compressor so as to be compressed, then flowing to a condenser to be able to condense and being recycled to the vaporiser again via a float valve in order to able to start a new circuit.

[0004] The coolant that leaves the vaporiser and that is drawn under suction towards the compressor will be predominantly in the gas phase. Some of the coolant can, however, still be in the liquid phase. The coolant that is in the liquid phase cannot be discharged towards the compressor. Therefore, it is known to fit a so-called separator in a cooling installation, which separator separates the coolant that is in the gas phase from the coolant that is still in the liquid phase.

[0005] According to the general state of the art it is customary to connect the outlets of the vaporiser to the separator via a collecting line. This separator usually comprises a relatively large vessel in which the coolant is collected. The fraction that is in the liquid phase will settle in the separator under the influence of gravity. The fraction that is in the gas phase is drawn off at the top of the separator towards the compressor. The separator is also connected to a fluid vessel with the aid of a pressure line. The coolant that has condensed in the condenser is collected in this fluid vessel. With the aid of the pressure line the coolant that is in the liquid phase is transported to the separator so as then to be discharged from the separator, at the bottom of the separator, towards the vaporiser.

[0006] A separator of the type described above demands a relatively large amount of space and is relatively expensive.

[0007] Furthermore, the presence of a separator in a cooling installation according to the type mentioned in the preamble requires the presence of a relatively large amount of coolant in the cooling installation.

[0008] The cooling installation of the type described above can be filled with, for example, NH3. If the cooling installation is used in, for example, the food industry it is a disadvantage that a relatively large amount of NH₃ is present in the cooling installation. After all, in the event of accidents or, for example, in the case of leakage a relatively large amount of NH₃ can escape from the cooling installation and pass into the other installations. NH₃ (ammonia) is a toxic gas that is hazardous for man. Therefore, NH3 must be prevented from being able to come anywhere near foods, both at the point in time when the foods are packed and at the point in time at which the foods have been packed.

[0009] US 5 505 060 discloses a cooling installation for a coolant circuit. A compressor feeds gaseous coolant under pressure to a condenser in which the gas condenses. The liquid coolant formed then flows to a bottom tank that forms an inlet of a vaporiser. The coolant flows through parallel channels in the vaporiser to a top tank. In the top tank the coolant is essentially gaseous, although liquid coolant is still present. This liquid coolant is separated off from the gaseous coolant and flows into an accumulator that is connected to the bottom tank.

[0010] However, separation of the liquid coolant from the gaseous coolant proceeds relatively poorly. As a result liquid droplets can be entrained with the gaseous coolant towards the compressor. The compressor is suitable only for pumping gas. Even the presence of a small amount of droplets can cause damage to the compressor, in particular when ammonia is used as coolant.

[0011] The aim of the present invention is to provide an improved cooling installation.

[0012] This aim is achieved according to the invention in that each outlet is provided with separating means for separating the liquid coolant from the gaseous coolant. Because each outlet has separating means, the liquid coolant will be separated from the gaseous coolant as soon as it flows into the separator, that is to say the collection vessel. The separation is consequently more effective. The outlet thus has both a feed function and a separating function.

[0013] Various embodiments of the separating means are possible. The separating means can, for example, be constituted by saw cuts that have been made in the outlet. An alternative is the use of a demister. A demister is a fine mesh permeable part, for example made of steel wool. Liquid droplets collide with the demister and under the influence of gravity flow downwards over the demister, whilst the gas is allowed through.

[0014] In one embodiment of the invention the collection vessel is directly connected to the outlet of the vaporiser, which vessel is provided with means for discharging the coolant that is in the gas phase from the collection vessel and which collection vessel is connected to the inlet of the vaporiser for feeding the coolant that is in the liquid phase to said inlet by means of gravity.

[0015] What is achieved by this measure is that the coolant that leaves the vaporiser and is still in the liquid phase is immediately fed back to the inlet of the vaporiser. That is to say, a specific separator such as is known in the general state of the art can be omitted from the cooling installation according to the present invention. Firstly, this means that the installation according to the present invention can be of less expensive and more compact construction. Furthermore, there is less coolant in the cooling installation according to the present invention than in the comparable installation according to the state of the art.

[0016] According to the invention it is possible that the connection between the collection vessel and the inlet of the vaporiser comprises an essentially vertically positioned line.

[0017] Coolant that is still in the liquid phase will flow to the inlet of the vaporiser under the influence of gravity. If, as according to the invention, the connection between the collection vessel and the inlet of the vaporiser is positioned essentially vertically, it will be possible for the coolant that is still in the liquid phase to be stored in this vertically positioned line. The quantity of liquid that is in the line can, moreover, be used as an indication of the effectiveness of the cooling installation according to the invention. Depending on the level of the coolant in the connecting line between the collection vessel and the inlet of the vaporiser, more or less coolant can be fed to the inlet of the vaporiser.

[0018] According to the invention it is furthermore possible that the collection vessel comprises a first tube or line, the outlet of the vaporiser opening into said tube or line. In addition, it is possible that the means for discharging the coolant that is in the gas phase comprise a second tube or line that extends into the collection vessel. Furthermore, it is possible that openings are provided in the second tube or line to allow coolant that is in the gas phase to pass through, which openings are made in the top of said second tube or line. The second tube is also used to enable the gas to be withdrawn "directly" under suction, wherein it is prevented that the speed of the gas flow in the collection vessel becomes so high that liquid droplets "are entrained".

[0019] In addition to the measures described above it is furthermore possible that the inlet of the vaporiser is provided with a venturi tube for feeding coolant to the vaporiser via said venturi tube.

[0020] The presence of the venturi tube has the advantage that the primary feed of coolant to the vaporiser takes place through the venturi tube. As a result of the presence of this venturi tube the flow rate of the coolant towards the vaporiser will be higher, so that the effectiveness of the cooling installation can increase, compared with the cooling installation according to the state of the art.

[0021] Reference has always been made above to a cooling installation that is provided with a vaporiser, which vaporiser has one outlet. According to the invention it is furthermore possible that the vaporiser comprises several parallel lines (circuits) each provided with an outlet, each of these outlets connecting directly to the collection vessel. In this embodiment the vaporiser of the cooling installation consists of several parallel lines or circuits in which coolant can vaporise. Each of these lines has an inlet for supplying coolant and an outlet for discharging coolant. These outlets of the various lines each connect to a common collection vessel.

[0022] The invention will be further explained with reference to the appended figures, in which:

Figure 1 shows, diagrammatically, a cooling installation according to the state of the art with a separator therein.

Figure 2 shows the cooling installation according to the present invention.

Figure 3 shows a perspective view of the cooling installation according to Figure 2.

Figure 4 shows a detail of the cooling installation according to Figure 2.

[0023] A cooling installation 1 that makes use of a coolant circuit is shown diagrammatically in Figure 1. The installation 1 comprises a vaporiser 2 in which the coolant is able to vaporise so as to extract heat from the surroundings. The vaporiser 2 has an outlet 3 for discharging the coolant from the vaporiser 2. The outlet 3 is connected via a line 4 to a separator 5. The separator 5 is incorporated in the installation 1 because the coolant that leaves the vaporiser at the outlet 3 will possess both a fraction that is in the gas phase and a fraction that is still in the liquid phase. The fraction that is still in the liquid phase has to be removed from the coolant flow before the coolant can flow from the separator 5 via the line 6 towards a compressor 7. The coolant that is still in the liquid phase will settle in the separator 5 under the influence of gravity and collect at the bottom of the separator. The coolant that is in the gas phase is removed from the separator 5 via the line 6 and transferred to the compressor 7. The compressor 7 is connected to a condenser 9 via a line 8. The coolant can condense in the condenser 9 so as then to be fed in the liquid phase via a line 10 to a fluid vessel 11. The fluid vessel 11 is, in turn, connected to the separator 5 via a pressure line 12. In order to be able to feed coolant to the vaporiser, the bottom of the separator 5 is connected via a line 13 to the inlet 14 of the vaporiser 2.

[0024] It will be clear that a relatively large amount of coolant has to be present both in the separator 5 and in the fluid vessel 11. If the installation according to Figure 1 is used with, for example, NH₃, this installation will be less suitable for applications in the food industry in view of the relatively large amount of NH₃ in the system.

[0025] A cooling installation 20 according to the invention is shown in Figure 2. This cooling installation 20 comprises a vaporiser 21 that is made up of lines 22 situated in parallel. The form of these lines can be seen in particular in Figure 3. Each of the lines 22 is provided with an outlet 23 that opens into a collection vessel 40. The form of the collection vessel 40 can be seen in particular in Figure 3. The coolant that is pumped round in the installation 20 will leave the lines 22 at the outlet 23. On the underside thereof, the outlets 23 are provided with saw cuts 90 for allowing the coolant to pass through, as shown in Figure 4. These saw cuts 90 are made over approximately 60% of the tube diameter. The fraction of the coolant that is in the liquid phase will collect on the bottom of the collection vessel 40. This coolant will flow out via an opening in the base of the collection vessel 40 (see Figure 3) into a line 41 and in doing so flow towards a central inlet 42.

[0026] The saw cuts fulfil a separating function. The two-phase flow of liquid and gaseous coolant will be effectively separated by the saw cuts. Instead of the saw cuts, the outlets 23 can be provided with other separating means, such as a demister (not shown). A combination of these separating means is also possible according to the invention.

[0027] The coolant that has left the lines 22 at the outlets 23 and that is in the gas phase can be removed from the collection vessel 40 via a second tube or line 43. Cut-outs 44 have been made in the top of this tube 43. These cut-outs are, for example, constituted by saw cuts. The second tube 43 is also used to enable the gas to be withdrawn (directly) under suction from the lines 23, the speed in the collection vessel 40 being prevented from becoming so high that liquid droplets are entrained. The coolant that is in the gas phase is transferred via the second tube or line 43 and via a following line 45 to a compressor 27. The compressor 27 is connected via a line 28 to a condenser 29. Condenser 29, in turn, is connected to a fluid vessel 31 with the aid of a line 30. Corresponding to the state of the art, there will be a quantity of coolant that is in the liquid phase in this fluid vessel 31. This coolant is pumped towards the central inlet 42 of the vaporiser 21 via a line 32. It can be seen in Figure 2 that feeding the coolant via the line 32 towards the vaporiser 21 takes place via a so-called ejector or venturi tube 33. A coolant feed valve will be fitted in line 32. This valve is controlled on the basis of the measurement signal from the sensor 50. Because a pressure that is appreciably higher than the pressure in the vaporiser 21 prevails in the fluid vessel 30 it is possible for a valve to suffice for feeding coolant. A coolant pump is thus not needed.

[0028] The presence of the venturi tube has the advantage that the liquid is drawn in from the line 41, so that the sensor 50 can be mounted in a relatively low position. The height of the liquid column in the line 41 and the venturi action together form the driving force for the coolant flow in the air cooler. This driving force is needed to be able to overcome the flow pressure in the cooler. As a result of the use of the venturi there are less stringent requirements in respect of the restriction of the flow pressure drop in the cooler. The mode of operation of the sensor 50 is described below with reference to Figures 2 and 3.

[0029] The central inlet 42 is connected via a tube or line 43 to individual inlets 44 of the various lines 22. The coolant supplied is able to vaporise in the lines 22, heat being able to be extracted from the surroundings. Not all coolant supplied will vaporise. Overall, less than 50% of the coolant mass flow supplied will vaporise. As can also be seen in Figure 3, the construction of the vaporiser 21 is particularly suitable for heat exchange with an air flow. That is to say, the installation 20 according to the present invention can, for example, very suitably be used as an air cooler.

[0030] The installation 20 according to Figure 2 is again shown in Figure 3, but now in perspective. In particular the construction of the collection vessel 40 with the second tube or line 43 therein can be seen in Figure 3. To maintain the clarity of the drawing, only four lines 22 are shown in Figure 3. It is clear that in practice many more lines can be situated between the central feed line 43 and the collection vessel 40.

[0031] A sensor 50 is also shown in Figures 2 and 3. This sensor 50 is fitted in the line 41 that connects the collection vessel 40 to the central inlet 42. The liquid level in the line 41 can be determined with the aid of the sensor 50. This measured value can be used to control the quantity of coolant that is fed via the line 32 from the fluid vessel 31 to the central inlet 42.

Claims

1. Cooling installation comprising a vaporiser (21) for at least partially vaporising a coolant by means of ambient heat, which vaporiser (21) is provided with an inlet (42) for supplying liquid coolant to the vaporiser (21), which vaporiser (21) has multiple parallel lines (circuits) (22), each of which is provided with an outlet (23) for discharging gaseous and liquid coolant from the vaporiser (21), each outlet (23) opening directly into a collection vessel (40) for the separation therein of the liquid coolant from the gaseous coolant, characterised in that each outlet (23) is provided with separating means for separating the liquid coolant from the gaseous coolant.

2. Cooling installation according to Claim 1, wherein the separating means of each outlet (23) are integrated in said outlet (23).

3. Cooling installation according to Claim 1 or 2, wherein each outlet (23) is tubular and the separating means of each outlet each have at least one saw cut (90) that has been made in the peripheral wall of said outlet (23).

4. Cooling installation according to Claim 3, wherein the saw cuts (90) have been made in the underside of the peripheral wall of said outlet (23) that faces the vaporiser.

5. Cooling installation according to Claim 3 or 4, wherein the saw cuts (90) extend over essentially 60% of the tube diameter of said outlet (23).

6. Cooling installation according to one of the preceding claims, wherein the separating means of each outlet each comprise a demister that is connected to the end of the outlet (23).

7. Cooling installation according to Claim 6, wherein the demister comprises a permeable piece made of steel wool.

8. Cooling installation according to one of the preceding claims, wherein the collection vessel (40) is directly connected to the outlet (23) of the vaporiser (21), which vessel (40) is provided with means for discharging the coolant that is in the gas phase from the collection vessel (40) and which collection vessel (40) is connected to the inlet (42) of the vaporiser (21) for feeding the coolant that is in the liquid phase to said inlet (42) by means of gravity.

9. Cooling installation according to Claim 8, wherein the connection between the collection vessel (40) and the inlet (42) of the vaporiser (21) comprises an essentially vertically positioned line (41).

10. Cooling installation according to Claim 9, wherein a sensor (50) is fitted in the line (41) for measuring the liquid level in the line (41).

11. Cooling installation according to Claim 10, wherein a control unit is provided for controlling the amount of coolant to be fed to the inlet (42) on the basis of the value of the liquid level in the line (41) measured by the sensor (50).

12. Cooling installation according to one of the preceding claims, wherein the collection vessel (40) comprises a first tube or line, the outlet (23) of the vaporiser (21) opening into said tube or line.

13. Cooling installation according to one of the preceding claims, wherein the means for discharging the coolant that is in the gas phase comprise a second tube or line (43) that extends into the collection vessel (40).

14. Cooling installation according to Claim 13, wherein openings (44) are provided in the second tube or line (43) to allow coolant that is in the gas phase to pass through, which openings (44) are made in the top of said second tube or line (43).

15. Cooling installation according to one of the preceding claims, wherein the inlet (42) of the vaporiser (21) is provided with a venturi tube (33) for feeding coolant to the vaporiser (21) via said venturi tube (33).

Drawing