VENTILATION AND AIR CONDITIONING SYSTEM

Description

[0001] The present invention relates to a ventilation and air conditioning system for a room.

[0002] Modern control and regulation components and systems, especially in nuclear power plants, generate significant heat dissipation through convection and radiation into the technical room in which they are installed. Therefore, cooling such rooms has become increasingly important.

[0003] Typically, this cooling is achieved through an active ventilation and air conditioning system that blows cooled air into the technical room. However, if the active cooling function fails, the systems in the room typically reach the maximum permissible temperature after only about two hours.

[0004] It is known, particularly from WO 2019 / 105559, to provide a passive emergency cooling mode to extend the time (hereinafter referred to as the "grace period") during which the systems present in the room reach the maximum permissible temperature, for example, to up to 24 hours. This is achieved, for example, by providing a passive system with phase-change materials that acts as a heat storage device.

[0005] Patent specification EP 2 686 616 A1 shows a ventilation and air conditioning system with the features of the preamble of claim 1.

[0006] However, such systems are not entirely satisfactory, particularly in terms of robustness and reliability. Indeed, such systems utilize intermediate components, particularly for switching from active to passive cooling mode. These intermediate components can become damaged or lose their functionality over extended periods of standby, reducing the reliability of such systems.

[0007] The present invention aims to provide emergency cooling operation for an active ventilation and air conditioning system in the event of a failure of the active cooling function, particularly due to a power outage. In particular, the current cooling period is to be extended. The system is to operate reliably and be easy to install and maintain.

[0008] For this purpose, the invention proposes a ventilation and air conditioning system having the features of claim 1.

[0009] The basic idea is a passive switchover from active room cooling to passive room cooling with the help of heat storage elements. This passive switchover occurs from forced cooling mode, in which the heat storage elements are cooled within the housing, to natural convection cooling mode, in which the previously cooled heat storage elements provide cooling power for the natural convection airflow. Furthermore, this switchover occurs without the need for additional measures or components, which increases the robustness and thus the reliability of the system.

[0010] Advantageous embodiments are specified in the subclaims and in the description.

[0011] The present invention also relates to a building comprising a space, the space comprising a heat source and a ventilation and air conditioning system as described above.

[0012] The invention is explained by the following description of an embodiment which refers to the attached drawings.

[0013] Preferred embodiments of the invention will now be described in detail with reference to the drawings, in which: Figure 1 shows a plan view of a room containing a number of electrical or electronic control components that generate heat during operation. Figure 2 shows a side sectional view of the room along the Figure 1 indicated section line II-II in which a ventilation and air conditioning system according to the invention is installed and in which an active normal cooling operation is visualized by arrows indicating the air flow. Figure 3 shows the lateral sectional view of Figure 2 , in which a passive emergency cooling operation is visualized. Figure 4 shows a more detailed sectional view of a Figure 2 and Figure 3ventilation and air conditioning system shown.

[0014] Figure 1 shows a plan view of a room 2 containing a heat source 4 and a ventilation and air conditioning system 6.

[0015] Room 2 is specifically a technical room in a nuclear power plant.

[0016] The heat source 4 comprises several electrical and electronic components 8, in particular control and regulation components, which generate heat during operation. The control and regulation components 8 are housed, for example, in cabinets 10, for example, in a central area of ​​the room 2.

[0017] Alternatively, the heat source 4 is of a different type than the electrical / electronic components described so far.

[0018] The ventilation and air conditioning system 6 blows cooled air into room 2 during operation to keep the room temperature below an acceptable maximum value.

[0019] For example, the room temperature should be kept below 25 °C during continuous operation.

[0020] In some embodiments, a heater is also integrated, resulting in a combined heating, ventilation and air conditioning system.

[0021] The ventilation and air conditioning system 6 comprises a cooling air supply system 12, a supply air duct system 14 connected to the cooling air supply system 12 and at least one housing 16 comprising an inlet 18 and an outlet 20.

[0022] The cooling air supply system 12 comprises, for example, an air cooler, which may be a refrigeration machine with a vapor compression cycle or with thermoelectric cooling, and a fan or blower for generating a forced flow of cooled air through the supply air duct system 14.

[0023] For example, the cooling air supply system 12 produces cooled air with a temperature between 15 and 20°C.

[0024] The Figure 1 The cooling air supply system 12, which is only indicated schematically, is arranged outside the room 2, for example.

[0025] During operation of the cooling air supply system 12, a forced flow of cooled air occurs from the cooling air supply system 12 through the supply air duct system 14.

[0026] The supply air duct system 14 is configured to direct the forced flow of cooled air from the cooling air supply system 12 to the inlet 18 of the housing 16 during operation of the cooling air supply system 12.

[0027] In the Figure 1 In the embodiment shown, the ventilation and air conditioning system 6 comprises a plurality of housings 16, which are preferably arranged in parallel.

[0028] As in Figure 1 As shown, the housings 16 are preferably arranged in a row and preferably on a wall 34 of the room 2.

[0029] The housings 16 are arranged, for example, in two parallel rows on two opposite walls 34 of the room 2.

[0030] Alternatively, the housings 16 are arranged in the middle of the space 2 and in particular between the various components 8.

[0031] The supply air duct system 14 includes corresponding branches to each of these housings 16.

[0032] The supply air duct system 14 comprises at least one air duct 22.

[0033] Preferably, the air duct 22 is an air hose made of textile material. A textile material is understood, for example, to be a textile fabric, in particular a textile fabric made of polyester. Such a textile fabric made of polyester offers good resistance to environmental and chemical influences and is easy to wash and clean.

[0034] Alternatively, a metallic air duct 22 can be used.

[0035] The air duct 22 directs the forced flow of cooled air from the cooling air supply system 12 to each of the housings 16.

[0036] For this purpose, the air duct 22 comprises, for example, a branch for each row of housings 16.

[0037] Alternatively, the supply air duct system 14 comprises a plurality of air ducts 22, for example one air duct 22 for each row of housings 16.

[0038] If the air duct 22 is an air hose made of textile material, the air hose 22 preferably has a circular cross-section as shown in the figures. Such a cross-section ensures uniform air distribution. Alternatively, the air hose 22 has a semicircular cross-section.

[0039] The air hose 22, for example, has a diameter of between 300 mm and 800 mm.

[0040] The air hose 22 is preferably permeable over its entire surface. This means that a portion of the forced flow of cooled air can escape at any point along the air hose 22. The supply air duct system 14 preferably includes supporting openings 24 that, during operation of the cooling air supply system 12, direct the forced flow of cooled air from the cooling air supply system 12 to the inlet 18 of a respective housing 16.

[0041] Preferably, at least one opening 24 is arranged opposite the inlet 18 of each housing 16.

[0042] If the air duct 22 is an air hose made of textile material, the openings 24 are preferably formed by nozzles. These nozzles 24 are preferably located on the underside of the air hose 22. Each nozzle 24 directs a stream of cooled air toward the inlet 18 of one of the housings 16. These nozzles can be, for example, full-cone nozzles that direct a cone of cooled air toward the respective inlet 18, or coneless nozzles, or opening nozzles punched into the air hose.

[0043] The nozzles 24 assist the flow by directing the forced flow of cooled air to the inlet 18 of a respective housing 16.

[0044] If the air duct 22 is a metallic air duct, the openings 24 can be formed by nozzles or exhaust grilles. In this case, the openings 24 are preferably the only air outlets from the air duct 22 for the forced flow of cooled air.

[0045] As in the Figure 2 and3 As shown, the supply air duct system 14 is advantageously arranged near a ceiling 26 of the room 2, for example at a distance of at most 20 cm from the ceiling 26.

[0046] For this purpose, the ventilation and air conditioning system 6 comprises a bracket 28 for suspending the supply air duct system 14 from the ceiling 26 of the room 2.

[0047] The support 28 comprises, for example, a cable suspension, preferably as shown in Figure 4 shown, a two-sided cable suspension. Alternatively, the bracket 28 comprises a suspension rail.

[0048] Alternatively, each housing 16 includes a bracket for receiving the supply air duct system 14. In this case, the supply air duct system 14 does not require a separate suspension to the ceiling 26.

[0049] Each housing 16 includes heat storage elements 30 arranged within the housing 16 between the inlet 18 and the outlet 20. Since each housing 16 is substantially identical, only one housing 16 will be referred to below with reference to Figure 4 described.

[0050] The housing 16 preferably consists of a straight, vertically oriented section which directs a downward air flow during cooling operation.

[0051] The housing 16 comprises side walls 32 (facing the room and wall side) which extend vertically between the inlet 18 and the outlet 20.

[0052] In the example shown in the figures, one of the side walls 32 is on the wall 34 of room 2.

[0053] The housing 16 comprises perforated sheet metal panels 36 which form at least one side wall 32 of the housing 16, and in particular form the side wall 32 of the housing 16 which is arranged remote from the wall 34 of the room 2.

[0054] These perforated metal panels 36 define access doors to the housing 16, for example for maintenance work.

[0055] The perforated sheet metal panels 36 are dimensioned with their hole pattern in such a way that the heat storage elements 30 in the housing 16 can also absorb part of the direct heat radiation if the active cooling air flow fails.

[0056] The inlet 18 is located at the upper end of the housing 16, in particular below the supply air duct system 14.

[0057] The supply air duct system 14 is arranged above the inlet 18 at a distance A therefrom, with a gap 38 defined between the supply air duct system 14 and the inlet 18. The distance A is measured along the vertical direction.

[0058] Thanks to this distance A, the inlet 18 of the housing 16 is constantly in flow connection with the space 2, in that air from the space 2 can flow through the gap 38 into the inlet 18 of the housing 16.

[0059] The distance A should be chosen large enough to allow sufficient air to flow from the space 2 between the inlet 18 and the air duct 22, while at the same time being small enough to ensure that little cooled air is lost from the openings 24. The distance A is, for example, between 50 mm and 250 mm.

[0060] Advantageously, as in Figure 4 As shown, the housing 16 includes a baffle 40 disposed at an upper end of the housing 16, which directs air from the space 2 into the inlet 18 of the housing 16. The baffle 40 is configured to direct air from an upper region of the space 2, e.g., warm air, to the gap 38, while simultaneously preventing cooled air from the openings 24 from flowing through the gap 38 into the space 2. This means that the forced flow of cooled air from the openings 24 can flow almost entirely through the inlet 18 into the housing 16.

[0061] Air from room 2, in particular heated air in emergency cooling mode, is guided through the baffle 40 to the inlet 18 and then flows through the housing 16. This provides a simple, reliable emergency cooling of room 2 in the event of a failure of the cooling air supply system 12.

[0062] The outlet 20 leads into the chamber 2 and forms the exit point of the air from the housing 16. The outlet 20 is arranged, as shown in the figures, near a floor 41 of the chamber 2. The outlet 20 comprises, for example, a grille 42.

[0063] The housing 16 comprises a support structure 44 arranged inside the housing 16. The heat storage elements 30 are arranged inside the housing 16 with the aid of the support structure 44 such that, during normal operation, they are subjected to the forced flow of cooled air provided by the cooling air supply system 12.

[0064] Although the heat storage elements 30 create a certain pressure drop, the remaining free space between the heat storage elements 30 and / or between the heat storage elements 30 and the side walls 32 of the housing 16 ensures that the air flow between the inlet 18 and the outlet 20 is not blocked.

[0065] Preferably, the heat storage elements 30 have a plate shape, in particular with flat sides that are aligned parallel to the main flow direction.

[0066] According to one embodiment, a plurality of heat storage elements 30 are arranged parallel and / or one behind the other with respect to the flow direction in the interior of the housing 16.

[0067] The heat storage elements 30 preferably consist of a phase change material (PCM) 46.

[0068] The PCM 46 of the heat storage elements 30 is preferably selected so that it freezes upon contact with the forced flow of cooled air of the cooling air supply system 12, which typically has a temperature in the range of 16°C to 30°C.

[0069] The PCM 46 is also selected to perform a phase change from solid to liquid in the temperature range of 16 °C to 30 °C.

[0070] In other words, the PCM 46 melts preferentially by natural convection with a melting temperature in the range of 16 °C to 30 °C.

[0071] During this freezing / melting process, hysteresis must be taken into account.

[0072] PCM 46 is preferably based on salt hydrates because they are non-flammable or at least flame-resistant. Furthermore, salt hydrates do not exhibit a memory effect, which negatively affects their heat storage capacity during multiple freezing and melting cycles. Salt hydrates also have a high volumetric latent heat storage capacity.

[0073] Alternatively, PCM 46 is based on paraffins.

[0074] The following is a description of the normal cooling operation of the ventilation and air conditioning system 6, ie during the operation of the cooling air supply system 12, with reference to Figure 2 .

[0075] In Figure 2 the air flow through the housing 16 and through the space 2 is shown schematically by corresponding arrows.

[0076] The cooling air supply system 12 generates a forced flow of cooled air. This forced flow of cooled air is then distributed through the supply air duct system 14. The supply air duct system 14, and in particular the supporting openings 24 in the air duct 22, direct the forced flow of cooled air from the cooling air supply to the inlet 18 of the housing or housings 16. The forced flow of cooled air then flows through the housing or housings 16, thus cooling the heat storage elements 30 during normal cooling operation, freezing them, and preparing them for any subsequent emergency cooling operation.

[0077] In normal cooling mode, the heat storage elements 30 are constantly cooled and can therefore store cold.

[0078] For safety reasons, the temperature before and after the heat storage elements 30 is preferably measured in order to derive their heat storage capacity.

[0079] After passing through the heat storage elements 30, the cooled air exits the or each enclosure 16 at the respective outlet 20 and is then distributed to the cabinets 10 by natural airflow in the floor. Due to the higher density of the cooled air, the airflow remains at a low room level, especially near the floor.

[0080] The air in the room is heated by the heat dissipation of components 8 and rises toward the ceiling. The heated air is then discharged from room 2 through an exhaust system 48 under the ceiling 26.

[0081] In normal cooling operation, the heated air is therefore almost exclusively discharged through the exhaust air system 48 of the room 2 and only a negligible amount of heated air enters the or each housing 16 through the respective inlet 18.

[0082] As described above, the ventilation and air conditioning system 6 is configured such that, during operation of the cooling air supply system 12, a forced flow of cooled air occurs from the cooling air supply system 12 through the supply air duct system 14 and then through the housing(s) 16 from the respective inlet 18 to the respective outlet 20, thereby cooling and preferably freezing the heat storage elements 30.

[0083] The following is a description of the emergency cooling operation of the ventilation and air conditioning system 6, ie when the operation of the cooling air supply system fails, with reference to the Figure 3 and 4 .

[0084] If the cooling air supply system 12 fails, for example due to a power failure, the cooling air supply system 12 and the exhaust air system 48 do not generate a forced flow of cooled air, and therefore no cooled air flows from the supply air duct system 14 into the inlet 18 of the housing or housings 16. In this case, the temperatures in the room 2 and between the components 8 can relatively quickly exceed a critical value.

[0085] The passive emergency cooling operation is in Figure 3 shown schematically by arrows indicating the flow direction.

[0086] Heated air with a temperature in the range of, for example, 24°C to 52°C rises to the ceiling and, due to the temperature difference with the cooled interior of the housing or housings 16, enters the or each cooled housing 16 via the respective inlet 18 as a natural convection airflow. The heated air then flows through the housing(s) 16, and in particular through the heat storage elements 30, and cools.

[0087] The switch from forced air flow to natural air flow is therefore carried out without any additional active or passive function.

[0088] During the passive cooling process, the PCM 46 of the heat storage elements 30 is heated by the warm air flow flowing through it, thereby changing its state from solid to liquid (melting). The phase change of the PCM 46 and the associated latent heat allow a relatively large heat storage capacity to be achieved. The heat storage elements 30 thus act as latent heat storage devices and provide cooling power for the natural convection air flow. Thus, the temperature of the PCM 46 is kept approximately constant until it completely melts.

[0089] As in normal cooling operation, the cooled air exits the respective outlet 20 in the bottom area of ​​the or each housing 16 and is distributed by natural air flow to the heat-generating components 8 in order to cool them.

[0090] In this way, a natural convection air flow through the room 2 and through the housing(s) 16 is established and supported as long as the cooling capacity of the heat storage elements 30 is not exceeded.

[0091] As described above, the ventilation and air conditioning system 6 is configured such that when the operation of the cooling air supply system 12 fails, a natural convection air flow occurs through the housing(s) 16 from the respective inlet 18 to the respective outlet 20, the natural convection air flow being cooled by transferring heat to the heat storage elements 30.

[0092] If the cooling air supply system 12 is put back into operation, for example, when the electrical power is switched on again, a forced flow of cooled air through the housing(s) 16 is restored, and the heat storage elements 30 are therefore frozen again. The switch from natural convection air flow to forced air flow also occurs without any additional active or passive function.

[0093] This ventilation and air conditioning system 6 ensures inherently safe cooling of the room for a certain grace period, even in the event of a power failure.

[0094] Overall, thanks to the system according to the invention, a relatively long grace period, for example, of up to 24 hours, is achieved for passive (emergency) cooling after the failure of the cooling air supply system 12. The exact grace period depends in particular on the number of heat storage elements 30, the PCM 46 used, and the geometry of the housing 16.

[0095] The inventors conducted tests and numerical calculations with a system according to the invention, wherein the system comprised a total of twelve housings 16, each housing containing a stack of 180 salt hydrate PCM heat storage elements 30. Each heat storage element 30 had dimensions of approximately 450 x 300 x 15 mm, a weight of approximately 630 kg (including housing and base frame), and a heat capacity of approximately 83,000 kJ. These tests and calculations confirmed that such an exemplary system can provide a total cooling capacity in the range of approximately 1,000 MJ for a room of approximately 72 m² in area and 3.4 m in height with a heating load of approximately 11.5 kW for at least 24 hours.

[0096] In addition, the passive switching from forced air flow to natural air flow without additional devices or measures ensures the robustness and thus the reliability of the ventilation and air conditioning system 6.

Claims

1. - A ventilation and air conditioning system (6) for a room (2), the room (2) containing a heat source (4) and the ventilation and air conditioning system (6), whereby the ventilation and air conditioning system (6) comprises: • a cooling air supply system (12), • comprising at least one enclosure (16): o an inlet (18) located at an upper end of the enclosure (16), o an outlet (20) configured to lead into the room (2), and o Heat storage elements (30) arranged within the enclosure (16) between the inlet (18) and the outlet (20), and • a supply air duct system (14) connected to the cooling air supply system (12); wherein the ventilation and air conditioning system (6) is configured such that: • during operation of the cooling air supply system (12), there is a forced flow of cooled air from the cooling air supply system (12) through the supply air duct system (14) and then through the enclosure (16) from the inlet (18) to the outlet (20), thereby cooling and preferably freezing the heat storage elements (30), and • when the operation of the cooling air supply system (12) fails, a natural convection air flow occurs through the enclosure (16) from the inlet (18) to the outlet (20), the natural convection air flow being cooled by transfer of heat to the heat storage elements (30), characterised in that the supply air duct system (14) is arranged above the inlet (18) at a distance (A) from the latter, a gap (38) being defined between the supply air duct system (14) and the inlet (18), the inlet (18) of the enclosure (16) is adapted to be in constant flow connection with the room (2) by air flowing from the room (2) through the gap (38) into the inlet (18) of the enclosure.

2. Ventilation and air conditioning system according to claim 1, wherein the supply air duct system (14) comprises at least one air duct (22), preferably an air hose made of textile material.

3. Ventilation and air conditioning system according to claim 2, wherein the air duct (22) is an air hose made of textile material and has a circular or semicircular cross-section.

4. A ventilation and air conditioning system according to any one of claims 1 to 3, wherein the supply air duct system (14) comprises supporting openings (24) which, during operation of the cooling air supply system (12), direct the forced flow of cooled air from the cooling air supply system (12) to the inlet (18) of a respective enclosure (16).

5. A ventilation and air conditioning system according to any one of claims 1 to 4, wherein the ventilation and air conditioning system (6) comprises at least one bracket (28) for suspending the supply air duct system (14) from a ceiling (26) of the room (2), or each enclosure (16) comprises a bracket for receiving the supply air duct system (14).

6. A ventilation and air conditioning system according to any one of claims 1 to 5, wherein the enclosure (16) comprises perforated metal panels (36) forming at least one side wall (32) of the enclosure (16).

7. A ventilation and air conditioning system according to any one of claims 1 to 6, wherein the enclosure (16) comprises a baffle (40) arranged at an upper end of the enclosure (16) and adapted to direct the air from the room (2) into the inlet (18) of the enclosure (16).

8. A ventilation and air conditioning system according to any one of claims 1 to 7, wherein the heat storage elements (30) are made of a phase change material (46).

9. The ventilation and air conditioning system of claim 8, wherein the phase change material (46) performs a phase change from solid to liquid in the temperature range of 16 °C to 30 °C.

10. Ventilation and air conditioning system according to claim 8 or 9, wherein the phase change material (46) is based on salt hydrates.

11. A ventilation and air conditioning system according to any one of claims 1 to 10, wherein the heat storage elements (30) have a plate shape.

12. A building comprising a room (2), the room (2) comprising a heat source (4) and a ventilation and air conditioning system (6) according to any one of claims 1 to 11.

13. The building according to claim 12, wherein the outlet (20) is located near a floor (41) of the room (2).

14. A building according to claim 12 or 13, wherein the heat source (4) comprises multiple electrical and electronic components (8).