Refrigerated dryers for treating compressed air

Abstract

Refrigerated dryer (100) for treating compressed air, wherein the refrigerated dryer (100) has the following features: a compression refrigeration machine (110) comprising an evaporator (112) with a compressed air refrigerant heat exchanger, a compressor (114), a condenser (116) and an expansion device (118) connected to a refrigerant circuit for conveying flammable refrigerant; a fan unit (120) with at least one fan (122; 224) configured to provide a cooling airflow (X) for the compression refrigeration machine (110); and a housing (130) with a base wall (131) which, in the operational state of the refrigerated dryer (100), faces the floor of an operating environment of the refrigerated dryer (100), a ceiling wall (133) arranged away from the base wall (131), and side walls (135) connecting the base wall (131) and the ceiling wall (133), wherein an air inlet opening (132) for an entry of the cooling air flow (X) into the housing (130) is formed in a lower half of the housing (130) having the base wall (131) or in a side wall (135) of the housing (130), wherein an exhaust air inlet opening (134) for an exit of the cooling air flow (X) from the housing (130) is formed in an upper half of the housing (130) having the ceiling wall (133), wherein the compression refrigeration machine (110) is housed in the casing (130), wherein the casing (130) is shaped to direct the cooling air flow (X) from the supply air opening (132) at least through the condenser (116) and to the exhaust air opening (134), wherein at least one fan (122; 224) of the fan unit (120) is arranged in the casing (130) with respect to a flow direction of the cooling air flow (X) downstream of the compression refrigeration machine (110).

Description

[0001] The present invention relates to a refrigerated dryer for treating compressed air, to a method for operating such a refrigerated dryer and to a corresponding control device.

[0002] For example, so-called safety refrigerants can be used as refrigerants in compression refrigeration machines. Due to their chemical composition, these are non-flammable and non-toxic. With these refrigerants, leaks typically do not require extensive consideration. Flammable refrigerants are also increasingly being used. However, since compressed air refrigeration dryers are often located in machine rooms together with other equipment such as compressed air compressors, it must be ensured that even in the event of a leak of a flammable refrigerant, an explosion cannot occur. This is conventionally achieved primarily through the natural distribution of the refrigerant in the ambient air. However, minimum distances between refrigeration dryers using flammable refrigerants and external ignition sources must be maintained.Ignition sources can include light switches, sockets, lamps, or other machinery in the room. Since compressed air stations are often confined spaces, such minimum distances are disadvantageous.

[0003] Against this background, the present invention provides an improved refrigerated dryer for treating compressed air, an improved method for operating such a refrigerated dryer, and an improved control unit according to the main claims. Advantageous embodiments are described in the dependent claims and the following description.

[0004] According to certain embodiments, a refrigerated dryer can be provided in which minimum distances to ignition sources can be reduced or eliminated, since, in particular, only an airflow exits the refrigerated dryer at a precisely defined point, designed so that even in the event of a refrigerant leak, no ignitable mixture can be present. This can improve the safety and operational flexibility of the refrigerated dryer.

[0005] A refrigerated dryer for treating compressed air is presented, the refrigerated dryer having the following features: a compression refrigeration machine comprising an evaporator with a compressed air refrigerant heat exchanger, a compressor, a condenser and an expansion device connected to a refrigerant circuit for conveying flammable refrigerant; a fan unit comprising at least one fan designed to provide a cooling airflow for the compression refrigeration machine; and A housing with a base wall which, in the operational state of the refrigerated dryer, faces the floor of an operating environment of the refrigerated dryer, a ceiling wall arranged away from the base wall, and side walls connecting the base wall and the ceiling wall, wherein an air inlet opening for the cooling airflow into the housing is formed in a lower half of the housing comprising the base wall or in a side wall of the housing, and wherein an exhaust air outlet for the cooling airflow out of the housing is formed in an upper half of the housing comprising the ceiling wall. wherein the compression refrigeration machine is housed in the casing, wherein the casing is shaped to direct the cooling airflow from the inlet opening at least through the condenser and to the outlet opening, wherein at least one fan of the fan unit is arranged in the casing with respect to a flow direction of the cooling airflow downstream of the compression refrigeration machine.

[0006] A refrigerated dryer can also be called a compressed air refrigerated dryer. Treating the compressed air can involve both drying and cooling. In a refrigerated dryer, the physical relationship between temperature and water vapor content of the compressed air can be used to dehumidify it, as cooling the compressed air causes the water vapor to condense. A compression refrigeration unit is used to cool the compressed air, which is generally saturated with water vapor.

[0007] In the evaporator, the refrigerant extracts heat from the moist compressed air, evaporates, and is then drawn in and compressed by the refrigerant compressor. At this higher pressure level, the heat from the refrigerant is transferred to the cooling air via the condenser. A flow of cooling air is initiated or created by at least one fan. The compression refrigeration machine may also include an additional heat exchanger. The cooled compressed air can be passed through this heat exchanger after the evaporator and used to pre-cool the incoming warm compressed air. This allows the dried compressed air to be reheated and have a lower relative humidity than the incoming compressed air. A fan can also be called a blower. The at least one fan may be speed-controlled.The fan unit can comprise multiple fans, in particular two fans, several fans arranged in parallel, and / or the like. The at least one fan can be positioned downstream of all refrigerant-carrying components with respect to the flow direction of the cooling air it conveys. At least one fan of the fan unit can be located in the housing between the compression refrigeration unit and the exhaust air outlet. The at least one fan can create a negative pressure in the housing and mix refrigerant from a potential refrigerant leak with the cooling airflow. Optionally, the housing can also be shaped to direct the cooling airflow around the other components of the refrigeration cycle or refrigerant circuit, i.e., the evaporator, the compressor, and the expansion element.The expansion element may, for example, include capillaries, at least one throttle valve, an expansion valve, or the like. The expansion element may also be referred to as an expansion device. The condenser may be located closer to the ceiling wall than the evaporator, the compressor, and the expansion element.

[0008] The goal of preventing an ignitable mixture can be achieved not only by maintaining a specific cooling air mass or volume flow rate, but also by ensuring thorough mixing. For example, there may be a minimum cooling air mass or volume flow rate that, even with ideal mixing and the worst-case leakage mass flow rate, remains below the lower explosive limit (LEL). During operation, the cooling air mass or volume flow rate may be significantly higher, particularly due to insufficient mixing, intentional deviation below the lower explosive limit (e.g., 50% LEL), and aging and / or contamination of the dryer.

[0009] According to one embodiment, at least one fan of the fan unit can be arranged in or at the exhaust air opening. The at least one fan arranged in this way thus draws the cooling airflow from the supply air opening through the housing to the exhaust air opening, where it is located. Such an embodiment offers the advantage that a negative pressure can be reliably generated in the housing and that the at least one fan can be safely arranged downstream of any refrigerant-carrying parts of the refrigerant circuit.

[0010] According to one embodiment, the air inlet can be formed in the base wall. This improves protection against any potentially escaping fluid jet. Additionally or alternatively, the exhaust air inlet can be formed in the ceiling wall. This improves airflow mixing as well as the dilution and removal of any potentially leaked refrigerant. Additionally or alternatively, a main plane of extension of the condenser can be oriented orthogonally or obliquely with respect to a main plane of extension of the ceiling wall. This allows the condenser to be oriented appropriately relative to the direction of gravity, either vertically or at a slight incline.

[0011] The fan unit can also include at least one main fan and at least one auxiliary fan. The auxiliary fan can be tilted relative to the main fan. The main fan can be designed for a predefined, required volume flow of the cooling air stream. This design offers the advantage of increased airflow turbulence, thereby improving mixing with any refrigerant that may have escaped through a leak.

[0012] The fan unit can have one or more fans, which can be arranged, for example, in parallel and / or in series. Multiple fans can also be of different sizes. Optionally, at least one additional fan can be provided to circulate the air inside the housing. If the fan unit has more than one fan, a partial shutdown of at least one main fan can occur when the compressor is not running, with, for example, only the larger or smaller fan running as a safety measure to prevent the accumulation of a highly concentrated refrigerant / air mixture.

[0013] Furthermore, at least one air guide vane can be arranged in the housing. This air guide vane can be designed to at least partially redirect the cooling airflow. The air guide vane can be designed as an air baffle plate. Additionally or alternatively, the air guide vane can have a plurality of openings. These openings can, for example, be punched out. In particular, the air guide vane can be designed as a perforated sheet or grille. Such an embodiment offers the advantage that the mixing of the cooling airflow, even with refrigerant potentially escaping through a leak, can be enhanced.

[0014] Furthermore, the housing can accommodate a first air guide wall and a second air guide wall. The first air guide wall can extend between the compression chiller and the supply air inlet along the side walls from the base wall to the ceiling wall. A first opening for the cooling airflow can be formed in the first air guide wall. The second air guide wall can extend between the evaporator, compressor, and expansion element on one side and the fan unit and exhaust air inlet on the other, from at least one side wall to the ceiling wall. A second opening for the cooling airflow can be formed in the second air guide wall, in which the condenser can be located.Such an embodiment offers the advantage that by repeatedly redirecting the cooling airflow, a reliable turbulence and mixing of the cooling airflow can be achieved to improve the dilution of a theoretical refrigerant leakage.

[0015] In this configuration, a third opening for the cooling airflow can be formed in the second air guide wall between the second penetration opening and the ceiling wall. Additionally or alternatively, at least one further air guide wall can be arranged between the second penetration opening of the second air guide wall and the exhaust air opening. Such an embodiment offers the advantage of further improving the dilution or mixing of any potential leakage.

[0016] Furthermore, straight lines between each component of the compression refrigeration machine and the air inlet of the housing can intersect at least one air baffle orthogonally or obliquely. Such an embodiment offers the advantage that any line of sight from the outside to any refrigerant-carrying component, with the exception of the exhaust air inlet and / or the additional air inlets described below, can be avoided, thus preventing a direct leakage path.

[0017] Additionally, at least one further air inlet opening can be formed in at least one of the housing's side walls. Each additional air inlet opening can be located in an area between the compression chiller and the fan unit furthest downstream. The housing thus includes additional openings to mix the cooling airflow, including any potential refrigerant leakage, with ambient air downstream of the compression chiller and, optionally, to further dilute it. Multiple additional air inlets can be provided, which may, for example, be designed as gills. This improves airflow direction. An airflow entering through the additional air inlets essentially perpendicular to the main flow direction of the cooling air can thus further and more effectively mix the cooling airflow.

[0018] Furthermore, the refrigerated dryer can have a mixing chamber which, with respect to the direction of the cooling airflow, is arranged between the compression refrigeration unit and the exhaust air opening in the housing. Such an embodiment offers the advantage that, in the event of a malfunction, any refrigerant escaping through a leak can be distributed as homogeneously as possible in the cooling air.

[0019] Furthermore, the refrigerated dryer can have at least one sensor designed to detect the electrical current draw of the fan unit, the pressure in the housing, and / or the refrigerant pressure in the refrigerant circuit. Such an embodiment offers the advantage that it allows for simple and reliable verification of the functionality of the at least one fan.

[0020] According to one embodiment, the refrigerated dryer can have at least one sensing device configured to acquire measurement data representing the ambient temperature, the evaporation pressure of the refrigerant in the refrigerant circuit, and the condensation pressure of the refrigerant in the refrigerant circuit. Such an embodiment offers the advantage of creating a reliable and meaningful data basis for the safe and demand-based control of the fan unit.

[0021] A method for operating the aforementioned embodiment of a refrigerated dryer is also presented, the method comprising the following steps: Determining the actual volume flow rate of the cooling airflow using the measurement data read in via an interface from at least one detection device; Controlling the fan unit depending on the result of a comparison of the actual volume flow with a target volume flow, in order to set a speed of at least one fan.

[0022] Thus, the method can be implemented to operate an embodiment of the refrigerated dryer comprising at least one detection device. In the control step, a control signal generated by the method can be output to the fan unit via an interface. By executing the operating method, the speed of the at least one fan can be adjusted, for example, to dimension the volume flow rate at all operating points of the refrigerated dryer such that the exiting airflow, particularly from a predefined distance to the air outlet or exhaust opening, does not contain an ignitable mixture with potentially escaped refrigerant, in other words, for example, a maximum of 50 percent of the lower flammability limit (LEL). The volume flow rate can be determined, for example, by CFD analysis (computational fluid dynamics) or experimental design.For this purpose, a leakage rate specified, for example according to standard DIN EN 378-2, of 3 g / s can be used as a basis.

[0023] Advantageously, the target volume flow can be reduced, for example, during idle operation or when the compression refrigeration machine is switched off, if the volume flow required to avoid the ignitable mixture is lower than the volume flow required for cooling during load operation.

[0024] The predefined distance to the air outlet or exhaust opening is defined by an imaginary cuboid enclosing the refrigerated dryer. This imaginary cuboid defines a volume outside of which ignition of a mixture containing potentially leaked refrigerant is impossible. Specifically, outside this cuboid, the mixture is below the lower explosive limit, preferably not exceeding 50% of the lower explosive limit. In a first embodiment, the imaginary cuboid extends beyond the lateral dimensions of the refrigerated dryer by a maximum of 0.8 m on each side, preferably by a maximum of 0.5 m. This dimension advantageously corresponds to a service area that must be kept clear for maintenance work anyway, so that no additional installation space is required. In the vertical direction, the imaginary cuboid extends from the installation surface to a maximum height of 2.5 m.This height is chosen so that it typically ends below ceiling-mounted installations, such as lighting fixtures.

[0025] Alternatively, the dimensions of the imaginary cuboid correspond to the dimensions of the refrigerated dryer, so that the dilution and mixing takes place entirely within the housing of the refrigerated dryer.

[0026] According to one embodiment, the method can include a step for generating a warning message if the actual volume flow rate remains below the target volume flow rate and the rotational speed of at least one fan exceeds a predefined threshold. This allows for reliable warnings should the necessary airflow to ensure sufficient mixing in the event of a leak not be maintained. Optionally, internal information from at least one fan can also be evaluated.

[0027] This process can be implemented, for example, in software or hardware, or in a hybrid form of software and hardware, for example in a control unit.

[0028] The approach presented here further creates a control unit that is configured to perform, control, or implement the steps of a variant of the method presented here in appropriate devices. This embodiment of the invention in the form of a control unit also allows the problem underlying the invention to be solved quickly and efficiently.

[0029] For this purpose, the control unit can have at least one processing unit for processing signals or data, at least one storage unit for storing signals or data, at least one interface to a sensor or actuator for reading sensor signals from the sensor or for outputting control signals to the actuator, and / or at least one communication interface for reading or outputting data embedded in a communication protocol. The processing unit can be, for example, a signal processor, a microcontroller, or the like, while the storage unit can be flash memory, a magnetic storage device, or cloud storage.The communication interface can be configured to read or output data wirelessly and / or via wired connections, whereby a communication interface that can read or output wired data can, for example, read this data electrically or optically from or output it into a corresponding data transmission line.

[0030] In this context, a control unit can be understood as an electrical device that processes sensor signals and outputs control and / or data signals accordingly. The control unit can have an interface, which can be implemented in hardware and / or software. In the case of a hardware-based interface, the interfaces can, for example, be part of a so-called system ASIC, which incorporates various functions of the control unit. However, it is also possible that the interfaces are separate integrated circuits or at least partially comprised of discrete components. In the case of a software-based interface, the interfaces can be software modules, which, for example, are located on a microcontroller alongside other software modules.

[0031] According to one embodiment, the refrigerated dryer can, in addition to the at least one detection device, also include an embodiment of the aforementioned control unit. In this embodiment, the control unit can be connected to the fan unit and the at least one detection device via a signal transmission mechanism. Such an embodiment offers the advantage that the refrigerated dryer can be operated with an optimal cooling airflow at all operating points, and any potentially leaked refrigerant can also be diluted to a safe concentration by the cooling airflow.

[0032] Also advantageous is a computer program product or computer program with program code that can be stored on a machine-readable carrier or storage medium such as a semiconductor memory, a hard disk memory or an optical memory or in cloud storage and is used to carry out, implement and / or control the steps of the method according to one of the embodiments described above, in particular if the program product or program is executed on a computer or device.

[0033] The invention is explained in more detail with reference to the accompanying drawings. These show: Fig. 1A a schematic representation of a refrigerated dryer according to an exemplary embodiment; Fig. 1B a schematic representation of a refrigerated dryer according to an exemplary embodiment; Fig. 2 a schematic representation of a refrigerated dryer according to an exemplary embodiment; Fig. 3 a schematic representation of a refrigerated dryer according to an exemplary embodiment; Fig. 4 a schematic representation of a refrigerated dryer according to an exemplary embodiment; Fig. 5 a schematic representation of a refrigerated dryer with a control unit according to an exemplary embodiment; and Fig. 6 a flowchart of an exemplary embodiment of a method for operating a refrigerated dryer.

[0034] In the following description of preferred embodiments of the present invention, the same or similar reference numerals are used for the elements shown in the various figures and having a similar effect, without repeating these elements.

[0035] Fig. Figure 1A shows a schematic representation of a refrigerated dryer 100 according to an exemplary embodiment. The refrigerated dryer 100, which can also be referred to as a compressed air refrigerated dryer, is used for treating compressed air, in particular for cooling and thereby drying the compressed air. The refrigerated dryer 100 comprises a compression refrigeration unit 110, a fan unit 120, and a housing 130.

[0036] The compression refrigeration machine 110 comprises an evaporator 112 with a compressed air refrigerant heat exchanger, a compressor 114, a condenser 116, and an expansion vessel 118. The evaporator 112, the compressor 114, the condenser 116, and the expansion vessel 118 are connected to form a refrigerant circuit for circulating flammable refrigerant. For this purpose, the evaporator 112, the compressor 114, the condenser 116, and the expansion vessel 118 are connected to each other via pipes.

[0037] The fan unit 120 comprises at least one fan 122. The fan 122 is explosion-proof and does not constitute an ignition source. The fan 122 is designed to generate a cooling airflow X for the compression refrigeration machine 110. The flow path of the cooling airflow X, including flow directions, is illustrated by several arrows. According to the embodiment shown here, the fan unit 120 has only one fan 122. According to other embodiments, the fan unit 120 can have several fans, in particular several fans such as the fan 122, which may be of different dimensions, e.g., different sizes.

[0038] The housing 130 comprises a base wall 131, a top wall 133, and side walls 135. In the operational state of the refrigerated dryer 100, the base wall 131 faces the floor of the operating environment. An air inlet 132 for the cooling airflow X entering the housing 130 and thus the refrigerated dryer 100 is formed in the base wall 131 or in a lower half of the housing 130 that incorporates the same. In other words, the refrigerated dryer 100 rests on the floor of the operating environment with its base wall 131. The machine feet are not shown. The top wall 133 faces away from the base wall 131. An exhaust air inlet 134 for the airflow X exiting the housing 130 and thus the refrigerated dryer 100 is formed in the top wall 133 or in a corresponding upper half of the housing 130. The side walls 135 connect the base wall 131 and the ceiling wall 133.

[0039] The compression refrigeration machine 110 is housed in the casing 130. The casing 130 is thus shaped to accommodate at least the compression refrigeration machine 110. The condenser 116 of the compression refrigeration machine 110 is, for example, located closer to the ceiling wall 133 than the evaporator 112, compressor 114, and expansion element 118 of the compression refrigeration machine 110. A principal plane of extension of the condenser 116 is, for example, orthogonal or oblique to a principal plane of extension of the ceiling wall 133. In this illustration, the principal plane of extension of the condenser 116 is, for example, vertical, while the principal plane of extension of the ceiling wall 133 is, for example, horizontal.The main extension plane of the condenser 116 is, for example, also aligned orthogonally with respect to a main extension plane of the base wall 131, since, according to the embodiment shown here, the main extension planes of the base wall 131 and the ceiling wall 133 run parallel to each other.

[0040] The fan unit 120 is housed in the casing 130. The casing 130 is shaped to direct the airflow X from the supply air opening 132 at least through the condenser 116 and to the exhaust air opening 134. At least one fan 122 or several fans 122 of the fan unit 120, in the embodiment shown here, the fan 122, is arranged in the casing 130 with respect to the flow direction of the cooling airflow X downstream of or relative to the compression refrigeration machine 110.

[0041] The compression refrigeration machine 110 is used to cool compressed air, which is generally saturated with water vapor. In the evaporator 112, the refrigerant extracts heat from the moist compressed air, thereby evaporating and being drawn in and compressed by the refrigerant compressor 114. At this higher pressure level, the heat from the refrigerant is transferred via the condenser 116 to the cooling airflow X. The cooling airflow X is generated by at least one fan 122. The compression refrigeration machine 110 also includes the expansion element 118, such as capillaries, at least one throttle valve, expansion valve, etc. According to one embodiment, the evaporator 112 of the compression refrigeration machine 110 also includes a further heat exchanger, in particular an air-to-air heat exchanger for pre-cooling.The cooled compressed air can be passed through the subsequent heat exchanger after the compressed air-refrigerant heat exchanger and used to pre-cool the incoming warm compressed air. This allows the dried compressed air to be reheated and results in a lower relative humidity than the incoming compressed air.

[0042] According to one embodiment, as also found in Fig. As shown in Figure 1A, the fan 122 is arranged in the exhaust opening 134. Furthermore, according to one embodiment, the housing 130 has at least one air guide vane 136, 138. In other words, according to one embodiment, at least one air guide vane 136, 138 is arranged in the housing 130. The at least one air guide vane 136, 138 is designed to at least partially redirect the cooling airflow X. Additionally or alternatively, at least one through-opening is formed in each of the at least one air guide vane 136, 138; for example, a plurality of through-openings are formed in the at least one air guide vane 136, 138.

[0043] According to the embodiment shown here, the housing 130 has a first air guide wall 136 and a second air guide wall 138. The first air guide wall 136 is arranged between the compression refrigeration unit 110 and the supply air opening 132 and extends along the side walls 135 from the base wall 131 to the top wall 133. A first opening 137 for the cooling air flow X is arranged or formed in the first air guide wall 136. The second air guide wall 138 is arranged between the evaporator 112, the compressor 114, and the expansion element 118 on the one hand, and the fan unit 120 and the exhaust air opening 134 on the other, and extends from at least one side wall 135 to the top wall 133. A second opening for the cooling air flow X is formed in the second air guide wall 138, in which the condenser 116 is arranged. Therefore, the second opening is not explicitly labelled in the illustration.The cooling airflow X runs from the supply air opening 132 through a first air duct formed between the first air guide wall 136 and a side wall 135 in the direction of the ceiling wall 133, then passes through the first passage opening 137, then runs through a second air duct formed between the first air guide wall 136 and the second air guide wall 138 in the direction of the base wall 131, then passes through the second passage opening or the condenser 116 and then runs through a third air duct formed between the second air guide wall 138 and another side wall 135 to the fan 122 in the exhaust air opening 134 of the ceiling wall 133.

[0044] According to one embodiment, all straight lines that can be constructed between each component of the compression refrigeration machine 110 and the supply air opening 132 intersect at least one air guide wall 136, 138 orthogonally or obliquely. Optionally, the same applies accordingly to straight lines between each component of the compression refrigeration machine 110 and the exhaust air opening 134.

[0045] According to one embodiment, a mixing chamber 160, which can also be referred to as a mixing area or mixing region, is also arranged in the housing 130. The mixing chamber 160 represents a part of the interior of the refrigerated dryer 100 for the passage of the cooling air flow X from the compression refrigeration unit 110 to the exhaust air opening 134, wherein potential ignition sources and any refrigerant-carrying components of the compression refrigeration unit 110 are arranged outside the mixing chamber 160. Explosion-proof components, such as the fan 122, are not considered potential ignition sources. An explosion-proof component is understood here to be, in particular, a component that is designed in such a way that it does not generate ignition sparks during operation and whose maximum surface temperature is below the ignition temperature of the refrigerant used, or, in other words, that does not constitute an ignition source.One function of the mixing chamber 160 is, in particular, to distribute any refrigerant escaping through leakage as homogeneously as possible in the cooling air in the event of a fault.

[0046] Fig. Figure 1B shows a schematic representation of a refrigerated dryer 100 according to an exemplary embodiment. The refrigerated dryer 100 corresponds to the refrigerated dryer from Fig. 1A except that in Fig. 1B the main fan or fan 122 is located directly behind or downstream of the condenser 116.

[0047] The space containing components not carrying refrigerant is again explicitly shown here as mixing bracket 160. Here, unlike in Fig. 1A There is no negative pressure in the mixing chamber 160, as the fan 122 pushes air into the mixing chamber 160.

[0048] The fan 122 can also be arranged internally (relative to the housing 130). The fan 122 is designed to create turbulent airflow towards the exhaust opening 134. The fan 122 can also be a radial fan with upward airflow, resulting in additional mixing. The fan 122 can also blow against a baffle plate, further improving the mixing.

[0049] Fig. Figure 2 shows a schematic representation of a refrigerated dryer 100 according to an exemplary embodiment. The refrigerated dryer 100 corresponds to the refrigerated dryer from [reference missing]. Fig. 1A except that in Fig. 2 the fan unit 120 at least one main fan or fan 122, which is supplied to the fan from Fig. 1A corresponds to, and has at least one additional fan 224. The mixing chamber is simply not explicitly shown here.

[0050] The auxiliary fan 224 is tilted relative to the main fan or fan 122. The rotation axis of the main fan is shown only as an example.

[0051] The fan 122 is aligned orthogonally to a principal extension plane of the ceiling wall 133, with one axis of rotation of the auxiliary fan 224 being aligned obliquely or along the principal extension plane of the ceiling wall 133. The auxiliary fan 224 is, for example, and as is shown only by way of example in Fig. As shown in Figure 2, the auxiliary fan 224 is arranged between the condenser 116 and the at least one main fan or fan 122 located in the exhaust opening 134. Thus, the auxiliary fan 224 is arranged and designed to create turbulence in the cooling airflow X between the condenser 116 and the exhaust opening 134.

[0052] Fig. Figure 3 shows a schematic representation of a refrigerated dryer 100 according to an exemplary embodiment. The refrigerated dryer 100 corresponds to the refrigerated dryer from Fig. 1A except that in Fig. 3 the housing 130 has at least one further air guide vane 339, which is arranged in the housing 130 between the second air guide vane 138 and the exhaust opening 134. This is merely an example, and as shown in Fig. As shown in Figure 3, the housing 130 includes two further air guide vanes 339. According to the embodiment shown here, the further air guide vanes 339 form a labyrinth between the condenser 116 and the fan 122 arranged in the exhaust opening 134. The mixing chamber is not explicitly shown here.

[0053] In other words, the housing 130, together with the additional air guide vanes 339, includes additional air baffles that enhance or improve the mixing of the cooling airflow X. The additional air guide vanes 339 can be arranged as desired and optionally have cutouts, thus being designed as perforated sheets, grilles, or the like.

[0054] Fig. Figure 4 shows a schematic representation of a refrigerated dryer 100 according to an exemplary embodiment. The refrigerated dryer 100 corresponds to the refrigerated dryer from Fig. 1A except that in Fig. 4. In at least one of the side walls 135 of the housing 130, at least one further air inlet opening 432 is formed, and in the second air guide wall 138, a third passage opening 440 for the cooling airflow X is formed. The mixing chamber is not explicitly shown here.

[0055] In this embodiment, at least one additional air supply opening 432 is formed or arranged in a region between the compression chiller 110 and the fan 122 of the fan unit 120 located furthest downstream. According to the embodiment shown here, the at least one additional air supply opening 432 is formed in the region between the compression chiller 110 and the fan 122 of the fan unit 120, which is arranged in the exhaust air opening 134. In other words, the at least one additional air supply opening 432 is arranged between the compression chiller 110 and the exhaust air opening 134. The third passage opening 440 is formed or arranged in the second air guide wall 138 between the second passage opening, in which the condenser 116 is arranged, and the ceiling wall 133.

[0056] The housing 130 comprises, with at least one further air inlet opening 432 and / or the third through-opening 440, additional openings which are arranged and shaped to mix and optionally further dilute the cooling airflow X before it exits the housing 130. According to one embodiment, the at least one further air inlet opening 432 and / or the third through-opening 440 comprise gills for improved flow guidance.

[0057] Fig. Figure 5 shows a schematic representation of a refrigerated dryer 100 with a control unit 550 according to an exemplary embodiment. The refrigerated dryer 100 corresponds to or is similar to the refrigerated dryer from one of the figures described above. Examples are shown in Fig. 5 of the refrigeration dryer 100 only the compression refrigeration machine 110, the fan unit 120, the housing 130, at least one detection device 502 and a control unit 550 are shown.

[0058] The at least one acquisition device 502 is designed to acquire and provide measurement data 505. The measurement data 505 represent an ambient temperature, an evaporation pressure of refrigerant in the refrigerant circuit of the compression chiller 110, and a condensation pressure of refrigerant in the refrigerant circuit of the compression chiller 110.

[0059] The control unit 550 is connected to the fan unit 120 and the at least one sensing device 502 via signal transmission. The control unit 550 comprises a detection device 552 and a control device 554. The detection device 552 is configured to determine the actual volume flow rate of the cooling airflow using the measurement data 505 read in from the at least one sensing device 502 via an interface. The control unit 550 is also configured to read the measurement data 505 from the at least one sensing device 502 via the interface. The control device 554 is configured to control the fan unit 120 based on a comparison of the determined actual volume flow rate with a target volume flow rate, for example, by means of a control signal 555, in order to set the speed of the at least one fan.The control unit 550 is also designed to output the control signal 555 to the fan unit 120 via an interface.

[0060] According to one embodiment, the refrigerated dryer 100 comprises at least one sensor 504 in addition to or as an alternative to other sensors. The at least one sensor 504 is designed to detect an electrical current consumption of the fan unit 120, a pressure in the housing 130 and / or a pressure of refrigerant in the refrigerant circuit of the compression refrigeration machine 110.

[0061] Fig. Figure 6 shows a flowchart of an embodiment of method 650 for operating a refrigerated dryer. Method 650 can be implemented to operate the refrigerated dryer from one of the figures described above or a similar refrigerated dryer. Method 650 is implemented using at least one detection device or measurement data 505 and by means of the control unit. Fig. 5 executable. The operating procedure 650 comprises a step 652 of determining and a step 654 of controlling.

[0062] In step 652 of the determination process, the actual volume flow rate of the cooling airflow is determined using measurement data read in via an interface from at least one detection device. Subsequently, in step 654 of the control process, the fan unit is controlled based on the result of a comparison of the actual volume flow rate with a target volume flow rate in order to set a speed of at least one fan.

[0063] According to one embodiment, the operating method 650 also includes a generation step 656. In the generation step 656, a warning message is generated if the actual volume flow rate remains below the target volume flow rate and the rotational speed of the at least one fan exceeds a predefined threshold value or if the fan is a fixed-speed fan.

[0064] With reference to the figures described above, exemplary embodiments and advantages of exemplary embodiments are briefly explained again below in other words and in summary.

[0065] In particular, it is a refrigerated dryer 100 with a flammable refrigerant and a fan unit 120 or a fan system whose airflow is so large at all operating points that the cooling airflow X exiting the housing 130 contains no ignitable mixture from a defined distance from the air outlet of the housing 130. For the purposes of exemplary embodiments, an ignitable mixture is present, in particular, above 50 percent of the lower flammability limit (LEL or LFL). The cooling airflow X or its volume flow is determined, for example, by CFD analysis (Computational Fluid Dynamics) or experimental design. For this purpose, a leakage rate specified, for example, according to standard DIN EN 378-2, of, for example, 3 g / s, is used as a basis. The mixing should work for all possible leakage locations and directions, and thus the speed and / or volume flow of the at least one fan should beVentilators 122 and / or 224 should be sufficiently high.

[0066] Depending on the embodiment, the following features are optionally included: The at least one fan 122 and / or 224 can be speed-controlled. The refrigerated dryer 100 can comprise several parallel fans 122. The refrigerated dryer 100 can include a fan 122 / 224 that operates, particularly when the main fan, which is designed for the required cooling airflow X, is not running and delivers a volume flow necessary for mixing any potential leakage. Sensors are used to check whether the at least one fan 122 and / or 224 is still functional. This can be, for example, measuring the electrical current, a negative pressure in the housing 130, or the pressure in the refrigeration circuit. With regard to the flow direction of the cooling air it delivers, the fan 122 is located downstream of all refrigerant-carrying components, preferably at the outlet of the cooling air from the housing 130.This allows a reliable negative pressure to be generated in the housing 130. The condenser 116 is positioned vertically in the upper part of the housing 130. No gaseous or liquid jet of refrigerant should be able to escape from the refrigerant dryer 100, optionally with the exception of the exhaust vent 134. There should be no line of sight from the outside to any component carrying refrigerant where a probability threshold for leakage is exceeded, optionally with the exception of the exhaust vent 134.

[0067] In particular, a refrigerated dryer 100 is provided, the housing of which has 130 elements that can cause the mixing of a possible refrigerant leak and the cooling airflow X in such a way that no ignitable concentration is present in the exiting cooling airflow X at a predefined distance from the air outlet or exhaust opening 134. Possible such elements include, for example, at least one auxiliary fan 224 with a different flow direction to the main fan 122 within the system, 136, 138, 339 air guide vanes, further supply air openings 432 in the area between the furthest possible leakage point in the flow direction and the fan 122, or the like.

[0068] The predefined distance to the air outlet or exhaust opening 134 is defined by an imaginary cuboid enclosing the refrigeration dryer 100. This enclosing imaginary cuboid defines a volume outside of which ignition of a mixture containing potentially leaked refrigerant is impossible. Specifically, outside this cuboid, the mixture is below the lower explosive limit, preferably not exceeding 50% of the lower explosive limit. In a first embodiment, the imaginary cuboid extends beyond the lateral dimensions of the refrigeration dryer 100 by a maximum of 0.8 m on each side, preferably by a maximum of 0.5 m. This dimension advantageously corresponds to a service area that must be kept clear for maintenance work anyway, so that no additional installation space is required. In the vertical direction, the imaginary cuboid extends from the installation surface to a maximum height of 2.5 m.This height is chosen so that it typically ends below ceiling-mounted installations, such as lighting fixtures. Alternatively, the dimensions of the imaginary cuboid correspond to the dimensions of the refrigerated dryer 100, so that the dilution and mixing take place entirely within the housing 130 of the refrigerated dryer 100.

[0069] In particular, monitoring of the cooling airflow X is provided by measuring ambient temperature, evaporation pressure, and condensation pressure in order to react to changing flow resistances (contamination) within the system. For example, control of a speed-controlled fan 122 and / or 224 is enabled based on the aforementioned measured values ​​and the volume flow calculated from them. A warning or fault message can also be generated if the necessary airflow to ensure sufficient mixing in the event of a leak cannot be maintained. Evaluation of internal information from the fan 122 and / or 224 can also be provided.

[0070] Optionally, the airflow can also be directed around the components of the refrigeration circuit (lower section), i.e., evaporator 112, compressor 114, and expansion element. Small openings created by the design, such as screw connections, sheet metal connections, etc., can also allow air exchange around these components, so that any refrigerant accumulations are carried away from the lower section of the system by the cooling air. The cooling airflow X generated by the at least one fan 122 and / or 224 creates a slight negative pressure in at least a section of the housing or in the entire housing 130. This prevents any refrigerant that might escape from the housing 130 or the refrigerant dryer housing through small gaps and causes it to be expelled through the outlet or exhaust opening 134 located at the top.

[0071] The volume of the mixing chamber 160 is, for example, at least 15%, preferably at least 25%, and particularly preferably at least 30% of the total volume of the housing 130 of the refrigerated dryer. A minimum size of the mixing chamber 160 is necessary for sufficiently thorough mixing. This minimum size can alternatively or additionally be defined by other criteria, such as a minimum value for the average residence time of the cooling air in the mixing chamber 160 or the refrigerant charge.

[0072] Furthermore, the mixing chamber 160 also has a minimum cross-sectional area in a horizontal section plane. In a horizontal section plane at approximately 90% of the total height of the refrigerated dryer 100, the cross-sectional area of ​​the mixing chamber 160 is at least 25%, preferably at least 40%, and particularly preferably at least 50% of the total cross-sectional area of ​​the refrigerated dryer 100.

[0073] The cooling airflow X should also have a certain minimum size to ensure that, after mixing with the largest refrigerant leakage mass flow rate to be considered in the event of a fault, a mixture is formed that is sufficiently far below the LFL (Limited Liability Limit). The largest refrigerant leakage mass flow rate to be considered can be defined as the value to be assumed according to relevant normative requirements or a value determined from a technical perspective or based on tests. An example from EN 378-2, Annex I, paragraphs 5 and 6, is as follows: “For connections and components within the scope of EN 16084, the mass flow rate must not be less than 1 g / s ± 5%. In all other cases, the mass flow rates must not be less than 3 g / s ± 5%. The refrigerant must be released in the vapor phase.”

[0074] Conventionally, the cooling airflow X is designed to match the cooling air requirement of the condenser. Another criterion, according to exemplary embodiments, is the required dilution. If the required dilution results in a larger value for the cooling airflow X than the cooling air requirement of the condenser 116, then, for example, the following applies: The cooling airflow X is dimensioned at least such that, with ideal mixing with the largest refrigerant leakage mass flow rate to be considered, a mixture with a refrigerant concentration below 40%, preferably below 30%, and particularly preferably below 25% of the lower explosive limit is formed in the event of a fault.

[0075] According to one embodiment, another feature of the mixing chamber 160 can be a minimum level of mixing efficiency. The mixing chamber 160 can be designed such that the concentration of refrigerant released in the event of a fault in the cooling airflow X does not exceed 400%, preferably 300%, or particularly preferably 200% of the average concentration that would result from ideal mixing of the released refrigerant with the cooling airflow X at any point in the exhaust air opening 134. Means to achieve this mixing include: - The additional fan 224, whose primary function is not to promote the cooling airflow X, but to mix it, for example by having a conveyance direction perpendicular to or against the flow direction of the cooling air in the mixing chamber 160. - Passive components in the mixing chamber 160 that cause turbulence in the cooling airflow X, e.g. sheet metal strips or sheets with a perforated pattern offset to each other in the direction of flow of the cooling airflow X, such as the further air guide walls 339. - Additional cooling air openings between the mixing chamber 160 and the surroundings of the refrigerated dryer 100, such as the additional air inlet openings 432. Due to negative pressure in the mixing chamber 160 when the fan 122 is located at the outlet opening 134, ambient air is drawn into the mixing chamber 160, causing turbulence in the cooling airflow X.

[0076] The embodiments described and shown in the figures are only examples. Different embodiments can be combined completely or with respect to individual features. An embodiment can also be supplemented by features from another embodiment.

[0077] If an embodiment includes an “and / or” connection between a first feature and a second feature, this can be interpreted as meaning that the embodiment according to one embodiment has both the first feature and the second feature, and according to another embodiment either only the first feature or only the second feature.

Claims

[1] Refrigerated dryer (100) for treating compressed air, wherein the refrigerated dryer (100) has the following features: a compression refrigeration machine (110) comprising an evaporator (112) with a compressed air refrigerant heat exchanger, a compressor (114), a condenser (116) and an expansion device (118) connected to a refrigerant circuit for conveying flammable refrigerant; a fan unit (120) with at least one fan (122; 224) configured to provide a cooling airflow (X) for the compression refrigeration machine (110); and a housing (130) with a base wall (131) which, in the operational state of the refrigerated dryer (100), faces the floor of an operating environment of the refrigerated dryer (100), a ceiling wall (133) arranged away from the base wall (131), and side walls (135) connecting the base wall (131) and the ceiling wall (133), wherein an air inlet opening (132) for an entry of the cooling air flow (X) into the housing (130) is formed in a lower half of the housing (130) having the base wall (131) or in a side wall (135) of the housing (130), wherein an exhaust air inlet opening (134) for an exit of the cooling air flow (X) from the housing (130) is formed in an upper half of the housing (130) having the ceiling wall (133), wherein the compression refrigeration machine (110) is housed in the casing (130), wherein the casing (130) is shaped to direct the cooling air flow (X) from the supply air opening (132) at least through the condenser (116) and to the exhaust air opening (134), wherein at least one fan (122; 224) of the fan unit (120) is arranged in the casing (130) with respect to a flow direction of the cooling air flow (X) downstream of the compression refrigeration machine (110). [2] Refrigerated dryer (100) according to claim 1, wherein at least one fan (122) of the fan unit (120) is arranged in or on the exhaust opening. [3] Refrigerated dryer (100) according to one of the preceding claims, wherein the air inlet (132) is formed in the base wall (131), and / or wherein the exhaust air inlet (134) is formed in the ceiling wall (133), and / or wherein a principal extension plane of the condenser (116) is aligned orthogonally or obliquely with respect to a principal extension plane of the ceiling wall (133). [4] Refrigerated dryer (100) according to one of the preceding claims, wherein the fan unit (120) has at least one main fan (122) and at least one auxiliary fan (224) which is tilted relative to the main fan (122). [5] Refrigerated dryer (100) according to one of the preceding claims, wherein at least one air guide wall (136, 138; 339) is arranged in the housing (130), wherein the at least one air guide wall (136, 138; 339) is designed to at least partially redirect the cooling air flow (X), and / or wherein the at least one air guide wall (136, 138; 339) has a plurality of through-openings. [6] Refrigerated dryer (100) according to one of the preceding claims, wherein a first air guide wall (136) and a second air guide wall (138) are arranged in the housing (130), wherein the first air guide wall (136) extends between the compression refrigeration machine (110) and the supply air opening (132) along the side walls (135) from the base wall (131) to the ceiling wall (133), wherein a first passage opening (137) for the cooling air flow (X) is formed in the first air guide wall (136), wherein the second air guide wall (138) extends between the evaporator (112), the compressor (114) and the expansion element (118) on the one hand and the fan unit (120) and the exhaust air opening (134) on the other hand from at least one side wall (135) to the ceiling wall (133), wherein a second The passage opening for the cooling air flow (X) is formed, with the condenser (116) being arranged in the second passage opening. [7] Refrigerated dryer (100) according to claim 6, wherein a third passage opening (440) for the cooling air flow (X) is formed in the second air guide wall (138) between the second passage opening and the ceiling wall (133), and / or with at least one further air guide wall (339) arranged between the second passage opening of the second air guide wall (138) and the exhaust air opening (134). [8] Refrigerated dryer (100) according to any one of claims 5 to 7, wherein straight lines between each component of the compression refrigeration machine (110) and the air inlet opening (134) of the housing (130) intersect at least one air guide wall (136, 138; 339) orthogonally or obliquely. [9] Refrigerated dryer (100) according to one of the preceding claims, wherein at least one further air inlet opening (432) is formed in at least one of the side walls (135) of the housing (130), wherein each further air inlet opening (432) is formed in an area between the compression refrigeration machine (110) and a fan (122) of the fan unit (120) arranged furthest downstream. [10] Refrigerated dryer (100) according to one of the preceding claims, comprising a mixing chamber (160) which is arranged in the housing (130) with respect to the direction of flow of the cooling air stream (X) between the compression refrigeration machine (110) and the exhaust air opening (134). [11] Refrigerated dryer (100) according to one of the preceding claims, comprising at least one sensor (504) configured to detect an electrical current consumption of the fan unit (120), a pressure in the housing (130) and / or a pressure of refrigerant in the refrigerant circuit. [12] Refrigerated dryer (100) according to one of the preceding claims, comprising at least one detection device (502) configured to detect measurement data (505) representing an ambient temperature, an evaporation pressure of refrigerant in the refrigerant circuit and a condensation pressure of refrigerant in the refrigerant circuit.

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