DESICCANT DEHUMIDIFIER AND METHOD PERFORMED BY A CONTROL DEVICE FOR CONTROLLING A DESICCANT DEHUMIDIFIER - Patent application

Abstract

The present disclosure relates to a method performed by a control device (200) for controlling a desiccant dehumidifier (1), the method including: controlling (s101) a heater device (28) disposed in fluid communication with a regeneration air circuit (12) upstream of a desiccant rotor (2) to provide regeneration air (14) at a substantially constant temperature; and controlling (s102) a volumetric flow rate of the substantially constant temperature regeneration air (14) through a regeneration section (16) of the desiccant rotor (2) based on a predetermined target humidity within the regeneration section (16). The present disclosure further relates to a computer program, a computer-readable medium (202) having the computer program stored thereon, and the desiccant dehumidifier (1).

Description

[Technical Field]

[0001] The present disclosure relates to a method, a computer program, a computer-readable medium, and a desiccant dehumidifier. More particularly, the disclosure relates to a method executed by a control device for controlling a desiccant dehumidifier. The present disclosure also relates to a computer program, a computer-readable medium having the computer program stored thereon, and a desiccant dehumidifier comprising: a desiccant rotor rotatably arranged about a central axis of the desiccant rotor; a process air circuit arranged to deliver process air through a treatment section of the desiccant rotor; a regeneration air circuit arranged to deliver regeneration air through a regeneration section of the desiccant rotor; a fan arranged downstream of the desiccant rotor in the regeneration air circuit and configured to generate a regeneration air flow in the regeneration air circuit; and a heater device arranged upstream of the desiccant rotor in fluid communication with the regeneration air circuit. [Background technology]

[0002] Dehumidifiers, such as adsorption dehumidifiers and condensing dehumidifiers, are used to separate and remove moisture from air. Adsorption dehumidifiers typically include a dehumidifying element in the form of a wheel or rotor that holds a desiccant material that is effective at attracting and retaining water vapor. The desiccant rotor can be divided into two sections: a treatment section and a regeneration section. The air stream to be dehumidified, i.e., process air, passes through the treatment section of the desiccant rotor, and the desiccant material in the rotor extracts moisture from the process air so that the process air can exit the rotor as dry air. Simultaneously, the desiccant material is regenerated by another air stream, i.e., the regeneration air stream. The regeneration air stream flows through the regeneration section while the desiccant rotor slowly rotates about its longitudinal axis. Simultaneous dehumidification of the process air and regeneration of the desiccant material allow the dehumidifier to operate continuously.

[0003] US2007056307 discloses an example of a dehumidifier having a desiccant wheel.

[0004] The air flowing through the regenerator is heated by a heater device. The heat from the heater device can be generated by electricity. The airflow through the regenerator can be generated by an electrically driven fan. The heated air flowing through the regenerator releases moisture from the desiccant rotor, thereby drying the rotor. Summary of the Invention

[0005] The release of moisture from the desiccant rotor by the regeneration air reduces the humidity within the rotor, allowing the desiccant rotor to extract moisture from the process air passing through the treatment section. However, heating the regeneration air to dry the desiccant rotor is energy-intensive and costly. There are known desiccant dehumidifiers that use unlimited power to quickly reach steady state, but with little concern about energy use.

[0006] Furthermore, known heater devices for heating regeneration air may not deliver regeneration air with a uniform temperature distribution within the desiccant rotor, making it difficult to control the desiccant dehumidifier and potentially resulting in excessive heating of the desiccant rotor, which may result in the desiccant rotor becoming unnecessarily dry.

[0007] In some cases, it may be beneficial to operate a desiccant dehumidifier in different modes depending on the air conditions and needs within the space or room being treated. In some situations, low cost for drying a room is a priority. In other situations, the same desiccant dehumidifier must be used to reduce humidity in the same room in a short period of time. In still other situations, it may be important to avoid condensation of fluids on the walls and surfaces of the room.

[0008] Therefore, what is needed is an improved desiccant dehumidifier and method for controlling the desiccant dehumidifier that reduces the energy requirements for treating the air in a space or room in one mode of operation, quickly reduces the humidity in the same space or room in another mode of operation, and prevents condensation on the walls and surfaces of the space or room in yet another mode of operation.

[0009] It is an object of the present disclosure to mitigate, alleviate or eliminate one or more of the above-identified deficiencies and drawbacks of the prior art, or at least to solve the above-identified problems.

[0010] Another object of the present invention is to achieve a desiccant dehumidifier and a method for controlling the same that reduces the energy requirements for treating the air in a space or room in one mode of operation, thus reducing the cost of heating the regeneration air.

[0011] It is yet another object of the present invention to achieve a desiccant dehumidifier and a method for controlling the desiccant dehumidifier that reduces humidity in the same space or room in a short period of time in one operating mode.

[0012] It is yet another object of the present invention to provide a desiccant dehumidifier and method for controlling the desiccant dehumidifier that prevents condensation on the walls and surfaces of a space or room in one mode of operation.

[0013] These objects are achieved by the initially defined method, which further includes controlling the heater device to provide regeneration air at a substantially constant temperature, and controlling a volumetric flow rate of the substantially constant temperature regeneration air through the regeneration section based on a predetermined target humidity within the regeneration section of the desiccant rotor.

[0014] A desiccant dehumidifier is configured to process air to separate and remove moisture, such as water vapor, from the air. Dry air can be delivered from the desiccant dehumidifier to a space or room where humidity control is required. The desiccant rotor contains a desiccant material that is effective at attracting and retaining water vapor. A process air stream flows through the process air circuit and passes through the desiccant rotor. The desiccant material in the main desiccant rotor extracts moisture from the process air in the process air stream, allowing the process air to exit the desiccant rotor as dry air. The moisture extracted from the process air is removed from the desiccant material in the desiccant rotor by a regeneration air stream flowing through the desiccant rotor in the regeneration air circuit. The moisture removed from the desiccant material is transported downstream from the desiccant rotor by the regeneration air stream in the regeneration air circuit. A fan located downstream of the desiccant rotor is configured to generate a regeneration air stream in the regeneration air circuit.

[0015] The heater device is configured to increase the temperature of the regeneration air in the regeneration air circuit. The heater device can generate regeneration air at a constant or substantially constant temperature. Furthermore, the heater device can generate a regeneration air temperature that is uniformly or substantially uniformly distributed in the regeneration section. The substantially constant temperature regeneration air provided by the heater device can be selected based on a selected predetermined target humidity. Furthermore, the regeneration air flow is controlled by the regeneration air fan to achieve a target moisture outlet content. The heater device has a flattening effect on the temperature distribution, thereby making it uniform. To optimize the energy usage of the unit, it is beneficial not to over-dry the desiccant rotor in the regeneration section. This is because excessive dehumidification requires excessive heat energy, which is costly. To avoid excessive drying, and if the regeneration air flow in the desiccant dehumidifier fluctuates, the control device can limit the regeneration air flow to a pre-calculated value to ensure low energy usage. This allows for smoother and slower regeneration air flow fluctuations when reaching the target humidity is not time-critical, but saves costs. In this manner, the heater device can be controlled in the first operating mode to smoothly reach the target humidity with reduced overall energy usage. Therefore, controlling the humidity in a space or room using a variable regeneration air flow limited by a preset value can minimize the overall energy usage to reach the target room humidity. This method for controlling a desiccant dehumidifier in the first operating mode can reduce the energy requirements for treating the air in the space or room, thereby reducing the cost of heating the regeneration air. Furthermore, the desiccant dehumidifier can be switched to a second operating mode to reduce the humidity in the same space or room in a shorter period of time. The heater device can be controlled to provide a substantially constant, high-temperature regeneration air, and the volumetric flow rate of the substantially constant, high-temperature regeneration air through the regeneration section can be controlled based on the predetermined, low target humidity of the desiccant rotor.Selecting this second operating mode may increase the energy demands on both the heater device and the fan located in the regeneration circuit, but may allow the target temperature to be reached in a shorter time.

[0016] The desiccant dehumidifier may further include a first humidity sensor disposed in the process air circuit downstream of the desiccant rotor. Controlling the volumetric flow rate of the regeneration air through the regeneration section is further based on the current humidity in the desiccant rotor determined by the first humidity sensor. The first humidity sensor disposed in the process air circuit may be disposed near the desiccant rotor or at a limited distance from the desiccant rotor. The first humidity sensor is configured to transmit a signal to a control device regarding the humidity sensed in the process air circuit downstream of the rotor. In some operating modes of the desiccant dehumidifier, the humidity in the process air circuit downstream of the desiccant rotor may be within a range of 0% to 10% RH, preferably within a range of 0% to 5% RH, and most preferably within a range of 0% to 2% RH. The humidity in the process air circuit downstream of the desiccant rotor indicates the humidity in the regeneration section of the desiccant rotor. In this manner, the humidity in the regeneration section of the desiccant rotor can be controlled.

[0017] The desiccant dehumidifier may further include a second humidity sensor disposed downstream of the desiccant rotor in the regeneration air circuit. Controlling the volumetric flow rate of the regeneration air through the regeneration section is further based on the current humidity in the desiccant rotor determined by the second humidity sensor. The second humidity sensor disposed in the regeneration air circuit may be disposed near the desiccant rotor or at a limited distance from the desiccant rotor. The second humidity sensor is configured to transmit a signal related to the humidity sensed in the regeneration air circuit downstream of the rotor to a control device. The humidity in the regeneration air circuit downstream of the desiccant rotor may indicate the humidity in the regeneration section of the desiccant rotor. In some operating modes of the desiccant dehumidifier, the humidity in the regeneration air circuit downstream of the desiccant rotor may be within a range of 50% to 100% RH, preferably within a range of 65% to 95% RH, and most preferably within a range of 70% to 90% RH. In this manner, the humidity in the regeneration section of the desiccant rotor may be controlled. In the desiccant dehumidifier, a second humidity sensor can be placed in combination with the first humidity sensor. In the desiccant dehumidifier, values ​​from the second humidity sensor can be analyzed in combination with values ​​from the first humidity sensor.

[0018] The desiccant dehumidifier may further include a third humidity sensor disposed within the space fluidly connected to the process air circuit. The step of controlling the volumetric flow rate of the regeneration air through the regeneration section may further be based on a target operating time of the desiccant dehumidifier for reaching a target humidity level within the space determined by the third humidity sensor. The third humidity sensor may be disposed within the space to be dried by the desiccant dehumidifier. The third humidity sensor may be configured to send a signal regarding the humidity detected within the space to the control device. The desiccant dehumidifier may be controlled to reduce the humidity within the space to the target humidity level based on the target operating time of the desiccant dehumidifier. The heater device may be controlled to provide regeneration air at a substantially constant temperature at an appropriate temperature level. The volumetric flow rate of the regeneration air may be controlled to an appropriate level by controlling the fan. An appropriate level of the temperature of the regeneration air and an appropriate level of the volumetric flow rate of the regeneration air may be selected to reach the target humidity within the space within the target operating time of the desiccant dehumidifier. In the desiccant dehumidifier, a third humidity sensor can be positioned in combination with the first and / or second humidity sensors, and in the desiccant dehumidifier, values ​​from the third humidity sensor can be analyzed in combination with values ​​from the first and / or second humidity sensors.

[0019] The desiccant dehumidifier may further include a dew point sensor disposed within the space fluidly connected to the process air circuit. Controlling the volumetric flow rate of the regeneration air through the regeneration section is further based on a target dew point humidity determined by the dew point sensor. The dew point sensor may be disposed within the space to be dried by the desiccant dehumidifier. The dew point sensor is configured to transmit a signal regarding the dew point detected within the space to the control device. In some situations, it may be important to avoid condensation of fluids on the walls and surfaces of the room. Therefore, the volumetric flow rate of the regeneration air through the regeneration section may be controlled to reach the target dew point humidity. In the desiccant dehumidifier, the dew point sensor may be disposed in combination with the first, second, and / or third humidity sensors.

[0020] The step of controlling the volumetric flow rate of the regeneration air through the regeneration section may include controlling a speed of a fan to control the volumetric flow rate of the regeneration air. The fan may be connected to a control device. The control device may control the speed of the fan to control the volumetric flow rate of the regeneration air through the regeneration section.

[0021] The desiccant dehumidifier may further include a damper disposed downstream of the desiccant rotor in the regeneration air circuit. The step of controlling the volumetric flow rate of the regeneration air through the regeneration section includes controlling the damper to control the volumetric flow rate of the regeneration air. The damper may be controlled to a position between an open position and a closed position. In the fully open position, a large volumetric flow rate of the regeneration air may pass through the regeneration sensor. In a position between the open position and the closed position, the volumetric flow rate of the regeneration air through the regeneration section may be restricted. The damper may be controlled electrically or pneumatically.

[0022] The desiccant dehumidifier may further include a purge air circuit arranged to send purge air through the purge section of the desiccant rotor. The purge air circuit is arranged in fluid communication with the process air circuit upstream of the desiccant rotor and is further arranged with respect to the regeneration air circuit upstream of the heater device. The method further includes controlling the volumetric flow rate of the purge air along with the regeneration air through the desiccant rotor based on a predetermined target humidity within the desiccant rotor. In addition to the process air flow and the regeneration air flow, a purge air flow is also configured to pass through the desiccant rotor. The purge air flow is arranged to flow within the purge air circuit of the desiccant dehumidifier. As the regeneration air flow passes through the rotor, the temperature of the desiccant rotor increases. To effectively capture moisture and water from the process air flow within the desiccant rotor, it is desirable for the regeneration air flow to reduce the temperature of the portion of the desiccant rotor that has passed through the desiccant rotor. Therefore, the purge air flow is directed through the purge section. The temperature of the purge air flowing through the purge section can be lower than the temperature of the regeneration air flow passing through the desiccant rotor. Therefore, the purge air flowing through the purge section reduces the temperature of the portion of the desiccant rotor where the regeneration air flow passed. Because the regeneration air flow increases the temperature of the desiccant rotor, the temperature of the purge air flow increases as it flows through the purge section. The increased-temperature purge air is directed to the regeneration air circuit upstream of the heater device. The heater device can generate a substantially constant and uniformly distributed regeneration air temperature, which can be beneficial for energy recovery in the purge air section. Furthermore, the regeneration air flow can be controlled to achieve a target moisture outlet content by a fan in the regeneration circuit that simultaneously controls the purge air flow. This procedure has two energy-related advantages: the heater device has a flattening effect on the temperature distribution, making it more uniform. Also, since the heat transfer effect in the desiccant rotor remains substantially constant, the combined temperature of the purge outlet air and heated regeneration air remains substantially constant / similar regardless of air flow / volume.

[0023] The step of controlling the volumetric flow rate of the purge air along with the regeneration air through the desiccant rotor may include controlling the speed of a fan to control the volumetric flow rate of the purge air and the regeneration air through the desiccant rotor. The volumetric flow rates of both the purge air and the regeneration air through the desiccant rotor can be controlled by the speed of the fan. The fan can be connected to a control device. The fan is disposed downstream of the desiccant rotor so that the fan can generate negative pressure in the regeneration air circuit and the purge air circuit. The volumetric flow rates of both the purge air and the regeneration air through the desiccant rotor can be controlled by a damper. Furthermore, the volumetric flow rates of both the purge air and the regeneration air through the desiccant rotor can be controlled by the damper along with the selected speed of the fan.

[0024] The step of controlling the volumetric flow rate of the purge air along with the regeneration air through the desiccant rotor may include controlling the volumetric flow rate of the purge air through the purge section of the desiccant rotor relative to the volumetric flow rate of the regeneration air through the regeneration section of the desiccant rotor. Using a predetermined target humidity in the regeneration section of the desiccant rotor, the ratio between the volumetric flow rates of the purge air and the regeneration air can be varied to reach a predefined target. The desiccant dehumidifier's operating mode can either dry the air at low cost or dry the air quickly. For example, to enable the desiccant dehumidifier to dry the air quickly, the desiccant dehumidifier can reduce the ratio between the volumetric flow rates of the purge air and the regeneration air to reach a high drying capacity, e.g., expressed in weight per period. To vary this ratio, the desiccant dehumidifier can be provided with an adjustable purge air inlet. Such an inlet can limit the volumetric flow rate of the purge air as a function of the volumetric flow rate of the regeneration air. A high volumetric flow rate of regeneration air with a low ratio of purge air volumetric flow rate to regeneration air volumetric flow rate can reduce the time to reach a predetermined target humidity.

[0025] The step of controlling the volumetric flow rate of the regeneration air at a substantially constant temperature through the regeneration section based on a predetermined target humidity in the regeneration section of the desiccant rotor may include controlling the volumetric flow rate of the regeneration air at a substantially constant temperature through the regeneration section based on a predetermined target humidity in the regeneration section that is greater than 0% RH. The predetermined target humidity may be a humidity in the regeneration section that is greater than 0% RH. When the humidity in the regeneration section of the desiccant rotor is greater than 0% RH, unnecessary drying of the desiccant rotor due to excessive heating of the desiccant rotor may not occur. Therefore, the cost of heating the regeneration air is reduced. The humidity in the regeneration section may also depend on the axial length or thickness of the rotor, the rotational speed of the rotor, and the volumetric flow rate of the regeneration air through the regeneration section.

[0026] The present disclosure also relates to a computer program comprising instructions. When the program is executed by a data processing unit of a control device of a desiccant dehumidifier, the instructions cause the control device to perform the method disclosed above. The present invention further relates to a computer-readable medium having the computer program stored thereon. The method can be included in pre-programmed software that can be implemented in a generating unit suitable for utilizing the method. The pre-programmed software can be stored in the control device. Alternatively, or in combination, the software can be stored in a memory or computer remote from the control device.

[0027] The above object is also achieved by the desiccant dehumidifier as initially defined. This desiccant dehumidifier further includes the feature that a control device is configured to control the heater device to provide regeneration air at a substantially constant temperature and to control a volumetric flow rate of the regeneration air through the regeneration section based on a predetermined target humidity in the regeneration section of the desiccant rotor. The control device may be configured to control the heater device to provide regeneration air at a constant or substantially constant temperature. The heater device may be powered by electricity. The power to the heater device may be controlled by the control device. The substantially constant temperature of the regeneration air provided by the heater device may be selected based on a selected predetermined target humidity. The selected level of the substantially constant temperature is controlled by the control device. Furthermore, the control device may be configured to control a fan to achieve a volumetric flow rate of the regeneration air through the regeneration section.

[0028] According to one example, the heater device may include a PTC heater. The PTC heater can generate a constant or substantially constant regeneration temperature. Furthermore, the PTC heater can generate a uniformly or substantially uniformly distributed regeneration air temperature in the regeneration section. The regeneration air flow is also controlled by a regeneration air fan to obtain a target moisture outlet content. The PTC heater has a flattening effect on the temperature distribution, making it uniform. PTC is an abbreviation for positive temperature coefficient.

[0029] The predetermined target humidity in the regeneration section of the desiccant rotor can be greater than 0% RH. If the humidity in the regeneration section of the desiccant rotor is greater than 0% RH, unnecessary drying of the desiccant rotor due to excessive heating of the desiccant rotor may not occur. Therefore, the heating cost of the regeneration air is reduced. [Brief explanation of the drawings]

[0030] The above objects, as well as additional objects, features, and advantages of the present disclosure, will be more fully appreciated by reference to the following illustrative, non-limiting detailed description of exemplary embodiments of the present disclosure in conjunction with the accompanying drawings.

[0031] [Figure 1] 1 illustrates a schematic perspective view of a desiccant dehumidifier according to an example; [Figure 2] 1 illustrates a schematic diagram of a desiccant dehumidifier connected to a space or room, according to an example. [Figure 3] 10 illustrates a schematic diagram of a desiccant dehumidifier connected to a space or room, according to another example. [Figure 4] 1 shows a flowchart of a method according to an example. [Figure 5] 1 illustrates a schematic diagram of a control device according to an example. DETAILED DESCRIPTION OF THE INVENTION

[0032] The present disclosure will now be described with reference to the accompanying drawings, in which preferred exemplary embodiments of the present disclosure are shown. However, the present disclosure may be embodied in other forms and should not be construed as limited to the embodiments disclosed herein. The disclosed embodiments are provided so that the scope of the disclosure will be fully conveyed to those skilled in the art.

[0033] FIG. 1 is a perspective view of a schematic representation of a desiccant dehumidifier 1 according to an example embodiment. The desiccant dehumidifier 1 includes a desiccant rotor 2 rotatably disposed about a central axis 4. A process air circuit 6 is disposed to deliver process air 8 through a treatment section 10 of the desiccant rotor 2. A regeneration air circuit 12 is disposed to deliver regeneration air 14 through a regeneration section 16 of the desiccant rotor 2. A purge air circuit 18 is disposed to deliver purge air 20 through a purge section 22. The purge air circuit 18 is disposed in fluid communication with the process air circuit 6 upstream of the desiccant rotor 2 and is further disposed upstream of a heater device 28 relative to the regeneration air circuit 12. The heater device 28 is disposed in fluid communication with the regeneration air circuit 12 upstream of the desiccant rotor 2. The heater device 28 may include a PTC heater. A fan 26 is disposed downstream of the desiccant rotor 2 within the regeneration air circuit 12. The fan 26 is configured to generate a flow of regeneration air 14 within the regeneration air circuit 12. A motor 32 is arranged to rotate the desiccant rotor 2 about the central axis 4 via a transmission 34.

[0034] FIG. 2 schematically illustrates a desiccant dehumidifier 1 connected to a space 80 or room according to an example. In FIG. 2, a desiccant rotor 2 includes a treatment section 10, a regeneration section 16, and a purge section 22. A process air circuit 6 is configured to deliver process air 8 through the treatment section 10. A process fan 9 is disposed in the process air circuit 6 to generate a flow of the process air 8 within the process air circuit 6. A regeneration air circuit 12 is disposed to deliver regeneration air 14 through the regeneration section 16. A purge air circuit 18 is disposed to deliver purge air 20 through the purge section 22. A fan 26 is disposed downstream of the desiccant rotor 2 within the regeneration air circuit 12. A damper 30 is disposed downstream of the desiccant rotor 2 within the regeneration air circuit 12. A heater device 28 is disposed upstream of the desiccant rotor 2 and in fluid communication with the regeneration air circuit 12. The desiccant dehumidifier 1 further includes a first humidity sensor 50 disposed downstream of the desiccant rotor 2 in the process air circuit 6. A second humidity sensor 60 is disposed downstream of the desiccant rotor 2 in the regeneration air circuit 12, and a third humidity sensor 70 is disposed in a space 80 fluidly connected to the process air circuit 6. The desiccant dehumidifier 1 further includes a dew point sensor 90 disposed in the space 80. A control device 200 is connected to the fan 26, the damper 30, the heater device 28, the first, second, and third humidity sensors 50, 60, and 70, and the dew point sensor 90. The damper 30 can be controlled to control the volumetric flow rate of the regeneration air 14 through the regeneration section 16. Furthermore, the volumetric flow rates of both the purge air 20 and the regeneration air 14 through the desiccant rotor 2 can be controlled by the damper 30 in conjunction with a selected speed of the fan 26 disposed in the regeneration air circuit 12.

[0035] 3 is a schematic diagram of a desiccant dehumidifier 1 connected to a space 80 or room according to another example. In FIG. 3, a purge air circuit 18 is disposed in fluid communication with the regeneration air circuit 12 upstream of a heater device 28. The purge air circuit passes through a purge section of the desiccant rotor 2 and is then disposed in fluid communication with the regeneration air circuit 12 downstream of the heater device and upstream of the desiccant rotor 2.

[0036] 4 shows a flowchart of a method according to an example. The method is executed by a control device 200 to control a desiccant dehumidifier 1. The method relates to the desiccant dehumidifier 1 disclosed in FIGS. 1 and 2. To this end, the desiccant dehumidifier 1 comprises a desiccant rotor 2 rotatably arranged about a central axis 4 of the desiccant rotor 1, a process air circuit 6 configured to deliver process air 8 through a treatment section 10 of the desiccant rotor 2, a regeneration air circuit 12 configured to deliver regeneration air 14 through a regeneration section 16 of the desiccant rotor 2, a fan 26 disposed downstream of the desiccant rotor 2 in the regeneration air circuit 12 and configured to generate a flow of the regeneration air 14 within the regeneration air circuit 12, and a heater device 28 disposed upstream of the desiccant rotor 2 in fluid communication with the regeneration air circuit 12.

[0037] The method includes step s101 of controlling the heater device 28 to provide regeneration air 14 at a substantially constant temperature, and step s102 of controlling the volumetric flow rate of the regeneration air 14 at a substantially constant temperature through the regeneration section 16 based on a predetermined target humidity in the desiccant rotor 2.

[0038] The desiccant dehumidifier 1 further includes a first humidity sensor 50 disposed downstream of the desiccant rotor 2 in the process air circuit 6, and step s102 of controlling the volumetric flow rate of the regeneration air 14 through the regeneration section 16 is further based on the current humidity in the desiccant rotor 2 determined by the first humidity sensor 50. The desiccant dehumidifier 1 further includes a second humidity sensor 60 disposed downstream of the desiccant rotor 2 in the regeneration air circuit 12, and step s102 of controlling the volumetric flow rate of the regeneration air 14 through the regeneration section 16 is further based on the current humidity in the desiccant rotor 2 determined by the second humidity sensor 60. The desiccant dehumidifier 1 further includes a third humidity sensor 70 disposed in a space 80 fluidly connected to the process air circuit 6, and step s102 of controlling the volumetric flow rate of the regeneration air 14 through the regeneration section 16 is further based on a target operating time t of the desiccant dehumidifier 1 to reach a target humidity TH in the space 80 determined by the third humidity sensor 70. The desiccant dehumidifier 1 further includes a dew point sensor 90 disposed within the space 80 fluidly connected to the process air circuit 6, and step s102 of controlling the volumetric flow rate of the regeneration air 14 through the regeneration section 16 is further based on a target dew point humidity °DP determined by the dew point sensor 90. Step s102 of controlling the volumetric flow rate of the regeneration air 14 through the regeneration section 16 includes controlling the speed of the fan 26 to control the volumetric flow rate of the regeneration air 14. The desiccant dehumidifier 1 further includes a damper 30 disposed downstream of the desiccant rotor 2 in the regeneration air circuit 12, and step s102 of controlling the volumetric flow rate of the regeneration air 14 through the regeneration section 16 includes controlling the damper 30 to control the volumetric flow rate of the regeneration air 14. Furthermore, the volumetric flow rates of both the purge air and the regeneration air through the desiccant rotor can be controlled by the damper along with the selected fan speeds.

[0039] The desiccant dehumidifier 1 further includes a purge air circuit 18 arranged to deliver purge air 20 through the purge section 22 of the desiccant rotor 2. The purge air circuit 18 is arranged upstream of the desiccant rotor 2 in fluid communication with the process air circuit 6, and is further arranged upstream of the heater device 28 relative to the regeneration air circuit 12. The method further includes step s103 of controlling the volumetric flow rate of the purge air 20 together with the regeneration air 14 through the desiccant rotor 2 based on a predetermined target humidity in the desiccant rotor 2. Step s103 of controlling the volumetric flow rate of the purge air 20 together with the regeneration air 14 through the desiccant rotor 2 includes controlling the speed of the fan 26 to control the volumetric flow rate of the purge air 20 and the regeneration air 14 through the desiccant rotor 2. Step s103 of controlling the volumetric flow rate of the purge air 20 together with the regeneration air 14 passing through the desiccant rotor 2 may include controlling the volumetric flow rate of the purge air 20 passing through the purge section 22 of the desiccant rotor 2 relative to the volumetric flow rate of the regeneration air 14 passing through the regeneration section 16 of the desiccant rotor 2.

[0040] The predetermined target humidity is the humidity in the regenerating section 16 of the desiccant rotor 2, and can be greater than 0% RH.

[0041] 5 schematically illustrates a control device 200 for a desiccant dehumidifier 1 according to an example. The control device 200 includes at least one processor 201 and a computer-readable medium 202. The control device 200 can be configured to perform the method described in FIG. 3 when a computer program is executed by the at least one processor 201. The computer program includes computer-readable instructions that can be stored on the computer-readable medium 202, such as a non-transitory hardware memory device of the control device 200.

Claims

1. A method performed by a control device (200) for controlling a desiccant dehumidifier (1), comprising: The desiccant dehumidifier (1) a desiccant rotor (2) arranged rotatably around a central axis (4) of the desiccant rotor (2); a process air circuit (6) configured to direct process air (8) through a treatment section (10) of the desiccant rotor (2); a regeneration air circuit (12) configured to send regeneration air (14) through a regeneration section (16) of the desiccant rotor (2); a fan (26) disposed downstream of the desiccant rotor (2) in the regeneration air circuit (12), the fan (26) configured to generate a flow of regeneration air (14) in the regeneration air circuit (12); a heater device (28) disposed in fluid communication with the regeneration air circuit (12) and upstream of the desiccant rotor (2); This method is controlling (s101) the heater device (28) to provide the regeneration air (14) at a substantially constant temperature; controlling (s102) a volumetric flow rate of the regeneration air (14) at the substantially constant temperature passing through the regeneration section (16) based on a predetermined target humidity in the regeneration section (16) of the desiccant rotor (2); A method comprising:

2. The desiccant dehumidifier (1) further comprises a first humidity sensor (50) disposed in the process air circuit (6) downstream of the desiccant rotor (2); 2. The method of claim 1, wherein the step (s102) of controlling the volumetric flow rate of the regeneration air (14) through the regeneration section (16) is further based on a current humidity in the desiccant rotor (2) determined by the first humidity sensor (50).

3. The desiccant dehumidifier (1) further comprises a second humidity sensor (60) disposed downstream of the desiccant rotor (2) in the regeneration air circuit (12); 3. The method according to claim 1, wherein the step (s102) of controlling the volumetric flow rate of the regeneration air (14) through the regeneration section (16) is further based on the current humidity in the desiccant rotor (2) determined by the second humidity sensor (60).

4. The desiccant dehumidifier (1) further comprises a third humidity sensor (70) disposed in a space (80) fluidly connected to the process air circuit (6); 4. The method according to claim 1, wherein the step (s102) of controlling the volumetric flow rate of the regeneration air (14) through the regeneration section (16) is further based on a target operating time (t) of the desiccant dehumidifier (1) for reaching a target humidity (TH) in the space (80) determined by the third humidity sensor (70).

5. The desiccant dehumidifier (1) further comprises a dew point sensor (90) disposed within a space (80) fluidly connected to the process air circuit (6); 5. The method of claim 1, wherein the step (s102) of controlling the volumetric flow rate of the regeneration air (14) through the regeneration section (16) is further based on a target dew point humidity (°DP) determined by the dew point sensor (90).

6. 6. The method of claim 1, wherein the step (s102) of controlling the volumetric flow rate of the regeneration air (14) through the regeneration section (16) comprises controlling the speed of the fan (26) to control the volumetric flow rate of the regeneration air (14).

7. The desiccant dehumidifier (1) further comprises a damper (70) disposed downstream of the desiccant rotor (2) in the regeneration air circuit (12); 7. The method according to claim 1, wherein the step (s102) of controlling the volumetric flow rate of the regeneration air (14) through the regeneration section (16) comprises controlling the damper (70) to control the volumetric flow rate of the regeneration air (14).

8. The desiccant dehumidifier (1) further comprises a purge air circuit (18) arranged to send purge air (20) through the purge section (22) of the desiccant rotor (2); the purge air circuit (18) is disposed in fluid communication with the process air circuit (6) upstream of the desiccant rotor (2), and further disposed with respect to the regeneration air circuit (12) upstream of the heater device (28); 8. The method according to claim 1, further comprising the step (s103) of controlling a volumetric flow rate of the purge air (20) together with the regeneration air (14) passing through the desiccant rotor (2) based on the predetermined target humidity in the desiccant rotor (2).

9. 9. The method of claim 8, wherein the step (s103) of controlling the volumetric flow rate of the purge air (20) together with the regeneration air (14) through the desiccant rotor (2) comprises controlling a speed of the fan (26) to control the volumetric flow rate of the purge air (20) and the regeneration air (14) through the desiccant rotor (2).

10. 10. The method according to claim 8, wherein the step (s103) of controlling the volumetric flow rate of the purge air (20) together with the regeneration air (14) passing through the desiccant rotor (2) comprises controlling the volumetric flow rate of the purge air (20) passing through a purge section (22) of the desiccant rotor (2) relative to the volumetric flow rate of the regeneration air (14) passing through the regeneration section (16) of the desiccant rotor (2).

11. 11. The method according to claim 1, wherein the step (s102) of controlling the volumetric flow rate of the regeneration air (14) at the substantially constant temperature through the regeneration section (16) based on a predetermined target humidity in the regeneration section (16) of the desiccant rotor (2) comprises controlling the volumetric flow rate of the regeneration air (14) at the substantially constant temperature through the regeneration section (16) based on a predetermined target humidity in the regeneration section (16) that is higher than 0% RH.

12. A computer program comprising instructions, 12. A computer program, the instructions of which, when executed by a data processing unit (201) of a control device (200) of a desiccant dehumidifier (1), cause the control device (200) to perform the method of any one of claims 1 to 11.

13. A computer readable medium (202) having stored thereon the computer program of claim 12.

14. a desiccant rotor (2) arranged rotatably around a central axis (4) of the desiccant rotor (1); a process air circuit (6) configured to direct process air (8) through a treatment section (10) of the desiccant rotor (2); a regeneration air circuit (12) configured to send regeneration air (14) through a regeneration section (16) of the desiccant rotor (2); a fan (26) disposed downstream of the desiccant rotor (2) in the regeneration air circuit (12), the fan (26) configured to generate a flow of regeneration air (14) in the regeneration air circuit (12); a heater device (28) disposed in fluid communication with the regeneration air circuit (12) and upstream of the desiccant rotor (2); a control device (200); The control device (200) controls the heater device (28) to provide the regeneration air (14) at a substantially constant temperature, and is configured to control a volumetric flow rate of the regeneration air (14) through the regeneration section (16) based on a predetermined target humidity in the regeneration section (16) of the desiccant rotor (2). Desiccant dehumidifier (1).

15. 15. The desiccant dehumidifier (1) of claim 14, wherein the heater device (28) comprises a PTC heater.

16. 16. The desiccant dehumidifier (1) according to any one of claims 14 and 15, wherein the predetermined target humidity in the regenerating section (16) of the desiccant rotor (2) is greater than 0% RH.

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