CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Patent Application No. 63/391,904, filed July 25, 2022, and entitled “REACTIVATION ROTOR INLET STRATIFICATION OUTLIER DETECTION SENSOR,” the entirety of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

[0002] The present invention relates generally to heating, ventilating, and air conditioning (HVAC) systems and methods, and more specifically to air conditioning, dehumidification, or drying systems that incorporate a thermally activated desiccant wheel. The present invention also provides improved and efficient use of energy consumed while using desiccant wheel systems. Description of the Related Art

[0003] Dehumidification is defined as a process of removing moisture from air, and several methods of dehumidifying air are known. Those commonly utilized involve refrigeration, desiccants, or both. In the case of dehumidification using refrigeration, moisture from an airstream passed over a cooling coil condenses, thereby reducing the moisture in the air stream. In the case of dehumidification using desiccants, the process is one of absorption or adsorption. For absorption, either liquid or solid desiccants are used, typically halide salts or solutions. For adsorption, solid desiccants like silica gel, activated alumna, molecular sieve, etc., are used. [0004] Some desiccant dehumidifier units are of the rotary type, a schematic view of which is shown in FIG. 19. In a typical rotary-type dehumidifier unit 10, the desiccant is contained in a rotary bed, also referred to as a desiccant rotor or desiccant wheel 12. The desiccant wheel 12 moves on a continuous or intermittent basis through, in its simplest form, two compartments or sectors, one for process 1 and the other for regeneration 2. The air to be dried is generally referred to as process air and the air used to regenerate the desiccant is referred to as regeneration or reactivation air. The terms regeneration and reactivation will be used interchangeably in this specification. In the process sector 1, the process air 14 driven by a process fan or blower 24 passes through the rotating wheel 12 and is dried by contact with the desiccant. In regeneration, air is brought in, generally from atmosphere, passed over a heat source 18 to elevate (raise) its temperature, and then passed as regeneration air 16 through the remaining portion of the wheel, that is, the reactivation or regeneration sector 2, by means of a regeneration fan or blower 26. This heats the wheel 12 and drives out the water content, thus enabling the wheel to adsorb more moisture in the reactivated portion of the wheel. As desiccant dehumidifier systems inherently use a significant amount of heat energy for regeneration, efforts have been made to find ways to reduce the amount of heat used by the system.

[0005] The regeneration heat input source 18 may be electric, steam, gas, or oil burner, thermal fluid such as hot water, refrigeration condenser heat, recovered heat from another process, or any combination of these that can heat the reactivation air to the temperature required for the application. In some known dehumidification systems, the heat source 18 is in the form of a heater sub-assembly. In order to effectively regenerate the wheel 12, depending on the desiccant, the heat source 18 must elevate the temperature of the regeneration air 16 to very high temperatures, in the range of 300 to 400° F, for example. In some examples in this disclosure, the target temperature for the regeneration air at the wheel interface is 325° F, although this is merely an example and is not intended to be limiting. Examples of heater sub-assemblies include direct fire gas (DFG), indirect fire gas (IDFG), and electric heater sub-assemblies. Glowing heating elements of electric heater sub-assemblies have radiative heat emission that, in direct line-of-sight without any intervening structure, can reach 1000° F measured at close proximities to the wheel at low regeneration air flow. The tubes on the IDFG heater sub-assembly can glow and emit light as well. These radiative temperatures that far exceed the target regeneration temperatures can have a deleterious effect on the wheel 12. To prevent radiative heat exposure on the facial surface of the wheel 12, a louvered partition or radiation screen 22 has been positioned between heat source 18 and wheel 12 so as to obstruct the line-of-sight between the heat source 18 and the face of the wheel 12.

[0006] An example of an existing radiation screen is shown in FIGS. 20A-20C. FIG. 20A is a plan view of a known radiation screen 22 used in a heater sub-assembly of a dehumidifier system, FIG. 20B is a perspective view of the radiation screen, and FIG. 20C is a partial cross- sectional view along section line XXC-XXC in FIG. 20A. In this solution, a plate 30 of a material such as sheet metal is positioned in the ductwork of the heater sub-assembly between the heat source 18 and the wheel 12. The plate 30 includes a series of louvers 32 forming through-holes that allow the heated regeneration air 16 to pass through the screen 22, but block the line-of-sight between the heat source and the wheel. In the shown screen 22, the louvers 32 are positioned in arrays of multiple vertical lines and the louvers are designed such that all louvers 32a in one column are angled downwardly, while all louvers 32b in columns adjacent to the one column are angled upwardly. In one example, in a screen 22 formed of a plate 30 having a width of 39 inches and a height of 25 inches, the louvers are aligned in 61 rows and 25 columns for a total of 1275 louvers. The louvers can be angled at 30° from vertical, either upwardly or downwardly, with the upwardly angled louvers and the downwardly angled louvers differing by 180°. Alternatively, a mean screen can be positioned at an angle for the same purpose.

[0007] One concern in supplying reactivation air to the wheel 12 is stratification, in which layers of reactivation air have significantly different temperatures. The inventor has determined that a main cause of temperature stratification formation in industrial dehumidification units, such as those with an IDFG sub-heater assembly, is the single-size louver perforations used on all unit sizes. While the alternating louver design in a typical radiation screen 22 is intended to mix the stratified air arriving from the heating source before reaching the wheel 12, it has been found that significant stratification issues can still occur. The inventor has found through various testing under differing conditions that this problem is more pronounced in certain conditions.

Modulating the reactivation fan 26 can reach low air capacity thresholds, and low air volumes are necessary on low dew point units. At low air volumes, air mixing may not be effectively achieved by the radiation screen 22 and in recent tests it was shown that the louvers can, in fact, intensify stratification under certain conditions. Variations in the design of the ductwork between the heat source and the wheel can also affect stratification.

[0008] FIG. 21 depicts test results representing the level of stratification at the rotor inlet when using a current state-of-the-art radiation screen 22. Testing was performed with the radiation screen having the dimensions and louver design described above, and a grid of 24 thermocouples was positioned two inches from the face of the reactivation sector of wheel 12. See FIG. 14. The grid included nine rows of thermocouples TC1-TC24 spaced a few inches apart, with each row including one to four thermocouples. The top row consisted of thermocouple Nos. TC1-TC4 and the bottom row consisted of single thermocouple No. TC24. The testing included feedback control (to be described later) using a single point sensor for a target temperature of 325° F at the rotor reactivation inlet. As can be seen in FIG. 21, the radiation screen induced a stratified layer profile (coupled with varying velocity vectors) which was not uniform. Incidentally, in the testing, the single point sensor for feedback control was placed close to thermocouple No. TC5.

[0009] Reactivation air heating control on many industrial dehumidification units is performed by a programmable logic controller (PLC) using cascade control of proportional-integral- derivative (PID) loops, that is, control loops employing feedback widely used in industrial control systems requiring continuously modulated control. See FIG. 18. A singular thermocouple point sensor is often used to measure the heat profile of reactivation flow into the rotor, whereas a similar setup of a singular thermocouple point sensor placement is used on the reactivation outlet, usually but not exclusively, after a blow-through reactivation fan 26. This post-fan position often can induce enough mixing to provide appropriate averaging of the reactivation outlet temperature. The sensor at the rotor inlet is positioned at a location in the airstream for a specific air flow. The sensor is positioned based on the unit configuration to best represent the temperature profile formation on the respective unit in which it is installed.

[0010] The cascade control in the PLC involves the use of two discrete control loops, such as PID control loops, and continuously calculates an error value as the difference between a desired setpoint SP and a process variable PV. The PLC can employ two processing sections Cl, C2. The first control loop provides the set point for the second PID control loop. The thermocouple sensors at the reactivation rotor inlet and outlet, as shown in the schematic diagram in FIG. 18, are both an integral part of the cascading PID loop functionality. The loop set point SP (TSET) is the required temperature TSET to be maintained for the reactivation process. The primary process (outer process loop) is the reactivation air after the reactivation fan, and the secondary process (inner process loop) is the reactivation air after the heater, that is, before entering the rotor. The primary process variable is temperature measurement TE2 after the reactivation fan and the secondary process variable is temperature measurement TEi after the heater and before the rotor. The primary PID loop compares TE2 (indirect measurement of the secondary PID loop control variable) with the set point TSET and calculates an output value to be compared by the secondary PID loop. The secondary PID loop modulates the heater actuator with an output signal TOUT based on TEi measurements compared to the primary PID loop control variable. The reactivation temperature TE2 at the rotor inlet sensor is used as the reciprocal feed to the reactivation PID control by the PLC, while a high temperature event is detected using an industrial grade latching limit switch.

[0011] The current sensor type used in many industrial dehumidifier units is a point thermocouple sensor (either iron-constantan or chromel-alumel type) enclosed in a stainless steel sheath. However, such a single-point sensor is not suited to determine the effective temperature of stratified air across the whole surface of the reactivation zone of wheel 12. Controlling the unit reactivation (temperature of air as it approaches the rotor inlet) based on a specific stratified layer measurement instead of a ground truth value (weighted average temperature) can lead to a) high energy use when the sensor portrays a lower temperature than that actually supplied (ground truth temperature representation) from the heating source, or b) lower rotor efficiency due to sensor portrayal of higher temperature detection than that actually supplied from the heating source. That is, temperature profile misrepresentation due to stratification can cause high energy use or reduced wheel performance due to heater modulating to higher or lower kilowatt outputs, respectively. [0012] With stratification formed near the inlet to the reactivation surface of the wheel 12, use of the single sheath encapsulated duplex thermocouple sensor at that location will have adverse effects on the cascading loop performed by the PLC. The following issues arise with current state-of-the-art methodology in handling stratification elimination and temperature measurement in the reactivation inlet stream:

[0013] i. A single point temperature thermocouple at the rotor cross-sectional reactivation inlet area cannot accurately represent a stratified temperature profile, thus requiring stratification attenuation and/or more accurate temperature representation.

[0014] ii. Misrepresentation of rotor inlet temperature due to stratification formation downstream of the radiation screen has the potential to reduce unit moisture removal efficiency (if the temperature profile representation is higher than a ground truth value) and/or increase energy cost and the unit’s life cycle carbon footprint (if the temperature profile representation is lower than the ground truth value).

[0015] iii. While directional louver perforations in a radiation screen for radiation heat protection can be effective with non-modulating reactivation fans, high speed flow through heating elements, and not-to-exceed external static pressure restrictions on ducting in the reactivation air path, this solution is significantly less effective in applications that require reactivation fan modulation and/or slower flow through the heating elements as stratification at the rotor inlet is more pronounced, particularly with IDFG heat source units.

[0016] iv. Current reactivation inlet temperature readings do not have anomaly detection algorithms running to validate the sensor functionality.

[0017] Since high temperatures at the reactivation inlet location can be detrimental for the rotor composition functionality, a not-to-exceed limit temperature is a factor of consideration. This feature is currently effected in some systems by a duplex thermocouple where both independent sensing elements are located at the tip of a stainless steel sheath. As a safety feature a separate (separate from the PLC) limit switch is connected to the duplex thermocouple as a conditional (threshold set) safety feature. Its duplex capability raises the following concerns: a. A latched high limit switch alarm can be induced by a limit switch if the sensing element is positioned at a prevailing high temperature stratified layer, and this may result in false nuisance trips by maintenance personnel. b. Presence of a directional louver radiation heat protection screen has been used successfully in the past with non-modulating reactivation fans and a not-to-exceed external static pressure restriction on ducting placed on the reactivation air cycle. As the technology develops into more applications that require reactivation fan modulation, air profiles that generate stratification at the rotor inlet are being commonly found. Accounting for stratification formation and attenuating it is important; however, a need for a risk mitigation measure of a ground truth temperature value will be needed regardless of the mechanical attenuation of stratified air formation. Decoupling ground truth measurement from a mechanical root cause solution is a risk due to the following factors:

1. Multiple heater setups/sizes will require multiple mechanical mixing solutions. Testing all of these solutions will result in a safety factor associated with defined boundary conditions.

2. In certain studies, it has been shown that varying ducting profiles to and from the reactivation sector can change the stratification profile on the face of the rotor and increase the potential of a point temperature process value misrepresentation. 3. Low-low non-latched alarms can be induced by a PLC if the sensing element is positioned at a prevailing low temperature stratified layer.

[0018] Although the foregoing discussion has described thermal stratification at the reactivation inlet, the inventor has also found that, depending on various factors in the design and operation of the system, temperature and/or moisture stratification can occur at any cross-sectional location along the reactivation and process airstreams. For example, moisture stratification can exist at the outlet of the process side of the wheel 12, which can lead to ineffective and inefficient dehumidification performance. It has been found, for example, that the flutes in the rotor can cause the moisture stratification.

[0019] Improvements in dehumidification effectiveness and efficiency are desired.

SUMMARY OF THE INVENTION

[0020] This invention is intended to decrease temperature and moisture stratification at the regeneration inlet side (and, consequently, the reactivation outlet side) or the process outlet side of a rotor, such as a rotor used in dehumidifiers. This invention is also intended to improve temperature profile measurement at the regeneration inlet side. Such will improve dehumidification effectiveness and efficiency, thereby reducing energy consumption and costs.

[0021] According to one aspect of the present invention, a fluid processing system for treating a fluid includes a rotor having at least a process segment through which a process fluid stream is directed in a process flow direction and a regeneration segment through which a regeneration fluid stream is directed in a regeneration flow direction; a heating device for heating the regeneration fluid stream upstream of the regeneration segment of the rotor; a blowing device disposed on one side of the rotor for causing movement of the regeneration fluid stream or the process fluid stream; a first temperature sensing unit disposed in the regeneration fluid stream upstream of the regeneration segment of the rotor between the heating device and the rotor, the first temperature sensing unit including plural first temperature sensing elements arranged at spaced locations adjacent a regeneration inlet of the rotor; a second temperature sensing unit disposed downstream of the regeneration segment of the rotor and including at least one second temperature sensing element; a controller for controlling at least one of the rotor, the heating device, and the blowing device based on first temperature information from the first temperature sensing unit and second temperature information from the second temperature sensing unit; and a baffle section disposed on the other side of the rotor opposite the blowing device and configured to disrupt the regeneration fluid stream or the process fluid stream, the baffle section including at least three opposed baffle plates disposed transverse to a primary flow direction of the fluid stream, a distal end of one of the baffle plates extending into the fluid stream beyond a distal end of an adjacent one of the baffle plates so as to prevent a direct line-of- sight through the baffle section.

[0022] According to another aspect of the present invention, a fluid processing system for treating a fluid includes a rotor having at least a process segment through which a process fluid stream is directed in a process flow direction and a regeneration segment through which a regeneration fluid stream is directed in a regeneration flow direction; a heating device for heating the regeneration fluid stream upstream of the regeneration segment of the rotor; a blowing device disposed on one side of the rotor for causing movement of the regeneration fluid stream or the process fluid stream; and a baffle section disposed on the other side of the rotor opposite the blowing device and configured to disrupt the regeneration fluid stream or the process fluid stream, the baffle section including at least three opposed baffle plates disposed transverse to a primary flow direction of the fluid stream, a distal end of one of the baffle plates extending into the fluid stream beyond a distal end of an adjacent one of the baffle plates so as to prevent a direct line-of-sight through the baffle section.

[0023] According to yet another aspect of the present invention, a fluid processing system for treating a fluid includes a rotor having at least a process segment through which a process fluid stream is directed in a process flow direction and a regeneration segment through which a regeneration fluid stream is directed in a regeneration flow direction; a heating device for heating the regeneration fluid stream upstream of the regeneration segment of the rotor; a blowing device disposed on one side of the rotor for causing movement of the regeneration fluid stream or the process fluid stream; and a baffle section disposed on the other side of the rotor opposite the blowing device and configured to disrupt the regeneration fluid stream or the process fluid stream, the baffle section including opposed baffle plates disposed transverse to a primary flow direction of the fluid stream, each of the baffle plates including a base end and a distal end, and each of the baffle plates extending into the fluid stream in a direction inclined at an angle directed upstream into the fluid stream.

[0024] According to still another aspect of the present invention, a fluid processing system for treating a fluid includes a rotor having at least a process segment through which a process fluid stream is directed and a regeneration segment through which a regeneration fluid stream is directed; a heating device for heating the regeneration fluid stream upstream of the regeneration segment of the rotor; a blowing device disposed on one side of the rotor for causing movement of the regeneration fluid stream or the process fluid stream; and a baffle section disposed on the other side of the rotor opposite the blowing device, the baffle section being configured to disrupt the regeneration fluid stream or the process fluid stream, the baffle section comprised of at least one baffle unit including plural slots disposed about a center, each slot forming a through-passage at an angle transverse to a primary flow direction of the fluid stream.

[0024.1] According to still yet another aspect of the present invention, a fluid processing system for treating a fluid includes a rotor having at least a process segment through which a process fluid stream is directed and a regeneration segment through which a regeneration fluid stream is directed; a heating device for heating the regeneration fluid stream upstream of the regeneration segment of the rotor; a blowing device disposed downstream of the regeneration segment of the rotor for causing movement of the regeneration fluid stream; a first temperature sensing unit disposed in the regeneration fluid stream upstream of the regeneration segment of the rotor between the heating device and the rotor, the first temperature sensing unit including plural first temperature sensing elements arranged at spaced locations adjacent a regeneration inlet of the rotor; a second temperature sensing unit disposed downstream of the regeneration segment of the rotor and including at least one second temperature sensing element; and a controller for controlling at least one of the rotor, the heating device, and the blowing device based on first temperature information from the first temperature sensing unit and second temperature information from the second temperature sensing unit.

[0024.2] According to another aspect of the present invention, a control method is provided for controlling a fluid processing system for treating a fluid, the system including a rotor having at least a process segment through which a process fluid stream is directed in a process flow direction and a regeneration segment through which a regeneration fluid stream is directed in a regeneration flow direction, a heating device for heating the regeneration fluid stream upstream of the regeneration segment of the rotor, a blowing device disposed on one side of the rotor for causing movement of the regeneration fluid stream or the process fluid stream, a first temperature sensing unit disposed in the regeneration fluid stream upstream of the regeneration segment of the rotor between the heating device and the rotor, the first temperature sensing unit including plural first temperature sensing elements arranged at spaced locations adjacent a regeneration inlet of the rotor, and a second temperature sensing unit disposed downstream of the regeneration segment of the rotor and including at least one second temperature sensing element. The method includes controlling at least one of the rotor, the heating device, and the blowing device based on first temperature information from the first temperature sensing unit and second temperature information from the second temperature sensing unit.

[0025] A better understanding of these and other aspects of the present invention may be had by reference to the drawings and to the accompanying description, in which preferred embodiments of the invention are illustrated and described.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] FIG. 1 is a perspective view of an embodiment of a dehumidifier unit according to the present invention.

[0027] FIG. 2 is cross-sectional view of the region proximate the desiccant wheel and including the sub-heater assembly in the embodiment of the dehumidifier unit according to the present invention.

[0028] FIG. 3 is a perspective view of a baffle section in the embodiment of the dehumidifier unit according to the present invention.

[0029] FIG. 4 is a cross-sectional view along section line IV-IV in FIG. 3. [0030] FIG 5 is a cross-sectional view of a modified baffle section in the embodiment of the dehumidifier unit according to the present invention.

[0031] FIG. 6 is a perspective view of a modified baffle for use in baffle sections in the embodiment of the dehumidifier unit according to the present invention.

[0032] FIG. 7 is cross-sectional view of the region proximate the desiccant wheel and including a baffle section in the process flow in another embodiment of the dehumidifier unit according to the present invention.

[0033] FIG. 8 is a plan view of an alternative baffle section.

[0034] FIG. 9 is a perspective view of a baffle unit of the alternative baffle section.

[0035] FIG. 10 is an enlarged perspective view of the baffle unit of the alternative baffle section.

[0036] FIG. 11 depicts comparative test results of temperatures at the rotor inlet when using baffle sections according to the present invention and a known radiation screen.

[0037] FIG. 12 depicts a temperature sensor according to an embodiment of the present invention.

[0038] FIG. 13 depicts the temperature sensor arranged in the dehumidifier unit according to the present invention.

[0039] FIG. 14 shows an arrangement of temperature sensors for determining ground-truth temperatures in testing.

[0040] FIG. 15 is a schematic diagram of a rotor dehumidification system.

[0041 ] FIG. 16 is a schematic diagram of control of the present invention.

[0042] FIG. 17 is a schematic diagram of the temperature sensor according to an embodiment of the present invention.

[0043] FIG. 18 is a diagram showing cascading PID loop control. [0044] FIG. 19 is a schematic view of a known rotary-type dehumidifier system.

[0045] FIG. 20A is an elevation view of a known radiation screen used in a heater sub-assembly of a dehumidifier system.

[0046] FIG. 20B is a perspective view of the radiation screen.

[0047] FIG. 20C is a partial cross-sectional view along section line XXC-XXC in FIG. 20A.

[0048] FIG. 21 depicts test results representing the level of stratification at the rotor inlet when using a current state-of-the-art radiation screen.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0049] The present invention will now be described with reference to the accompanying drawings, which are illustrative of certain embodiments of the invention. Variations and modifications are possible without departing from the spirit and scope of the invention.

[0050] FIGs. 1-4 illustrate a first embodiment of the present invention. In particular, FIG. 1 is a perspective view of an embodiment of a dehumidifier unit according to the present invention; FIG. 2 is cross-sectional view of the region approximate the desiccant wheel and including the sub-heater assembly in the dehumidifier unit; FIG. 3 is a perspective view of a baffle section in the dehumidifier unit; and FIG. 4 is a cross-sectional view of the baffle section taken along section line IV-IV in FIG. 3. In the figures, the direction of flow is designated as the 4-z (or -z) direction, the horizontal direction transverse to the direction of flow as the +X (or -x) direction, and the vertical direction as the +y (or -y) direction. In the following description, the reactivation air flows in the +z direction and the process air flows in the -z direction, but such is not intended to be limiting. [0051 ] Referring first to FIG. 1 , the main components and the overall operation of dehumidification unit 100 according to an embodiment of the present invention will be described. As with the prior art dehumidification unit 10 shown in FIG. 19, dehumidification unit 100 includes a desiccant rotor 112, a reactivation heater 118, a process blower or fan 124 for moving process air 114, and a reactivation blower or fan 126 for moving reactivation air 116. The various components of the dehumidifier unit 100 are preferably housed in housing 130. A sub-heater assembly 140 is disposed upstream of desiccant wheel 112 with respect to the direction of flow of the reactivation air (+z direction) and includes reactivation heater 118. The reactivation heater 118 can be any one of direct fire gas (DFG), indirect fire gas (IDFG), and electric heater types, in some of which light radiation is emitted from the heating elements or glowing heat tubes. Ductwork 142 is provided to guide the reactivation air from its source, such as outside air, to the desiccant wheel 112. Heat source 118 can be provided within ductwork 142. In the shown embodiment, the cross-section of the duct work is either rectangular or square shaped in its upstream sections, but transitions to a triangular or pie shape so as to direct the reactivation air to the reactivation sector 102 of desiccant wheel 112.

[0052] As with the desiccant dehumidifier unit 10 described with respect to FIG. 19, the wheel 112 moves on a continuous or intermittent basis through the two sectors, the process sector or zone 101 and the regeneration sector or zone 102. However, the present invention is not limited to this arrangement. Often, another sector is added between the process and regeneration sectors, and is referred to as a purge sector. A third airstream (generally called the purge air) is passed through the purge sector and becomes a portion of the regeneration air. The incorporation of the purge sector helps to recover some residual heat from the rotating wheel 112 before it enters the process sector, thereby reducing the overall energy requirement for regeneration, as well as improving the overall moisture removed by the wheel 1 12. Other sectors, such as isolation sectors, can also be incorporated and are well-known to those of skill in the art.

[0053] Rather than providing a radiation screen as discussed above with respect to FIGs. 20A- 20C, the present invention utilizes a baffle section 122 in order to both block line-of- sight radiation from heat source 118 and mix the reactivation air before reaching desiccant wheel 112 in order to minimize stratification of temperature layers. Baffle section 122 is disposed between sub-heater assembly 140 and the reactivation sector 102 of wheel 112.

[0054] Baffle section 122 is designed to maximize its thermo-hydraulic benefits. For example, the baffle section 122 is designed to both induce turbulent flow in a channel and prevent line-of- sight through the channel. This can be achieved by using plural transverse baffle plates 126 within ductwork 142. Baffle plates 126 can be formed of the same material as the ductwork 142, such as galvanized steel, and be directly attached to the ductwork. Alternatively, baffle plates 126 can be formed in a modular unit that can be inserted in the ductwork 142, the modular unit being sized to fit various ductwork dimensions. In the following discussion, the top, bottom, and side walls can mean walls of either the ductwork or of the modular unit. The baffle plates can be attached to the ductwork in any known manner, as would be understood by those of ordinary skill in the ait.

[0055] At least two, and preferably, at least three, baffle plates 126 are provided, and they can be oriented to extend from the top and bottom of ductwork 142 or from opposite sides of the ductwork, or a combination of from the top and bottom and from opposite sides of the ductwork. Each baffle plate can be attached to the ductwork at its base end and have a free, distal end in the fluid flow. In order to preclude line-of- sight from the heating elements of heat source 118 to the desiccant wheel 112, the opposed baffle plates 126 should extend the full dimension of the ductwork in one direction, and overlap one another in the other direction. For example, if extending from the top and bottom walls, it is important that the width of the baffle plates 126 in the x (horizontal) direction be as wide as the ductwork or at least as wide as the array of heating elements of heat source 118, and that the distal ends overlap in the y (vertical) direction so as to preclude line-of sight from the heating elements to the wheel 112. Likewise, if extending from opposite side walls, it is important that the height of the plates in the y direction be as high as the ductwork or at least as high as the array of heating elements of heat source 118 and that the distal ends overlap in the x (horizontal) direction.

[0056] Variation of the baffle plate angle inclination has been found to promote dynamic behavior of the fluid upstream of the baffle section 122. Angles (a) of the baffle plates 126 between 0° and 45° have been found to be most effective, depending on the flow conditions. For baffle plates 126 extending from the top and bottom sides of the ductwork 142, angle a is defined as the angle of inclination from vertical (y) in the upstream (-x) direction. That is, the baffle plates 126 are angled with their leading edges directed into the airstream. The shape of the baffle and the angle of inclination have been shown in testing to be critical, showing that baffle skin friction was improved by 9.91% in the case of a=15°, to more than 16% in the cases of a = 0°, 15°, 30°, and 45°. As shown in FIGs. 3 and 4, in one example embodiment, three baffle plates 126 (126a- 126c) inclined in the upstream direction are provided in the apparatus. Inclined baffle plates 126 are designed to combine three heat transfer techniques: boundary layer separation, internal flow swirls, and jet impingement, which is a complex flow phenomenon with distinct flow domains and complex flow interactions with a target surface.

[0057] The baffle section 122 will promote stratification attenuation, dedicate velocity profiles to the rotor inlet, improve the accuracy of stratification prediction, and prevent line-of-sight from the heating elements to the desiccant wheel 1 12 surface. The reactivation air mixing caused by baffle section 122 results in sufficient attenuation of stratification of the reactivation air to allow for acceptably accurate measuring of ground truth prevailing temperature experienced by desiccant wheel 112. This is particularly true when used with an averaging sensor to be discussed below. This, in turn, will allow for increased controllability of the reactivation cascading PID loop, maintain the dehumidification unit 100 at its intended performance, improve the limit switch accuracy (reduce nuisance trips), and provide a method to auto test the adherence of the read temperature to the sensing element ground truth level.

[0058] The baffle section 122 has been described as being integrated with the ductwork 142 of the reactivation air flow or as a modular unit. When integrated with the ductwork, the baffle section 122 can be installed as the dehumidifier unit is being constructed on location. When the baffle section 122 is manufactured as a modular unit, an existing dehumidifier can be retrofitted, with the modular baffle section either being installed after removing a section of the existing ductwork 142 or by installing the modular baffle section 122 within the ductwork. In the latter case, the modular baffle section 122 can be provided with seals 128 to ensure airtightness within the ductwork 142. The baffle section 122 can be installed in a transition section of the ductwork.

[0059] The inventor has tested different baffle configurations in a dehumidification unit and compared them to a dehumidification unit utilizing a radiation screen and the results are shown in FIG. 11. One tested baffle configuration is as shown in FIG. 4. In the testing, the previously- described grid of 24 thermocouples (see FIG. 14) was positioned two inches from the face of the reactivation sector 102 of wheel 112. As shown in FIG. 14, the grid included nine rows of thermocouples spaced a few inches apart, with each row including one to four thermocouples.

The top row consisted of thermocouple Nos. 1-4 and the bottom row consisted of single thermocouple No. 24. The testing included feedback control using a single point sensor for a target temperature of 325° F at the rotor reactivation inlet and at two reactivation fan speeds, at 45 Hz for low reactivation flow and 50 Hz for high reactivation flow. Using measurement results from the 24 thermocouples, the temperature profile at the desiccant wheel reactivation inlet face was determined from three perspectives: total average, weighted average based on reactivation cross-sectional area, and weighted average based on quasi-measurement of air speeds.

[0060] In FIG. 11, the testing results show the temperature ranges for all three perspectives using the following abbreviations:

[0061] NWA: Non- weighted averaging (averaged without sensor placement consideration) [0062] AWA: Area based weighted averaging (weighted averaging (area based) with sensor placement consideration)

[0063] SAW: Air-capacity based averaging (weighted averaging (flow velocity based) with sensor placement consideration)

[0064] For the subscripts, B: Baffle configuration (of the present invention), and RS: radiation screen (as known in the art)

[0065] As shown in FIG. 11, the results across all three perspectives when using baffle section 122 were much closer to the target temperature of 325° F than the results when using the radiation screen. The baffle configuration shown in FIG. 4 had results closest to the target temperature.

[0066] Improving thermal mixing using the baffle section 122 will result in some pressure drop in the reactivation flow. For example, in one test, the pressure drops across baffle section 122 and the radiation screen were measured as 0.32” H2O, and 0.16” H2O, respectively. Another modification of the baffle system is to construct the baffles from corrugated plates 126’ as shown in FIG. 6. The inventor has found that corrugated plates can reduce pressure losses due to improved undulation. That is, the corrugated walls improve the hydraulic performance of the baffle system by increasing the factor of slip.

[0067] As noted above, the mixing effectiveness of the baffle system is based on several factors, including the angle of the baffles 126 and the flow rate of the reactivation air. As the reactivation flow rate may be modulated in some systems, fixed angle baffles may be more effective at some flow rates and less effective at others. As a way to compensate for varying flow rates, one modification of the system is to hinge the baffle plates 126 at their bases and move them with one or more actuators based on reactivation flow variation through the transition to optimize mixing angles under variable air flow. This system is shown in FIG. 5. Baffle section 222 includes one actuator 248 (248a-248c) for each baffle plate 126 (126a-126c). The actuators 248 can drive the baffle plates directly or through any suitable transmission system. The actuators 248 can be of rotational or linear drive. The actuators 248 can be controlled by a controller 250, which may be any suitable microprocessor utilizing one or more memories. The control can be based on a prestored look-up table (LUT) associating baffle inclination angles a with flow rates (reactivation fan speed) or can use dynamic feedback based on the temperature read by the reactivation temperature sensor or a reactivation air flow rate determined by a flow rate sensor (not shown). As the flow rate through the reactivation passage varies, controller 250 controls actuators 248 to move the baffle plates 126 to the optimal angle a. For example, angle a can range from 0° to 45°. Each baffle plate 126 need not necessarily be moved to the same angle. Testing can determine optimal combinations of angles for the various baffle plates. It should be noted that as the baffle plates are rotated in either direction, the amount of overlap of the distal ends of opposing, adjacent baffle plates 126 will vary. Baffle plates 126 of baffle section 222 should be designed such that there is at least some overlap between the distal ends of adjacent baffle plates 126 at every angle combination so as to prevent line-of- sight through the baffle section.

[0068] The foregoing baffle design is particularly effective in preventing temperature stratification when there is sufficient space in the reactivation ductwork between the heating source and the reactivation rotor inlet to accommodate two, or, preferably, three or more spaced baffle plates 126. The inventor has found that a linear distance of 50 cm or more is sufficient to accommodate the three-baffle system. Another embodiment of the baffle section is suitable for distances shorter than, for example, 50 cm between the heating source and the reactivation rotor inlet, namely, an array of helical baffles. The helical baffle system has been found to increase permeate flux by 50%. Permeate flux is defined as a volume flowing through a membrane per unit area per unit time. The flux has high dependency on temperature and pressure formed prior to exiting the helical baffle.

[0069] An example of a baffle section 322 formed of an array of helical baffle units 330 is shown in FIGs. 8-10. The shown embodiment includes a 5 X 5 array of helical baffle units 330, but the number and arrangement of baffles is not to be limited. In order to accommodate baffle section 322 in a rectangular or square ductwork, the helical baffle units 330 are mounted in a frame 335 by any suitable means. Frame 335 is formed to be solid so that air may pass through the baffle units 330 only through the openings 332 of the units. The frame 335 and helical baffle units 330 may be formed integrally, or can be formed of discrete components and subsequently assembled. The frame 335 and helical baffle units 330 may be formed of the same or different materials. For example, ceramic composites (such as 3D printed composites), composite carbon fiber, stainless steel grade metal, galvanized metal, and the like can be used. [0070] The openings 332 in each helical baffle unit 330 can be of any suitable size or shape that can create helical flow as air passes therethrough. The openings in FIG. 8 are in the form of parallel slots 332 in four adjacent quadrants, with the slots in each adjacent quadrant being rotated by 90° such that they would intersect if extended. The openings in FIGs. 9 and 10 are in the form of radial slots 332 of alternating lengths. It is important that the openings 332 include a baffle angle that can create helical movement of the air and prevent direct line-of- sight in an axial flow direction. That is, internal walls of the slots are not parallel to the z direction, but rather are angled relative thereto. Each inclined baffle angle will be between 25° and 45° as measured from the perpendicular plane facing the air stream. The arrays can be formed of a singular baffle unit 330 or plural baffle units 330 to account for the needed overall open cross- sectional size in order to maintain thermal mixing while reducing hydraulic burdens.

[0071] Although the focus of the embodiments in the foregoing description has been on minimizing thermal stratification at the reactivation inlet, the baffle sections 122, 222, 322 can also be considered for the process air outlet of a desiccant wheel, where moisture stratification has been known to exist. As shown in FIG. 7, in dehumidification unit 400, a baffle section 422 is positioned on the downstream side of the desiccant wheel 412 with respect to the process airflow direction (i.e., the -z direction). Baffle section 422 is of a similar design as baffle section 122 on the reactivation air side, and includes two, or, preferably, three or more baffles 426a- 426c. The shape of the ductwork can accommodate the shape of the process section 401 of the desiccant wheel 412. The size and shape of the process section 401 depends on what other sectors are provided on the wheel. Those of ordinary skill in the metalworking art would be able to design and construct suitable ductwork that both fits the size and shape of the process section

401, and transitions to the square or rectangular cross-sectional shape that houses baffle section 422. Of course, the present invention is not to be limited to a square or rectangular cross- sectional shape or any particular size, and many other sizes and shapes would be considered to be within the expertise of those of ordinary skill in the art. Baffle section 422 can achieve similar mixing results as those of baffle section 122 so as to sufficiently mix the process air flow to attenuate moisture stratification.

[0072] The inventor further found that stratification at the reactivation outlet can occur to at least a certain extent even with a thermally mixed rotor inlet condition. By inducing a dedicated and acceptable stratification condition to the rotor inlet, a uniform rotor outlet temperature profile condition can be achieved. The sweeping baffles described with reference to FIG. 5 can be used to balance airflow through the rotor so that cross-sectional velocities into the rotor will be uniform as well as thermally mixed and the rotor functionality will be maximized and/or effectively improved. Such will be particularly effective when the sweeping actuation of the baffle plates is tied to the sensed temperatures at the reactivation inlet, as described later.

[0073] The foregoing embodiments are effective in eliminating highly stratified air by utilizing a baffle system instead of a radiation screen between a heating element and the reactivation inlet to the rotor. In addition, utilizing a baffle system at the dehumidifier process outlet where stratified low moisture air is induced by the rotor outlet is also effective in minimizing moisture stratification. Preferably, when used in the regeneration airflow, the baffles are inclined toward the heat source at dedicated angles to increase thermal performance while preventing direct line- of-sight to the heating elements. Providing corrugated baffles can improve hydraulic performance, and providing actuated baffles can accommodate flow variation in the reactivation air while maintaining stratification attenuation at optimal baffle angles.

[0074] Accounting for stratification formation and attenuating such is important; however, a risk mitigation measure of determining a ground truth temperature value is desirable regardless of the mechanical attenuation of stratified air formation. As noted above, a single point temperature sensor has been utilized at the regeneration inlet side of the rotor, which may result in inaccurate temperature readings if the inlet air is stratified to any degree. The following embodiment utilizes a multi-element sensor application that can i) average the temperatures across the inlet opening of the regeneration sector, ii) determine whether any region in that sector has reached an upper temperature limit that would trigger an alarm, and iii) detect min/max anomalies in individual elements. Inputs from the multi-element sensor and from another temperature sensor downstream of the regeneration outlet are used in the known cascading PID loop control described with respect to FIG. 18. By acquiring a more accurate regeneration inlet temperature, available modulation of temperature of the regeneration heater, speed of the regeneration fan, speed of the purge fan, and/or speed of the rotor can be adjusted based on a true weighted average for more efficient air flow processing.

[0075] The present invention will allow for stratified air (formed, for example, by reactivation inlet sub-assemblies, i.e., radiation screens, or when reactivation flow conditions used in the baffle systems described above results in less than an acceptable degree of thermal mixing) to be measured as a ground truth temperature at the precipice of the rotor inlet. (In building physics and in remote sensing methods devoted to the identification of weighted average temperatures, the term "ground truth" is used for a verification made in the field to test the validity of a single reading deduction, and to correct the interpretation, if possible.) Controlling the unit heat-to temperature (temperature of air as it approaches the rotor inlet) based on a specific stratified layer measurement instead of a ground truth value (weighted average temperature) can lead to high energy use when the sensor portrays a lower temperature than that actually supplied (ground truth temperature representation) by the heating source, or adversely lower rotor efficiency due to sensor portrayal of higher temperature detection than that actually supplied by the heating source. Temperature profile misrepresentation due to stratification or an otherwise unacceptable degree of thermal mixing can cause high energy use or reduced wheel performance due to programmable logic controller (PLC) heater modulating to higher or lower kilowatt outputs, respectively.

[0076] Decoupling ground truth measurement from a mechanical root cause solution is not necessarily the preferred solution due to the following factors:

[0077] a. The end-use environment of dehumidifier systems will result in different heater setups and sizes. Multiple heater setups/sizes will require multiple mechanical mixing solutions. Testing all permutations of these solutions will result in a safety factor associated with defined boundary conditions.

[0078] b. The end-use environment of dehumidifier systems will also result in ducting to and from the reactivation sector on the unit, which can change the stratification profile on the face of the rotor and increase the potential of a point temperature process value misrepresentation. The following describes a system and process to account for a stratified airstream into the rotor to better represent the heat profile the rotor is experiencing from the heater section sub-assembly and post-processed at the rotor outlet. Accurate measuring (with anomaly detection) of the temperature to and from the rotor, respectively, will increase controllability of the reactivation cascading PTD loop, maintain the dehumidification unit at its intended performance, improve limit switch accuracy (reduce nuisance trips by maintenance personnel), and provide a method to auto-test the adherence of the read temperature to the sensing element ground truth level. The system and method involve positioning an averaging sensor of a plurality of sensing elements along key weighted average sectors at close proximity to the rotor facial regeneration inlet. Sensor elements connectivity will follow thermoelectric laws of plural resistance temperature detectors (RTDs) and thermocouple averaging. Reading the temperature sensor values will represent a ground truth value for input to the onboard PLC cascading PID (as TEi) and the safety limit switch (as TSi). Such an accurate reading can be used with the actuated baffle system described earlier in order to actively mitigate stratification at initial settings as well as when parameters change during operation. Also, the individual readings can be used to identify temperature stratification across the reactivation inlet, and the baffle motors can be actuated to adjust the baffles to eliminate the stratification. Such can be effected by a feedback loop or using pre-tested and stored parameters. The multi-element sensor array can be a direct replacement for existing sensors. Anomaly detection functionality is an additional feature, but the sensor array can have a standalone capability to connect to an A/D card (PLC expansion module) and/or a limit switch without system on a chip (SOC) output.

[0079] Regarding the anomaly detection methodology, one preferred example is median absolute deviation (MAD), which is a robust statistical measure (as opposed to standard deviation detection, which is not susceptible to outliers) of variability of a univariate sample set (such as the reactivation rotor inlet temperature profile). Other anomaly detection algorithms can be used as well, such as density-based spatial clustering of applications with noise (DBSCAN). While MAD and DBSCAN are available options for the anomaly detection methodology, such is not limiting and other known methodologies may be suitable. The plurality of sensing elements (e.g., multi-point thermocouples) have their lead wire extension measure temperatures at various points along a sheath encasing the plural sensing elements across a specified length (depending on reactivation inlet dimensions). The design can include smaller diameter thermocouples or l ' l RTD elements placed inside a single outer sheath. This construction will allow for a temperature profile to be represented at various points along a single line. The present invention is not limited to a single sheath sensor and can include a plurality of sheaths to be arrayed into one reactivation inlet cross-section.

[0080] The sheathed sensor array (RTD or thermocouple) follows any preferred sensor type methodology of measurement. RTD sensing elements will follow the curve-fitting Callendar- Van Dusen equation in order to measure the resistance of the sensing elements as current is supplied therethrough.

[0081] Thermocouples subjected to a change in obtaining temperature readings in environments will follow the Seebeck and Peltier effects, which will allow for current to flow between the two junctions of the thermocouple and to allow the thermocouple junction to either absorb or release heat, respectively. The Seebeck effect is when electricity is created between a thermocouple when the ends are subjected to a temperature difference between them. The Peltier effect occurs when a temperature difference is created between the junctions by applying a voltage difference across the terminals.

[0082] RTD connectivity will follow a parallel and series resistance connectivity (sensor element count dependent) to maintain a PT-1000 (or other) sensor inherent ohm value. A continuous element (averaging RTD) can also be used in the sheathed stainless steel enclosure as another embodiment. In such case, a plurality of these will be needed in order to account for the weight average losses along the sensed cross-section.

[0083] The thermocouple connectivity will maintain a parallel relationship to a common junction connectivity in order for their electromotive force to generate a mean of the temperature of the individual junctions (it being important to maintain the resistance of all the elements). [0084] Positioning of the sensing elements (aimed at the spatial representation of the temperature profile) along the sheathed sensor will follow the weighted averaging location along the rotor radius because the exposed rotor cross-sectional area increases further from the center. Therefore, a majority of the sensing elements will be located further from the rotor center and a minority will be located closer to the rotor center along the sheathed stainless steel tube. Selection of the sheathed sensor array positions can be defined by expert rules in order to avoid non-stratification related stagnant areas, which may not have representable temperatures.

[0085] An example sensor array 500 having four sensing elements 502a-502d along a sheathed enclosure 504 at various placements, starting at the sheath tip (PT.l) and incremented toward the sheath base (PT. 4), is shown in FIG. 12, and its location relative to the rotor reactivation inlet is shown in FIG. 13. Positioning of several sheathed sensor arrays per rotor inlet opening (with each sensor sheath having several sensing elements) will be dictated by the severity of stratification, with the preference to limit the applied sheathed sensor to one in conjunction with improved mechanical stratification attenuation features as discussed above. Providing full duplex functionality of the above-mentioned build methodology is important for the TEi and TSi functionality of the unit reactivation cascading loop and safety limit switch requirements. In that regal'd, at least at the tip of the sheath, duplex temperature sensors can be provided, one for TEi and one for TSi.

[0086] The sheath base 506 houses an edge termination block of the sensor wiring and SOC 508. The sensor array can be connected directly to an existing thermocouple or RTD module on the dehumidifier PLC or have a separate output. Either analog output (4-20 mA) representing the >%pct value or a DO alert of anomaly detection >%pct count can be used. The SOC 508 evaluates the MAD value (median of the absolute deviations from the data's median) in the following preferred manner, although such is not limiting. [1] An initial data set will be recorded along a specified length of time. [2] The deviation between each of the recorded temperatures (from each sensing element) to the overall median will be recorded. [3] The MAD value will be calculated as the median of the absolute values of all the deviations. [4] The MAD values calculated for all the points will be multiplied by a normalization constant (normalizing it to a comparable level of a normal distribution standard deviation). [5] The value in step [4] will be multiplied by a tolerance parameter (which will dictate how many deviations from the median a temperature measurement has to be in order to be considered an outlier). [6] Using a second parameter will distinguish if more than %pct in a time series of data set points are considered an outlier, and if so, the whole series will be flagged as an outlier.

[0087] As noted above, DBSCAN can alternatively be used as the anomaly detection methodology, especially due to synchronicity (temperature sensing elements should represent a synchronized, non-buffered representation ) expectation from the sensor array at quasi- stratified conditions.

[0088] Sensor anomaly detection can also employ deviation from linearity of the sensor reading (resistance measurement on the SOC adherence to the Callendar-Van Dusen equation for the RTD and millivolt measurements for the thermocouple array).

[0089] In testing an RTD array and a thermocouple sheath array (under stratified conditions) for linearity against a ground truth sensors array, the averaged RTD prevailed while outliers emerged as a recurring phenomenon when the thermocouple array was tested. The MAD algorithm is preferred when reading the sensor array.

[0090] Utilizing multiple element thermocouples and/or continuous RTDs for defining/representing a weighted average rotor inlet temperature profile increases the dehumidifier potential to have a lower carhon footprint by utilizing only the required energy (KW) for the reactivation process by improving the cascading loop functionality due to more accurate reading of the reactivation inlet temperature. The improved system will also result in fewer limit switch nuisance trips by maintenance personnel.

[0091] Adopting anomaly detection (MAD, DBSCAN, etc.) methodologies to diagnose ground truth value outliers based on a time series feed from the plurality of the sensor elements can enable alerting of a potential deviation from optimized rotor performance and detection of true limit switch threshold deviations. This can also distinguish sensing element drift and identify stratification formation due to commissioning and retro-commissioning processes on the dehumidifier equipment.

[0092] The present invention can be used in any dehumidification units that may present reactivation stratification phenomena, such as that which occurs at low airflow rates in large scale industrial unit rotor inlets. The system can also be used on suspected units without prior knowledge of reactivation stratification to eliminate concerns due to customer ducting and installation misuse.

[0093] The foregoing embodiments have been described with respect to dehumidifier units, but are not intended to be limited thereto. For example, the baffle systems described herein will also be effective in other sorption systems that absorb or adsorb other components in a fluid flow, such as noxious gases and CO2. Likewise, although this invention is intended to acquire more accurate readings of temperatures at the regeneration inlet side of a rotor, such as those used in large scale dehumidifiers, the described temperature sensing may be useful in any system that includes a heated regeneration airstream through a rotor, such as VOC scrubbers. [0094] Although the invention has been described with reference to specific embodiments, it will be understood by those skilled in the art that various changes may be made without departing from the spirit or scope of the invention. For instance, the numerous details set forth herein, for example, details relating to the configuration and operation of the described embodiments of the dehumidifier units, are provided to facilitate the understanding of the invention and are not provided to limit the scope of the invention. Accordingly, the disclosure of embodiments of the invention is intended to be illustrative of the scope of the invention and is not intended to be limiting.