Drift detection apparatus, system, and method

Abstract

In one aspect, the air contactor includes an air flow generator for generating an air flow, a liquid distribution system operable to distribute a liquid contacted by the air flow, and a sensor configured to detect an air variable of the air flow. The controller is configured to determine an operating variable of at least one of the air flow generator and the liquid distribution system. The controller is further configured to determine a drift state of the air contactor based at least in part on the air variable of the air flow and the operating variable of at least one of the air flow generator and the liquid distribution system.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS)

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 394,687, filed August 3, 2023, which is incorporated herein by reference in its entirety.

[0002]

[0002] The present disclosure relates to air contactors, and more particularly to monitoring drift in air contactors. [Background technology]

[0003]

[0003] Various types of air contactors are known, including heat exchanger systems such as direct and indirect heat exchanger systems. Some direct heat exchanger systems operate by dispersing a hot process liquid (e.g., water) on a fill sheet and directing ambient air over the liquid-covered fill sheet to remove heat from the process fluid. As the air passes through the liquid-covered fill sheet, the process fluid is cooled as heat is transferred from the liquid to the air.

[0004] Some indirect heat exchanger systems are considered wet indirect heat exchanger systems and include an indirect heat exchanger, such as a coil, pillow-type heat exchanger, plate heat exchanger, and / or fin-and-tube heat exchanger. A hot process fluid (e.g., water, steam, or coolant) moves through the passages of the indirect heat exchanger. The system distributes an evaporating liquid over the indirect heat exchanger and generates an airflow through the indirect heat exchanger covered with the evaporating liquid. The evaporating liquid indirectly absorbs heat from the process fluid to cool it. As the evaporating liquid moves along the exterior surface of the indirect heat exchanger, a portion of the evaporating liquid evaporates.

[0005] One drawback of some existing heat exchanger systems that distribute liquid (e.g., dispersing process liquid on a fill sheet or dispersing vaporized liquid on an indirect heat exchanger, as discussed above) is that the air flow through the heat exchanger carries some of the liquid particles away and carries them out of the heat exchanger. Liquid particles carried by the air flow, referred to herein as drift, can be undesirable due to the chemicals and bacteria within the liquid particles. For example, the liquid particles can rest on components on the exterior of the heat exchanger, resulting in corrosion and / or scale and mineral buildup. Some heat exchangers include drift eliminators to reduce the amount of drift that leaves the heat exchanger, but such drift eliminators often cannot remove all of the drift from the air flowing through the heat exchanger. Summary of the Invention

[0006] In one aspect of the present disclosure, an air contactor is provided that includes an air flow generator for generating an air flow, a liquid dispersion system operable to disperse a liquid contacted by the air flow, and a sensor configured to detect air variables of the air flow. The air variables may include, for example, relative humidity, temperature, and / or particulate matter of the air flow. The air contactor further includes a controller configured to determine an operating variable of at least one of the air flow generator and the liquid dispersion system. For example, the air flow generator may include a fan assembly, and the liquid dispersion system may include a pump. The controller may determine an air flow generator operating variable including a speed of the fan assembly and a liquid dispersion system operating variable including whether the pump is on or off. The controller is further configured to determine a drift state of the air contactor based at least in part on the air variable of the air flow and the operating variable of at least one of the air flow generator and the liquid dispersion system. In this manner, the controller can use air variables of the air flow within the air contactor and operational variables of at least one of the air flow generator and the liquid dispersion system to provide an accurate assessment of air contactor drift.

[0007]

[0007] The present disclosure also provides a method of operating an air contactor having an air flow generator that generates an air flow. The method includes operating a liquid distribution system of the air contactor to distribute a liquid in contact with the air flow. The method further includes detecting an air variable of the air flow with a sensor of the air contactor and determining an operating variable of at least one of the air flow generator and the liquid distribution system. The method includes determining a drift state of the air contactor based at least in part on the air variable of the air flow and the operating variable of the at least one of the air flow generator and the liquid distribution system. This facilitates the method determining the drift state using both the air variable of the air flow and the operating variable of the air contactor, rather than relying solely on air flow detection.

[0008] In one aspect, an apparatus for detecting drift in an air flow of an air contactor is provided. The air flow has a first velocity within the air contactor. The apparatus includes an inlet for receiving a portion of the air flow and an outlet. The apparatus further includes an air flow generator configured to cause the portion of the air flow to have a second velocity corresponding to the first velocity of the air flow of the air contactor. The sensor is operable to detect a variable of the portion of the air flow as the portion of the air flow travels at the second velocity. The corresponding air velocities inside and outside the apparatus promote similar flow rates of particulates and water vapor inside and outside the apparatus, so that detection of a variable of the air inside the apparatus is representative of detection of the air outside the apparatus.

[0009] Also provided is a method for detecting drift in an air contactor airflow. The method includes determining a variable representative of a first velocity of the airflow in the air contactor. The method further includes controlling the drift detection device so that a portion of the airflow entering the drift detection device at the first velocity travels through a passageway of the drift detection device at a second velocity corresponding to the first velocity. The method includes detecting a variable of the portion of the airflow with a sensor as the portion of the airflow travels through the passageway at the second velocity. Because the air velocities inside and outside the drift detection device correspond, detecting a variable of the portion of the airflow within the drift detection device can represent a variable of the airflow outside the drift detection device. [Brief explanation of the drawings]

[0010] [Figure 1A]

[0010] A schematic diagram of a direct heat exchanger system including drift measurement sensors at the air outlet and air inlet of the heat exchanger system. [Figure 1B]

[0011] FIG. 1B is an exemplary block diagram of the cooling tower of FIG. 1A. [Figure 2]

[0012] 1B is an exemplary graph illustrating relationships between monitored variables of the heat exchanger system of FIG. 1A. [Figures 3A-3F]

[0013] 1B is an exemplary chart showing how the changing conditions of the heat exchanger system of FIG. 1A are used to detect changes in drift. [Figure 4]

[0014] FIG. 1B is a schematic diagram of the drift measurement sensor of FIG. 1A according to one embodiment. [Figure 5-35]

[0015] 1B is a schematic diagram of the drift measurement sensor of FIG. 1A according to another embodiment. [Figure 36A]

[0016] 1 is a schematic diagram of a heat exchanger having an indirect heat exchanger and drift measurement sensors at the air outlet and air inlet of the heat exchanger; FIG. [Figure 36B]

[0017] 36B is a schematic diagram of an alternative configuration of the heat exchanger of FIG. 36A, the heat exchanger of FIG. 36B having a drift measurement sensor between the indirect heat exchanger and the fan of the heat exchanger. [Figure 37A]

[0018] 1 is a schematic diagram of a heat exchanger apparatus having an indirect heat exchanger adiabatic precooler upstream of the indirect heat exchanger, the heat exchanger apparatus including drift measurement sensors at an air outlet and an air inlet of the heat exchanger apparatus. [Figure 37B]

[0019] 37B is a schematic diagram of an alternative configuration of the heat exchanger of FIG. 37A, the heat exchanger of FIG. 37B having a drift measurement sensor between the adiabatic precooler and the indirect heat exchanger of the heat exchanger. [Figure 38-53]

[0020] FIG. 10 is a schematic diagram of a drift measurement sensor according to another embodiment. [Figure 54-55]

[0021] 1B is a schematic diagram of the drift measurement sensor of FIG. 1A according to another embodiment. [Figures 56A-56E]

[0022] 1B is an exemplary chart showing how the changing conditions of the heat exchanger system of FIG. 1A are used to detect changes in drift. DETAILED DESCRIPTION OF THE INVENTION

[0011]

[0023] In one aspect of the present disclosure, a drift measurement sensor is disclosed that can be used to monitor the condition of an air contactor and determine the drift rate and / or drift rate change of the air contactor. The air contactor contacts a process fluid, such as a liquid or a liquid / gas mixture (e.g., water and steam), with air. The air contactor can, for example, transfer heat and / or mass between the fluid and the air. Examples of air contactors include air pollutant capture systems, packed absorber towers, rotary dryer systems, and heat exchange devices such as cooling towers 100. The drift measurement sensor can be mounted at the air inlet and / or air outlet of the cooling tower and can include one or more sensors to monitor air variables of the air flowing into and out of the cooling tower. The air variables can include variables representing the air itself, such as dry bulb, wet bulb, and / or air pressure, as well as variables representing particles carried by the air. The airborne particles can include, for example, liquid water, aqueous solutions, and / or other liquids, such as CO2 capture solutions. In one embodiment, the drift (e.g., liquid water droplets) can be condensed and pooled, and the one or more sensors include sensors for detecting liquid variables, such as the conductivity, pH, alkalinity, free chlorine, oxidation-reduction potential (ORP), and / or microorganisms of the pooled water. As another example, the air variable can include a particulate matter sensor configured to detect the rate of accumulation of particles of various sizes, such as salts and other minerals dissolved in the drift liquid water droplets. The cooling tower 100 can include a controller 162 configured to monitor cooling tower operating variables, such as the speed of the cooling tower fan assembly, whether the cooling tower's liquid distribution system is dispersing liquid, and / or variables of the liquid being dispersed by the liquid distribution system. The controller 162 can be configured to determine a drift condition, such as an unacceptable change in drift rate, based on changes in the air variable and the cooling tower's 100 operating variables.

[0012]

[0024] The drift measurement sensors described herein can be used in various air contactors to determine drift conditions. For example, one or more of the drift measurement sensors disclosed herein can be used with an air pollutant capture device that removes pollutants from the air. For example, the air pollutant capture device can utilize a capture medium, such as a liquid capture solution (e.g., a CO2 capture solution), and a support (e.g., a fill sheet). The liquid capture solution can include, for example, an aqueous solution of hydroxide or potassium hydroxide. The liquid capture solution can be sprayed onto the fill sheet, and the CO2 capture solution travels along the fill sheet, carrying CO2 from the air into the liquid, which is collected in the sump of the air pollutant capture device. In some situations, spraying the CO2 capture solution onto the fill creates a drift of the CO2 capture solution within the air pollutant capture device. A controller associated with the air pollutant capture device can use air variables (e.g., the pH of the CO2 capture solution drift) and operating variables of the air pollutant capture device to determine whether the detected drift change is unacceptable and adjust the operation of the air pollutant capture device to address the drift condition.

[0013]

[0025] Referring to FIG. 1A , a heat exchange device, such as a cooling tower 100, is provided. The cooling tower 100 monitors changes in drift. While a cooling tower is provided as an example herein, the concepts disclosed in the following discussion may similarly be used in a variety of applications, such as other heat exchanger systems, including swamp coolers, building humidification systems, and air handlers, as well as heat exchanger systems for hospitals, greenhouses, and / or livestock. The heat exchanger system may utilize a direct heat exchanger, a wet indirect heat exchanger, and / or adiabatic cooling. Furthermore, while a cooling tower 100 having a direct heat exchanger is provided as an example, the concepts disclosed in the following discussion may similarly be used in other heat exchanger systems that discharge a liquid, such as an indirect heat exchanger. The cooling tower 100 includes an airflow generator, such as a fan assembly 102, a heat exchanger 103, such as a direct heat exchanger including a fill 104, and a liquid distribution system 106 for distributing a process fluid over the fill 104.

[0014]

[0026] The fan assembly 102 includes a fan 110 and a motor 112 that rotates the fan to generate airflow along a path 114 relative to a housing 115 of the cooling tower 100. Specifically, the fan assembly 102 draws air into an air inlet 118 of the housing 115 and delivers it through the exterior surface of the filter 104 to an outlet 130. The air inlet 118 may include a filter 120 mounted within an opening in the inlet 118 that filters debris from the air upstream of the filter 104. Alternatively or additionally, the air inlet 118 may include a damper, such as a louver, that prevents liquid from splashing or exiting the cooling tower 100 through the air inlet 118. The louvers may also prevent ultraviolet light from directly contacting the water, for example, to inhibit algae growth. The fan assembly 102 includes one or more sensors for monitoring the operation of the motor 112, such as a motor speed sensor 102A and a motor power sensor 102B.

[0015]

[0027] After flowing through the fill 104, the air flows through the drift eliminator 122. The drift eliminator 122 provides a serpentine path for the airflow, and as the air travels through the drift eliminator 122, water in the air strikes and collects on the surfaces of the drift eliminator 122. For example, the drift eliminator 122 can include blades or baffles through which the air and drift matter flow from the fill 104 toward the outlet 130. The baffles create curved and / or angled channels that change the direction of the air flowing through the drift eliminator 122, allowing the drift matter in the air to strike the baffles and collect within the drift eliminator 122. For example, when the drift matter strikes the baffles, it loses velocity and collects on the inner surface of the drift eliminator 122. The water collected by the drift eliminator 122 moves downward under the influence of gravity into the sump 132.

[0016]

[0028] Although drift eliminators reduce drift in the air, conventional drift eliminators cannot remove all drift from the air, and some drift can pass through. Specifically, small particle size drift (e.g., less than 10 micrometers) can often flow through conventional drift eliminators. Such small particle size drift can be carried significant distances in the air and, as discussed above, may contain chemicals and / or bacteria. It may be desirable to limit drift downstream of drift eliminator 122 within cooling tower 100, as well as limit drift being emitted from cooling tower 100.

[0017]

[0029] The liquid distribution system 106 includes a conduit 124 through which a process fluid flows to the cooling tower 100. The process fluid may include, for example, water and / or glycol (e.g., propylene, ethylene). The process fluid may be a fluid heated by a chiller system and transported to the cooling tower 100 for cooling. The liquid distribution system 106 includes a pump 126 operable to inject the process fluid into the cooling tower 100 via the conduit 124. The pump 126 may be operated in response to a control signal from a controller 162. For example, the pump 126 may receive a control signal to operate at a particular speed. A speed sensor 127 may monitor a speed variable of the pump 126, such as pump RPM. The speed sensor 127 may collect and transmit speed data to the controller 162. A power sensor 128 may monitor a power variable related to the power consumed by the pump 126, such as kW. The power sensor 128 may collect and transmit power data to the controller 162. The liquid distribution system 106 may include a temperature sensor 146 for detecting a temperature variable, such as degrees Fahrenheit (°F), of the process fluid in the conduit 124 flowing into the cooling tower 100. The liquid distribution system 106 may include a flow meter 148 for detecting a flow variable, such as gallons per minute, of the process fluid flowing into the cooling tower 100 via the conduit 124. The controller 162 may receive data from the temperature sensor 146 and / or the flow meter 148.

[0018]

[0030] The liquid distribution system 106 includes one or more openings, such as nozzles 129, through which the process fluid is injected and dispersed onto the fill 104. The nozzles 129 are fluidly coupled to the conduits 124, so that the process fluid injected through the conduits 124 can be injected through the nozzles 129. The nozzles 129 spray the process fluid onto the fill 104, where it flows through the fill 104 and into the sump 132. The fill 104 may include cubes and / or sheets, as some examples. In one embodiment, the fill 104 includes a sheet, and the process fluid travels downward under the influence of gravity along ridges, valleys, etc., on the outer surface of the fill sheet. In another embodiment, the liquid distribution system includes one or more grooves with openings, allowing the liquid to fall down the grooves and into the fill.

[0019]

[0031] As the process fluid flows through the fill 104 and into the sump 132, it is cooled by the airflow generated by the fan assembly 102. The rotation of the fan 110 moves air from the air inlet 118 of the cooling tower 100, through the fill 104, upward through the fan assembly 102, and out through the air outlet 130. In one approach, the process fluid flowing through the fill 104 has a higher temperature than the air flowing through the fill 104, so heat is transferred from the higher temperature process fluid to the cooler airflow moving through the fill 104.

[0020]

[0032] The cooled process fluid is collected in sump 132 and exits cooling tower 100 through outlet 133. For example, pump 135 may pump the cooled process fluid to a chiller system. Cooling tower 100 may include a fill level sensor 136, such as a float, that provides a signal indicative of the volume of liquid in the sump. Cooling tower 100 may include a temperature sensor 158 and a conductivity sensor 160 in sump 132 to monitor the temperature and conductivity of the fluid in sump 132. Controller 162 may receive data from temperature sensor 158 and / or conductivity sensor 160. Cooling tower 100 may additionally or alternatively include sensors to measure other variables of the fluid in sump 132, such as pH, alkalinity, free chlorine, oxidation-reduction potential (ORP), and / or microorganisms of the fluid in sump 132. Sump 132 may have a drain valve 138 that can be opened to drain fluid from sump 132 and out of circulation within cooling tower 100. For example, if the conductivity and / or pH of the process fluid exceeds one or more thresholds, drain valve 138 may be opened to drain fluid from sump 132, eg, as part of a liquid switching process.

[0021]

[0033] Cooling tower 100 may include one or more drift measurement sensors 150 to monitor one or more variables in cooling tower 100, such as variables related to air quality conditions. As shown in FIG. 1A , cooling tower 100 may include drift measurement sensors 150 at one or both of air outlet 130 and air inlet 118 of cooling tower 100. As discussed in more detail below, drift measurement sensors 150 may include sensors for monitoring variables indicative of drift.

[0022]

[0034] In one embodiment, one or more of the drift measurement sensors 150 include a temperature sensor 152, a relative humidity sensor 154, and a particulate matter sensor 156. The temperature sensor 152 can detect the dry-bulb temperature of the air. The particulate matter sensor 156 can operate to detect the amount of particles in the air, such as airborne water particles and / or airborne liquid droplets. The particulate matter sensor 156 can provide a particulate rate (e.g., particles per minute or hour). The particulate matter sensor 156 can detect dust, soot, smoke, and other chemicals or pollutants in the air, such as those emitted by power plants, industries, and / or automobiles. Some particulate matter sensors 156 can include a membrane configured to allow particles of a specific size to pass through. The particulate matter sensor 156 can operate to detect particles passing through the membrane to measure the amount of particles in the air and drift. Some particulate matter sensors 156 can detect the concentration of particles in the air using light scattering techniques, for example, by passing a light beam through an air sample and detecting the scattering of the light beam by particles in the air sample. The particulate matter sensor 156 may include multiple sensors for detecting particles of different size ranges, such as a PM2.5 sensor for detecting particles less than 2.5 micrometers in width and a PM10 sensor for detecting particles less than 10 micrometers in width. Other particulate matter sensors may additionally or alternatively be used to measure particulates of other sizes, such as a PM1 sensor for detecting particles less than 1 micrometer in width.

[0023]

[0035] 1B , cooling tower 100 is associated with a controller 162 that controls operation of cooling tower 100, including fan assembly 102 and liquid distribution system 106. Controller 162 can be integrated with cooling tower 100 or remote from cooling tower 100. Controller 162 includes a processor 164, memory 166, and communication circuitry 168. Processor 164 communicates with memory 166 to provide functionality for cooling tower 100. Processor 164 can be configured to provide information processing functionality and can include multiple processing units in communication with each other. Processor 164 can include, by way of example, a digital processor, an analog processor, a PID controller, a microprocessor, a microcontroller, an application-specific integrated circuit (ASIC), and / or a system-on-chip. Memory 166 can store logic, instructions, and operating variables accessible by processor 164 to operate cooling tower 100. The memory 166 may include, for example, RAM, DRAM, SDRAM, EEPROM, ROM, flash memory, and / or a hard drive. The communications circuitry 168 may include, for example, wired and / or wireless interfaces. Examples include an Ethernet interface, a Wi-Fi network interface, and / or a Bluetooth interface. The processor 164 receives data from sensors in the cooling tower 100 to monitor the operation of the cooling tower 100. For example, the processor 164 may receive data from the drift measurement sensor 150, the inlet process fluid temperature sensor 146, the flow rate sensor 148, the pump speed sensor 127, the pump power sensor 128, the sump fluid temperature sensor 158, the sump particulate conductivity sensor 160, and other sensors in the cooling tower 100. The processor 164 may receive control signals and exchange data with a remote computer, such as an HVAC system controller, via the communications circuitry 168. As another example, the processor 164 may communicate with a remote device, such as a server computer and / or a technician's portable electronic device, such as a smartphone, tablet computer, or laptop computer.

[0024]

[0036] The processor 164 may receive a control signal including a setpoint temperature of the process fluid, such as the temperature of the process fluid exiting the cooling tower 100 via the outlet 133. The processor 164 may determine operating variables of the cooling tower 100 to achieve the setpoint temperature. For example, the processor 164 may control the speed of the inlet pump 126 and / or the fan assembly 102. The processor 164 may communicate control signals to the fan assembly 102 and / or the liquid distribution system 106 to achieve the setpoint temperature. The processor 164 may communicate control signals to the fan assembly 102 and / or the liquid distribution system 106 via the communications circuitry 168. The controller 162 may be connected to multiple cooling towers 100 and may be configured to operate each cooling tower 100 to meet the cooling demands of an associated building, for example. The communications circuitry 168 may be configured to communicate via wired and / or wireless communications protocols, such as Ethernet, Wi-Fi, Bluetooth, cellular, etc.

[0025]

[0037] The controller 162 operates the fan assembly 102 to generate airflow through the cooling tower 100. The controller 162 can operate the fan assembly 102 to draw air through the fill 104 and cool the fluid flowing through the fill. The controller 162 can also operate the liquid distribution system 106 to control the distribution of the process fluid over the fill 104. For example, the controller 162 can adjust the speed of the inlet pump 126 to increase or decrease the flow rate of the process fluid through the conduit 124.

[0026]

[0038] Operating the fan assembly 102 and / or inlet pump 126 at higher or lower speeds can increase drift in the air downstream of the drift eliminator 122. As discussed above, the drift eliminator 122 often cannot remove all of the drift from the air, which may then flow back into the fan assembly 102 and even out of the cooling tower 100. Drift eliminators are typically most effective in the middle of a specified air velocity range, but are less effective at air velocities lower and higher than the middle of the specified air velocity range.

[0027]

[0039] Drift from cooling towers is often undesirable due to, for example, the corrosion the drift causes, the mineral deposits left behind by the drift, and the appearance of the drift emanating from cooling tower 100. Controller 162 can detect drift in cooling tower 100 by monitoring variables in cooling tower 100. In one embodiment, controller 162 detects and responds to changes in drift based on changes in variables in cooling tower 100 collected by sensors in cooling tower 100. For example, if controller 162 determines that drift downstream of drift eliminator 122 is increasing, controller 162 can adjust operation of cooling tower 100 to reduce the drift and / or alert a user of the increased drift, such as by sending an SMS message or email.

[0028]

[0040] 2, an exemplary graph 200 is provided illustrating the relationship between variables monitored by cooling tower 100 and that may be used to determine changes in the cooling tower's 100 drift rate. Controller 162 may receive data from drift measurement sensors 150 mounted at air inlet 118 and air outlet 130 of cooling tower 100. Line 202 indicates the amount of particulate matter having a particle size less than 2.5 micrometers detected by particulate matter sensor 156 of drift measurement sensor 150 at air inlet 118 of cooling tower 100 over time. Line 204 indicates the amount of particulate matter having a particle size less than 10 micrometers detected by particulate matter sensor 156 of drift measurement sensor 150 at air inlet 118 of cooling tower 100 over time. Line 206 indicates the speed of fan assembly 102 over time when controller 162 operates fan assembly 102 to cool process fluid flowing through fill 104. Line 208 indicates the conductivity of the process fluid 134 (see FIG. 1A ) in the sump 132 over time. The controller 162 can detect the conductivity of the liquid using the conductivity sensor 160 in the sump 132. As the process fluid recirculates through the cooling tower 100, some of the water in the process fluid evaporates, increasing the concentration of salts and other particulates in the water and potentially increasing the conductivity of the liquid. Line 210 indicates the amount of particulate matter having a particle size less than 2.5 micrometers detected by the particulate matter sensor 156 of the drift measurement sensor 150 at the air outlet 130 of the cooling tower 100 over time. Line 212 indicates the amount of particulate matter having a particle size less than 10 micrometers detected by the particulate matter sensor 156 at the air outlet 130 of the cooling tower 100 over time. Controller 162 can monitor changes in the particulate matter at outlet 130 to determine whether the drift rate of cooling tower 100 is increasing or whether the amount of particulate matter at air outlet 130 can be attributed to other factors discussed in more detail with reference to Figures 3A-3F. As shown, as the conductivity of the fluid increases (as shown by line 208), the amount of particulate matter detected at air outlet 130 of cooling tower 100 increases, which may indicate an increase in cooling tower 100 drift rate.

[0029]

[0041] 3A-3F, exemplary charts are provided illustrating how changing conditions of the cooling tower 100 can be used to detect changes in the drift rate of the cooling tower 100. In these examples, the controller 162 monitors cooling tower variables, including cooling tower operating variables, such as the speed of the fan assembly 102, whether the liquid distribution system 106 is dispersing liquid, and the conductivity of the liquid dispersed by the liquid distribution system 106. The cooling tower operating variables also include air variables, such as particulate matter (PM2.5 and PM10) at the air inlet 118 and air outlet 130 of the cooling tower 100, and the relative humidity and temperature of the air at the air inlet 118 and air outlet 130 of the cooling tower 100. These conditions are provided by way of example, and fewer or additional variables may be monitored and / or used to assess a drift condition. For example, the controller 162 may monitor the flow rate of the liquid distribution system 106. Based on the monitored variables, changes in the drift rate of the cooling tower 100 may be detected. For example, a change in the amount of particulate matter at the air outlet 130 can be evaluated to determine whether the change is due to a change in drift rate or another changing condition of the cooling tower 100. In some embodiments, the controller 162 can be programmed to evaluate the changing condition of the cooling tower 100 to determine whether the drift rate of the cooling tower 100 is changing by a normal or abnormal amount, based on examples discussed below with reference to FIGS. 3A-3F. If the controller 162 determines that the change in drift rate is abnormal or unacceptable, the controller 162 can be programmed to modify the operation of the cooling tower 100 to reduce the drift rate, such as changing the cooling tower 100 from a wet mode to a dry mode, reducing fan speed, and / or notifying maintenance personnel. The fan speed is provided as a decimal representing a percentage. For example, 0.80 indicates that the fan assembly is operating at 80% of the maximum fan speed.

[0030]

[0042] 3A, an exemplary chart 300 is provided in which the cooling tower 100 condition changes from a baseline condition ("Baseline 1") to New State A or New State B. Changing from Baseline 1 to New State A causes the liquid conductivity 302 of the liquid dispersion system 106 to increase from 1250 μS / cm to 1550 μS / cm. Similarly, the amount of particulate matter 304 of PM2.5 and PM10 at the air outlet 130 increases from 25 μg / cm to 25 μg / cm, respectively. 3 and 30 μg / cm 3 to 28 μg / cm 3 and 34 μg / cm 3 The increase in particulate matter in the air outlet 130 may be due to an increase in the conductivity of the liquid in the liquid dispersion system 106. For example, an increase in the concentration of particles in the process fluid of the liquid dispersion system 106, as indicated by the increase in conductivity 302, may have increased the amount of particles in the drift droplets entrained from the fill 104. However, the increase in the amount of droplets entrained in the air stream is within a predetermined range of the expected increase in the amount of droplets entrained in the air stream and may be due, for example, to an increase in the surface tension of water resulting from an increase in the particle concentration in the process fluid. Thus, the system controller determines that there has been an expected or normal change in the drift rate of the cooling tower 100.

[0031]

[0043] When changing from baseline 1 to new condition B, the amount of particulate matter 308 of PM2.5 and PM10 detected at the air outlet 130 of the cooling tower 100 increased to 25 μg / cm 3 and 30 μg / cm 3 to 35 μg / cm 3 and 42 μg / cm 3While other monitored conditions remain the same, controller 162 determines that the drift rate of cooling tower 100 has increased abnormally because other variables of cooling tower 100 that could cause an increase in the amount of particulate matter at air outlet 130 have not changed and the change in the amount of particulate matter is outside a predetermined range of expected changes in particulate matter. For example, controller 162 may determine that the increase in particulate matter is due to an increase in the drift rate of cooling tower 100 rather than being the result of a change in another monitored variable of cooling tower 100.

[0032]

[0044] 3B, an exemplary chart 310 is provided illustrating an evaluation of a change in the speed of the fan assembly 102 against a drift rate determination. Changing from Baseline 2 to New Condition C, the speed 311 of the fan assembly 102 increases by 20%, and the amount of particulate matter 312 of PM2.5 and PM10 at the air outlet 130 increases by 17 μg / cm3, respectively. 3 to 27 μg / cm 3 , and 19 μg / cm 3 to 32 μg / cm 3 Although an increase in PM2.5 and PM10 particulate matter may result from an increase in the speed of the fan assembly 102, the drift rate of the cooling tower 100 does not increase significantly or above the drift rate expected for these operating conditions of the cooling tower 100. For example, an increase in the speed of the fan assembly 102 may move a larger volume of air toward the PM2.5 and PM10 sensors, resulting in higher PM2.5 and PM10 readings.

[0033]

[0045] Changing from baseline 2 to new state D increases fan assembly 102 speed 314 by 5%, and the detected amount of PM2.5 and PM10 particulate matter 315 more than doubles. Considering this increase in fan assembly 102 speed, the increase in PM2.5 and PM10 particulate matter is greater than, for example, the increase in fan speed and increase in particulate matter when changing from the same baseline 2 to new state C. Because the increase in particulate matter in air outlet 130 cannot be entirely attributable to the increase in fan assembly 102 speed or any other monitored condition, it can be determined that the drift rate of cooling tower 100 has increased. In other words, while some of the increase in the PM2.5 and PM10 particulate matter values may be attributable to the increased speed of the fan assembly 102, as in New State C, if the magnitude of the increase in the PM2.5 and PM10 particulate matter values is disproportionately greater than the increased speed of the fan assembly 102 in New State D, it may be determined that the drift rate has increased abnormally, for example, above an acceptable or expected drift rate for these operating states of the cooling tower 100. Although particulate matter increases when changing from Baseline 2 to New State C and New State D, only the increase in particulate matter from Baseline 2 to New State D is considered abnormal and triggers a determination of an unacceptable or abnormal drift increase.

[0034]

[0046] 3C, an exemplary chart 320 is provided illustrating an evaluation of the amount of particulate matter at the air inlet 118 of the cooling tower 100 as it changes while other monitored variables remain the same. Changing from the baseline condition of Baseline 3 to New States E and F increases the amounts of PM2.5 and PM10 particulate matter 321, 322 at the air inlet 118 by the same amount. However, changing to New State F increases the amount of PM2.5 and PM10 particulate matter 323 at the air outlet 130 by a greater amount than the increase in the amount of PM2.5 and PM10 particulate matter 324 when moving from Baseline 3 to New State E. It can be determined that in New State E, the increase in PM2.5 and PM10 particulate matter 324 at the air outlet 130 is due to an increase in particulate matter entering the cooling tower 100 at the air inlet 118, and therefore, there was no significant increase in drift rate. Under new condition F, the particulate matter 323 at air outlet 130 has increased significantly and / or disproportionately relative to the increase in particulate matter at air inlet 118 (e.g., compared to the change from the baseline condition of Baseline 3 to new condition E). As a result, it can be determined that the drift rate of cooling tower 100 has abnormally increased beyond an acceptable or expected drift rate under these conditions.

[0035]

[0047] 3D , an exemplary chart 330 is provided illustrating an evaluation of the change in fan assembly 102 speed and liquid dispersion system 106 liquid conductivity. Changing from the baseline condition of Baseline 4 to new conditions G and H, fan assembly speeds 331, 332 decrease by 15% and water conductivities 333, 334 increase. However, in new condition H, the amount of PM2.5 and PM10 particulate matter 336 at the air outlet 130 of the cooling tower 100 is greater than the amount of particulate matter 335 at new condition G. In new condition G, there was no significant increase in drift rate because the increase in PM2.5 and PM10 particulate matter 335 at the air outlet 130 can be attributed to the increase in liquid dispersion system 106 liquid conductivity despite the decrease in fan assembly 102 speed 331. In new condition H, the amount of particulate matter 336 in the air outlet 130 has increased significantly and / or disproportionately (e.g., compared to the change in new condition G) relative to the increase in liquid conductivity 334 of the liquid distribution system 106 and the speed reduction 332 of the fan assembly 102. The controller 162 determines that the increase in particulate matter 336 in the air outlet 130 is the result of an abnormal increase in the drift rate of the cooling tower 100 beyond an acceptable or expected drift rate for these conditions, because not all of the increase in particulate matter 335 can be attributed to the increase in liquid conductivity 334 or any other monitored condition.

[0036]

[0048] 3E and 36A, an exemplary chart 340 is provided for a heat exchanger using an indirect heat exchanger, such as heat exchanger apparatus 700. Chart 340 illustrates an evaluation of the speed change of fan assembly 702 when liquid distribution system 706 begins distributing fluid over an indirect heat exchanger, such as pillow plate heat exchanger 717. Turning on liquid distribution system 706 to spray water over pillow plate heat exchanger 717 can assist in cooling the process fluid, for example, in addition to the cool air sent over pillow plate heat exchanger 717 by fan assembly 702. Changing from baseline state Baseline 5 to new states I and J, fan assembly 702 speeds 341 and 342 are reduced by 35% and liquid distribution system 706 is turned on (343 and 344). The amount of PM2.5 and PM10 particulate matter 345 at air outlet 713 of heat exchanger apparatus 700 in new state J is greater than the particulate matter 346 in new state I. For the transition to new state I, even though the speed of the fan assembly 702 was reduced, the increase in PM2.5 and PM10 particulate matter in the air outlet 713 can be attributed to the liquid dispersion system 706 now spraying or dispersing liquid and does not indicate a significant increase in drift rate. For the transition to new state J, the particulate matter 345 in the air outlet 713 increased significantly more than could be attributed solely to spraying liquid via the liquid dispersion system 706. Because the increase in particulate matter 345 in the air outlet 713 cannot be entirely attributed to the monitored conditions, it is determined that the drift rate of the heat exchange device 700 has increased beyond acceptable or expected drift for these operating states of the heat exchange device 700.

[0037]

[0049] 3F, an exemplary chart 350 is provided illustrating an evaluation of the change in particulate matter at the air outlet 713 of the heat exchanger 700 to determine if there has been a change in drift rate. Changing from baseline state BASELINE 6 to new state K, the speed 351 of the fan assembly 702 is reduced, the liquid dispersion system 706 remains off 352 (e.g., not spraying liquid), and particulate matter 353 at the air inlet 711 increases, while particulate matter 354 at the air outlet 713 increases. Changing to new state K shows that there was no increase in drift rate because there can be no significant drift when the liquid dispersion system 706 is off and not dispersing liquid. With the liquid dispersion system 706 off, there are no droplets sprayed by the liquid dispersion system 706 to be swept away in the air flowing from the air inlet 711 to the outlet 713. Therefore, the increase in particulate matter at the air outlet 713 can be attributed to an increase in particulate matter entering the heat exchanger at the air inlet 711.

[0038]

[0050] Changing from baseline 6 to new state L, the speed 355 of the fan assembly 702 decreases, the liquid distribution system 706 is turned on (356), the liquid distribution system liquid conductivity 357 decreases, the particulate matter 358 at the air inlet 711 increases, and the particulate matter 359 at the air outlet 713 increases. While the fan speed and liquid conductivity have decreased, the particulate matter at the air outlet 713 has increased significantly. This significant increase in particulate matter at the air outlet 130 cannot be entirely due to the increase in particulate matter at the air inlet 711 and the liquid distribution system 706 being turned on. Therefore, the controller 162 can determine that the drift rate of the heat exchange device 700 has increased beyond an acceptable or expected drift rate under these conditions.

[0039]

[0051] In some embodiments, a controller 162 of a heat exchange device, such as a cooling tower 100 or a heat exchange device 700, monitors changes in the condition of the heat exchange device to determine whether the drift rate has increased. To determine whether the drift rate of the heat exchange device has changed (e.g., increased), the controller 162 can compare the change in the condition of the heat exchange device to data sets known to correspond to changes in drift conditions or data sets known not to correspond to significant changes in drift conditions, such as the data sets provided in the charts of Figures 3A-3F. In some embodiments, the controller 162 processes the monitored variables using machine learning algorithms to determine, for example, whether an increase in particulate matter at the air outlet of the heat exchange device can be attributed to a change in the condition of the heat exchange device or is the result of an increased drift rate of the heat exchange device.

[0040]

[0052] If the controller 162 determines that the drift rate of the heat exchanger device has increased, the controller 162 can send a warning indicating that the drift rate of the heat exchanger device has increased. The controller 162 can then alert the operator of the heat exchanger device, allowing the operator to, for example, measure the amount of drift through other techniques to determine whether drift exists and / or determine whether the drift is an acceptable amount, determine whether to adjust the operation of the heat exchanger device, and / or investigate why the drift rate is increasing. The controller 162 can enter a fail-safe operating mode and operate the heat exchanger device to mitigate the drift, for example, by operating in a dry mode or reducing the flow rate of evaporative liquid sprayed onto the indirect heat exchanger of the heat exchanger device. In some forms, the controller 162 can notify the controller of the building's HVAC system that the drift rate of the heat exchanger device is increasing, allowing the HVAC system to adjust the operation of the HVAC system to reduce the drift of the heat exchanger device.

[0041]

[0053] While the above example describes controller 162 determining whether a drift rate is acceptable based on a changing cooling tower variable, controller 162 can also determine whether a cooling tower's drift rate is acceptable based on the cooling tower's current variables, for example, without evaluating the change in drift rate relative to the changing cooling tower variable. In other words, controller 162 can evaluate whether a cooling tower's drift rate is acceptable at a given time when operating with specific cooling tower operating variables, given the air quality conditions in which the cooling tower is operating. Controller 162 can determine whether a drift rate is normal or abnormal, for example, by comparing the cooling tower variables to a data set of cooling tower variables known to correspond to normal or abnormal drift conditions. As another example, controller 162 can use a machine learning algorithm to evaluate whether a cooling tower's drift rate is acceptable given current cooling tower operating variables and air variables.

[0042]

[0054] Referring to FIG. 4 , a drift measurement sensor 150 is shown according to one embodiment. The drift measurement sensor 150 includes a conduit, such as a tube 170, which defines a passageway 172 through which air can flow through the drift measurement sensor 150. The tube 170 may have sidewalls that extend around the passageway 172. The drift measurement sensor 150 includes an inlet 174 through which air can enter the passageway 172 and an outlet 176 through which air can exit the passageway 172. The drift measurement sensor 150 includes one or more sensors mounted on the conduit 170 for measuring the condition of the air flowing through the passageway 172 of the drift measurement sensor 150. The drift measurement sensor 150 may include a temperature sensor 152, a relative humidity sensor 154, and a particulate matter sensor 156 (e.g., one or more sensors for measuring PM2.5 and PM10). The sensors may be mounted closer to the outlet 176 of the drift measurement sensor 150 than the inlet 174, which may help, for example, to ensure that the airflow through the drift measurement sensor 150 is substantially uniform. The sensors may be mounted within the passageway 172 such that the sensors minimize obstruction of the flow of air, particles, and debris through the passageway 172. This may ensure accurate readings of air quality variables while minimizing deposition of droplets, particles, and debris on the sensor and within the passageway 172. The drift measurement sensor 150 may be positioned in the path of the airflow 114 through the cooling tower 100, with the inlet 174 of the drift measurement sensor 150 located upstream of the outlet 176 to direct the airflow into the inlet 174 of the drift measurement sensor 150. As shown in FIG. 1 , the drift measurement sensor 150 may be positioned at the air inlet 118 and the air outlet 130 of the cooling tower 100 to monitor the condition of the air as it enters and exits the cooling tower 100. In one embodiment, drift measurement sensor 150 includes a conductivity sensor for collecting water and detecting the conductivity of the collected water (see, e.g., FIGS. 20 and 21). Drift measurement sensor 150 may include a controller 151 that controls the operation of components of drift measurement sensor 150, including sensors 152, 154, and 156.Controller 151 may be in communication with controller 162 of cooling tower 100 to facilitate data communication between sensors 152, 154, 156 and controller 151. In some forms, controller 151 is omitted, and controller 162 of cooling tower 100 controls operation of the components of drift measurement sensor 150. It will be appreciated that other embodiments of the drift measurement sensors disclosed herein may include controllers similar to controller 151, although these controllers have generally been omitted from the relevant figures for clarity.

[0043]

[0055] Referring to FIG. 5 , the drift measurement sensor 150 can further include a dehumidifier, such as a heater 178. The heater 178 can be mounted in the conduit 170 and operated to dry the air entering the inlet 174 of the drift measurement sensor 150. The heater 178 can be mounted upstream of the sensor of the drift measurement sensor 150 to dry the air before it passes through the sensor. The heater 178 dries the air by increasing the dry-bulb temperature of the air and reducing the relative humidity of the air. The heater 178 can be used to reduce the relative humidity of the air and / or evaporate drift droplets to ensure proper operation of the PM2.5 sensor, PM10 sensor, and other sensors of the drift measurement sensor. In another embodiment, the dehumidifier of the drift measurement sensor 150 can include a vapor-permeable membrane configured to remove water vapor from the air. The membrane can be impermeable to salts and other dissolved solids but permeable to water. The membrane can be sized and shaped to allow efficient moisture removal while inhibiting particle buildup on the membrane.

[0044]

[0056] Drying the air entering the drift measurement sensor 150 can reduce the accumulation of drift droplets on the sensor in the passage 172 from drift droplets entering the drift measurement sensor 150. Water accumulation on the sensor can reduce the sensor's measurement accuracy and potentially cause sensor failure. In some configurations, the particulate matter sensor 156 can detect salts left behind by evaporated water droplets. Thus, the drift measurement sensor 150 can detect particulate matter in the airflow even when the heater 178 evaporates the water from the drift droplets. The heater 178 can be mounted to heat the air flowing through the passage 172 while minimizing obstruction of the passage 172. This configuration allows the heater 178 to heat the air while minimizing the accumulation of droplets, particles, and debris on the heater 178 and within the passage 172, which could interfere with sensor readings downstream of the heater 178. For example, the heater 178 can be flush with the inner surface of the tube 170.

[0045]

[0057] Controller 151 may operate heater 178 based on the temperature and / or relative humidity of the air. For example, controller 151 may operate heater 178 when the air is humid to dry the air and prevent water from accumulating inside tube 170, on the sensor, or on other parts of drift measurement sensor 150. For example, controller 151 may be programmed to calculate the probability of plume formation based on the temperature and humidity of the air, and may operate heater 178 to, for example, reduce the probability of plume formation and condensation within drift measurement sensor 150.

[0046]

[0058] Referring to FIG. 6 , the drift measurement sensor 150 can include a cooler 180, such as a cooling coil. The cooler 180 can be mounted within the passageway 172 and operated to cool the air entering the inlet 174 of the drift measurement sensor 150. The cooler 180 can be mounted upstream of the sensor of the drift measurement sensor 150 and used to condense water from the air before the air flows through the sensor. Similar to the heater 178, drying the air entering the drift measurement sensor 150 can help reduce water and moisture buildup on the sensor within the passageway 172. The cooler 180 can condense moisture from the air and collect drift droplets within the passageway 172 before they reach the sensor. The cooler 180 can be mounted within the passageway 172 to minimize obstruction of the passageway 172 while cooling the air flowing therethrough. Such a configuration allows the cooler 180 to cool the air and condense moisture from the air while minimizing the accumulation of droplets, particles, and debris on the cooler 180 and within the passageway 172 that may interfere with sensor readings downstream of the cooler 180. For example, the cooler 180 may have a cooling surface that is flush with the inner surface of the tubes 170. In some embodiments, the cooler 180 may collect moisture condensed from the air and measure the conductivity of this condensation to determine the drift rate of the cooling tower, as described in more detail below in connection with the drift measurement sensor 400 of FIG. 20.

[0047]

[0059] 7, in another embodiment, the drift measurement sensor 150 can include both a heater 178 and a cooler 180. The heater 178 and cooler 180 can be mounted within the passageway 172 to dry the air before it reaches the sensor, as described above. The cooler 180 can cool the air and condense moisture from the air before it flows through the heater 178. The heater 178 can heat the air before it flows over the sensor, further assisting in drying the air. The heater 178 can be operated to return the temperature of the air to the temperature of the air entering the inlet 174. While the heater 178 is illustrated downstream of the cooler 180, in other embodiments, the heater 178 can be located upstream of the cooler 180 to raise the dry-bulb temperature of the air before the cooler 180 condenses moisture from the air.

[0048]

[0060] 8 , drift measurement sensor 150 can include additional sensors to monitor other conditions of the air flowing through drift measurement sensor 150. Drift measurement sensor 150 can include a carbon monoxide (CO) sensor 182, a carbon dioxide (CO) sensor 184, and a volatile organic compound (VOC) sensor 186. These sensors can be mounted within passageway 172 of drift measurement sensor 150 to monitor the amount of carbon monoxide, carbon dioxide, and volatile organic compounds in the air. If drift measurement sensor 150 includes heater 178 and / or cooler 180, CO sensor 182, CO sensor 184, and VOC sensor 186 can be mounted within passageway 172 downstream of heater 178 and / or cooler 180. Other sensors can also be included within drift measurement sensor 150 to measure the amount of other chemicals, bacteria, and / or organisms in the air.

[0049]

[0061] Referring to FIG. 9 , the drift measurement sensor 150 can include a filter 188. The filter 188 can be mounted to the inlet 174 of the drift measurement sensor 150 to block debris and larger particles from flowing through the drift measurement sensor 150 while allowing air and drift particles to pass therethrough. For example, the filter 188 can block leaves, dust, and other such debris from entering the drift measurement sensor 150. Such debris can interfere with the sensor's measurements within the passage 172 of the drift measurement sensor 150. Furthermore, such debris can clog the passage 172, restricting or limiting airflow therethrough. For example, the filter 188 can include a mesh screen having a pore size in the range of about 1 mm to about 2 mm. The filter 188 can be a relatively coarse screen that blocks the entry of larger particles and debris while reducing the filter's interference with airborne particulate matter entering the drift measurement sensor 150.

[0050]

[0062] 10 , drift measurement sensor 150 includes air sampling device 150A that includes conduit 170 and damper 190. Conduit 170 and damper 190 cooperate to provide an air velocity within conduit 170 that corresponds to the air velocity outside conduit 170. Damper 190 may be mounted to inlet 174 and may prevent debris (e.g., leaves) from entering drift measurement sensor 150. Damper 190 helps prevent debris from entering passageway 172 and reaching the sensor, interfering with measurements by the sensor and / or clogging passageway 172. Damper 190 may also be adjusted to provide a specific air velocity through passageway 172.

[0051]

[0063] The damper 190 can pivot to close or open the inlet 174 to prevent or allow air to flow through the drift measurement sensor 150. For example, the damper 190 can be closed when the drift measurement sensor 150 is not in use or when it is raining. The damper 190 can be pivoted by a motor in response to a control signal from the controller 162, for example. Referring to FIG. 11 , in another embodiment, the drift measurement sensor 150 can include a damper 192 mounted at the outlet 176 in addition to or instead of the damper 190 at the inlet 174. The damper 192 can prevent debris from entering the drift measurement sensor 150 through the outlet 176 and interfering with sensor measurements and / or clogging the passageway 172. The damper 192 can pivot to close or open the outlet 176 to prevent or allow air to flow in and out of the drift measurement sensor 150 through the outlet 176. For example, the damper 192 may be closed when the drift measurement sensor 150 is not in use or when it is raining. The damper 192 may be pivoted by a motor in response to a control signal from the controller 162, for example. The damper 192 may be adjusted to provide a particular air velocity through the passageway 172.

[0052]

[0064] 12, a drift measurement sensor 400 is shown that is similar in many respects to the drift measurement sensor 150 described above, with the differences being emphasized in the following discussion. Drift measurement sensor 400 may be mounted to the air inlet 118 and / or air outlet 130 of cooling tower 100 to monitor the quality of the air entering the cooling tower 100 and / or after it leaves the cooling tower 100. Drift measurement sensor 400 includes a conduit, such as tube 402, having a passageway 404 extending from an inlet 406 to an outlet 408. Like drift measurement sensor 150 described above, drift measurement sensor 400 may include a temperature sensor 420, a relative humidity sensor 422, and a particulate matter sensor 424.

[0053]

[0065] The conduit 402 of the drift measurement sensor 400 may have a bend, such as a bend 410, that changes the direction of the airflow in the passage 404 as the air travels from the inlet 406 to the outlet 408. The bend 410 redirects the airflow in the conduit 402 and promotes equal or similar air velocities in the passage 404 relative to the airflow in the cooling tower 100. The similar air velocities inside and outside the passage 404 ensure that all particles in the airflow outside the drift measurement sensor 400 enter the passage 404. In the exemplary embodiment shown, the conduit 402 has a first portion 412 that extends from the inlet 406 to the bend 410 and a second portion 414 that extends from the bend 410 to the outlet 408. The first and second portions 412, 414 extend at right angles to each other. In one embodiment, bend 410 is a 90-degree bend such that the direction in which air exits drift measurement sensor 400 is substantially perpendicular to the direction in which air enters drift measurement sensor 400. While a 90-degree bend is illustrated, other bend angles may be used, including, by way of example, bends between 10 and 89 degrees. By including bend 410 in conduit 402, as bend 410 curves, a portion of the air and drift matter impacts the sidewalls of passageway 404, redirecting the airflow in a different direction, e.g., toward outlet 408. As air flows through bend 410, drift matter carried in the air is separated from the air due to inertial impaction. In other words, as the air and drift matter flow through bend 410, they impact the sidewalls of passageway 404, causing the drift matter in the air to lose velocity and / or accumulate on the sidewalls of passageway 404. Thus, bend 410 removes a portion of the drift matter from the airflow, reducing the amount of water droplets reaching sensors 420, 422, and 424. As mentioned above, water on the sensor can reduce the accuracy of the sensor data and / or cause the sensor to fail. In one embodiment, drift measurement sensor 400 is oriented such that first portion 412 is longitudinally below second portion 414, such that gravity pulls drift that accumulates in bend 410 downward and out of tube 402 via inlet 406.

[0054]

[0066] 13, in one embodiment, drift measurement sensor 400 can include a heater 426 for heating and drying the air flowing through passageway 404 before the air flows over sensors 420, 422, 424. Heater 426 can be mounted downstream of bend 410 to dry the air after some of the water has been removed from the air flowing through bend 410 as described above.

[0055]

[0067] 14, the drift measurement sensor 400 can include a cooler 428 for cooling the air and condensing moisture from the air. The cooler 428 can thus dry the air flowing through the passage 404 before the air flows over the sensors 420, 422, 424. The cooler 428 can be mounted downstream of the bend 410 to dry the air after some of the water has been removed from the air flowing through the bend 410 as described above. Referring to FIG. 15, the drift measurement sensor 400 can include both a heater 426 and a cooler 428 that can be operated to heat and dry the air before it flows over the sensors 420, 422, 424.

[0056]

[0068] 16, drift measurement sensor 400 can include additional sensors to monitor other conditions of the air flowing through drift measurement sensor 400. Drift measurement sensor 400 can include a CO sensor 430, a CO2 sensor 432, and a VOC sensor 434. These sensors can be mounted within passage 404 of drift measurement sensor 400 to monitor the amount of carbon monoxide, carbon dioxide, and volatile organic compounds in the air. CO sensor 430, CO2 sensor 432, and VOC sensor 434 can be mounted downstream of bend 410 after a portion of the larger droplets have been removed from the airflow through bend 410. If drift measurement sensor 400 includes heater 426 and / or cooler 428, CO sensor 430, CO2 sensor 432, and VOC sensor 434 can be mounted downstream of heater 426 and / or cooler 428 within passage 172. Other sensors may be included in the drift measurement sensor as well to measure air quality, such as the amount of other chemicals, bacteria, and / or organisms in the air.

[0057]

[0069] With reference to FIG. 17 , the drift measurement sensor 400 may include a filter 436. The filter 436 may be mounted to the inlet 406 of the drift measurement sensor 400 to prevent debris from entering or flowing through the drift measurement sensor 400, as described above with respect to the previous embodiments. With reference to FIG. 18 , the drift measurement sensor 400 may include a damper 438 mounted to the inlet 406. The damper 438 may selectively open or close the inlet 406 and / or prevent debris from entering or flowing through the drift measurement sensor 400, as described above with respect to the previous embodiments. With reference to FIG. 19 , the drift measurement sensor 400 may further include a damper 440 mounted to the outlet 408. The damper 440 may selectively open or close the outlet 408 and / or prevent debris from entering the drift measurement sensor 400 via the outlet, as described above with respect to the previous embodiments.

[0058]

[0070] 20 , the cooler 428 may include a discharge conduit 442 for draining condensation from the drift measurement sensor 400. For example, the cooler 428 may be operated to condense moisture from the air as it flows through the passage 404 of the conduit 402. The condensed moisture may be collected and / or directed to the discharge conduit 442 to remove the moisture from the drift measurement sensor 400. The condensed moisture may flow away from the drift measurement sensor 400 through a passage 444 of the discharge conduit 442. For example, the condensed moisture may flow through the discharge conduit 442 into the sump 132 of the cooling tower 100. The drift measurement sensor 400 may include a conductivity sensor 446 for measuring the conductivity of the liquid flowing through the discharge conduit 442. In another embodiment, the drift measurement sensor 400 includes a pH sensor instead of or in addition to the conductivity sensor 446. Similar to the techniques discussed herein for conductivity data and particulate matter data, data from the drift measurement sensor 400 regarding the pH of the water collected by the drift measurement sensor 400 can be used to determine abnormal changes in drift.

[0059]

[0071] The controller 162 receives condensate liquid conductivity data from the conductivity sensor 446 and can use the conductivity data in assessing the drift condition of the cooling tower 100. For example, the conductivity of the condensate of the drift measurement sensor 400 mounted on the air outlet 130 of the cooling tower 100 can be compared to the conductivity of the condensate of the drift measurement sensor 400 mounted on the air inlet 118. As another example, the conductivity of the condensate can be compared to the conductivity of the fluid in the sump 132 to detect whether the drift rate of the cooling tower 100 is increasing. In one example where no drift is occurring, the conductivity of the liquid collected by the drift measurement sensor 400 may be approximately 0 μS / cm. If a normal or acceptable amount of drift is present in the cooling tower 100, some of the liquid collected by the drift measurement sensor 400 may be drift, causing the conductivity of the liquid collected by the drift measurement sensor 400 to increase. For example, if the conductivity of the fluid in the container is 1500 μS / cm and the drift rate is a normal amount of about 0.005%, the conductivity of the liquid collected by the drift measurement sensor 400 may be about 50 μS / cm. If an abnormally large amount of drift is present, a larger portion of the liquid collected by the drift measurement sensor 400 will be drift, further increasing the conductivity of the collected liquid. Continuing with the example above where the conductivity of the fluid in the container is 1500 μS / cm, if the drift rate is a higher 0.015%, the conductivity of the liquid collected by the drift measurement sensor 400 may be about 150 μS / cm. The controller 162 can determine that the drift rate is high based on the conductivity of the liquid collected by the drift measurement sensor 400. For example, the conductivity of the collected liquid is outside of an expected range for a normal drift rate, such as a range of 50 μS / cm + / - 25 μS / cm.

[0060]

[0072] 21, drift measurement sensor 400 can include a cooler 428. Cooler 428 can be used to perform condensation and sample the condensate without including temperature sensor 420, relative humidity sensor 422, and / or particulate matter sensor 424.

[0061]

[0073] Referring to FIG. 22 , a drift measurement sensor 500 according to another embodiment is shown, which is similar in many respects to the drift measurement sensors described above, with the differences being emphasized in the following discussion. The drift measurement sensor 500 includes a conduit 502 defining a passageway 504. The conduit 502 includes a first bend 505 and a second bend 507. Air and drift enter the conduit 502 through an inlet 506, flow through a straight portion 508 of the passageway 504, and reach the first bend 505. The first bend 505 is a U-shaped bend, bending approximately 180 degrees. As the air flows through the first bend 505, drift carried in the air separates from the air as it flows around the bend 505 due to inertial impaction, as described above. The air and remaining drift flow from the first bend 505 to the second bend 507, where the drift can be further separated from the air due to inertial impaction. The second bend 507 is a U-shaped bend, bending approximately 180 degrees. Drift removed from the air by redirecting the air at the first and second bends 505, 507 can be collected in the second bend 507 for testing and / or removal from the drift measurement sensor 500. The second bend 507 can be oriented such that its center 510 is vertically lower than the ends 512, 514 of the bend 507 to assist in the gravity collection of separated drift. Air and any remaining drift in the air flow from the second bend 507 through a straight section 516 to an outlet 518.

[0062]

[0074] As described above, a discharge tube 520 can be mounted in the conduit 502 at the second bend 507 to discharge collected drift (e.g., water and particulates) from the drift measurement sensor 500. The discharge tube 520 can be mounted in the center 510, e.g., at the lowest vertical point, to allow the collected drift to be collected and guided into the discharge tube 520. A conductivity sensor 522 can be mounted in the discharge tube 520 to measure the conductivity of the collected drift as it flows through the discharge tube 520. The conductivity of the collected drift can be used to determine the amount of particulates in the air, e.g., the amount of particulates removed by inertial impaction as the air and drift flow through the first bend 504 and the second bend 507.

[0063]

[0075] In one embodiment, the drift measurement sensor 500 in FIG. 22 and other figures includes a dehumidifier 513 to increase water collection. The water collected by the dehumidifier is drift water, which allows for more accurate analysis of the collected water than if the water were combined with water condensed from the ambient air. The dehumidifier may include, for example, a cooler, a heater, a combination heater and cooler, and / or a vapor permeable membrane.

[0064]

[0076] 23 , in one embodiment, drift measurement sensor 500 includes a temperature sensor 524, a relative humidity sensor 526, and a particulate matter sensor 528 for monitoring other aspects of the air flowing through drift measurement sensor 500. Temperature sensor 524, relative humidity sensor 526, and particulate matter sensor 528 may be mounted in a portion of conduit 502 to contact the air after drift is separated from the air at first bend 504 and / or second bend 507. Other sensors, including, for example, a CO sensor, a CO2 sensor, and / or a VOC sensor, may also be in communication with passageway 504 of drift measurement sensor 500. These sensors may be mounted in straight portion 516 of the conduit downstream of second bend 507.

[0065]

[0077] Referring to FIG. 24 , a drift measurement sensor 600 according to another embodiment is shown, which is similar in many respects to the drift measurement sensors of the other embodiments described above, with the differences being emphasized in the following discussion. The drift measurement sensor 600 includes an air sampling device having a body, such as a conduit 602, with an interior or passageway 604 through which air and drift matter can flow. The conduit 602 may include a sidewall extending around the passageway 604. The conduit 602 includes one or more inlet openings 606 and an outlet 608. Air and drift matter can enter the conduit 602 through the inlet openings 606 and flow along the passageway 604 to reach the outlet 608. The inlet openings 606 are through openings formed in the sidewall of the conduit 602, allowing air to enter the conduit 602 substantially perpendicular to the central axis 607 of the passageway 604. A portion of the drift matter can be separated from the air by inertial impact of the air against an interior surface 609 as the air flow changes direction to flow along the passageway 604.

[0066]

[0078] The air sampling device of the drift measurement sensor 600 of FIG. 24 includes a fan assembly 610 having a motor 612 that rotates a fan 614. The fan assembly 610 may be mounted at the end of the conduit 602 near the outlet 608. The fan assembly 610 may be operated to move air through the conduit 602 from the inlet opening 606 to the outlet 608. Operation of the fan assembly 610 may draw air and drift into the conduit 602 through the inlet opening 606 and force air out of the conduit 602 through the outlet 608. Operating the fan assembly 610 may help ensure that a representative sample of the air flowing over the drift measurement sensor 600 flows through the passageway 604 of the drift measurement sensor 600 for monitoring air quality. For example, the fan assembly 610 may be operated to achieve a constant air velocity through the drift measurement sensor 600 to provide more uniform drift measurements at all fan speeds of the associated heat exchange device. Fan assembly 610 can be operated to move air past drift measurement sensor 600 at approximately the same speed as air flowing through the cooling tower around drift measurement sensor 600. Drift measurement sensor 600 (e.g., a controller for drift measurement sensor 600) can receive a signal indicative of the airflow velocity around drift measurement sensor 600 and increase, decrease, or maintain the speed of fan assembly 610 to match the airflow velocity within drift measurement sensor 600 to the airflow velocity outside drift measurement sensor 600 in the cooling tower. For example, drift measurement sensor 600 can include a conduit-mounted air velocity sensor 619 to measure the airflow velocity outside drift measurement sensor 600. As another example, a cooling tower can include an air velocity sensor inside, at the inlet, or at the outlet of the cooling tower, and the cooling tower controller can communicate the air velocity data to drift measurement sensor 600. In some forms, the drift measurement sensor 600 receives from the cooling tower an operating variable of the fan assembly 102 (e.g., the power or current provided to the fan assembly, or the speed of the fan assembly) that is indicative of the speed of the airflow through the cooling tower.It will be appreciated that other embodiments of the drift measurement sensor discussed herein, including fan assemblies, may operate similarly to drift measurement sensor 600 .

[0067]

[0079] Drift measurement sensor 600 includes a temperature sensor 616, a relative humidity sensor 618, and a particulate matter sensor 620 mounted within passageway 604 between inlet opening 606 and outlet 608. As described above, temperature sensor 616, relative humidity sensor 618, and particulate matter sensor 620 are used to assess the condition of the air flowing through conduit 602, which can be used to determine whether cooling tower 100 is experiencing an increased drift rate.

[0068]

[0080] 25, the drift measurement sensor 600 can include a heater 622. The heater 622 can be positioned within the passageway 604 between the inlet opening 606 and the sensor. The heater 622 can be operable to increase the temperature of the air and / or dry the air, as described above with respect to other embodiments, to reduce or remove water droplets from the air and prevent water from accumulating on the sensor and interfering with measurements.

[0069]

[0081] 26, the drift measurement sensor 600 can include a cooler 624. The cooler 624 can be positioned within the passageway 604 between the inlet opening 606 and the sensor. The cooler 624 can operate to dehumidify the air, as described above with respect to other embodiments. The cooler 624 can condense moisture from the air and drift, preventing moisture or water from building up on the sensor and interfering with measurements.

[0070]

[0082] 27, drift measurement sensor 600 can include both a heater 622 and a cooler 624. Heater 622 and cooler 624 can be positioned within passageway 604 between inlet opening 606 and the sensor. Heater 622 and cooler 624 can be operated to dry water droplets from the air and / or dehumidify the air upstream of the sensor, as described above with respect to other embodiments.

[0071]

[0083] 28 , in one embodiment, drift measurement sensor 600 includes additional sensors for measuring and monitoring other conditions of the air flowing through drift measurement sensor 600. Drift measurement sensor 600 may include a carbon monoxide (CO) sensor 626, a carbon dioxide (CO) sensor 628, and a volatile organic compound (VOC) sensor 630. These sensors may be mounted within passageway 604 of drift measurement sensor 600 to monitor the amount of carbon monoxide, carbon dioxide, and volatile organic compounds in the air. If drift measurement sensor 600 includes heater 622 and / or cooler 624, CO sensor 626, CO sensor 628, and VOC sensor 630 may be mounted downstream of heater 622 and / or cooler 624 within passageway 604. Other sensors may also be included within drift measurement sensor 600 to measure the amount of other chemicals, bacteria, and / or organisms in the air.

[0072]

[0084] 29, in one embodiment, drift measurement sensor 600 includes a filter 632 at inlet opening 606. Filter 632 can prevent debris and large particles (relative to drift particles) from entering drift measurement sensor 600. Filter 632 can be, for example, a mesh screen.

[0073]

[0085] 30, drift measurement sensor 600 may include a damper 634 at inlet opening 606. Damper 634 may pivot to selectively open or close inlet opening 606 and / or prevent debris (e.g., leaves) from entering drift measurement sensor 600, as described above with respect to other embodiments. Referring to FIG. 31, drift measurement sensor 600 may also include a damper 636 mounted at outlet 608. Damper 636 may pivot to selectively open or close outlet 608 and / or prevent debris from entering drift measurement sensor 600 via outlet 608, as described above with respect to other embodiments.

[0074]

[0086] 32 and 33, drift measurement sensor 600 can include a cooler 624 with (see FIG. 32) or without (see FIG. 33) a temperature sensor 616, a relative humidity sensor 618, and / or a particulate matter sensor 620. Cooler 624 can include an exhaust pipe 638. As described above, moisture condensed from air flowing through drift measurement sensor 600 can be removed from drift measurement sensor 600 via exhaust pipe 638. Cooler 624 can collect the condensate and direct the moisture to exhaust pipe 638. Drift measurement sensor 600 can include a conductivity sensor 641 for measuring the conductivity of the condensate flowing through exhaust pipe 638, as described above. In an embodiment in which drift measurement sensor 600 includes temperature sensor 616 and relative humidity sensor 618, the temperature sensor 616 and relative humidity sensor 618 can be used to control the operation of cooler 624. For example, temperature and humidity measurements can be used to determine the amount of cooling to provide by cooler 624 to condense moisture from the air. Alternatively or additionally, temperature sensor 616, relative humidity sensor 618, and / or particulate matter sensor 620 can be used to monitor drift as described above.

[0075]

[0087] Referring to FIG. 34 , in one embodiment, the conduit 602 of the drift measurement sensor 600 may include a bend 640 for separating drift from air by inertial impaction, as described above. The bend 640 may be a substantially U-shaped bend between the inlet 606 and the outlet 608. As air flows along the passageway 604 and through the bend 640, drift may impact the inner surface of the conduit 602 and accumulate thereon. The drift may flow along the sidewalls of the bend 640 and accumulate within the bend 640. For example, a central portion 642 of the bend 640 may be positioned vertically lower than the inlet portion 644 and the outlet portion 646 of the bend 640, so that the drift may flow by gravity along the inner surface of the conduit 602 to the central portion 642 of the bend 640. The drift measurement sensor 600 may include, for example, an exhaust pipe 648 connected to the bend 640 at the lowest point of the bend 640 where the drift may accumulate or accumulate. The drift flows through a discharge line 648 and is removed from the drift measurement sensor 600. The drift measurement sensor 600 may include a conductivity sensor 641 for measuring the conductivity of the condensate flowing through the discharge line 648, as described above. In another embodiment, the drift measurement sensor 600 has a liquid flow sensor instead of or in addition to the conductivity sensor 641. The controller 162 can use data from the liquid flow sensor to determine changes in the amount of drift in the cooling tower.

[0076]

[0088] Referring to FIG. 35, the drift measurement sensor 600 may further include a temperature sensor 616, a relative humidity sensor 618, and / or a particulate matter sensor 620 positioned after the bend 640 where at least a portion of the drift has been removed from the air by the bend 640 as described above.

[0077]

[0089] Referring to FIG. 36A, a heat exchanger 700 is provided in accordance with another embodiment. The heat exchanger 700 may operate as a fluid cooler, such as a closed-circuit cooling tower, or as an evaporative condenser, as some examples. The heat exchanger 700 is similar in many respects to the cooling tower 100 of FIG. 1A described above, with the differences being emphasized in the following discussion. The heat exchanger 700 includes an airflow generator, such as a fan assembly 702, an indirect heat exchanger 704, and an evaporative liquid distribution system 706 for dispersing a liquid, such as water, over the indirect heat exchanger 704.

[0078]

[0090] Each indirect heat exchanger 704 includes an inlet header 705 for receiving a fluid, an outlet header 707, and a heat exchange element 715, such as a pillow plate heat exchanger 717, connecting the inlet and outlet headers 705, 707. In other embodiments, a different heat exchange element 715, such as a coil, a plate heat exchanger, and / or a fin-and-tube heat exchanger, may be utilized instead of or in addition to the pillow plate heat exchanger 717. The fluid enters the inlet header 705, travels through the pillow plate heat exchanger 717, and is collected in the outlet header 707 before flowing out of the indirect heat exchanger 704. The fluid received at the inlet header 705 may include, for example, liquid water, water vapor (e.g., steam), a mixture of liquid water and water vapor, ammonia, brine, and / or glycol (e.g., propylene, ethylene). In one embodiment, the fluid received by inlet header 705 may include a refrigerant such as R-134a, R410, R404, and / or R744. In some embodiments, the positions of inlet header 705 and outlet header 707 may be reversed, with outlet header 707 located above inlet header 705.

[0079]

[0091] In embodiments in which the heat exchange element 715 includes one or more coils, each coil may have multiple turns between the inlet header 705 and the outlet header 707. In one embodiment, the coil includes one or more tubes, each having an interior through which fluid can pass and a sidewall extending around the interior. The coils can have multiple configurations, for example, a straight tube extending between headers or a serpentine tube having straight sections connected by bends. The coils may or may not include fins.

[0080]

[0092] Rotation of the fan in fan assembly 702 moves air from air inlet 711, through filter 709, through pillow plate heat exchanger 717, through drift eliminator 734, upward through fan assembly 702, and out air outlet 713 of heat exchanger apparatus 700. In one approach, because the temperature of the fluid within pillow plate heat exchanger 717 is higher than the air flowing over it, heat is transferred from the hot fluid inside pillow plate heat exchanger 717 to the cooler airflow moving over the exterior of pillow plate heat exchanger 717 through the tube sidewalls of pillow plate heat exchanger 717.

[0081]

[0093] The evaporative liquid distribution system 706 includes a liquid supply valve connected to a liquid supply. The liquid utilized by the evaporative liquid distribution system 706 can include, for example, water (e.g., tap water, rainwater, and / or non-potable water). In some embodiments, the liquid distribution system 706 receives water from a water treatment system that converts raw water into treated water with properties and / or additives (e.g., antifungal, antibacterial) suitable for distribution within the heat exchange apparatus 700. In one embodiment, the liquid supply valve includes a make-up valve 716. The make-up valve 716 can be opened to dispense liquid into the sump 720 of the heat exchange apparatus 700. The make-up valve 716 can be opened to dispense liquid into the sump 720 when the sump 720 is empty, when the liquid level in the sump 720 is low, and / or to introduce new liquid into the heat exchange apparatus 700.

[0082]

[0094] The vaporized liquid distribution system 706 includes a pump 722, a conduit 718, and a nozzle 714. The pump 722 pumps liquid from a sump 720 via a conduit 718 to a nozzle 714 positioned above a pillow plate heat exchanger 717 of the indirect heat exchanger 704. The pump 722 can be operated to distribute the liquid from the sump 720 over the pillow plate heat exchanger 717 to assist in cooling the fluid flowing through the pillow plate heat exchanger 717. The vaporized liquid absorbs heat from and removes heat from the pillow plate heat exchanger 717. Additionally, a portion of the vaporized liquid evaporates, further removing heat from the pillow plate heat exchanger 717. The unevaporated liquid falls back into the sump 720.

[0083]

[0095] As such, the liquid distribution system 706 can operate in conjunction with the fan assembly 702 to assist in removing heat from the fluid flowing through the pillow plate heat exchanger 717. For example, the heat exchanger 700 can have a dry mode in which the controller 162 operates the fan assembly 702 to generate airflow through the pillow plate heat exchanger 717 but does not operate the pump 722. The controller 162 may determine that the heat exchanger 700 in the dry mode cannot achieve a return fluid setpoint required by (for example) an HVAC controller. The controller 162 can reconfigure the heat exchanger 700 to a wet mode to achieve the return fluid setpoint. As another example, the controller 162 can reconfigure the heat exchanger 700 to operate in a wet mode to conserve power or if it is more cost-effective for the heat exchanger 700 to operate in the wet mode.

[0084]

[0096] In wet mode, controller 162 operates pump 722 to spray evaporated liquid from sump 720 onto pillow plate heat exchanger 717. Heat exchanger apparatus 700 may include a flow meter 726 and a temperature sensor 728 attached to conduit 718 to monitor the flow rate and temperature of the liquid being dispensed onto pillow plate heat exchanger 717.

[0085]

[0097] Heat exchanger 700 may include a temperature sensor 730 and a conductivity sensor 732 in sump 720 to monitor the temperature and conductivity of the fluid in sump 720. Controller 162 may receive data from temperature sensor 720 and / or conductivity sensor 732. Sump 720 may have a drain valve 724 that can be opened (e.g., by controller 162) to drain fluid from sump 720 and out of circulation within cooling tower 700. Drain valve 724 may be opened to drain liquid from sump 720 if, for example, there is too much liquid in sump 720, or to drain liquid completely from sump 720 as part of a liquid switching process if, for example, the conductivity or pH of the liquid exceeds a threshold value.

[0086]

[0098] Similarly, as part of the fail-safe operation of the heat exchanger 700, the drain valve 724 can be opened to drain liquid from the sump 720. For example, if the controller 162 detects an abnormal change in the drift of the heat exchanger 700 and detects an increased risk of bacterial contamination, the controller 162 can open the drain valve 724 and notify maintenance personnel of the problem. The controller 162 can monitor the liquid in the sump 720 for the risk of bacterial contamination using water sample analysis and / or biofilm sensors.

[0087]

[0099] The heat exchanger 700 may include one or more drift measurement sensors 150 according to the embodiments described above to monitor one or more variables of the cooling tower 100, such as variables related to air quality conditions. As shown in FIG. 36A , the heat exchanger 700 may include a drift measurement sensor 150 at one or both of the air outlet 713 and the air inlet 711 of the heat exchanger 700. As discussed in detail above, the drift measurement sensor 150 includes a sensor for monitoring a variable indicative of drift. The controller 162 may monitor a change in the monitored variable and determine whether the change indicates an increase in the drift rate of the cooling tower beyond an expected or acceptable amount. For example, if the liquid dispersion system 706 is turned on, the controller 162 may expect an increase in the amount of particulate matter detected by the drift measurement sensor 150 at the outlet 713 downstream of the pillow plate heat exchanger 717. The controller 162 may monitor the increase in particulate matter at the air outlet 713 and determine whether the increase in particulate matter exceeds an expected or acceptable amount. If the increase in particulate matter exceeds an acceptable amount (eg, exceeds an upper predetermined error range), the controller 162 determines that the drift rate of the heat exchange device 700 has increased significantly.

[0088]

[0100] The drift measurement sensor 150 can be positioned at various locations in the heat exchanger 700 to monitor drift. Referring to Figure 36B, an alternative configuration of the heat exchanger 700 is provided. In this configuration, the drift measurement sensor 150 is mounted downstream of the indirect heat exchanger 704 and upstream of the fan assembly 702.

[0089]

[0101] The controller 162 can compare air variables detected at the air inlet 711 upstream of the indirect heat exchanger 704 and the air inlet 711 downstream of the indirect heat exchanger 704 after the drift eliminator 734 to determine the drift condition using the techniques described above. For example, with reference to FIG. 3A , the controller 162 can determine that the heat exchanger device 700 has an unacceptable drift condition based on the speed of the fan assembly 102, the spray water status (e.g., whether the pump 722 is running), the conductivity of the liquid in the sump 720, and the air variables (e.g., particulate matter, relative humidity, and dry bulb temperature) detected by the drift measurement sensors 150 at the air inlet 711 and air outlet 713 of the heat exchanger device 700.

[0090]

[0102] 37A, a cooling tower 800 is provided in accordance with another embodiment. The cooling tower 800 is similar in many respects to the cooling towers described above, with the differences being emphasized in the following discussion. The cooling tower 800 includes an airflow generator, such as a fan assembly 802, an indirect heat exchanger 804, a liquid distribution system 806, and an adiabatic precooler system 803. The adiabatic precooler system 803 includes a liquid-absorbent material, such as one or more insulation pads 808, and an evaporative liquid distribution system 806 for dispersing a liquid, such as water, onto the insulation pads 808 upstream of the indirect heat exchanger 804.

[0091]

[0103] The fan assembly 802 includes a fan 810 and a motor 812, which rotates the fan 810 to generate airflow along a path 809 relative to the housing 801 of the cooling tower 800. Specifically, the fan assembly 802 draws air into the air inlet 811 of the housing 801, through the insulating pad 808, and from the insulating pad 808 to the indirect heat exchanger 804. The insulating pad 808 can be made of a liquid-absorbent material through which air can flow, including, by way of example, cellulose and / or impregnated cellulose fibers. As another example, the liquid-absorbent material can include inorganically impregnated glass fibers. As yet another example, the insulating pad 808 is an insulating preheater and can include a microporous membrane that allows liquid water to pass through. A drift sensor 150 downstream of the insulating pad 808 can detect liquid droplets carried by the airflow through the membrane.

[0092]

[0104] Each indirect heat exchanger 804 includes an inlet header 805 for receiving a fluid, an outlet header 807, and a heat exchange element, such as a finned tube heat exchanger 817, connecting the inlet and outlet headers 805, 807. Other heat exchange elements, such as microtubes, serpentine tubes, plate heat exchangers, etc., may also be used. The fluid enters the inlet header 805, travels through the finned tube heat exchanger 817, and is collected in the outlet header 807 before flowing out of the indirect heat exchanger 804. The fluid received at the inlet header 805 may include, for example, liquid water, water vapor (e.g., steam), a mixture of liquid water and water vapor, ammonia, brine, and / or glycol (e.g., propylene, ethylene). In one embodiment, the fluid received at the inlet header 805 may include a refrigerant, such as R-134a, R410, R404, and / or R744.

[0093]

[0105] Rotation of fan 810 moves air from air inlet 811, through insulation pad 808, through finned tube heat exchanger 817, upward through fan assembly 802, and out of heat exchanger apparatus 800 via air outlet 813. In one approach, the temperature of the fluid within finned tube heat exchanger 817 is higher than the air flowing over it, so heat is transferred through finned tube heat exchanger 817 from the hot fluid inside finned tube heat exchanger 817 to the cooler airflow moving over the exterior of finned tube heat exchanger 817.

[0094]

[0106] Evaporative liquid distribution system 806 includes a liquid supply valve connected to a liquid supply. The liquid utilized by liquid distribution system 806 may be, for example, water (e.g., tap water, rainwater, and / or non-potable water). In some embodiments, the liquid distribution system receives water from a water treatment system that converts raw water into treated water with properties and / or additives (e.g., antifungal, antibacterial) suitable for use in heat exchange apparatus 800. In one embodiment, the liquid supply valve includes a make-up valve 816. Make-up valve 816 can be opened to direct liquid into sump 820 of cooling tower 800.

[0095]

[0107] The evaporative liquid distribution system 806 further includes a pump 822 in a sump 820. The pump 822 is operable to pump liquid from the sump 820 through a conduit 818 to one or more outlets of the evaporative liquid distribution system 806, such as a nozzle 814. The nozzle 814 directs the liquid onto an insulating pad 808. The controller 162 can control the pump 822 to cause the evaporative liquid distribution system 806 to distribute the liquid onto the insulating pad 808 to increase the efficiency of the indirect heat exchange process. For example, the insulating pad 808 is positioned in the air flow path upstream of the finned tube heat exchanger 817. When the insulating pad 808 is saturated with liquid from the liquid distribution system 806, the liquid in the insulating pad 808 evaporates into the air passing through the pad 808, lowering the temperature of the air before it passes over the finned tube heat exchanger 817. The cooled air passes over the finned tube heat exchanger 817, increasing the efficiency of the indirect heat exchange process. Liquid that is not absorbed by the insulating pad 808 can collect in a sump 820 positioned below the insulating pad 808 .

[0096]

[0108] Cooling tower 800 may include a temperature sensor 830 and a conductivity sensor 832 associated with sump 820 to monitor the temperature and conductivity of the fluid within sump 820. Controller 162 may receive data from temperature sensor 830 and / or conductivity sensor 832. Sump 820 may have a drain valve 824 that can be opened (e.g., by controller 162) to drain fluid from sump 820 and out of circulation within cooling tower 800. Drain valve 824 may be opened to drain fluid from sump 820, for example, if there is too much liquid in sump 820, or to drain fluid from sump 820 as part of a liquid switching process, for example, if the conductivity or pH of the liquid exceeds a threshold value.

[0097]

[0109] Cooling tower 800 may include one or more drift measurement sensors 150 according to the embodiments described above to monitor one or more variables in cooling tower 800, such as variables related to air quality conditions. As shown in FIG. 37A , cooling tower 800 may include drift measurement sensors 150 at one or more of cooling tower 800's outlet 813 and air inlet 811. As discussed in detail above, drift measurement sensors 150 include one or more sensors to monitor one or more variables indicative of characteristics of the airflow received by drift measurement sensor 150. Controller 162 may monitor changes in the monitored variables and determine whether the changes indicate an increase in the cooling tower's drift rate beyond an expected or acceptable amount. For example, if evaporative liquid dispersion system 806 is turned on and pump 822 begins pumping fluid, controller 162 may expect drift measurement sensor 150 to detect an increase in the amount of particulate matter downstream of finned-tube heat exchanger 817, e.g., at air outlet 813. By monitoring the increase in particulate matter at the air outlet 813 and determining whether the increase in particulate matter exceeds an expected or acceptable amount, the controller 162 can determine that the heat exchanger 800 has an undesirable or unacceptable drift condition. If the heat exchanger 800 is operating in a dry mode where the liquid dispersion system 806 is off for a period of time because there are no evaporated liquid particles being carried in the airflow toward the air outlet 813 (e.g., the insulating pad 808 is dry), the controller 162 can determine that no drift is present.

[0098]

[0110] The drift measurement sensor 150 can be mounted at various locations on the heat exchanger 800 to monitor drift. Referring to FIG. 37B , the heat exchanger 800 includes a drift measurement sensor 150 mounted downstream of the insulation pad 808 and upstream of the indirect heat exchanger 804. The controller 162 can compare changes in air variables as air passes through the insulation pad 808. Furthermore, because the drift measurement sensor 150 is immediately downstream of the insulation pad 808, the drift measurement sensor 150 is positioned to detect drift from the insulation pad 808 as it contacts the finned tube heat exchanger 817. Positioning the drift measurement sensor 150 between the insulation pad 808 and the finned tube heat exchanger 817 also allows for a more accurate determination of the magnitude of the increase in drift. The controller 162 can be programmed to adjust the operation of the heat exchanger 800 to address unacceptable drift conditions and to limit fouling, scale, and / or corrosion.

[0099]

[0111] In some embodiments, the drift measurement sensor utilized in the heat exchange device can include a sensor configured to detect microorganisms instead of or in addition to conductivity measurements. Microorganisms can include, for example, fungi, algae, and bacteria. The sensor can detect, for example, specific microorganisms and / or total bacterial counts in a sample. The heat exchange device controller can use bacterial detection to determine the onset of drift containing undesirable microbial content, e.g., drift containing a microbial load above a predetermined threshold. The drift measurement sensor can be periodically cleaned using manual or automated techniques, such as chlorine injection, ultraviolet light treatment, and / or water rinsing. The drift measurement sensor can also be utilized to treat collected water before returning it to the unit's sump, such as by an in-line UV light treatment system to deactivate or kill detected bacteria after measurement.

[0100]

[0112] In some embodiments, the air contactor airflow generator includes an air contactor housing or other structure that generates the airflow, for example, a hyperboloid housing of a natural draft cooling tower that has a shape that cooperates with the heated rising air in the cooling tower to draw air into the cooling tower and direct the heated air upward and out of the cooling tower.

[0101]

[0113] As another example, some air contactors include nozzles that spray a liquid, causing air movement with the liquid spray. The air contactor has a housing or other structure that directs the moving air into an airflow through the air contactor. In some embodiments, the air contactor does not include a fan.

[0102]

[0114] 38 , a drift measurement sensor 900 is provided that includes a body such as a primary conduit 902 having an inlet 904 and an outlet 906 for receiving air. The drift measurement sensor 900 includes one or more sensors, such as a particulate matter sensor 908, a relative humidity sensor 910, and a temperature sensor 912, configured to detect relevant variables of the air traveling through the primary conduit 902. The drift measurement sensor 900 further includes a dehumidifier, such as a cooler 914, that removes water from the air and directs the collected water into a secondary conduit 916. The secondary conduit 916 has a collection portion, such as a U-shaped bend 918, for collecting water, and a bacteria sensor 920 for detecting one or more variables related to bacteria in the water within the bend 918.

[0103]

[0115] 39, another embodiment of the drift measurement sensor 900 is provided in which the drift measurement sensor 900 includes a conductivity sensor 922. In addition to a bacteria sensor 920 that detects one or more variables of bacteria in the water of the bend 918, the conductivity sensor 922 is configured to detect the conductivity of the water within the bend 918.

[0104]

[0116] Various other configurations of the drift measurement sensor 900 can be provided. For example, Figure 40 shows an embodiment of the drift measurement sensor 900 in which the drift measurement sensor 900 includes a bacteria sensor 920, but does not include a particulate matter sensor 908, a relative humidity sensor 910, or a temperature sensor 912. A conductivity sensor 922 has been added to the embodiment of Figure 41.

[0105]

[0117] 42, a drift measurement sensor 1000 is provided that includes a body 1002 having an inlet 1004 for receiving air, an outlet 1006, and a collection portion such as a bend 1008 that can collect airborne drift. The drift measurement sensor 1000 has a conduit 1010 that directs the collected drift to a bacteria sensor 1012. The drift measurement sensor 1000 further includes a particulate matter sensor 1014, a relative humidity sensor 1016, and a temperature sensor 1018. In another embodiment, the drift measurement sensor 1000 can include a conductivity sensor 1020 as shown in FIG.

[0106]

[0118] In yet another embodiment, as shown in Figure 44, the drift measurement sensor 1000 can be provided without the particulate matter sensor 1014, the relative humidity sensor 1016, and the temperature sensor 1018. Similarly, as shown in Figure 45, the drift measurement sensor can include a bacteria sensor 1012 and a conductivity sensor 1020.

[0107]

[0119] 46, there is provided a drift measurement sensor 1100 including a body 1102, an inlet opening 1104, an outlet 1106, and a fan assembly 1108 for generating airflow through the body 1102. The drift measurement sensor 1100 has a particulate matter sensor 1110, a relative humidity sensor 1112, and a temperature sensor 1114. The drift measurement sensor 1100 also has a dehumidifier such as a cooler 1116 that removes water from the air, and a conduit 1118 configured to direct the collected water to a bacteria sensor 1120. In another embodiment, as shown in FIG. 47, the drift measurement sensor 1100 has a conductivity sensor 1122.

[0108]

[0120] In yet another embodiment, as shown in Figure 48, a drift measurement sensor 1100 is provided without the particulate matter sensor 1110, the relative humidity sensor 1112, and the temperature sensor 1114. As shown in Figure 49, the drift measurement sensor 1100 can include a bacteria sensor 1120 and a conductivity sensor 1122.

[0109]

[0121] 50, a drift measurement sensor 1200 similar to the drift measurement sensor 600 of FIG. 35 is provided. The drift measurement sensor 1200 includes a body 1202 having an air inlet 1204, an outlet 1206, a fan assembly 1208, and a collector such as a bend 1210 for collecting water (e.g., drift) in the air traveling through the body 1202. The drift measurement sensor 1200 has a conduit 1212 that directs the collected water to a bacteria sensor 1214. The drift measurement sensor 1200 further includes a particulate matter sensor 1216, a relative humidity sensor 1218, and a temperature sensor 1220. In one embodiment, as shown in FIG. 51, the drift measurement sensor 1200 includes a conductivity sensor 1222.

[0110]

[0122] 52, the drift measurement sensor 1200 can be provided without the particulate matter sensor 1216, the relative humidity sensor 1218, and the temperature sensor 1220. As shown in FIG. 53, the drift measurement sensor 1200 can include a conductivity sensor 1222.

[0111]

[0123] Referring to Figure 54, another embodiment of a drift measurement sensor 150 is provided that is similar to the embodiment shown in Figure 11. One difference between the drift measurement sensors 150 of Figures 11 and 54 is that the drift measurement sensor 150 of Figure 54 has a damper 192 mounted at the outlet 176 but does not include a damper at the inlet 174.

[0112]

[0124] Referring to FIG. 55, another embodiment of a drift measurement sensor 150 is provided that is similar in many respects to the embodiment of FIG. 4, with the differences emphasized. In the embodiment of FIG. 55, the tube 170 of the drift measurement sensor 150 has a large diameter portion 170B, a small diameter portion 170B, and a neck portion 170C connecting the large diameter portion 170B and the small diameter portion 170B. The large diameter portion 170B includes an air inlet 174. The neck portion 170C directs air and drift from the large diameter portion 170B into the small diameter portion 170A. Sensors 152, 154, and 156 detect variables of the airflow (such as particulate matter, relative humidity, and temperature) within the small diameter portion 170A. The ratio of the diameters of the large diameter portion 170B and the small diameter portion 170A and the shape of the neck portion 170C can be selected so that the air flowing through the small diameter portion 170A has the same velocity as the airflow outside the tube 170.

[0113]

[0125] 56A-56E, exemplary charts similar to those of Figures 3A-3F described above are provided containing data illustrating how changing conditions in a cooling tower 100 can be used to detect changes in the drift rate of the cooling tower 100. The charts of Figures 56A-56E have additional columns for the spray rate 1302, drift volume 1304, and drift rate 1306 of the liquid dispersion system 106 of the cooling tower 100. The spray rate 1302 and drift volume 1304 may be in units of gallons per minute (gpm), and the drift rate 1306 is a dimensionless quantity, such as a percentage.

[0114]

[0126] The drift rate 1306 is calculated by dividing the drift volume 1304 by the spray flow rate 1302 and then multiplying by 100. In other words, the drift rate 1306 is the percentage of the spray from the liquid dispersion system 106 that exits the cooling tower 100 as drift. With reference to FIGS. 56A through 56C, the controller 162 can calculate the drift rate 1306 based on data collected by sensors in the cooling tower 100. The controller 162 can determine whether the drift rate 1306 of the cooling tower is normal or abnormal by comparing the change in the drift rate 1306 from a baseline condition to a new condition. For example, with reference to FIG. 56A, the controller 162 can determine an abnormal drift rate 1306 because the drift rate 1306 doubles, i.e., changes from 0.003% to 0.006%, when the cooling tower 100 changes from the baseline condition to new condition 2. The threshold change that triggers the determination of an abnormal drift condition can be fixed or variable, such as a 25% increase in drift rate given a particular change in the operating state of the cooling tower 100. In contrast, the controller 162 can determine a normal drift rate 1306 because the drift rate 1306 remains the same (0.003%) when the cooling tower 100 changes from the baseline state to new State 2.

[0115]

[0127] Alternatively or additionally, controller 162 may determine whether the drift rate is normal or abnormal by comparing drift rate 1306 for a given state to a threshold drift rate, such as 0.005%. For example, if drift rate 1306 for a given state is 0.005% or less, the drift change between the air inlet and air outlet of cooling tower 100 is normal. If drift rate 1306 for a state is greater than 0.005%, the drift change between the air inlet and air outlet of cooling tower 100 is abnormal.

[0116]

[0128] 56D , an exemplary chart 1320 is provided illustrating an evaluation of changes in spray rate of the liquid dispersion system 106. Changing from baseline state 1322 to new state 1324 and new state 1326, water spray rate 1328, 1330 increases. However, in new state 1326, the amount of PM2.5 and PM10 particulate matter 1332 at the air outlet 130 of the cooling tower 100 is greater than the amount of particulate matter 1334 at new state 1324. In new state 1324, there was no significant increase in drift rate 1336, as the increase in PM2.5 and PM10 particulate matter 1334 at the air outlet 130 can be attributed to the increase in spray rate 1328 of the liquid dispersion system 106. In new state 1326, the amount 1332 of particulate matter in air outlet 130 has increased significantly and / or disproportionately relative to the increase in spray rate 1330 of liquid dispersion system 106 (e.g., compared to the change in new state 1326). Controller 162 determines that the increase in particulate matter 1332 in air outlet 130 is the result of an abnormal increase in the drift rate of cooling tower 100 beyond an acceptable or expected drift rate for those states, because not all of the increase in particulate matter 1332 can be attributed to the increase in spray rate 1330 or any other monitored variable. Alternatively or additionally, controller 162 may calculate drift rate 1336 for each state and determine that the drift rate is abnormal or normal based on a comparison to a drift rate threshold.

[0117]

[0129] 56E, an exemplary chart 1350 is provided illustrating an evaluation of changes in fan assembly 102 speed and liquid dispersion system 106 spray rate. When changing from baseline condition 1352 to new condition 1354 or new condition 1355, fan assembly 102 speed 1356, 1358 increases by 25%, and water spray rate 1360, 1362 increases. However, in new condition 1355, the amount of PM2.5 and PM10 particulate matter 1364 at the air outlet 130 of the cooling tower 100 is significantly higher (e.g., nearly three times higher) than the amount of particulate matter 1366 at new condition 1354. In new condition 1354, drift rate 1368 increased by a normal amount because the increase in PM2.5 and PM10 particulate matter 1366 at the air outlet 130 can be attributed to the increased liquid dispersion system 106 spray rate 1360 and increased fan assembly 102 speed. Under new condition 1355, the amount of particulate matter 1364 in air outlet 130 has increased significantly and / or disproportionately (e.g., compared to the change under new condition 1354) relative to the increase in spray rate 1362 of liquid dispersion system 106 and the increase in speed 1358 of fan assembly 102. Controller 162 determines that the increase in particulate matter 1364 in air outlet 130 is the result of an abnormal increase in the drift rate of cooling tower 100 beyond an acceptable or expected drift rate under these conditions, because not all of the increase in particulate matter 1364 can be attributed to the increase in spray rate 1362, the increase in fan speed 1358, or any other monitored variable.

[0118]

[0130] The use of singular terms such as "a," "an," etc. is intended to cover both the singular and the plural unless otherwise indicated herein or clearly contradicted by context. The terms "comprising," "having," "including," and "containing" are to be construed as open-ended terms. As used herein, the phrase "at least one of" is intended to be construed in a disjunctive sense. For example, the phrase "at least one of A and B" is intended to encompass A, B, or both A and B.

[0119]

[0131] While particular embodiments of the present invention have been shown and described, it will be appreciated that numerous modifications and variations will occur to those skilled in the art, and it is intended that the present invention cover all such modifications and variations that fall within the scope of the appended claims. For example, it will be appreciated that the present disclosure is applicable to other processes, such as manufacturing processes that spray water or other liquids.

Claims

1. An air contactor comprising: an airflow generator for generating an airflow; a liquid dispersion system operable to disperse liquid contacted by said air stream; a sensor configured to detect an air variable of the airflow; a controller operatively connected to the liquid dispersion system and the sensor, determining an operating variable of at least one of the airflow generator and the liquid dispersion system; a controller configured to determine a drift state of the air contactor based at least in part on the air variables of the air flow and the operating variables of the at least one of the air flow generator and the liquid distribution system; An air contactor comprising:

2. the drift condition includes an abnormal drift condition of the air contactor; The controller the air variables are sufficiently different from expected air variables; and / or the operating variable is sufficiently different from the expected operating variable; 2. The air contactor of claim 1, configured to determine the abnormal drift condition in response to:

3. The air contactor of claim 1 , wherein the drift condition comprises a drift rate of the air contactor.

4. the drift condition includes an abnormal drift condition of the air contactor; the controller is configured to determine a drift rate of the air contactor; 2. The air contactor of claim 1, wherein the controller is configured to determine the abnormal drift condition in response to the drift rate of the air contactor being an abnormal drift rate.

5. The air contactor of claim 1 , wherein the drift condition comprises an abnormal change in the drift of the air contactor.

6. the air variables include an upstream air variable and a downstream air variable; The sensor an upstream sensor configured to detect the upstream air variable of the air flow upstream of the air flow in contact with the liquid; a downstream sensor configured to detect the downstream air variable of the air flow downstream of the air flow in contact with the liquid; 10. The air contactor of claim 1, comprising:

7. the drift condition includes an abnormal drift condition, The air contactor of claim 6 , wherein the controller is configured to determine the drift condition based at least in part on the downstream air variable being abnormal relative to the upstream air variable.

8. the air variables include a first air variable associated with a first operating state of the air contactor and a second air variable associated with a second operating state of the air contactor; the operating variables include a first operating variable associated with the first operating state and a second operating variable associated with the second operating state; the drift condition includes an abnormal drift condition, The controller the second air variable has changed abnormally from the first air variable; and / or the second operating variable has changed abnormally from the first operating variable; 2. The air contactor of claim 1, configured to determine the abnormal drift condition of the air contactor in response to:

9. the airflow generator includes a fan assembly; the first operating state includes the controller being configured to control the liquid distribution system to operate the fan assembly at a first speed and distribute a liquid; 9. The air contactor of claim 8, wherein the second operating condition includes the controller being configured to control the liquid distribution system to operate the fan assembly at a second different speed and distribute liquid.

10. the drift state is an abnormal drift state, 2. The air contactor of claim 1, wherein the controller is configured to determine the abnormal drift condition based at least in part on comparing the air variables and the operating variables to a data set of variables corresponding to normal drift conditions.

11. the operating variables include variables of the liquid; The air contactor of claim 1 , wherein the controller is configured to determine the drift condition based at least in part on the air variable and the variable of the liquid.

12. The air contactor of claim 1 , wherein the controller is configured to determine the drift state using a machine learning algorithm to process the air variables and the operating variables.

13. 2. The air contactor of claim 1, wherein the operating variables of at least one of the air flow generator and the liquid distribution system include a first variable of the air flow generator and a second variable of the liquid distribution system.

14. the airflow generator including a fan assembly operable to generate the airflow; The air contactor of claim 1 , wherein the operating variables include fan assembly operating variables.

15. the air sensor includes a particulate matter sensor; The air contactor of claim 1 , wherein the air variables include a particulate variable indicative of particulate matter in the airflow.

16. The particulate matter sensor comprises: a first particulate matter sensor configured to detect particles of a first size; a second particulate matter sensor configured to detect particles of a second smaller size; The particulate variable is a first particulate variable indicative of particulate matter in the airflow having the first size; a second particulate variable indicative of particulate matter in the airflow having the second size; and 16. The air contactor of claim 15, comprising:

17. the sensors include a particulate matter sensor, a relative humidity sensor, and a temperature sensor; The air contactor of claim 1 , wherein the air variables include a particulate matter variable, a relative humidity variable, and an air temperature variable.

18. the airflow generator includes a fan assembly; The operating variables of at least one of the airflow generator and the liquid dispersion system are: a fan speed of the fan assembly; and an operating state of the liquid dispersion system; and 10. The air contactor of claim 1, comprising:

19. The operating variables of at least one of the airflow generator and the liquid dispersion system are: an operating state of the liquid dispersion system; and a variable of the liquid; 10. The air contactor of claim 1, comprising:

20. The sensor a passageway for receiving a portion of the airflow; a particulate sensor for detecting a particulate variable of the portion of the airflow; 10. The air contactor of claim 1, comprising:

21. The sensor a passageway for receiving a portion of the airflow; an airflow sensor for detecting the air variable of the portion of the airflow in the passage; a heater, a cooler, or both, in the passageway upstream of the airflow sensor; 10. The air contactor of claim 1, comprising:

22. 2. The air contactor of claim 1, wherein the controller is configured to adjust operation of at least one of the air flow generator and the liquid distribution system in response to the determination of the drift condition.

23. further comprising a pad, fill, and / or indirect heat exchanger; 10. The air contactor of claim 1, wherein the liquid distribution system is operable to distribute the liquid over the pad, fill, and / or indirect heat exchanger.

24. 10. The air contactor of claim 1, wherein the liquid is an air pollutant capture solution.

25. the air contactor is a hyperbolic cooling tower; the airflow generator is the outer shell of the hyperbolic cooling tower; 2. The air contactor of claim 1, wherein the operating variable is an operating variable of the liquid dispersion system.

26. the operating variables of at least one of the air generator and the liquid distribution system include a plurality of variables of the liquid distribution system; The plurality of variables are: a first variable indicating whether a pump of the liquid dispersion system is operating; a second variable indicative of the conductivity of the liquid; 10. The air contactor of claim 1, comprising:

27. 1. A method of operating an air contactor having an air flow generator that generates an air flow, comprising: operating a liquid dispersion system of the air contactor to disperse liquid in contact with the air flow; detecting an air variable of the air flow with a sensor of the air contactor; determining an operating variable of at least one of the airflow generator and the liquid dispersion system; determining a drift state of the air contactor based at least in part on the air variables of the air flow and the operating variables of the at least one of the air flow generator and the liquid distribution system; A method comprising:

28. the airflow generator includes a fan assembly; 28. The method of claim 27, further comprising operating the fan assembly to generate the air flow from an air inlet to an air outlet of the air contactor.

29. 28. The method of claim 27, wherein the drift condition of the air contactor is an abnormal drift condition, a drift rate of the air contactor, or an abnormal change in drift of the air contactor.

30. the air variables include an upstream air variable and a downstream air variable; the sensors of the air contactor include an upstream sensor and a downstream sensor; Detecting the air variable of the air flow comprises: detecting, with the upstream sensor, the upstream air variable of the air flow upstream of the air flow contacting the liquid; detecting, with the downstream sensor, the downstream air variable of the air stream downstream of the air stream contacting the liquid; 28. The method of claim 27, comprising:

31. the drift state is an abnormal drift state, 31. The method of claim 30, wherein determining the abnormal drift condition comprises determining the drift condition based at least in part on the downstream air variable being abnormal relative to the upstream air variable.

32. the air variables include a first air variable associated with a first operating state of the air contactor and a second air variable associated with a second operating state of the air contactor; the operating variables include a first operating variable associated with the first operating state and a second operating variable associated with the second operating state; the drift condition includes an abnormal drift condition, Determining the abnormal drift condition of the air contactor comprises: an abnormal change in the first air variable relative to the second air variable; and / or an abnormal change in the first operating variable relative to the second operating variable; 28. The method of claim 27, based at least in part on

33. the drift condition includes an abnormal drift condition, 28. The method of claim 27, wherein determining the abnormal drift condition comprises comparing the air variables and the operational variables to a data set of variables corresponding to normal drift conditions.

34. 28. The method of claim 27, wherein determining the drift condition includes using a machine learning algorithm to process the air variables and the operational variables.

35. 28. The method of claim 27, wherein the operating variables of at least one of the air flow generator and the liquid distribution system include a first variable of the air flow generator and a second variable of the liquid distribution system.

36. 28. The method of claim 27, wherein the air variables include particulate variables indicative of particulate matter in the airflow.

37. 37. The method of claim 36, wherein the air variables further include a relative humidity variable and a temperature variable.

38. Detecting the air variable of the air flow comprises: operating a fan of the sensor to direct a portion of the airflow into a passageway of the sensor; heating, cooling, or both heating and cooling at least a portion of the air flow; detecting the air variable of the portion of the air flow; 28. The method of claim 27, comprising:

39. operating the liquid distribution system of the air contactor comprises: liquid-absorbent material, Phil, and indirect heat exchanger, 28. The method of claim 27, comprising dispersing the liquid onto at least one of:

40. 1. An apparatus for detecting drift in an air flow of an air contactor, the air flow having a first velocity within the air contactor, the apparatus comprising: an inlet for receiving a portion of the air flow; The exit and an airflow generator configured to cause the portion of the airflow to have a second velocity corresponding to the first velocity of the airflow in the air contactor as the portion of the airflow travels between the inlet and the outlet; a sensor operable to detect an air variable of the portion of the air flow as the portion of the air flow travels at the second velocity; An apparatus comprising:

41. 41. The apparatus of claim 40, wherein the airflow generator includes a fan assembly operable to cause the portion of the airflow to have the second velocity.

42. the airflow generator includes a secondary fan assembly; The apparatus further includes a controller operably coupled to the secondary fan assembly; the controller is configured to receive an operating variable of a primary fan assembly of the air contactor; 41. The apparatus of claim 40, wherein the controller is configured to control the secondary fan assembly based at least in part on the operating variable of the primary fan assembly of the air contactor.

43. 43. The apparatus of claim 42, wherein the operating variables include a fan speed of the primary fan assembly of the air contactor.

44. the airflow generator includes a passageway including the inlet and the outlet; 41. The apparatus of claim 40, wherein the passage is configured such that the portion of the air flow has the second velocity in response to the inlet receiving the portion of the air flow at the first velocity.

45. 41. The apparatus of claim 40, wherein the airflow generator includes a louver operable to cause the portion of the airflow to have the second velocity as the portion of the airflow travels between the inlet and the outlet.

46. 41. The apparatus of claim 40, wherein the sensor comprises a particulate matter sensor.

47. 41. The apparatus of claim 40, wherein the airflow generator is configured such that the portion of the airflow has the second velocity that is the same as the first velocity of the airflow in the air contactor.

48. the airflow generator includes a passageway; 41. The apparatus of claim 40, wherein the airflow generator further includes a heater, a cooler, or both in the passageway upstream of a sensor.

49. 41. The apparatus of claim 40, wherein the airflow generator includes a passageway having straight and bent portions.

50. 41. The apparatus of claim 40, further comprising a dehumidifier upstream of the sensor operable to dehumidify the portion of the air flow traveling from the air inlet to the air outlet.

51. The sensor a first particulate matter sensor configured to detect particles of a first size; a second particulate matter sensor configured to detect particles of a second smaller size; The air variables are: a first particulate variable indicative of particulate matter in the airflow having the first size; a second particulate variable indicative of particulate matter in the airflow having the second size; and 41. The apparatus of claim 40, comprising:

52. The sensor Particulate matter sensors, relative humidity sensor, temperature sensors, Bacteria sensors, Carbon monoxide sensor, carbon dioxide sensor, a volatile organic compound sensor, or Combinations of these, 41. The apparatus of claim 40, comprising:

53. 41. The apparatus of claim 40, wherein the airflow generator includes a passageway having a collector configured to collect liquid separated from the portion of the airflow.

54. 54. The apparatus of claim 53, wherein the sensor includes a sensor for detecting a variable of the liquid.

55. 41. The apparatus of claim 40, wherein the air inlet includes a filter.

56. 1. A method for detecting drift in an air contactor air flow, comprising: determining a variable representing a first velocity of the air flow in the air contactor; controlling the drift detection device such that a portion of the airflow entering the drift detection device at the first velocity travels through a passageway of the drift detection device at a second velocity corresponding to the first velocity; detecting an air variable of the portion of the air flow with a sensor as the portion of the air flow travels through the passage at the second velocity; A method comprising:

57. 57. The method of claim 56, wherein determining the variable representative of the first velocity of the airflow comprises determining a speed of a fan assembly of the air contactor.

58. 57. The method of claim 56, wherein determining the variable representative of the first velocity of the airflow comprises detecting the first velocity of the airflow with an air velocity sensor.

59. 57. The method of claim 56, wherein controlling the drift detection device includes operating a fan of the drift detection device to cause the airflow to travel through the passage at the second velocity.

60. 57. The method of claim 56, wherein controlling the drift detection device includes selectively opening at least one of an inlet and an outlet of the passageway such that the portion of the airflow travels through the passageway at the second velocity.

61. 57. The method of claim 56, wherein detecting the air variable of the portion of the airflow comprises detecting particulate matter in the airflow.

62. 57. The method of claim 56, further comprising dehumidifying the portion of the airflow upstream of the sensor.

63. further comprising separating a liquid from the portion of the air stream; 57. The method of claim 56, wherein sensing the air variable comprises sensing a variable of the liquid separated from the portion of the air stream.

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