Patent Application
20240344720
The present application relates to a refrigeration system with an evaporative cooling device.
Refrigeration systems are often used to provide cooling to temperature-controlled display devices (e.g., cases, merchandisers, etc.) in supermarkets and other similar facilities. Vapor compression refrigeration systems are a type of refrigeration system that provide such cooling by circulating a fluid refrigerant (e.g., a liquid and/or vapor) through a thermodynamic vapor compression cycle. In a vapor compression cycle, the refrigerant is typically (1) compressed to a high temperature/pressure state (e.g., by a compressor of the refrigeration system), (2) cooled/condensed to a lower temperature state (e.g., in a gas cooler or condenser which absorbs heat from the refrigerant), (3) expanded to a lower pressure (e.g., through an expansion valve), and (4) evaporated to provide cooling by absorbing heat into the refrigerant.
This disclosure describes methods and systems for recirculating a liquid in an evaporative cooling device. The evaporative cooling device can be, for example, a gas cooler in a CO2 refrigeration system.
In an example implementation, a cooling system includes one or more heat exchanger coils; one or more evaporative pads external to the one or more heat exchanger coils; one or more nozzle assemblies external to the one or more evaporative pads, the one or more nozzle assemblies being coupled to a supply of liquid and configured to provide the liquid to at least one of the one or more evaporative pads; a basin configured to collect a portion of liquid from the one or more evaporative pads; and an injector disposed between the supply of liquid and the one or more nozzle assemblies. The injector includes a first inlet coupled to the supply of liquid, a second inlet coupled to the basin, and an outlet coupled to the one or more nozzle assemblies.
In an aspect combinable with the example implementation, the injector includes a venturi coupled to the first and second inlets and the outlet.
In another aspect combinable with any of the previous aspects, the venturi is configured to receive a flow of liquid through the first inlet; draw in a fluid through the second inlet; form a mixture of the liquid from the first inlet and the fluid from the second inlet; and discharge the mixture through the outlet of the injector.
In another aspect combinable with any of the previous aspects, the injector is configured to draw air from the basin.
In another aspect combinable with any of the previous aspects, the one or more nozzle assemblies includes one or more electrostatic spray nozzles.
In another aspect combinable with any of the previous aspects, the one or more electrostatic spray nozzles is configured to distribute the liquid with an electrostatic charge to the one or more evaporative pads.
In another aspect combinable with any of the previous aspects, the one or more nozzle assemblies includes one or more drip nozzles, misting nozzles, drip emitters, or drip headers.
Another aspect combinable with any of the previous aspects further includes a controller communicably coupled to a flow control valve coupled to the first inlet of the injector.
In another aspect combinable with any of the previous aspects, the controller is configured to perform operations including operating the flow control valve to control a flow rate of the supply of liquid to the injector.
Another aspect combinable with any of the previous aspects further includes a flow meter communicably coupled to the controller and configured to measure a flow rate of the liquid downstream of the injector.
In another aspect combinable with any of the previous aspects, the controller is configured to perform operations including operating the flow control valve to adjust the flow rate of the supply of liquid based at least in part on the measured flow rate of the liquid.
In another aspect combinable with any of the previous aspects, the controller is configured to perform operations including operating the flow control valve to adjust the flow rate of the supply of liquid to be less than the measured flow rate.
In another aspect combinable with any of the previous aspects, the controller is configured to perform operations including adjusting a flow rate of the supply of liquid based at least in part on an expected rate of evaporation of the liquid from the one or more evaporative pads.
Another aspect combinable with any of the previous aspects further includes a check valve coupled between the basin and the second inlet and configured to prevent the supply of liquid from flowing into the basin through the second inlet.
Another aspect combinable with any of the previous aspects further includes a filter coupled between the basin and the second inlet of the injector.
In another aspect combinable with any of the previous aspects, the filter includes a calcium filter.
In another example implementation, a method of operating a cooling system includes operating a cooling system that includes one or more heat exchanger coils, one or more evaporative pads external to the one or more heat exchanger coils, one or more nozzle assemblies external to the one or more evaporative pads, a basin positioned adjacent the one or more evaporative pads, and an injector disposed between a supply of a first fluid and the one or more nozzle assemblies. The injector includes a first inlet coupled to the supply of the first fluid, a second inlet coupled to the basin, and an outlet coupled to the one or more nozzle assemblies. The method further includes providing a liquid from the one or more nozzle assemblies to at least one of the one or more evaporative pads; collecting at least a portion of the liquid from at least one of the one or more evaporative pads in the basin; providing a flow of the first fluid into the first inlet of the injector; drawing a second fluid from the basin into the second inlet; and discharging a mixture of the first fluid and the second fluid as the liquid through an outlet of the injector to the one or more nozzle assemblies.
In an aspect combinable with the example implementation, the first fluid includes air, and the second fluid includes water.
In another aspect combinable with any of the previous aspects, the first fluid includes water.
In another aspect combinable with any of the previous aspects, the one or more nozzle assemblies include drip nozzles, and the method further includes distributing the liquid to the one or more evaporative pads through the drip nozzles of the one or more nozzle assemblies.
In another aspect combinable with any of the previous aspects, the one or more nozzle assemblies include electrostatic spray nozzles.
Another aspect combinable with any of the previous aspects further includes distributing the liquid with an electrostatic charge to the one or more evaporative pads.
Another aspect combinable with any of the previous aspects further includes controlling a flow of the first fluid into the first inlet of the injector using a flow control valve communicably coupled to a controller.
In another example implementation, a liquid injection assembly for an adiabatic gas cooling system includes one or more nozzle assemblies external to one or more evaporative pads, the one or more nozzle assemblies configured to provide a liquid to at least one of the one or more evaporative pads; a basin configured to collect a portion of liquid from the one or more evaporative pads; and an eductor disposed between a supply of a first fluid and the one or more nozzle assemblies. The eductor includes a first inlet coupled to the supply of the first fluid, a second inlet coupled to the basin, and an outlet coupled to the one or more nozzle assemblies.
In an aspect combinable with the example implementation, the eductor includes a venturi coupled to the first and second inlets and the outlet, the venturi configured to receive a flow of the first fluid through the first inlet; draw in a second fluid through the second inlet; form a mixture of the first fluid and the second fluid; and discharge the mixture through the outlet of the eductor.
In another aspect combinable with any of the previous aspects, the eductor is configured to draw air from the basin.
In another aspect combinable with any of the previous aspects, the one or more nozzle assemblies include one or more electrostatic spray nozzles.
In another aspect combinable with any of the previous aspects, the one or more electrostatic spray nozzles is configured to distribute the liquid with an electrostatic charge to the one or more evaporative pads.
In another aspect combinable with any of the previous aspects, the one or more nozzle assemblies include one or more drip nozzles.
Another aspect combinable with any of the previous aspects further includes a check valve coupled between the basin and the second inlet and configured to prevent the first fluid from flowing into the basin through the second inlet.
Another aspect combinable with any of the previous aspects, further includes a filter coupled between the basin and the second inlet of the eductor.
In another aspect combinable with any of the previous aspects, the filter includes a calcium filter.
Particular implementations of the subject matter described in this specification can be implemented to realize one or more of the following advantages. The injector recirculates liquid in a passive manner without electricity or a pump. The injector can draw air thought the second inlet in the absence of a liquid eliminating a need to maintain a liquid level in the basin. The injector can reduce maintenance and repair costs as compared with a pump.
The details of one or more implementations of the subject matter described in this specification are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages of the subject matter will become apparent from the description, the drawings, and the claims.
Providing a target, such as a temperature-controlled case, with cooling is often performed in order to store products, such as refrigerated goods or frozen goods, in the target. In some applications, the target is cooled by a cooling system that circulates a refrigerant through a circuit path and includes a gas cooler for cooling or condensing a high-temperature refrigerant. The gas cooler can include heat exchanger coils and moisture pads. The moisture pads can be wetted with a device that drips water down through the moisture pads.
In some situations, the cooling systems generate excess liquid such as water and runoff from the moisture pads that can be drained or recirculated back to drip-emitters at the top of the moisture pads. For example, the water flowing through the moisture pads may not be completely absorbed by the moisture pads or evaporated by the airflow drawn through the pads. As a result, the amount of water necessary for the moisture pads to be adequately wetted and able to provide sufficient cooling can require excess water to flow through the moisture pads. In another situation, spraying water droplets on the moisture pads can cause water to “blow-through” the moisture pad, which decreases efficiency and creates excess runoff, which can result in coil saturation, which leads to formation of scale, corrosion materials, etc.
Implementations described herein are related to a cooling device for a refrigeration system. The cooling device includes a liquid supply line feeding electrostatic spray nozzles that atomize the liquid droplets and electrostatically charge the droplets. Electrostatically charging the droplets can provide improved moisture pad coverage and liquid retention on the moisture pads, as the droplets are capable of being attracted to oppositely charged moisture pads.
A refrigeration system including an adiabatic gas cooler according to the present disclosure is shown by way of examples as a CO2 refrigeration system and components thereof. according to various exemplary implementations. The CO2 refrigeration system can be a vapor compression refrigeration system that uses primarily carbon dioxide (i.e., CO2) as a refrigerant. In some implementations, the CO2 refrigeration system can be used to provide cooling for temperature-controlled display devices in a supermarket or other similar facility. The CO2 refrigeration system can include a CO2 refrigerant circuit. The CO2 refrigerant circuit can include evaporators, low-temperature (LT) and medium-temperature (MT) compressors, gas coolers, a receiver, and expansion valves. The CO2 refrigerant circuit can be configured to circulate CO2 as a refrigerant to provide cooling to the evaporators.
In some implementations, the CO2 refrigeration system includes a receiving tank (e.g., a flash tank, a refrigerant reservoir, etc.) containing a mixture of CO2 liquid and CO2 vapor, and a gas bypass valve. The gas bypass valve can be arranged in series with one or more MT compressors of the CO2 refrigeration system. The gas bypass valve provides a mechanism for controlling the CO2 refrigerant pressure within the receiving tank by venting excess CO2 vapor to the suction side of the CO2 refrigeration system MT compressors.
The CO2 refrigeration system includes a controller for monitoring and controlling the pressure, temperature, and/or flow of the CO2 refrigerant throughout the CO2 refrigeration system. The controller can operate the gas bypass valve (e.g., according to the various control processes described herein) to efficiently regulate the pressure of the CO2 refrigerant within the receiving tank. Additionally, the controller can interface with other instrumentation associated with the CO2 refrigeration system (e.g., measurement devices, timing devices, pressure sensors, temperature sensors, etc.). The controller can provide appropriate control signals to a variety of operable components of the CO2 refrigeration system (e.g., compressors, valves, power supplies, flow diverters, etc.) to regulate the pressure, temperature, and/or flow at other locations within the CO2 refrigeration system. Advantageously, the controller can be used to facilitate efficient operation of the CO2 refrigeration system, reduce energy consumption, and improve system performance.
Gas cooler/condenser 2 can be a heat exchanger, fan-coil unit, or other similar device for removing heat from the CO2 refrigerant. According to other implementations that can use different refrigerants, the gas cooler/condenser can be a fluid cooler or condensing unit. Gas cooler/condenser 2 is shown receiving CO2 vapor from fluid conduit 1. In some implementations, the CO2 vapor in fluid conduit 1 can have a pressure within a range from approximately 45 bar to approximately 100 bar (i.e., about 640 psig to about 1420 psig), depending on ambient temperature and other operating conditions. In some implementations, gas cooler/condenser 2 can partially or fully condense CO2 vapor into liquid CO2 (e.g., if system operation is in a subcritical region). The condensation process can result in fully saturated CO2 liquid or a liquid-vapor mixture (e.g., having a thermodynamic quality between 0 and 1). In other implementations, gas cooler/condenser 2 can cool the CO2 vapor (e.g., by removing superheat) without condensing the CO2 vapor into CO2 liquid (e.g., if system operation is in a supercritical region). In some implementations, the cooling/condensation process is an isobaric process. Gas cooler/condenser 2 is shown outputting the cooled and/or condensed CO2 refrigerant into fluid conduit 3. The gas cooler/condenser 2 can include the evaporative gas cooler described herein.
High-pressure valve 4 receives the cooled and/or condensed CO2 refrigerant from fluid conduit 3 and outputs the CO2 refrigerant to fluid conduit 5. High-pressure valve 4 can control the pressure of the CO2 refrigerant in gas cooler/condenser 2 by controlling an amount of CO2 refrigerant permitted to pass through high-pressure valve 4. In some implementations, high-pressure valve 4 is a high-pressure thermal expansion valve (e.g., if the pressure in fluid conduit 3 is greater than the pressure in fluid conduit 5). In such implementations, high-pressure valve 4 can allow the CO2 refrigerant to expand to a lower pressure state. The expansion process can be an isenthalpic and/or adiabatic expansion process, resulting in a flash evaporation of the high-pressure CO2 refrigerant to a lower pressure, lower temperature state. The expansion process can produce a liquid/vapor mixture (e.g., having a thermodynamic quality between 0 and 1). In some implementations, the CO2 refrigerant expands to a pressure of approximately 38 bar (e.g., about 540 psig), which corresponds to a temperature of approximately 37° F. The CO2 refrigerant then flows from fluid conduit 5 into receiving tank 6.
Receiving tank 6 (e.g., receiver, receiver tank, etc.) collects the CO2 refrigerant from fluid conduit 5. In some implementations, receiving tank 6 can be a flash tank or other fluid reservoir. Receiving tank 6 includes a CO2 liquid portion and a CO2 vapor portion and can contain a partially saturated mixture of CO2 liquid and CO2 vapor. In some implementations, receiving tank 6 separates the CO2 liquid from the CO2 vapor. The CO2 liquid can exit receiving tank 6 through fluid conduits 9. Fluid conduits 9 can be liquid headers leading to either MT system portion 10 or LT system portion 20. The CO2 vapor can exit receiving tank 6 through fluid conduit 7. Fluid conduit 7 is shown leading the CO2 vapor to gas bypass valve 8.
Gas bypass valve 8 is shown receiving the CO2 vapor from fluid conduit 7 and outputting the CO2 refrigerant to MT system portion 10. In some implementations, gas bypass valve 8 can be operated to regulate or control the pressure within receiving tank 6 (e.g., by adjusting an amount of CO2 refrigerant permitted to pass through gas bypass valve 8). For example, gas bypass valve 8 can be adjusted (e.g., variably opened or closed) to adjust the mass flow rate, volume flow rate, or other flow rates of the CO2 refrigerant through gas bypass valve 8. Gas bypass valve 8 can be opened and closed (e.g., manually, automatically, by a controller, etc.) as needed to regulate the pressure within receiving tank 6.
In some implementations, gas bypass valve 8 includes a sensor for measuring a flow rate (e.g., mass flow, volume flow, etc.) of the CO2 refrigerant through gas bypass valve 8. In other implementations, gas bypass valve 8 includes an indicator (e.g., a gauge, a dial, etc.) from which the position of gas bypass valve 8 can be determined. This position can be used to determine the flow rate of CO2 refrigerant through gas bypass valve 8, as such quantities can be proportional or otherwise related.
In some implementations, gas bypass valve 8 can be a thermal expansion valve (e.g., if the pressure on the downstream side of gas bypass valve 8 is lower than the pressure in fluid conduit 7). According to one implementation, the pressure within receiving tank 6 is regulated by gas bypass valve 8 to a pressure of approximately 38 bar, which corresponds to about 37° F. This pressure/temperature state (i.e., approximately 38 bar, approximately 37° F.) can facilitate the use of copper tubing/piping for the downstream CO2 lines of the system. Additionally, this pressure/temperature state can allow such copper tubing to operate in a substantially frost-free manner.
Still referring to
MT evaporators 12 are shown receiving the cooled and expanded CO2 refrigerant from expansion valves 11. In some implementations, MT evaporators can be associated with display cases/devices (e.g., if CO2 refrigeration system 100 is implemented in a supermarket setting). MT evaporators 12 can be configured to facilitate the transfer of heat from the display cases/devices into the CO2 refrigerant. The added heat can cause the CO2 refrigerant to evaporate partially or completely. According to one implementation, the CO2 refrigerant is fully evaporated in MT evaporators 12. In some implementations, the evaporation process can be an isobaric process. MT evaporators 12 are shown outputting the CO2 refrigerant via fluid conduits 13, leading to MT compressors 14.
MT compressors 14 compress the CO2 refrigerant into a superheated vapor having a pressure within a range of approximately 45 bar to approximately 100 bar. The output pressure from MT compressors 14 can vary depending on ambient temperature and other operating conditions. In some implementations, MT compressors 14 operate in a transcritical mode. In operation, the CO2 discharge gas exits MT compressors 14 and flows through fluid conduit 1 into gas cooler/condenser 2.
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Expansion valves 21 can be electronic expansion valves or other similar expansion valves. Expansion valves 21 are shown receiving liquid CO2 refrigerant from fluid conduit 9 and outputting the CO2 refrigerant to LT evaporators 22. Expansion valves 21 can cause the CO2 refrigerant to undergo a rapid drop in pressure, thereby expanding the CO2 refrigerant to a lower pressure, lower temperature state. The expansion process can be an isenthalpic and/or adiabatic expansion process. In some implementations, expansion valves 21 can expand the CO2 refrigerant to a lower pressure than expansion valves 11, thereby resulting in a lower temperature CO2 refrigerant. Accordingly, LT system portion 20 can be used in conjunction with a freezer system or other lower temperature display cases.
LT evaporators 22 are shown receiving the cooled and expanded CO2 refrigerant from expansion valves 21. In some implementations, LT evaporators can be associated with display cases/devices (e.g., if CO2 refrigeration system 100 is implemented in a supermarket setting). LT evaporators 22 can be configured to facilitate the transfer of heat from the display cases/devices into the CO2 refrigerant. The added heat can cause the CO2 refrigerant to evaporate partially or completely. In some implementations, the evaporation process can be an isobaric process. LT evaporators 22 are shown outputting the CO2 refrigerant via fluid conduit 23, leading to LT compressors 24.
LT compressors 24 compress the CO2 refrigerant. In some implementations, LT compressors 24 can compress the CO2 refrigerant to a pressure of approximately 30 bar (e.g., about 425 psig) having a saturation temperature of approximately 23° F. (e.g., about −5° C.). LT compressors 24 are shown outputting the CO2 refrigerant through fluid conduit 25. Fluid conduit 25 can be fluidly connected with the suction (e.g., upstream) side of MT compressors 14.
In some implementations, the CO2 vapor that is bypassed through gas bypass valve 8 is mixed with the CO2 refrigerant gas exiting MT evaporators 12 (e.g., via fluid conduit 13). The bypassed CO2 vapor can also mix with the discharge CO2 refrigerant gas exiting LT compressors 24 (e.g., via fluid conduit 25). The combined CO2 refrigerant gas can be provided to the suction side of MT compressors 14.
To enhance the cooling efficiency of heat exchanger coils 202, the gas cooler 200 (or, in some systems, a condenser) can include one or more moisture panels such as a first moisture panel 204 and a second moisture panel 206. The first moisture panel 204 can be disposed external to the heat exchanger coils 202. The first moisture panel 204 man include one or more evaporative pads. The evaporative pads can be an adiabatic pad. The first moisture panel 204 can be used to generate pre-cooled air by an evaporative cooling process. For example, ambient air can pass through the first moisture panel 204 before the ambient air passes through the heat exchanger coils 202. As the ambient air passes through the first moisture panel 204, the ambient air cools as the moisture in the first moisture panel 204 evaporates and becomes pre-cooled air. The gas cooler 200 can include one or more moisture pads adjacent to the one or more cooling coils. For example, a plurality of moisture pads can be disposed adjacent to a plurality of cooling coils. According to the illustrated implementation of
In addition, the gas cooler 200 can include a second moisture panel 206 (e.g., second adiabatic panel, second adiabatic pad, second adiabatic moisture pad, second moisture pad, second cooling pad, etc.) disposed external to the heat exchanger coils 202. The second moisture panel 206 can be used to generate pre-cooled air by an evaporative cooling process. For example, ambient air can pass through the second moisture panel 206 before the ambient air passes through the heat exchanger coils 202. As the ambient air passes through the second moisture panel 206, the ambient air cools as the moisture in the second moisture panel 206 evaporates and becomes pre-cooled air. According to the illustrated implementation of
The second moisture panel 206 can be separated from the first moisture panel 204 by a distance 208. For example, the first moisture panel 204 can be separated from the second moisture panel 206 by a distance 208 at a base of the first moisture panel 204 and a base of the second moisture panel 206. The first moisture panel 204 can be separated from the second moisture panel 206 by a distance 208 at a center of the first moisture panel 204 and a center of the second moisture panel 206. The first moisture panel 204 can be separated from the second moisture panel 206 by a distance 208 at a top of the first moisture panel 204 and a top of the second moisture panel 206.
Gas cooler 200 can include an injector assembly, as will be discussed in more detail in relation to
The gas cooler 200 can also include one or more fans 210. The fans 210 draw ambient air or pre-cooled air through the heat exchanger coils 202, thereby cooling and condensing the refrigerant and providing cooling to the CO2 refrigeration system 100. The gas cooler 200 can include one or more motors that power the fans 210. The fans 210 draw air through moisture panels and subsequently through the heat exchanger coils 202. The fans 210 are shown located above the heat exchanger coils 202. The first moisture panel 204 can provide an evaporative cooling effect to the heat exchanger coil 202 when air is drawn through the first moisture panel 204 by the fans 210. The second moisture panel 206 can provide an evaporative cooling effect to the heat exchanger coil 202 when air is drawn through the second moisture panel 206 by the fans 210.
Gas cooler unit 302 includes a first nozzle array 308 (e.g., first water spray nozzle array, one or more spray nozzles, etc.). The first nozzle array 308 can be disposed external to the first moisture panel 204. For example, the first nozzle array 308 can be located on the exterior of the first moisture panel 204. In some implementations, the first nozzle array 308 can be configured to provide an atomized spray of electrostatically charged water droplets to the first moisture panel 204. The atomized spray of electrostatically charged water droplets and the first moisture panel 204 are oppositely charged.
For example, the first nozzle array 308 can include nozzles, each of which can include a barrel. An electrical charge can be applied to the barrel of each of the nozzles, which applies a charge to the fluid (e.g., water) and/or water droplets. As the fluid is propelled through the nozzle, the water gains an electric charge. For example, the barrel of the nozzle can transfer a negative charge to the droplets (e.g., water droplets, etc.). The first moisture panel 204 can be positively charged (or grounded) to create an attractive force to the droplets. The positively charged first moisture panel 204 can create an attraction to the negatively charged droplets. Alternatively, the barrel of the nozzle can transfer a positive charge to the droplets (e.g., water droplets, etc.) and the first moisture panel 204 can be negatively charged (or grounded). The negatively charged first moisture panel 204 can create an attraction to the positively charged droplets.
Electrostatically spraying droplets onto the first moisture panel 204 can allow more water to land on the charged first moisture panel 204. Electrostatically spraying droplets onto the first moisture panel 204 can allow more water to be retained by the first moisture panel 204. Due to the charge, when the water leaves the nozzle, the water is attracted to the first moisture panel 204 and “sticks” (e.g., wets, adheres, etc.) to the first moisture panel 204. The attraction improves coverage of wetting on the moisture panels and minimizes dry spots. The attraction also improves the water efficiency by more effectively covering the surface that results in less water usage. The attraction further reduces “blow-through” of moisture through the moisture panels. For example, the electrostatic attraction of the atomized spray of electrostatically charged droplets and the moisture panels substantially prevents blow-through of droplets beyond an inside surface of the moisture panel.
The gas cooler unit 302 also includes a second nozzle array 310 (e.g., second water spray nozzle array, one or more spray nozzles, etc.). The second nozzle array 310 can be disposed external to the second moisture panel 206. For example, the second nozzle array 310 can be located on the exterior of the second moisture panel 206. The second nozzle array 310 can be configured to provide an atomized spray of electrostatically charged water droplets to the second moisture panel 206. The atomized spray of electrostatically charged water droplets and the second moisture panel 206 are oppositely charged.
For example, the second nozzle array 310 can include nozzles, each of which can include a barrel. An electrical charge can be applied to the barrel of each of the nozzles, which applies a charge to the fluid (e.g., water) and/or water droplets. As the fluid is propelled through the nozzle, the water gains an electric charge. For example, the barrel of the nozzle can transfer a negative charge to the droplets (e.g., water droplets, etc.). The second moisture panel 206 can be positively charged (or grounded) to create an attractive force to the droplets. The positively charged second moisture panel 206 can create an attraction to the negatively charged droplets. Alternatively, the barrel of the nozzle can transfer a positive charge to the droplets (e.g., water droplets, etc.) and the second moisture panel 206 can be negatively charged (or grounded). The negatively charged second moisture panel 206 can create an attraction to the positively charged droplets.
Electrostatically spraying droplets onto the second moisture panel 206 can allow more water to land on the charged second moisture panel 206. Electrostatically spraying droplets onto the first moisture panel 204 can allow more water to be retained by the second moisture panel 206. Due to the charge, when the water leaves the nozzle, the water is attracted to the second moisture panel 206 and “sticks” (e.g., wets, adheres, etc.) to the second moisture panel 206. In some implementations, the first nozzle array 308 and the second nozzle array 310 form a single nozzle array.
Control system 304 includes controller 314, flow control valve 318, and flow sensor 320. Controller 314 is coupled to the flow control valve 318 and water flow sensor 320. Control system 304 is coupled to a moisture sensor 330. In some implementations, the control system 304 can be couple to a relative humidity sensor, ambient dry bulb temperature sensor, and/or an overflow pan level sensor. Controller 314 can use signals from the moisture sensor 330 and other connected sensors to operate the flow control valve 318 to regulate a flow of liquid to gas cooler unit 302. In some implementations, a system includes a pump. For example, in some installations, fluid supply pressure can be insufficient, and a pump can be used to increase the fluid supply pressure. In some cases, a fan speed signal is sent by an external controller (e.g., a 0-10 VDC signal can be intercepted to use for this purpose).
In some implementations, a system includes multiple flow control valves. The valve(s) can be controlled, for example, by an analog signal (e.g., 4-20 mA, 0-10 VDC) representing percentage open to position it directly or if using a stepper valve, through a stepper driver. Alternatively, fluid flow can be controlled using a pulse width modulation (PWM) approach and simple solenoid valves (a single valve or individual nozzle valves). In this case, the requested percentage open can be equivalent to the percentage of the PWM period.
Controller 314 can receive signals from one or more measurement devices (e.g., pressure sensors, temperature sensors, flow sensors, etc.) located within system 300. For example, controller 314 is shown receiving measurements from a moisture sensor 330. Controller 314 can use the input signals to determine appropriate control actions for controllable devices of a system (e.g., compressors, pumps, valves, etc.). In certain implementations, a moisture sensor (e.g., moisture sensor 330) is used for predictive assessments and accuracy, with or without being used for control.
In some implementations, controller 314 is configured to operate control valve 318 at a desired setpoint or within a desired range. In some implementations, controller 314 operates high-pressure valves and expansion valves of MT subsystem, LT subsystem, and primary subsystem to regulate the flow of refrigerant and various sub-systems of a system (e.g., system 100 shown in
Controller 314 can include feedback control functionality for adaptively operating the various components of cooling system 300. For example, controller 314 can receive a setpoint (e.g., a level setpoint, a temperature setpoint, a pressure setpoint, a flow rate setpoint, a power usage setpoint, etc.) and operate one or more components of system 300 to achieve the setpoint. The setpoint can be specified by a user (e.g., via a user input device, a graphical user interface, a local interface, a remote interface, etc.) or automatically determined by controller 314 based on a history of data measurements.
Controller 314 can be a proportional-integral (PI) controller, a proportional-integral-derivative (PID) controller, a pattern recognition adaptive controller (PRAC), a model recognition adaptive controller (MRAC), a model predictive controller (MPC), or any other type of controller employing any type of control functionality. In some implementations, controller 314 is a local controller for cooling system 300. In other implementations, controller 314 is a supervisory controller for a plurality of controlled subsystems (e.g., a refrigeration system, an AC system, a lighting system, a security system, etc.). For example, controller 314 can be a controller for a comprehensive building management system incorporating system 300. Controller 314 can be implemented locally, remotely, or as part of a cloud-hosted suite of building management applications.
Controller 314 can be configured to control a supply of fluid to at least one of the first moisture panel 204 or the second moisture panel 206 (e.g., individually or in combination) in response to flow rate signals. For example, the controller 314 can be configured to control a supply of liquid to the first moisture panel 204 and the second moisture panel 206 in response to the signal representative of a setpoint liquid flow rate. For example, the controller 314 can decrease the supply of liquid to the one or more moisture pads in response to a signal that the flow rate is higher than a setpoint level. The controller 314 can increase the supply of liquid to the one or more moisture pads in response to a signal that the flow rate is lower than the setpoint level. The controller 314 can retain (e.g., maintain, hold constant) the supply of water to the moisture pads in response to a signal that the flow rate is at the setpoint.
The controller 314 can be configured to control the supply of liquid using a variable rate controller (e.g., flow control valve, etc.). For example, the variable rate controller can adjust the application rate of droplets to an optimal amount for each moisture panel or for a single moisture panel. For example, the variable rate controller can provide a higher application rate of droplets to the first moisture panel 204 than to the second moisture panel 206, or vice versa.
In some implementations, the controller 314 can be configured to supply a voltage to the nozzles of the first nozzle array 308 and the second nozzle array 310. The controller 314 can select the voltage so as to cause the first nozzle array 308 and the second nozzle array 310 to provide a target amount of electrostatically charged droplets. The controller 314 can select the voltage so as to cause the one or more spray nozzles to provide a target amount of electrostatically charged droplets. For example, the target amount of electrostatically charged droplets can include an amount of electrostatically charged droplets that does not cause excess water to leave the first moisture panel 204 and the second moisture panel 206.
In some implementations, the controller 314 can be incorporated into a system level control device (such as a condensing unit rack controller) that is configured to operate the any or all other components of the system such as the evaporator, the compressor, the gas cooler, the receiver, and the expansion valve. For example, the controller 314 can be configured to operate the MT evaporators 12. The controller 314 can be configured to operate the LT evaporators 22. The controller 314 can be configured to operate the MT compressors 14. The controller 314 can be configured to operate the LT compressors 24. The controller 314 can be configured to operate the gas cooler/condenser 2. The controller 314 can be configured to operate the gas cooler 200. The controller 314 can be configured to operate the receiving tank 6. The controller 314 can be configured to operate the expansion valves 11.
In some implementations, the fluid flow meter 320 can be positioned downstream of the injector 342 such that the flow meter 320 measures the mixed flow from the collected portion of liquid and the liquid supply. The controller 314 can be configured to adjust the flow control valve 318 to account for the recirculated liquid introduced by injector 342. For example, the controller 314 can be configured to operate the flow control valve 318 to adjust the flow of the liquid supply based at least in part on the measured flow rate. The controller 314 can be configured to operate the flow control valve 318 to adjust the flow of supply liquid to be less than the measured flow rate to account for the liquid drawn into the injector from the basin.
The basin 410 is configured to collect a portion of liquid 424 from evaporative pads or moisture panels of a cooling system (e.g., 206 and 208). The liquid 424 in the basin 410 can be unevaporated liquid, run off, or “blow through.” The second fluid entering the injector can be the liquid 424 or air. For example, in some implementations, when there is liquid 424 in the basin 410, the second fluid can be the liquid 424, and when there is no liquid 424 in the basin 410, or when the level of the liquid is below a threshold level, the second fluid can be air. In implementations where one of the first fluid or the second fluid is a gas and the other is a liquid, a gas-liquid mixture is discharged through the outlet of the injector.
The flow rate of the second fluid 454 through the second inlet 408 is much less than the flow of the first fluid 406 through the first inlet 404. For example, the flow of the second fluid 454 through the second inlet 408 can be an order of magnitude lower than the flow rate of the first fluid 406 through the first inlet 404. In one example, the pressure at the first inlet is 30 psig, and the pressure at the outlet is 20 psig. The flow rate through the first inlet is 23.4 gph while the flow rate through the second inlet is 0.86 gph. In another example, the pressure at the first inlet is 50 psig, the pressure at the outlet is 30 psig, the flow rate at the first inlet is 42 gph, and the flow rate at the second inlet is 4.45 gph.
An injector 400 with a venturi 450 internal geometry operates as a passive device. The injector 400 does not use electricity or a pump to suction the second fluid 454 into the second inlet 408. The injector 400 also does not need to be primed to start suctioning fluid. As a result, in the absence of a liquid 424 in the basin 410, the injector 400 can be configured to draw air into the injector 400 through the second inlet 408. If the basin 410 subsequently collects additional liquid 424, the injector 400 can automatically without intervention suction the liquid 424 into the injector 400. One advantage of the ability to run dry is that a liquid level does not need to be maintained within the basin 410 allowing for a reduction of potential waste. Another advantage is the injector 400 operates with less liquid to be recirculated than a pump can require. In some cases, the injector 400 can operate with ten to twenty times less liquid than a submersible recirculating pump. The lack of moving parts within the injector 400 also promotes longevity of the injector 400 reducing maintenance and repair or replacement costs.
The injector 504 is positioned downstream of the flow control valve 502 in this example implementation. The supply of fluid 512 is provided through the flow control valve 502 to a first inlet 514 of the injector 504. The second inlet 516 of the injector is coupled to the basin 510. The basin 510 is configured to collect a portion of liquid 511 from evaporative pads or moisture panels of the cooling system. In some aspects, a check valve 518 is coupled between the basin 510 and the second inlet 516. The check valve 518 can be configured to allow flow in one direction (e.g., from the basin 510 to the injector 504) thereby preventing fluid from the supply of fluid 512 from flowing out of the second inlet 516. In some implementations, a filter 520 is coupled between the basin 510 and the second inlet 516. The filter 520 can block contaminates from being recirculated into the assembly 500. In some instances, the filter 520 is a calcium filter.
The fluid from the first inlet 514 and the fluid from the second inlet 516 mix in the injector 504. The mixture is discharged through the outlet 522. The flow meter 506 is coupled to the outlet 522 of the injector 504. The flow meter 506 is configured to measure the flow rate of the mixture of fluid discharged from the outlet 522. In some implementations, the flow rate of the fluid through the second inlet 516 can be determined based on the configured settings of the flow control valve 502 and the measured flow rate from the flow meter 506. A controller (e.g., controller 314) can be configured to adjust the flow control valve 502 based in part on the determined flow rate through the second inlet 516.
The flow meter 506 is coupled downstream to a nozzle assembly 508. In some implementations, more than one nozzle assembly can be coupled downstream of the flow meter 506. The nozzle assembly 508 includes a header 532, and one or more nozzles 534. In some implementations, the nozzles 534 are electrostatic nozzles. In some implementations, the nozzles 534 are drip nozzles.
In an example operation of assembly 500, a flow of a first fluid 512 is provided to the first inlet 514 of the injector 504. In some implementations, the first fluid 512 is water. In some implementations, the first fluid 512 is air. A second fluid is drawn from the basin 510 into the second inlet 516 of the injector 504. In some aspects, the second fluid is the collected portion of liquid 511 (e.g., water), and in some aspects, the second fluid can be air. A mixture of the first fluid and the second fluid is discharged through the outlet 522 of the injector 504 to one or more nozzle assemblies (e.g., 508).
In some implementations, the operations further include controlling a flow of the first fluid 512 into the first inlet 514 of the injector 504 using a flow control valve 502 communicatively coupled to a controller (e.g., 314). In some implementations, the one or more nozzle assemblies 508 can include drip nozzles. In these implementations, the operations further include distributing liquid to the one or more evaporative pads through the drip nozzles of the one or more nozzle assemblies. In some implementations, the one or more nozzle assemblies 508 include electrostatic spray nozzles, and the operations include distributing a liquid with an electrostatic charge to the one or more evaporative pads.
The liquid stream 610 and the air stream 615 can meet at a tip of the nozzle. For example, the low pressure and high volume air flow can atomize the liquid into droplets 620. The droplets 620 can be uniform in size. The droplets 620 can pass through an electric field. For example, an electrode 625 of the nozzle 605 can apply a charge (e.g., positive charge, negative charge, etc.) to the droplets 620. The droplets 620 can be carried towards a spray target 630 (e.g., first moisture panel 204, second moisture panel 206, etc.). The spray target 630 can have an opposite charge than that of the droplets 620. For example, the spray target 630 can have a positive charge and the droplets 620 can have a negative charge. Alternatively, the spray target 630 can have a negative charge and the droplets 620 can have a positive charge. The charged droplets 620 are attracted to the oppositely charged spray target 630.
The controller 700 includes a processor 710, a memory 720, a storage device 730, and an input/output device 740. Each of the components 710, 720, 730, and 740 are interconnected using a system bus 750. The processor 710 is capable of processing instructions for execution within the controller 700. The processor can be designed using any of a number of architectures. For example, the processor 710 can be a CISC (Complex Instruction Set Computers) processor, a RISC (Reduced Instruction Set Computer) processor, or a MISC (Minimal Instruction Set Computer) processor.
In one implementation, the processor 710 is a single-threaded processor. In another implementation, the processor 710 is a multi-threaded processor. The processor 710 is capable of processing instructions stored in the memory 720 or on the storage device 730 to display graphical information for a user interface on the input/output device 740.
The memory 720 stores information within the control system 700. In one implementation, the memory 720 is a computer-readable medium. In one implementation, the memory 720 is a volatile memory unit. In another implementation, the memory 720 is a non-volatile memory unit.
The storage device 730 is capable of providing mass storage for the controller 700. In one implementation, the storage device 730 is a computer-readable medium. In various different implementations, the storage device 730 can be a floppy disk device, a hard disk device, an optical disk device, a tape device, flash memory, a solid state device (SSD), or a combination thereof.
The input/output device 740 provides input/output operations for the controller 700. In one implementation, the input/output device 740 includes a keyboard and/or pointing device. In another implementation, the input/output device 740 includes a display unit for displaying graphical user interfaces.
The features described can be implemented in digital electronic circuitry, or in computer hardware, firmware, software, or in combinations of them. The apparatus can be implemented in a computer program product tangibly embodied in an information carrier, for example, in a machine-readable storage device for execution by a programmable processor; and method steps can be performed by a programmable processor executing a program of instructions to perform functions of the described implementations by operating on input data and generating output. The described features can be implemented advantageously in one or more computer programs that are executable on a programmable system including at least one programmable processor coupled to receive data and instructions from, and to transmit data and instructions to, a data storage system, at least one input device, and at least one output device. A computer program is a set of instructions that can be used, directly or indirectly, in a computer to perform a certain activity or bring about a certain result. A computer program can be written in any form of programming language, including compiled or interpreted languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment.
Suitable processors for the execution of a program of instructions include, by way of example, both general and special purpose microprocessors, and the sole processor or one of multiple processors of any kind of computer. Generally, a processor will receive instructions and data from a read-only memory or a random access memory or both. The essential elements of a computer are a processor for executing instructions and one or more memories for storing instructions and data. Generally, a computer will also include, or be operatively coupled to communicate with, one or more mass storage devices for storing data files; such devices include magnetic disks, such as internal hard disks and removable disks; magneto-optical disks; and optical disks. Storage devices suitable for tangibly embodying computer program instructions and data include all forms of non-volatile memory, including by way of example semiconductor memory devices, such as EPROM, EEPROM, solid state drives (SSDs), and flash memory devices; magnetic disks such as internal hard disks and removable disks; magneto-optical disks; and CD-ROM and DVD-ROM disks. The processor and the memory can be supplemented by, or incorporated in, ASICs (application-specific integrated circuits).
To provide for interaction with a user, the features can be implemented on a computer having a display device such as a CRT (cathode ray tube) or LCD (liquid crystal display) or LED (light-emitting diode) monitor for displaying information to the user and a keyboard and a pointing device such as a mouse or a trackball by which the user can provide input to the computer. Additionally, such activities can be implemented via touchscreen flat-panel displays and other appropriate mechanisms.
The features can be implemented in a control system that includes a back-end component, such as a data server, or that includes a middleware component, such as an application server or an Internet server, or that includes a front-end component, such as a client computer having a graphical user interface or an Internet browser, or any combination of them. The components of the system can be connected by any form or medium of digital data communication such as a communication network. Examples of communication networks include a local area network (“LAN”), a wide area network (“WAN”), peer-to-peer networks (having ad-hoc or static members), grid computing infrastructures, and the Internet.
While this specification contains many specific implementation details, these should not be construed as limitations on the scope of any inventions or of what can be claimed, but rather as descriptions of features specific to particular implementations of particular inventions. Certain features that are described in this specification in the context of separate implementations can also be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation can also be implemented in multiple implementations separately or in any suitable subcombination. Moreover, although features can be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination can be directed to a subcombination or variation of a subcombination.
Similarly, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing can be advantageous. Moreover, the separation of various system components in the implementations described above should not be understood as requiring such separation in all implementations, and it should be understood that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products.
A number of implementations have been described. Nevertheless, it will be understood that various modifications can be made without departing from the spirit and scope of the disclosure. For example, example operations, methods, or processes described herein can include more steps or fewer steps than those described. Further, the steps in such example operations, methods, or processes can be performed in different successions than that described or illustrated in the figures. Accordingly, other implementations are within the scope of the following claims.
