Humidity control and air conditioning

Abstract

Air conditioning systems that cool and dehumidify spaces within enclosures, buildings having such systems, and methods of controlling humidity within a space. Embodiments adjust speed of a blower or fan motor based on inputs from sensors within the system, using automated processes, to reduce airflow rates to provide for lower temperatures of the cooling coil and to increase the ratio of latent to sensible heat transfer. Fan speeds may be increased as appropriate to avoid frost formation on the cooling coil, to give priority to cooling when temperatures within the space are high, or periodically to provide for mixing within the space.

Description

FIELD OF INVENTION

This invention relates to systems and methods for controlling humidity, heating, ventilating, and air-conditioning (HVAC) equipment, systems and methods, and control equipment. Specific embodiments relate to mass-produced air conditioning units, for example, for residential applications, and to their controls.

BACKGROUND OF THE INVENTION

Heating, ventilating, and air-conditioning (HVAC) systems have been used to ventilate and maintain desirable temperatures within spaces such as buildings, for occupants to live and work, for example. Air conditioning units have been known to remove humidity from the air, as well as reducing the temperature of the air, and humidity reduction has contributed to making spaces within enclosures more comfortable, particularly in hot and humid climates or conditions. However, it has also been known that humidity can cause frost formation on evaporator coils, and such frost formation has, on more than one occasion, blocked airflow through the evaporator coil, reduced the effectiveness of heat transfer to an evaporator coil, or both. Further, it has been known that frost formation on evaporator coils can, in many cases, be avoided by maintaining adequate air flow through the evaporator coils so that the temperature of the evaporator coil remains above or substantially above a freezing temperature. Accordingly, in many air conditioning units, blowers have been sized to provide adequate flow to prevent frost formation on evaporator coils.

In addition, certain HVAC units have been used that have had variable speed fans or blowers. Some such systems have been used in variable air volume (VAV) systems, for example, and have used variable speed drive units, such as variable frequency AC drive units or variable voltage DC systems. However, even variable-speed blowers have typically been operated at high-enough speeds to maintain evaporator temperatures well above freezing.

Air conditioning units typically use a significant amount of energy in their operation, and steps have been taken to improve the energy efficiency or coefficient of performance of air conditioning units, including units for residential applications, for instance. One change that has been made to air conditioning units to improve the coefficient of performance has been to increase the surface area of the indoor coil or evaporator coil, and the supply airflow rate relative to the total amount of heat transfer. This results in a higher evaporator or cooling coil temperature generally. Although coefficient of performance is typically improved by these changes, due to the higher airflow rates relative to the total amount of heat transfer, air temperatures (e.g., of supply air) are not reduced as much, and humidity levels in the space typically are not reduced as much as a result. Such increases in humidity levels may be acceptable if humidity levels are not very high to start with; however, needs or potential for benefit exist for HVAC equipment, systems, and methods that provide for greater humidity reduction, for example, when humidity levels are excessive.

Needs or potential for benefit exist for equipment, systems, and methods that at least partially compensate for changes in humidity levels, for example, selecting priorities between emphasizing or maximizing coefficient of performance and emphasizing or maximizing humidity reduction. In addition, in at least some applications, needs or potential for benefit exist for systems or methods that emphasize capacity (e.g., total heat transfer) when temperatures are excessive, but that may emphasize humidity reduction (e.g., if humidity levels are excessive) when temperatures are closer to desired values. Further, needs or potential for benefit exist for such equipment, systems, and methods that are inexpensive, utilize existing components (e.g., to a greater degree than alternatives), are reliable, are easy to place into service by typical installation personnel, or a combination thereof. Needs or potential for benefit exist for such equipment, systems, and methods in typical residential applications, for example, such as mass-produced residential air-conditioning units, heat pumps, furnaces, and the like, that are suitable to be installed by typical installers of such equipment. Potential for improvement exists in these and other areas that may be apparent to a person of skill in the art having studied this document.

SUMMARY OF PARTICULAR EMBODIMENTS OF THE INVENTION

This invention provides, among other things, air conditioning units and systems that cool and dehumidify spaces within enclosures, and methods of controlling humidity within a space, for example, using an air conditioning unit or system. Different embodiments adjust or vary speed or torque of a blower or fan motor based on inputs from sensors within the system, using automated processes, or both, for example. Various embodiments of the invention provide as an object or benefit that they partially or fully address one or more of the needs, potential areas for improvement or benefit, or functions described herein, for instance. Specific embodiments provide as an object or benefit, for instance, that they at-least partially provide for control of humidity within a space, provide for control of HVAC equipment or systems, or provide specific air conditioning systems, equipment, or units, or a combination thereof, for example. In many embodiments, a controller is used to control various equipment, and such a controller may be a digital controller, for example. In some embodiments, an object or benefit is to control humidity while avoiding frost formation on a cooling coil, as another example. Various embodiments reduce airflow rates under appropriate conditions to provide for lower temperatures of the cooling coil and supply air to reduce humidity. Fan speeds may be increased under appropriate conditions to avoid frost formation on the cooling coil, to give priority to cooling when temperatures within the space are high, or periodically to provide for mixing within the space, as examples.

Various embodiments provide equipment, systems, and methods that are reasonably inexpensive, utilize existing components to at least some degree, are reasonably reliable, and can reasonably be placed into service by typical installation personnel, for example, typical service personnel in residential installations. Further still, particular embodiments provide equipment, systems, and methods that control or maintain (at least to some extent) humidity within desired ranges or toward desired goals. Different embodiments may provide for reduced energy consumption in comparison with certain alternatives, may provide for reduced noise, may avoid insufficient or excessive airflow rates, may provide for sufficient airflow through evaporator coils to prevent frost formation, or a combination thereof, as further examples.

In specific embodiments, this invention provides air conditioning systems for cooling and dehumidifying a space within an enclosure. Such air conditioning systems include a cooling coil positioned within the system and configured to cool air to be delivered from the air conditioning system to the space, a first fan positioned and configured to move the air through the cooling coil and to the space, a first electrical motor connected to and configured to turn the first fan, and a first variable-speed drive system configured and at least electrically connected to drive the first electrical motor. These air conditioning systems also include a first sensor positioned and configured to sense a first condition within the space or the air, and the first condition comprises a humidity. Such air conditioning systems also include a second sensor positioned and configured to sense a second condition at the cooling coil, and a controller that is in communication with the first variable-speed drive system and in communication with the first sensor and the second sensor. In these embodiments, the controller is configured to cause the first variable-speed drive system to change the speed of the first electrical motor in response to the first condition sensed by the first sensor and in response to the second condition sensed by the second sensor.

In some such embodiments, the second condition is the temperature at the cooling coil, for example. In addition, in a number of these embodiments, the controller is configured to cause the first variable-speed drive system to reduce the speed of the first electrical motor in response to an excessive humidity condition sensed by the first sensor. Furthermore, in certain embodiments, the controller is configured to cause the first variable-speed drive system to stop reducing the speed of the first electrical motor to avoid frost formation on the cooling coil, and in some embodiments, the controller is configured to cause the first variable-speed drive system to actually increase the speed of the first electrical motor to avoid frost formation on the cooling coil.

In various of these embodiments, the cooling coil is an evaporator coil, and the air conditioning system further comprises, within a single enclosure for the air conditioning system, an expansion valve, a compressor, an electric second motor connected to and configured to turn the compressor, a condenser coil, a second fan configured to blow air through the condenser coil, and an electric third motor connected to and configured to turn the second fan. Still further, some embodiments further include a third sensor positioned and configured to sense a third condition within the space or the air, and this third condition may be a temperature within the space or the air, for example. In some such embodiments, the controller is in communication with the third sensor and is further configured to forgo causing the first variable-speed drive system to reduce the speed of the first electrical motor in response to the first condition sensed by the first sensor if the third condition exceeds a threshold. In certain embodiments, the third sensor includes, or is part of, a system controller located within the space, and in some embodiments the threshold is relative to a temperature set point of the system controller.

Other embodiments of the invention are (or include) a building that includes at least one embodiment of the air conditioning system described above, and the building forms the enclosure in many such embodiments. Still other specific embodiments include various methods of controlling humidity within a space. Certain such methods include (e.g., at least) the act or activity of providing or obtaining an air-conditioning unit that includes a cooling coil and a variable-speed fan, wherein the fan is positioned and configured to move air through the cooling coil to the space. These methods also include the acts or activities of measuring humidity using an automated process to obtain a humidity measurement, and using an automated process, using the humidity measurement to determine whether to reduce the humidity. Such methods also include the acts or activities of using an automated process, and dependent upon the humidity measurement, lowering the speed of the fan to decrease the cooling coil temperature, thus increasing the latent component of energy absorption at the cooling coil, resulting in a reduction of the humidity relative to a humidity level that would have resulted from not lowering the speed of the fan. These examples of methods also include the acts of using an automated process, measuring a second condition at the cooling coil, and using an automated process, controlling the speed of the fan using the second condition to avoid frost formation on the cooling coil.

A number of these methods further include the act of, using an automated process, measuring a first temperature within the space, and the act of reducing of the speed of the fan is performed only if the first temperature is below a first threshold temperature. In addition, in some embodiments, the second condition is a temperature of the cooling coil and the speed of the fan is controlled using the second temperature to avoid having the second temperature drop below freezing. Further, certain of these methods further include the act of repeating at least a plurality of times the lowering of the speed of the fan, which is performed in discrete increments wherein the speed of the fan is held substantially constant for a period of time for each of the distinct increments. The act of measuring the temperature of the cooling coil during each period of time may also be repeated, and the lowering of the speed of the fan may be performed in a subsequent discrete increment only if the temperature of the cooling coil is above a first temperature threshold. Even further, some embodiments further include an act of raising of the speed of the fan, which may be performed in discrete increments, and the speed of the fan may be held substantially constant for a period of time for each of the distinct increments. The temperature of the cooling coil may be measured during each period of time, and the raising of the speed of the fan may be performed in a subsequent discrete increment only if the temperature of the cooling coil is below a second temperature threshold.

Still other embodiments of the invention include, as another example, particular methods of controlling humidity within a space using an air-conditioning unit. Such an air conditioning unit may include a cooling coil and a variable-speed fan, and the fan may blows air through the cooling coil. Such methods include (e.g., in any order) acts or activities of receiving a temperature set point for the space, measuring an actual temperature within the space, evaluating whether the actual temperature within the space is within a predetermined offset of the temperature set point, and measuring an actual humidity in the space or air drawn from the space. Such methods also include acts of evaluating whether the actual humidity exceeds a predetermined humidity threshold, and if, and only if, the actual temperature within the space is within the predetermined offset of the temperature set point, and the actual humidity exceeds the predetermined humidity threshold, lowering the speed of the fan to reduce the humidity.

Some of these methods further include acts of monitoring at least a first condition of the cooling coil and increasing the speed of the fan to avoid freezing of the cooling coil, and in particular embodiments the act of monitoring of the first condition of the cooling coil comprises monitoring of a temperature at the cooling coil. In addition, in a number of embodiments, the act of lowering the speed of the fan includes (e.g., in the following order), the acts of lowering the speed by a discrete speed increment, operating the fan at a substantially constant speed for a discrete increment of time, measuring the first condition, and repeating the lowering of the speed by a discrete speed increment, operating of the fan at a substantially constant speed for a discrete increment of time, and measuring of the first condition, until the first condition reaches a first threshold value.

In some embodiments, the act of increasing the speed of the fan comprises the acts of increasing the speed by a discrete speed increment, operating the fan at a substantially constant speed for a discrete increment of time, measuring the first condition, and repeating the increasing of the speed by a discrete speed increment, operating the fan at a substantially constant speed for a discrete increment of time, and measuring the first condition, until the first condition reaches a second threshold value. Further, in various embodiments. the first condition includes (or is) a temperature at the first coil, the first threshold value is a first temperature above freezing and the second threshold value is a second temperature above the first temperature. Still further, some such methods further include the acts of increasing the speed of the fan after a first time period to insure proper air distribution within the space, and then returning after a second time period to the lowering of the speed of the fan to reduce the humidity.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating, among other things, an air conditioning unit and system, installed on a building, that illustrates various examples of embodiments of the invention; and

FIG. 2 is a flow chart illustrating examples of various methods, including, as examples, methods of controlling humidity within a space.

The drawings illustrate, among other things, various particular examples of embodiments of the invention, and certain examples of characteristics thereof. Different embodiments of the invention include various combinations of elements or activities shown in the drawings, described herein, known in the art, or a combination thereof.

DETAILED DESCRIPTION OF EXAMPLES OF EMBODIMENTS

In a number of embodiments, this invention provides improvements to heating, ventilating, and air-conditioning (HVAC) systems, buildings having such systems, methods, and controls. Various embodiments adjust or vary speed or torque of a blower or fan motor based on inputs from sensors within the system, using automated processes, or both, for example. Various embodiments at-least partially provide for control of humidity within a space, provide for control of HVAC equipment or systems, or provide specific air conditioning systems, equipment, or units, or a combination thereof, for example. In many embodiments, a controller is used to control certain equipment, and such a controller may be a digital controller, for example. Some embodiments control humidity while avoiding frost formation on a cooling coil.

In some embodiments, air conditioning units may be mass produced in common configurations and installed in different buildings or structures. In such applications, airflow rates may be controlled to at least partially control humidity levels. In particular embodiments, for example, the speed, torque, or both, of a fan motor may be varied to obtain a desired humidity level, a humidity level that is within a particular range, or a more desirable humidity level. Such a process may be automated, continuous, or both, in various embodiments. Various embodiments adjust speed of a blower or fan motor based on inputs from sensors within the system, using automated processes, to reduce airflow rates to provide for lower temperatures of the cooling coil and supply air to reduce humidity. Fan speeds may be increased to avoid frost formation on the cooling coil, to give priority to cooling when temperatures within the space are high, or periodically to provide for mixing within the space, as examples.

FIG. 1 illustrates an example of both embodiments of the invention and an environment in which embodiments of the invention may be used. In this embodiment, air-handling unit or air conditioning unit 10 is used for ventilating an at-least partially enclosed space 11. In addition, in this embodiment, space 11 is enclosed by or within building or structure 19, which may be a residence such as a single family house, an apartment, a portion of a duplex, triplex, or fourplex, or a cabin, or may be a hotel room, a business establishment such as a store or a restaurant, or the like. Building 19 is an example of particular embodiments of the invention that are (or include) a building (e.g., 19) that includes at least one embodiment of the air conditioning unit (e.g., 10) or system (e.g., 10s) described herein. The building 19 forms the enclosure 11 in the embodiment illustrated. In many embodiments, residential use is the predominant market for air handling unit 10, for instance.

In this embodiment, air conditioning unit 10 includes a first fan 12a that is configured to move or blow air through air conditioning unit 10 and to space 11. In this embodiment, supply air 16s is delivered to space 11 through ductwork 16a and registers 16w, 16x, and 16y. Further, in this embodiment, return air 16r is fed to air conditioning unit 10 through return air ductwork 16b, filter 16f, and grille 16z, as may be found in a residential application, for example. In other embodiments, fan 12a may be fed with outside air, or a combination of outside and return air, for example. As would be apparent to a person of ordinary skill in the art, air handling unit 10 and structure 19 are not shown to scale relative to each other in FIG. 1, and other components illustrated may also not be shown to scale. Fan 12a, in different embodiments, may be an axial or propeller-type fan (as shown), a centrifugal fan [e.g., with forward curved (e.g., a squirrel cage fan) or backward curved vanes (e.g., airfoil shaped)], or a mixed flow fan, as examples.

In the embodiment illustrated, air-handling or air conditioning unit 10, ductwork 16a and 16b, registers 16w, 16x, and 16y, filter 16f, grille 16z, and thermostat 16t, form ventilation system 10s. In this embodiment, within air conditioning unit 10, electric first motor 13a is connected to and configured to turn first fan 12a. As used herein, “connected to and configured to turn” includes through a common rotating shaft (as illustrated), directly coupled, through a belt drive (e.g., which may have an adjustable sheave or pulley), or integral (e.g., an integral fan and motor), for example. In this example of an embodiment, motor 13a is driven or powered by drive unit 15 through leads 15a and 15b. Drive unit 15 may be an electronic control module, for example. In some embodiments, motor 13a is an alternating current (AC) motor, and drive unit 15 is a variable frequency drive unit, for example. In such embodiments, motor 13a may be a two-phase motor and may have two leads 15a and 15b (as shown) or may have three or more phases and a corresponding number of leads, in other embodiments, as other examples. In AC embodiments, drive unit 15 may be configured to produce a varying frequency AC power supply to motor 13a through leads 15a and 15b to control the speed of motor 13a and fan 12a, for instance.

In other embodiments, motor 13a may be a direct current (DC) motor and drive unit 15 may be a DC power supply, which may be configured to produce a varying DC output voltage to motor 13a through leads 15a and 15b to control the torque to, and therefore the speed of, motor 13a and fan 12a, for example. In still other embodiments, drive unit 15 may be a variable frequency AC power supply, but may provide for control of torque. In still other embodiments, drive unit 15 may be a DC power supply, but may provide for control of speed. Although shown in FIG. 1 as a separate components, in some embodiments, drive unit 15 may be integral with motor 13a.

Still referring to FIG. 1, drive unit 15, and thereby motor 13a and fan 12a, may be controlled by control system or controller 14. In this embodiment, drive unit 15 and controller 14 are shown as separate devices; however, in other embodiments, drive unit 15 and controller 14 may be integral, controller 14 may be part of drive unit 15, or drive unit 15 may be part of controller 14, as examples. Controller 14 may include, or consist of, in some embodiments, an electronic board dedicated for this purpose or combined with one or more other electronic boards such as a furnace, air handler, or thermostat board, as examples. In this embodiment, controller 14 is shown to be within enclosure 18 of air conditioning unit 10, but in other embodiments, controller 14 may be located elsewhere, for example, within structure 19, or within space 11. And in some embodiments, controller 14 may be combined with or integral to a thermostat (e.g., thermostat 14t) or user-accessible control panel, for example. Further, in some embodiments, controller 14 may be digital, and may include a digital processor, software, storage, memory, etc. Still further, in some embodiments, a user interface may be provided which may include a keypad, a display, or the like. Such a user interface may be part of controller 14, part of thermostat 14t, or may be a separate component, in various embodiments.

In a number of embodiments, controller 14 may output instructions to drive unit 15. In some embodiments, controller 14 outputs instructions to other components of air conditioning unit 10 as well, or may have other outputs, in addition to those described herein. Output instructions from controller 14 to drive unit 15 may be transmitted through data link 14a, for instance, and may include, for example, input settings, which may include instructions for drive unit 15 to operate motor 13a at a particular speed or torque, for example. In some embodiments, controller 14 may instruct drive unit 15 to operate motor 13a at a particular AC frequency or at a particular DC voltage, as other examples. Data link 14a (or other data links) may include one or more conductors, which may communicate digital or analogue signals, for example. These conductors may be insulated, shielded or both. In other embodiments, data link 14a may include a wireless connection, communication over power conductors, communication through a network, fiber-optic communication, or the like.

In a number of embodiments, controller 14 may also input data, measurements, or instructions from sensors or other devices and may use such inputs to calculate, select, or determine output instructions, such as input settings for drive unit 15, for example, or speeds or torques for one or more motors (e.g., motor 13a). Examples of such sensors include temperature sensors, humidity sensors, pressure sensors (which may measure absolute pressure, gauge pressure, differential pressure, or a combination thereof), optical sensors, proximity probes, force sensors, flow meters, conductivity or resistance sensor, etc. Sensors may convert parameters into an electrical signal, for example, an analogue (e.g., a voltage, current, resistance, capacitance, etc.) or digital signal, and such an electrical signal may be delivered, (e.g., through one or more conductors or data links) to controller 14.

In some embodiments, including the embodiment illustrated in FIG. 1, air-handling unit 10 is an air conditioning unit having evaporator 15e. Air handling unit 10 may be a vapor compression cycle unit, for example. Evaporator 15e is an example of a heat-transfer coil configured and positioned so that the air (e.g., return air 16r) blown by first fan 12a through air-handling or air conditioning unit 10 passes through the heat-transfer coil (e.g., 15e) (e.g., becoming supply air 16s). In this example, wherein the heat-transfer coil is an evaporator (15e), a fluid (e.g., a refrigerant, such as Freon) passes through the first heat-transfer coil, and heat is transferred via the heat-transfer coil between the air and the fluid. Thus, in a number of embodiments, air-handling unit 10 is an air conditioning unit, the fluid (e.g., that passes through the heat-transfer coil) is a refrigerant, and the first heat-transfer coil is an evaporator coil or cooling coil (e.g., 15e). In some embodiments, coil 15e is a cooling coil when air conditioning unit 10 is operating in a cooling mode, but is a heating coil when air conditioning unit 10 is operating in a heating mode (e.g., as a heat pump).

In some other configurations, chilled water (e.g., cooled by a chiller) or (e.g., in a heating mode) heated water (e.g., heated with electric heat, by burning a fuel such as natural gas, propane, heating oil, wood, biomass, hydrogen, or coal, produced by solar energy, from a geothermal source, produced as waste heat from an industrial process, produced as heat from cogeneration, or produced as waste heat from chillers or air conditioning units), or steam (e.g., produced similarly or in a boiler) are other examples of fluids that may pass through the heat-transfer coil (e.g., 15e,) or another coil. Such a coil containing chilled water is another example of a cooling coil.

In the particular embodiment illustrated, air conditioning unit 10 further includes, within enclosure 18 for air conditioning unit 10, expansion valve 17b, compressor 17a, an electric second motor 13c connected to and configured to turn compressor 17a, condenser coil 15c, second fan 12b configured to blow air (e.g., outside air 160, which becomes exhaust air 16e) through condenser coil 15c, and electric third motor 13b connected to and configured to turn second fan 12b. Air conditioning unit 10 is an example of a packaged air conditioning unit. In other embodiments, many similar components may be located in a separate enclosure. For example, in some embodiments, (e.g., split systems) components analogous to expansion valve 17b, compressor 17a, electric second motor 13c connected to and configured to turn compressor 17a, condenser coil 15c, second fan 12b configured to blow air (e.g., outside air 160, which becomes exhaust air 16e) through condenser coil 15c, and electric third motor 13b connected to and configured to turn second fan 12b may be located in one or more enclosures outside of structure 19. In such embodiments, components analogous to evaporator 15e, blower or fan 12a, and motor 13a, (or a number of sets of such components) may be located inside structure 19, for example.

In many embodiments, motor 13c may be a constant-speed motor, and compressor 17a may be operated at a constant speed. In other words, air conditioning unit 10 may be a constant capacity unit. In other embodiments, compressor 17a may have multiple speeds (e.g., 2, 3, 4, or 5 speeds). In some embodiments, motor 13c may be a variable-speed motor, and compressor 17a may be operated at variable speeds. In some such embodiments, compressor 17a may be operated at continuously varying speeds over a range of speeds, while in other embodiments, compressor 17a may just be operated at particular speeds within a range (e.g., to avoid resonance frequencies). Further, in some situations, controller 14 may be used to control multiple motor blower assemblies (e.g., motor 13a and fan 12a being one example). In some applications, dip switches, jumpers, or both, may be mounted on the board, for example, to select the desired assembly. In certain embodiments, communication between the control circuit (e.g., of controller 14) and the motor (e.g., 13a being an example) may be used to detect the assemblies.

Certain examples of embodiments of the invention include or provide mass-produced air conditioning units (e.g., air conditioning unit embodiments of air-handling unit 10) for a variety of residential structures (e.g., an example of which is structure 19). Such air conditioning units may include, among other things, evaporator 15e, fan 12a configured to blow air through the air conditioning unit (e.g., through unit 10, evaporator 15e, or both) to space 11, electric motor 13a connected to and configured to turn fan 12a, and control system 14 configured to use one or more inputs to control and vary the speed or the torque of motor 13a. In these embodiments, control system 14 may be configured to repeatedly or continuously (or both) sample one or more inputs (e.g., from one or more sensors) and vary the speed or the torque (or both, e.g., power) of motor 13a to control the airflow rate (e.g., of supply air 16s, return air 16r, or both) through evaporator 15e or through air conditioning unit 10. Different inputs may be used in different embodiments, and various examples are described herein.

In specific embodiments, air conditioning unit 10 or system 10s may be used (possibly among other uses) for cooling and dehumidifying space 11 within enclosure 19, for example. Such an air conditioning unit 10 or system 10s includes, in this embodiment, evaporator or cooling coil 15e positioned within system 10s (e.g., within unit 10 or enclosure 18) and configured to cool air (e.g., cool return air 16r, which becomes supply air 16s) to be delivered from air conditioning system 10s to space 11, first fan 12a positioned and configured to move the air (e.g., return air 16r, which becomes supply air 16s) through cooling coil 15e and to space 11, first electrical motor 13a connected to and configured to turn first fan 12a, and a first variable-speed drive unit or system 15 configured and at least electrically connected to drive the first electrical motor 13a.

In this particular embodiment, air conditioning unit 10 or system 10s also includes a first sensor positioned and configured to sense a first condition within at least one of the space 11 and the air (e.g., return air 16r). In various embodiments, the first condition comprises a humidity, for example, within space 11 or of return air 16r. Two examples of such a first sensor include sensor 14b and sensor 14d shown in FIG. 1. Different embodiments of the invention may include sensor 14b, sensor 14d, or both, for example. Sensor 14b may be a humidity sensor located within space 11 within enclosure or building 19, and sensor 14d may be a humidity sensor located within return air 16r drawn from space 11 via duct 16b. Other embodiments may measure humidity at another location, for example, within supply air 16s (e.g., downstream of evaporator or cooling coil 15e, for instance, at the location represented by sensor 14e). Such a humidity may be an indicator of moisture content within the air, and may be a relative humidity, an absolute humidity, a dew point, or the like, as examples. Sensor 14b, 14d, or both, may be an electronic device, which may output an electrical signal that represents or indicates such a humidity, for example. In certain embodiments, sensor 14b, 14d, or both, may be part of a greater device, which may measure other parameters, input other values, perform other functions, or the like. For example, humidity sensor 14b may be part of thermostat 14t located within space 11 or building 19.

Various embodiments of air conditioning unit 10 or system 10s also include a second sensor positioned and configured to sense a second condition, which may specifically be at the cooling coil 15e. In a number of embodiments, this second condition may be the formation of frost on cooling coil 15e, for example, or may be a condition wherein frost formation is possible or likely to occur or to have occurred. In some embodiments, the second condition is a temperature, for example, of (or at) cooling coil 15e (e.g., measured with temperature sensor 14f) or a temperature of supply air 16s (e.g., measured with sensor 14e downstream of cooling coil 15e). A temperature may be measured (e.g., with sensor 14f or at other locations), using a resistive thermal device (RTD) a thermocouple, a bulb containing a fluid that expands and contracts with changing temperature, etc.

In various embodiments, the temperature at cooling coil 15e, may be measured in a manner such that the temperature of cooling coil 15e is measured directly (e.g., with the temperature sensor insulated from the nearby air), by measuring the temperature of air (e.g., supply air 16s adjacent to the cooling coil 15e), or the temperature sensor may be positioned (e.g., in contact with or adjacent to and downstream from evaporator 15e) such that the temperature measurement is influenced by the temperatures of both the cooling coil 15e and the air. In some embodiments, an infrared detector or thermal imager may be used (e.g., as sensor 14d, 14e, or both), for example, to detect changes in surface temperature (e.g., of cooling coil 15e, for instance, resulting from insulating properties of frost formed on cooling coil 15e).

In other embodiments, the second condition may be another indicator of frost formation on cooling coil 15e. For example, the second condition may be an increase in pressure drop across cooling coil 15e (e.g., where frost may block flow of air 16r or 16s through cooling coil 15e), for instance, measured as a differential pressure between pressure sensors 14d and 14e, for example, at a constant or common speed of fan 12a or motor 13a. In some embodiments, an absolute or gauge pressure may be used, (e.g., at sensor 14d or 14e) instead of a measured (or calculated) differential pressure. In other embodiments, pressure drop (e.g., across coil 15e) may be detected from current, power, voltage, speed, or a combination thereof, of motor 13, fan 12a, drive unit 15, or a combination thereof. In still other embodiments, the second condition may be frost formation on evaporator 15e detected with an optical sensor, (e.g., at sensor 14d or 14e) which may detect a change in emissivity, or reflectivity of cooling coil 15e as (e.g., white) frost forms thereon, for example.

In other embodiments, actual frost formation may be detected with a second sensor that detects the electrical insulating or heat insulating (or conducting) properties of the frost, detects the physical presence or thickness of the frost, detects a change in sound, vibration or resonance produced by the frost, detects the weight of the frost, or the like. In even other embodiments, the second condition may be detected by measuring the temperature or phase of refrigerant leaving cooling coil 15e, by measuring or detecting the pressure of the refrigerant, or by changing (e.g., interrupting) the flow of refrigerant or by changing (e.g., increasing) the speed of fan 12a and observing a response, (e.g., a change in temperature of evaporator 15e, supply air 16s, or both, where the presence of frost on evaporator 15e may cause it to warm more slowly or stay cold longer as the frost melts). In some embodiments, the first condition (e.g., humidity), the second condition (e.g., frost formation on evaporator 15e), or both, may be detected by measuring the flow rate of condensation produced from evaporator 15e, as further examples.

Various such embodiments include controller 14 that is in communication with the first variable-speed drive unit or system 15 and in communication with the first sensor and the second sensor, for example. In many such embodiments, controller 14 is configured to cause the first variable-speed drive system 15 to change the speed of the first electrical motor 13a in response to the first condition sensed by the first sensor and in response to the second condition sensed by the second sensor. It should be noted that, in the embodiment illustrated, the variable-speed drive system 15 is a separate component from motor 13a, but in other embodiments the variable-speed drive system 15 may be physically attached to or integral with motor 13a.

In a number of embodiments, controller 14 is configured to cause the first variable-speed drive system 15 to reduce the speed of the first electrical motor 13a in response to an excessive humidity condition sensed by the first sensor (e.g., within space 11, return air 16r, or supply air 16s). Reducing the speed of motor 13a, and thereby fan 12a, reduces the airflow rate through cooling coil 15e causing cooling coil 15e and the air passing therethrough (e.g., supply air 16s) to become colder. Colder air is less able to retain moisture or humidity, so the moisture in the air condenses (e.g., onto cooling coil 15e, where it may be collected for disposal). In many embodiments, if cooling coil 15e becomes too cold (e.g., drops below freezing) then frost may form on cooling coil 15e rather than liquid water, or liquid water condensation may freeze forming ice on cooling coil 15e. (As used herein, unless clearly otherwise, “frost” formed, for example, on cooling coil 15e includes “ice” formed on cooling coil 15e via freezing of liquid water that has condensed on cooling coil 15e and then frozen.) Frost formation on cooling coil 15e may reduce the heat transfer effectiveness of cooling coil 15e, block the flow of air (e.g., return air 16r) through cooling coil 15e, cause structural damage to cooling coil 15e or other parts of air conditioning unit 10 or system 10s, cause condensation to leak or travel to an undesired location, potentially damaging other components or materials, or a combination thereof, as examples.

In some embodiments, for example, to avoid frost formation or accumulation, controller 14 is configured to cause the variable-speed drive system 15 to stop reducing the speed of the first electrical motor 13a. Further, in some embodiments, the controller 14 is configured to cause the first variable-speed drive system 15 to actually increase the speed of the first electrical motor 13a to avoid frost formation on the cooling coil 15e. Such activities are described in more detail below. As used herein, avoiding frost formation includes preventing frost from forming at all, as well as reducing the amount of frost that forms, for example, in comparison with the amount of frost that would form (or would have formed) if action to avoid frost formation had not been taken.

Still further, some embodiments include a third sensor positioned and configured to sense a third condition within at least one of the space 11 and the air (e.g., return air 16r or supply air 16s), and this third condition may be a temperature within at least one of the space 11 and the air (e.g., return air 16r or supply air 16s), for example. One or more of sensors 14c, 14d, and 14e, may be an example of this third sensor. Sensor 14c is shown within thermostat 14t, and may be the same temperature sensor that is used to control the temperature of space 11. In the embodiment illustrated, thermostat 14t is an example of a system controller located within space 11. As used herein, a system controller may be a thermostat, a setback controller, or another device into which a user can input instructions for how unit 10 or system 10s is to operate. As illustrated, in some embodiments, a system controller (or thermostat) may include temperature sensor 14c, humidity sensor 14b, or both. Sensor 14d is within return air 16r, and sensor 14e is within supply air 16s, and sensors 14d, 14e, or both, may be (or include) temperature sensors (e.g., the third sensor described herein).

In some such embodiments, the controller 14 is in communication with the third sensor and is further configured to forgo causing the first variable-speed drive system 15 to reduce the speed of the first electrical motor 13a in response to the first condition sensed by the first sensor, if the third condition exceeds a threshold. Controller 14 may be configured as such through software instructions, for example. In certain embodiments, the threshold is a temperature, which may be relative to a temperature set point of the system controller (e.g., thermostat 14t). In certain embodiments, the threshold may be 2, 3, 4, 5, 7, 8, 9, 10, 11, 12, 15, or 20 degrees (F or C) above the temperature set point (e.g., of thermostat 14t), for example. Thus, if the temperature (e.g., within space 11 or return air 16r) exceeds the threshold, priority may be given to cooling space 11 rather than dehumidifying space 11. In other words, the system may be programmed or configured not to go into a dehumidification mode if the temperature exceeds the threshold temperature.

In addition to the air conditioning systems and units, and controllers configured as described herein, other specific embodiments of the invention include various methods, including methods of controlling humidity within a space, methods of controlling an air conditioning unit, methods of reducing humidity, methods of reducing humidity while avoiding freezing of a cooling coil, methods of controlling the speed of a blower fan, and the like. FIG. 2 illustrates an example of a method, method 20, which may be a method of controlling humidity within a space such as space 11, but also illustrates other methods in accordance with the invention. Method 20 may be performed by air-handling or air conditioning unit 10, ventilation or air conditioning system 10s, or specifically by controller 14, as examples. In such examples, the airflow rate that is controlled may be the airflow rate of supply air 16s, return air 16r, or both, for example. In many embodiments, method 20 is automated, is computer controlled, or both. Further, in various embodiments, method 20 is repeated a number of times, is continuous, or both. And in some embodiments of method 20, humidity may be at least partially controlled, for example, in comparison with the prior art.

In the embodiment illustrated, method 20 includes providing or obtaining equipment (act or activity 21). For example, some embodiments include (at least) providing or obtaining an air-conditioning unit (e.g., 10) that includes a cooling coil (e.g., 15e) and a variable-speed fan (e.g., 12a). In many embodiments, the fan (e.g., 12a) is positioned and configured to move air (e.g., return air 16r, which becomes supply air 16s) through the cooling coil (e.g., 15e) to the space (e.g., 11). FIG. 1 illustrates an example of such equipment. In a number of embodiments, the equipment (e.g., motor 13a, compressor 17a and motor 13c, or a combination thereof) may initially, or at other times, be turned off (activity 22). In some embodiments, equipment may cycle on (e.g., in activity 26) and off (e.g., in activity 22) to control temperature within space 11, for instance. On the other hand, in other embodiments, speed, for example, of compressor 17a, fan 12a, or both, may be varied (e.g., in activity 26, activities 25 and 26, or in activities instead of some or all of activities 22, 25 and 26) to control the temperature within space 11, besides embodiments wherein the equipment cycles on and off (e.g., off in activities 26 and 22).

In various embodiments, for example, a temperature control routine (e.g., an example of which is represented by activities 22 to 27) operates to control temperature, unless conditions are such that a humidity control routine (an example of which is represented by activities 28 to 33) is allowed to take over and to reduce humidity (e.g., within space 11). In other embodiments, other routines to control temperature may be used, such as variable capacity, variable speed, proportional control, variable air volume, or a combination thereof, as examples. In some embodiments, when the humidity control routine (an example of which is represented by activities 28 to 33) is not active, or is terminated due to a change in conditions (e.g., an increase in temperature or a reduction in humidity), then the system returns to the temperature control routine (e.g., as represented by activities 22 to 27), which in some embodiments, includes an increase in fan speed (e.g., fan 12a). In different embodiments, such an increase in fan speed may be sudden, or may be gradual (e.g., incremental).

In many embodiments, a user (e.g., a person) enters or selects a temperature set point, for example, by setting a thermostat (e.g., thermostat 14t) or by entering a value into a system controller. Such a set point may be received by the equipment or controller (activity 23), for example, by thermostat 14t, controller 14, or both. Such a temperature set point (e.g., received in activity 23) may be a particular temperature, for example, in degrees F. (Fahrenheit) or C. (Centigrade or Celsius), for example, such as 72 or 75 degrees F. In some embodiments, the set point temperature may be stored, for example, in controller 14. In some embodiments, the temperature set point may be substantially constant, for example, throughout a particular day, and may remain constant once set by a user until the user changes the set point or enters a new set point. In some embodiments, on the other hand, the temperature set point may change, for example, throughout a particular day, for instance, to reduce energy consumption when occupants are not usually present, to provide different temperatures at night than in the daytime, to reduce peak energy consumption at peak demand times, to reduce electric bills where a demand charge is paid, to reduce electric bills where a higher rate is paid during high-demand times, or a combination thereof, or the like. Thus, in some embodiments, the temperature set point may be received (e.g., in activity 23) from storage, from a database, from another control device, from a formula or calculation, or the like, besides a direct entry from a user entered at the time of the change.

In various embodiments, a temperature within the space may be measured (activity 24). In many embodiments, measurements described herein may be made automatically, continuously, or both, for example, using sensors (e.g., 14b to 14f), under the control of a controller (e.g., controller 14), or both. In particular embodiments, for example, controller 14 or thermostat 14t may measure temperature (e.g., an example of activity 24) within space 11 using sensor 14c, for instance. In different embodiments, temperature may be measured (e.g., in activity 24) continuously, or in one or more discrete operations, for example.

In this embodiment, method 20 includes evaluating (activity 25) whether the temperature (e.g., measured in activity 24) exceeds the temperature set point (e.g., received in activity 23). If not, then the equipment (e.g., motors 13a, 13b, and 13c shown in FIG. 1) is (are) turned off (activity 22) or remain(s) off if already off, in some embodiments. On the other hand, if the temperature exceeds the set point (activity 25) then the equipment may be started, or may continue to operate if already operating (activity 26). For example, motors 13a, 13b, and 13c may be started or may be allowed to continue to run. In some embodiments, motors 13c and 13b driving the compressor 17a and the condenser fan 12b may be started first, and motor 13a driving blower fan 12a may be started after a short delay or after cooling coil or evaporator 15e becomes cool, for example, as determined by sensor 14f and controlled by controller 14. In some embodiments, equipment may operate (activity 26) for a discrete period of time, or a minimum period of time, for example, for 10, 15, 30, 45, 60, 90, 120, 150, 180, 240, or 300 seconds, as examples.

As mentioned, method 20 may be a method that includes a temperature control routine in which the unit (e.g., 10) cycles on and off to control temperature (e.g., within space 11). Other embodiments may include a temperature control routine that varies one or more speeds, for example, of motor 13c and compressor 17a, to control temperature, to control airflow, or both. In some such embodiments, speeds of motors 13a, 13b, or both, may be varied as well as motor 13c, for instance. Temperatures may be controlled or the acts or activities described to this point for method 20 may be in accordance with one of several different temperature control routines or methods known in the art.

In some embodiments of temperature control routines of method 20, a temperature deadband may be used (e.g., in activity 25). For example, in some embodiments, a two-degree temperature deadband is used, and the unit (e.g., 10) may be started (e.g., activity 26) when the temperature in the space (e.g., 11) reaches a temperature of 1 degree (e.g., F. or C.) above the temperature set point (e.g., received in activity 23), and the unit (e.g., 10) may be stopped (activity 22) when the temperature in the space (e.g., 11) reaches a temperature that is 1 degree below the temperature set point (e.g., received in activity 23). Other deadbands, for example, one half of one degree, or two degrees (F. or C.), may be used in other embodiments. While within in the deadband, the unit (e.g., 10) may remain off or operating, depending on what it was already doing, remaining in the same status to reduce the number of starts and stops of the unit (e.g., 10).

Many embodiments of the invention may include or utilize a threshold or an offset temperature (e.g., in addition to a temperature control routine), which may be evaluated in activity 27. In some embodiments, the offset temperature may be a particular number of degrees above the set point temperature (e.g., received in activity 23), for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 15, 20, or 25 degrees (F. or C.) above the set point temperature. In some embodiments, the offset temperature may be a fixed offset or threshold, while in other embodiments, the offset temperature may be selectable by the user, for example, entered into a system controller (e.g., thermostat 14t), for instance, as an absolute temperature (e.g., of space 11, for example, as measured by sensor 14c) or relative to the temperature set point (e.g., received in activity 23).

In some embodiments, if the temperature (e.g., within space 11, for instance, as measured by sensor 14c or 14d) exceeds the offset (e.g., as determined in activity 27), then the temperature control routine may continue to be followed (e.g., rather than starting a humidity control routine) to maximize effective temperature control. In some embodiments, for example, the equipment may continue to operate (e.g., repeating activity 26, for example, in the same mode or the same or higher fan speed) until the temperature (e.g., of space 11) drops below the offset temperature. In a number of embodiments, if the temperature (e.g., of space 11) exceeds the offset (e.g., as determined in activity 27), then the system (e.g., 10s) or unit (e.g., 10) may give priority to reducing the temperature (e.g., of space 11) rather than reducing humidity (e.g., rather than entering or remaining in a dehumidification mode). In some embodiments, at least if humidity is excessive, fan speeds (e.g., fan 12a) may be higher if the temperature (e.g., within space 11) exceeds the offset. In other embodiments, however, activity 27 may be omitted or skipped.

In certain embodiments, the blower (e.g., fan 12a), compressor (e.g., 17a), or both, may be started (e.g., in activity 26) at full speed. In such embodiments (e.g., of method 20), if the temperature exceeds the offset (e.g., as determined in activity 27), then the equipment (e.g., fan 12a, compressor 17a, or both), may continue to be operated (activity 26) at the full speed. In other embodiments, the blower (e.g., fan 12a) may be started (e.g., in activity 26) at less than full speed, for example, at 30, 40, 50, 60, 70, 80, or 90 percent of full speed. In such embodiments (e.g., of method 20), if the temperature exceeds the offset (e.g., as determined in activity 27), then the fan speed (e.g., fan 12a) may be increased (e.g., in activity 26, 33, or another activity), and the fan (e.g., fan 12a) may be operated (e.g., in activity 26) at a higher speed or at the full speed, as examples.

In some embodiments, the fan speed (e.g., fan 12a) may be increased (e.g., in activity 26) immediately to full speed. In other embodiments, the fan speed (e.g., fan 12a) may be increased (e.g., in activity 33) gradually or incrementally, for example, by 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15, 20, 25, 30, 40, or 50 percent of full speed or percent of the difference between the current speed and the full speed. In other embodiments, the speed (e.g., of fan 12a) may be increased continuously, for example, until full speed is reached, until the temperature (e.g., within space 11) no longer exceeds the offset (e.g., in activity 27), or until the temperature control routine calls for maintaining the same speed or reducing the speed. In some embodiments, the compressor (e.g., 17a) may also initially be started at less than full speed, and its speed may be increased if the temperature (e.g., within space 11) exceeds the offset temperature (e.g., in activity 27).

In various embodiments, if the temperature (e.g., of space 11, for example, as measured in activity 24) exceeds the set point (e.g., as determined in activity 25) but is within the off set (e.g., as determined in activity 27), then the humidity may be measured (activity 28). In some embodiments, humidity may be measured (activity 28) just if these conditions exist, while in other embodiments, humidity may be measured (activity 28) continuously or periodically, and such measurements may be used or acted upon (e.g., in a humidity control routine) only under certain conditions, such as those described herein or illustrated by method 20 or FIG. 2. In activity 28, humidity may be measured, for example, using one or more of sensors 14b, 14d, or (in particular embodiments) 14e, for example, within space 11, return air 16r, or (in particular embodiments) supply air 16s. Absolute moisture content or humidity, relative humidity, dew point, another indicia of humidity, or the like, may be measured (e.g., in activity 28) or calculated, as examples.

In the embodiment illustrated, as part of an example of a humidity-control routine, method 20 also includes evaluating whether the humidity level (e.g., measured in activity 28) is excessive (activity 29). For example, the humidity level of the space (e.g., 11) or return air (e.g., 16r) may be considered to be excessive (e.g., in activity 29) if it is a relative humidity that exceeds 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75 or 80 percent, as examples. In particular embodiments, a relative humidity between 45 and 65 percent is used (e.g., in activity 29), between 40 and 60 percent, between 50 and 60 percent, or 55 percent specifically, for instance. In other embodiments, an absolute humidity, moisture content, or wet bulb temperature may be used (e.g., in activity 29 or in a humidity-control routine) rather than (or in addition to) a relative humidity. In embodiments wherein humidity is used (e.g., in activity 29), an actual value of humidity (e.g., relative humidity) may be measured (e.g., in activity 28), which may be compared to a humidity threshold (e.g., in activity 29), for example, digitally. In some such embodiments, a user may be able to adjust or select the humidity threshold, for example, through a system controller or thermostat (e.g., 14t). In some embodiments, a user may be able to select the humidity threshold, for instance, between 40 and 60 percent. In other embodiments, a sensor (e.g., 14b or 14d) may only indicate whether the threshold humidity is exceeded or not. In such embodiments, the threshold humidity may not be adjustable, or may only be adjustable by making an adjustment at the sensor, as examples.

As an example of a humidity-control routine, in a number of embodiments, method 20 includes measuring humidity (activity 28) using an automated process to obtain a humidity measurement, and using an automated process, using the humidity measurement (e.g., from activity 28) to determine (e.g., in activity 29) whether to reduce the humidity (e.g., in supply air 16s, or space 11). In the embodiment illustrated, if the humidity is not excessive (e.g., as determined in activity 29), then if the temperature (e.g., within space 11) continues to exceed the set point (e.g., as determined in activity 25), then the equipment continues to operate (activity 26), for example, at the same fan speed (e.g., fan 12a). In some embodiments, if the fan is not already operating at full speed, or at normal speed, or if the fan speed has been reduced to reduce humidity, (e.g., as will be described below), then the fan speed (e.g., fan 12a) may be increased (e.g., in activity 26) after it is determined (e.g., in activity 29) that the humidity is not excessive.

Still referring to FIG. 2, in this example of a humidity-control routine, if the humidity level is found to be excessive (in activity 29), then the next act in the embodiment illustrated is to check the cooling coil (activity 30). As with other measurements described herein, in some embodiments, the cooling coil may be checked (activity 30) just at the time indicated, while in other embodiments, the cooling coil may be checked (activity 30) continuously or periodically, and the measurements or results of such checks may be used or acted upon only under certain conditions, such as those described herein or illustrated by method 20 or FIG. 2. In activity 30, the cooling coil (e.g., 15e) may be checked for example, using one or more of sensors 14d, 14e, or (in many embodiments) 14f, for instance. In some embodiments, a condition (e.g., a second condition) at the cooling coil (e.g., 15e) may be sensed or measured. In a number of embodiments, such a condition may be an indicator of frost formation on the cooling coil (e.g., 15e) or an indicator that conditions exist wherein frost formation could or is likely to occur, as examples. Various examples of this second condition, and how they are sensed or measured are described herein, which provide a number of examples of systems and methods of checking the cooling coil (activity 30).

In various embodiments, in the humidity-control routine, a determination is made (activity 31) whether the cooling coil (e.g., 15e) is frozen or whether conditions occur wherein freezing (e.g., of cooling coil 15e) or frost formation thereon has occurred or is likely to occur. The various decision acts or activities described herein (e.g., activities 25, 27, 29, 31, or a combination thereof) may be performed by a controller, such as controller 14, for example, which may be a digital controller, for instance. Activity 31 may be performed, for example, using information obtained, measured, or sensed in activity 30. If the cooling coil (e.g., 15e) has frozen, has frost formed on it, or has dropped below a certain temperature, as examples, (e.g., as determined in activity 31), in different embodiments, then the fan speed (e.g., fan 12a) may be increased (activity 33), for instance, to avoid further frost formation or to melt frost that has formed. On the other hand, if the cooling coil (e.g., 15e) has not frozen, does not have frost formed on it, or is above the certain temperature (or above a deadband temperature range), as examples, (e.g., as determined in activity 31) then the fan speed (e.g., fan 12a) may be reduced (activity 32), for instance, so that the temperature of the cooling coil (e.g., 15e), supply air (e.g., 16s), or both, will decrease, resulting in removal of more moisture from the supply air (e.g., 16s) or resulting in supply air (e.g., 16s) having less moisture content.

The reduction of the blower or fan speed (e.g., fan 12a) may mark the entering of a dehumidification mode, for instance, of air conditioning unit 10 or system 10s. In some embodiments, the fan speed (e.g., fan 12a) may be decreased (e.g., in activity 32) gradually or incrementally, for example, by 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15, 20, 25, 30, 40, or 50 percent of full speed or of the current speed (e.g., for each iteration of activity 32). In various embodiments, the temperature (e.g., within space 11) may be measured again (activity 24) and compared to the set point (e.g., in activity 25, and the set point may have been changed in activity 23, for example, by the operator), and the fan (e.g., fan 12a) may operate (e.g., in activity 26) at the new (reduced) speed (e.g., for a period of time, such as described herein). After this, the temperature (e.g., measured in activity 24) may be compared again against the offset (e.g., activity 27), and if it is within the offset, then the humidity may be measured (e.g., in activity 28) again, and evaluated (e.g., in activity 29). And if the humidity is still excessive (e.g., as determined in activity 29) the cooling coil may be checked again (e.g., in activity 30), and if the cooling coil (e.g., 15e) is still not frozen (e.g., as determined in activity 31), then the fan speed (e.g., of fan 12) may be reduced further (e.g., in another iteration of activity 32).

This process may repeat, for example, in the humidity-control routine, until frost conditions have occurred (e.g., as determined in activity 31) or until the temperature set point is reached (e.g., as determined in activity 25). Further, a number of methods include using an automated process, measuring a first temperature within the space (e.g., activity 24), and the reducing of the speed of the fan (e.g., activity 32) is performed only if the first temperature is below a first threshold temperature (e.g., determined in activity 27). In other embodiments, the speed (e.g., of fan 12a) may be decreased continuously, for example, gradually, for instance, until frost conditions have occurred (e.g., as determined in activity 31) or until the temperature set point is reached (e.g., as determined in activity 25).

Such a process may be automated, for example, using a digital or analogue controller (e.g., controller 14). Such methods include (e.g., using an automated process), dependent upon the humidity measurement (e.g., measured in activity 28), lowering the speed of the fan (e.g., in activity 32) to decrease the cooling coil (e.g., 15e) temperature, thus increasing the latent component of energy absorption at the cooling coil (e.g., 15e), resulting in a reduction of the humidity (e.g., in space 11) relative to or in comparison with a humidity level that would have resulted from not lowering the speed of the fan (e.g., 12a). Further, method 20 also illustrates an example of a method of, using an automated process, measuring a second condition (e.g., in activity 30) at the cooling coil, and using an automated process, controlling the speed (e.g., in activities 32, 33, or both) of the fan (e.g., fan 12a) using the second condition (e.g., measured or sensed in activity 30) to avoid frost formation (e.g., as determined in activity 31) on the cooling coil (e.g., 15e).

Certain methods include repeating, at least a plurality of times, the lowering of the speed of the fan (activity 32), which may be performed in discrete increments (e.g., in iteration s of activity 32), and the speed of the fan (e.g., 12a) may be held substantially constant for a period of time for each of the distinct increments (e.g., in activity 26). In some embodiments, the temperature of the cooling coil is measured (e.g., in activity 30) during each period of time, and the lowering of the speed of the fan (activity 32) is performed in a subsequent discrete increment only if the temperature of the cooling coil (e.g., measured in activity 30) is above a first temperature threshold (e.g., as determined in activity 31). Even further, some embodiments further include raising of the speed of the fan (activity 33), which may be performed in discrete increments (e.g., in iterations of activity 33), and the speed of the fan may be held substantially constant for a period of time for each of the distinct increments (e.g., in activity 26). In some such embodiments, the temperature of the cooling coil (e.g., 15e) is measured (e.g., in activity 30) during each period of time, and the raising of the speed of the fan (activity 33) is performed in a subsequent discrete increment only if the temperature of the cooling coil (e.g., measured in activity 30) is below a second temperature threshold.

In particular embodiments, as an example, the second condition that is checked in activity 30, for example, is a temperature at (or of) the cooling coil (e.g., of coil 15e, which may be sensed by sensor 14f, for instance). In some embodiments, the speed of the fan (e.g., 12a) is controlled (e.g., by controller 14) using the second temperature (e.g., of the cooling coil, for instance, measured or sensed in activity 30) to avoid having the second temperature drop below freezing (e.g., below 32 degrees F. or 0 degrees C., although in some embodiments, to account for variations in temperature within coil 15e, a higher temperature may be used, for example, 33, 34, 35, 36, 37, 38, or 40 degrees F., or 1, 2, 3, 4, or 5 degrees C.).

In particular embodiments, for example, the cooling coil (e.g., 15e) is determined (e.g., in activity 31) to not be frozen, or to be above freezing, if the temperature of the cooling coil (e.g., 15e) is 35 degrees F. or above. If that is the case (e.g., as determined in activity 31), then the blower speed (e.g., fan 12a) is reduced (e.g., in activity 32) by 5 percent of the full or maximum blower speed (e.g., of fan 12a or motor 13a). On the other hand, in this embodiment, the cooling coil (e.g., 15e) is determined (e.g., in activity 31) to be frozen, below freezing, or too cold, if the temperature of the cooling coil (e.g., 15e) is less than 33 degrees F. If that is the case (e.g., as determined in activity 31), then the blower speed (e.g., fan 12a) is increased (e.g., in activity 33), in this embodiment, by 5 percent of the full or maximum blower speed (e.g., of fan 12a or motor 13a). In this embodiment, if the cooling coil (e.g., 15e) is determined (e.g., in activity 31) to be less than 35 degrees, but 33 degrees or more (F.), then the blower speed (e.g., fan 12a) is neither increased (e.g., in activity 33) or decreased (e.g., in activity 32), but rather, is held the same.

The speed of the compressor (e.g., compressor 17a, driven by motor 13c), and the speed of the condenser fan (e.g., fan 12b driven by motor 13b) remain constant or at maximum during this process, in this embodiment. Also in this embodiment, at each fan speed (e.g., fan 12a, for example, obtained as a result of activities 32 or 33) the fan (e.g., 12a) operates (e.g., in activity 26) for 30 seconds, or longer, for example, if the cooling coil (e.g., 15e) is determined (e.g., in activity 31) to be less than 35 degrees, but 33 degrees or more (F.). Further, in other embodiments, other parameters may be used. For example, for the first threshold temperature, instead of 35 degrees F., 40, 38, 36, or 34 degrees F. may be used, or 6, 5, 4, 3, 2, or 1 degrees C. For another example, for the second threshold temperature, instead of 33 degrees F. in the above example, 35, 34, 32, 31, or 30 degrees F. may be used, or 2, 1, 0, −1, or −2 degrees C. may be used. Further, for the time interval, instead of 30 seconds, 10, 15, 20, 25, 35, 40, 45, 60, 75, 90, 120, 150, 180, or 240 seconds may be used in other embodiments.

In some embodiments, if the blower (e.g., fan 12a) is operated at a reduced speed (e.g., in the dehumidification mode) for a (first) period of time to reduce humidity, then the blower speed may be increased for a (second) period of time to provide for adequate mixing of the air (e.g., within space 11). In some embodiments, the first period of time (e.g., the dehumidification mode), the second period of time, or both, may include one or more iterations of activity 26, for instance. For example, in some embodiments, if the blower (e.g., fan 12a) is operated at a reduced speed (e.g., less than 50 percent of normal or full speed) for ten (10) minutes (e.g., in the dehumidification mode), then the blower speed may be increased to normal or full speed for five (5) minutes to provide for adequate mixing of the air (e.g., within space 11 or building 19). In other embodiments, the first time period (e.g., of the dehumidification mode) may be 5, 8, 12, 15, 20, or 30 minutes, and the second time period may be 1, 2, 3, 4, 6, 7, 8, 10, 12, or 15 minutes, as other examples. Further, in other embodiments, the threshold speed (e.g., instead of 50 percent) may be 25, 30, 35, 40, 45, 55, 60, 65, 70, 75, 80, 85, or 90 percent of normal or full speed, as other examples.

In different embodiments, the speed of the blower (e.g., fan 12a) may be increased suddenly to the normal or full speed (e.g., at the end of the dehumidification mode or when exiting the humidity-control routine), or may be increased gradually or in increments (e.g., such as through activity 33 described herein). In a number of such embodiments, after the second period of time, the system may return to a reduced speed (e.g., to the dehumidification mode) for another first period of time, for example, if the humidity (e.g., measured in activity 28 and evaluated in activity 29) remains excessive and the temperature (e.g., measured in activity 24) remains above the set point (e.g., received in activity 23 and compared to the temperature in activity 25). For example, the speed (e.g., of fan 12a) may be reduced again in one or more iterations of activity 32 or according to method 20 described herein, as examples.

In some embodiments, in addition to mixing the air (e.g., within space 11), periodically increasing the speed (e.g., of fan 12a) to normal or full speed (or to another higher speed) may remove some or all frost or ice from the cooling coil (e.g., 15e). Thus, in some embodiments where this occurs, activities 30 and 31 of checking the cooling coil and increasing the fan speed if freezing exists, may not be necessary. In other embodiments, activities 30 and 31 of checking the cooling coil and increasing the fan speed if freezing exists may allow for longer activity at reduced fan speeds, and thus greater or faster reduction in humidity. In some embodiments, increasing the speed (e.g., of fan 12a) to normal or full speed (or to another higher speed) may remove any frost or ice from the cooling coil (e.g., 15e) that is not prevented by activities 30 and 31 of checking the cooling coil and increasing the fan speed if freezing exists. In other words, increasing the speed (e.g., of fan 12a) to normal or full speed (or to another higher speed) may serve as a back up for activities 30 and 31 of checking the cooling coil and increasing the fan speed if freezing exists.

Further specific embodiments of the invention include, for example, particular methods of controlling humidity within a space using an air-conditioning unit (e.g., 10). Such an air conditioning unit may include, for example, a cooling coil (e.g., 15e) and a variable-speed fan (e.g., 12a, which may include motor 13a, variable-speed drive 15, or both), and the fan (e.g., 12a) may blow air (e.g., return air 16r, which becomes supply air 16s) through the cooling coil (e.g., 15e). Such methods include (e.g., in several possible sequences) receiving a temperature set point for the space (e.g., activity 23), measuring an actual temperature within the space (e.g., activity 24), measuring an actual humidity in at least one of the space and air drawn from the space (e.g., 28), and evaluating whether the actual temperature within the space is within a predetermined offset of the temperature set point (e.g., activity 27). Such methods may also include evaluating (e.g., in activity 29) whether the actual humidity (e.g., measured in activity 28) exceeds a predetermined humidity threshold, and if, and only if, the actual temperature within the space is within the predetermined offset of the temperature set point (e.g., evaluated in activity 27), and the actual humidity (e.g., measured in activity 28) exceeds the predetermined humidity threshold (e.g., evaluated in activity 29), lowering the speed of the fan (e.g., in activity 32, e.g., of fan 12a) to reduce the humidity (e.g., within supply air 16s, space 11, or both).

Some of these methods further include monitoring at least a first condition of the cooling coil (e.g., activity 30) and increasing the speed of the fan (e.g., activity 33, e.g., of fan 12a) to avoid freezing of the cooling coil (e.g., 15e, e.g., as determined in activity 31), and in particular embodiments, the monitoring of the first condition of the cooling coil (e.g., activity 30) comprises monitoring of a temperature at the cooling coil (e.g., via sensor 14f). In addition, in a number of embodiments, the lowering of the speed of the fan (e.g., in a number of iterations of activity 32) includes (e.g., in the following order), lowering the speed by a discrete speed increment (e.g., one iteration of activity 32), operating the fan (e.g., 12a) at a substantially constant speed for a discrete increment of time (e.g., one iteration of activity 26), measuring the first condition (e.g., activity 30), and repeating the lowering of the speed by a discrete speed increment (e.g., repeating activity 32), operating of the fan (e.g., 12a) at a substantially constant speed for a discrete increment of time (e.g., repeating activity 26), and measuring of the first condition (e.g., repeating activity 30), until (e.g., as determined in activity 31) the first condition (e.g., measured or sensed in activity 30) reaches the first threshold value.

In some embodiments, the increasing of the speed of the fan (e.g., a number of iterations of activity 33) comprises increasing the speed by a discrete speed increment (e.g., one iteration of activity 33), operating the fan at a substantially constant speed for a discrete increment of time (e.g., one iteration of activity 26), measuring the first condition (e.g., activity 30), and repeating the increasing of the speed by a discrete speed increment (e.g., repeating activity 33), operating the fan at a substantially constant speed for a discrete increment of time (e.g., repeating activity 26), and measuring the first condition (e.g., repeating activity 30), until (e.g., as determined in activity 31) the first condition (e.g., measured or sensed in activity 30) reaches the second threshold value. Further, in various embodiments, the first condition includes (or is) a temperature at the first coil (e.g., measured at sensor 14f), the first threshold value is a first temperature above freezing (e.g., 33 degrees F.) and the second threshold value is a second temperature (e.g., 35 degrees F.) above the first temperature. Still further, some such methods further include increasing the speed of the fan (e.g., 12a) after a first time period (e.g., 10 minutes) to insure proper air distribution within the space (e.g., 11), and then returning after a second time period (e.g., 5 minutes) to the lowering of the speed (e.g., activity 32) of the fan (e.g., 12a) to reduce the humidity (e.g., within space 11).

Other embodiments of the invention may include other actions or aspects for example, for controlling of temperature within space 11, for example. In some embodiments, the speed, for example, of fan 12a, compressor 17a, fan 12b, or a combination thereof, may be varied to control temperature, for instance. Further, various needs, objects, benefits, other advantages, and solutions to problems have been described herein with regard to specific embodiments. However, the needs, objects, benefits, advantages, solutions to problems, and element(s) that may cause benefit, advantage, or solution to occur or become more pronounced are not to be construed as critical, required, or essential features or elements of the claims or the invention. Reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.” As used herein, the terms “comprises”, “comprising”, or a variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Further, no element described herein is required for the practice of the invention unless expressly described as “essential” or “critical”.

Claims

1. An air conditioning system for cooling and dehumidifying a space within an enclosure, the air conditioning system comprising:

a cooling coil positioned within the system and configured to cool air to be delivered from the air conditioning system to the space;

a first fan positioned and configured to move the air through the cooling coil and to the space;

a first electrical motor connected to and configured to turn the first fan;

a first variable-speed drive system configured and at least electrically connected to drive the first electrical motor;

a first sensor positioned and configured to sense a first condition within at least one of the space and the air, wherein the first condition comprises a humidity;

a second sensor positioned and configured to sense a second condition at the cooling coil; and

a controller that is in communication with the first variable-speed drive system and in communication with the first sensor and the second sensor, wherein the controller is configured to cause the first variable-speed drive system to change the speed of the first electrical motor in response to the first condition sensed by the first sensor and in response to the second condition sensed by the second sensor.

2. The air conditioning system of claim 1 wherein the controller is configured to cause the first variable-speed drive system to reduce the speed of the first electrical motor in response to an excessive humidity condition sensed by the first sensor.

3. The air conditioning system of claim 1 wherein the second condition is a temperature at the cooling coil.

4. The air conditioning system of claim 1 wherein the controller is configured to cause the first variable-speed drive system to stop reducing the speed of the first electrical motor to avoid frost formation on the cooling coil.

5. The air conditioning system of claim 1 wherein the controller is configured to cause the first variable-speed drive system to increase the speed of the first electrical motor to avoid frost formation on the cooling coil.

6. The air conditioning system of claim 1 wherein the cooling coil is an evaporator coil, and wherein the air conditioning system further comprises, within a single enclosure for the air conditioning system, an expansion valve, a compressor, an electric second motor connected to and configured to turn the compressor, a condenser coil, a second fan configured to blow air through the condenser coil, and an electric third motor connected to and configured to turn the second fan.

7. The air conditioning system of claim 1 further comprising a third sensor positioned and configured to sense a third condition within at least one of the space and the air, wherein the third condition comprises a temperature within at least one of the space and the air, and wherein the controller is in communication with the third sensor and the controller is further configured to forgo causing the first variable-speed drive system to reduce the speed of the first electrical motor in response to the first condition sensed by the first sensor, if the third condition exceeds a threshold.

8. The air conditioning system of claim 7 wherein the third sensor comprises a system controller located within the space, and the threshold is relative to a temperature set point of the system controller.

9. A building comprising the air conditioning system of claim 1, wherein the building forms the enclosure.

10. A method of controlling humidity within a space, the method comprising at least:

providing or obtaining an air-conditioning unit, the air conditioning unit comprising a cooling coil and a variable-speed fan, wherein the fan is positioned and configured to move air through the cooling coil to the space;

measuring humidity using an automated process to obtain a humidity measurement;

using an automated process, using the humidity measurement to determine whether to reduce the humidity;

using an automated process, and dependent upon the humidity measurement, lowering the speed of the fan to decrease the cooling coil temperature, thus increasing the latent component of energy absorption at the cooling coil, resulting in a reduction of the humidity relative to a humidity level that would have resulted from not lowering the speed of the fan;

using an automated process, measuring a second condition at the cooling coil; and

using an automated process, controlling the speed of the fan using the second condition to avoid frost formation on the cooling coil.

11. The method of claim 10 further comprising, using an automated process, measuring a first temperature within the space, and wherein the reducing of the speed of the fan is performed only if the first temperature is below a first threshold temperature.

12. The method of claim 10 wherein the second condition is a temperature of the cooling coil and the speed of the fan is controlled using the second temperature to avoid having the second temperature drop below freezing.

13. The method of claim 12 further comprising, repeating at least a plurality of times the lowering of the speed of the fan, wherein the lowering of the speed of the fan is performed in discrete increments, the speed of the fan is held substantially constant for a period of time for each of the distinct increments, the temperature of the cooling coil is measured during each period of time, and the lowering of the speed of the fan is performed in a subsequent discrete increment only if the temperature of the cooling coil is above a first temperature threshold.

14. The method of claim 12 further comprising, raising of the speed of the fan, wherein the raising of the speed of the fan is performed in discrete increments, the speed of the fan is held substantially constant for a period of time for each of the distinct increments, the temperature of the cooling coil is measured during each period of time, and the raising of the speed of the fan is performed in a subsequent discrete increment only if the temperature of the cooling coil is below a second temperature threshold.

15. A method of controlling humidity within a space using an air-conditioning unit, the air conditioning unit comprising a cooling coil and a variable-speed fan, wherein the fan blows air through the cooling coil, the method comprising in any order:

receiving a temperature set point for the space;

measuring an actual temperature within the space;

evaluating whether the actual temperature within the space is within a predetermined offset of the temperature set point;

measuring an actual humidity in at least one of the space and air drawn from the space; and

evaluating whether the actual humidity exceeds a predetermined humidity threshold;

if, and only if, the actual temperature within the space is within the predetermined offset of the temperature set point, and the actual humidity exceeds the predetermined humidity threshold, lowering the speed of the fan to reduce the humidity.

16. The method of claim 15 further comprising monitoring at least a first condition of the cooling coil and increasing the speed of the fan to avoid freezing of the cooling coil.

17. The method of claim 16 wherein the monitoring of the first condition of the cooling coil comprises monitoring of a temperature at the cooling coil.

18. The method of claim 16 wherein the lowering of the speed of the fan comprises in the following order, lowering the speed by a discrete speed increment, operating the fan at a substantially constant speed for a discrete increment of time, measuring the first condition, and repeating the lowering of the speed by a discrete speed increment, operating of the fan at a substantially constant speed for a discrete increment of time, and measuring of the first condition, until the first condition reaches a first threshold value.

19. The method of claim 18 wherein the increasing of the speed of the fan comprises increasing the speed by a discrete speed increment, operating the fan at a substantially constant speed for a discrete increment of time, measuring the first condition, and repeating the increasing of the speed by a discrete speed increment, operating the fan at a substantially constant speed for a discrete increment of time, and measuring the first condition, until the first condition reaches a second threshold value.

20. The method of claim 19 wherein the first condition comprises a temperature at the first coil, the first threshold value is a first temperature above freezing and the second threshold value is a second temperature above the first temperature.

21. The method of claim 15 further comprising increasing the speed of the fan after a first time period to insure proper air distribution within the space, and then returning after a second time period to the lowering of the speed of the fan to reduce the humidity.