US20150323210A1

US20150323210A1 - Uniform temperature distribution in space using a fluid mixing device

Info

Publication number: US20150323210A1
Application number: US14/272,481
Authority: US
Inventors: Sunil K. Khiani; Takeshi Sakai
Original assignee: Lennox Industries Inc
Current assignee: Lennox Industries Inc
Priority date: 2014-05-07
Filing date: 2014-05-07
Publication date: 2015-11-12

Abstract

A fluid mixing device is configured to operate in response to detected differences in measureable qualities of air within a space.

Description

BACKGROUND

1. Field of the Invention
This application is directed, in general, to heating, ventilation, and air conditioning systems (HVAC) and, more specifically, to systems and methods for creating uniform temperature within a conditioned space.
2. Description of Related Art
HVAC systems deliver conditioned air via systems of ducts and vents. Typically, vents are located close to the perimeter of the spaces they access, opening through the ceiling or floor of the space. This is an economical design with respect to minimizing the length of duct needed to route conditioned air from the HVAC unit to the spaces. Unfortunately, this is an inefficient arrangement with respect to HVAC system effectiveness.
Referring to FIG. 1, a space 100 is shown with a typical HVAC system duct configuration that includes an HVAC unit 101, a duct 102, a vent 103, a return air vent 104, a return air duct 105, and a thermostat 106. During HVAC system 101 operation, conditioned air is routed to the space 100 via the duct 101 and through vent 102 in direction A. The term ‘conditioned air’ is used in reference to all air, whether heated, cooled, or ventilation air, that is routed to a space from an HVAC system component, such as an air handling unit (AHU). Return air is routed from the space 100 back to the HVAC unit 101 through return air vent 104 and return air duct 105 in direction B.
Conditioned air entering the space 100 through the vent 103 propagates through the space 100 in directions x, y, and z and mixes with ambient air. It can take several minutes for the effect of the conditioned air to be felt in areas of the space 100 farthest from the vent 103. During this time, a temperature difference exists in the space 100, with the area closest to the vent 103 approaching the conditioned air temperature while areas distant from the vent 103 remain near ambient temperature. By the time the effect of conditioned air is felt in the areas close to x_max, y_max, z_max, the area of the space 100 closest to the vent 103 is over-conditioned.
The over-conditioning of an area of the space represents a loss of HVAC system efficiency. The HVAC system must operate for longer to achieve the desired temperature throughout the space, with some areas being conditioned beyond the desired temperature. Moreover, the temperature disparity in the space during HVAC system operation results in the desired effect of HVAC system operation not being felt by occupants in the space farthest from the vent 103 for several minutes as the conditioned air and ambient air mix. A need exists for methods of decreasing the mixing time required for conditioned air to mix evenly throughout a space.
Some known methods for decreasing the mixing time are to locate the conditioned air vent closer to the center of the conditioned space or to increase the number of conditioned air vents in the conditioned space. Both methods are unattractive due to the cost of installing additional ducting.
Another method for decreasing the mixing time is for the occupant of a space to use a desk or ceiling fan to agitate the air in the conditioned space during time of HVAC system operation. The shortcoming of this method is that it requires a person in the conditioned space to turn the fan on and off throughout the day as the HVAC system cycles on and off. Accordingly, new methods are needed to reduce mixing time to capture the full efficiency potential of HVAC units.

SUMMARY

In accordance with the present invention, a fluid mixing device is configured to operate in response to detected differences in measureable qualities of air within a space.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention and the advantages thereof, reference is now made to the following Detailed Description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is an illustration of typical HVAC system duct configuration;

FIG. 2 is a functional diagram of system components;

FIG. 3 is a sensor according to one embodiment;

FIG. 4 is a functional diagram of controller components;

FIG. 5 is a fan assembly according to one embodiment;

FIG. 6A is a flowchart of a method of controller operation according to one embodiment;

FIG. 6B is a flowchart of a method of controller operation according to one embodiment; and

FIG. 7 is an illustration of one embodiment.

DETAILED DESCRIPTION

In the following discussion, numerous specific details are set forth to provide a thorough understanding of the present invention. However, those skilled in the art will appreciate that the present invention may be practiced without such specific details. In other instances, well-known elements have been illustrated in schematic or block diagram form in order not to obscure the present invention in unnecessary detail. Additionally, for the most part, details concerning well-known features and elements have been omitted inasmuch as such details are not considered necessary to obtain a complete understanding of the present invention, and are considered to be within the understanding of persons of ordinary skill in the relevant art.
FIG. 2 is a functional diagram of system components according to one embodiment of the present invention. As shown in FIG. 2, a system of creating uniform temperature within a space may include one or more sensors 300, a controller 400, and one or more fluid mixing devices 500. In an embodiment, additional, fewer or different components may be provided. Also, in an embodiment, more than one device may be used to perform the function of a single system component. In an embodiment, multiple system components and functions may be contained within a single component. For example, the controller 400 or fluid mixing device 500 may be configured to include a sensor 300.
The system components may be utilized in a space in which the air is conditioned by an HVAC system. The HVAC system may heat, cool, or ventilate a space using any system of HVAC components and control methods comprising prior art. The HVAC system may include variable-speed components to increase system efficiency, such as variable-speed compressors, blowers, fans, and the like. The HVAC system may use control methods to improve system performance in partial load conditions, such as staging in component operation to match HVAC demand. These components and controls improve HVAC system efficiency by allowing the HVAC system to more closely match system demand and maintain conditions within the space closer to a desired setting. The details of the design and operation of high-efficiency HVAC system components are within the understanding of persons of ordinary skill in the relevant art and are omitted from this description.
The sensors 300 may measure characteristics of the air in the space 100 such as temperature, relative humidity, atmospheric pressure, and the like. The sensors 300 may connect to the controller 400. The sensors 300 may be configured to connect to the controller 400 via a wired or wireless connection.
As shown in FIG. 3, in an embodiment, the sensor 300 may be a thermistor circuit enclosed in a housing that includes one or more flanges 301, an opening 302, and a display 303. The details of thermistor circuit design and operation are considered to be within the understanding of persons of ordinary skill in the relevant art and are omitted from this description. In other embodiments, the sensor 300 may measure temperature, relative humidity, atmospheric pressure, and the like. The sensor 300 may be configured to measure some or all of these air quality characteristics. If, in a particular embodiment, the sensor 300 is configured to measure air temperature, the sensor may be configured to measure the air temperature using any known method, including the use of thermocouples, resistance temperature detection, pyrometry, infrared thermography, and the like. The sensor 300 may have a fixed location within the space 100 or may be moveable within the space 100.
The flange 301 may be part of the sensor 300 housing and are used in conjunction with a screw or nail to secure the sensor to a surface within the space 100. Other methods of securing the sensor 300 to a surface within the space 100 may be used in place of, or in addition to, the flange 301 and include the use of mounting brackets, adhesives, Velcro, magnets and the like.
The opening 302 may be part of the sensor 300. The opening 302 may allow for the sensor 300 to be configured for a wired connection to other system components. In other embodiments, the sensor 300 may be configured to connect to other system components using a wireless connection. The sensor 300 may include a display 303. The display 303 may show data such as temperature, relative humidity, air pressure, time of day, and the like.
In an embodiment, one or more sensors 300 may be used. In one embodiment, for example, a single infrared-type sensor 300 may be configured to take periodic measurements from a plurality of surfaces within the space 100. In another embodiment, for example, a plurality of sensors 300 may be placed throughout the space 100, with each sensor 300 continuously monitoring the air near it. One skilled in the relevant art will understand that increasing the number of sensors 300, or increasing the number and frequency of measurements taken by each sensor 300, will enhance the system's ability to detect differences in measurable air quality characteristics within the space 100. Alternatively, zero sensors 300 may be used. In such an embodiment, the controller 400 may be configured to operate the fluid mixing device 500 in response to HVAC system operation.
The sensor 300 may be placed anywhere within the space 100. One skilled in the relevant art will understand, however, that detection of differences in measurable air quality characteristics within the space 100 may be enhanced if the sensors 300 are configured to take measurements from points within the space 100 that are most distant from one-another. Further, the detection of an induced difference in a measurable air quality characteristic with a space 100 caused by HVAC system operation may be enhanced if the sensors 300 are configured such that at least one sensor 300 is near the vent 103 and one or more additional sensors 300 is far from vent 103.
The controller 400 operates the fluid mixing device 500 in response to measurement data received from the sensors 300. The controller 400 may be located within the space 100 or elsewhere, such as in the thermostat 106 or other controls of an HVAC system. The controller 400 is connected to the sensors 300 and the fluid mixing device 500 and may be connected to an HVAC system. The controller 400 may be configured to connect to the sensors 300 and the fluid mixing device 500 via a wired or wireless connection. As shown in FIG. 4, in an embodiment, the controller 400 may include an I/O interface 401, a memory 402, and a processor 403. The controller 400 may be implemented with hardware, software, or firmware.
The I/O interface 401 may include any operable connection. An operable connection may be one in which signals, physical communications, and/or logical communications may be sent and/or received. An operable connection may include a physical interface, an electrical interface, and/or a data interface. An operable connection may include differing combinations of interfaces and/or connections sufficient to allow operable control. For example, two entities may be operably connected to communicate signals to each other directly or through one or more intermediate entities.
Logical and/or physical communication channels may be used to create an operable connection. For example, the I/O interface 401 may include a first communication interface devoted to sending signals, data, packets, or datagrams and a second communication interface devoted to receiving signals, data, packets, or datagrams. Alternatively, the I/O interface 401 may be implemented using a single communication interface.
The memory 402 may be a volatile memory or a non-volatile memory. The memory 402 may include one or more of a read only memory (ROM), dynamic random access memory (DRAM), a static random access memory (SRAM), a programmable random access memory (PRAM), a flash memory, an electronic erasable program read only memory (EEPROM), static random access memory (RAM), or other type of memory. The memory 402 may include an optical, magnetic (hard drive) or any other form of data storage device. In one embodiment, the memory 402 may be built into the processor 403.
The memory 402 may store computer executable instructions. The processor 403 may execute computer executable instructions. The computer executable instructions may be included in computer code. The computer code may be stored in the memory 402. The computer code may be written in any computer language, such as C++, CU, Java, Pascal, Visual Basic, Perl, HyperText Markup Language (HTML), JavaScript, assembly language, extensible markup language (XML) and any combination thereof. The memory 402 is a non-transitory tangible storage media.
The computer code may be logic encoded in one or more tangible media or one or more non-transitory tangible media for execution by the processor 403. Logic encoded in one or more tangible media for execution may be defined as instructions that are executable by the processor 403 and that are provided on the computer-readable storage media, memories, or a combination thereof. Instructions for instructing a network device may be stored on any logic. Logic may include a software controlled microprocessor, an application specific integrated circuit (ASIC), an analog circuit, a digital circuit, a programmed logic device, a memory device containing instructions, and the like. The instructions may be stored on any computer readable medium, including a floppy disk, a hard disk, an ASIC, a compact disk, other optical medium, a random access memory (RAM), a read only memory (ROM), a memory chip or card, a memory stick, and other media from which a computer, a processor or other electronic device can read.
The processor 403 may include a general processor, digital signal processor, ASIC, field programmable gate array, analog circuit, digital circuit, central processing unit (CPU), micro-processor unit (MPU), micro-controller unit (MCU), combinations thereof, or other now known or later developed processor. The processor 403 may be a single device or combinations of devices, such as associated with a network or distributed processing. The processor 403 may be responsive to or operable to execute instructions stored as part of software, hardware, integrated circuits, firmware, micro-code or the like. The functions, acts, methods or tasks illustrated in the figures or described herein may be performed by the processor 403 executing instructions stored in the memory 402. The instructions are for implementing the processes, techniques, methods, or acts described herein.
The memory 402 may store a predefined function that may be used by the controller 400 to control the operation of the fluid mixing device 500 at different speed and direction settings. An input of the predefined function may be measured values from the sensors 300, and an output of the predefined function may be a speed and direction setting. In one alternative embodiment, an input of the predefined function may be the capacity at which the HVAC system is operating, and an output of the predefined function may be a speed and direction setting.
In another alternative embodiment, the predefined function may be a look-up table that includes ranges of air quality characteristic difference values between sensors 300 and corresponding fluid mixing device 500 speed and direction settings. In another embodiment, the predefined function may be an equation comparing the maximum calculated difference among the sensors 300 to a predetermined tolerance value, with the fluid mixing device being energized at a single speed and direction setting upon the tolerance value being exceeding.
The fluid mixing device 500 may be located within the space 100. The fluid mixing device 500 may connect to controller 400. The fluid mixing device 500 may be configured to connect to the controller 400 via a wired or wireless connection. One or more fluid mixing devices may be used, depending on the particular embodiment. For example, in one embodiment, in a space 100 with two ceiling fans, both ceiling fans may be configured to operate in response to controller 400.
As shown in FIG. 5, in an embodiment, the fluid mixing device 500 may be a fan configured to move the air in the space 100 in one of two directions, as desired. The fan 500 may include a plurality of blades 501 that may be rotated about a hub 502 in response to electrical input to a motor 503. In other embodiments, the fluid mixing device may be a blower assembly, or any other device employing methods of mechanical agitation or jet agitation.
The electrical input to motor 503 may be a direct current (DC) input or an alternating current (AC) input. In one embodiment, the electrical input may be a 4-wire pulse width modulated (PWM) signal that may include a power signal, a ground signal, a control signal, and a sense signal. The fan 500 may include a sensor that detects the rotation of motor 503 and produces the sense signal. The sensor may be a magnetic sensor, a mechanical sensor, an optical sensor, or the like. In one embodiment, the sensor is omitted.
The fan 500 may include a tachometer configured to detect the speed of the fan 500 from the sense signal. The sense signal may have an amplitude or frequency in proportion to the speed of fan 500. In one embodiment, the tachometer function may be incorporated into the controller 400. The speed of the fan 500 may be measured in revolutions per minute (RPM). Alternatively, the output of the tachometer may also be used to determine whether the fan 500 is moving.
The control signal may be a PWM signal in which the relative width of pulses determines the level of power applied to the motor 503. The RPM of fan 500 may have a direct relationship to the width of PWM pulses. While the control signal controls the power supplied to the motor 503, the actual power is applied by the power signal. Alternatively, the function of the power signal and the control signal are combined in a 3-wire fan, where the entire power to the fan is switched on and off, and the environmental controller 400 directly sets the amplitude of the power signal to control the speed of the fan motor. Alternatively, the speed of the fan motor may be controlled using any known methods of fan speed control.
The fluid mixing device 500 may be configured to allow for operation separate from operation of an HVAC system. For example, in an embodiment, the fluid mixing device 500 may be a fan configured to be operable regardless of whether an HVAC system is supplying conditioned air to the space 100 or not. The fluid mixing device 500 may be configured to allow for on/off and speed control independent of, and in addition to, signal input from the controller 400. For example, in an embodiment, a fan may be configured to operate in response to signal input from controller 400 as well as from one or more other methods of control, such as switches, pull chains, remote controllers, and the like.
FIG. 6A illustrates a flow chart of one method of fan control. The method is implemented in the order shown, but other orders may be used Additional, different, or fewer steps may be provided.
In step 601, a controller receives measurement data from one or more sensors within a space. The sensors may be electrically connected to the controller. The sensors may be positioned within the space. The measurement data may be a direct measure of air temperature or may be any a measure of any fluid characteristic from which a temperature value can be calculated. The sensor data received by the controller may be in a format that indicates air temperature. Alternatively, the sensor data may be in a raw sensor format, and the controller converts the raw sensor format to an air temperature value.
In step 602, the controller calculates the differences between temperature values across the space from the sensor data received. In an embodiment using only two sensors, a single difference value may be calculated. In embodiments using more than two sensors, multiple difference values may be calculated with a difference value calculation being made for each unique combination of two sensor inputs.
In step 603, the controller determines whether any difference value is greater than a tolerance value. The tolerance value may be stored in the controller memory. If the difference value is greater than the tolerance value, the controller generates a control signal to energize a fluid mixing device in step 604.
The control signal may be a PWM signal, for example, including a train of on-off pulses. The widths of the on-off pulses may determine the level of power applied to the fan with the width of the on pulses varying directly with the power applied to the fan. The controller may vary the widths of the on-pulses in response to calculated difference values to adjust the speed of the fan. Alternatively, the controller may adjust the fan speed by varying the power supplied to the fan.
The amount the control signal is configured to increase or decrease the speed of the fan may be a function of the magnitude of the calculated difference value. A predefined function may be stored in the controller. The input of the predefined function may be the calculated temperature differences and an output of the predefined function may be a speed and direction setting. In one embodiment, the predefined function may be a look-up table that includes ranges of air temperature difference values and corresponding fan speed and direction settings. In another embodiment, the predefined function may be an equation comparing the maximum calculated temperature difference to a tolerance value, with the fluid mixing device being energized at a single speed and direction setting upon the tolerance value being exceeding.
If the controller determines that the temperature difference within the space is not greater than an tolerance value in step 603, the controller will determine if the fluid mixing device is energized in step 605. If the fluid mixing device is energized at a time that the temperature difference within the space is not above tolerance, the controller will de-energize the fluid mixing device in step 606.
In the embodiment shown in FIG. 6A the controller is configured to generate the control signal for as long as a difference value above the tolerance value exists. In an alternative embodiment, the controller may be configured to generate the control signal for a predetermined length of time upon determining that a difference of greater than the tolerance value exists within the space.
FIG. 6B illustrates a flow chart of one alternative method for fan control. The method is implemented in the order shown, but other orders may be used. Additional, different, or fewer steps may be provided. The method shown in FIG. 6B may be used for static operation of system configuration that may include zero sensors. In such an embodiment, in which no sensors are used, the controller may assume that a difference in a measureable quality of the air within a space exists during HVAC system operation.
In step 610, the controller may detect whether the HVAC system is providing conditioned air to the space. The controller may also detect the capacity at which the HVAC system is operating. If the HVAC system is operating, the controller may assume that a difference in a measureable quality of the air exists within the space as caused by the HVAC system providing conditioned air to the space.
In step 611, the controller may generate a control signal to energize the fluid mixing device in response to detecting HVAC system operation. The controller may be configured to operate the fluid mixing device at a desired speed and direction.
In an embodiment, the speed and direction setting of the fluid mixing device may be the result of a predefined function which may be a look-up table that includes ranges of HVAC operating capacity values and corresponding fluid mixing device speed and direction settings. The controller may adjust the speed and direction settings of the fluid mixing device using a PWM signal as described above. Alternatively, the controller may adjust the fluid mixing device speed and direction by varying the power supplied to the fan.
If the controller determines that the HVAC system is not operating, the controller may determine whether the fluid mixing device is energized in step 612 and de-energize the fluid mixing device in step 613. In this embodiment, the controller is configured to generate the control signal only for as long as the HVAC system is providing conditioned air to the space. In an alternative embodiment, the control signal may be generated for a predetermined length of time before being de-energized upon the controller detecting conditioned air being supplied to the space by the HVAC system.
In an embodiment, as shown in FIG. 7, the described system for creating uniform temperature distribution may be used in a space 100 being heated by a modulating furnace operating at a partial load setting. The heated air may enter the space 100 at A in the direction shown. Return air may leave the space 100 at B in the direction shown. Sensors 300A and 300B may be placed within the space 100 and configured to take temperature measurements. The controller 400 may receive the temperature measurements and calculate the difference between the measurements. The controller 400 may generate a control signal to energize fan 500 if the difference value between the temperatures detected by sensors 300A and 300B is above a tolerance value, for example 2° F. The circulating blades of fan 500 may agitate the air in the space 100 to promote mixing of the heated air near A with the ambient air in the rest of the space 100. The controller may continue to generate the control signal for as long as the detected temperature difference remains above the tolerance value.
The location of each system components shown in FIG. 7 is illustrative only. Those skilled in the relevant art will appreciate that the preferred system configuration for a particular space may differ from the configuration shown in FIG. 7. The preferred system configuration, and component placement within a space, will vary with each space in accordance with a multitude of design considerations. Some considerations that may affect system configuration are cost, size and shape of the space, the level of control desired, the availability of mounting locations for components, installation difficulty, and the like.
In another embodiment, the described system for creating uniform temperature distribution may be used in a space receiving cooling air from an HVAC system. Sensors may be placed within the space and configured to measure relative humidity. The controller may be configured to generate a control signal to energize a fan in response to a difference in measured values that exceeds a tolerance value. The controller may generate the control signal for a predetermined amount of time stored in the controller memory, for example 60 seconds. The controller may then re-calculate the difference in measured values between the sensors and again compare the difference value to a tolerance value.
Having thus described the present invention by reference to certain of its preferred embodiments, it is noted that the embodiments disclosed are illustrative rather than limiting in nature and that a wide range of variations, modifications, changes, and substitutions are contemplated in the foregoing disclosure and, in some instances, some features of the present invention may be employed without a corresponding use of the other features. Many such variations and modifications may be considered desirable by those skilled in the art based upon a review of the foregoing description of preferred embodiments. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention.

Claims

1. A system for creating uniform temperature distribution within a space, comprising:

an HVAC system configured to supply conditioned air to the space;

a fluid mixing device located within the space operable separately from operating and non-operating states of the HVAC system; and

a control system configured to operate the fluid mixing device in response to a difference in a measureable quality of the air within the space, with the difference value as between the measureable quality of the air within the space at about the same time and from a plurality of locations within the space.

2. The system of claim 1, wherein the control system comprises:

one or more sensing devices configured to detect a measurable quality of the air within the space; and

a system controller configured to:

receive measurements from the sensing devices;

calculate the difference in a measureable quality of the air within the space, with the difference value calculated as between measurements taken at about the same time and from a plurality of locations within the space; and

energize the fluid mixing device when a difference of greater than a tolerance amount is indicated by measurements received from one or more sensing devises.

3. The system of claim 2, wherein the control system is operably connected to the HVAC system.

4. The system of claim 3, wherein the measurable quality of air within the space is air temperature.

5. The system of claim 3, wherein the mixing device is a fan.

6. The system of claim 2, wherein the control system is configured to operate during times when the HVAC system is supplying air to the space.

7. The system of claim 6, wherein the HVAC system is configured to supply heated air to the space.

8. The system of claim 7, wherein the mixing device is a fan.

9. A method of increasing uniform temperature distribution within a space, comprising:

providing an HVAC system;

providing conditioned air to a space from the HVAC system;

providing a fluid mixing device within the space operable separately from operating and non-operating states of the HVAC system; and

providing a control system configured to operate the fluid mixing device in response to a difference in a measureable quality of the air within the space, with the difference value as between the measureable quality of the air within the space at about the same time and from a plurality of locations within the space.

10. The method of claim 9, wherein the step of providing the fluid mixing device further comprises providing one or more fans.

11. The method of claim 9, wherein the measureable quality of air within the space is the air temperature.

12. The method of claim 9, further comprising configuring the HVAC system to operably connect to a control system configured to operate the fluid mixing device in response to a difference in a measureable quality of the air within the space, with the difference value calculated as between measurements taken at about the same time and from a plurality of locations within the space.

13. The method of claim 12, wherein the step of providing fluid mixing device further comprises providing one or more fans.

14. The method of claim 12, wherein the measureable quality of air within the space is the air temperature.

15. A method of increasing uniform temperature distribution within a space, comprising:

providing an HVAC system;

providing conditioned air to a space from the HVAC system;

providing a fluid mixing device within the space operable separately from operating and non-operating states of the HVAC system;

providing one or more sensing devices within the space configured to sense a measureable quality of the air in the space; and

providing for the fluid mixing device to be operated in response to a signal generated upon indication of a difference in a measureable quality of the air within the space, with the difference value calculated as between measurements taken by the sensing devices and at about the same time.

16. The method of claim 15, wherein the fluid mixing device is one or more fans.

17. The method of claim 15, wherein the measureable quality of air within the space is the air temperature.