US20160131391A1

US20160131391A1 - Electroactive smart hvac vent register

Info

Publication number: US20160131391A1
Application number: US14/930,525
Authority: US
Inventors: Lei He; Qibing Pei
Original assignee: University of California
Current assignee: University of California
Priority date: 2014-11-03
Filing date: 2015-11-02
Publication date: 2016-05-12

Abstract

An electroactive register is shown configured to modulate the incoming airflow in an HVAC duct to form two localized airflows: a first a high-speed airflow to form a conical air curtain surrounding an occupant and limiting air exchange between inside air and air outside of the air curtain, and a second a low-speed airflow (also referred to as center air) inside the air curtain to cool or heat the occupant comfortably. The temperature gradient between inside and outside of the air curtain enables expansion of set points of HVAC. The electroactive register is also able to improve personal comfort as the center air F_LScan be customized for each individual occupant.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to, and the benefit of, U.S. provisional patent application Ser. No. 62/074,412 filed on Nov. 3, 2014, incorporated herein by reference in its entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

INCORPORATION-BY-REFERENCE OF COMPUTER PROGRAM APPENDIX

Not Applicable

NOTICE OF MATERIAL SUBJECT TO COPYRIGHT PROTECTION

A portion of the material in this patent document is subject to copyright protection under the copyright laws of the United States and of other countries. The owner of the copyright rights has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the United States Patent and Trademark Office publicly available file or records, but otherwise reserves all copyright rights whatsoever. The copyright owner does not hereby waive any of its rights to have this patent document maintained in secrecy, including without limitation its rights pursuant to 37 C.F.R. §1.14.

BACKGROUND

1. Technical Field
This description pertains generally to HVAC airflow distribution devices, and more particularly to an electroactive smart register for HVAC airflow distribution.
2. Background Discussion
Existing means for distributing air in heating, ventilating and air conditioning systems are generally achieved through the use of conventional registers or diffusers, which are simple mechanical devices placed at the end of air ducts to spread airflow. Some registers can be manually closed to keep out dust or minimize/cut off air flow to a particular duct. Airflow out of conventional HVAC registers and diffusers cools or heats an entire room relatively uniformly. Such generalized heating can be inefficient, as energy may be spent keeping locations of a room at a certain temperature even though that a user is not present at those locations.

BRIEF SUMMARY

An aspect of the present description is an extended range (>1 m) wireless energy transfer in the form of an electroactive smart air conditioner vent register for significant energy savings in HVAC systems without sacrificing personal comfort. In a preferred embodiment, the smart register described herein modulates the airflow in an HVAC duct to form two localized airflows: (1) a high-speed airflow to form an air curtain surrounding an occupant, limiting air exchange between inside and outside of the air curtain, and (2) a low-speed airflow inside the air curtain to cool or heat the occupant comfortably with desired thermal asymmetry and fresh air rate. The temperature difference between inside and outside of the air curtain can be easily over 4° F. and thus allow for expansion of the set points of building HVAC in each direction by 4° F., resulting in an estimated 30% total building HVAC energy reduction.
In a preferred embodiment, the smart register uses flow actuation members in the form of smart materials capable of electrically induced large-strain deformation. Such smart materials may be an electroactive polymer, such as a dielectric elastomer or bistable electroactive polymer (BSEP) capable of electrically induced large-strain deformation. In one specific example, along the airflow direction, the smart register has an array of BSEP tubes. Each tube may be individually controlled in real time to be closed, opened, or partially-opened to modulate the volume of airflow. The tube can be funnel-shaped to slow down or speed up the airflow inside the tube. Therefore, the air flowing out of different tubes in the smart register may have different speeds to create an airflow curtain and achieve localized cooling/heating. The tubes can be actuated to bend in different directions (up to 60°) such that the airflow can be beamed to cover the entire room and follow the occupant moving up to 1 m/s.
Further aspects of the technology will be brought out in the following portions of the specification, wherein the detailed description is for the purpose of fully disclosing preferred embodiments of the technology without placing limitations thereon.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

The technology described herein will be more fully understood by reference to the following drawings which are for illustrative purposes only:

FIG. 1 is shows a schematic diagram of an air conditioning vent system incorporating an electroactive smart air conditioner vent register for improved personal comfort and reduced energy consumption in accordance with the present description.

FIG. 2 shows a detailed schematic view of the electroactive vent register of FIG. 1.

FIG. 3A through FIG. 3D show the air jets of FIG. 2 in closed, open, and left, right directional configurations, respectively.

FIG. 4 illustrates a schematic diagram of an exemplary component configuration of an electroactive register of FIG. 1 in accordance with the present description.

FIG. 5A shows a schematic diagram of the actuation of a bistable electroactive polymer (BSEP) through several intermediate stages.

FIG. 5B through 5D show an actual actuated BSEP through various stages.

FIGS. 6A and 6B show a configuration of a tubular BSEP actuator fabricated as a long rectangular BSEP film (FIG. 6A) and rolled into a tube (FIG. 6B).

FIG. 7 shows a simulation of the airflow temperature distribution for heating a standing occupant with the simulated electroactive register.

DETAILED DESCRIPTION

FIG. 1 shows an air conditioning vent system 10 incorporating an electroactive smart air conditioner vent register 14 for improved personal comfort and reduced energy consumption in accordance with the present description. Input cool or hot airflow F_Ifrom a conventional HVAC system may be modulated by an optional damper 16 and enters a branch duct 12. The airflow then passes electroactive register 14 mounted at the end of the duct 12 to enter a room and cool or heat the space. The optional damper 16 controls the volume of airflow F_Ibased on thermostat settings (not shown).
For purposes of this description, the term “register” is used to describe electroactive device 14. However, it is appreciated the terms “diffuser”, “register”, “vent”, and “grill” are often used interchangeably in the art for regulating or distributing airflow from an HVAC duct. Often the term “diffuser” is used for devices that distribute airflow outward in a circular fashion (e.g. from a central location in a room) and “register” and “vent” are used to describe devices that distribute airflow in two outward opposing directions (e.g. a rectangular device positioned along or near a wall). Because the electroactive device 14 of the present description may be configured, both in prefabrication configurations and in real-time actuation, in multiple forms to function as a device associated as a “register”, “diffuser”, “vent”, or “grill,” the term “register” shall herein be defined to mean a airflow device that functions as any and all of the above terms.
As shown in FIG. 1 electroactive register 14 is configured to modulate the incoming airflow F_Iin HVAC duct 12 to form two localized airflows: (1) a high-speed airflow F_HSto form a conical air curtain 20 surrounding an occupant 18, limiting air exchange between inside air 22 and air 24 outside of the air curtain 20, and (2) a low-speed airflow F_LS(also referred to as center air) inside the air curtain 20 to cool or heat the occupant 18 comfortably. The temperature gradient between inside 22 and outside 24 of the air curtain 20 enables expansion of set points of HVAC. Electroactive register 14 is also able to improve personal comfort as the center air F_LScan be customized for each individual occupant.
In a preferred configuration shown in FIG. 2, electroactive register 14 comprises an array 28 of individually controllable air jets 30 a and 30 b. In the configuration shown in FIG. 2, an outer ring of jets 30 a are configured for projecting high-speed air to form the air curtain 20, and the inner jets 30 b are configured for projecting low-speed center air F_LS.
Referring to FIG. 3A through FIG. 3D, the air jets 30 a/30 b are individually manipulable to be controlled in real-time to close (e.g. by constricting the tube 30 at a location along its length as shown in FIG. 3A), open (FIG. 3B), or partially open. Actuation of jets 30 may be affected in real time, for example to bend or otherwise change shape at varying degrees to alter their output airflow path (as seen in FIGS. 3C and 3D) and follow a user/occupant as they move through a room. Depending on the size of the air curtain 20 or type of actuation used, the jets may be able to change direction at a rate such that the air curtain 20 follows an occupant moving at a speed of 1 m/s or more.
FIG. 4 illustrates a schematic diagram of an exemplary component configuration of an electroactive register 14 in accordance with the present description. For ease of illustration, electroactive register 14 shown in FIG. 4 having a single air jet 30. However, is it appreciated that the electroactive register 14 may comprise, and preferably comprises, a plurality of individually operable jets 30 as shown in FIG. 2.
In a preferred embodiment, jet 30 comprises a smart material capable of electrically induced large-strain deformation. Preferably, the smart material may be an electroactive polymer, such as a dielectric elastomer or bistable electroactive polymer (BSEP) capable of electrically induced large-strain deformation. One exemplary BSEP is described in U.S. Pat. No. 8,237,324 which is incorporated herein by reference in its entirety.
It is appreciated that the air jets 30 to modulate air flow can be implemented by an electroactive material, as generally described herein, or by a mechanical air nozzle that that can control airflow speed and direction.
As shown in FIG. 4, air jet 30 is formed from a bistable electroactive polymer transducer for electrically actuated deformation of one or more rigid electroactive polymer members 30. The polymer 34 has a glass transition temperatures (Tg) above ambient conditions and turn into a rubbery elastomer above Tg, with a high dielectric breakdown strength in the rubbery state. The polymer 34 can be electrically deformed to various rigid shapes with maximum strain greater than 100% and as high as 400%. The actuation is made bistable by cooling below Tg to preserve the deformation. The air jet 30 forms the shape of a tube with a central aperture 36, and includes a pair of compliant electrodes 32 in contact with polymer 34, which act as a dielectric actuation mechanism to deform when a voltage bias is applied between the pair of electrodes 32. In some of the configurations, the polymer 34 comprises a dielectric elastomer comprising a shape memory polymer. The deformations of the bistable electroactive polymer 34 can be repeated rapidly for numerous cycles.
The air jets 30 are disposed within housing 54 such that the upper end of the tubes are fit into and anchored in the openings in the top plate of the housing 54. The lower end of jet tubes 30 is free to move. The register 24 may also comprise a lower filter screen (not shown) to isolate dusts and debris. The control unit 40 is connected to the electrodes 32 via individual leads for independent operation of electrodes 32. The air jets 30 preferably comprise multiple individually operable electrodes to control the shape and/or direction of the jet aperture 36. Leads 48 couple the electrodes to a control unit 40 for operating the electrodes to manipulate the air jets in one or more configurations as seen in the exemplary shapes shown in FIG. 3A through FIG. 3D.
Control unit 40 preferably comprises application software 46 that may be stored in non-transitory memory 44 for execution on processor 42 to control actuation of the electrodes 32 to manipulate the air jets 30. Application software 46 includes code configured with routines that automatically activate a certain set of electrodes 32 according to a desired trajectory and/or flow rate of the airflow F_HSor F_LS.
Control unit 40 and application software 46 may be programmed to communicate with and/or operate one or more sensors 50 or wireless communication circuitry 56 for various data exchange or gathering with an individual 18 or user device 58. For example, application software 46 may couple to a user device 58 via wireless interface 56 to receive one or more of location data or identification data of a user 18 within a proximity of the register 14, user settings for storage within memory 44, other user data such as local air temperature, relative speed (if moving), biometric data, etc.
Control unit 40 and application software 46 may be programmed to poll one or more sensors 50 to provide location data of a user 18 with respect to the register location. For example, sensors 50 my comprise IR sensors (detecting heat signals) or motion sensors to acquire location data of one or more occupants 18 within a room. With acquired location data from sensors 50, user device 58, or both, the application software can the control the one or more jets 30 to direct and adjust airflow at a trajectory configured to center the airflow curtain 20 to be centered around the occupant 18. Feedback may be acquired from the sensors 50 or wireless device 58 to further refine airflow trajectory and flow rate.
User settings may be input for use by application software 46 for loading user preferences, e.g. temperature range, airflow speed, curtain size or other device settings. Such settings may be input via a wireless device 50 (e.g. smartphone, laptop, or the like) and application software loaded on the device 50 for communicating with register 14 via communication interface 56.
Application programming 46 may further have various modes depending on the type of energy savings desired and number of room occupants as compared to number of registers 14 in a given room. For example, the register 14 may be preset to distribute air from a localized curtain to a distributed pattern depending on the number of occupants in a room.
Power 52 may be supplied to the register 14 to operate the control unit 40 via battery, energy harvesting device, AC power (e.g. 110 v, 220 v, low voltage via a transformer, etc.) or combination of the above.
In one alternative embodiment, air jets 30 may comprise one or more embedded heating elements (not shown) to warm up the airflow. When heated airflow is used for the air curtain 20, it provides warmer airflow close to the floor and helps to reduce the undesired temperature difference between an occupants head and feet.
As shown in FIG. 2, the electroactive register 14 preferably comprises of an array of BSEP tubes 30. Each of the tubes 30 can be individually controlled in real-time in a plurality of different configurations to be closed, opened, or partially-opened to adjust the volume of airflow, or be bended in different directions (up to 60°) such that the airflow can reach the entire room.
BSEP tube 30 activation generally includes two phases: a first heating phase, generally lasting about 5 seconds, and deformation phase taking lasting approximately 0.5 seconds. Because human being movement has a temporal continuity, i.e., once a person makes a move, he or she will keep moving for a while, the future movement of an individual can be predicted (and programmed in application software 46) based on the temporal continuity to pre-heat BSEP tubes and then configure them in the desired shape in approximately 0.5 seconds or less (depending on the degree of deformation). Because the curtain 20 may be configured to have a diameter larger than 1 m, a BSEP tube 30 activation of 0.5 seconds allows for the curtain to follow the occupant moving in 1 m/s or less.
As shown in FIG. 3A through FIG. 3D, the air tube 30 can be funnel-shaped to slow down or speed up the airflow inside the tube, therefore the air flowing out of different tubes may be the high-speeded air curtain 20 or low-speeded center air F_LS. Table 1 presents two register configurations in column 2 and 3 comprising of different BSEP tube 30 sizes and different funnel-shapes to achieve a similar cooling result as in Table 3 to cool the standing occupant. For the airflow in the duct 12 with velocity of as high as 6.5 m/s or as low as 1 m/s, an air curtain F_HSvelocity of 3.51-4 m/s and center air F_LSvelocity of 0.43-0.71 m/s were obtained.
It is appreciated that BSEP tubes 30 of the present description can be configured to modulate airflow temperature as well. As shown in the bold text of Table 1, heating up by the register 14 tends to happen when the airflow is fast, the outlet diameter of the aperture 36 is small enough, and also the outlet diameter is smaller than the inlet diameter of the aperture 36. In one example, the air curtain 20 temperature is 1.9° F. warmer than that of air 22 inside curtain 20. This is beneficial to heating, as the air curtain 20 in this case leads to having more warm air close to the floor to warm up feet, a desired but difficult to achieve thermal comfort using a register from a high ceiling. Such register-based heating may be further manipulated with a suitable combination of air speed, and tube 30 shape and size.
The tube 30 dimensions in Table 1 mimics the real-time activation of the BSEP aperture 36 status based on thermal needs after the electroactive register 14 has been deployed. In contrast, the register 14 may have a preconfigured structure during fabrication. For example, design parameters such as tube 30 number, size, and placement may be preconfigured for each BSEP tube 30 of the register 14. As shown in FIG. 2, inner tubes 30 b have a smaller diameter than outer tubes 30 a for promoting airflow speed variances between the curtain F_HSand center air F_LS. Fewer tubes 30 are in general preferred, as it reduces manufacturing cost. The function of the particular tube 30 generally determines the envelope for activation. For example, a tube 30 a used for the air curtain 20 may be configured with a bigger entrance but smaller exit to have a funnel effect for speeding up the airflow. In one embodiment, activation of the tube is set for only a pre-set number of configurations, e.g. activation either totally opens or closes this tube, or makes the aperture 36 exit narrow. In other words, such configuration would only allow activation to reduce the airflow volume, or speed it up.
The electroactive registers 14 may be configured for different corners in real-time operating, and stochastic optimization may be applied to obtain an overall efficient design for different corners. Application software 46 may include stochastic optimization routines for electronic circuits of controller 40, multimedia communication, and oil reservoir systems (not shown) within the electroactive register.
The compliant electrodes 32 of the present description may be comprised of nanoparticles, nanotubes, nanowires, or a mixture thereof, made of a conductive material such graphite, grapheme, single wall carbon nanotube, few wall carbon nanotube, multiwall carbon nanotube, a conducting polymer such as polypyrrole, polyaniline, polythiophene, poly(3-methylthiophene), poly(3,4-ethylenedioxythiophene), a metal such as silver, copper, aluminum, gold, nickel, stainless steel, a ceramic conductor such as indium doped tin oxide, or a mixture thereof or other suitable conductive materials available in the art.
A wide range of transducer materials and mechanisms are contemplated for the actuation mechanism of the air tubes 30. Table 2 surveys the materials that are most relevant to the electroactive register 14 air tube 30 configuration. Most of these synthetic materials excel in certain measures of performance (e.g., stress for PZT piezoelectric crystals and strain for shape memory polymers), and underperform in other measures (low efficiency and response speed for nitinol and conducting polymers).
Among electroactive polymers (EAPs), the ionic types (including ionic polymer-metal composites, conducting polymers, ionic gel) are characterized by low driving voltage, low efficiency, slow response, and the involvement of mass transport in the actuation mechanism.
Carbon nanotubes (CNTs) have unique properties in that they possess with a tensile modulus near that of diamond and a tensile strength larger than any other continuous fibers. CNT actuators can be actuated at low voltages (˜1 V) and are capable of high operating loads (26 MPa) as well as higher actuation strain rates and cycle lifetime than most other ionic actuators, as the actuation mechanism does not require ion intercalation. CNT actuators, however, suffer from poor electromechanical coupling, and are limited to small strains (<2%). Carbon nanotube aerogel sheets have recently been employed to obtain linear strains of 220% and very fast strain rates. Due to the low density of the aerogel sheets, however, electromechanical coupling and work output are low in the direction of large strain actuation.
Field activated electroactive polymers typically have higher efficiency, faster response speed, and require higher driving voltages than the ionic types. Dielectric elastomers (DEs) exhibit ultra-high strains when an electric field as high as 400 V/pm is applied. Specifically, highly prestrained acrylic elastomers achieve reversible electromechanical strains greater than 100% in area expansion, as well as a calculated maximum elastic energy density approaching 3.4 J/g and actuation stresses near 8 MPa. The response speed is high, and varies from a few hertz for large strain actuation up to the kilohertz range when operated at small strains. Prestrained silicone elastomers can also generate large strain, although their energy density is generally smaller than for the acrylics. The actuation of the DEs is instantaneous, meaning that a high electric field should be maintained in order to sustain actuated deformation. Moreover, current leakage and electromechanical instability at high strains can severely reduce the operation lifetime of DE actuators.
Shape memory polymers (SMPs) utilize the transition between rubbery and glassy states to aid in the deformation of rigid polymers. An SMP cast into a permanent shape can be mechanically stretched into a temporary shape at temperatures above its glass transition temperature (T_g). The temporarily deformed shape is retained after the polymer is cooled to below T_g. Upon reheating to above its T_g, the polymer regains its permanent shape. While an SMP may be used for multiple deployments, the requirement for mechanical stretching (programming) in each cycle causes complications in designing actuators for repeated deformation cycles. Furthermore, it is difficult to obtain intermediate shapes.
Bistable electroactive polymers (BSEP), (e.g. poly(tert-butylacrylate) (PTBA)) possess many of the same properties of typical synthetic thermoplastic polymers, but with the added electro-mechanical functionality that is unique to this material. The actuation of an exemplary sheet of PTBA is illustrated in FIG. 5A through FIG. 5B. The polymer has a T_gof 50° C.
FIG. 5A shows a schematic diagram of the actuation of a bistable electroactive polymer (BSEP) through several intermediate stages. At ambient temperature, polymer 34 a is a rigid plastic with an elastic modulus around 1 GPa, like polystyrene or poly(methyl methacrylate) that are used widely in many household applications. Above the T_g, polymer 34 b is softened to behave like a rubber. A voltage applied across the heated polymer film 34 b, via a pair of compliant electrodes 32 coated on opposite surfaces of the film, causes the rubbery polymer 34 c to expand in area and shrink in thickness. The film 34 d returns to its original shape when the voltage is removed. This electrical-to-mechanical transduction is of Maxwell nature. The actuation pressure is determined, similar to the DE actuators, by:
p=ε _rε₀ E ²=ε_rε₀(V/z)² Eq. 1
where E is the applied electric field, ε_ris the dielectric constant of the elastomer, ε₀is the permittivity of free space, V is the applied voltage, and z is the polymer film thickness. For small strains, the strain in the thickness direction (S_z) and area change (S_A) are:
S _Z=−ε₀ε_r E ² /Y S _A =−S _Z/(1+S _Z) Eq. 2
where Y is the elastic modulus of the rubbery polymer. The actuated state, 34 d in FIG. 5A is made stable by cooling the polymer below its T_gto lock in the deformation. The shape D is maintained at ambient temperature without any voltage applied. When heated to above its T_g, the deformed polymer returns to its original shape A. The performance of the BSEP actuator is determined by several key parameters including this shape memory property, dielectric breakdown strength, and the mechanical fatigue strength of the BSEP.
Using a diaphragm actuator configuration as shown in FIG. 5B the area strain increases with applied voltage according to Eq. 2. The maximum strain obtained is 335% in area, shown in FIG. 5C, and the calculated maximum stress is 3.2 MPa. The actuated deformation is reversible to its original stat (FIG. 5D), and it can be repeated for numerous cycles.
BSEP smart materials leverage the large-strain reversible actuation of DE polymers with the bistable deformation of SMPs, with low projected production cost, as the BSEP material can be produced like a commodity plastic, and structures and parts incorporating BSEP can be processed like typical thermoplastics. The BSEP materials are also nontoxic and recyclable.
Referring to FIGS. 6A and 6B one configuration of a tubular BSEP actuator 70 is fabricated as a long rectangular BSEP film 72. BSEP film 72 is shown in a pre-formed, flat configuration in FIG. 6A, and a rolled, tubular configuration in FIG. 6B. As seen in FIG. 6A, the BSEP film 72 is coated with a number of parallel patterned compliant electrodes 74 and conductive lines 78. A semi-rigid stripe 76 is attached to the top and bottom rims of the BSEP film 76.
Referring to FIG. 6B, the film 72 is rolled into a tubular shape forming aperture 36. In the configuration of FIG. 6B, the electrode areas 74 stack into 4 circumferential areas. However, it is appreciated that the electrodes may be sized to stack into any number of segments.
The BSEP film 72 is ideally pre-stretched before rolling. In the resulting tube 70 shown in FIG. 6B, the BSEP film 72 contracts to attain a 3-dimensional minimal energy structure. Hence, the tube wall buckles inward to close the aperture 36 of the tube 30 (see FIG. 3D). The circumferentially stacked electrode areas 74 can be independently actuated to cause the tube to open up and bend in different directions. The inside diameter and the air jetting angle of the tube aperture 36 can both be controlled by the driving voltage as indicated in Eq. 2.
The energy consumption in actuating the BSEP actuators 30 involves (1) heating the BSEP polymer 34 above T_gand (2) deforming the heated polymer 34 via DE actuation. The former process also incurs energy loss in heat dissipation, while the latter could lose energy due to incomplete electrical-to-mechanical conversion and current leakage.
For a rough estimation of energy needs in the electroactive register 14 design detailed above, we assume that the heat capacity of the BSEP polymer is comparable to amorphous polystyrene, or C_p˜1.22 J/g° C. The total amount of BSEP material used in an exemplary electroactive register 14 was found to be 10 grams. In a typical actuation operation, 50% of the BSEP polymers 34 are heated. The energy consumption for heating from 10° C. to 55° C., the low and high end of the temperature range in air-conditioner vent duct, respectively, is:
(10 g)×(50%)×(1.22 J/g° C.)×(55° C.−10° C.)=275 J Eq. 3
There is a heat loss through radiation and conduction. The conventional assumption is that this loss is about 50%. The energy for heating is:
275 J/50%=550 J Eq. 4.
For the DE actuation, the mechanical energy generated in each operation is limited to 0.5 J per gram of active material. Considering a 33% electrical-to-mechanical energy conversion efficiency, the total electricity consumed for DE actuation is:
(0.5 J/g)×(10 g)×(50%)/(33%)=7.6 J Eq. 5.
Hence, the total energy consumption in each actuation cycle is:
275 J+7.6 J=283 J Eq. 6.
During a normal daily activity, the electroactive register system is triggered on average 20 times, which means the total energy need is 5.66 kJ. This does not include the energy consumption for the embedded sensors 50 and control board 40 which is considered insignificant compared to the energy usage for the actuation.

Experimental Results

To validate the feasibility and impact of the electroactive register 14, a number of detailed 3D (three-dimensional) thermal simulations were performed using the Ansys Fluent Airpak tool, considering one occupant 18 (standing and sitting) and using specifications given in the FOA, Table 3. It was assumed that a room had a floor area of 6.1 m×7.6 m, and was 2.5 m tall. The wall heat transfer rate is 1.5 W/K/m², environment temperature is 95° F. and 42.8° F. for cooling and heating, respectively.
Results are shown in FIG. 7 and Table 3. In Table 3, the first 5 rows of values summarizes the characteristics of airflow for cooling or heating. The test was based on an air curtain airflow F_HSusing 8 tubes 30 a at the edge of the register 14, and the center airflow F_LSusing 10 centrally located tubes 30 b. One can see from the lower 6 rows in Table 3 that the temperature for the occupant 18 is between desired 74.6° F. and 70.1° F. As predicted, the temperature at head is cooler than that at feet for cooling. The temperature at head was desirably found to be higher than that at feet, but the difference meets the requirement of ANSI/ASHRAE Building Energy Standard. The wind velocity at head was 0.19-0.45 m/s, and mean age of air around the occupant was 320 seconds to 350 seconds. The predicted percentage of dissatisfied is 5.4-8.1%. Again, all satisfy the aforementioned Standard.
Most importantly, the predicted set point expansion, which is the horizontal temperature of same height averaged over a grid of 0.25 m between inside and outside of the air curtain F_HS, was found to be 5.4° F. for cooling, and 6.0 to 7.4° F. for heating.
FIG. 7 shows the airflow temperature distribution for heating a standing occupant with the simulated electroactive register 14. One can tell that the air curtain F_HSis not vertical to the floor, but rather conical.
For similar cooling effect, cooling the sitting occupant in Table 3 uses less cool air volume compared to cooling the standing occupant (0.236 vs 0.170 in total). Most likely, the airflow used to cool the standing occupant is far away from being optimal. As previously explained air tube 30 placement, sizing and shape may be varied to optimizing the airflow for the electroactive register 14.
According to the FOA, the COP (coefficient of performance) in this case is the ratio between energy (E_o) delivered to the occupant and the well plug energy (E_p) consumed by electroactive register. FOA assumes that E_o=23 W for cooling and E_o=18 W for heating, which are estimated minimum energy needed to cool or heat the occupant when the environment temperature is at set points of 79° F. and 66° F., respectively.
It would be fair only when the electroactive register 14 uses E_pwith the room temperature outside the air curtain at the set points. Such E_pcan be estimated as the energy difference (1) baseline case: a conventional HVAC to cool or heat the room without the occupant almost uniformly to the set points; and (2) an electroactive register to cool or heat the same room and the occupant under the set points for HVAC.
In Table 4, the COP is calculated for cooling a sitting occupant and heating a standing occupant from Table 3 as the airflow may be more optimized for the two. We calculate energy as the product of COP of HVAC, total air volume, volumetric heat capacity of air at room temperature, and temperature difference at HVAC register and air return vent.
It is interesting to see in Table 4 that electroactive register 14 dissipates less power than the two baseline cases. If we use the COP definition from the FOA, we get a negative COP, meaning that electroactive register 14 at localized thermal management (LTM) gains energy. This virtual energy gain is due to the fact that electroactive register 14 only cools and heats around the occupant 18, with limited heat exchange between the inside and outside of the air curtain.
To avoid confusion, COP is re-defined as energy for the baseline divided by energy used by electroactive register 14 in this proposal. Note that power to operate the smart register 14 is negligible compared to HVAC power, and it is ignored in calculating COP. As it is small, it is sufficient to use built-in energy harvesting.
The technology of the present description may be implemented as a series of electroactive register 14 products, an in particular stand-alone smart air conditioner registers, as well as the auxiliary mobile phone application software for indoor positioning of the occupant and communication with the smart registers 14, along with embedded software 46 and hardware 40 for real-time control and configuration of the smart registers 14.
The electroactive register 14 may be configured t for retro-fitting existing HVAC systems. As such, conventional registers or diffusers may be replaced by the smart registers 14 in a “plug and play” fashion. No professional installer is needed. In larger-scale applications, the electroactive register 14 may be installed in a building as am HVAC system 10 with optimal system configuration (e.g. duct 12 sizing and placement) for significant reduction in system size, construction cost further improvement in energy efficiency.
In some embodiments an occupant may install the electroactive register control apps in connected devices 58 such as smart phones, tablets, or computers without extra expense, for convenience in control but without adding any hardware cost.
The more customized the electroactive register 14 is for a specific building, the higher the energy efficiency. Therefore, flexible manufacturing methods may be applied to fabricate the electroactive register 14 by leveraging 3D printer technology. A set of software tools may be developed to accept building and thermal need specifications, and output optimized electroactive register design.
Embodiments of the present technology may be described with reference methods and systems according to embodiments of the technology, and/or algorithms, formulae, or other computational depictions, including flowchart illustrations, of which may also be implemented as computer program products. In this regard, each block or step of a flowchart, and combinations of blocks (and/or steps) in a flowchart, algorithm, formula, or computational depiction can be implemented by various means, such as hardware, firmware, and/or software including one or more computer program instructions embodied in computer-readable program code logic. As will be appreciated, any such computer program instructions may be loaded onto a computer, including without limitation a general purpose computer or special purpose computer, or other programmable processing apparatus to produce a machine, such that the computer program instructions which execute on the computer or other programmable processing apparatus create means for implementing the functions specified in the block(s) of the flowchart(s).
Accordingly, blocks of the flowcharts, algorithms, formulae, or computational depictions support combinations of means for performing the specified functions, combinations of steps for performing the specified functions, and computer program instructions, such as embodied in computer-readable program code logic means, for performing the specified functions. It will also be understood that each block of the flowchart illustrations, algorithms, formulae, or computational depictions and combinations thereof described herein, can be implemented by special purpose hardware-based computer systems which perform the specified functions or steps, or combinations of special purpose hardware and computer-readable program code logic means.
Furthermore, these computer program instructions, such as embodied in computer-readable program code logic, may also be stored in a computer-readable memory that can direct a computer or other programmable processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the block(s) of the flowchart(s). The computer program instructions may also be loaded onto a computer or other programmable processing apparatus to cause a series of operational steps to be performed on the computer or other programmable processing apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable processing apparatus provide steps for implementing the functions specified in the block(s) of the flowchart(s), algorithm(s), formula(e), or computational depiction(s).
It will further be appreciated that the terms “programming” or “program executable” as used herein refer to one or more instructions that can be executed by a processor to perform a function as described herein. The instructions can be embodied in software, in firmware, or in a combination of software and firmware. The instructions can be stored local to the device in non-transitory media, or can be stored remotely such as on a server, or all or a portion of the instructions can be stored locally and remotely. Instructions stored remotely can be downloaded (pushed) to the device by user initiation, or automatically based on one or more factors. It will further be appreciated that as used herein, that the terms processor, computer processor, central processing unit (CPU), and computer are used synonymously to denote a device capable of executing the instructions and communicating with input/output interfaces and/or peripheral devices.
1. An electroactive airflow distribution apparatus for HVAC, comprising: a housing; said housing being in fluid communication with an HVAC duct; plurality of electrically actuated tubes disposed in said housing; said tubes having an aperture configured for receiving airflow from the duct and directing said airflow outward toward an external location with respect to the duct; and said electrically actuated tubes being responsive to an electric signal such that the electrically actuated tubes change shape to modify the outward airflow delivered to the location.
2. The apparatus of any preceding embodiment, wherein the electrically actuated tubes are configured to constrict or expand to vary a speed of the airflow exiting the aperture of the tubes.
3. The apparatus of any preceding embodiment, wherein the electrically actuated tubes are configured to bend to vary a direction of the airflow exiting the aperture of the tubes.
4. The apparatus of any preceding embodiment: wherein the plurality of electrically actuated tubes comprises an outer array of electrically actuated tubes and an inner array of electrically actuated tubes; wherein the speed of the airflow exiting the outer array of electrically actuated tubes is much faster than the speed of the airflow an inner array of electrically actuated tubes so as to generate an air curtain surrounding said external location; wherein the air curtain generates limiting air exchange between said external location and a location outside said air curtain.
5. The apparatus of any preceding embodiment, wherein the air curtain generates a temperature gradient between said external location and a location outside said air curtain.
6. The apparatus of any preceding embodiment, further comprising: a controller coupled to each of the electrically actuated tubes; and wherein the controller is configured to individually actuate the electrically actuated tubes to change a direction of the airflow exiting the aperture of the tubes and thereby move the air curtain from said first external location to said second external location.
7. The apparatus of any preceding embodiment: wherein the controller is configured to receive data relating to a position of an occupant at said first external location; and wherein the controller is configured to individually actuate the electrically actuated tubes to move the air curtain in real time to thereby follow the occupant from said first external location to said second external location in response to receiving said position data.
8. The apparatus of any preceding embodiment, wherein the electrically actuated tubes comprise a smart material capable of electrically induced large-strain deformation to accommodate one or more of said bending, constriction or expansion.
9. The apparatus of any preceding embodiment, wherein said smart material comprises an electroactive polymer, said electroactive polymer being disposed between two conforming electrodes.
10. The apparatus of any preceding embodiment, wherein said electroactive polymer comprises a bistable electroactive polymer (BSEP).
11. An electroactive register for HVAC airflow distribution, comprising: a housing; said housing being in fluid communication with an HVAC duct; plurality of electrically actuated tubes disposed in said housing; said tubes having an aperture configured for receiving airflow from the duct and directing said airflow outward toward an external location with respect to the duct; wherein the plurality of electrically actuated tubes comprises an outer array of electrically actuated tubes and an inner array of electrically actuated tubes; wherein the speed of the airflow exiting the outer array of electrically actuated tubes is much faster than the speed of the airflow an inner array of electrically actuated tubes so as to generate an air curtain surrounding said external location; wherein the air curtain generates limiting air exchange between said external location and a location outside said air curtain.
12. The register of any preceding embodiment, wherein said electrically actuated tubes are responsive to an electric signal such that the electrically actuated tubes change shape to modify the outward airflow delivered to the location.
13. The register of any preceding embodiment, wherein the electrically actuated tubes are configured to constrict or expand to vary a speed of the airflow exiting the aperture of the tubes.
14. The register of any preceding embodiment, wherein the electrically actuated tubes are configured to bend to vary a direction of the airflow exiting the aperture of the tubes.
15. The register of any preceding embodiment, wherein the air curtain generates a temperature gradient between said external location and a location outside said air curtain.
16. The register of any preceding embodiment, further comprising: a controller coupled to each of the electrically actuated tubes; and wherein the controller is configured to individually actuate the electrically actuated tubes to change a direction of the airflow exiting the aperture of the tubes and thereby move the air curtain from said first external location to said second external location.
17. The register of any preceding embodiment: wherein the controller is configured to receive data relating to a position of an occupant at said first external location; and wherein the controller is configured to individually actuate the electrically actuated tubes to move the air curtain in real time to thereby follow the occupant from said first external location to said second external location in response to receiving said position data.
18. The register of any preceding embodiment, wherein the electrically actuated tubes comprise a smart material capable of electrically induced large-strain deformation to accommodate one or more of said bending, constriction or expansion.
19. The register of any preceding embodiment, wherein said smart material comprises an electroactive polymer, said electroactive polymer being disposed between two conforming electrodes.
20. The register of any preceding embodiment, wherein said electroactive polymer comprises a bistable electroactive polymer (BSEP).
21. A method for electroactive airflow distribution for HVAC, comprising: coupling a housing to be in fluid communication with an HVAC duct; wherein the housing comprises a plurality of electrically actuatable tubes each having an aperture; receiving airflow from the duct within an aperture of the electrically actuatable tubes and directing said airflow outward toward an external location with respect to the duct; and delivering an electric signal to said electrically actuatable tubes to change shape of said electrically actuatable tubes; and modifying the outward airflow delivered to the location as a result of changing the shape of said electrically actuatable tubes.
22. The method of any preceding embodiment, wherein changing the shape of said electrically actuatable tubes comprises constricting or expanding the tubes to vary a speed of the airflow exiting the aperture of the tubes.
23. The method of any preceding embodiment, wherein changing the shape of said electrically actuatable tubes comprises bending the tubes to vary a direction of the airflow exiting the aperture of the tubes.
24. The method of any preceding embodiment: wherein the plurality of electrically actuatable tubes comprises an outer array of electrically actuated tubes and an inner array of electrically actuatable tubes; wherein the speed of the airflow exiting the outer array of electrically actuated tubes is much faster than the speed of the airflow an inner array of electrically actuatable tubes so as to generate an air curtain surrounding said external location; wherein the air curtain generates limiting air exchange between said external location and a location outside said air curtain.
25. The method of any preceding embodiment wherein the air curtain generates a temperature gradient between said external location and a location outside said air curtain.
26. The method of any preceding embodiment, further comprising: individually actuating the electrically actuatable tubes to change a direction of the airflow exiting the aperture of the tubes; and moving the air curtain from said first external location to said second external location.
27. The method of any preceding embodiment, further comprising: receiving data relating to a position of an occupant at said first external location; and individually actuating the electrically actuatable tubes to move the air curtain in real time to thereby follow the occupant from said first external location to said second external location in response to receiving said position data.
28. The method of any preceding embodiment, wherein the electrically actuatable tubes comprise a smart material capable of electrically induced large-strain deformation to accommodate one or more of said bending, constriction or expansion.
29. The method of any preceding embodiment, wherein said smart material comprises an electroactive polymer, said electroactive polymer being disposed between two conforming electrodes.
30. The method of any preceding embodiment, wherein said electroactive polymer comprises a bistable electroactive polymer (BSEP). From the description herein, it will be appreciated that that the present disclosure encompasses multiple embodiments which include, but are not limited to, the following:
Although the description herein contains many details, these should not be construed as limiting the scope of the disclosure but as merely providing illustrations of some of the presently preferred embodiments. Therefore, it will be appreciated that the scope of the disclosure fully encompasses other embodiments which may become obvious to those skilled in the art.
In the claims, 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.” All structural, chemical, and functional equivalents to the elements of the disclosed embodiments that are known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the present claims. Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. No claim element herein is to be construed as a “means plus function” element unless the element is expressly recited using the phrase “means for”. No claim element herein is to be construed as a “step plus function” element unless the element is expressly recited using the phrase “step for”.

TABLE 1

Register Configurations to Modulate Velocity and Temperature

Description	Velocity modulation	Temperature Modulation

Air volume	0.252	m³/s	0.252	m³/s	0.252	m³/s	0.252	m³/s
in duct
Air velocity	1	m/s	6.5	m/s	4	m/s	4	m/s
in duct

# of edge	8	8	8	32
tubes
(air curtain)
# of center	20	20	20	9
tubes
Diameter for	12.0 cm/	12 cm/	11.44 cm/	5.64 cm/
edge tube	9.6 cm	9.2 cm	9.2 cm	2.58 cm
(inlet/outlet)
Diameter for	4 cm/	4 cm/	3.6 cm/	6 cm/
center tube	7.66 cm	7.62 cm	7.66 cm	11.4 cm
(inlet/outlet)

Air curtain	3.51	m/s	4	m/s	3.7	m/s	3.3	m/s
velocity
Center air	0.71	m/s	0.43	m/s	0.60	m/s	0.69	m/s
velocity
Air temperature	68.0°	F.	68.0°	F.	68.0°	F.	82.4°	F.
in duct
Air curtain	68.0°	F.	68.0°	F.	68.0°	F.	84.9°	F.
temperature
Center air	68.0°	F.	68.5°	F.	69.3°	F.	83.0°	F.
temperature

TABLE 2

Comparison of Materials Technologies

			Specific
			Elastic	Elastic
	Maximum	Maximum	Energy	Energy	Maximum	Relative
	Strain	Pressure	Density	Density	Efficiency	Speed
Type (Specific)	(%)	(MPa)	(J/g)	(J/cm³)	(%)	(full cycle)

Dielectric Elastomer	380	7.2	3.4	3.4	60-80	Medium
(Prestrained acrylic)
Dielectric Elastomer	63	3	0.75	0.75	90	Fast
(Prestrained silicone)
Bistable Electroactive	335	3.2	1.2	—		Medium
Polymer (PTBA)

Electrostrictive

4.3

43

0.49

0.92

~80

est.

Fast

polymer
(P(VDF-TrFE))
Electrostatic devices	50	0.03	0.0015	0.0025	>90	Fast
(Integ. force array)
Electromagnetic	50	0.1	0.003	0.025	>90	Fast
(Voice Coil)
Piezoelectric Ceramic	0.2	110	0.013	0.1	>90	Fast
(PZT)
Piezoelectric Single	1.7	131	0.13	1	>90	Fast
Crystal (PZT-PT)
Piezoelectric Polymer	0.1	4.8	0.0013	0.0024	—	Fast
(PVDF)
Shape memory alloy	>5	>200	>15	>100	<10	Slow
(TiNi)
Shape memory	100	4	2	2	<10	Slow
polymer
(Polyurethane)
Thermal (Expansion -	1	78	0.15	0.4	<10	Slow
Al dT = 500K)

Conducting Polymer

10

450

23

<5

est

Slow

(PANI)
Ionic gels	>40	0.3	0.06	0.06	30	Slow
(Polyelectrolyte)
IPMC	>3	30	0.0037	0.0055	2.9	Slow
Carbon nanotubes	<2	27		0.04	>1	Fast
Carbon nanotube	200*	3.2**	0.03**			Fast
aerogels
Magnetostrictive	0.2	70	0.0027	0.025	60	Fast
(Terfenol-D)

*In width direction, strain is 3% in length direction
**In length direction

TABLE 3

Electroactive Register to Cool/Heat Standing/Sitting Occupant

Description	Cool Stand	Cool Sit	Heat Stand	Heat Sit

Air curtain	0.190	m³/s	0.110	m³/s	0.169	m³/s	0.254	m³/s
volume
Air curtain	3.6	m/s	3.8	m/s	5.5	m/s	5.0	m/s
velocity
Center air	0.046	m³/s	0.060	m³/s	0.057	m³/s	0.054	m³/s
volume
Center air	0.65	m/s	0.65	m/s	0.8	m/s	1.2	m/s
velocity
Temperature	68°	F.	68°	F.	82.4°	F.	82.4°	F.
at register
Temperature	73.7°	F.	73.2°	F.	74.8°	F.	73.3°	F.
at head
Temperature	74.4°	F.	74.6°	F.	71.6°	F.	70.1°	F.
at feet
Wind speed	0.21	m/s	0.25	m/s	0.19	m/s	0.45	m/s
at head
Mean age of	340	s	320	s	350	s	357	s
air inside
air curtain

Predicted	5.4%	7.8%	6.8%	8.1%
percentage of
dissatisfied

Predicted	5.4°	F.	5.4°	F.	7.4°	F.	6.0°	F.
setpoint
expansion

TABLE 4

COP of Electroactive Register

	Electroactive		Electroactive
	Register Cool	Cool to	Register Feat	Heat to
Description	to 74.9° F.	79.1° F.	to 74.7° F.	66° F.

COP of	4.5 (does not affect COP)
HVAC
Heat	0.00121 J/cm³/K, or 2178 J/m³/F. (does not affect COP)
capacity
of air

Airflow	0.170	m³/s	0.225	m³/s	0.226	m³/s	0.214	m³/s
volume
Temperature	68.0°	F.	68.0°	F.	85.0°	F.	86.0°	F.
at register
Temperature	80.7°	F.	79.3°	F.	68.2°	F.	65.3°	F.
at return
vent
Energy used	1045	W	1231	W	1838	W	2144	W

COP	1.18	—	1.17	—

Claims

What is claimed is:

1. An electroactive airflow distribution apparatus for HVAC, comprising:

a housing;

said housing being in fluid communication with an HVAC duct;

plurality of electrically actuated tubes disposed in said housing;

said tubes having an aperture configured for receiving airflow from the duct and directing said airflow outward toward an external location with respect to the duct; and

said electrically actuated tubes being responsive to an electric signal such that the electrically actuated tubes change shape to modify the outward airflow delivered to the location.

2. An apparatus as recited in claim 1, wherein the electrically actuated tubes are configured to constrict or expand to vary a speed of the airflow exiting the aperture of the tubes.

3. An apparatus as recited in claim 2, wherein the electrically actuated tubes are configured to bend to vary a direction of the airflow exiting the aperture of the tubes.

4. An apparatus as recited in claim 2:

wherein the plurality of electrically actuated tubes comprises an outer array of electrically actuated tubes and an inner array of electrically actuated tubes;

wherein the speed of the airflow exiting the outer array of electrically actuated tubes is much faster than the speed of the airflow an inner array of electrically actuated tubes so as to generate an air curtain surrounding said external location;

wherein the air curtain generates limiting air exchange between said external location and a location outside said air curtain.

5. An apparatus as recited in claim 4, wherein the air curtain generates a temperature gradient between said external location and a location outside said air curtain.

6. An apparatus as recited in claim 4, further comprising:

a controller coupled to each of the electrically actuated tubes; and

wherein the controller is configured to individually actuate the electrically actuated tubes to change a direction of the airflow exiting the aperture of the tubes and thereby move the air curtain from said first external location to said second external location.

7. An apparatus as recited in claim 6:

wherein the controller is configured to receive data relating to a position of an occupant at said first external location; and

wherein the controller is configured to individually actuate the electrically actuated tubes to move the air curtain in real time to thereby follow the occupant from said first external location to said second external location in response to receiving said position data.

8. An apparatus as recited in claim 3, wherein the electrically actuated tubes comprise a smart material capable of electrically induced large-strain deformation to accommodate one or more of said bending, constriction or expansion.

9. An apparatus as recited in claim 8, wherein said smart material comprises an electroactive polymer, said electroactive polymer being disposed between two conforming electrodes.

10. An apparatus as recited in claim 9, wherein said electroactive polymer comprises a bistable electroactive polymer (BSEP).

11. An electroactive register for HVAC airflow distribution, comprising:

a housing;

said housing being in fluid communication with an HVAC duct;

plurality of electrically actuated tubes disposed in said housing;

said tubes having an aperture configured for receiving airflow from the duct and directing said airflow outward toward an external location with respect to the duct;

12. A register as recited in claim 11, wherein said electrically actuated tubes are responsive to an electric signal such that the electrically actuated tubes change shape to modify the outward airflow delivered to the location.

13. A register as recited in claim 12, wherein the electrically actuated tubes are configured to constrict or expand to vary a speed of the airflow exiting the aperture of the tubes.

14. A register as recited in claim 13, wherein the electrically actuated tubes are configured to bend to vary a direction of the airflow exiting the aperture of the tubes.

15. A register as recited in claim 11, wherein the air curtain generates a temperature gradient between said external location and a location outside said air curtain.

16. A register as recited in claim 11, further comprising:

a controller coupled to each of the electrically actuated tubes; and

17. A register as recited in claim 16:

18. A register as recited in claim 14, wherein the electrically actuated tubes comprise a smart material capable of electrically induced large-strain deformation to accommodate one or more of said bending, constriction or expansion.

19. A register as recited in claim 18, wherein said smart material comprises an electroactive polymer, said electroactive polymer being disposed between two conforming electrodes.

20. A register as recited in claim 19, wherein said electroactive polymer comprises a bistable electroactive polymer (BSEP).

21. A method for electroactive airflow distribution for HVAC, comprising:

coupling a housing to be in fluid communication with an HVAC duct;

wherein the housing comprises a plurality of electrically actuatable tubes each having an aperture;

receiving airflow from the duct within an aperture of the electrically actuatable tubes and directing said airflow outward toward an external location with respect to the duct; and

delivering an electric signal to said electrically actuatable tubes to change shape of said electrically actuatable tubes; and

modifying the outward airflow delivered to the location as a result of changing the shape of said electrically actuatable tubes.

22. A method as recited in claim 21, wherein changing the shape of said electrically actuatable tubes comprises constricting or expanding the tubes to vary a speed of the airflow exiting the aperture of the tubes.

23. A method as recited in claim 22, wherein changing the shape of said electrically actuatable tubes comprises bending the tubes to vary a direction of the airflow exiting the aperture of the tubes.

24. A method as recited in claim 22:

wherein the plurality of electrically actuatable tubes comprises an outer array of electrically actuated tubes and an inner array of electrically actuatable tubes;

wherein the speed of the airflow exiting the outer array of electrically actuated tubes is much faster than the speed of the airflow an inner array of electrically actuatable tubes so as to generate an air curtain surrounding said external location;

25. A method as recited in claim 24, wherein the air curtain generates a temperature gradient between said external location and a location outside said air curtain.

26. A method as recited in claim 24, further comprising:

individually actuating the electrically actuatable tubes to change a direction of the airflow exiting the aperture of the tubes; and

moving the air curtain from said first external location to said second external location.

27. A method as recited in claim 26, further comprising:

receiving data relating to a position of an occupant at said first external location; and

individually actuating the electrically actuatable tubes to move the air curtain in real time to thereby follow the occupant from said first external location to said second external location in response to receiving said position data.

28. A method as recited in claim 23, wherein the electrically actuatable tubes comprise a smart material capable of electrically induced large-strain deformation to accommodate one or more of said bending, constriction or expansion.

29. A method as recited in claim 28, wherein said smart material comprises an electroactive polymer, said electroactive polymer being disposed between two conforming electrodes.

30. A method as recited in claim 29, wherein said electroactive polymer comprises a bistable electroactive polymer (BSEP).