US20110253350A1

US20110253350A1 - Method and apparatus for enhancing convection through heat exchangers

Info

Publication number: US20110253350A1
Application number: US13/090,811
Authority: US
Inventors: Paul Belles
Original assignee: Individual
Current assignee: Individual
Priority date: 2010-04-20
Filing date: 2011-04-20
Publication date: 2011-10-20

Abstract

In an apparatus for enhancing convection of air at a working element of a heat exchanger, a main flow of air is directed toward the working element. A priming flow of pressurized air is provided to impinge upon the working element, to disrupt a stagnant boundary layer adjacent the working element, and to thereby enhance the main flow of air.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a non-provisional of, claims the benefit of, and hereby incorporates herein in its entirety, U.S. Pat. App. No. 61/326,078, filed Apr. 20, 2010.

FIELD OF THE INVENTION

The present invention generally relates to convection heating and/or cooling systems and, more specifically, to enhancing convection at a working element of a heat exchanger.

BACKGROUND OF THE INVENTION

Baseboard heating and/or cooling units (hereinafter “baseboard units”) are commonly used as components of heating and/or cooling systems, particularly for residential household applications. Baseboard units typically have low, wide shapes. Referring to FIGS. 1-2 an exemplary conventional baseboard unit 2 is shown installed to a wall 4 near a floor 6, as known in the art. The installation location enhances natural convective flow from the floor 6 upward through the baseboard unit 2 and along the wall 4, as further discussed below.
The exemplary baseboard unit 2 includes a housing 12 that is fitted to run along the base of the wall 4. As shown, the conventional housing 12 is substantially rectangular and has side panels 14, a bottom surface 16, a rear surface 18, a top surface 20 and a front surface 22. The housing 12 may also include input ports 24 disposed in one or both of the side panels 14. The input ports 24 may include an electrical connection, a control signal input, and/or a supply and/or return connections for heating and/or cooling fluid (working fluid). Alternatively, working fluid may be supplied and returned through floor cuts made under the housing 12. Or the baseboard unit 2 may be electrically powered. The baseboard unit 2 typically is secured to the wall by fasteners 26, such as screws or the like, that are inserted through mounting holes defined in the rear surface 18 of the housing 12 and into a wall of the room.
As shown in FIGS. 1 and 2, the front surface 22 of the housing 12 defines an upper opening 28 and a lower opening 30 that, along with the inner cavity of the housing 12, form one or more connection passages. The upper opening 28 and the lower opening 30 operate interchangeably as an inlet vent and an outlet vent depending on the operating mode of the baseboard unit 2. The openings 28, 30 may be positioned within contours 32 formed in the front surface 22 to reduce the likelihood of foreign objects or particulate matter entering into the baseboard unit 2 without adversely impacting air flow through the baseboard unit 2.
A working element 34 is mounted in the housing 12, within and across the connecting passage(s) between the upper and lower openings 28, 30, on a supporting structure 36. The working element typically is a finned tube through which a working fluid flows. Alternatively, the working element 34 may include one or more resistive heaters that are supplied with electricity via the electrical connection of the input ports 24.
In a heating mode, for example, the working element 34 is maintained hotter than room temperature by electric current, or by an external working fluid source (not shown). The thermal difference causes heat transfer from the working element 34 to air in the housing 12. As the air is heated, its density decreases so that the heated air rises from the inlet opening 30 through the working element 34 and out the upper outlet opening 28, as indicated by the arrows in FIGS. 1-2. It will be appreciated that in a cooling-mode, the reverse process occurs. The above-described natural convective flow through the housing 12 is a well-known feature of conventional baseboard units, such as the exemplary unit 2.
When the working element 34 is operated at full capacity, with a large temperature differential between the ambient temperature of the room and element 34 (i.e., when the working element is maintained at about 160-220° F.), the baseboard unit 2 can operate effectively. For instance, air flows through the housing 12 and upward along the wall 4 at a sufficient flow rate to initiate a larger convection cycle throughout the room. As a result, the heat transfers evenly throughout the room and there is a small temperature gradient. Even heat transfer is generally desired because it produces a more comfortable environment. The required flow rate through the working element 34 varies based on the dimensions of the room and of the working element, according to equations and tables known to those of skill.
Yet, operating the element 34 at full capacity is often inefficient from an energy consumption perspective and may not be required for more than a few days of the year depending on regional weather patterns. In addition, it may take 30-minutes or longer for the element 34 to reach full capacity (i.e., thermal equilibrium with the working fluid and with the air flowing through the housing 12) and for the larger convection cycle to form.
Operation of the baseboard unit 2 is very inefficient as it is ramped up to full capacity. Further, when the temperature differential is relatively small (e.g., when the element 34 is set at low capacity, such as below 160° F.; or, when the working element 34 is disposed at the end of a series of similar working elements supplied with a working fluid that approaches room temperature as it flows through the elements), the convection cycle within the housing 12 has difficulty forming due to lesser density difference between the room air and the air within the housing. As a result, the desired larger convection cycle throughout the room is not formed such that, even if some air does flow through the housing 12 and upward along the wall 4, the rate of upward air flow is not sufficient to induce air turnover throughout the room. This results in uneven heat transfer (i.e., a large temperature gradient across the room) and a less comfortable environment.
These problems exist in both heating- and cooling-modes of operation, but are exacerbated in cooling-mode operation because cooling-mode operation often has greater difficulty forming a convection cycle through the housing 12 as the outlet air must flow across the floor 6, rather than up the wall 4. Across-the-floor flow often tends to produce thermal layering, rather than convective mixing.
Forced or artificial convection, generically, has been well known for enhancing heat transfer through a heat exchanger. However, forced convection has not been implemented in a baseboard unit at least in part because known designs impose an either-or trade off between natural convection and forced convection. Since baseboard units are designed and installed so as to render natural convection sufficient during steady state operation, it is neither efficient, economical, nor desirable to utilize forced convection in existing baseboard units.
Thus, there has been a long-standing need for a baseboard unit that is capable of operating more efficiently, responding more rapidly to changes in demand, at smaller temperature differentials, and, particularly, in a manner that improves cooling-mode operation, without detracting from the well-known benefits of natural convective flow.
Referring to FIG. 3, a control unit 38 is shown connected in communication with the element 34 for use with the baseboard unit 2. Known control units include bimetallic thermostats that are connected between a voltage supply 40 and ground. More complex control units may be connected in communication with one or more input/output devices.
The element 34 can be connected to an external heat and/or cold source 50, via a connection 51 that is controllable by the control unit 38. The external heat and/or cold source 50 can include a steam boiler, a geothermal heating and/or cooling system or any other source of heat and/or cold including an electrical power supply. The connection 51 can be any of a valve, a switch, a clutch, or any other automatically controllable device commonly used for selectively supplying fluid, electricity, or power to a powered apparatus.
The external heat and/or cold source 50 can be chosen based on energy prices, regional temperature patterns and other available resources. However, the external heat and/or cold source 50 may be inflexible or slow to respond to changing demands. For instance, a steam heat source works well for high temperature differential operation, but is a less effective option at low temperature differential ranges. To operate in a low temperature differential range, a steam-based element might operate at full-on then full-off intervals. This style of operation provides the desired room temperature when averaged over time, but is not necessarily comfortable or efficient.
In addition, existing or already-installed baseboard units may utilize an element 34 that does not effectively service the entire room of the household. For example, a household may only utilize a single type of baseboard unit that is a fixed five feet (5′) in length. Most rooms in the household may have walls with over ten feet (10′) of available space for heating units and, therefore, can be provided with two or more baseboard units. However, some rooms may be oddly configured, have a doorway break up the wall space or have a wall with under ten feet (10′) of available space for a heating unit and, therefore, be limited to only one baseboard unit that is, for instance, located in a remote corner of the room. As a result, the room may be underserved or unevenly served unless expense is incurred for upgrading, replacing or modifying the baseboard unit.
Thus, there is a long-standing need for a baseboard unit with an expanded functional range of the element 34, smooth average output of the element 34, and increased versatility and area of effect.
There is also a need for a wider range of baseboard unit designs that can be applied in a wider range of installations and applications.
There is also a need for an economical means of addressing the deficiencies of the conventional baseboard unit.
An object of the present invention is, therefore, to provide a baseboard unit that overcomes the above-mentioned deficiencies of prior baseboard units.

SUMMARY OF THE INVENTION

Accordingly, embodiments of the present invention provide a pilot or priming air flow across a working element of a heat exchanger, thereby disrupting a static boundary layer or aerodynamic surface film adjacent to the heat transfer surfaces of the working element. Disruption of the boundary layer enhances conductive heat transfer from the working element to adjacent air, while also introducing turbulent flow within the adjacent air. In some embodiments of the invention, diminished flow resistance in the turbulent flow regime enhances the rate of natural convective flow driven by air density differences within the baseboard unit housing. In other embodiments, diminished flow resistance enhances forced convection flow driven by a main fan. Accordingly, provision of a pilot air flow, according to an embodiment of the present invention, enhances convective heat transfer between the working element and a main flow of air.
In some embodiments of the present invention, an apparatus for enhancing convection of air through a heat exchanger includes a first means for producing, within a housing of the heat exchanger, a priming flow of pressurized air that impinges upon a working element of the heat exchanger to disrupt a stagnant boundary layer adjacent the working element. Such an apparatus also includes a second means for providing, into the housing, a main flow of air directed toward the working element.
In some embodiments of the present invention, an apparatus is provided for enhancing natural convection of ambient air at a working element of a heat exchanger. Such an apparatus includes a substantially closed and elongated plenum extending generally parallel to and proximate the working element. The plenum of the apparatus is filled with pressurized air and has at least one opening disposed such that a first quantity of the pressurized air exits the opening as a priming air flow, which induces a second quantity of ambient air to flow as a main air flow onto and across a surface of the working element.
In an aspect of the present invention, convection of ambient air at working element of a heat exchanger is enhanced by supplying a pressurized priming air flow onto a the working element of the heat exchanger, substantially without obstructing access of ambient a main air flow to the working element; and by adjusting supply of the pressurized priming air flow to induce impingement of the ambient main air flow onto the working element.
In some embodiments of the present invention, one or more fans are provided for producing the pressurized priming air flow.
In select embodiments of the present invention, at least one of the fans is movably mounted to the heat exchanger and is automatically movable in response to a sensed parameter.
In some embodiments of the present invention, the plenum is provided as a tube, the at least one opening is provided as a slot in the wall of the tube, and a fan is mounted to an open end of the tube for filling the plenum with pressurized air,
In selected embodiments of the present invention, the plenum is disposed below and generally coextensive with the working element.
In some embodiments of the present invention, the plenum is formed by a generally cylindrical first semi-tube of a first diameter and by a generally cylindrical second semi-tube of a diameter smaller than the first diameter. Each of the first and second semi-tubes has a capped end and an open end. The capped ends of the first and second semi-tubes are fastened together. The second semi-tube is nested within and generally radially opposed to the first semi-tube, so that the at least one opening is formed between the two semi-tubes as at least two slots along the length of the generally cylindrical plenum.
In selected embodiments of the present invention, the first and second semi-tubes are additionally fastened together at intervals along the length of the plenum to form a plurality of slots along the length of the plenum.
In selected embodiments of the present invention, the capped ends of the first and second semi-tubes are pivotally fastened together.
In some embodiments of the present invention, the plenum is provided within a portion of a housing generally enclosing the working element. The portion of the housing enclosing the plenum is separated from the remainder of the housing by at least one gap. The gap provides access of ambient air to the working element. The at least one opening of the plenum is disposed adjacent to the at least one gap.
In selected embodiments of the present invention, a fan is mounted in a wall of the plenum facing outward from the working element for producing pressurized air in the plenum.
In other embodiments of the present invention, a baseboard unit is provided with one or more fans mounted along the length of the housing for enhancing natural convection through a heating ventilation and air conditioning unit.
In other embodiments of the present invention, a stacked baseboard system is provided that includes stacked, horizontally-oriented heating and cooling elements and fans for enhancing and/or redirecting natural convective flow within the system.
In select embodiments of the present invention, at least one fan is operatively connected to a fan control unit that regulates the fan in response to sensed parameters.
In select embodiments of the present invention, filters are mounted to the housing of the baseboard unit to reduce the likelihood that foreign objects and/or dirt are inserted or deposited in the housing.
Some embodiments of the present invention provide a fan control unit that monitors operation of the fans to detect when the filter, a specific fan or the heating and/or cooling unit needs to be serviced.
One aspect of the present invention is that, in some embodiments, a baseboard unit can be effectively operated even at smaller-than-conventional temperature differentials between the working element and the room air.
Another aspect of the present invention is that, in some embodiments, cooling-mode operation of a baseboard unit is enhanced.
Another aspect of the present invention is that, in some embodiments, a baseboard unit may be operated with smoothed average output.
Another aspect of the present invention is that, in some embodiments, enhancement of natural convective flow improves the energy efficiency of a baseboard unit.
Another aspect of the present invention is that, in some embodiments, enhancement of natural convective flow improves the response time of a baseboard unit.
Another aspect of the present invention is that, in some embodiments, natural convective flow through a baseboard unit is adjustable so as to increase the versatility and area of effect of a working element within the baseboard unit.
These and other features of the present invention are described with reference to drawings of preferred embodiments of a forced convection baseboard unit. The illustrated embodiments of a forced convection baseboard unit are intended to illustrate selected embodiments of the present invention, without thereby limiting the claims appended hereto.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a conventional baseboard unit.

FIG. 2 shows a cross section of the baseboard unit, along line 2-2 shown in FIG. 1.

FIG. 3 shows a wiring diagram of a control system usable with the baseboard unit shown in FIGS. 1 and 2.

FIGS. 4 and 5 show cross sections of forced convection baseboard units including fans, according to embodiments of the present invention.

FIG. 6 shows a daisy chain of four fans connected to a fan control unit via a common power and control supply according to an embodiment of the present invention.

FIG. 7 shows a wiring diagram of a fan control system according to an embodiment of the present invention.

FIGS. 8 and 9 show cross sections of forced convection baseboard units including filters according to embodiments of the present invention.

FIG. 10 shows another forced convection baseboard unit having a fan installed therein according to another embodiment of the present invention.

FIG. 11 shows another baseboard unit having a duct installed along a length of the baseboard unit and a fan positioned at one end of the duct according to an embodiment of the present invention.

FIG. 12 shows detail of FIG. 11.

FIG. 13 shows a baseboard unit having a fan installed therein and a solar panel connected to the fan according to an embodiment of the present invention.

FIG. 14 shows a heating ventilation and air condition unit having fans installed thereto according to an embodiment of the present invention.

FIG. 15 shows a stacked baseboard system having fans disposed therein according to an embodiment of the present invention.

FIG. 16 shows a slotted air tube installed with a working element of a baseboard unit, according to another embodiment of the present invention.

FIG. 17 shows a slitted air tube installed with a working element of a baseboard unit, according to another embodiment of the present invention.

FIGS. 18A-18B show a ducted cover with integral fan installed onto a baseboard unit, according to another embodiment of the present invention.

FIG. 19 shows staggered arrays of plural working elements and priming air plenums within a heat exchanger, according to another embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

As used in context of the embodiments described below, the terms “substantially” or “about” are meant to indicate a shape or condition within reasonably achievable manufacturing and assembly tolerances, relative to an ideal desired condition suitable for achieving the functional purpose of a component or assembly. The term “significant” is meant to indicate a shape, condition, feature, or quality that one of ordinary skill would appreciate as measurably affecting desired function or operation of the described embodiment. The term “generally” is meant to indicate a shape or condition inclusive of deviations consequent to normal manufacturing practice, and also includes intentional features that do not significantly deviate from the general shape or condition.
FIG. 4 shows in cross-section an improved baseboard unit 2 a, including a fan 52, in accordance with an embodiment of the present invention. Components generally similar to those of the conventional baseboard unit 2 (shown in FIGS. 1-3) are similarly numbered.
In the improved baseboard unit 2 a, one or more fans 52 are mounted to the housing 12 for entrainment of ambient air as further discussed below. In select embodiments, the fans 52 are small electric fans, such as the fans used in a computer or other electronic device for transferring heat away from the processor and/or motherboard. In other embodiments, the fans 52 may be centrifugal (squirrel cage) fans.
When activated, the fans 52 inject small quantities of air across the working element 34. The injected air has dynamic or Bernoulli pressure higher than that of the room air. When the injected air impinges on surfaces of the working element 34, an insulative boundary layer of stagnant air adjacent the working element surfaces becomes entrained with the injected air (similar to the Coanda effect). Air proximate but not adjacent to the working element also becomes entrained by the injected air, and is thus brought directly into contact with the surfaces of the working element. Therefore, the injected air induces air flow across the surfaces of the working element 34 by an amount significantly greater than the rated air flow of the fans 52. Entrainment by the injected air is particularly pronounced in embodiments where the fans 52 inject air through restricted passages, such as between fins of a finned-tube working element 34 (e.g., as shown in FIGS. 10-13). For example, entrained air flow across selected surfaces of the working element 34 may augment the rated flow of the fans 52 by a factor of between about 50% and about 500%, depending on configuration of the fans and of the working element.
In select embodiments, the priming flow may be enhanced by thermal effects, in particular, by an increase of the priming air temperature across the working element 34. This increase of temperature and consequent expansion may produce standing pressure waves across the working element, so that the priming flow can to some extent act as an acoustic pump driving the main flow through the heat exchanger.
As a result of the incorporation of the fans 52 to the baseboard unit 2 a, heat transfer from the element 34 can occur at significantly lower temperatures. For instance, without the fans 52, the element 34 would need to be heated to between 160-220° F. in order to generate a sufficient density difference so as to generate natural convection air flow adequate to provide the proper heating action. In contrast, by substantially lowering flow resistance across the working element 34, the fans 52 enable smaller-than-normal density differences, produced by the element 34 operating at lower-than-normal temperatures, to establish convection currents that move blankets of air around the room, such as across the floor or ceiling or up/down the wall. The blankets of air not only circulate around the room in convection currents, but the blankets of air also radiate heat (or absorb heat) throughout the room. Thus, with the fans 52, the element 34 only needs to be heated to around 120-140° F. Therefore, water flowing through the element 34 can be returned to the heat source 50 at a lower temperature, while still providing effective heating of a room. The lower return temperature enhances efficiency of heat transfer from the heat source 50 to the water.
In an embodiment of the invention as shown in FIG. 4, each of a plurality of fans 52 is mounted internally to a corresponding wall of a housing 12 in an improved baseboard unit 2 a. For instance, at a bottom surface 16 a first fan 52 a is mounted to provide a flow path that is oriented substantially rearwardly and at a slight upward angle, pointing to the bottom of the element 34. At the rear surface 18 a second fan 52 b is mounted to provide a flow path that is oriented substantially upwardly and parallel to the rear surface 18. At the top surface 20 a third fan 52 c is mounted to provide a flow path that is oriented substantially horizontally and frontwardly, pointing to the upper opening 28 of the front surface 22. At the front surface 22 a fourth fan 52 d is mounted to provide a flow path that is oriented substantially vertically and upwardly, parallel to the front surface 22. These various fans 52 can be controlled in gang, or individually, to achieve the desired air flow around the working element 34, as further discussed below with reference to FIG. 6. For example, the fourth fan 52 d can provide a “bypass” flow that diminishes heat transfer between the working element 34 and the room air flowing through the housing 12.
The fans 52 can be mounted to the walls of the housing 12 using known mounting means, including fasteners or screws, mounting brackets, adhesives, magnets and the like. Fasteners are ideal for simple installations, whereas mounting brackets are preferable for more complex installations. In particular, mounting brackets can be utilized to position the fans 52 in a variety of positions (i.e., away from the walls of the housing 12), orientations (i.e., angled relative to the adjacent wall of the housing 12, like the second fan 52 b and the fourth fan 52 d, as shown in FIG. 4) and directions (i.e., rearwardly, forwardly, upwardly and downwardly) depending on the size, shape and configuration of the housing 12. The fans 52 can be positioned, oriented and provided at greater or lesser frequency on any surface or adjoining portion of a surface without departing from the present invention. In addition, the fans 52 can be oriented to run along the length of the baseboard unit 2 a, perpendicularly to the normal air flow through the baseboard unit 2 (see FIG. 2). Such a lateral orientation of the fans 52 can be used to expand the lateral effect of the improved baseboard unit 2 a, for instance, to service a portion of the room that would not otherwise receive sufficient air flow.
In some embodiments, means for actuating one or more of the mounting brackets may be operably connected to a fan control unit as further discussed below with reference to FIG. 7. For example, acceptable actuating means may include a toothed rack driven by a pinion of a DC stepper motor, or a pneumatic piston actuator driven by actuation of air valves. Those of ordinary skill can realize other acceptable means for actuating a mounting bracket.
FIG. 5 shows in cross-section an improved baseboard unit 2 b according to another embodiment of the invention, in which one fan 52 e is mounted externally of the housing 12 in register with the lower opening 30. In heat-mode operation, the fan 52 e can direct air from the floor, into the housing 12, across the element 34 and upward out of the housing 12. In this arrangement, the fan 52 e supplements the natural convection cycle of the element 34 and is positioned upstream, in cooler air, which can be moved more efficiently.
In cold-mode operation, the fan 52 e can direct air in the same direction and, thus, reverse the convection cycle of the element 34. Or, alternatively, the fan 52 e can change direction (i.e., have its flow-direction reversed) to supplement the convection cycle of the element 34. The direction of the fan 52 e can be set based on monitored operational efficiencies.
It should be appreciated that the fan 52 e can alternatively be positioned in register with the upper opening 28, or fans 52 can be positioned at both of the openings 28, 30. Preferably, at least one fan 52 is positioned upstream in the dominant flow path in order to improve the efficiency of the fan 52 with respect to moving the air.
Referring to FIG. 6, the fans 52 are connected to a common power and control supply 54. As shown, the common power and control supply 54 is a bundle of electric wires having branches and/or connection points that are, optionally, disposed within a pipe 56. The pipe 56 can be made from a heat resistant and/or heat shielding material or can merely be provided to facilitate the installation of the fans 52 and the common power and control supply 54. Preferably, the pipe 56 is heat resistant polymeric tube having a slit formed axially along a length thereof for passing the electric wires.
The fans 52 can be connected in a daisy-chain manner to the common power and control supply 54. Four fans 52 are shown in FIG. 6. However, any number of fans 52 can be connected without affecting how the present invention operates. In the illustrated embodiment, each fan 52 includes an input port and an output port that are disposed along one side of the fan 52 for ease of access and interconnectivity using electrical wires 58. The electrical wires 58 between adjacent fans 52 are anchored to the housing 12 using clamps 60 or other anchoring devices to retain the electrical wires 58 away from the element 34. The daisy-chain connection electrically connects the fans 52 in parallel to one another so that if one fan 52 fails, the remaining fans 52 are unaffected. Via the common power and control supply 54, the fans 52 are connected to a fan control sub-unit 62 and, optionally, to additional elements, such as more fans, sensors or other peripheral devices.
Referring to FIG. 7, the fan control sub-unit 62 is shown interconnected with the control system 36. The fan control sub-unit 62, which is provided with an integral processor and memory, regulates the direction and rate of air flow produced by the fans 52, individually or in group based on, at least, the same conditions as the control unit 38. Since the fans 52 can be activated to produce a flow in any direction, the fan control sub-unit 62 can instruct the fans 52 to operate in conjunction with the convection cycle formed naturally by the element 34. Alternatively, the fan control sub-unit 62 can instruct the fans 52 to operate against the naturally forming convection cycle. For example, in select embodiments of the invention, the fan control sub-unit 62 can regulate the fans 52 during cooling-mode operation of a baseboard unit to create a counter-convection cycle (i.e., upward flow), thereby pumping cold air upward to more evenly distribute air throughout the room. As another example, in selected embodiments of the present invention, the fan control sub-unit 62 can be configured to operate the fans 52 when both a sensed room temperature and a sensed differential of room temperature from working element temperature drop below pre-determined threshold values. The threshold values can be determined, for example, based on comfort of room occupants and based on a measured or calculated minimum temperature difference required to initiate natural convection from the baseboard unit in the particular room.
The fan control sub-unit 62 shares the input and output devices of the control unit 38, such as the user interface 44, the temperature sensor 46 and the time sensor 48 through the control unit 38. The fan control sub-unit 62 can share the input and output devices of other equipment, such as an external thermometer. The fan control sub-unit 62 can also accept additional inputs, including flow feedback sensors 66 and energy sensors 68. The flow feedback sensors 66 are connected to the fans 52 and monitor feedback from the fans 52. The energy sensors 68 are connected between the power supply 40 and the element 34 and the fans 52 and monitor energy consumption of each of the element 34 and the fans 52, respectively.
By leveraging additional inputs, the fan control sub-unit 62 can further increase the energy efficiency and responsiveness of the improved baseboard units. For example, the fan control sub-unit 62 can implement an algorithm for regulating the fan(s) 52 according to inputs including the room temperature and the outdoor temperature.
The fan control sub-unit 62 can also include a learning module 70 for intelligently regulating the fans 52 based on data collected from the inputs of the control unit 38 and the fan control sub-unit 62. For example, the learning module 70 compares the energy consumption of the element 34 to that of the fans 52 using the input from the energy sensors 68 and regulates the use of the element 34 and the fans 52 based on the comparison. The learning module 70 also analyzes the other inputs and combinations of inputs and, based on the analysis, performs a variety of functions including: providing recommendations of alternative user settings and positions, orientations and directions of flow of the fans 52 that might improve energy efficiency or reduce energy use; and indicating when the element 34 and the fans 52 require service.
As an exemplary embodiment of the learning module 70, the learning module 70 can monitor and analyze the performance of the baseboard unit 2 and fans 52 and, based on the analysis, the fan control sub-unit 62 can control the position, orientation and direction of flow of the fans 52 using electronically-controlled gyroscopic mounting brackets.
As discussed above with reference to FIG. 5, the fan control sub-unit 62 may be operably connected to control at least one means for actuating a movable fan mounting bracket.
Referring to FIGS. 8-9, the baseboard unit 2 is shown with filters 72 mounted to the housing 12. The filters 72 are generally disposed proximate the openings 28, 30 to reduce the number of foreign objects and the amount of particulate matter that enters and is deposited in the housing 12. The filters 72 also reduce the amount of the particulate matter that is transmitted around the room in the air flow generated by the baseboard unit 2.
The filters 72 clean the air as the air passes through the baseboard unit 2. One advantage of filtering the air is that it reduces the likelihood that dust will be deposited on the element 34 as the air passes through the housing 12. The depositing of dust on the element 34 can act to insulate the element 34 and reduce the efficiency of the baseboard unit 2.
Referring to FIG. 10, another improved baseboard unit 2 c, according to a third embodiment of the present invention, has at least one fan 52 installed therein. In this third embodiment, the at least one fan 52 is oriented to face the axial direction of the heating and/or cooling element 34. It is understood that air injected by the fan 52 passes down the length of the element 34. In embodiments wherein the element 34 has fins protruding generally perpendicular to the injected air, it will be understood that the injected air will tend to curl around the edges of the fins, thereby establishing the “pilot flow” that enables natural convection at reduced operating temperatures.
FIGS. 11 and 12 show another improved baseboard unit 2 d having at least one fan 52 installed therein. As shown in FIG. 11, a duct or plenum 74 is installed along the length of the baseboard unit 2 d without obstructing the lower opening 30 of the housing 12. The duct 74 is shown as a generally cylindrical tube that is substantially closed, with the at least one fan 52 installed near an end of the tube for pressurizing air within the plenum. The plenum 74 includes holes 76 along its length. The holes are disposed to direct a pressurized flow of priming air from the plenum toward the working element 34 of the improved baseboard unit 2 d. At one end of the duct 74, at least one fan 52 is provided to generate air flow through the duct 74. In some embodiments, the holes 76 increase in size at the remote end of the duct 74 from the fan 52 to ensure substantially even distribution of the priming flow across the element 34 of the baseboard unit 2. However, the holes 76 can vary in size to conform to the room and the baseboard unit, as discussed herein. In some embodiments of the present invention, the fan 52 can be remotely ducted, meaning that the fan 52 is mounted to the duct 74 that is installed outside of the baseboard unit 2. In the embodiment shown in FIGS. 11 and 12, entrainment of ambient air through the lower opening 30 may augment the rated flow of the fan by a factor of between about 3:2 and about 5:1. In other words, the pressurized air priming flow provided by the fan via the openings 76 may make up only about 15% to about 30% of the total mass air flow across the working element 34. FIG. 12 shows in detail view an exemplary user interface 44, a knob for adjusting a thermostat 36 that selectively energizes a solenoid valve for admitting water to the baseboard unit 2 d.
The fans 52 can be powered by an alternative power source, such as solar, thermoelectric, hydraulic, pneumatic, piezoelectric or any other available energy source. For example, as shown in FIG. 13, the baseboard unit 2 d can include solar panels 78, which power the fan 52. The solar panels 78 can be mounted in a windowsill or the like and power the fan 52 to automatically blow air across the element 34. This provides a simple and cost effective means of improving the efficiency of the baseboard unit 2 d during daylight hours, when heating and cooling demands as well as energy consumption peak, without impacting the wiring arrangement of the baseboard unit 2 d. Other embodiments of the invention may include other “alternative” or “regenerative” power supplies. For example, it is contemplated that a thermopile may be operably mounted to a heated water working element for providing moderate DC voltage to power the fan(s).
In selected embodiments of the present invention, the duct or plenum 74 may be movably connected to the housing 12. Means for actuating the plenum 74 within the housing 12 may be operably connected for control by the fan control sub-unit 62 in response to one or more sensed parameters. Acceptable actuating means may include a toothed rack driven by a pinion of a DC stepper motor, or a pneumatic piston actuator driven by actuation of air valves. Those of ordinary skill can realize other acceptable means for actuating the plenum 74.
The present invention is easily incorporated into new baseboard units, but is equally adaptable for retrofitting already installed baseboard units of conventional design (see, e.g., FIG. 1) and other heating ventilation and air conditioning (HVAC) units. The housing 12 can also be placed in the ceiling or in a wall of the room, such as in a recess or a slit.
For instance, referring to FIG. 14, the fans 52 of the present invention can be placed partly in register with the air intake and/or outtake openings of different kinds of HVAC unit 80, such as a split air conditioning system that is located in a hole in a wall and connected to the outdoors. In such an embodiment, the fans 52 can improve the air throughput of the HVAC unit 80 (i.e., from 100 cubic feet per minute to 200 cubic feet per minute), without significantly obstructing the main flow provided by the conventional fan(s) of the HVAC unit, so as to expand the operational range of the HVAC unit 80 and improve its energy efficiency.
The fans 52 also enable the production of different designs of HVAC units 80. Referring to FIG. 15, the fans 52 of the present invention can be placed in register with a stacked baseboard system 82. The stacked baseboard system 82 includes several horizontally oriented heating and cooling elements 84 that are vertically stacked by a frame 86. Fans 52 are fitted to the frame 86 and oriented to direct air flow across each of the elements 84, or to re-direct air flow away from one or another of the elements 84. The stacked baseboard system 82 is well suited for installation in a narrow section of wall, where other baseboard units and HVAC units would not fit.
Referring to FIG. 16, another embodiment of the invention makes use of the Coanda effect to entrain room air. As shown in FIG. 16, an air tube 90 is mounted below and parallel to a working element 34. The air tube 90 is enclosed by a generally cylindrical first wall or semi-tube 92 and a generally cylindrical second wall or semi-tube 94. The first wall 92 is of greater diameter than the second wall 94. The first wall 92 includes at one end a generally circular end plate 96, which is pivotally connected with an adjacent generally circular end plate 98 of the second wall 94. At the end of the air tube 90 opposite the end plates 96, 98, a fan 52 is mounted to the generally cylindrical first wall 92. In operation, the fan 52 directs air along the air tube 90 within the first and second walls 92, 94. The air dissipates from the air tube 90 through slits 100 formed along the air tube between the first wall 92 and the second wall 94. In the embodiment as shown in FIG. 16, the air tube 90 is positioned below the working element 34 with the slits 100 directed upward toward the surfaces of the working element 34. Accordingly, air injected from the slits 100 curves around the outer surface of the second wall 94 and entrains air within the housing 12, prior to impinging on the surfaces of the working element 34. In other embodiments, the air tube 90 may be placed above the working element 34 with the slits 100 directed downward. In other embodiments the air tube 90 may be placed horizontally adjacent the working element. In select embodiments the slits 100 may be directed horizontally toward the working element 34, thus providing a priming cross-flow. In select embodiments, the inner and outer semi-tubes 92, 94 may be arranged such that one of the slits 100 directs air flow upward while the other slit 100 directs air flow downward.
FIG. 17 shows an air tube 102 according to another embodiment of the invention. The air tube 102 is enclosed by a uniform hollow cylinder 104, which has one or more slits 106 cut through it at uniform or arbitrary spacings along its length. The slit(s) 106 may be made generally within planes orthogonal to the axis of the cylinder 104, or may be diagonal or helical at an angle 108 from a plane orthogonal to the axis of the cylinder. At the proximal end of the air tube 102, a fan 52 is shown connected to introduce pressurized air into the air tube. The pressurized air then exits the air tube 102 through the slits 106. In use, the air tube 102 can be mounted below a working element 34 to induce convection of ambient air against the surfaces of the working element in a manner substantially as discussed above.
FIG. 18A shows in perspective view an air duct cover 110, according to another embodiment of the present invention. The air duct cover 110 includes a roomward duct wall 112, an inward duct wall 114, a duct plenum 116 enclosed between the roomward and inward duct walls, an upper outlet slot 118 and a lower outlet slot 120 through which air can exit the plenum, and a fan 52 that draws room air into the plenum 116. The lower outlet slot 120 is upwardly angled such that, when the air duct cover 110 is installed onto a conventional baseboard unit 2 in place of the conventional front surface 22, air exiting the lower outlet slot induces Coanda-type entrainment of room air onto and through the working element 34, thereby enhancing natural convection. FIG. 18B shows a sectional view of the air duct cover 110.
FIG. 19 shows another embodiment of the present invention, in which a planar array of working elements 34 are disposed adjacent to and staggered from a planar array of air tubes or plenums 90. The plenums 90 are pressurized with air by means not shown, and direct the pressurized air as priming flows onto the working elements 34. The priming flows induce a main flow of air through both of the planar arrays. The main flow of air may be provided via an opening of an enclosure surrounding the working elements, or by other means such as by a main fan.
It should be understood that the foregoing description is only illustrative of the invention. Those skilled in the art can devise various alternatives and modifications without departing from the broader aspects of the present invention.
For instance, it should be appreciated that the baseboard units shown in FIGS. 4-18B are merely exemplary of a wide range of heat exchangers known in the art. The present invention can also be applied to radiator covers or boxes and other housings used to protect or hide any working element of a heat exchanger.
It should also be appreciated that the exact configuration of the fans mounted to a particular baseboard unit is dependent upon the overall configuration of heating and/or cooling devices within each room within the household; the size and shape of the room in which the baseboard unit(s) is installed; the size, shape, type and configuration of baseboard unit(s); and the data collected by the learning module from the operation of the baseboard unit having the fans.
In an alternative embodiment of the present invention, a priming air flow may be drawn at a position downstream in the convection cycle, rather than being supplied at a position upstream in the convection cycle.
In an alternative embodiment of the present invention, any or each fan can be replaced by other conventional or after-developed means for supplying a pressurized priming air flow, for example, a compressor, a vacuum, or other air pump. For example, in each embodiment shown as including an air tube, duct cover, or similar plenum for directing pressurized air to induce the movement of ambient air, air within the plenum may be pressurized by any conventional or after-developed means without departing from the scope of the invention. Alternatively, means for providing a priming air flow may include a structure for diverting or siphoning off a portion of a forced air flow supplied by a main fan. Generally, an apparatus according to the present invention may include various means for inducing a priming air flow toward or onto the surfaces of the working element within the baseboard unit, so long as a main natural convective flow, or a main forced flow, is not thereby obstructed. For example, while the illustrated embodiments are limited to natural convective flow, the invention is not meant to be so limited; in particular, embodiments of the invention are contemplated in which the priming flow enhances forced convection by a main fan.
In an alternative embodiment of the present invention, the energy generated by the alternative power source, such as the solar panels, can be diverted to power the control unit, the fan control sub-unit and other electronic devices in the household, or be returned to the electric grid.

Claims

1. An apparatus for enhancing convection of air at a working element of a heat exchanger, comprising:

means for providing a main flow of air directed toward the working element; and

means for producing a priming flow of pressurized air that impinges upon the working element to disrupt a stagnant boundary layer adjacent the working element.

2. An apparatus for enhancing natural convection of ambient air at a working element of a heat exchanger, comprising:

a substantially closed and elongated plenum extending generally parallel to and proximate the working element, the plenum being filled with pressurized air and having at least one opening disposed such that a first quantity of the pressurized air exits the opening as a priming air flow and induces a second quantity of ambient air to flow as a main air flow onto and across a surface of the working element.

3. A method for enhancing convection at working element of a heat exchanger, comprising:

supplying at least one pressurized priming air flow onto the working element, substantially without obstructing access of a main air flow to the working element, whereby the priming air flow induces an increase of the main air flow adjacent to the working element.

4. An apparatus as claimed in claim 1 or claim 2, further comprising:

one or more fans for producing the pressurized priming air flow.

5. An apparatus as claimed in claim 4, wherein each of the fans takes suction on ambient air.

6. An apparatus as claimed in claim 4, wherein at least one of the one or more fans is movably connected to the heat exchanger and is automatically movable in response to a sensed parameter.

7. An apparatus as claimed in claim 2, wherein the plenum is provided as a tube, the at least one opening is provided as a slot in the wall of the tube, and a fan is mounted to an open end of the tube for filling the plenum with pressurized air,

the plenum being disposed below and generally coextensive with the working element.

8. An apparatus as claimed in claim 2, wherein the plenum is formed by a generally cylindrical first semi-tube of a first diameter and by a generally cylindrical second semi-tube of a diameter smaller than the first diameter,

each of the first and second semi-tubes having a capped end and an open end, the capped ends of the first and second semi-tubes being fastened together,

the second semi-tube being nested within and generally radially opposed to the first semi-tube thereby forming the at least one opening as at least two slots along the length of the plenum.

9. An apparatus as claimed in claim 8, wherein the first and second semi-tubes are additionally fastened together at intervals along the length of the plenum to form a plurality of slots along the length of the plenum.

10. An apparatus as claimed in claim 8, wherein the capped ends of the first and second semi-tubes are pivotally fastened together.

11. An apparatus as claimed in claim 2, wherein the plenum is provided within a portion of a housing generally enclosing the working element, wherein the portion of the housing enclosing the plenum is separated from the remainder of the housing by at least one gap that provides access of ambient air to the working element, and wherein the at least one opening of the plenum is disposed adjacent to the at least one gap.

12. An apparatus as claimed in claim 11, wherein a fan is mounted in a wall of the plenum facing outward from the working element for producing pressurized air in the plenum.

13. An apparatus as claimed in claim 1, wherein the heat exchanger is a baseboard unit enclosed by a housing,

the means for providing a main flow include an upper opening and a lower opening of the housing, and

the means for producing a priming flow include a plurality of fans spaced along at least one of the lower opening or the upper opening.

14. A method as claimed in claim 3, further comprising:

sensing at least one parameter of the working element; and

comparing the at least one parameter to a pre-determined threshold; and

adjusting the at least one pressurized priming air flow to control impingement of the main air flow onto the working element, based on the comparison.

15. A method as claimed in claim 14, wherein adjusting the at least one pressurized priming air flow includes repositioning a fan.

16. A method as claimed in claim 14, wherein adjusting the at least one pressurized priming air flow includes repositioning an opening of a priming air flow plenum.