US3618659A

US3618659A - Environmental conditioning system and method

Info

Publication number: US3618659A
Application number: US25834A
Authority: US
Inventors: Davis I Rawal
Original assignee: DAVIS I RAWAL
Current assignee: DAVIS I RAWAL
Priority date: 1970-04-06
Filing date: 1970-04-06
Publication date: 1971-11-09
Anticipated expiration: 1988-11-09

Abstract

An environmental conditioning method removes stale air and replaces it, at least in part, with fresh air at volumetric rates that are substantially the same. The stale air from the room is delivered to a return damper with a kinetic energy level of substantially zero, and the volumetric rate of airflow from and to the room is substantially independent of the volume of air removed and replaced. A modular damper unit may be employed, which provides heat exchangers for conservation of heat energy, and the system provided is readily adapted for centralized, overall environmental conditioning by the incorporation of heating, cooling, cleaning and humidity control means therein.

Description

United States Patent [72] Inventor Davis I. Rawal 105 White St., Waterbury, Conn. 06710 [21] Appl. No. 25,834 [22] Filed Apr. 6, 1970 [45] Patented Nov. 9, 1971 [54] ENVIRONMENTAL CONDITIONING SYSTEM AND METHOD 10 Claims, 7 Drawing Figs.

[52] US. Cl 165/1, 165/3,165/16, 165/59, 165/107 [51] Int. Cl F28 [50] Field of Search 165/1-3, 16,59,66, 106, 107

[ 56] References Cited UNITED STATES PATENTS 1,895,444 1/1933 Cassell 165/3 X 2,825,210 3/1958 Carr 165/66 X Primary Examiner-Carroll B. Dority, J r. A!t0rneyPeter L. Costas ABSTRACT: An environmental conditioning method removes stale air and replaces it, at least in part, with fresh air at volumetric rates .that are substantially the same. The stale air from the room is delivered to a return damper with a kinetic energy level of substantially zero, and the volumetric rate of airflow from and to the room is substantially independent of the volume of air removed and replaced. A modular damper unit may be employed, which provides heat exchangers for conservation of heat energy, and the system provided is readily adapted for centralized, overall environmental conditioning by the incorporation of heating, cooling, cleaning and humidity control means therein.

PATENTEDunv 9 Ian 3151815 59 sum 1 [IF 3 REHEATING UNlT I30 I'ZBCOOLINO UNIT HUMIDIFIER I32 I26 FILTER H6 SECONDARY SUPPLY BLOWER \)34 R MARY RETURN BLOWER IZ4AIR CLEANER DAMPER UNIT l i :g s l M ifi jaa i FIG.7

//v VEN TOR [)A W5 1. A 4 h/AL ATTORNEY ENVIRONMENTAL CONDITIONING SYSTEM AND METHOD BACKGROUND OF THE INVENTION In the design of effective ventilation systems for homes, commercial buildings, and the like, the basic objective is normally to attain a steady state condition wherein the volumetric flow and exchange rates of air maintain the desired ambient conditions. Generally, present systems simply rely upon fans and blowers to achieve air exhaust, as a result of which the mere act of opening a door or a window affects the operation of the system and changes the ventilation characteristicsr moreover, such systems tend to induce drafts and often undesirably affect conditions in areas adjacent to that being ventilated. A separate makeup air unit may be installed to counteract these effects and to ensure positive ventilation, but this tends to be costly and inconvenient since the fresh air must be heated, cooled, or otherwise conditioned to maintain the area at a comfortable temperature, humidity level, etc.

These problems are well known, and various attempts have been made to solve them. For example, devices are described in the art which may be used to recycle a portion of the room air in an effort to conserve heat energy. However, so far as is known, no system has been heretofore designed that permits a wide latitude of variation in the proportion of air recycled (or conversely, exhausted), while at the same time maintaining a substantially constant flow rate of air through the system, or that operates in such a manner substantially independently of the availability of air access points, such as through windows, doors, etc.

Accordingly, the primary object of the present invention is to provide a novel environmental conditioning method wherein all, none, or a portion of the air exhausted from an area may be replaced with fresh air without appreciable afiect upon the volumetric flow rate through the conditioned area.

It is also an object of the invention to provide such method wherein the rate of air removal is substantially the same as the rate of return, and the rate of ventilation is substantially independent of changes in the positions of doors, windows, etc. within the ventilated area.

Another object is to provide a modular damper unit that may be employed therein to control the condition of the air within an area and to furnish air at a temperature approximating ambient, in an economical manner by conservation of the heat content of air exhausted therefrom.

SUMMARY OF THE INVENTION It has now been found that the foregoing and related objects can be readily attained in a method of environmental conditioning wherein stale air is continuously removed from a conditioned area at a preselected volumetric rate, and delivered through a conduit to the vicinity of a variable return damper at a kinetic energy level of substantially zero. A variable exhaust opening in the conduit upstream of the damper is controlled to discharge an appropriate volume of the stale air therethrough, and the return damper is controlled to permit recycle of the remainder of the stale air therethrough and into a second conduit communicating with the conditioned area. A variable intake opening that is located in the second conduit downstream of the damper and in the vicinity thereof is controlled to admit therethrough a volume of fresh air that is substantially equal to the volume of stale air that is discharged. The volume of fresh air and the air recycled is withdrawn from the vicinity of the damper and a mixture thereof is continuously delivered to the conditioned area through the second conduit; the volumetric rate of delivery is substantially the same as the preselected volumetric rate of removal of stale air, and is substantially independent of the volume of air that is discharged.

In the preferred method, the stale air and the fresh air are at different temperatures, and the temperature desired in the mixture delivered to the conditioned area is intermediate thereof. The volume of air discharged and admitted is controlled to provide proportions of fresh and recycle air in the mixture that are appropriate to attain the desired temperature therein. In such a case, the method may include the additional step of extracting a portion of the heat energy from whichever one of the discharged and admitted volumes is warmer, and transferring the heat energy to the cooler one thereof. A temperature dependent signal may be generated for automatic control for the volume of air discharged and admitted, and the stale air may be cleaned to remove pollutants therefrom before it is delivered to the return damper and before the volume thereof is discharged.

The present invention also provides an environmental conditioning system utilizing a modular damper unit that comprises a housing providing a flow chamber that has an inlet opening for receiving air from a conditioned area, an outlet opening for returning air thereto, an exhaust opening for discharging air from the system, and an intake opening for drawing fresh'air thereinto. A return damper in the housing substantially divides the chamber into two parts, the inlet and exhaust openings communicating with one of the parts and the outlet and intake openings communicating with the other part thereof; direct airflow between the parts is substantially blocked by the damper in the closed position thereof. At least one additional damper in the housing that overlies the exhaust and intake openings substantially blocks airflow therethrough when in the closed position thereof. Control means is provided to drive the dampers and to operatively couple them together in such a manner that when one of the dampers is moved from the closed position to the open position thereof, the other one of the dampers is moved from the open position to the closed position thereof. The unit also includes a heat exchanger that is comprised of a heat exchange member overlying each of the exhaust and intake openings, and a pump for circulating heat exchange fluid through the heat exchanger from one of the members to the other. Heat is thereby extracted from air passing through one of the exhaust and intake openings and is dissipated to cooler air passing through the other one thereof, when the additional damper is in an open position.

In the preferred embodiments, the system additionally includes an upstream conduit connected to the inlet opening of the flow chamber for conveying air thereto, and a downstream conduit connected to the outlet opening of the flow chamber for conveying air therefrom. A blower in the upstream conduit induces air flow toward the damper unit and a blower in the downstream conduit induces air flow therefrom, the upstream blower being sized and powered to deliver air to the return damper at a kinetic energy level ofsubstantially zero. The dampers and openings are cooperatively dimensioned and configured so that the downstream blower draws air at substantially the same volumetric rate through the return damper, when the additional damper is in closed position, and through the intake opening, when the return damper is in the closed position thereof. Most desirably, the blowers are relatively sized and powered to provide substantially the same volumetric rate of air flow at the outer extremities of the upstream and downstream conduits. The system may include a temperature sensor having means for generating a temperature dependent signal, the control means in the damper unit being automatically responsive to the signal from the generating means to drive the dampers in such a manner as will tend to substantially maintain a desired preselected temperature in air flowing past the extremity of the downstream conduit. It may also include an electrostatic precipitator upstream of the exhaust outlet to ensure that recycled and exhausted portions of the air from the conditioned area contain a reduced concentration of pollutants.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a damper unit embodying the present invention, a portion of the housing being broken away to show the inner construction thereof;

FIG. 2 is a schematic elevational view of an installed environmental conditioning system incorporating such a damper unit;

FIG. 3 is a plan view of the system of FIG. 2;

FIGS. 4, 5 and 6 are side elevational views of the damper unit illustrated in FIG. 1, to a reduced scale, showing positions to which the dampers therein may be adjusted and illustrating the air flow configurations resulting therefrom; and

FIG. 7 is an elevational view of a second system incorporating the type of damper unit illustrated in FIG. 1 and providing a unified overall environmental conditioning system.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS Turning now in detail to FIG. 1 of the appended drawings, a damper unit embodying the present invention and generally designated by the numeral 10 is illustrated therein, and comprises a rectangular housing 11 having an interior vertical partition 12 which divides it transversely into a flow chamber portion 14 and a central chamber portion 16. Each of the sidewalls 18 thereof has a large

rectangular opening

20, 20 therethrough, providing an inlet to, and an outlet from, the flow chamber portion 14, respectively; the openings 20, 20' have flanges 22 projecting outwardly thereabout to facilitate attachment to connecting conduits in a conventional manner. A longitudinal vertical partition, generally designated by the numeral 24, divides the unit 10 between one end wall 26 and the transverse partition 12, and consists of a solid lower portion 26 and a vertical return damper assembly 28 thereabove. The damper assembly 28 consists, in a conventional manner, of a multiplicity of pivotally mounted horizontally extending blades or slats 30, the lowermost one 30 of which has an axially extending shaft 32 on which is secured a drive sprocket 34. The remaining slats 30 are operatively connected to the slat 30' (by means not shown) so that pivotal movement thereof, through the sprocket 34 and shaft 32, is transmitted to all of the slats 30 to pivot them concurrently.

The bottom wall 36 of the housing 11 has formed therein, on one side of the longitudinal partition 24, an exhaust opening 38 and, on the opposite side of the partition 24, a makeup or intake In lieu of an existing fan (such as 78 in FIG. 2) thepresentsystem includes a primary return blower 118, which serves to draw the stale air out of the room 120 and through both the conduil22 and the electrostatic air cleaner 124, and to deliver it with substantially no kinetic energy at the damper 28 of the unit 10. Theblower 118 and the air cleaner 124 are supported on the stand 114 on the upstream or exhaust side of the damper unit 10, and on thedownstream or intake side thereofa filter 126, a cooling unit 128, a reheating unit 130, a humidifier 132 and secondary supply blower 135 are supported in serial registry. As in the system previously described, the blower 134 draws fresh and.or recycle air through the damper unit 10, and in the present system it thereafter draws the air through the cooling unit 128, reheating unit 130 and humidifier 132; finally, the blower 134 supplies the air to the room 120 through the return conduit 136. Accordingly, thisystem may berelied upon forcomplete environmental control, having not only the capcbility of totally exhausting, totally recycling, or partially recycling stale room air and replacing it with a desired proportion offresh air, but it may also be used for primary temperature andhumidity control; moreover, all of these functions may be automatically controlled and balanced for optimum environmental conditionsby suitable and appropriately located sensors. It will beapparent that in this embodiment, the reheating unit 130 is an electric, steam or gas fired device, and that the cooling unit may operate on conventional air conditioner" principles. Other devices may be included therein, and the possibilites in this regard willbeapparent to those skilled in the art.

Normally, the systems of the invention will be designed to provide the particular volumetric flow rate of air through the conditioned area that has been determined to best afford the desiredlevel of ventilation; thimay be accomplished by balancing the capacity of the blowers against the static head or resistance oftye syetem. As has been pointed out previously, it

ismost advantageous to deliver the air from the room to the return damperwith a kinetic energy approaching, or very nearly, zero. This assumes that such will also be the prevailing condition of the outsideair, so that at the return baffle thedownstream blower will draisubstantially the same volume of air per unit of time, regardless of whether it draws the air from outside or from theupstream side of the return damper.

These objectives can most simply be attained by dimensioning and configuring the dampers and the openings covered thereby so that the unobstructed areas thereof are of approximately the same size. In such a case, balancing of the system t achieve a constant flow rate of air and an equal exhaust and return rate to the room will be simplified considerably. As a practical manner, if the unobstructed areas are no unduly small, in many instanceteh specific size thereof becomes of secondary importance. In any event, the simplest manner of design andinstallation will usually entail a rough approximation of the specifications necessary to achieve adequate ventilation and, after installation, registration of the drivepower for the blowers until the system is satisfactorily balanced. It should be appreciated that the term blowers" has been used herein for the sake of convenience and is intended to encompass any device that may be appropriate to induce airflow; ithas also been usedwithout regard for whether its primary function is one f suction r0 of blowing of air. Similarly, conservation of heat content has been usedin the sense that the negative of deficiency of heat energy of air cooled relative to ambient may be conserved, just as may the real energy of relatively warm air. In addition, although it has been stressed that the total volumetric rate of airflow through the return and additional dampers shouldbe substantially the same regardless of which isopen and which is closed the damper design will usually be such as to cooperatively afford substantially that rate when both of them arein appropriate partially open positions.

It will be appreciated for the foregoing that the present invention embodies the novel concept of effecting an exchange of air by exhausting stale air at substantially the same energy level as thatat which the fresh air, used for replacement thereof, exists. Thus, the ambient air is assumed to have a kinetic energy level of substantially zero and, by delivering the stale air to the return dampera at about the same energy level, the downstream blower will remove the same volume of air therefrom regardless of whether the air removedconsists of fresh air, stale air, or a mixture containing any proportion thereof. Since this result may generally be realized even though the staleair arrives at the return damper with a level of kineticenergy somewhat above zero, the term kinetic energy level ofsubstantially zero should be understood to mean that the stale air would arrive at the damper but eave little or no tendency to pass therethrough in the absence of the effect of the downstream blower thereon.

Thus, it can be seen that the present invention provides an environmental conditioning method wherein all, one, or a portion of the air exhausted from an area may be replaced with fresh air without appreciable affect upon the volumetric flow rate through the conditioned ares. In the method, the rate of air removal is substantially the same as the rate of return thereof and the rate of ventilation is substantially independent of changes in the positions ofdoors, windows, etc. within the ventilated area. A modular damperunit controls the condition of the air within an area to furnish air a a temperature approximating ambient, in an economical manner by conservation of the heat ocntent of air exhausted from the conditioned area.

Having thus described the invention l CLAIM:

I. In a method of environmental conditioing, the steps comprising:

A. continuously removing staleair from a conditionedarea at a preselected volumetric rate and deliveringitthrough a conduit to the vicinity of a variablereturn damper at a kinetic energy level of substantially zero;

B. controlling a variableexhaust opening in saiconduit upstrea of said daper t discharge an appropriate volume f said stale air therethrugh;

C. controlling said return damper t permit recycle of the remainder of said stale air therethrough and into a second conduitcommunicating with said conditioned area;

D. controlling a variableintakeopenin, located in said second conduit downstream of said damper and in the vicinity thereof, to admit therethrough a volume offresh air substantially equal to said volume f stale air discharged; and

E. withdrawing said volume of fresh air and said recycle air from the vicinity of said damper and continuously delivering a mxiture thereof to said conditioned area through said second conduit at substantially said preselected volu metric rate, said volumetric rate being substantially independent of said volume of air discharged.

2. The method of claim 1 wherein said stale air an saidfresh air are at different temperatures, wherein wherein the temperature desired in saidmixture is intermediate thereof, and wherein said volume of air discharged and admitted is controlled to provide proportions of fresh andrecylce air in said mixture appropriate to attain said desired temperature therein.

3. The method of claim 2 including the additional step of extracting a portion of the heat energy from the warmer of said discharged volume and said admitted volume, and transferring saidheat energy to the cooler one thereof.

4. The method of claim 2 additionally including the step of generating a temperature dependent signal responsive to the temperature in said conditioned area has been inserted for automatic control of said volume of air discharged and admitted.

5. The method of claim 1 including the additional step of cleaning said stale air to remove pollutants therefrom before delivery to said return damper anddischarge of said volume thereof.

6. in an environmental conditining system, a modular damper unit comprising: A. a housing;

B. a flow chamber in said housing having an inletopening for receiving air from a conditioned area, an outlet opening forreturning air thereto, an exhaust openingfor discharging air from said system, and an intake opening for drawing fresh air thereinto;

C. a return damper in said housing substantially dividing said chamber into two parts, said inlet and exhaust openings communicating with one of said parts and said outlet and intakeopenings communicating with the other part thereof, direct air flow between said parts being substantially blocked by said damper in the closed position thereof;

D. at least one additional damper in said housing overlying said exhaust and intake openings, airflow therethrough being substantially blocked by said additional damper in the closedposition thereof;

E. control means for driving said dampers anoperatively coupling them together in such a manner thatwhen one of said dampers is moved from said closedposition to the open position thereof the other one of said dampers is moved from the open position to said closedposition thereof; an

F. a heat exchanger comprising aheat exchangemember overlying each of said exhaust and intakeopeningsand a pump for circulating a heat exchange fluid through said heat exchanger for ne of said members t the there whereby heat is extracted from airpassingthrugh one of saidexhaust andintakeopenings and idissipated t cooler air passing through the other one thereof, when said additional damper is in an open position.

7. The system of claim 6 additionally including: an upstream conduit connected to said inlet opening of said flow chamber for conveying air thereto; a downstream conduit connected to said outlet opening of said flow chamber for conveying air therefrom; a blower in said upstream conduit forinducing airflow toward said unit; and a blower in said downstream conduit forinducing airflow from said unit; said upstrea blwer being sized andpowered to deliver air to said return damper at a kinetic energy level of substantially zer, and saiddampers and openings being cooperatively dimensioned and configured for said downstream blower to draw airat substantially the samevolumetric rate through said return damper when said additional damper is in closed position and through said intake opening when saidreturn damper is in said closedposition thereof.

8. The system of claim 7 wherein said blowers are relatively sized andpowered to provide substantially the same volumetricrate ofairflow at the outer extremities of said upstream and dwnstream conduits.

9. The system of claim 8 including a temperature sensorhaving means for generating a temperature dependent signal, said control means being autoatically responsive to the signal from saidgenerating means to drive said dampers in such a manner as will tendto substantially maintain a desired preselected temperature in air flowing past the said extremity of said downstream conduit.

10. The system of claim 8 additionally including an electrostaticprecipitator upstream of said exhaust outlet t ensurethatrecycled and exhaustedportions of the air from the conditioned area contain a reduced concentration ofpollutants. opening 40. Each of these

openings

38, 40 is covered by a horizontal damper assembly 42, comprised of a multiplicity of pivotally mounted, operatively connected, horizontally extending slats 44, the inner ones 44' of which have axially extending shafts 46 on which are secured drive sprockets 48. A motor 50 is supported upon the bottom wall 36 of the housing 11, and it has a shaft 52 with a sprocket 54 affixed adjacent the outer end thereof. A common drive chain 56 is engaged over each of the

sprockets

34, 48, 54, so that actuation of the motor 50 simultaneously operates all of the

dampers

28, 42.

Heat exchanger members, generally designated by the numeral 58, extend horizontally over each of the dampers 42, and consist of a multiplicity of thin vertical radiator fins 60, extending between the vertical wall 24 and the sidewalls l8, and a continuous coil 62 that is convoluted to provide elements 64 passing longitudinally back and forth through each of the members 58. The elements 64 of one of the heat exchanger members 58 are connected to those of the other by a central element 66, and the opposite ends thereof are connected to an electrically operated pump 68 that is supported upon the bottom wall 36 of the housing 11. As will be ap parent, heat exchange fluid may be forced through the tube 62 from one heat exchanger member 58 to the other by operation of the pump 68, as will be more fully explained hereinafter.

Turning now to FIGS. 2 and 3 of the drawings, the damper unit 10 hereinbefore described is shown in a kitchen ventilating system, which may in part utilize existing equipment. Thus, the kitchen 70 contains a cooking range 72, above which is installed a hood 74 for the collection of grease, fumes and the like. A removable filter 76 is supported within the hood 74, and a fan 78 is mounted thereabove to withdraw the stale air through the filter 76 and out of the room 70 through the hole 80 provided in the roof 82 thereof. The damper unit 10 is provided with a depending baffle 81 between the exhaust opening 38 and makeup opening 40 thereof, and it is supported over the roof 82 upon a suitable angle stand 84. The stand 84 also supports a blower 86 and an electrostatic cleaner 88, the former having a removable weather cap 89 thereon and being connected to the outlet opening 20' from the flow chamber portion 14 of the housing 10, and the latter being connected to the inlet opening 20 thereof. A plenum chamber 90 is mounted directly over the roof hole 80, and it has connected to it a short horizontal conduit 92 directed toward the electrostatic cleaner 88; interposed between the cleaner 88 and the conduit 92 is a wash manifold 94, used for periodic washing of the electrostatic cleaner 88. An angled conduit 96 is connected to the outlet side of the blower 86 with the vertical leg 98 thereof passing through a second hole 100 in the roof 82 and a curb 102 thereabove, the curb 102 having a suitable protective flange or skirt 104 extending about it. The leg 98 of the conduit 96 opens into a horizontally extending duct 106 that has a multiplicity of outlet registers 108 spaced along its length. A wall-mounted thermostat 110 senses the temperature in the kitchen 70 and controls operation of the ventilating system in a manner to be described.

In operation of the system depicted in FIGS. 2 and 3, the fan 78 draws stale air upwardly from the kitchen 70 through the filter 76, and delivers it through the electrostatic cleaner 88 to the inlet side of the damper unit 10, preferably so that it arrives thereat with substantially no kinetic energy. Thus, the fan 78 is preferably sized and powered sufi'lciently to just overcome the static resistance of the exhaust portion of the system upstream of the damper 28. Similarly, the blower 86 is sized and powered to overcome the static resistance of the makeup portion on the opposite or downstream side of the system, and to equalize the pressure in the kitchen 70 by providing a volumetric flow of makeup air through the registers 108 sufficient to just balance the vacuum created by the fan 78. In this manner, a steady state condition can be attained substantially without drafts, even though the positions of kitchen doors and windows be altered.

Depending upon the temperature of the outside air, and with particular reference to FIGS. 4-6 of the drawings, the position of the dampers in the damper unit may be automatically controlled to maintain a desired temperature within the room, in an economical manner and without creating undesirable drafts therethrough. In FIG. 4, the slats 30 of the vertical bypass damper assembly 28 are aligned horizontally in fully open position, and the slats 44 of the horizontal damper assemblies 42 are at right angles to one another so that the edges of adjacent slats 44 are in contact to close the assemblies 42. As a result, all of the air from the room 70 is recycled and no fresh air is taken in, thus maintaining the room temperature with a minimum level of heat loss or gain, as is desirable to conserve the energy needed to heat or cool the room, as the case may be.

In FIG. 5, the converse situation is depicted wherein the edges of the slats 30 are in contact to close the damper assembly 28, and the slats 44 are aligned vertically in fully open position of the dampers 42. It will be apparent that in these positions the air withdrawn from the room 70 is totally expelled and replaced by fresh outside air; this condition is appropriate when the temperature outside the room is substantially the same as that which it is desired to maintain therewithin.

Finally, FIG. 6 illustrates one of an infinite number of intermediate arrangements of damper slats wherein each of the

damper assemblies

28, 42 is partially open. This permits a portion of the stale air to be exhausted and replaced with fresh air, the remainder thereof being recycled to the room. Such an arrangement is appropriate under a variety of circumstances, one example of which occurring when the heat withdrawn over a cooking range would unduly raise the room temperature if totally recycled; dilution thereof with cooler outside air may be relied upon to maintain the temperature at a desirable level, while at the same time freshening the atmosphere in the room.

It will be appreciated that the position of the

dampers

28, 42 is thermostatically controlled by the thermostat 110, which is designed to transmit (such as through a proportioning device, not shown) an appropriate signal to the motor 50 that drives the

slats

30, 44. Although the thermostat 110 may be wall mounted, as shown in FIG. 2, it may be more efficient, in terms of accuracy and responsiveness of control, to mount it within the duct 106 or conduit 96 since the air therein will be at virtually one temperature and not subject to dilution, as would normally be the case within the room 70.

It will also be appreciated that since the stale air from the room is delivered to the damper unit at a substantially zero kinetic energy level, the volume of air recycled by the blower 86 will be independent of the position of the

dampers

28, 42; i.e., both room air and fresh air at the damper unit will be at substantially the same pressure. Accordingly, if the fan 78 and blower 86 are properly sized and powered, the system will operate virtually draft-free, regardless of the position of dampers, doors, windows, etc.

The heat exchanger members 58 shown in FIG. 1 of the drawings are of significant value in obtaining the maximum effectiveness and economy from the damper unit 10. It will be apparent that in pumping the heat transfer fluid from one of the members 58 to the other, the heat from the warmer air passing through one side of the damper unit can be recovered and dissipated to the cooler air passing through the other side thereof. Thus, when the exhaust air flowing through the inlet opening 20 and the exhaust opening 38 of the unit 10 is at an elevated temperature relative to outside air, the heat exchanger members 58 may be used to recover its heat and transfer it to the fresh air passing through the intake opening 40 and outlet opening 20' thereof. Similarly, if the inside air is cooler than the outside air, the members 58 may be used to cool the incoming air, and thereby reduce the load upon the equipment used to cool the room. Accordingly, the principal benefit derived from operation with heat exchange is the capability of drawing a significant quantity of fresh air into the room while at the same time maintaining the temperature therein with a minimum increase in the demand upon the heating or cooling equipment.

Turning finally to FIG. 7, the system therein illustrated is suitable for installation where no previous exhaust system was present, and it incorporates a number of features absent from the system depicted in FIG. 2. The damper unit 10, which is supported over the roof 112 upon a suitable support stand 114, is once again the heart of the system and is virtually the same as that shown in FIG. 1. However, in the present unit 10 an alternate exhaust opening is provided by the duct I16 (illustrated in phantom line) which is positioned at the top of the unit remote from the intake opening 40 at the bottom thereof. This renders the baffle 81 unnecessary since it ensures that the exhaust air will not be drawn immediately back into the unit; accordingly, when the duct 116 replaces the exhaust opening 38, the baffle 81 may be eliminated.

In lieu of an existing fan (such as 78 in FIG. 2) the present system includes a primary return blower 118, which serves to draw the stale air out of the room 120 and through both the conduit 122 and the electrostatic air cleaner 124, and to deliver it with substantially no kinetic energy at the damper 28 of the unit 10. The blower 118 and the air cleaner 124 are supported on the stand 114 on the upstream or exhaust side of the damper unit 10, and on the downstream or intake side thereof a filter 126, a cooling unit 128, a reheating unit 130, a humidifier 132 and secondary supply blower 134 are supported in serial registry. As in the system previously described, the blower 134 draws fresh and/or recycle air through the damper unit 10, and in the present system it thereafter draws the air through the cooling unit 128, reheating unit and humidifier 132; finally, the blower 134 supplies the air to the room 120 through the return conduit 136. Accordingly, this system may be relied upon for complete environmental control, having not only the capability of totally exhausting, totally recycling, or partially recycling stale room air and replacing it with a desired proportion of fresh air, but it may also be used to primary temperature and humidity control; moreover, all of these functions may be automatically controlled and balanced for optimum environmental conditions by suitable and appropriately located sensors. It will be apparent that in this embodiment, the reheating unit 130 is an electric, steam or gas fired device, and that the cooling unit may operate on conventional air conditioner principles. Other devices may be included therein, and the possibilities in this regard will be apparent to those skilled in the art.

Normally, the systems of the invention will be designed to provide the particular volumetric flow rate of air through the conditioned area that has been determined to best afford the desired level of ventilation; this may be accomplished by balancing the capacity of the blowers against the static head or resistance of the system. As has been pointed out previously, it is most advantageous to deliver the air from the room to the return damper with a kinetic energy approaching, or very nearly, zero. This assumes that such will also be the prevailing condition of the outside air, so that at the return baffle the downstream blower will draw substantially the same volume of air per unit of time, regardless of whether it draws the air from outside or from the upstream side of the return damper.

These objectives can most simply be attained by dimensioning and configuring the dampers and the openings covered thereby so that the unobstructed areas thereof are of approximately the same size. In such a case, balancing of the system to achieve a constant flow rate of air and an equal exhaust and return rate to the room will be simplified considerably. As a practical manner, if the unobstructed areas are not unduly small, in many instances the specific size thereof becomes of secondary importance. In any event, the simplest manner of design and installation will usually entail a rough approximation of the specifications necessary to achieve adequate ventilation and, after installation, registration of the drive power for the blowers until the system is satisfactorily balanced. It should be appreciated that the term blowers has been used herein for the sake of convenience and is intended to encompass any device that may be appropriate to induce airflow; it has also been used without regard for whether its primary function is one of suction or of blowing of air. Similarly, conservation of heat content" has been used in the sense that the negative or deficiency of heat energy of air cooled relative to ambient may be conserved, just as may the real energy of relatively warm air. In addition, although it has been stressed that the total volumetric rate of airflow through the return and ad ditional dampers should be substantially the same regardless of which is open and which is closed, the damper design will usually be such as to cooperatively afford substantially that rate when both of them are in appropriate partially open positions.

It will be appreciated from the foregoing that the present invention embodies the novel concept of effecting an exchange of air by exhausting stale air at substantially the same energy level as that at which the fresh air, used for replacement thereof, exists. Thus, the ambient air is assumed to have a kinetic energy level of substantially zero and, by delivering the stale air to the return damper at about the same energy level, the downstream blower will remove the same volume of air therefrom regardless of whether the air removed consists of fresh air, stale air, or a mixture containing any proportion thereof. Since this result may generally be realized even though the stale air arrives at the return damper with a level of kinetic energy somewhat above zero, the term kinetic energy level of substantially zero should be understood to mean that the sale air would arrive at the damper but have little or no tendency to pass therethrough in the absence of the effect of the downstream blower thereon.

Thus, it can be seen that the present invention provides an environmental conditioning method wherein all, none, or a portion of the air exhausted from an area may be replaced with fresh air without appreciable affect upon the volumetric flow rate through the conditioned area. In the method, the rate of air removal is substantially the same as the rate of return thereof and the rate of ventilation is substantially independent of changes in the positions of doors, windows, etc. within the ventilated area. A modular damper unit controls the condition of the air within an area to furnish air at a temperature approximating ambient, in an economical manner by conservation of the heat content of air exhausted from the conditioned area.

Having thus described the invention, 1 claim:

1. In a method of environmental conditioning, the steps comprising;

A. continuously removing stale air from a conditioned area at a preselected volumetric rate and delivering it through a conduit to the vicinity of a variable return damper at a kinetic energy level of substantially zero;

B. controlling a variable exhaust opening in said conduit upstream of said damper to discharge an appropriate volume of said stale air therethrough;

C. Controlling said return damper to permit recycle of the remainder of said stale air therethrough and into a second conduit communicating with said conditioned area;

D. controlling a variable intake opening, located in said second conduit downstream of said damper and in the vicinity thereof, to admit therethrough a volume of fresh air substantially equal to said volume of stale air discharged; and

E. withdrawing said volume of fresh air and said recycle air from the vicinity of said damper and continuously delivering a mixture thereof to said conditioned area through said second conduit at substantially said preselected volumetric rate, said volumetric rate being substantially independent of said volume of air discharged.

2. The method of claim 1 wherein said stale air and said fresh air are at different temperatures, wherein the temperature desired in said mixture is intermediate thereof, and wherein said volume of air discharged and admitted is controlled to provide proportions of fresh and recycle air in said mixture appropriate to attain said desired temperature therein.

3. The method of claim 2 including the additional step of extracting a portion of the heat energy from the warmer of said discharged volume and said admitted volume, and transferring said heat energy to the cooler one thereof.

4. The method of claim 2 additionally includingthe step of generating a temperature dependent signal responsive to the temperature in said conditioned area for automatic control of said volume of air discharged and admitted.

5. The method of claim 1 including the additional step of cleaning said stale air to remove pollutants therefrom before delivery to said return damper and discharge of said volume thereof.

6. In an environmental conditioning system, a modular damper unit comprising:

A. a housing;

B. a flow chamber in said housing having an inlet opening for receiving air from a conditioned area, an outlet opening for returning air thereto, an exhaust opening for discharging air from said system, and an intake opening for drawing fresh air thereinto;

'C. a return damper in said housing substantially dividing said chamber into two parts, said inlet and exhaust openings communicating with one of said parts and said outlet and intake openings communicating with the other part thereof, direct airflow between said parts being substantially blocked by said damper in the closed position thereof;

D. at least one additional damper in said housing overlying said exhaust and intake openings, airflow therethrough being substantially blocked by said additional damper in the closed position thereof;

E. control means for driving said dampers and operatively coupling them together in such a manner that when one of said dampers is moved from said closed position to the open position thereof the other one of said dampers is moved from the open position to said closed position thereof; and

F. a heat exchanger comprising a heat exchange member overlying each of said exhaust and intake openings and a pump for circulating a heat exchange fluid through said heat exchanger from one of said members to the other, whereby heat is extracted from air passing through one of said exhaust and intake openings and is dissipated to cooler air passing through the other one thereof, when said additional damper is in an open position.

7. The system of claim 6 additionally including: an upstream conduit connected to said inlet opening of said flow chamber for conveying air thereto; a downstream conduit connected to said outlet opening of said flow chamber for conveying air therefrom; a blower in said upstream conduit for inducing airflow toward said unit; and a blower in said downstream conduit for inducing airflow from said unit; said upstream blower being sized and powered to deliver air to said return damper at a kinetic energy level of substantially zero, and said dampers and openings being cooperatively dimensioned and configured for said downstream blower to draw air at substantially ill said control means being automatically responsive to the signal from said generating means to drive said dampers in such a manner as will tend to substantially maintain a desired preselected temperature in air flowing past the same extremity of said downstream conduit.

10. The system of claim 8 additionally including an electrostatic precipitator upstream of said exhaust outlet to ensure that recycled and exhausted portions of the air from the conditioned area contain a reduced concentration of pollutants.

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENTNO. 3,618,659

DATED November 9, 1971 INVENTORiS) Davis I. Rawal It is certified that error appears in the above-identified patent and that said Letters Patent is hereby corrected as shown below:

Column 3, line 40, delete the material begin ing with "In lieu of" through columns 4, 5 and 6 to line 23 ending with the words of pollutants".

Signed and Scaled this Fifteenth Day of May 1984 [SEAL] A nest:

GERALD J. MOSSINGHOFF Arresting Offlccr Commissioner ofl'amm and Trademarks

Claims

2. The method of claim 1 wherein said stale air and said fresh air are at different temperatures, wherein the temperature desired in said mixture is intermediate thereof, and wherein said volume of air discharged and admitted is controlled to provide proportions of fresh and recycle air in said mixture appropriate to attain said desired temperature therein.
3. The method of claim 2 including the additional step of extracting a portion of the heat energy from the warmer of said discharged volume and said admitted volume, and transferring said heat energy to the cooler one thereof.
4. The method of claim 2 additionally including the step of generating a temperature dependent signal responsive to the temperature in said conditioned area for automatic control of said volume of air discharged and admitted.
5. The method of claim 1 including the additional step of cleaning said stale air to remove pollutants therefrom before delivery to said return damper and discharge of said volume thereof.
6. In an environmental conditioning system, a modular damper unit comprising: A. a housing; B. a flow chamber in said housing having an inlet opening for receiving air from a conditioned area, an outlet opening for returning air thereto, an exhaust opening for discharging air from said system, and an intake opening for drawing fresh air thereinto; C. a return damper in said housing substantially dividing said chamber into two parts, said inlet and exhaust openings communicating with one of said parts and said outlet and intake openings communicating with the other part thereof, direct airflow between said parts being substantially blocked by said damper in the closed position thereof; D. at least one additional damper in said housing overlying said exhaust and intake openings, airflow therethrough being substantially blocked by said additional damper in the closed position thereof; E. control means for driving said dampers and operatively coupling them together in such a manner that when one of said dampers is moved from said closed position to the open position thereof the other one of said dampers is moved from the open position to said closed position thereof; and F. a heat exchanger comprising a heat exchange member overlying each of said exhaust and intake openings and a pump for circulating a heat exchange fluid through said heat exchanger from one of said members to the other, whereby heat is extracted from air passing through one of said exhaust and intake openings and is dissipated to cooler air passing through the other one thereof, when said additional damper is in an open position.
7. The system of claim 6 additionally including: an upstream conduit connected to said inlet opening of said flow chamber for conveying air thereto; a downstream conduit connected to said outlet opening of said flow chamber for conveying air therefrom; a blower in said upstream conduit for inducing airflow toward said unit; and a blower in said downstream conduit for inducing airflow from said unit; said upstream blower being sized and powered to deliver air to said return damper at a kinetic energy level of substantially zero, and said dampers and openings being cooperatively dimensioned and configured for said downstream blower to draw air at substantially the same volumetric rate through said return damper when said additional damper is in closed position and through said intake opening when said return damper is in said closed position thereof.
8. The system of claim 7 wherein said blowers are relatively sized and powered to provide substantially the same volumetRic rate of airflow at the outer extremities of said upstream and downstream conduits.
9. The system of claim 8 including a temperature sensor having means for generating a temperature dependent signal, said control means being automatically responsive to the signal from said generating means to drive said dampers in such a manner as will tend to substantially maintain a desired preselected temperature in air flowing past the same extremity of said downstream conduit.
10. The system of claim 8 additionally including an electrostatic precipitator upstream of said exhaust outlet to ensure that recycled and exhausted portions of the air from the conditioned area contain a reduced concentration of pollutants.