US3782448A

US3782448A - Air conditioning structure

Info

Publication number: US3782448A
Application number: US00254686A
Authority: US
Inventors: R Clark
Original assignee: Deutsche ITT Industries GmbH
Current assignee: TDK Micronas GmbH; ITT Inc
Priority date: 1972-05-18
Filing date: 1972-05-18
Publication date: 1974-01-01
Anticipated expiration: 1991-01-01
Also published as: DE2324262A1

Abstract

An air conditioning structure wherein an outside air flow path is vertically positioned above a return air flow path, each flow path including an evaporator structure and an air drive fan. The two paths are separated by a floor to minimize the commingling of the return and outside air and separate air drive fans are provided for each path driven. The return air path includes a hot deck and the outside air path includes a cold deck.

Description

[ Jan. 1,1974

[ AIR CONDITIONING STRUCTURE [75] Inventor: Ralph E. Clark, Abington, Pa.

[73] Assignee: International Telephone and Telegraph Corporation, Nutley, NJ.

[22] Filed: May 18, 1972 [2]] Appl. No.: 254,686

[52] US. Cl. 165/16, 165/127 Downs l65/l6 Kreuttner 165/22 X Primary ExaminerManuel A. Antonakas AttorneyC. Cornell Remsen, Jr. et al.

[ 5 7 ABSTRACT An air conditioning structure wherein an outside air flow path is vertically positioned above a return air 51 1m. (:1 F28f 27/00 flow Path each Path including an evapmm [58] Field of Search 16571 4 16 22 26 Structure and drive The Paths are SePa' 65/27 30 10 12 1 rated by a floor to minimize the commingling Of the return and outside air and separate air drive fans are l 56] References Cited provided for each path driven. The return air path includes a hot deck and the outside air path includes a UNITED STATES PATENTS cold deck. 3,2l7,790 I l/l965 Wasson et a] l65/l6 1,949,735 3 1934 Bulkeley l65/16 4 Claims, 2 Drawing Figures 82 COL D DECK Q 2 I 33 L 1 I I fi o E DECK AIR CONDITIONING STRUCTURE BACKGROUND OF THE INVENTION This invention relates to structures for air conditioning systems and more particularly, to such structures separating return air and outside air.

Air conditioning systems for building containing a plurality of zoneS to be controlled usually utilize structures into which return air from within the building and outside or ventilation air is provided. These structures include evaporator apparatus for cooling the ingested air and hot and cold decks into which selected portions of the cooled air are provided. The cold deck may be no more than a vent path but may include the evaporator apparatus, while the hot deck usually contains a furnace for heating the air transmitted thereto. As is well known in the art, the air from the hot and cold decks is combined in selected ratios at any one of a number of points as desired and the combined air is provided to the zones to be controlled in accordance with their requirements. This type of unit is deficient in that the outside and return air is mixed after it enters the structure and the mixed air is driven by a single fan section, usually consisting of multiple fans on a single shaft, through a single evaporator usually consisting of one or more separate refrigerant circuits, thereby cooling all the air entering the structure to the selected cold deck temperature, conventionally 55F. It will be readily seen by those skilled in the art that where, for example, with most zones calling for moderately warm air, i.e., air of approximately 75F, and one or more zones calling for 55F air, a large percentage of the air passing the evaporator must be routed to the hot deck where it is heated, and this, after it has just been cooled to 55F either by operation of the evaporator or by mixing the return air with cold outside air to provide air at 55F. This known method of cooling is thus wasteful since it is inefficient to cool return air at 75-80F or mix it with cold outside air to provide 55F air and then to heat it or part of it to the temperature required by the various zones to be controlled.

It has been recognized by those skilled in the art that it would be more efficient to pass the return air through the structure without cooling it, thereby allowing it to assist in maintaining the hot deck temperature, and to transmit the outside air separately when the outside air is relatively cool to assist in maintaining the cold deck temperature. It has also been recognized by those skilled in the art that in warm weather when the humidity is high and 50 percent to full cooling capacity is required, it is beneficial to dehumidify all air transmitted to the structure even though some zones do not require sensisble cooling. However, efforts in this regard, as exemplified by the teachings of US. Pat. Nos. 3,324,782, 3,372,870 and 3,407,867, have not been satisfactory, in that there has still been substantial mixing between return and outside air and the air, in crossing paths, does not provide an even distribution of air throughout the plurality of zones which are to be controlled. In addition, the air entering the hot deck of these systems is not dehumidified with mechanical refrigeration and allows humid mixed air to enter the zones not requiring sensible cooling.

SUMMARY OF THE INVENTION Therefore, the main object of this invention is to provide an improved structure for a multizone air conditioning system which is more efficient than the structure presently known in the art.

It is a further object of this invention to provide dehumidification of all air when conditions require operation of mechanical refrigeration at greater than 50 percent of capacity.

It is a further object of this invention to provide such a structure in which return air and outside air are maintained and transmitted separately.

It is yet another object of this invention to provide such a structure in which return air aids in maintaining the temperature of the hot deck.

It is still another object of this invention to provide such a structure in which, during cold weather, outside air aids in maintaining the temperature of the cold deck.

According to the invention there is provided an air conditioning system comprising return air input means, return air flow control means positioned downstream of said return air input means, return air drive means positioned downstream of said return air flow control means, hot deck means positioned downstream of said return air drive means, outside air input means positioned above said return air input means, outside air flow control means positioned downstream of said outside air input means, first evaporator means positioned downstream of said outside air flow control means, outside air drive means positioned downstream of said outside air flow control means, and cold deck means positioned downstream of said first evaporator means.

Further objects and features of this invention will become more apparent by reference to the following description taken in conjunction with the accompanying drawing in which:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates a cross-sectional view of the inventive structure for use with an air conditioning system; and

FIG. 2 illustrates a cross-sectional view of an alternative embodiment of such a structure.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 1, a structure or housing 1 includes return air input 2 which receives air taken from within the building, said air to be treated within said structure and sent back into the building to satisfy requirements therein. This return air passes through return air dampers 3 which may be opened or closed automatically or manually by damper drive means 4 coupled thereto, said dampers being pointed in a downward direction so as to direct said return air away from the upper portions of said structure 1. Return air passing through dampers 3 is transmitted through filter 5 which removes odors and impurities from said air, the now-cleaned air passing through an evaporator circuit 6 which, when energized, is capable of substantially cooling said return air to a desired temperature and dehumidifying said return air. Air drive means is provided by a fan 11 which draws said" return air into the lower portion of structure 1 and passes said air to hot deck 12 which includes reheat coil 13, to be more fully discussed below, and heating apparatus 14 which may be, for example, a gas furnace, an electric furnace, a hot water or steam coil, etc., heated air being transmitted in the direction of arrow 15 through the hot deck 12 which may include multizone mixing dampers or a single duct connection, (not shown) in accordance with temperature requirements of -the structure to be cooled, by methods well known in the art. Positioned directly above return air input 2, as part of structure or housing 1, is outside air input 21, with outside air dampers 22 coupled to and controlled by damper drive 4, filter 23, evaporator 24 and fan 25 being positioned sequentially downstream from outside air input 21 in much the same manner as described with respect to the return air system, the corresponding portions of the outside air system being positioned directly above the return air portions. The outside air passing through evaporator apparatus 24 and through fan 25 into cold deck 31 is usually cooled to a selected temperature, this temperature conventionally being 55F. The cooled air is passed from cold deck 31 to the interior of the building in accordance with requests made by the zones within said building through the cold deck 31 which may include multizone mixing dampers 32 or a single duct connection in the same manner as the above-mentioned hot deck 12.

Turning now to the operation of the subject invention it will be seen that return air from the building at a temperature of approximately 75 to 80F enters the lower half of structure 1, and, depending on the position of dampers 3, is passed into the remainder of structure 1. It is noted that a horizontally extending separator panel 33 extends from input end 34 of structure 1 to the region of

dampers

3 and 22 to increase the separation of return air and outside or ventilation air. Damper drive unit 4, which is controlled by the demands of the cold deck opens or closes dampers 3 to the appropriate position, said dampers 3 being arranged, as illustrated, to direct the flow of said return air in a downward direction to minimize the mixing of the return air and said outside air. Outside air enters input 21 and passes in required quantities through dampers 22 which direct the flow of said outside air upward to minimize the mixing of outside air and return air, said damper drive unit being controlled in a manner well known in the art. The segregated streams of outside air and return air pass through

filters

23 and 5 respectively, and said streams are drawn over

evaporators

24 and 6 respectively, by separate fans and separate drive shafts associated therewith, it being clear from the drawings that the outside air is driven by fan 25 while the return air is being driven by fan 11. If the temperature of the outside air and the temperatures required by zones to be controlled are such that only one stage of cooling is required, i.e., only evaporator 24 is operating, for example, if the temperature of the outside air is 60, the temperature of the return air is 75, and some zones request 80F air, and other zones request 55 air, the system is more efficient than previously known systems and its operation will now be described in greater detail. The 60 air is drawn over evaporator 24 which is operating and this outside air, segregated from the return air, is passed to cold deck 31 at approximately 55F. Additionally, said now-cooled air is dehumidified and a drip pan, not shown, is placed in a conventional manner beneath evaporator 24 to provide for the ejection of said removed water to the exterior of the air conditioning system. The return air at 75 is drawn over evaporator 6 by fan 11 and since as stated above said evaporator 6 is not operating, the return air at 75 is transmitted to hot deck l2 where it is raised to the re quired temperature of 80, by either the operation of furnace 14 or the operation of reheat coil 13, said reheat coil utilizing the heat absorbed by the refrigerant in evaporator 24 which was utilized in cooling the return air from 60 to 55. This efficient use of the heat given up by the outside air in heating the. return air rather than the wasting of the heat given up by the outside air will not be explained in detail since an example of a system which may be utilized for this purpose is more fully described in U.S. Pat. No. 3,631,686 entitled Multizone Air Conditioning System with Reheat, and assigned to the assignee of the present invention.

As will now be clear to those skilled in the art, the instant method of controlling the distribution of return and outside air is substantially more efficient than the method known in the art which usually comprises a single evaporator coil and a single fan assembly which would, in this case, have required the cooling not only of the outside air from 60 to 55, but also the cooling of the return air at to a temperature of 55 and the subsequent reheating of a portion of said now'cooled combined air to a temperature of Thus, there has been a substantial saving of the energy required to heat the return air since it was received at the hot deck at a temperature of 75, requiring only sufficient energy to heat said air an additional 5 and, further, there was a saving of energy, in that only a portion of the total mixed air, that portion comprising the outside air, had to be cooled and that portion by only an increment of 5 rather than as is usual, cooling the total volume of air to 55.

Although the operation of the system as described above describes a situation where all the outside air passed through the upper half of said structure 1 whereas all the return air passed through the lower portion thereof, it will be clear that circumstances exist where essentially all return air is used and other conditions where essentially all outside air is used, and after the appropriate heating and/0r cooling of the separated air streams is accomplished, it is necessary to transmit portions of the air transmitted by fan 25 to the hot deck or portions of the air transmitted from fan 11 to the cold deck. This is accomplished by the proper positioning of hot deck dampers 20 and cold deck dampers 32, it being clear that a closure of dampers or connecting ducts in the cold deck would urge all the air transmitted by

fans

11 and 25 to the hot deck while the cloure of dampers or connecting ducts in the hot deck would urge all the air transmitted by said fans to the cold deck. The operation and control of the hot and cold deck dampers will not be discussed in detail as this method of directing air is well known in the art and it is not critical to the operating efficiency of the subject improved system.

Referring now to FIG. 2, there is illustrated an alternative embodiment of the instant air conditioning structure in which like components bear the same numbers as in H0. 1. The structure of FIG. 2 is similar to that of FIG. 1, the only difference being that

evaporator units

6 and 24 are now positioned between cold deck 31 and air drive means 25 rather than between the air drive means and the filters, as is illustrated in FIG. 1. The structure illustrated in FlG. 2 has been found to have both advantages and disadvantages relative to the structure illustrated in FIG. 1. For example, if it is determined that 60 percent of the total cooling capacity of the structure is required, then clearly the structure illustrated in FIG. 2 is more efficient than "that illustrated in FIG. 1. This is due to the fact that when 60 percent of the toal cooling capcity is required both evaporator units will be operating and if the structure illustrated in FIG. 1 is utilized all of the air entering the structure, both the outside air and the return air will be cooled with the resulting requirement that much of the return air will have to be heated in the hot deck after it has just been cooled. On the other hand, utilizing the structure illustrated in FIG. 2 allows the transmission of return air through input 2 to be transmitted directly to hot deck 12 without any cooling and only the air transmitted to cold deck 31 will be cooled. It will be seen, however, that with the foregoing circumstances existing, the structure of FIG. 2 is not as satisfactory as the structure illustrated in FIG. 1 due to the fact that the aforementioned return air, which is transmitted directly to the hot deck without cooling, will not be dehumidifed and, thus, warm air containing a great deal of moisture will be transmitted into the controlled environment, which is, of course, undesirable. It is thus seen that although both embodiments of the invention provide improved performance relative to those structures known in the art, due to the separation of outside and return air, nevertheless the two illustrated structures provide advantages and disadvantages relative to each other and it is the responsibility of the user to determine which best meets the needs of the environment to be controlled.

While the principles of the invention have been described in connection with specific structures it is to be clearly understood that this description is made only by way of example and not as a limitation to the scope of my invention as set forth in the objects thereof and in the accompanying claims.

I claim:

1. An air conditioning system comprising:

return air input means;

return air flow control means positioned downstream of said return air input means;

return air drive means positioned downstream of said return air flow control means;

hot deck means positioned downstream of said return air drive means;

outside air input means positioned above said return air input means;

outside air flow control means positioned downstream of said outside air input means;

said outside air flow control means and said return air flow control means each including a set of dampers, each said damper set positioned to direct air flowing therethrough away from said other, said dampers being reciprocally controlled so that as one opens one closes thereby providing a constant total volume of said return air and said outside air entering said air conditioning system;

first evaporator means positioned downstream of said air flow control means;

second evaporator means positioned downstream of said return air flow control means, said first and said second evaporator means cooling said outside air and said return air, respectively, and said first evaporator means being controlled to operate alone when less than a predetermined degree of cooling capacity is required;

separator means extending from said air input means toward said first and second evaporator means positioned to separate said return air and said outside air;

outside air drive means positioned downstream of said outside air flow control means; and

cold deck means positioned downstream of said first evaporator means.

2. An air conditioning system, according to claim 1, wherein said return air drive means is positioned downstream from said first evaporator means.

3. An air conditioning system, according to claim 2, wherein said hot deck means is positioned downstream from said return air drive means.

4. An air conditioning system, according to claim 1, wherein said outside air drive means is positioned downstream from said first evaporator means.

Claims

1. An air conditioning system comprising: return air input means; return air flow control means positioned downstream of said return air input means; return air drive means positioned downstream of said return air flow control means; hot deck means positioned downstream of said return air drive means; outside air input means positioned above said return air input means; outside air flow control means positioned downstream of said outside air input means; said outside air flow control means and said return air flow control means each including a set of dampers, each said damper set positioned to direct air flowing therethrough away from said other, said dampers being reciprocally controlled so that as one opens one closes thereby providing a constant total volume of said return air and said outside air entering said air conditioning system; first evaporator means positioned downstream of said air flow control means; second evaporator means positioned downstream of said return air flow control means, said first and said second evaporator means cooling said outside air and said return air, respectively, and said first evaporator means being controlled to operate alone when less than a predetermined degree of cooling capacity is required; separator means extending from said air input means toward said first and second evaporator means positioned to separate said return air and said outside air; outside air drive means positioned downstream of said outside air flow control means; and cold deck means positioned downstream of said first evaporator means.