Abstract:
The present invention relates to an improved air conditioning filter and cooling/heating coil that can easily be applied to new and existing air handling systems. The slant design of these components allows a more efficient heat transfer and particle entrapment than their conventional counterparts. By residing at an angle in their air handling enclosures, and by virtue of their oblique prismatic construction, more filter media can be used and more heat transfer surface area can be incorporated without offering any substantial additional impediments to the flow of air. At angles of 45 degrees air friction of the coil and filter are reduced by 40 to 55 percent.

Description:
FIELD OF THE INVENTION 
   The present invention relates to improved apparatus for the conditioning of air. More specifically, it relates to a new design for an air filter and the coils (heat exchanger) to be used in an air handling system that maximizes the spacial constraints of the air handling containment system with filter and coil having a more geometrically efficient design. This design allows for a much higher efficiency in the air filtration capacity and the thermal conductivity of the coil. 
   BACKGROUND 
   Governmentally imposed regulations force higher efficiency standards on all commercial electro-mechanical devices in an attempt to reduce the ever increasing electrical needs of our society. Air handling systems, being one of the larger electrical energy users in commercial buildings, have recently come under stringent future regulations. Current regulations to be met by the year 2010 will force a large increase in efficiency. 
   Existing coils and air filters have a rectangular axial cross section and reside normally in their enclosures (air handling units). Their three dimension configuration is that of a cuboid or, stated otherwise, a right prism having only rectangular faces. Any increase in efficiency is achieved by using multiples of these units or by staggering configurations of smaller filters and coils. Overall efficiency improvements are becoming increasingly difficult. 
   This invention utilizes a slant design of these components that allows a more efficient heat transfer and particle entrapment than their conventional counterparts. By residing at an angle in their air handling enclosures, and by virtue of their oblique prismatic construction, more tubes can be used, more plate thermal conductive surface area can incorporated onto the coil, a larger coil face area can be realized, and more filter media can be used in the filter. When residing in the air handling unit at angles of 45 degrees, there is approximately a 41% increase in coil heat transfer area and particulate entrapment area. More importantly, the face velocity and resultant air friction of the passing air decreases significantly, thereby reducing the amount of work the prime mover has to do. 
   This slant design requires more linear space than single, normally situated conventional elements do, but offers considerably less restriction to air flow than do multiple normally situated conventional elements. Thus, a significant increase in efficiency can be realized with a minimum increase in spacial utilization and a significant reduction in air restriction. 
   Such conditioning air apparatus innovations as the present invention provides, overcome the pitfalls of the prior art and are a cost effective, simple solution that enable a considerable jump in efficiency while allowing a spatially effective air handling unit design. 
   SUMMARY OF THE INVENTION 
   The general purpose of the present invention, which will be described subsequently in greater detail, is to provide an economical, energy efficient, simple coil and filter that will be easily applied into the spatial constraints of existing commercial air handling systems. 
   It has many of the advantages mentioned heretofore and many novel features that result in new, high efficiency conditioning air components which are not anticipated, rendered obvious, suggested, or even implied by any of the prior art, either alone or in any combination thereof. 
   In accordance with the invention, an object of the present invention is to provide an improved air filter and heat exchanger coil that will reduce air friction compared to a conventional design. 
   It is another object of this invention to provide improved an air filter and cooling/heating coil that increases heat transfer and particulate filtration while reducing air resistance. 
   It is a further object of this invention to provide an improved air filter and cooling/heating coil that is simple and economical to construct. 
   It is a final object of the present invention to provide and improved air filter and heat exchanger coil design that will reduce the height and resultant casing cost of air handling units. 
   The subject matter of the present invention is particularly pointed out and distinctly claimed in the concluding portion of this specification. However, both the organization and method of operation, together with further advantages and objects thereof, may best be understood by reference to the following description taken in connection with accompanying drawings wherein like reference characters refer to like elements. Other objects, features and aspects of the present invention are discussed in greater detail below. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of the slant air conditioning coil and slant filter arrangement installed in an air handling enclosure; 
       FIG. 2  is a top cross sectional view of a conventional air conditioning coil; 
       FIG. 3  is a side view of a conventional air conditioning coil and filter arrangement installed in an air handling enclosure; 
       FIG. 4  is a perspective view of an angled conventional air conditioning coil and filter arrangement installed in an air handling enclosure; 
       FIG. 5  is a side view of an angled conventional embodiment air conditioning coil and filter arrangement installed in an air handling enclosure; 
       FIG. 6  is a side view of a slant air conditioning coil and slant filter arrangement installed in an air handling enclosure; 
       FIG. 7  is a side view of a conventional air conditioning coil; 
       FIG. 8  is a side view of a slant air conditioning coil; 
       FIG. 9  is a side view of two angled conventional air conditioning coils coupled to form an “A Coil”; 
       FIG. 10  is a perspective view of a slant “A Coil” installed in an air handling enclosure; and 
       FIG. 11  is comparative view of the linear spatial arrangement of a conventional air conditioning coil and a staggered slant coil and slant filter arrangement. 
   

   DETAILED DESCRIPTION 
   The present invention relates to a high efficiency coil and filer for an air handling system, utilizing a slant design that can be easily applied to new air handling systems and capable of offering significant increases in efficiency. 
   There has thus been outlined, rather broadly, the more important features of the invention in order that the detailed description thereof that follows may be better understood and in order that the present contribution to the art may be better appreciated. There are, of course, additional features of the invention that will be described hereinafter and which will form the subject matter of the claims appended hereto. 
   In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. 
   The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of descriptions and should not be regarded as limiting. As such, those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention. 
   The components and operation of a standard cooling/heating coil and filter as used in an air conditioning system are well known in the industry. It is the unique geometric configuration and design of these that are the subject of this invention. 
   Looking at  FIG. 1 , the slant air conditioning coil  2  and slant filter  4  arrangement can be seen installed in an air handling unit  6 . Referring to  FIG. 2  the general arrangement of an air conditioning coil can be seen. Other than the geometric configuration differences between a conventional coil  20  and a slant coil  2 , both coils have the same elements. The coils are of a generally planar shape that have rows of substantially similar bent tubes  8  held in a substantially equally spaced, parallel arrangement from adjacent tubes by a plethora of congruent, thin pleated (or flat) fins  10 , through which the tubes  8 , pass normally. All tubes are connected at one end to an inlet header  12  and at the other, distal end, to an outlet header  14 . The fins  10  reside substantially parallel to adjacent fins  10 . Fins  10  are shown in a pleated configuration, although they may be in a truly flat planar configuration as well. The tubes  8 , fins  10 , inlet header  12  and outlet header  14  are held in their spatial arrangement by support frames  16 , side support plates  18  and top/bottom support plates  19  ( FIG. 4 ). These support frames  16 , side support plates  18  and top/bottom support plates  19  form a support structure. For clarification purposes throughout, all coils are illustrated from the side that does not have the inlet header  12  and outlet header  14  affixed thereon. 
   It is well known in the industry that support structures vary, however the conventional overall geometric shape of a coil is cuboid. The overall geometric shapes of the slant coil  2  and slant filter  4  are parallelepiped as seen in  FIG. 1 , for example, or more particularly are that of oblique prisms having three pair of congruent (and thus parallel) sides, two pair of which form rectangles and one pair which forms a non-rectangular parallelogram. This is best illustrated in  FIG. 1 . (Stated otherwise, the coil and filter have axial cross sections in the geometric shape of a parallelogram possessing both acute and obtuse interior angles.) 
   The slant filter  4  and conventional filter  22  are illustrated as generic pleated filter designs. The actual filter media can be selected from a plethora of available air filtration media including but not limited to fiberglass and pleated cotton. 
   Looking at  FIG. 3 , the conventional industry standard for placement of conventional air conditioning coils  20  and conventional filers  22  is illustrated. It can be seen that both conventional coil  20  and conventional filter  22  have a cuboid geometry. Generally, conventional coil  20  and conventional filter  22  reside perpendicular to the direction of air flow  25 . In this manner, the plane of each tube  8  is parallel to the direction of air flow  24 . 
   When additional cooling is required larger conventional coils  20  and larger conventional filters  22  are placed on an angle into the air handling unit  6 . This is illustrated in perspective in  FIG. 4  and in side view in  FIG. 5 . While this angling does offer an increased surface area, it is less efficient as will be evident when discussed later, herein. This angled placement results in voids  24  that can be seen between the top/bottom support plates  19  and the air handling unit  6 . A similar situation exists about the conventional filter  22  and air handling unit  6  wherein voids  24  are also created. 
   Looking at the slant coil  2  and slant filter  4  in  FIG. 6 , it can be seen that both of their cross sections form parallelograms rather than rectangles. In this manner there are no voids and less air turbulence. The importance of this is that coil  2  has more face area  11  which decreases the face velocity and air resistance, and fins  10  have more surface area with which to transfer heat, increasing efficiency. 
     FIGS. 7 and 8  show side by side comparisons of a slant coil  2  and a conventional coil  20 . It can be seen that the air handling unit height of the conventional coil  20  (denoted as line A in  FIG. 7 ) is the same as the effective face height for this coil. In the slant coil  2  the effective face height (denoted as line C in  FIG. 8 ) is greater than the air handling unit height (denoted as line B in  FIG. 8 ) by the air handling unit height/cosine of the angle of inclination. The inclination of the slant coil  2  in the air handling unit  6 , changes the face area  11  of the coil  2  as depicted in the following chart. 
   
     
       
             
           
             
             
             
           
         
             
                 
             
             
               Coil Angle vs Change in Coil Face Area 
             
           
        
         
             
               Angle of Coil (from 
               Coil Face Area 
               Increase from 
             
             
               air flow direction) 
               (linear units 2 ) 
               Conventional 
             
             
                 
             
             
               90 
               100 
               N/A 
             
             
               60 
               121 
               21% 
             
             
               45 
               141 
               41% 
             
             
               30 
               200 
               100% 
             
             
                 
             
           
        
       
     
   
   Looking at  FIGS. 5 and 6  the differences between the configuration of the tubes  8  between the conventional coil  20  and the slat coil  2  can best be seen. The tubes  8  in both coils lie in substantially similar, parallel tube columns  13  with identical spacing between the tubes  8  in each column  13 . In  FIGS. 5 and 6  each coil only has three tube columns  13  that are oriented vertically, but it is well known in the art that the position and number of tube columns is adjusted to fit the specific requirements of the situation. The tube columns are arranged such that the tubes in adjacent tube columns  13  form tube rows  9  that each reside in a common plane. 
   In the conventional coil  20  the plane of tube rows  9  lies normal to the plane of the tube columns  13  and the coil face  15 . In the slant coil  2  the plane of tube rows  9  resides at an angle to the plane of the tube columns  13  and the coil face  15 . This angle in the slant coil is the same angle as that formed between the top/bottom support plates  19  and the side support plates  18 , which is also the same angle formed between the coil face  15  and the air handling unit. In this way, when the slant coil  2  resides in the air handling unit  6  the plane of the tube rows resides parallel to the flow of air in the air handling unit  6 . By ensuring that these planes of tube rows reside parallel to both the linear axis of the flow handling unit  6  and the flow of air in the air handling unit  25 , turbulence, friction and back pressure are minimized as discussed in detail herein. In contrast, when the conventional coil  20  is placed in the air handling unit  6  so as to reside at an angle, the plane of the tube rows resides at an angle with respect to the flow of air in the air handling unit  6 , decreasing efficiency and increasing friction, turbulence and back pressure. 
     FIG. 9  depicts the normal configuration of an “A coil”  26 . The industry standard is to angle two conventional coils  20  toward each other to form a coil in the shape of the letter A. This formation results in under utilized space  28 . Using a combination of two slant coils  2  to form a slant A coil  30 , ( FIG. 10 ) the advantages of increased heat transfer surface, lower air resistance, and reduced air turbulence, results in a higher overall efficiency. 
     FIG. 11  shows a comparison between a staggered slant coil  32  and staggered slant filter  34  combination, and that of a conventional coil  20  and a Vee filter  36  arrangement. The air handling unit length used to house this staggered slant combination is shorter than that required to house a slant coil  2  and slant filter  4  and rivals that of the abovementioned conventional arrangement. Basically, two shortened, slant coils are offset into a vertically staggered configuration and held in this configuration by a common support member  38 . It can be seen that the air handling unit length L 2  of the staggered configuration approaches the air handling unit length L 1  of a conventional coil  20  and filter. The benefit of the staggered slat coil  32  design is that it provides more coil face area  11  than a conventional coil  20  yet utilizes the same height and similar length requirements as does a conventional coil  20  in an air handling unit. The same can be said about the staggered slant filter  34  design. 
   The advantages of the present invention in operation, are best explained in the following section. To achieve an increase in heat transfer efficiency and particulate filtration effectiveness and holding capacity, the passing air must encounter more coil (more fin surface area, more coil face area  11  and number of tubes  8 ) and more filter media surface area. If the media and coil reside normal to the passing air, then the resistance to air flow must rise since there is more coil and filter media to traverse through or across, than initially. This will necessitate larger, energy consuming air drivers (fans). Any gains in heat transfer and filtration must then be offset against the heat input of the larger fans and additional energy losses. However, this can be accomplished with the angled units or slant design while also lowering the coil face velocity and air resistance. 
   In transferring heat with a coil, the heat transfer area of the coil must remain in contact with the passing air for as long as possible and the fins that transfer the heat by virtue of their surface area size must be maximized. The efficiency of the filtration is a function of the amount of filter media that the air passes through. Angling these elements at 45 degrees offers a 41% increase in face area. The effective face area of a slant coil  2  and or slant filter  4  can be adjusted by selecting a greater angle that they sit in the air handling unit  6 . As the angle is decreased below that of the 90 degree, vertical position that their conventional counterparts reside in, their efficiency rises. Unfortunately, as the angle is reduced as above, the amount of length in the direction of air flow that the slant coil  2  and slant filter  4  occupy also rises. Thus, the slant angle used on the invention described herein may be dictated by either the efficiency desired or the air handling unit&#39;s spatial constraints. 
   Experimentation was performed with a first conventional coil placed at 90 degrees in an air handling unit, a second conventional coil placed at 45 degrees in the same air handling unit and a slant coil placed at 45 degrees in the same air handling unit. The face areas of the first conventional coil, second conventional coil and slant coil were respectively 10.42 ft 2 , 12.08 ft 2  and 14.17 ft 2 . The coils ran chilled water at a standard fluid flow rate of 31.30 gpm at an entering fluid temperature of 44.00 degrees Fahrenheit. The air flow was 5000 cfm. Their respective face velocities were 480 ft 3 /min, 414 ft 3 /min and 353 ft 3 /min. The percentage decrease in air pressure drop for the second conventional coil and slant coil (with respect to the air pressure drop of the first conventional coil), were 24.3 percent and 42.8 percent. This results in a substantial savings in fan energy. 
   Experimentation has shown that with all parameters held substantially similar, a slant filter positioned at 45 degrees in an air handling unit vs a conventional filter positioned vertically (at 90 degrees), will result in 15 percent lowering of the fan static pressure giving a 27.7 percent savings in fan energy. 
   The above description will enable any person skilled in the art to make and use this invention. It also sets forth the best modes for carrying out this invention. There are numerous variations and modifications thereof that will also remain readily apparent to others skilled in the art, now that the general principles of the present invention have been disclosed.