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Publication numberUS20020174671 A1
Publication typeApplication
Application numberUS 09/863,542
Publication dateNov 28, 2002
Filing dateMay 22, 2001
Priority dateMay 22, 2001
Publication number09863542, 863542, US 2002/0174671 A1, US 2002/174671 A1, US 20020174671 A1, US 20020174671A1, US 2002174671 A1, US 2002174671A1, US-A1-20020174671, US-A1-2002174671, US2002/0174671A1, US2002/174671A1, US20020174671 A1, US20020174671A1, US2002174671 A1, US2002174671A1
InventorsKen Wilkinson
Original AssigneeKen Wilkinson
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Solar radiation screen for air conditioner condenser
US 20020174671 A1
Abstract
A solar radiation screen for an air conditioner condenser includes a support body defining an inward side configured to be placed proximate to the air conditioner condenser, and an outward side configured to be placed proximate to a source of air to be passed through the air conditioner condenser. A plurality of solar blocking surfaces are supported by the body, the solar blocking surfaces being downward sloping from a point proximate the inward side of the support body to a point proximate the outward side of the body. The solar blocking surfaces are spaced apart from one another to the allow the source of air to essentially pass freely over the solar blocking surfaces and through the condenser. The solar blocking surfaces can be downward sloping at an predetermined angle selected to prevent direct solar radiation from passing between the solar blocking surfaces and to the condenser.
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Claims(20)
What is claimed is:
1. A solar radiation screen for an air conditioner condenser, comprising:
a support body defining an inward side configured to be placed proximate to the air conditioner condenser, and an outward side configured to be placed proximate to a source of air to be passed through the air conditioner condenser;
a plurality of solar blocking surfaces supported by the body, the solar blocking surfaces being downward sloping from a point proximate the inward side of the support body to a point proximate the outward side of the body, the solar blocking surfaces being spaced apart from one another to the allow the source of air to essentially pass freely over the solar blocking surfaces and through the condenser.
2. The solar radiation screen of claim 1, and wherein the support body comprises opposing side members which span between the inward side and the outward side of the support body, and the solar blocking surfaces are defined by ends, and further wherein the side members support the solar blocking surfaces at their ends.
3. The solar radiation screen of claim 2, and further comprising at least one vertical support member disposed between the side members of the support body, and wherein the vertical support member further supports the solar blocking surfaces.
4. The solar radiation screen of claim 2, and wherein the solar blocking surfaces are pivotally supported at their ends by the side members.
5. The solar radiation screen of claim 1, and wherein the solar blocking surface is defined by an upper surface upon which solar radiation can directly impinge when the screen is in use, and an opposite lower surface, and wherein the lower surface of the solar blocking surface is a light diffusing surface.
6. The solar radiation screen of claim 1, and wherein the solar blocking surface is defined by an upper surface upon which solar radiation can directly impinge when the screen is in use, and an opposite lower surface, and wherein the upper surface of the solar blocking surface is a light diffusing surface.
7. The solar radiation screen of claim 1, and wherein the solar blocking surfaces are downward sloping at an predetermined angle selected to prevent direct solar radiation from passing between the solar blocking surfaces and to the condenser.
8. A solar radiation screen for an air conditioner condenser, comprising a sheet of material having an inward side configured to be placed proximate to the air conditioner condenser, and an outward side configured to be placed proximate to a source of air to be passed through the air conditioner condenser, the sheet of material defining a plurality of openings through which the source of air can pass to the condenser, the openings being overhung by solar blocking surfaces formed from the sheet of material, and sloping downward from a point proximate the outward side of the sheet of material to a point distal from the outward side of the sheet of material.
9. The solar radiation screen of claim 8, and wherein the sheet of material is fabricated from a material selecting from the group consisting of metal or plastic.
10. The solar radiation screen of claim 8, and wherein at least part of the condenser is defined by an outer shape, and further wherein the sheet of material is contoured to conform to the outer shape of the condenser.
11. A solar radiation screen for an air conditioner condenser, comprising:
a plurality of hingedly connected adjacent solar screen panels, each said panel comprising:
a support body defining an inward side configured to be placed proximate to the air conditioner condenser, and an outward side configured to be placed proximate to a source of air to be passed through the air conditioner condenser; and
a plurality of solar blocking surfaces supported by the body, the solar blocking surfaces being downward sloping away from the condenser when the panel is located proximate the condenser, the solar blocking surfaces being spaced apart from one another to the allow the source of air to pass over the solar blocking surfaces and through the condenser.
12. The solar radiation screen of claim 11, and wherein the solar blocking surfaces are downward sloping at an predetermined angle selected to prevent direct solar radiation from passing between the solar blocking surfaces and to the condenser.
13. The solar radiation screen of claim 11, and wherein the solar blocking surfaces are downward sloping at an predetermined angle selected to reflect solar radiation directly impinging on the solar blocking surface away from the condenser.
14. The solar radiation screen of claim 11, and wherein the solar blocking surfaces are defined by a horizontal length and a width perpendicular to the horizontal length, and wherein the width is selected to prevent direct solar radiation from passing between the solar blocking surfaces and to the condenser.
15. The solar radiation screen of claim 11, and wherein the solar screen panels are hingedly connected by a flexible joint.
16. A solar radiation screen for an air conditioner condenser, comprising a sheet of material defining a total area and having an inward side configured to be placed proximate to the air conditioner condenser, and an outward side configured to be placed proximate to a source of air to be passed through the air conditioner condenser, the sheet of material defining a plurality of openings through which the source of air can pass to the condenser, the openings collectively defining an opening area, and wherein the opening area is less than half of the total area.
17. The solar radiation screen of claim 16, and wherein the opening area is less than one third of the total area.
18. The solar radiation screen of claim 16, and wherein the outward side of the sheet of material is a surface configured to reflect a majority of direct solar radiation impinging on the outward side of the sheet of material.
19. A solar radiation screen for an air conditioner condenser, comprising a body supporting a plurality of solar blocking surfaces, the solar blocking surfaces configured to block from the condenser at least about fifty percent of direct solar radiation which is anticipated as impinging on the solar radiation screen.
20. The solar radiation screen of claim 19, and wherein the plurality of solar blocking surfaces are positioned on the body in a position to account for anticipated directions at which solar radiation will directly impinge on the solar radiation screen when in use.
Description
FIELD OF THE INVENTION

[0001] The invention claimed and disclosed herein pertains to air conditioners, and in particular to methods and apparatus to improve the performance of a condenser in an air conditioner.

BACKGROUND OF THE INVENTION

[0002] The typical configuration for an air conditioning system used to cool an indoor environmental space is a closed fluid loop which circulates a refrigerant through a compressor, a condenser, a thermal expansion valve, a condenser, an evaporator, and then back to the compressor. FIG. 1A depicts a schematic diagram of a basic prior art air conditioning system. The refrigerant exits the compressor 2 as a vapor, and is liquified in the condenser 4. As the liquid refrigerant vaporizes at the thermal expansion valve 6, the temperature drops, allowing the refrigerant to absorb heat QB from the indoor environment via the evaporator 8. The evaporator is typically located in the indoor environment, and air from the indoor environment is passed over a series of tubing coils which conduct the refrigerant through the evaporator. As the indoor air is passed over the coils, heat QB is transferred from the indoor air to the refrigerant. The refrigerant is then conveyed to the condenser 4 (via the compressor) where the heat from the indoor air QB is expelled to another environment. A typical configuration is to pass the refrigerant through a series of tubing coils in the condenser 4 while passing air from an outdoor environment over the coils. Heat is thus removed from the refrigerant, causing it to condense to a liquid. The liquid refrigerant is then passed back to the evaporator to extract more heat from the air in the indoor environmental space. It is thus desirable to remove as much heat as possible from the refrigerant in the condenser so that the refrigerant has more thermal capacity to absorb heat from the indoor environment. It is also desirable to prevent extraneous heat from entering the condenser, which reduces the condenser's ability to transfer the heat from the building QB to the outdoor environment.

[0003] What is needed then is an air conditioner which achieves the benefits to be derived from similar prior art devices, but which avoids the shortcomings and detriments individually associated therewith.

SUMMARY OF THE INVENTION

[0004] The present invention provides for a solar radiation screen to block a majority of direct solar radiation which can impinge on an air conditioner condenser. Preferably, the solar screen is configured to block the majority of direct solar radiation which can impinge on the air conditioner condenser during selected times of the day, and during selected seasons of the year. The screen is also preferably configured to allow relatively free flow of air through the solar screen and to the condenser so that performance of the condenser is not adversely affected by the presence of the solar radiation screen.

[0005] A first embodiment of the present invention provides for a solar radiation screen for an air conditioner condenser which includes a support body defining an inward side configured to be placed proximate to the air conditioner condenser, and an outward side configured to be placed proximate to a source of air to be passed through the air conditioner condenser. A plurality of solar blocking surfaces are supported by the body, the solar blocking surfaces being downward sloping from a point proximate the inward side of the support body to a point proximate the outward side of the body. The solar blocking surfaces are spaced apart from one another to the allow the source of air to essentially pass freely over the solar blocking surfaces and through the condenser. The solar blocking surfaces are preferably downward sloping at an predetermined angle selected to prevent direct solar radiation from passing between the solar blocking surfaces and to the condenser.

[0006] A second embodiment of the present invention provides for a solar radiation screen for an air conditioner condenser, comprising a sheet of material having an inward side configured to be placed proximate to the air conditioner condenser, and an outward side configured to be placed proximate to a source of air to be passed through the air conditioner condenser. The sheet of material defines a plurality of openings through which the source of air can pass to the condenser. The openings are overhung by solar blocking surfaces formed from the sheet of material, and the solar blocking surfaces slope downward from a point proximate the outward side of the sheet of material to a point distal from the outward side of the sheet of material. The sheet of material can be fabricated from metal or plastic, and preferably can be formed to approximately contour to the outer surface of the condenser.

[0007] A third embodiment of the present invention provides for a solar radiation screen for an air conditioner condenser, having a plurality of hingedly connected adjacent solar screen panels. Each panel includes a support body defining an inward side configured to be placed proximate to the air conditioner condenser, and an outward side configured to be placed proximate to a source of air to be passed through the air conditioner condenser. Each panel of the solar screen also includes a plurality of solar blocking surfaces supported by the body, the solar blocking surfaces being downward sloping away from the condenser when the panel is located proximate the condenser. The solar blocking surfaces are preferably spaced apart from one another to the allow the source of air to pass over the solar blocking surfaces and through the condenser. Preferably, the solar blocking surfaces are downward sloping at an predetermined angle selected to prevent direct solar radiation from passing between the solar blocking surfaces and to the condenser. Further, the solar blocking surfaces can be downward sloping at an predetermined angle selected to reflect solar radiation directly impinging on the solar blocking surface away from the condenser. The solar blocking surfaces can be defined by a horizontal length and a width perpendicular to the horizontal length. Preferably, the width is selected to prevent direct solar radiation from passing between the solar blocking surfaces and to the condenser.

[0008] In a fourth embodiment of the present invention, a solar radiation screen for an air conditioner condenser comprises a sheet of material defining a total area and having an inward side configured to be placed proximate to the air conditioner condenser, and an outward side configured to be placed proximate to a source of air to be passed through the air conditioner condenser. The sheet of material defines a plurality of openings through which the source of air can pass to the condenser. The openings collectively define an opening area which is preferably less than half of the total area, and more preferably less than one third of the open area. The outward side of the sheet of material can be a surface configured to reflect a majority of direct solar radiation impinging on the outward side of the sheet of material.

[0009] These and other aspects and embodiments of the present invention will now be described in detail with reference to the accompanying drawings, wherein:

DESCRIPTION OF THE DRAWINGS

[0010]FIG. 1A is a simplified schematic diagram of a prior art air conditioning system.

[0011]FIG. 1 is an oblique diagram of a prior art installation of an air conditioning system on the roof of a building.

[0012]FIG. 2 is a schematic diagram depicting a partial side view of a prior art air conditioner condenser exposed to the sun at different times of the day.

[0013]FIG. 3 is a schematic diagram depicting a plan view of a prior art air conditioner condenser exposed to the sun at different times of the day.

[0014]FIG. 4 is an oblique diagram of an installation of an air conditioning condenser on the roof of a building incorporating a solar screen in accordance with one embodiment of the present invention.

[0015]FIG. 5 is a partial side sectional view of the air conditioning condenser incorporating the solar screen depicted in FIG. 4.

[0016]FIG. 6 is a schematic diagram depicting a partial side view of the solar screen of FIG. 5, showing the geometry of the solar blocking surfaces of the solar screen.

[0017]FIG. 7 is a plan view of an air conditioning condenser incorporating a solar screen in accordance with second embodiment of the present invention.

[0018]FIG. 8 is an isometric diagram depicting a detail of two of the solar screen panels depicted in FIG. 7.

[0019]FIG. 9 is another partial side sectional view of the air conditioning condenser incorporating the solar screen depicted in FIG. 4.

[0020]FIG. 10 is an isometric diagram of a solar screen for an air conditioning condenser in accordance with a third embodiment of the present invention.

[0021]FIG. 11 is a side sectional view of the solar screen for an air conditioning condenser depicted in FIG. 10.

[0022]FIG. 12 is a schematic diagram depicting a partial side view of the solar screen of FIG. 5, showing how solar radiation can be reflected by the screen.

[0023]FIG. 13 is a schematic diagram similar to FIG. 12 showing how the angle at which solar blocking surfaces in the solar screen are mounted can affect the reflection of solar radiation by the screen.

[0024]FIG. 14 is a schematic diagram similar to FIG. 13 showing how the angle at which solar blocking surfaces in the solar screen are mounted can affect the reflection of solar radiation by the screen.

[0025]FIG. 15 is a side elevation view of a solar blocking surface in a solar screen of the present invention configured to reflect solar radiation from the bottom surface of the solar blocking surface.

[0026]FIG. 16 is an isometric view of a solar radiation blocking screen in accordance with a fourth embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0027] In many commercial settings (office buildings, for example) the condenser of an air conditioner is located on the roof of a building that the air conditioner is servicing. This is advantageous since liquid refrigerant exiting the condenser can then flow under the force of gravity downward to the condenser, located in the building, where the refrigerant is then used to cool the air in the building. Turning to FIG. 1, a prior art air conditioning configuration is depicted in an oblique view. A building “B”, which can be a multi-story office building, for example, is provided with an air conditioning system. The air conditioning system includes a condenser 10 which is located on the roof “R” of the building “B”. (The other components of the air conditioning system—the compressor, the evaporator, and the thermal expansion valve—are located inside of the building, and are not shown.) Outdoor air “A” is drawn into the condenser using a fan 12, and is exhausted from the fan as exhaust “E”.

[0028] As the outdoor air “A” moves through the condenser 10, the air passes over heat transfer plates 14. The heat transfer plates 14 are in heat transfer communication with tubes (not shown) in the condenser which convey the refrigerant. The heat transfer plates 14 improve the performance of the condenser by providing a larger surface area over which the heat transfer process can occur. Frequently, such plates are made from a conductive metal, such as aluminum, and are quite thin (5-20 mils, for example). The heat transfer plates are also typically spaced quite close together (approximately 10-20 plates per inch). Since the condenser is located on the roof “R” of the building “B”, it is frequently exposed to solar radiation “RS” from the sun. Depending on the time of the year, the hour of the day, and the cloud conditions, more or less solar radiation can impinge on the heat transfer plates 14 of the condenser 10. In many conditions the solar radiation RS causes an increase in the temperature of the heat transfer plates 14, which in turn reduces the efficiency of the condenser. That is, because the temperature differential between the outdoor air “A” and the heat transfer plates 14 is increased as a result of the solar radiation RS, less thermal energy can be removed from the heat transfer plates 14 by the outdoor air “A”. The result is that, in order to maintain the temperature in the building “B” at a desired temperature, the refrigerant in the air conditioning system must be circulated at a higher rate, requiring more energy to operate the system. It is thus desirable to find a way to reduce the effect of the solar radiation RS on the condenser 10.

[0029] I have discovered that a solar radiation screen, specifically configured to block solar radiation from an air conditioner condenser, can improve the efficiency of the condenser. This in turn reduces the energy required by an accompanying air conditioning system to maintain a constant temperature of an indoor environmental space being cooled by the air conditioner. The solar radiation screen is particularly useful for an air conditioner condenser located on the roof of a building, but can also be used for an air conditioner condenser located in other locations.

[0030] Turning to FIG. 2, a schematic diagram depicts the various angles of incidence of solar radiation RS on the side of a condenser 10 of an air conditioner. The diagram depicts an exemplary solar radiation exposure scenario in a location in the northern hemisphere, wherein the sun typically shines on the southern exposure of the condenser. Throughout the day, as the sun rises and sets, it moves vertically (with respect to the side of the condenser) in an envelope 20 described by the overall arc

T. The overall arc can be identified by various segments. The first segment 21 covers a small arc θ1 through which the sum moves at dawn and dusk, and very little direct solar radiation impinges on the condenser. The second segment 22 covers an arc described by angle θ2, and identifies the early morning and early evening periods of solar radiation exposure, as for example from 5 a.m. to 7:30 a.m., and from 5:30 p.m. to 8 p.m. The third segment 24 covers an arc described by angle θ3, and identifies the mid-morning and late afternoon periods of solar radiation exposure, as for example from 7:30 a.m. to 10 a.m., and from 3 p.m. to 5:30 p.m. The fourth segment 26 covers an arc described by angle θ4, and identifies the mid-day period of solar radiation exposure, as for example from 10 a.m. to 3 a.m. This envelope 20 of solar radiation is an example of a typical summer solar radiation exposure for north America. A typical winter solar radiation exposure envelope may only cover the arc described by segments 21 through 24, and the period of time might be from 7 a.m. to 5 p.m.

[0031]FIG. 3 depicts a plan view of the air conditioner condenser 10 of FIG. 2, and shows an exemplary azimuthal (or horizontal) arc 30 through which the sun moves during the day. FIG. 2 essentially depicts the horizontal exposure of the sun on the condenser 10, corresponding to the vertical solar exposure of the condenser 10 depicted in FIG. 2. As in FIG. 2, the building “B” is depicted as being located in the northern hemisphere, such that the sun directly radiates the condenser 10 mostly on the southern exposure of the condenser. When the sun is in position I, corresponding to sunrise at 5 a.m., only the east side of the condenser 10 is exposed to direct solar radiation. From 5 a.m. until about 7 a.m., when the sun moves to position II, only the east side of the condenser is exposed to direct solar radiation, as depicted by segment 32. At about 7 a.m. the sun moves past position II towards position III, as indicated by segment 34, corresponding to the period between 7 a.m. and about 11 a.m. During this time, both the east side and the south side of the condenser 10 are exposed to direct solar radiation. When the sun is between positions III and IV (segment 35), corresponding to between 11 a.m. and 1 p.m., essentially only the southern side of the condenser 10 is exposed to direct solar radiation. Once the sun moves past position IV and towards position V (segment 36), both the south side and the west side of the condenser 10 are exposed to direct solar radiation. This occurs between 1 p.m. and 6 p.m. Finally, after about 6 p.m., the sun moves towards position VI, corresponding to sunset, during which time only the west side of the condenser 10 is exposed to direct solar radiation. As can be seen, the south side of the condenser 10 is exposed to direct solar radiation from about 7 a.m. until about 6 p.m., a total of 11 hours. For winter, the envelope 30 is reduced in size, and is rotated clockwise approximately 25 degrees (depending on the latitude at which the building is located). Thus, in the winter the sun will expose the east side of the condenser to solar radiation for a longer period of time, and the west side may not even be exclusively exposed absent concurrent exposure to the south side of the condenser.

[0032] When FIGS. 2 and 3 are viewed together, it can be seen that, in the example shown, the south side of the condenser 10 can be exposed to considerable solar radiation between the hours of 7;30 a.m. to 5:30 p.m. Accordingly, an air conditioner condenser solar radiation screen in accordance with the present invention is preferably configured to take into account the horizontal and vertical angles of the sun during the day, and during the different seasons of the year, so as to specifically prevent a significant portion of direct solar radiation from impinging on the air conditioner condenser (i.e., on the heat transfer plates of the condenser). Preferably, the solar radiation screen is configured such that it does not noticeably impede the flow of air into the condenser. It should be understood that FIGS, 2 and 3 are exemplary only, and are merely provided to convey the concept of how the solar radiation to which an air conditioner condenser can be exposed can vary with the time of the day, the seasons of the year, and the location on the earth of the condenser.

[0033] My invention includes a solar radiation screen for an air conditioner condenser. In one embodiment, the solar screen has a body supporting a plurality of solar blocking surfaces. The solar blocking surfaces are configured to block solar radiation from the condenser. Preferably, the solar blocking surfaces are configured to block at least about fifty percent of direct solar radiation which is anticipated as impinging on the solar radiation screen. More preferably, the plurality of solar blocking surfaces are positioned on the body in a position to account for anticipated directions at which solar radiation will directly impinge on the solar radiation screen when in use. For example, the solar blocking surfaces are positioned to account for the direction of the sun with respect to the solar screen and the condenser, as described and depicted with respect to FIGS. 2 and 3. In another embodiment my invention includes a perforated sheet of material which acts as a solar radiation screen for an air conditioner condenser. Preferably, the perforations are configured to allow less than half of the solar radiation anticipated as impinging on the solar radiation screen from passing directly to the condenser, thus blocking more than half of the direct solar radiation from the condenser.

[0034] Turning now to FIG. 4, an oblique diagram depicting a solar screen assembly 100 for an air conditioner condenser 10, in accordance with a first embodiment of the present invention, is shown. The condenser 10 is depicted as being located on the roof “R” of a building “B”, although this is not a requirement for the present invention to be effective in blocking solar radiation from the condesnser 10. The solar screen assembly as depicted comprises four solar screen panels 110, 120, 130 and 140. As suggested by FIG. 3, all four solar screen panels may not be required. For example, the fourth solar screen 140 could be eliminated with little to no detrimental effect, since direct solar radiation may not impinge on the north side of the condenser 10. Further, a solar screen panel can be provided only for the side of the condenser which is expected to receive the bulk of the direct solar radiation, which in FIG. 4 is the south panel 120. The solar screen panels 110, 120, 130 and 140 can be attached to the condenser 10 using clips 102 or other attachment devices (such as screws or the like).

[0035] I will now describe one of the solar screen panels, panel 110, in detail. It is understood that the other panels 120, 130 and 140 can all be configured similar to the solar screen 110. In this discussion I will refer to both FIGS. 4 and 5. FIG. 5 depicts a side elevation cross sectional view of the solar screen panel 110. The solar radiation screen 110 includes a support body 111 defining an inward side 106 configured to be placed proximate to the air conditioner condenser 10, and an outward side 108 configured to be placed proximate to a source of air “A” to be passed through the air conditioner condenser 10. The solar screen 1110 includes a plurality of solar radiation blocking surfaces 112 supported by the body 111. The radiation blocking surfaces 112 are preferably horizontally oriented. That is, the leading edge 125 and the trailing edge 127 of the solar blocking surfaces 112 are essentially horizontal with respect to the surface (roof “R”) on which the condenser is mounted. The solar blocking surfaces 112 are downward sloping from a point proximate the inward side 106 of the support body 111 to a point proximate the outward side 108 of the body. The solar blocking surfaces 112 are spaced apart from one another by a distance “h” to the allow the source of air “A” to essentially pass relatively freely over the solar blocking surfaces and through the condenser 10, to be exhausted as exhaust air “E”. Thus, the fan 12, driven by the motor “M”, can propel air “A” through the openings 109 formed between the solar blocking surfaces 112, past the heat transfer plates 14 of the condenser 10, to remove heat from the refrigerant passing in tubing 16. The air “A” is then exhausted from the condenser 10 as exhaust air “E”.

[0036] The support body 111 of the solar screen 110 comprises opposing side members 116, which span between the inward side 106 and the outward side 108 of the support body. The solar blocking surfaces 112 are defined by ends, and the side members 116 support the solar blocking surfaces at their ends. The solar screen 110 can further include at least one vertical support member 114 disposed between the side members 116 of the support body 111. The vertical support members 114 further support the solar blocking surfaces 112. As depicted in FIG. 5, the solar blocking surfaces 112 can be pivotally supported by the sides 116 and the vertical support members 114 by a pivot connection 118 to allow the mounting angle α1 of the solar blocking surface to be adjusted. The vertical support members 114 can also serve to stiffen the solar blocking surfaces 112 so that they are resistant to failure from fatigue (which can be induced by vibration from the fan 12), as well as to resist bending which can result from impact, as for example from hail. The vertical support members 114 can further serve to block direct solar radiation which impinges on the solar screen 110 from side angles, such as segments 34 and 36 of FIG. 3.

[0037]FIG. 5 also depicts the sun shining directly on the solar screen 110. The sun is shown inclined at an angle Ymin, which is the minimum angle of solar declination at which direct solar will be completely blocked by the solar blocking surfaces 112 of the solar screen. That is, when the sun is declined at an angle greater than Ymin, direct solar radiation will be prevented from impinging on the heat transfer plates 14 of the condenser 10. Likewise, when the sun is declined at an angle less than Ymin, direct solar radiation can impinge on the heat transfer plates 14 of the condenser 10. In most instances it is preferable to configure the solar blocking surfaces 112 of the solar screen 110 such that no solar radiation can impinge directly on the condenser 10 (or, to be more precise, on the heat transfer plates 14 of the condenser). This can be accomplished in a number of ways.

[0038] With respect to FIG. 6, a detail is shown depicting the geometry of two of the solar blocking surfaces 112 and 112′ of the solar screen 110 of FIG. 5. The view in FIG. 6 is a side elevation cross sectional view, as also depicted in FIG. 5. As shown, the solar blocking surfaces 112 and 112′ are separated by a horizontal distance “h”. Each solar blocking surface is defined by a horizontal length (i.e., the length between sides 116 of the solar screen, or between vertical members 114, as in FIG. 4), and a width “W” perpendicular to the horizontal length. Each solar blocking surface 112, 112′ is also mounted at an angle α1 with respect to a horizontal surface (such as roof “R”) on which the condenser 10 is supported (as shown in FIG. 5). The spacing “h” of the solar blocking surfaces 112 and 112′, as well as their angle of mounting α1, and the width “W” of the solar blocking surfaces, all affect the ability of the solar screen to block direct solar radiation from the condenser 10. As depicted in FIG. 6, a gap “g” can occur which allows solar radiation to directly impinge on the condenser (not shown in FIG. 6) as the sun moves through angle Ymin.

[0039] As previously mentioned, preferably the solar blocking surfaces 112, 112′ are designed to block direct solar radiation from impinging on the condenser. In this case the gap “g” will be equal to zero. This can be accomplished by selecting two of the three variables (i.e, the spacing “h”, the mounting angle α1, and the width “W”) and then calculating the third variable. This can be accomplished as follows. As seen from FIG. 6, a solar blocking surface blocks direct solar radiation over a vertical distance of W(sin α1). Thus, when the vertical spacing “h” is equal to W(sin α1), the gap “g” will be zero, and no direct solar radiation will pass through the solar screen. In this case, Ymin is zero degrees. Accordingly, the width “W”, the height “h”, and the angle of mounting α1 can be selected or predetermined to prevent direct solar radiation from passing between the solar blocking surfaces and to the condenser. When W and α1 are selected, then the spacing “h” is determined from h=W(sin α1); when “h” and α1 are selected, then the width “W” is determined from W=h/(sin α1); and when “h” and “W” are selected, the angle of mounting α1 of the solar blocking surface is determined from α1=h/W. In this last instance, if the spacing “h” between the solar blocking surfaces is greater than the width “W” of the Solar blocking surface, then it is not possible to completely block all of the direct solar radiation from the condenser using the solar blocking surfaces.

[0040] Turning to FIG. 12, a schematic diagram similar to FIG. 5 is depicted. The diagram in FIG. 12 depicts a side elevation view of the solar blocking surfaces 112 and 112′ of FIG. 5. Each solar blocking surface is defined by an upper surface 143 upon which solar radiation can directly impinge when the solar screen is in use, and an opposite lower surface 141. Solar radiation RS1 at a shallow angle is blocked from directly impinging on the heat transfer plate 14 of the condenser, but can be reflected off of the upper surface 143 of the solar blocking surface 112′ to indirectly impinge on the heat transfer plate 14. Further, solar radiation RS2 at a steeper angle is blocked from directly impinging on the heat transfer plate 14 of the condenser, but is reflected off of the upper surface 143 of the solar blocking surface 112′ to indirectly impinge the lower surface 141 of the solar blocking surface 112. The solar radiation can then be secondarily reflected from the lower surface 141 of the solar blocking surface 112 to the heat transfer plate 14. In either case, this indirect radiation which can impinge on the heat transfer plate 14 can reduce the effectiveness of the solar screen in blocking solar radiation from the condenser.

[0041] This problem of indirect, reflected solar radiation can be addressed in a number of ways. One technique is to make the upper surfaces 143 of the solar blocking surfaces 112 as light diffusing surfaces. In this way only part of the solar radiation (RS1) will be reflected to the heat transfer plates 14. Further, the lower surfaces 141 of the solar blocking surfaces 112 can be made as light diffusing surfaces. In this only part of the solar radiation (RS2) which is reflected from the upper surface 143 to the lower surface 141 will be reflected to the heat transfer plates 14. Further, both the upper and lower surfaces can be light diffusing surfaces to address radiation reflected from either surface. An example of a light diffusing surface is a surface painted in a flat (non-gloss) white paint. Materials of construction for the solar screen 110 which can provide for a heat reflective, light diffusing surface include nylon (preferably white) and polycarbonate (also preferably white).

[0042] Another approach to the problem of indirect solar radiation is to mount the solar blocking surfaces 112 at a mounting angle such that no solar radiation can be reflected directly from the upper surface 143 of a solar blocking surface to the heat transfer plate 14 of the condenser 10 (not shown). Such a configuration is depicted in FIG. 13, which is a variation of FIG. 6. As can be seen, solar radiation SB0 which enters the opening 109 between solar blocking surfaces 112 and 112′ at the minimum angle (i.e. zero degrees) will be reflected from the upper surface 143 of solar blocking surface 112′ to the lower surface 141 of solar blocking surface 112. While this still allows some solar radiation to be secondarily reflected from the lower surface 141 of solar blocking surface 112 to the heat transfer plates 14, by making the lower surface 141 a light diffusing surface the effect of secondarily reflected radiation can be significantly reduced.

[0043] Yet another approach to addressing the problem of secondary reflected solar radiation is to configure the lower surface 141 of the solar blocking surface 112 to reflect solar radiation away from the condenser plates 14. An example of one such solar blocking surface is depicted in FIG. 15. The solar blocking surface 510, depicted in a side elevation view, has a lower surface 512 having reflective facets 514. The reflective facets tend to reflect solar radiation, which can be reflected to the lower surface 512 by the upper surface of an adjacent solar blocking surface, away from the heat transfer plates of a condenser (not shown) and out of the opening formed between adjacent solar blocking surfaces. Since the reflective facets 514 can potentially cause turbulence in air moving between two adjacent solar blocking surfaces 510, the facets 514 can be covered with a transparent sheet 516 which serves to reduce the turbulence, yet which still allows solar radiation to be reflected by the facets 514.

[0044] Turning briefly to FIG. 9, one method of securing the solar screen 110 in proximity to the condenser 10 is shown. The view in FIG. 9 is similar to the view in FIG. 5, being a partial side elevation view of the evaporator 10 and the solar screen 110. The evaporate here is shown comprising a housing 11, which can be for example a sheet metal housing. The heat transfer plates 14 and refrigerant coils 16 are housed within the housing 11, and the condenser is supported on the roof “R” of the building “B”. The solar screen 110 is supported on the roof “R” by a foot 140, and is held in proximity to the condenser 10 at the top of the solar screen by a retaining clip 132. The retaining clip 132 has a first curved end 134 which can engage the metal housing 11 of the condenser 10. The retaining clip has a second end comprising an indentation 136 and a release tab 138. The indentation 136 can fit within a recess 130 formed in the side 116 of the solar screen 110 to thereby hold the solar screen 110 in proximity to the condenser 10. The retaining clip 132 can be fabricated from a resilient material, such as spring steel or nylon, such that the indentation 136 in the clip 132 can be released from the recess 130 by pulling the tab 138 in an outward and upward direction indicated by the arrow “P”. In this way the solar screen 110 can be easily removed from the condenser 10, as for example to allow access to the condenser for maintenance and repairs, and for cleaning of the solar screens.

[0045] While air conditioner condensers have thus far been depicted as being housed in a generally rectangular configuration (see for example condenser 10 of FIG. 4), in some instances a condenser is configured in a round shape. FIG. 7 depicts a plan view of a round condenser 40 having a fan 44 for moving air through the condenser. The condenser 40 is depicted as being provided with a solar radiation screen 200 in accordance with a second embodiment of the present invention. The solar radiation screen 200 comprises a plurality of hingedly connected adjacent solar screen panels 202 through 212. Two of the panels, panels 202 and 203, are depicted in an isometric view in FIG. 8. Each of the panels 202 through 212 comprises a support body 230 defining an inward side 232 configured to be placed proximate to the air conditioner condenser 40, and an outward side 234 configured to be placed proximate to a source of air to be passed through the air conditioner condenser. Each panel also includes a plurality of solar blocking surfaces 212 supported by the body 230. The solar blocking surfaces are downward sloping away from the condenser 40 (i.e., from the inward side 232) when the panel is located proximate the condenser. The solar blocking surfaces 212 are spaced apart from one another to form openings 216 and thus allow the source of air to pass over the solar blocking surfaces 212 and through the condenser 40. The design criteria for the solar blocking surfaces 212 can be determined in the manner described above with respect to the Solar blocking surfaces 112 of the solar screen 100 of FIGS. 4-6 and 12-14. Such design criteria include the mounting angle (α1) of the solar blocking surfaces, the spacing (“h”) between the solar blocking surfaces, and the width (“W”) of the solar blocking surfaces. The panels can also be provided with vertical support members 214 which function in the same manner as the vertical support members 214 of the solar screen 110 of FIGS. 4 and 5.

[0046] The adjacent panels 202 through 212 of the solar screen 200 can be hingedly joined together in a number of different manners. For example, the individual panels can be provided with hinge mounting holes 222 (FIG. 8), which then allow one panel 202 to be joined to another 203 using hinge clips 224. The panels can also be hingedly connected to one another using a flexible joint, such as a fabric tape. When the panels are fabricated from molded plastic, the flexible joint can be a molded plastic hinge which forms an integral part of two adjacent panels. In this way a number of the panels can be molded in a joined fashion, allowing for simplified installation of the panels around the condenser 40.

[0047] A third embodiment of the present invention is depicted in FIGS. 10 and 11, and provides for a solar radiation screen 300 for an air conditioner condenser. The screen 300 can be fabricated by stamping a sheet of material. FIG. 10 depicts an isometric view of the solar screen 300, and FIG. 11 depicts a side elevation sectional view of the screen of FIG. 10. The solar radiation screen 300 comprises a sheet of material 310 having an inward side 304 configured to be placed proximate to an air conditioner condenser (not shown), and an outward side 306 configured to be placed proximate to a source of air (not shown) to be passed through the air conditioner condenser. The sheet of material 310 defines a plurality of openings 312 (Fig, 11) through which the source of air can pass to the condenser. The openings 312 are overhung by solar blocking surfaces 320 which are preferably formed from the sheet of material 310. The solar blocking surfaces 320 can also comprise individual components which are attached to the sheet of material 310. The solar blocking surfaces 320 slope downward from a point proximate the outward side 306 of the sheet of material 310 to a point distal from the outward side of the sheet of material. Preferably, the sheet of material 310 is fabricated from a flexible or contourable material, such as plastic or thin metal, allowing the sheet to be contoured to fit a contoured shape of a condenser, such as the round condenser 40 of FIG. 7.

[0048] An advantage of the solar screen 300 of FIGS. 10 and 11 over the solar screen 110 of FIG. 5 is that the problem of indirect solar radiation, described above with respect to FIGS. 12 and 13, is virtually eliminated. Further, the solar blocking surfaces prevent a large amount of direct solar radiation from passing through the solar screen, and the direct solar radiation which does pass through the screen will pass through at a low solar angle of incidence when the effect is not significant. However, this effective solar blocking is generally achieved by limiting the distance that the solar blocking surfaces 320 are pushed out from the front surface 306 of the screen 300. This in turn can result in restricted airflow through the openings 312. When the solar blocking surfaces 320 are pushed out too far, then a larger opening 312 is formed, allowing more air to flow through the opening, but also allowing more direct solar radiation to enter the opening from the beneath the solar blocking surface 320.

[0049] Further, when the solar blocking surfaces 320 are formed by stamping the sheet of material 310, the solar blocking surfaces will generally be formed like small “tents” having ends 318 which join the solar blocking surface 320 to the main sheet of material 310. If the solar blocking surfaces 320 are pushed out quite far from the outer surface 306 of the sheet 310, then the ends 318 can be torn, allowing direct solar radiation to more easily pass through the screen 300. Accordingly, it is preferable to limit the size of the solar blocking surfaces 320 in the solar screen 300 when the solar blocking surfaces are formed by stamping the sheet of material 310. When the solar blocking surfaces 320 are attached as separate components to the sheet of material 310, then these concerns can be easily overcome by sizing the solar blocking surfaces 320 accordingly (i.e., to preferably completely block the openings 312 from solar radiation directly impinging on the solar screen 300 at any anticipated angle of incidence).

[0050] One technique for improving the performance of the solar screen 300 is to make the outer surface 306 (i.e., the surface directly exposed to the solar radiation) a reflective surface. For example, if the sheet of material 310 is a sheet of stainless steel having at least one side which is polished, then the polished side can be selected as the outward side 306 of the solar screen 300.

[0051] A fourth embodiment of the present invention is depicted in FIG. 16, and provides for a solar radiation screen 400 for an air conditioner condenser which can be fabricated by stamping a sheet of material. The solar screen 400 comprises a sheet of material 410 defining a total area, as for example, the width of the sheet multiplied by the height of the sheet. The sheet of material 410 has an inward side 412 configured to be placed proximate to an air conditioner condenser (not shown), and an outward side 414 configured to be placed proximate to a source of air (not shown) which is to be passed through the air conditioner condenser. The sheet of material 410 defines a plurality of openings 416 through which the source of air can pass to the condenser. The openings collectively define an opening area (i.e. the total frontal area of all of the openings on one side of the sheet of material). While the opening area can be between 15% and 90% of the total area, preferably, the opening area is less than half (or 50%) of the total area. More preferably the opening area is less than one third (or 33%) of the total area of the sheet of material.

[0052] Although the solar screen 400 may not block all direct solar radiation from impinging on an air conditioning condenser, it can block a significant portion of the solar radiation, thus improving the performance of the condenser. Reducing the opening area of the openings 416 will further reduce the solar radiation which can pass through the screen 400 to the condenser. However, as the opening area is further reduced to block additional solar radiation, the screen 400 can begin to noticeably restrict air flow through the screen and to the condenser, adversely affecting the performance of the condenser. Accordingly, in selecting the opening area of the screen 400, both of these factors (solar radiation blocking effect and restriction of air flow) should be considered. While the solar screen 400 may allow some solar radiation to pass directly through the screen (unlike the solar screen 110 of FIGS. 5 and 6 when the gap “g” is zero), the screen 400 essentially eliminates the problem of indirect or reflected solar radiation, as discussed above with respect to FIGS. 12 and 13.

[0053] One method to improve the performance of the solar screen 400 is to configure the outward side 414 of the sheet of material 410 (i.e., the side intended to be exposed directly to the solar radiation) to reflect a majority of the solar radiation impinging on the outward side of the sheet of material. For example, if the sheet of material 410 is a sheet of stainless steel having at least one side which is polished, then the polished side can be selected as the outward side of the solar screen.

[0054] A further advantage of the solar screen 400 is that it can be fabricated from a flexible or contourable material, such as a relatively thin sheet of metal or plastic. In this way the solar screen can easily be contoured to fit a contoured shape of a condenser, such as the round condenser 40 of FIG. 7. Since the screen 400 can also be easily manufactured using a simple stamping process, and a significant quantity of solar radiation can be reflected by coating or polishing the outer surface with a reflective material, and further since the solar screen 400 essentially eliminates the problem of reflected radiation (discussed above), the solar screen 400 can be an attractive choice.

[0055] While the above invention has been described in language more or less specific as to structural and methodical features, it is to be understood, however, that the invention is not limited to the specific features shown and described, since the means herein disclosed comprise preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted in accordance with the doctrine of equivalents.

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US8028691 *Oct 27, 2008Oct 4, 2011Johnson Screens, Inc.Passive solar wire screens for buildings
US8448458Nov 15, 2010May 28, 2013James Peter HammondSolar collector and solar air conditioning system having the same
US8596261Sep 29, 2011Dec 3, 2013Bilfinger Water Technologies, Inc.Passive solar wire screens for buildings
US20100319380 *Mar 15, 2010Dec 23, 2010Mitsubishi Electric CorporationOutdoor unit for air conditioner
WO2009156331A2 *Jun 18, 2009Dec 30, 2009Reginald Ian WilliamsSolar energy generator
Classifications
U.S. Classification62/259.1, 62/428
International ClassificationF24F1/00, F24F13/20, F24J2/40
Cooperative ClassificationF24F1/50, Y02B10/20, F24J2/407, F24F2005/0064, F24F1/58, Y02E10/40
European ClassificationF24F1/58, F24F1/50, F24J2/40D, F24F13/20