APPARATUS FOR PREHEATING VENTILATION AIR FOR A BUILDING

Abstract: Ventilation air for a building is preheated by providing on a south facing wall 10 a sunlight-­ absorbent corrugated collector panel 16 with the corrugations vertical, thus defining vertical channels 18 between the panel 16 and the wall 10, and vertical grooves 20 on the exterior of the panel. Outside air passing upwardly along the channels 18 is heated by a combination of solar heat from the panel 16 and heat being lost from the interior of the building through the wall 10. Air passing upwardly along the grooves 20 is heated by solar heat from the panel 16. The thus heated air is withdrawn from the channels 18 and grooves 20 and expelled into the interior of the building.

Description: This invention relates generally to an apparatus for controlling the entry of ventilation air into a building, and preheating the air with a combination of solar heat and the natural building heat loss. Commercial and industrial buildings require ventilation, and it is common for the natural leakage around doors, wall-ceiling joints, etc. found in standard building construction to allow sufficient ventilation air to enter the building. A pressure drop from the exterior to the interior of the building can arise from many factors, such as high winds, exhaust fans and combustion air for fuel-burning furnaces. This tends to draw outside air into the building through any crack or opening. The problem with the conventional approach is that the amount of ventilation air is not controlled, and additional heat must be provided to heat the outside air to room temperature during the autumn, winter and spring months. This problem has typically been solved by installing air make-up fans with gas or electric heaters to heat the incoming air. When solar panels are used to heat a building, air is re-circulated from the building through the panels and then back again to the building. The efficiency of a solar collector is maximized when the temperature of the air entering the collector is the same as the ambient temperature. Under normal winter conditions, the ambient temperature is lower than the room temperature, and therefore a recirculating solar collector operates at a much reduced efficiency level in wintertime. My own earlier Canadian patent 1,196,825, issued November 19, 1985 and entitled "Method for preheating Ventilation Air in a Building" describes a method and apparatus which avoid using consumable energy sources like gas or electricity to heat incoming air for a building, and instead of simply recirculating interior air from the building through a solar collector and back to the building, it introduces fresh make-up air for ventilation purposes into the interior of the building after first passing the air through a solar collector located on a south-facing wall of the building. The solar collector in my earlier patent consists of glazing over a darkened wall. Air moving means, such as a fan and duct arrangement, is used to gather air at the top of the solar collector and force it into the building (see also FR-A-2509023). I have now devised a simpler and less expensive structure for accomplishing essentially the same thing as is accomplished by the apparatus disclosed in CA-A-1,196,825 and FR-A-2509023. More specifically, this invention provides apparatus for preheating ventilation air for a building having a south facing wall 10 through which heat from the interior of the building escapes, the apparatus including: a sunlight-absorbent collector means 16 provided on the south facing wall 10, air-moving means 31 having an inlet at the top of the collector means 16 for receiving air that has been heated during upwards passage through the collector means 16, and having an outlet within the interior of the building, the collector means 16 comprising a corrugated collector panel arranged with the corrugations running substantially vertically, thus defining a plurality of substantially vertical external grooves 20 on the exterior of the panel in which air can be heated, access means being provided by which air heated in the external grooves 20 enters the inlet, characterized in that the collector means 16 is unglazed and is exposed to the ambience. For a better understanding of the present invention and to show how it may be carried into effect, reference will now be made, by way of example, to the drawings in which: Figure 1 is a perspective view of a make-up or ventilation air system for a building, constructed in accordance with this invention; Figure 2 is a sectional view through the structure of Figure 1, taken at the line 2-2; Figures 3, 4, 5 and 6 are horizontal sectional views similar to Figure 2, showing four alternative configurations for the collector; and Figure 7 is a vertical sectional view through the air-collection plenum shown at the top in Figure 1. Attention is first directed to Figure 1 which shows a partly broken-away perspective view of a system for carrying out the present invention. A building wall is shown in part at 10 in the Figures, this being typically a block construction, or a block-and-brick composite structure. As with all building walls, even those well-insulated, a steady heat loss is experienced through the wall when the outside temperature is below the inside temperature. The wall 10 has an outer surface 12 to which is affixed a mounting plate 14. The plate 14 may be mounted by Z-bars or the like, thus spacing the plate away from the wall 10 to allow for irregularities in the latter Secured to the mounting plate 14 is a corrugated collector panel 16 which is coated on the outside with a heat-absorbent material, such as black paint. The collector panel 16 is disposed with the corrugations running vertically, thus defining a plurality of substantially vertical channels 18 between the panel and the wall 10 (see Figure 2), and further defining a plurality of substantially vertical grooves 20 on the exterior of the panel 16. At the top of the panel 16 there is provided an air collection plenum 22 which can be rectangular in section. In one version of the invention, both the vertical channels 18 and the vertical grooves 20 open to the underside of the plenum 22, so that air which is heated during upward passage through the channels and the grooves can be collected therein. In another version of the invention, only the vertical grooves 20 open to the underside of the plenum 22, and the channels 18 do not communicate with the plenum. Communicating with the internal chamber of the plenum 22 is a fan housing 30 which contains a conventional fan or air-impeller 31 and includes motorized dampers 32 which allow air from the interior of the building to be mixed with heated air coming from the plenum 22. Communicating with the housing 30 is a fabric air duct 34 which is preferably flame retardant and made of polyfabric, the duct 34 being suspended by a plurality of duct hangers 36 from a suitably strung support wire or rod 38. The air duct 34 has a plurality of openings 40 through which the heated outside air can pass from the duct 34 into the interior of the building. By appropriately sizing the openings 40, the air can enter the interior of the building as a high-velocity air jet, thus promoting good mixing within the interior of the building, and minimizing stratification. It is preferred that the duct 34 be located at ceiling level within the building, for the sake of convenience. However, other levels could also be utilized. The fan within the housing 30 would typically be sized to meet the ventilation requirements and eliminate the negative pressure problem if such exists. A positive pressure can be achieved with outside air entering the building through the fan in the housing 30, the air being heated by the solar heat, the building heat loss, and stratified heat found near the ceiling. Air can then leave the building through the cracks and openings where previously air had entered. It will be noted that the plenum 22 overhangs the corrugated panel 16, and thus a shadow is cast upon the panel 16 during late spring and early summer, when the sun at mid-day is quite high in the sky. This automatically avoids solar heating of the air during the hotter portion of the year. Alternatively, as shown in Figure 1, the plenum 22 can be provided with a by-pass damper 43 which can be opened when heating is not required, so that the fan or air-impellar 31 draws fresh air in directly from outside, and does not capture any heated air moving upwardly along the wall in the grooves 20 or channels 18. It will thus be appreciated that, in a combination operation, outside air passes upwardly along the channels 18 and the grooves 20, thence into the space defined under the hood 22. In the upward passage along the channels 18, the air is heated by a combination of solar energy transmitted by conduction through the corrugated panel 16 and heat escaping from the inside of the building through the wall 10. The air passing upwardly along the grooves 20 is heated by conduction from the corrugated panel 16, using solar heat that normally would be lost to the atmosphere. The heated air is then withdrawn from the channels and grooves into the space beneath the hood 22, thence impelled by the fan 31 into the interior of the building. The profile of the corrugations defined by the collector 16 can vary, depending upon the air volume required, the area of the south wall, and the general wind conditions. Larger air volumes would require most or all of the air to be drawn from the grooves 20, whereas smaller air volumes would use more air from the channels 18, or equal quantities from the grooves and channels. The embodiment illustrated in Figure 3 is one which provides a greater air volume behind the collector (i.e. in the channels 18) than in front of the collector. The embodiment of Figure 4 has only slightly greater volume in the channels 18 than in the grooves 20. The embodiment of Figure 5 has more volume in the grooves 20 than in the channels 18. The embodiment illustrated in Figure 6 is similar to that illustrated in Figure 2, and has deep grooves for very windy locations. Any of the configurations shown in Figures 3-6 could be used for groove collection alone, or for collection of air moving through both the grooves and the channels. This would depend upon volume required, and wind exposure conditions. Finally, it would be possible to use the structure of the collector panel, possibly including the mounting plate 14, to constitute the south wall itself, without having to mount the structure into an existing wall. Attention is now directed to Figure 7, which shows that the rectangular plenum 22 can be provided with an adjustable baffle 47, adapted to close off the tops of the channels and grooves defined by the collector 16. A manual fastener 49 is provided to secure the baffle 47 in any desired position. The grooves and channels would be closed off in hot, summer conditions when no heating of the building is required. At such times, the by-pass damper 43 would be open. Where reference has been made to a south facing wall, this should be understood to mean a wall which faces the sun for a significant part of the day. Thus, for buildings in the southern hemisphere, the expression "south facing" should be read as "north facing".

Claims: 1. Apparatus for preheating ventilation air for a building having a south facing wall 10 through which heat from the interior of the building escapes, the apparatus including: a sunlight-absorbent collector means 16 provided on the south facing wall 10, air-moving means 31 having an inlet at the top of the collector means 16 for receiving air that has been heated during upwards passage through the collector means 16, and having an outlet within the interlor of the building, the collector means 16 comprising a corrugated collector panel arranged with the corrugations running substantially vertically, thus defining a plurality of substantially vertical external grooves 20 on the exterior of the panel in which air can be heated, access means being provided by which air heated in the external grooves 20 enters the inlet, characterized in that the collector means 16 is unglazed and is exposed to the ambience. 2. Apparatus as claimed in claim 1, characterized in that the collector panel 16 further defines a plurality of substantially vertical channels 18 between the panel 16 and the wall 10, the channels 18 having open bottoms and being adapted to deliver air to the air-moving means 31, whereby air can pass upwardly through the channels 18 and be heated by a combination of solar heat and heat lost through the wall 10 from the interior of the building. 3. Apparatus as claimed in claim 1 or 2, characterized in that the outlet is situated at an upper region of the interior of the building. 4. Apparatus as claimed in and one of claims 1 to 3, characterized in that the air-moving means 32 includes hood means 22 overhanging the panel 16 and shading the same from the sun's rays when the sun is high in the sky. 5. Apparatus as claimed in any one of the preceding claims,characterized in that the inlet is adjustable in size.

Inventors: HOLLICK, JOHN C.
Applicants: HOLLICK, JOHN C.
Application year: 1989
Main classification: F24J2
IPC codes: F24J2