DEHUMIDIFICATION TECHNICAL FIELD

The present invention relates to a self-contained air delivery unit for cooling or heating outdoor air and return air supplied to a building, largely using the refrigeration cycle, with integration of dedicated dehumidification of the outdoor air so delivered.

BACKGROUND Buildings may have air conditioning or ventilation systems in which the air is heated or cooled by externally located air delivery units . The primary cooling and heating equipment of such air delivery units may be largely contained within a single weather-proof unit or piece of apparatus, known as a packaged air conditioner, or PAC, which is externally located. This primary cooling and heating equipment can include indoor refrigeration cycle components such as compressors, reversing valves (for heating) , evaporators and condensers, and associated fans. PACs are factory manufactured and tested (as opposed to assembled on site) and therefore benefit from economies of scale of both mass production (low manufacturing costs) and large scale product development (research costs spread across multiple units), as well as from improved reliability (they are built and assembled in a controlled environment, and tested before shipment) and standardisation of parts (reduced maintenance costs) . Additionally, PACs reduce installation time on site (they are simply craned into place and then connected to ducting, controls and power) .

PACs cool or heat return air from a building and outdoor air, or more typically a blend of the two usually made up predominantly of return air (unless delivering economiser mode "free cooling" of predominantly cool outdoor air in cooling mode) , before delivering this cooled or heated air to the building. The greater the temperature and/or absolute humidity of the outdoor air so delivered, the greater the amount of cooling required of the blend of outdoor air and return air to sufficiently dehumidify the air supplied to the building in order to prevent the humidity in the building from rising beyond prescribed limits. This is important in such spaces as supermarkets, where low indoor humidity levels are preferred so as to reduce frosting on the refrigeration cabinet heat exchangers, as such frosting results in poor refrigeration cabinet temperature control, as well as substantially increased refrigeration cabinet power consumption and increased product spoilage. After being cooled, to achieve dehumidification, the supply air from the air delivery unit may be reheated so as not to overcool the inside of the building. This process of cooling the blend of supply and return air to dehumidify it, and then reheating it so that it is not overly cool when delivered into the building, consumes substantial amounts of energy.

As the outdoor air introduced to buildings is often the primary source of humidity entering a building, buildings can be fitted with so-called "dedicated outdoor air systems" (DOAS) that provide dedicated, or largely dedicated, cooling and dehumidification of the outdoor air delivered to the building. Dedicated cooling and dehumidification of the outdoor air provides potential for substantial energy savings when compared to cooling and dehumidifying the blend of outdoor air and predominantly return air, as it is more effective at removing the moisture that is introduced by the outdoor air and it reduces the need to reheat the blend of outdoor air and return air so as not to overcool the inside of the building. However, DOASs have drawbacks, including that they require additional space, structural support, ducts, dampers, controls and electrical wiring to the building's normal operation HVAC system. The above references to the background art do not constitute an admission that the art forms a part of the common general knowledge of a person of ordinary skill in the art. The above references are also not intended to limit the application of the apparatus as disclosed herein.

SUMMARY OF THE DISCLOSURE

In some embodiments, there is disclosed a package air conditioning unit for conditioning air in a space. The apparatus may include a first arrangement for receiving a first air stream substantially from outside the space and a second air stream substantially from the space. The apparatus may also include a first heat exchanger for conditioning the first air stream and a second heat exchanger, the first arrangement being configured such that the first air stream is conditioned prior to passing through the second heat exchanger. In at least one embodiment, a body defines an

interior cavity containing the first arrangement.

In some forms, the first arrangement is configured such that the first and second air streams are combined to form a combined air stream before passing through the second heat exchanger.

In some forms, the first arrangement further

comprises a third heat exchanger configured such that the combined air stream also passes through the third heat exchanger .

In some forms, the combined air stream is discharged into the space.

In at least one embodiment, conditioning of the first air stream dehumidifies that air stream. In at least one embodiment, the apparatus further comprises a second arrangement for receiving and

discharging at least a third air stream substantially from and to outside the space. In at least one embodiment, the second arrangement is contained within the body.

In at least one embodiment, the second arrangement comprises a fourth heat exchanger configured such that the third air stream passes through the fourth heat exchanger.

In some forms, the fourth heat exchanger is fluidly connected to the first heat exchanger. In some forms, the fourth heat exchanger is fluidly connected to the second heat exchanger. In some forms, the fourth heat exchanger is fluidly connected to the third heat exchanger.

In some forms, the apparatus further comprises a third arrangement for receiving and discharging at least a fourth air stream substantially from and to outside the space .

In some forms, the third arrangement is contained within the body.

In some forms, the third arrangement comprises a fifth heat exchanger configured such that a fourth air stream passes through the fifth heat exchanger. In some forms, the fifth heat exchanger is fluidly connected to the second heat exchanger.

In some forms, the fifth heat exchanger is fluidly connected to the third heat exchanger.

In at least one embodiment, the second arrangement further comprises a first compressor, the first compressor being fluidly connected to the fourth heat exchanger. In some forms, the third arrangement further

comprises a second compressor, the second compressor being fluidly connected to the fifth heat exchanger. In some forms, the first heat exchanger is able to absorb heat from the first air stream.

In at least one embodiment, the third heat exchanger rejects to the combined air stream at least a portion of the heat absorbed by the first heat exchanger from the first air stream.

In some forms, the second heat exchanger is able to absorb heat from the combined air stream.

In some forms, the third heat exchanger emits to the combined air stream at least a portion of the heat

extracted by the second heat exchanger from the combined air stream.

In some forms, the first arrangement further

comprises at least one fan that discharges the combined air stream to the space.

In at least one embodiment, the second or third arrangement further comprises at least one fan that

discharges at least one of the third and fourth air

streams to outside the space.

In at least one embodiment, the body forms the package air conditioning unit.

The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description

BRIEF DESCRIPTION OF THE DRAWINGS Further embodiments of the present apparatus will become apparent from the following description, which is given by way of example only, and with reference to the accompanying drawings in which: Fig. 1 shows the front and side section views of typical Package Air Conditioning Unit (PAC) of the prior art; and

Fig. 2 shows the front, side and section views of a PAC with an integrated dedicated outdoor air system.

DETAILED DESCRIPTION

Disclosed herein is an apparatus for integrating a DOAS into a PAC drawing return air from and delivering supply air to a space. The space may comprise the interior space (s) of buildings such as hospitals, enclosed shopping malls, supermarkets, factories, high rise buildings, etc.

The DOAS apparatus, located largely in a PAC, cools and dehumidifies , or heats, the outdoor air that is then blended with return air that has been delivered to the PAC, whereafter the blend of return air and outdoor air may be further cooled and/or heated (and thereafter potentially reheated) in the PAC before being delivered as supply air to the interior space of a building. Integrating such dedicated (or largely dedicated) dehumidification, cooling and heating apparatus for the outdoor air (or predominantly for the outdoor air) into the PAC provides substantial potential to save on capital costs, improve performance, reduce running costs, and minimise maintenance costs, due, primarily, to the economies of scale for manufacture and product development, as well as to the controlled manufacture and test environments, and standardisation of parts.

Additionally, largely dedicated cooling, dehumidification and heating of the outdoor air provides substantial potential for energy savings. One reason for this is that the outdoor air supplied to a building is often the primary source of humidity introduced into the building. It is far more efficient to remove this humidity from the outdoor air by means of a dedicated (or largely dedicated) outdoor air heat exchanger rather than by means of a heat exchanger that largely cools a blend of predominantly return air mixed with outdoor air. Another reason is that the heat exchanger that largely cools or heats a blend of predominantly return air mixed with air supplied by the DOAS is subject to greatly reduced temperature fluctuations of the blended airstream flowing onto it than if the outdoor air stream had not been precooled and dehumidified or preheated. This not only increases efficiency but also increases the outdoor temperature operating range of the equipment, making it suitable for a greater field of climatic environments, and additionally provides potential for greater and more controlled cooling and dehumidification and/or heating of the blended air. A further advantage is that the need and extent to which the supply air has to be reheated before being delivered to the building is often reduced substantially thereby further reducing system energy requirements . In instances where the building would otherwise be overcooled, additional energy savings can be achieved if, in order to dehumidify the outdoor air supplied to the building, the heat (or a proportion thereof) removed by the dedicated (or largely dedicated) outdoor air heat exchanger is transferred to reheat the supply air, as this is "free" heat. Similarly, in instances where the building would otherwise be overcooled and where the primary source of humidity is inside the building, additional energy savings can be achieved if, in order to dehumidify the blend of predominantly return air mixed with outdoor air, the heat (or a proportion thereof) removed by the heat exchanger that largely cools the blend of predominantly return air mixed with outdoor air is transferred to reheat the supply air, as this is "free" heat. Consequently, a highly beneficial heat exchanger arrangement would be one whereby the outdoor air supplied to the building could potentially first be dehumidified by a first heat exchanger (the dedicated outdoor air heat exchanger) before blending with return air and then passing through a second heat exchanger, which may cool (and dehumidify if necessary) the blend of return air mixed with outdoor air, before finally passing through a third heat exchanger, which may reheat the supply air stream to the building if necessary using, at least in part, heat removed from the first and/or the second heat exchangers. This would allow the supply air delivered to the building to be sufficiently dehumidified and to be of an appropriate temperature to satisfy the humidity and temperature requirements of the space, and would achieve this by reheating the supply air using, at least in part, "free" heat that had been removed from the outdoor air and/or return air streams in order to dehumidify them.

Reference numerals in the following description represent like components or features in the related figures . Referring now to Fig. 1, sections i-a, i-b, ii-a and ii-b show an example of a PAC (31) of the prior art. At least one supply air fan (1) that draws supply air stream (7) from suction chamber (2) through a filter (3) and heat exchanger (4) to be discharged through an air outlet (5) into supply duct (6) . Return air (13) is drawn into the suction chamber (2) through an air inlet (8) from return duct (9) . Outdoor air (14) is drawn into the suction chamber (2) through outdoor air inlet (10) from the outdoors (11) via weather cowl (12) . The flow rates of the return air (13) and the outdoor air (14) are regulated by return air damper (15) and outdoor air damper (16), respectively, which may be adjusted by electric actuators (not shown) . Transition pieces (17) typically join the supply air

(6) and return air (9) ducts to spigots surrounding air outlet (5) and the air inlet (8), respectively. Components (1, 2, 3, 4, 15, and 16) are largely housed in a largely thermally insulated casing (20) . At least one compressor (21), controlled by controller (22) in control panel (23) , is connected via refrigeration pipes and associated refrigeration components (not shown) to heat exchanger (4) and to heat exchanger (27) . At least one fan (24) draws air stream (26) from the outdoors (11) through heat exchanger (27) to be discharged to the outdoors via at least one air outlet (25) . Supply duct (6) and return duct (9) penetrate roof sheeting (28), supported by purlins (29), via upstands (not shown) with suitable under-flashing and over-flashing to seal to the roof sheeting (28) . The PAC (31) typically stands on a platform (30) supported by platform legs (33) connected to roof beams (32) via seals (not shown) in roof sheeting (28) .

Referring now to Fig. 2, sections i-a, i-b and ii show a PAC (31a) in accordance with this disclosure. A first air stream (14), in the form of outdoor air, is drawn substantially from the outdoors (11) into suction chamber (2) . A large portion of the outdoor air is outdoor air, or fresh air. The outdoor air (14) is primarily received from outside the space. The outdoor air (14) is drawn through an outdoor air inlet with filter (10a) via outdoor air damper (16) and a first heat exchanger (4b), in the form of a dehumidification coil. At least one supply air fan (1) draws a supply air stream (7), from a first arrangement (2), in the form of a suction chamber, through a filter (3) and a second heat exchanger (4a) , in the form of heating and cooling coil, and a third heat exchanger (4c) , in the form of a reheat coil, to be discharged through an air outlet (5) and into supply duct (6) . A second air stream (13), in the form of return air, is drawn substantially, or primarily, from the space through return duct (9) via an air inlet (8) and through return air chamber (2a) into suction chamber (2) . The outdoor air stream and return air streams are combined to form the supply air stream in the suction chamber (2) before passing through the second (4a) and third (4c) heat exchangers . The suction chamber (2) is configured such that the outdoor air (14) is conditioned by the dehumidification coil (4b) before passing through the second (4a) and third (4c) heat exchangers. The flow rates of the return air (13) and the outdoor air (14) are regulated by return air damper (15) and outdoor air damper (16) _/ respectively, which may be adjusted by electric actuators (not shown) . Gaskets (17a) join the supply air (6) and return air (9) ducts, which may be contained in common housing (6a) to the flat PAC underside (17b) directly surrounding air outlet (5) and air inlet (8) .

Components (1, 2, 3, 4, 15, 16, 4a, 4b and 4c) are largely housed in a largely thermally insulated casing (20) . The PAC includes a second arrangement, in the form of a second suction chamber (2b) , which is also housed in casing 20. At least one first compressor (21a), controlled by controller (22) in control panel (23), is connected via refrigeration pipes and associated refrigeration components (not shown) to the first heat exchanger (4b) , a fourth heat exchanger (27a) and the third heat exchanger (4c) .

The PAC includes a third arrangement, in the form of a third suction chamber (2c) , which is also housed in casing 20. At least one second compressor (21b), controlled by controller (22) in control panel (23), is connected via refrigeration pipes and associated refrigeration components (not shown) to the second heat exchanger (4a) and a fifth heat exchanger (27b) .

At least one fan (24) draws a third and a fourth air stream, in the form of outdoor air streams (26 and 26a) respectively, substantially from the outdoors (11), via optional outdoor air hail guard (41) and through the second (2b) and third (2c) suction chambers, and through the fourth heat exchanger (27a) and the fifth heat exchanger (27b) , respectively to be discharged to the outdoors via at least one air outlet (25) . The third (26) and fourth (26a) air streams are primarily outdoor air, which may also be referred to as fresh air from outside the space .

The fourth heat exchanger (27a) may be connected to the first heat exchanger (4b) only, or to the first (4b) and second (4a) heat exchangers, or to the first (4b) , second (4a) and third (4c) heat exchangers, or to the first (4b) and third (4c) heat exchangers by refrigeration piping to form part of a refrigeration cycle. The fifth heat exchanger (27b) may be connected to the second heat exchanger (4a) , or alternatively to the second (4a) and third (4c) heat exchangers.

When the third heat exchanger (4c) is connected by refrigeration piping to the first heat exchanger (4b) , the third heat exchanger (4c) rejects heat absorbed from outdoor air stream (14) . This effectively provides free reheating to the supply air stream (7) . Similarly, when the third heat exchanger (4c) is connected by refrigeration piping to the second heat exchanger (4a) , the third heat exchanger (4c) rejects heat absorbed from supply air stream (7) . This effectively provides free reheating to the supply air stream (7) .

Supply duct (6) and return duct (9), which may be contained in common housing (6a), penetrate roof sheeting (28), supported by purlins (29), via upstand (33a) with suitable under-flashing (not shown) to seal to roof sheeting (28) . Upstand (33a) may be structurally supported by roof beams (32) to solely carry a substantial portion of the weight of PAC (31a) , such as the weight of thermally insulated casing (20) and the components that it houses. Support flange (35) rests on upstand (33a) and may include overflashing (36) and a gasket (not shown) to upstand (33a) creating a watertight seal to upstand (33a) . The largely flat underside (17b) surrounding an air outlet (5) and an air inlet (8) of PAC (31a) rests on support flange (35) , which largely carries the weight of thermally insulated casing (20) and its components via gasket (17a), which in turn forms an airtight seal between PAC (31a) , supply duct (6) and return duct (9) . Supply duct (6) and return duct (9) are suspended from support flange (35) via common housing (6a) . PAC (31a) is additionally supported by support legs (33b) connected to roof beams (32) via seals (not shown) in roof sheeting (28) .

For reasons of simplicity, the illustrations referred to above neither show embodiments of the invention in which a proportion of return air is drawn from return air chamber (2a) to mix with outdoor air (14) drawn into heat exchanger (4b) , nor ones in which the first compressor (21a) and the second compressor (21b) are combined into a single compressor, and the fourth heat exchanger (27a) and the fifth heat exchanger (27b) are combined into a single heat exchanger.

In the claims which follow and in the preceding description, except where the context reguires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e., to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the apparatus.