INNER SHELL FOR AN AIR HANDLING UNIT

Abstract

 According to one aspect of the invention, object of the invention is inner shell for an air handling unit for operation in low temperature environmental conditions. The inner shell comprises two monolithic half-frames preferably made of plastic by molding. The half-frames comprise double-wall partitions with air pockets. The partitions are disposed between cold air pathways and warm air pathways eliminating cold bridging and avoiding water vapor condensation on walls of said pathways.

Description

TECHNICAL FIELD

[0001] The invention relates to air handling units, and in particular to an inner shell for an air handling unit for northern climate countries with a heat exchanger.

BACKGROUND ART

[0002] Modern people live indoors cut off from outdoor air for a considerable amount of time. A ventilation device for exchanging indoor air with outdoor air is essential. An air handling unit (AHU) is a component of building's cooling and heating system for forced air circulation for climate control in a habitable or industrial structure. An air handling unit typically comprise an outer shell, an inner shell, motors, additional heating/cooling means, blowers, heat exchangers of various configurations.

[0003] An air handling unit collects outside air and room air, removes dust and other particles from the collected air, adjusts the temperature and humidity and then supplies comfortable and refreshing air-conditioned air into the rooms through ducts. It produces, sends, and circulates chilled or heated air into the rooms via ducts at the same time discharging air from inside the room to outside of a building.

[0004] The outer shell acts as case and frame for an air handling unit and comprises multiple panels for isolating the inner components, including electrical equipment, heat exchanger, inner shell, of the air handling unit from environmental conditions outside the air handling unit. The inner shell is commonly used for support of heat exchanger as well as at least part of frame for two separate air ducts where the second part is formed by panels of the outer shell.

[0005] One type of heat exchangers used in air handling units is a rotary heat exchanger. A rotary heat exchanger is usually made of highly thermally conductive metal, such as aluminum, in a form of corrugated foil wound around the rotation axis. The alternating coils of film form a set of micro channels. By conductivity, the film heats up in contact with a warm air stream. The higher temperature air flows through the exchanger, heating it, then as the exchanger rotates, it contacts the colder air stream, which is then heated. In either heating or air conditioning applications, energy is recovered that would otherwise be wasted. Similarly, moisture recovery in a rotary exchanger is obtained by covering the exchanger with a hygroscopic substance - absorbing water from humid air and desorbing it in drier air, depending on building requirements for humidification or dehumidification.

[0006] Rotary heat exchangers do not freeze and perfectly performs even in the very low temperatures, down to -20°C. Rotary heat exchanger does not require condensate drainage although one can be provided.

[0007] At low air temperatures, such as -20 or less, thermal bridging inside an air handling unit and in particular at certain walls of inner shell facilitates formation of condensate on cold surfaces of cold air circulation ducts of an air handling unit due to thermal difference between cold side and warm side of the cold air circulation ducts' walls. When a large amount of condensate forms, it does not evaporate to the outside of the unit. Condensation needs to be avoided, especially in air handling units with rotary heat exchanger, because it can lead to corrosion and hygiene problems. Leaking condensate damages decoration or other equipment of a room where the air handling unit is located. In cold climate it can even lead to the formation of ice on the casing.

[0008] To reduce formation of condensate on walls of inner shell of air handling unit's air ducts, sides of walls, between airstreams having different air temperature, must be provided with means for reducing thermal bridging between two sides of air ducts' walls, thus reducing condensation of water vapor on the cold side of such wall.

[0009] Not limited to the above example with a rotary heat exchanger, the undesired thermal bridging in the inner shell is common to AHUs utilizing other types of heat exchangers as well. Technological solutions to reduce condensate is an area of improvement to all types of AHUs working in environments where fresh, outside air is significantly colder than exhaust, inside air.

[0010] International patent application Nr. PCT/KR2021/011501 discloses, as an example, a casing of an air conditioner made of a galvanized steel sheet, insulated on inside to suppress occurrence of dew condensation. Such solution presents high manufacturing cost of a frame as it is composed of multilayer multi-material sheets. Also, a multilayer composition is prone to manufacturing defects leading risk of corrosion of the steel layer, decrease in insulating properties over time of due to damage of an insulating layer. Given the physical nature of cold side of cold air duct partition to attract moisture, such insulation systems can be quickly compromised as a result of the moisture buildup intermixing with the insulation and freezing the same.

[0011] US patent No. US9,605,905 teaches that the problem of thermal bridging maybe solved by using sheets made of plastic providing limited heat transfer to cold side of a partition between different temperature air volumes. Also, PVC or other suitable plastic material will not deteriorate under varying environmental conditions like saltwater air, high humidity. Main disadvantage of using plastic sheet material is that it requires substantial thickness of a sheet for construction of inner frame of an air handling unit in order to substantially reduce thermal bridging without substantial increase in weight of the construction of the air handling unit.

[0012] The present invention is dedicated to overcoming of the above shortcomings and for producing further advantages over prior art.

BRIEF DESCRIPTION OF THE INVENTION

[0013] According to one aspect of the invention, object of the invention is an inner shell for an air handling unit for operation in low temperature environmental conditions. The inner shell comprises indoor air intake opening, indoor air pre-filter zone, indoor air filter insertion zone, indoor air post-filter zone, outdoor air intake opening, outdoor air pre-filter zone, outdoor air filter insertion zone, outdoor air post-filter zone, a partition between un-cooled indoors air zone and un-heated outdoors air zone comprising pre-filter zones, filter zones and post-filter zones, pre-heat-exchanger zone for un-cooled indoor air and pre-heat-exchanger zone for cold outdoor air, a heat exchanger mounting and operating zone, post-heat-exchanger zone for cooled indoor air and post-heat-exchanger zone for warmed outdoor air, a partition between un-cooled indoors air zone and cooled indoor air zone, a partition between un-heated outdoors air zone and heated outdoors air zone, a partition between un-cooled indoor air zone and cold outdoor air zone.

[0014] The inner shell further comprises a monolithic front half-frame and a monolithic back half-frame. The front half-frame comprises multiple double-wall segments with air pockets between said walls forming first half of a center partition between un-cooled indoors air zone and un-heated outdoors air zone comprising pre-filter zones, filter zones and post-filter zones; multiple double-wall with air pockets between said walls forming first half of first side partition, the side partition between un-cooled indoors air zone and cooled indoor air zone; multiple double-wall segments with air pockets between said walls forming first half of second side partition, the partition between un-heated outdoors air zone and heated outdoors air zone. The back half-frame comprises multiple double-wall segments with air pockets between said walls forming second half of the center partition between un-cooled indoors air zone and un-heated outdoors air zone comprising pre-filter zones, filter zones and post-filter zones; multiple double-wall segments with air pockets between said walls forming second half of the first side partition, the partition between un-cooled indoors air zone and cooled indoor air zone; multiple double-wall segments with air pockets between said walls forming second half of the second side partition, the partition between un-heated outdoors air zone and heated outdoors air zone.

[0015] All air pockets of the inner shell at their ends adjoining panels of the outer shell are closed tightly by surface of respective panels of the outer shell. Air pockets at opposite ends to those adjoining the panels of the outer shell are closed either by a partition formed in the wall of respective part of the inner shell frame or by forming a common air pocket - a half pocket of the front half-frame and half pocket of the back half-frame. The jointly formed air pockets are arranged at connection region between the front half-frame and the back half-frame.

[0016] The central partition of the inner shell is followed by the support pillars on both the front half-frame and back half-frame down to the bottom part of the inner shell. The support pillars preferably comprise double-wall structure with inner partitions connecting side walls and back wall support beams, distributed along the entire length of the support pillars. The side walls of the support pillars are preferably at right angle with the inner partitions and the inner partitions are preferably at right angle with back wall support beams.

[0017] The inner shell further comprises a first compartment for mounting air handling unit's electrical equipment and a second compartment for mounting air handling unit's further electrical equipment. The two compartments are disposed at opposite sides of the heat exchanger part of the inner shell.

[0018] According to another aspect of the invention, object of the invention is an air handling unit comprising inner shell according to first aspect of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Features of the invention believed to be novel and inventive are set forth with particularity in the appended claims. The invention itself, however, may be best understood by reference to the following detailed description of the invention, which describes exemplary embodiments, given in non-restrictive examples, of the invention, taken in conjunction with the accompanying drawings, in which:

Fig. 1 shows an example of assembled inner shell according to embodiment of the invention of an air handling unit with a rotary heat exchanger. Front half-frame of the inner shell according to embodiment of the invention is detailed.

Fig. 2 shows an example of assembled inner shell according to embodiment of the invention of an air handling unit with a rotary heat exchanger. Back half-frame of the inner shell is detailed.

Fig. 3 shows an example of double wall segments with air pockets of inner shell according to embodiment of the invention of an air handling unit with rotary heat exchanger.

Fig. 4 shows the inner shell according to the embodiment of the invention with example of mounted electrical equipment.

Fig. 5 shows the inner shell according to the embodiment of the invention with example of mounted electrical equipment and enclosed in outer shell of an air handling unit with rotary heat exchanger.

Fig. 6 shows an example of a rotary heat exchanger air handling unit comprising inner shell according to the invention and an outer shell.

Fig. 7 shows an example of a rotary heat exchanger air handling unit comprising inner shell according to the invention an outer shell and a detachable ventilation hood.

[0020] Preferred embodiments of the invention will be described herein below with reference to the drawings. Each figure contains the same numbering for the same or equivalent element.

DETAILED DESCRIPTION OF THE INVENTION

[0021] It should be understood that numerous specific details are presented in order to provide a complete and comprehensible description of the invention embodiment. However, the person skilled in art will understand that the embodiment examples do not limit the application of the invention which can be implemented without these specific instructions. Well-known methods, procedures and components have not been described in detail for the embodiment to avoid misleading. Furthermore, this description should not be considered to be constraining the invention to given embodiment examples but only as one of possible implementations of the invention.

[0022] According to one aspect of the invention an air handling unit (AHU) for operation in low temperature environmental conditions is disclosed. The air handling unit (AHU) comprises an outer shell (100) and an inner shell (200) and optionally a detachable ventilation hood (300).

[0023] Low temperature environmental conditions are such where water vapor condensates on a cold surface and freezes when opposite side of said cold surface is subjected to temperature above 0 °C. Low temperature is considered from -1 °C to -30 °C.

[0024] The outer shell (100) comprises a frame (101) comprising at least one front panel (102), at least one back panel (103), at least one first side panel (104) and at least one second side panel (105) and at least one top panel (106). The panels (101, 102, 103, 104, 105, 106) have single layer or multilayer construction characterized in sufficient structural rigidity, light weight, and thermal and sound insulation properties. The top panel (106) comprises outdoor air intake duct (108), for outdoor air having temperature, for example down to -20°. The top panel (106) also comprises indoor air intake duct (109), for indoor air having temperature, for example up to +22°. The top panel (106) also comprises heated outdoor air output duct (110), for supplying heated outdoor air having temperature, for example up to +22°. The top panel (106) also comprises cooled indoor air output duct (111), for expelling cooled indoor air having temperature, for example down to -14°. All panels of the outer shell (100) are assembled in an air-tight manner for securing the inner shell from thermal and humidity conditions from outside the outer shell.

[0025] According to another aspect of the invention an inner shell (200) of the air handling unit is disclosed. The inner shell (200) comprises a frame comprising a monolithic front half-frame (201) and a monolithic back half-frame (202). Both half-frames (201, 202) preferably have essentially identical structural elements. Both half frames (201, 202) are made from a monolithic material, such as molded plastic, for example PA6, PP, PE, ABS, PU for example by molding technique. Plastics, such as PA6 has lower thermal conductivity than metals and are highly durable, suitable for withstanding air handling unit's heat exchanger structural loads, non-corroding and is cheaper to manufacture than steel frames, using plastic molding methods.

[0026] A heat exchanger in the context of the invention is a heat exchanger operating with or without condensate drainage, preferably a rotary heat exchanger without condensate drainage, and in very low temperature, down to -20 °C and below, environmental conditions. Heat exchanger wheel (HEW) of the rotary heat exchanger in the preferred embodiment of the invention is preferably positionable width-wise with respect to inner shell (200) and outer shell (100) of the air handling unit. This allows accommodating larger heat exchanger wheel (HEW) compared to positioning the heat exchanger depth-wise. In this way depth of the inner shell (200) and outer shell (100) of the air handling unit is decreased increasing length of the construction.

[0027] It should be understood that the example with a rotary heat exchanger wheel (HEW) is not limiting regarding the use of a particular type of heat exchanger. Any type of heat exchanger suitable for operating with or without condensate drainage in very low temperature, down to -20 °C and below, environmental conditions, and in the inner shell according to any embodiment of the invention, can be used.

[0028] According to preferred embodiment of the invention, the front half-frame (201) comprises indoor air intake opening (203), a first half of indoor air pre-filter zone (204), a first half of indoor air filter insertion zone (205), a first half of indoor air post-filter zone (206) which is also a part of pre-heat-exchanger zone (PrHEZ) for un-cooled indoor air, a first half of a heat exchanger, for example a heat exchanger wheel (HEW), mounting and operating zone (207) for indoor air cooling. The front half-frame (201) further comprises a second half of outdoor air pre-filter zone (208), a second half of outdoor air filter insertion zone (209), a second half outdoor air post-filter zone (210), which is also a part of pre-heat-exchanger zone (PrHEZ') for un-heated outside air, a second half of the heat exchanger, for example a rotary heat exchanger wheel (HEW), mounting and operating zone (211) for outdoor air heating, a post-heat-exchanger zone (PoHEZ') for heated outside air.

[0029] The front half-frame (201) comprises multiple double-wall segments (C1", C2", C3") with air pockets between said walls forming first half of a center partition between un-cooled indoors air zone and un-heated outdoors air zone comprising pre-filter zones, filter zones and post-filter zones down to support pilar (250) respectfully. The front half-frame (201) further comprises multiple double-wall segments (204", 205", 206") with air pockets between said walls forming first half of first side partition, the side partition between un-cooled indoors air zone and cooled indoor air zone. The front half-frame (201) further comprises multiple double-wall segments (208", 209", 210") with air pockets between said walls forming first half of second side partition, the partition between un-heated outdoors air zone and heated outdoors air zone.

[0030] The multiple double-wall segments (, 204", 205", 206", 208"209", 210", C1", C2", C3") comprise multiple, preferably essentially vertical, inner partitions (P1) and multiple, preferably essentially horizontal, inner partitions (P2) forming multiple air pockets (P0) isolated one from another. The angle of said partitions (P1, P2) may vary if multiple individual air pockets (P0) are formed in said partitions. Thus, air convection is restricted inside these segments reducing thermal conductivity of the double-wall segments even further.

[0031] The front half-frame (201) further comprises first half (230) of first compartment for air handling unit equipment and first half (240) of second compartment for air handling unit other equipment. Structural rigidity, strength and stability of the inner shell (200) is enhanced by walls of integrally formed first half (230) of the first compartment for mounting air handling unit's (AHU) electrical equipment (EE"), such as a belt drive of the heat-exchanger wheel, or other equipment, and first half (240) of the second compartment for mounting air handling unit's (AHU) further electrical equipment (EE'), such as air heater equipment for additional air heating of the outside air, or further other equipment. The halves (230, 240) of the first and second compartments are disposed at opposite sides of the heat exchanger, for example a rotary heat exchanger, mounting part of the front half-frame (201). The walls of the compartments act as lower side supports, extending from bottom to about half of the front half-frame (201) of the inner shell (200).

[0032] The front half-frame (201) further comprises a support pilar (250) for support of the heat-exchanger, for example one end of heat exchanger's rotation axle, and for electrical cable management. Cables of equipment, such as sensors, can be extend in the pilar between bottom part of the front half-frame (201) and top part of a heat-exchanger's placement space without obstructing airflow or needing further cable management means. Said support pilar (250) is integral part of the front half-frame (201).

[0033] Structural rigidity of the inner shell (200) is provided with a continuous central support means comprising the central partition comprising double-wall segments (C1", C2", C3") of the front half-frame (201) continuously, as one body, followed by the support pilar (250) down to the bottom part of the front half-frame (201) of the inner shell (200). The support pilar (250) preferably comprises double-wall structure with inner partitions connecting side walls and back wall support beams, distributed along the entire length of the support pilar (250). The side walls of the support pillar (250) are preferably at right angle with the inner partitions and the inner partitions are preferably at right angle with the back wall support beams. Such structure ensures enhanced structural rigidity and strength of the inner shell (200).

[0034] The back-half frame (202) comprises outdoor air intake opening (212), a first half of outdoor air pre-filter zone (208'), a first half of outdoor air filter insertion zone (209'), a first half of outdoor air post-filter zone (210') which is also a part of pre-heat-exchanger zone (PrHEZ') for un-heated outside air, a first half of the heat exchanger, for example a rotary heat exchanger wheel (HEW), mounting and operating zone (211') for outdoor air heating. The back half-frame (202) further comprises a second half of indoor air pre-filter zone (204'), a second half of indoor air filter insertion zone (205'), a second half indoor air post-filter zone (206') which is also a part of pre-heat-exchanger zone (PrHEZ) for un-cooled indoor air, a second half of heat exchanger, for example a rotary heat exchanger wheel (HEW), mounting and operating zone (207') for indoor air cooling, and post-heat-exchanger zone (PoHEZ) for cooled inside air.

[0035] The back half-frame (202) comprises multiple double-wall segments (C1‴, C2‴, C3‴) with air pockets between said walls forming second half of the center partition between un-cooled indoors air zone and un-heated outdoors air zone comprising pre-filter zones, filter zones and post-filter zones down to support pilar (250') respectfully. The back half-frame (202) further comprises multiple double-wall segments (204‴, 205‴, 206‴) with air pockets between said walls forming second half of the first side partition, the partition between un-cooled indoors air zone and cooled indoor air zone. The back half-frame (202) further comprises multiple double-wall segments (208‴, 209‴, 210‴) with air pockets between said walls forming second half of the second side partition, the partition between un-heated outdoors air zone and heated outdoors air zone.

[0036] The multiple double-wall segments (204‴, 205‴, 206‴, 208‴, 209‴, 210‴, C1‴, C2‴, C3‴) comprise multiple essentially horizontal inner partitions (P1) and multiple essentially vertical inner partitions forming multiple air pockets (P0) isolated one from another. The angle of said partitions (P1, P2) may vary if multiple individual air pockets (P0) are formed in said partitions. Thus, air convection is restricted inside these segments reducing thermal conductivity of the double-wall segments even further.

[0037] The back half-frame (202) further comprises second half (230') of first compartment for air handling unit equipment and second half (240') of second compartment for air handling unit other equipment. Structural rigidity, strength and stability of the inner shell (200) is enhanced by walls of integrally formed second half (230') of the first compartment for mounting air handling unit's (AHU) electrical equipment (EE"), such as a belt drive of the heat-exchanger wheel, or other equipment, and second half (240') of the second compartment for mounting air handling unit's (AHU) further electrical equipment (EE'), such as air heater equipment for additional air heating of the outside air, or further other equipment. The halves (230', 240') of the first and second compartments are disposed at opposite sides of the heat exchanger, for example a rotary heat exchanger, mounting part of the front half-frame (201). The walls of the compartments act as lower side supports, extending from bottom to about half of the front half-frame (201) of the inner shell (200).

[0038] The back half-frame (202) comprises a support pilar (250') for support the heat exchanger, for example another end of heat-exchanger wheel's rotation axle, and for electrical cable management. Cables of equipment, such as sensors, can be extend in the pilar between bottom part of the back half-frame (202) and top part of heat-exchanger's placement space without obstructing airflow or needing further cable management means. Said support pilar (250') is integral part of the back half-frame (202).

[0039] Structural rigidity of the inner shell (200) is provided with a continuous central support means comprising the central partition comprising double-wall segments (C1‴, C2‴, C3‴) of the back half-frame (202) continuously, as one body, followed by the support pilar (250') down to the bottom part of the back half-frame (202) of the inner shell (200). The support pilar (250') preferably comprises double-wall structure with inner partitions connecting side walls and back wall support beams, distributed along the entire length of the support pilar (250'). The side walls of the support pillar (250') are preferably at right angle with the inner partitions and the inner partitions are preferably at right angle with the back wall support beams. Such structure ensures enhanced structural rigidity and strength of the inner shell (200).

[0040] The air handling unit (AHU) comprises two main air passages. The first passage is for indoor air cooling and subsequent exhaust of the indoor air from the air handling unit (AHU) comprises fluidly interconnected elements: indoor air intake duct (109), indoor air intake opening (203), a first half of indoor air pre-filter zone (204), a second half of indoor air pre-filter zone (204'), a first half of indoor air filter insertion zone (205), a second half of indoor air filter insertion zone (205'), a first half of indoor air post-filter zone (206), a second half outdoor air post-filter zone (206') both forming a pre-heat-exchanger zone (PrHEZ) for un-cooled indoor air, a first half of the heat exchanger, for example a rotary heat exchanger wheel (HEW), mounting and operating zone (207) for indoor air cooling, a second half of the heat exchanger, for example a rotary heat exchanger wheel (HEW), mounting and operating zone (207') for indoor air cooling, and post-heat-exchanger zone (PoHEZ) for cooled inside air. The supplied warm indoor air, for example +22 °C, is forced to flow through the heat exchanger, for example a heat exchanger wheel (HEW), from the pre-heat-exchanger zone (PrHEZ) to the post-heat-exchanger zone (PoHEZ). In the post-heat-exchanger zone (PoHEZ) the indoor air is cooled down to, for example -14 °C, and is forced to flow in a direction of air discharge fan (112) for discharge of cooled inside air to the outside of the air handling unit (AHU).

[0041] The second passage is for outdoor air warming and subsequent exhaust of the warmed outdoor air from the air handling unit (AHU) comprises fluidly interconnected elements: outdoor air intake duct (108), outdoor air intake opening (212), a first half of outdoor air pre-filter zone (208'), a second half of outdoor air pre-filter zone (208), a first half of outdoor air filter insertion zone (209'), a second half of outdoor air filter insertion zone (209), a first half of outdoor air post-filter zone (210') and a second half outdoor air post-filter zone (210) both forming a pre-heat-exchanger zone (PrHEZ') for un-heated outdoor air, a first half of the heat exchanger, for example a rotary heat exchanger wheel (HEW), mounting and operating zone (211') for outdoor air heating, a second half of heat exchanger, for example a rotary heat exchanger wheel (HEW), mounting and operating zone (211) for outdoor air heating, and post-heat-exchanger zone (PoHEZ') for heated outside air. The supplied cold outdoor air, for example -20 °C, is forced to flow through the heat exchanger, for example the heat exchanger wheel (HEW), from the pre-heat-exchanger zone (PrHEZ') to the post-heat-exchanger zone (PoHEZ'). In the post-heat-exchanger zone (PoHEZ') the indoor air is warmed up to, for example +22 °C, and is forced to flow in a direction of air discharge fan (113) for discharge of warmed outside air to the outside of the air handling unit (AHU).

[0042] The multiple double walled segments (204", 205", 206", 208", 209", 210", C1", C2", C3", 204‴, 205‴, 206'", 208", 209'", 210'", C1‴, C2‴, C3‴) are subjected to large differences of temperatures between one side and other side, i.e. one wall and another wall, of each segment. The double wall structure and the separated one from another air pockets highly enhances heat insulation properties preventing cold bridging and formation of condensate on the walls of the segments in the warm air flow part of each of the air passages. As a result, hereof a considerable temperature difference may exist between double wall segments facing the cold air and the warm air.

[0043] All air pockets (P0) at their ends adjoining the front and back panels (102, 103) of the outer shell (100) are closed tightly by the surface of respective panels of the outer shell (100). At opposite ends to those adjoining the front and back panels (102, 103) of the outer shell (100), air pockets (P0) are closed either by partitions (P1) formed in the wall of respective part of the inner shell (200) frame or by forming a common air pocket by a half pocket of the front half-frame (201) and half pocket of the back half-frame (202). The jointly formed air pockets are arranged at the connection region between the front half-frame (201) and the back half-frame (202). The front half-frame (201) and the back half-frame (202) are joined in an air-tight manner around entire joint seam (220) of the two half-frames (201, 202).

[0044] The air-tight connection of the two half-frames (201, 202) is provided by combination of: insertion fittings (F1) of part of front half-frame (201) around its perimeter for joining with the back half-frame (202) into part of the back half-frame (202) around its perimeter; precise alignment means (F2), for example slidingly engaging for precise alignment of front half-frame (201) and back half-frame (202), where the front half-frame is provided with first alignment element of the precise alignment means (F2), and the back half-frame (202) is provided with second alignment element of the precise alignment means (F2); and securing means (F3) for locking each of the two half-frames (201, 202) between each other by locking means, for example bolt and nut. The connection means (F1, F2, F3) are provided around entire perimeter of connecting seam (220), where the top and the bottom of the front half-frame (201) and the back half-frame (202) of the inner shell (200) of the air handling unit (AHU) are joined mainly by insertion fittings (F1).

[0045] The airtight connecting seam (220) is provided with a rubber spacer (not shown) around entire joint perimeter in an air gap (P01) further improving airtight connection of both half-frames (201,202).

[0046] Preferably both half-frames (201, 202) are provided with protrusions (F) extending width wise on external walls of the half-frames (201, 202) along the air pockets (P0) and are preferably formed as extensions of the essentially horizontal inner partitions (P2) improving stability and rigidity of both half-frames. The protrusions prevent the inner shell from deforming.

[0047] The air handling unit (AHU) optionally comprises a detachable ventilation hood (300). The detachable ventilation hood (300) is secured to bottom of the outer shell (100) of the air handling unit (AHU). Air duct from the detachable ventilation hood (300) is fluidly connected with the pre-heat-exchanger zone (PrHEZ) for indoor air cooling.

[0048] The air handling unit (AHU) comprises electrical equipment required for running an air handling unit. The said electrical equipment is not specified as it is standard electrical equipment required for running an air handling unit with or without a further outdoor heating means.

[0049] In another examples of embodiment of the invention the air handling unit (AHU) comprises all the above except each example comprises different type of heat exchanger heat exchanger which does not require condensate drainage, suitable for operating in low temperature climate conditions, such as -20 °C or lower.

[0050] Although numerous characteristics and advantages together with structural details and features have been listed in the present description of the invention, the description is provided as an example fulfilment of the invention. Without departing from the principles of the invention, there may be changes in the details, especially in the form, size and layout, in accordance with most widely understood meanings of the concepts and definitions used in claims.

Claims

1. An inner shell for an air handling unit for operation in low temperature environmental conditions, the inner shell comprising indoor air intake opening, indoor air pre-filter zone, indoor air filter insertion zone, indoor air post-filter zone, outdoor air intake opening, outdoor air pre-filter zone, outdoor air filter insertion zone, outdoor air post-filter zone, a partition between un-cooled indoor air zone and un-heated outdoor air zone, pre-heat-exchanger zone for cold outdoor air and pre-heat-exchanger zone for warm indoor air, a heat exchanger mounting and operating zone, post-heat-exchanger zone for cooled indoor air and post-heat-exchanger zone for warmed outdoor air, a partition between un-cooled indoor air zone and cooled indoor air zone, a partition between un-heated outdoor air zone and heated outdoor air zone, a partition between un-cooled indoor air zone and cold outdoor air zone characterized in that
the inner shell (200) comprises a monolithic front half-frame (201) and a monolithic back half-frame (202),

where the front half-frame (201) comprises indoor air intake opening (203), a first half of indoor air pre-filter zone (204), a first half of indoor air filter insertion zone (205), a first half of indoor air post-filter zone (206) which is also a part of pre-heat-exchanger zone (PrHEZ) for un-cooled indoor air, a first half of a heat exchanger mounting and operating zone (207) for indoor air cooling, a second half of outdoor air pre-filter zone (208), a second half of outdoor air filter insertion zone (209), a second half outdoor air post-filter zone (210), which is also a part of pre-heat-exchanger zone (PrHEZ') for un-heated outside air, a second half of the heat exchanger mounting and operating zone (211) for outdoor air heating, a post-heat-exchanger zone (PoHEZ') for heated outside air, where the front half-frame (201) comprises multiple double-wall segments (C1", C2", C3") with air pockets (P0) between said walls forming first half of a center partition between un-cooled indoors air zone and un-heated outdoors air zone; multiple double-wall segments (204", 205", 206") with air pockets (P0) between said walls forming first half of first side partition, the side partition between un-cooled indoors air zone and cooled indoor air zone; multiple double-wall segments (208", 209", 210") with air pockets (P0) between said walls forming first half of second side partition, the partition between un-heated outdoors air zone and heated outdoors air zone,

where the back half-frame (202) comprises outdoor air intake opening (212), a first half of outdoor air pre-filter zone (208'), a first half of outdoor air filter insertion zone (209'), a first half of outdoor air post-filter zone (210') which is also a part of pre-heat-exchanger zone (PrHEZ') for un-heated outside air, a first half of the heat exchanger mounting and operating zone (211') for outdoor air heating, a second half of indoor air pre-filter zone (204'), a second half of indoor air filter insertion zone (205'), a second half indoor air post-filter zone (206') which is also a part of pre-heat-exchanger zone (PrHEZ) for un-cooled indoor air, a second half of heat exchanger mounting and operating zone (207') for indoor air cooling, and post-heat-exchanger zone (PoHEZ) for cooled inside air, where the back half-frame (202) comprises multiple double-wall segments (C1‴, C2‴, C3‴) with air pockets (P0) between said walls forming second half of the center partition between un-cooled indoors air zone and un-heated outdoors air zone; multiple double-wall segments (204‴, 205‴, 206‴) with air pockets (P0) between said walls forming second half of the first side partition, the partition between un-cooled indoors air zone and cooled indoor air zone; multiple double-wall segments (208‴, 209‴, 210‴) with air pockets (P0) between said walls forming second half of the second side partition, the partition between un-heated outdoors air zone and heated outdoors air zone.

2. Inner shell according to claim 1, where the multiple double-wall segments (204", 205", 206", 208", 209", 210", C1", C2", C3", 204‴, 205‴, 206‴, 208‴, 209‴, 210‴, C1‴, C2‴, C3‴) comprise multiple inner partitions (P1, P2) forming multiple air pockets (P0) isolated one from another.

3. Inner shell according to claim 1 or 2, where the front half-frame (201) further comprises first half (230) of first compartment for mounting air handling unit's (AHU) electrical equipment and first half (240) of second compartment for mounting air handling unit's (AHU) electrical equipment, where the halves (230, 240) of the compartments are integral parts of the front half-frame (201), where the back half-frame (202) further comprises second half (230') of first compartment for mounting air handling unit's (AHU) electrical equipment and second half (240') of second compartment for mounting air handling unit's (AHU) electrical equipment, where the halves (230', 240') of the compartments are integral parts of the back half-frame (202).

4. Inner shell according to any one of claims 1 - 3, where the front half-frame (201) further comprises a support pilar (250) and the back half-frame (202) further comprises a support pilar (250') for support of the heat-exchanger and for electrical cable management.

5. Inner shell according to claim 4, where the support pillars (250, 250') comprises double-wall structure with inner partitions connecting side walls and support beams of back wall of the support pillars (250, 250'), distributed along the entire length of the support pillars (250, 250').

6. Inner shell according to any one previous claim where heat exchanger support and operation zone is rotary heat exchanger wheel (HEW) support and operation zone.

7. Inner shell according to any one previous claims, where inner shell (200) comprises insertion fittings (F1) of part of front half-frame (201) around its perimeter for joining with the back half-frame (202) into part of the back half-frame (202) around its; precise alignment means (F2), for example slidingly engaging for precise alignment of front half-frame (201) and back half-frame (202), where front half-frame is provided with first alignment element of the precise alignment means (F2), and the back half-frame (202) is provided with second alignment element of the precise alignment means (F2); and securing means (F3) for locking each of the two half-frames (201, 202) between each other by locking means, where the connection means (F1, F2, F3) are provided around entire perimeter of connecting seam (220), where the top and the bottom of the front half-frame (201) and the back half-frame (202) of the inner shell (200) of the air handling unit (AHU) are joined mainly by insertion fittings (F1).

8. An air handling unit comprising an outer shell and an inner shell, where the inner shell (200) is according to any of the previous claims.

Drawing